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Plc Based Car Parking Guidance System
53
PLC BASED CAR PARKING GUIDANCE SYSTEM ACKNOWLEDGEMENT
description
Electronics
Transcript of Plc Based Car Parking Guidance System
PLC BASED CAR PARKING
GUIDANCE SYSTEM
ACKNOWLEDGEMENT
We take the opportunity to thank one and all who have helped us in making this project successful We are extremely happy to present this project under the esteemed guidance of Prof P Sri Hari Head of department Department of Electronics and Communication Engineering
We are grateful to Prof PSri Hari HOD Electronics and Communication Engineering VNRVJIET for his encouragement for carrying out this project
We would also like to thank all the staff members of ECE department for their help and kind support in times of need
Finally our humble thanks to the almighty but for whom we did none
ACKNOWLEDGEMENT
We owe our profound acknowledgement to all those people who made this
project successful We present the names of those people to whom we are very much
grateful We would like to express our most sincere thanks to all those people who are
involved in our project work Any omissions are regretted We express our deep sense
of gratitude to Automation Solutions KPHB Hyderabad for permitting us to work in their
organization
We express our special gratitude and thanks to MrManohar CEO Automation
Solutions Hyderabad for his kind co-operation without whom the project training would
not have been completed
We would like to express our humble and sincere thanks to MsNeelima
Automation Solutions Hyderabad for her encouragement and constant support
throughout the training
We take the opportunity to thank our Head of Department Prof PSri Hari for his
timely advice and guidance while pursuing this project as well as throughout the BTech
course Our sincere thanks to our beloved professor and internal guide for his guidance
and contribution in developing the project
ABSTRACT
In this fast developing science revolutionary era automation of an industry has become a necessity A PLC (Programmable Logic Controller) is a programmable system used for automation The Programmable Logic Controller may be defined as ldquoA PLC is a microprocessor based specialized computer that carries out the control functions of many types and levels of complexityrdquo
A PLC has many input terminals through which it interprets high and low logical states from sensors and switches It also has many output terminals through which it outputs high and low signals to power lights solenoids contactors small motors and other devices lending themselves to onoff control
We have designed a kit for automating a car parking guidance system For this a PLC (Siemens S7-200) has been used The PLC has been pre-programmed and is the brain of the system It reads the inputs from the various sensors and makes logical decisions These logical decisions are given to the PLC by using a suitable programming language Accordingly the necessary operation is carried out Our project illustrates only a simple application of the PLC while the PLC is a powerful tool the applications of which are innumerable and complex
PLATFORM S7-200 PLC
PROGRAMMING LANGUAGE LADDER DIAGRAMS
SOFTWARE S7 MICROWIN
KEYWORDS SENSORS BUZZERS LEDS AUTOMATION
LADDER LOGIC MEMORY
1 INTRODUCTION
A programmable logic controller (PLC) or programmable controller is a digital computer used for automation of electromechanical processes such as control of machinery on factory assembly lines amusement rides or lighting fixtures PLCs are
used in many industries and machines such as packaging and semiconductor machines Unlike general-purpose computers the PLC is designed for multiple inputs and output arrangements extended temperature ranges immunity to electrical noise and resistance to vibration and impact Programs to control machine operation are typically stored in battery-backed or non-volatile memory A PLC is an example of a real time system since output results must be produced in response to input conditions within a bounded time otherwise unintended operation will result
A PLC has many input terminals through which it interprets high and low logical states from sensors and switches It also has many output terminals through which it outputs high and low signals to power lights solenoids contactors small motors and other devices lending themselves to onoff control In an effort to make PLCs easy to program their programming language was designed to resemble ladder logic diagrams Thus an industrial electrician or electrical engineer accustomed to reading ladder logic schematics would feel comfortable programming a PLC to perform the same control functions
PLCs are industrial computers and as such their input and output signals are typically 120 volts AC just like the electromechanical control relays they were designed to replace Although some PLCs have the ability to input and output low-level DC voltage signals of the magnitude used in logic gate circuits this is the exception and not the rule
The actual logic of the control system is established inside the PLC by means of a computer program This program dictates which output gets energized under which input conditions Although the program itself appears to be a ladder logic diagram with switch and relay symbols there are no actual switch contacts or relay coils operating inside the PLC to create the logical relationships between input and output These are imaginary contacts and coils if you will The program is entered and viewed via a personal computer connected to the PLCs programming port
The true power and versatility of a PLC is revealed when we want to alter the behavior of a control system Since the PLC is a programmable device we can alter its behavior by changing the commands we give it without having to reconfigure the electrical components connected to it
One of the advantages of implementing logical control in software rather than in hardware is that input signals can be re-used as many times in the program as is necessary Another advantage of PLCs that simply cannot be duplicated by electromechanical relays is remote monitoring and control via digital computer networks Because a PLC is nothing more than a special-purpose digital computer it has the ability to communicate with other computers rather easily
2 HISTORY
21 ORIGIN
The PLC was invented in response to the needs of the American automotive manufacturing industry Programmable controllers were initially adopted by the automotive industry where software revision replaced the re-wiring of hard-wired control panels when production models changed
Before the PLC control sequencing and safety interlock logic for manufacturing automobiles was accomplished using hundreds or thousands of relays cam timers and drum sequencers and dedicated closed-loop controllers The process for updating such facilities for the yearly model change-over was very time consuming and expensive as the relay systems needed to be rewired by skilled electricians
In 1968 GM Hydramatic (the automatic transmission division of General Motors) issued a request for proposal for an electronic replacement for hard-wired relay systems
The winning proposal came from Bedford Associates of Bedford Massachusetts The first PLC designated the 084 because it was Bedford Associates eighty-fourth project was the result Bedford Associates started a new company dedicated to developing manufacturing selling and servicing this new product MODICON which stood for MOdular DIgital CONtroller One of the people who worked on that project was Dick Morley who is considered to be the father of the PLC The MODICON brand was sold in 1977 to Gould Electronics and later acquired by German Company AEG and then by French Schneider Electric the current owner
One of the very first 084 models built is now on display at Modicons headquarters in North Andover Massachusetts It was presented to Modicon by GM when the unit was retired after nearly twenty years of uninterrupted service Modicon used the 84 moniker at the end of its product range until the 984 made its appearance
The automotive industry is still one of the largest users of PLCs
22 DEVELOPMENT
Early PLCs were designed to replace relay logic systems These PLCs were programmed in ladder logic which strongly resembles a schematic diagram of relay logic Modern PLCs can be programmed in a variety of ways from ladder logic to more traditional programming languages such as BASIC and C Another method is State Logic a very high-level programming language designed to program PLCs based on state transition diagrams
Many of the earliest PLCs expressed all decision making logic in simple ladder logic which appeared similar to electrical schematic diagrams This program notation was chosen to reduce training demands for the existing technicians Other early PLCs used a form of instruction list programming based on a stack-based logic solver
23 PROGRAMMING
Early PLCs up to the mid-1980s were programmed using proprietary programming panels or special-purpose programming terminals which often had dedicated function keys representing the various logical elements of PLC programs Programs were stored on cassette tape cartridges Facilities for printing and documentation were very minimal due to lack of memory capacity The very oldest PLCs used non-volatile magnetic core memory
24 FUNCTIONALITY
The functionality of the PLC has evolved over the years to include sequential relay control motion control process control distributed control systems and networking The data handling storage processing power and communication capabilities of some modern PLCs are approximately equivalent to desktop computers PLC-like programming combined with remote IO hardware allow a general-purpose desktop computer to overlap some PLCs in certain applications
PLC ARCHITECTURE
CPU
Power Supply
Memory
Input Blocks
Output Blocks
Communications
Expansion Connections
BLOCK DIAGRAM OF PLC
SENSORS
PLC COMPARED WITH OTHER CONTROL SYSTEMS
PLCs are well-adapted to a range of automation tasks These are typically industrial processes in manufacturing where the cost of developing and maintaining the automation system is high relative to the total cost of the automation and where changes to the system would be expected during its operational life PLCs contain input and output devices compatible with industrial pilot devices and controls little electrical design is required and the design problem centers on expressing the desired sequence of operations in ladder logic (or function chart) notation PLC applications are typically highly customized systems so the cost of a packaged PLC is low compared to the cost of a specific custom-built controller design On the other hand in the case of mass-produced goods customized control systems are economic due to the lower cost of the components which can be optimally chosen instead of a generic solution and where the non-recurring engineering charges are spread over thousands or millions of units
For high volume or very simple fixed automation tasks different techniques are used A microcontroller-based design would be appropriate where hundreds or thousands of units will be produced and so the development cost (design of power supplies and inputoutput hardware) can be spread over many sales and where the end-user would not need to alter the control Automotive applications are an example millions of units are built each year and very few end-users alter the programming of these controllers
Power supply
Input
Module
Memory
Processor
Output
Module
However some specialty vehicles such as transit busses economically use PLCs instead of custom-designed controls because the volumes are low and the development cost would be uneconomic
Very complex process control such as used in the chemical industry may require algorithms and performance beyond the capability of even high-performance PLCs Very high-speed or precision controls may also require customized solutions for example aircraft flight controls
Programmable controllers are widely used in motion control positioning control and torque control Some manufacturers produce motion control units to be integrated with PLC so that G-code (involving a CNC machine) can be used to instruct machine movements
PLCs may include logic for single-variable feedback analog control loop a proportional integral derivative or PID controller A PID loop could be used to control the temperature of a manufacturing process for example Historically PLCs were usually configured with only a few analog control loops where processes required hundreds or thousands of loops a distributed control system (DCS) would instead be used As PLCs have become more powerful the boundary between DCS and PLC applications has become less distinct
PLCs have similar functionality as Remote Terminal Units An RTU however usually does not support control algorithms or control loops As hardware rapidly becomes more powerful and cheaper RTUs PLCs and DCSs are increasingly beginning to overlap in responsibilities The industry has standardized on the IEC 61131-3 functional block language for creating programs to run on RTUs and PLCs although nearly all vendors also offer proprietary alternatives and associated development environments
DISADVANTAGES OF lsquoHARD WIRED LOGIC CONTROLrsquo
Bulky panels
Complex wiring
Longer project time
Difficult maintenance and troubleshooting
ADVANTAGES OF lsquoPLCSrsquo
Reduced space
Ease of maintenance
Economical
Greater life amp reliability
Tremendous flexibility
Shorter project time
Easier storage archiving and documentation
WHAT CONSTITUTES A PLC
The PLC is programmed interface between the Input field elements amp output field
elements
PLC consist of
Hardware
Input Module
CPU (Central Process Unit)
Program memory
Output module
Power Supply
Software
Application Software (Logic)
Basic Software
Communication Accessories
Communication Adapter
INPUT-OUTPUT
Input and output (IO) modules connect the PLC to
sensors and actuators
Provide isolation for the low-voltage low-current
signals
Wide range of IO modules available including
Digital (logical) IO modules and Analogue (continuous) IO modules
Analogue input cards convert continuous signals via an AD converter into discrete
values for the PLC
Analogue output cards convert digital values in then PLC to continuous signals via a
DA converter
Resolution can be important in choosing an applicable card
Module receptacle for battery EEPROM
CPU statu
s LEDrsquo
sCommunicatio
ns interfa
ce
Status LEDrsquos of
the inputs
and outputs
Fixing holes for wall
mounting
Locking clip for DIN rail mounting
Analog potentiometer
Removable
connection
terminals(on 224 226)
Example for a temperature input of 0 to 100 degrees C
For 8 bit resolution the value in the PLC is 0 to 255
For 12 bit resolution the value in the PLC is 0 to 4095
For 16 bit resolution the value in the PLC is 0 to 32768
SPECIAL MODULES
RF ID
Modem modules
Load Cell
Stepper Modules
Temperature Sensor
High Speed Counters
Position Control Cards
Field Bus Cards
o Device Net Profibus Ethernet etc
ELEMENTS OF INPUTS
Digital Inputs
push button
limit switches
Sensors
o Proximity Sensors
o Photo Sensors
Micro Switches
Toggle Switches
Analog Inputs
Pressure Transmitters
Flow Transmitter
Level Transmitter
Thermo Couples
Load Cell
ELEMENTS OF OUTPUTS
Digital Outputs
Relays
Contactors
Indication Lamps
Valves
Analog Outputs
Flow Control Valves
Pressure Control Valves
Drive Inputs
BASIC ELEMENTS OF A PROGRAM
A program block is composed of executable code and comments The executable codes consist of a main program and any subroutines or interrupt routines The code is compiled and downloaded to the S7-200 the program comments are not You can use the organizational elements (main program subroutines and interrupt routines) to structure your control program
Main ProgramThe main body of the program contains the instructions that control your application The S7-200 executes these instructions sequentially once per scan cycle The main program is also referred to as OB1
SubroutinesThese optional elements of your program are executed only when called by the main program by an interrupt routine or by another subroutine Subroutines are useful in cases where you want to execute a function repeatedly Rather than rewriting the logic for each place in the main program where you want the function to occur you can write the logic once in a subroutine and call the subroutine as many times as needed during the main program Subroutines provide several benefits
1048600 Using subroutines reduces the overall size of your program 1048600 Using subroutines decreases your scan time because you have moved the code out of the main program The S7-200 evaluates the code in the main program every scan cycle whether the code is executed or not but the S7-200 evaluates the code in the subroutine only when you call the subroutine and does not evaluate the code during the scans in which the subroutine is not called 1048600 Using subroutines creates code that is portable You can isolate the code for a function in a subroutine and then copy that subroutine into other programs with Interrupt RoutinesThese optional elements of your program react to specific interrupt events You design an interrupt routine to handle a pre-defined interrupt event Whenever the specified event occurs the S7-200 executes the interrupt routineThe interrupt routines are not called by your main program You associate an interrupt routine with an interrupt event and the S7-200 executes the instructions in the interrupt routine only on each occurrence of the interrupt event Other Elements of the ProgramOther blocks contain information for the S7-200 You can choose to download these blocks when you download your programSystem BlockThe system block allows you to configure different hardware options for the S7-200Data BlockThe data block stores the values for different variables (V memory) used by your program You can use the data block to enter initial values for the data
PROGRAMMING LANGUAGES IN PLC
IL (Instruction List) ndash mnemonic programming
LD (Ladder Diagram) ndash Relay logic
ST (Structured Text) ndash A C like programming language
FDB (Functional Block Diagram) ndash Graphical dataflow programming language
SFC (Sequential Flow Chart) ndash Graphical method for structured programs
Basic PLC Memory
Memory on a PLC is separated into 3 main areas
LOAD Memory
Can be RAM (dynamic) or EEPROM (retentive)
Used to store user programs
WORK Memory
Memory is RAM
When PLC starts Program is copied from LOAD memory to
WORK memory The program is then executed from Work
memory
SYSTEM Memory
Memory is RAM
Is used by micro-controller to implement counters timers interrupt
stacks etc
Contains a bit for each D I0
Contains ldquoMarker Memoryrdquo Marker memory is a free area of RAM
that can be used by the programmer
Contains ldquoProcess Input and Output Imagesrdquo Periodically the PLC
will store the states of the inputs to the Process Input Image and
Process Output Image to the output
SELECTION OF A PLC
Selection of PLC Based on
No of Inputs amp Outputs
Input Voltage
Memory
Scan Time
Special IO modules
Expansion Capabilities
Stand alone or Networked
Communication Capabilities
HOW PLC WORKS
Step 1-CHECKING INPUT STATUS
o PLC Scans each input
o Records the data in work memory
Step 2-EXECUTE PROGRAM
o PLC goes through the program logic step by step
o PLC executes the program depending on input status
o Write the output image in work memory
Step 3-UPDATE OUTPUT STATUS
o Changes the statues of the output onoff
o Again starts the cycle from step one
FEATURES OF S7-200
Allows Your Program to Immediately Read or Write the IO
Allows Your Program to Interrupt the Scan Cycle
Allows You to Allocate Processing Time for Communications
Tasks
Allows You to Set the States of Digital Outputs for Stop
CHECK
INPUT STATUS
EXECUTE
PROGRAM
UPDATE
OUTPUT STATUS
Mode
Allows You to Define Memory to Be Retained on Loss of Power
Allows You to Filter the Digital Inputs
Allows You to Filter the Analog Inputs
Allows You to Catch Pulses of Short Duration
Provides Password Protection
Provides Analog Adjustment Potentiometers
Provides High-speed IO
TECHNICAL FEATURES OF S7-200
Several models of CPUrsquos
o CPU 221 6in4out 2Kw program
o CPU 222 8in6out 2Kw program
o CPU 224 14in10out 4Kw program
o CPU 226 24in16out 4Kw program
Up to 256 digital input-outputs
Up to 32 analog channels
256 timers 256 counters
Built-in EEPROM memory
Real-time clockcalendar
Built-in communications
Password protection
Memory module
Removable input-output connectors
Wide range of expansion modules
o 8 pt input and output
o 4488 amp1616 inout combination
o 4 channel analog in 2 channel analog out
o 4 ch1ch analog inout combination
o 2 channel RTD in
o 4 channel thermocouple in
o PROFIBUS-DP Slave
o AS Interface master
SELECTING THE OPERATING MODE FOR THE S7- 200 CPU
The S7-200 has two modes of operation STOP mode and RUN mode The status LED on the front of the CPU indicates the current mode of operation In STOP mode the S7-200 is not executing the program and you can download a program or the CPU configuration In RUN mode the S7-200 is running the program
1048600 The S7-200 provides a mode switch for changing the mode of operation You can use the mode switch (located under the front access door of the S7-200) to manually select the operating mode setting the mode switch to STOP mode stops the execution of the program setting the mode switch to RUN mode starts the execution of the program and setting the mode switch to TERM (terminal) mode does not change the operating mode
If a power cycle occurs when the mode switch is set to either STOP or TERM the
S7-200 goes automatically to STOP mode when power is restored If a power cycle occurs when the mode switch is set to RUN the S7-200 goes to RUN mode when power is restored
1048600 STEP 7--MicroWIN allows you to change the operating mode of the online S7-200 To enable the software to change the operating mode you must manually set the mode switch on the S7-200 to either TERM or RUN You can use the PLC gt STOP or PLC gt RUN menu commands or the associated buttons on the toolbar to change the operating mode
1048600 You can insert the STOP instruction in your program to change the S7-200 to STOP mode This allows you to halt the execution of your program based on the program logic
ERRORS IN S7-200
Non-Fatal Errors
Non-fatal errors are those indicating problems with the construction of the user program with the execution of an instruction in the user program and with expansion IO modules You can use STEP 7--MicroWIN to view the error codes that were generated by the non-fatal error There are three basic categories of non-fatal errors
Program-compile errorsThe S7-200 compiles the program as it downloads If the S7-200 detects that the program violates a compilation rule the download is aborted and an error code is generated (A program that was already downloaded to the S7-200 would still exist in the EEPROM and would not be lost) After you correct your program you can download it again
IO errorsAt startup the S7-200 reads the IO configuration from each module During normal operation the S7-200 periodically checks the status of each module and compares it against the configuration obtained during startup If the S7-200 detects a difference the S7-200 sets the configuration error bit in the module error register The S7-200 does not read input data from or write output data to that module until the module configuration again matches the one obtained at startupThe module status information is stored in special memory (SM) bits Your program can monitor and evaluate these bits Refer to Appendix D for more information about the SM bits used for reporting IO errors SM50 is the global IO error bit and remains set while an error condition exists on an expansion module
Program execution errorsYour program can create error conditions while being executed These errors can result from improper use of an instruction or from the processing of invalid data by an instruction For example an indirect-address pointer that was valid when the program compiled could be modified during the execution of the program to point to an out-of-range address This is an example of a run-time programming problem SM43 is setupon the occurrence of a run-time programming problem and remains set while the S7-200 is in RUN mode Program execution error information is stored in special memory (SM) bits Your program can monitor and evaluate these bits The S7-200 does not change to STOP mode when it detects a non-fatal error It only logs the event in SM memory and continues with the execution of your program However you can design your program to force the S7-200 to STOP mode when a non-fatal error is detected
Fatal Errors
Fatal errors cause the S7-200 to stop the execution of your program Depending upon the severity of the fatal error it can render the S7-200 incapable of performing any or all functions The objective for handling fatal errors is to bring the S7-200 to a safe state from which the S7-200 can respond to interrogations about the existing error conditions When a fatal error is detected the S7-200 changes to STOP mode turns on the System Fault LED and the STOP LED overrides the output table and turns off the outputsThe S7-200 remains in this condition until the fatal error condition is corrected
Once you have made the changes to correct the fatal error condition use one of the following methods to restart the S7-200 1048600 Turn the power off and then on 1048600 Change the mode switch from RUN or TERM to STOP 1048600 Select the PLC gt Power-Up Reset menu command from STEP 7--MicroWIN
to restart the S7-200This forces the S7-200 to restart and clear any fatal errors
Restarting the S7-200 clears the fatal error condition and performs power-up diagnostic testing to verify that the fatal error has been corrected If another fatal error condition is found the S7-200 again sets the fault LED indicating that an error still exists Otherwise the S7-200 begins normal operation
Some error conditions can render the S7-200 incapable of communication In these cases you cannot view the error code from the S7-200 These types of errors indicate hardware failures that require the S7-200 to be repaired they cannot be fixed by changes to the program or clearing the memory of the S7-200
APPLICATIONS OF S7-200
Conveyer Systems
Elevators
Test Stations
Placement Systems
Woodworking Machinery
Packaging Equipment
Car Wash Automation
Remote Monitoring And Controlling For Water Wastewater
FEATURES OF LADDER DIAGRAMS
The LAD editor displays the program as a graphical representation similar to electrical wiring diagrams
Ladder programs allow the program to emulate the flow of electric current from a power source through a series of logical input conditions that in turn enable logical output conditions
A LAD program includes a left power rail that is energized Contacts that are closed allow energy to flow through them to the next element and contacts that are open block that energy flow
The logic is separated into networks The program is executed one network at a time from left to right and then top to bottom as dictated by the program Figure shows an example of a LAD program
The various instructions are represented by graphic symbols and include three basic forms
Contacts represent logic input conditions such as switches buttons or internal conditions
Coils usually represent logic output results such as lamps motor starters interposing relays or internal output conditions
Boxes represent additional instructions such as timers counters or math instructions Figure Sample LAD Program
Consider these main points when you select the LAD editor 1048600 Ladder logic is easy for beginning programmers to use 1048600 Graphical representation is easy to understand and is popular around the world 1048600 The LAD editor can be used with both the SIMATIC and IEC 1131--3 Instruction sets
1048600 You can always use the STL editor to display a program created with
the SIMATIC LAD editor
COMPONENTS LIST
Cardboard of 4050 sqcm
PLC S7-200
Sensors
LEDS
Buzzers
Motor
Contactors
Power supply
12v DC battery
Connecting wires
PPI Cable
SENSORS
A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact A proximity sensor often emits an electromagnetic or electrostatic field or a beam of electromagnetic radiation (infrared for instance) and looks for changes in the field or return signal The object being sensed is often referred to as the proximity sensors target Different
proximity sensor targets demand different sensors For example a capacitive or photoelectric sensor might be suitable for a plastic target an inductive proximity sensor requires a metal target
The maximum distance that this sensor can detect is defined nominal range Some sensors have adjustments of the nominal range or means to report a graduated detection distance
Proximity sensors can have a high reliability and long functional life because of the absence of mechanical parts and lack of physical contact between sensor and the sensed object
IEC 60947-5-2 defines the technical details of proximity sensors
A proximity sensor adjusted to a very short range is often used as a touch switch
Applications
Car bumpers that sense distance to nearby cars for parking
Ground proximity warning system for aviation safety Vibration Position measurements of rotating shafts in
machinery Sheet break sensing in paper machine Anti-aircraft artillery
LEDS
Example Circuit symbol
FunctionLEDs emit light when an electric current passes through them
Testing an LED
Never connect an LED directly to a battery or power supply
LEDs must have a resistor in series to limit the current to a safe value for quick testing purposes a 1k resistor is suitable for most LEDs if your supply voltage is 12V or less Remember to connect the LED the correct way round
Sizes Shapes and Viewing angles of LEDs
LEDs are available in a wide variety of sizes and shapes The standard LED has a round cross-section of 5mm diameter and this is probably the best type for general use but 3mm round LEDs are also popular
Round cross-section LEDs are frequently used and they are very easy to install on boxes by drilling a hole of the LED diameter adding a spot of glue will help to hold the LED if necessary LED clips are also available to secure LEDs in holes Other cross-section shapes include square rectangular and triangular
As well as a variety of colours sizes and shapes LEDs also vary in their viewing angle This tells you how much the beam of light spreads out Standard LEDs have a viewing angle of 60deg but others have a narrow beam of 30deg or less
Calculating an LED resistor value
An LED must have a resistor connected in series to limit the current through the LED otherwise it will burn out almost instantly
The resistor value R is given by
R = (VS - VL) I
VS = supply voltage VL = LED voltage (usually 2V but 4V for blue and white LEDs) I = LED current (eg 20mA) this must be less than the maximum permitted
If the calculated value is not available choose the nearest standard resistor value which is greater so that the current will be a little less than you chose In fact you may wish to choose a greater resistor value to reduce the current (to increase battery life for example) but this will make the LED less bright
Working out the LED resistor formula using Ohms law
Ohms law says that the resistance of the resistor R = VI where V = voltage across the resistor (= VS - VL in this case) I = the current through the resistor
So R = (VS - VL) I
BUZZERS
A buzzer or beeper (BUZZERS) is a signalling device usually electronic typically used in automobiles household appliances such as a microwave oven or game shows It most commonly consists of a number of switches or sensors connected to a control unit that determines if and which button was pushed or a preset time has lapsed and usually illuminates a light on the appropriate button or control panel and sounds a warning in the form of a continuous or intermittent buzzing
or beeping sound Initially this device was based on an electromechanical system which was identical to an electric bell without the metal gong (which makes the ringing noise) Often these units were anchored to a wall or ceiling and used the ceiling or wall as a sounding board Another implementation with some AC-connected devices was to implement a circuit to make the AC current into a noise loud enough to drive a loudspeaker and hook this circuit up to a cheap 8-ohm speaker Nowadays it is more popular to use a ceramic-based piezoelectric sounder which makes a high-pitched tone Usually these were hooked up to driver circuits which varied the pitch of the sound or pulsed the sound on and off
The word buzzer comes from the rasping noise that buzzers made when they were electromechanical devices operated from stepped-down AC line voltage at 50 or 60 cycles Other sounds commonly used to indicate that a button has been pressed are a ring or a beep
MOTORS
An electric motor is a device using electrical energy to produce mechanical energy nearly always by the interaction of magnetic fields and current-carrying conductors The reverse process that of using mechanical energy to produce electrical energy is accomplished by a generator or dynamo Traction motors used on vehicles often perform both tasks
Electric motors are found in myriad uses such as industrial fans blowers and pumps machine tools household appliances power tools and computer disk drives among
many other applications Electric motors may be operated by direct current from a battery in a portable device or motor vehicle or from alternating current from a central electrical distribution grid The smallest motors may be found in electric wristwatches Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses The very largest electric motors are used for propulsion of large ships and for such purposes as pipeline compressors with ratings in the thousands of kilowatts Electric motors may be classified by the source of electric power by their internal construction and by application
The physical principle of production of mechanical force by the interaction of an electric current and a magnetic field was known as early as 1821 Electric motors of increasing efficiency were constructed throughout the 19th century but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks
CONNECTORS
A DC connector is an electrical connector for
supplying direct current (DC) power DC connectors
are poorly standardized compared to domestic AC
power plugs and sockets DC plug is a common name
used for one common type of cylindrical two-conductor
plug available in a range of sizes and used to power
small pieces of electronic equipment It is also used to
describe some older multi-pin plugs
Several competing standards exist for DC plugs and in some cases incompatible plugs
will fit together to avoid damaging equipment these conditions must be true
Voltage must match
Polarity is correct
Current ratings are sufficient
Power supply filtering and stability is adequate
for the equipment being powered
Non-matching connectors are forced together
12V DC BATTERY
Features
Less than a 12 volt self discharge per 6 months 4 ea 12Vdc outputs 20 AmpHours Built-charger Digital Voltmeter
Description
This unit supplies a full 12Vdc at 20 AmpHours Designed for the officer that needs a power source that can be charged from 115Ac source or on the way to a incident from the car
The battery source has a very low self discharge rate which makes it perfect for law enforcement use The battery can set on the shelf for more than 6 months without recharging
Everyone knows when you grab a battery operated device the internal battery always requires several hours of charging before using The new voltage indicator reads out voltage to one hundredth of a volt for accurate operation The four outputs are 21mm plug Quick terminals and Cigarette lighter jack amp PT02 (Mil Spec) This model also allows powering
12Vdc sources while plugged in to 115Vac ldquoIts a UPSrdquo
SPECIFICATIONS OF COMPONENTS USED
PLC S7-200
INPUT POWER 230V AC 50 Hz
INPUTS 24 DC INPUTS
OUTPUTS 16 DC OUTPUTS
PROGRAM MEMORY 24
DATA MEMORY 10KB
EXPANSION MODULES 7
COMMUNICATION PORTS 2 RS 485
DIGITAL IO IMAGE SIZE 256(128 in 128 out)
EXECUTION SPEED 022microsecondsinstruction
SENSORS
SENSING RANGE 3mm
HOUSING MATERIAL Brass Nickel Plated
OPERATING VOLTAGE 10-30V
OPERATING CURRENT lt200mA
CONNECTION TYPE Cable
LEDS
DIAMETER 5mm
MAXIMUM VOLTAGE 1V
MAXIMUM CURRENT 10mA
INTENSITY
BUZZERS
OPERATING VOLTAGE30Vp-p
RATED FREQUENCY2000Hz 500Hz
OPERATING TEMP RANGE -20 to 60 degree
SOUND OUTPUT70 dB min10 cm
MOTOR
TOTAL LENGTH 46mm MOTOR DIAMETER 36mm MOTOR LENGTH 25mm DC SUPPLY 4 to 12V RPM 100 BRUSH TYPE Precious metal GEAR HEAD DIAMETER 37mm GEAR HEAD LENGTH 21mm OUTPUT SHAFT Centered SHAFT DIAMETER 4mm and 6mm
SHAFT LENGTH 22mm
- Block diagram of plc
- Applications
-
- Function
- Testing an LED
- Sizes Shapes and Viewing angles of LEDs
- Calculating an LED resistor value
-
- Working out the LED resistor formula using Ohms law
-
We take the opportunity to thank one and all who have helped us in making this project successful We are extremely happy to present this project under the esteemed guidance of Prof P Sri Hari Head of department Department of Electronics and Communication Engineering
We are grateful to Prof PSri Hari HOD Electronics and Communication Engineering VNRVJIET for his encouragement for carrying out this project
We would also like to thank all the staff members of ECE department for their help and kind support in times of need
Finally our humble thanks to the almighty but for whom we did none
ACKNOWLEDGEMENT
We owe our profound acknowledgement to all those people who made this
project successful We present the names of those people to whom we are very much
grateful We would like to express our most sincere thanks to all those people who are
involved in our project work Any omissions are regretted We express our deep sense
of gratitude to Automation Solutions KPHB Hyderabad for permitting us to work in their
organization
We express our special gratitude and thanks to MrManohar CEO Automation
Solutions Hyderabad for his kind co-operation without whom the project training would
not have been completed
We would like to express our humble and sincere thanks to MsNeelima
Automation Solutions Hyderabad for her encouragement and constant support
throughout the training
We take the opportunity to thank our Head of Department Prof PSri Hari for his
timely advice and guidance while pursuing this project as well as throughout the BTech
course Our sincere thanks to our beloved professor and internal guide for his guidance
and contribution in developing the project
ABSTRACT
In this fast developing science revolutionary era automation of an industry has become a necessity A PLC (Programmable Logic Controller) is a programmable system used for automation The Programmable Logic Controller may be defined as ldquoA PLC is a microprocessor based specialized computer that carries out the control functions of many types and levels of complexityrdquo
A PLC has many input terminals through which it interprets high and low logical states from sensors and switches It also has many output terminals through which it outputs high and low signals to power lights solenoids contactors small motors and other devices lending themselves to onoff control
We have designed a kit for automating a car parking guidance system For this a PLC (Siemens S7-200) has been used The PLC has been pre-programmed and is the brain of the system It reads the inputs from the various sensors and makes logical decisions These logical decisions are given to the PLC by using a suitable programming language Accordingly the necessary operation is carried out Our project illustrates only a simple application of the PLC while the PLC is a powerful tool the applications of which are innumerable and complex
PLATFORM S7-200 PLC
PROGRAMMING LANGUAGE LADDER DIAGRAMS
SOFTWARE S7 MICROWIN
KEYWORDS SENSORS BUZZERS LEDS AUTOMATION
LADDER LOGIC MEMORY
1 INTRODUCTION
A programmable logic controller (PLC) or programmable controller is a digital computer used for automation of electromechanical processes such as control of machinery on factory assembly lines amusement rides or lighting fixtures PLCs are
used in many industries and machines such as packaging and semiconductor machines Unlike general-purpose computers the PLC is designed for multiple inputs and output arrangements extended temperature ranges immunity to electrical noise and resistance to vibration and impact Programs to control machine operation are typically stored in battery-backed or non-volatile memory A PLC is an example of a real time system since output results must be produced in response to input conditions within a bounded time otherwise unintended operation will result
A PLC has many input terminals through which it interprets high and low logical states from sensors and switches It also has many output terminals through which it outputs high and low signals to power lights solenoids contactors small motors and other devices lending themselves to onoff control In an effort to make PLCs easy to program their programming language was designed to resemble ladder logic diagrams Thus an industrial electrician or electrical engineer accustomed to reading ladder logic schematics would feel comfortable programming a PLC to perform the same control functions
PLCs are industrial computers and as such their input and output signals are typically 120 volts AC just like the electromechanical control relays they were designed to replace Although some PLCs have the ability to input and output low-level DC voltage signals of the magnitude used in logic gate circuits this is the exception and not the rule
The actual logic of the control system is established inside the PLC by means of a computer program This program dictates which output gets energized under which input conditions Although the program itself appears to be a ladder logic diagram with switch and relay symbols there are no actual switch contacts or relay coils operating inside the PLC to create the logical relationships between input and output These are imaginary contacts and coils if you will The program is entered and viewed via a personal computer connected to the PLCs programming port
The true power and versatility of a PLC is revealed when we want to alter the behavior of a control system Since the PLC is a programmable device we can alter its behavior by changing the commands we give it without having to reconfigure the electrical components connected to it
One of the advantages of implementing logical control in software rather than in hardware is that input signals can be re-used as many times in the program as is necessary Another advantage of PLCs that simply cannot be duplicated by electromechanical relays is remote monitoring and control via digital computer networks Because a PLC is nothing more than a special-purpose digital computer it has the ability to communicate with other computers rather easily
2 HISTORY
21 ORIGIN
The PLC was invented in response to the needs of the American automotive manufacturing industry Programmable controllers were initially adopted by the automotive industry where software revision replaced the re-wiring of hard-wired control panels when production models changed
Before the PLC control sequencing and safety interlock logic for manufacturing automobiles was accomplished using hundreds or thousands of relays cam timers and drum sequencers and dedicated closed-loop controllers The process for updating such facilities for the yearly model change-over was very time consuming and expensive as the relay systems needed to be rewired by skilled electricians
In 1968 GM Hydramatic (the automatic transmission division of General Motors) issued a request for proposal for an electronic replacement for hard-wired relay systems
The winning proposal came from Bedford Associates of Bedford Massachusetts The first PLC designated the 084 because it was Bedford Associates eighty-fourth project was the result Bedford Associates started a new company dedicated to developing manufacturing selling and servicing this new product MODICON which stood for MOdular DIgital CONtroller One of the people who worked on that project was Dick Morley who is considered to be the father of the PLC The MODICON brand was sold in 1977 to Gould Electronics and later acquired by German Company AEG and then by French Schneider Electric the current owner
One of the very first 084 models built is now on display at Modicons headquarters in North Andover Massachusetts It was presented to Modicon by GM when the unit was retired after nearly twenty years of uninterrupted service Modicon used the 84 moniker at the end of its product range until the 984 made its appearance
The automotive industry is still one of the largest users of PLCs
22 DEVELOPMENT
Early PLCs were designed to replace relay logic systems These PLCs were programmed in ladder logic which strongly resembles a schematic diagram of relay logic Modern PLCs can be programmed in a variety of ways from ladder logic to more traditional programming languages such as BASIC and C Another method is State Logic a very high-level programming language designed to program PLCs based on state transition diagrams
Many of the earliest PLCs expressed all decision making logic in simple ladder logic which appeared similar to electrical schematic diagrams This program notation was chosen to reduce training demands for the existing technicians Other early PLCs used a form of instruction list programming based on a stack-based logic solver
23 PROGRAMMING
Early PLCs up to the mid-1980s were programmed using proprietary programming panels or special-purpose programming terminals which often had dedicated function keys representing the various logical elements of PLC programs Programs were stored on cassette tape cartridges Facilities for printing and documentation were very minimal due to lack of memory capacity The very oldest PLCs used non-volatile magnetic core memory
24 FUNCTIONALITY
The functionality of the PLC has evolved over the years to include sequential relay control motion control process control distributed control systems and networking The data handling storage processing power and communication capabilities of some modern PLCs are approximately equivalent to desktop computers PLC-like programming combined with remote IO hardware allow a general-purpose desktop computer to overlap some PLCs in certain applications
PLC ARCHITECTURE
CPU
Power Supply
Memory
Input Blocks
Output Blocks
Communications
Expansion Connections
BLOCK DIAGRAM OF PLC
SENSORS
PLC COMPARED WITH OTHER CONTROL SYSTEMS
PLCs are well-adapted to a range of automation tasks These are typically industrial processes in manufacturing where the cost of developing and maintaining the automation system is high relative to the total cost of the automation and where changes to the system would be expected during its operational life PLCs contain input and output devices compatible with industrial pilot devices and controls little electrical design is required and the design problem centers on expressing the desired sequence of operations in ladder logic (or function chart) notation PLC applications are typically highly customized systems so the cost of a packaged PLC is low compared to the cost of a specific custom-built controller design On the other hand in the case of mass-produced goods customized control systems are economic due to the lower cost of the components which can be optimally chosen instead of a generic solution and where the non-recurring engineering charges are spread over thousands or millions of units
For high volume or very simple fixed automation tasks different techniques are used A microcontroller-based design would be appropriate where hundreds or thousands of units will be produced and so the development cost (design of power supplies and inputoutput hardware) can be spread over many sales and where the end-user would not need to alter the control Automotive applications are an example millions of units are built each year and very few end-users alter the programming of these controllers
Power supply
Input
Module
Memory
Processor
Output
Module
However some specialty vehicles such as transit busses economically use PLCs instead of custom-designed controls because the volumes are low and the development cost would be uneconomic
Very complex process control such as used in the chemical industry may require algorithms and performance beyond the capability of even high-performance PLCs Very high-speed or precision controls may also require customized solutions for example aircraft flight controls
Programmable controllers are widely used in motion control positioning control and torque control Some manufacturers produce motion control units to be integrated with PLC so that G-code (involving a CNC machine) can be used to instruct machine movements
PLCs may include logic for single-variable feedback analog control loop a proportional integral derivative or PID controller A PID loop could be used to control the temperature of a manufacturing process for example Historically PLCs were usually configured with only a few analog control loops where processes required hundreds or thousands of loops a distributed control system (DCS) would instead be used As PLCs have become more powerful the boundary between DCS and PLC applications has become less distinct
PLCs have similar functionality as Remote Terminal Units An RTU however usually does not support control algorithms or control loops As hardware rapidly becomes more powerful and cheaper RTUs PLCs and DCSs are increasingly beginning to overlap in responsibilities The industry has standardized on the IEC 61131-3 functional block language for creating programs to run on RTUs and PLCs although nearly all vendors also offer proprietary alternatives and associated development environments
DISADVANTAGES OF lsquoHARD WIRED LOGIC CONTROLrsquo
Bulky panels
Complex wiring
Longer project time
Difficult maintenance and troubleshooting
ADVANTAGES OF lsquoPLCSrsquo
Reduced space
Ease of maintenance
Economical
Greater life amp reliability
Tremendous flexibility
Shorter project time
Easier storage archiving and documentation
WHAT CONSTITUTES A PLC
The PLC is programmed interface between the Input field elements amp output field
elements
PLC consist of
Hardware
Input Module
CPU (Central Process Unit)
Program memory
Output module
Power Supply
Software
Application Software (Logic)
Basic Software
Communication Accessories
Communication Adapter
INPUT-OUTPUT
Input and output (IO) modules connect the PLC to
sensors and actuators
Provide isolation for the low-voltage low-current
signals
Wide range of IO modules available including
Digital (logical) IO modules and Analogue (continuous) IO modules
Analogue input cards convert continuous signals via an AD converter into discrete
values for the PLC
Analogue output cards convert digital values in then PLC to continuous signals via a
DA converter
Resolution can be important in choosing an applicable card
Module receptacle for battery EEPROM
CPU statu
s LEDrsquo
sCommunicatio
ns interfa
ce
Status LEDrsquos of
the inputs
and outputs
Fixing holes for wall
mounting
Locking clip for DIN rail mounting
Analog potentiometer
Removable
connection
terminals(on 224 226)
Example for a temperature input of 0 to 100 degrees C
For 8 bit resolution the value in the PLC is 0 to 255
For 12 bit resolution the value in the PLC is 0 to 4095
For 16 bit resolution the value in the PLC is 0 to 32768
SPECIAL MODULES
RF ID
Modem modules
Load Cell
Stepper Modules
Temperature Sensor
High Speed Counters
Position Control Cards
Field Bus Cards
o Device Net Profibus Ethernet etc
ELEMENTS OF INPUTS
Digital Inputs
push button
limit switches
Sensors
o Proximity Sensors
o Photo Sensors
Micro Switches
Toggle Switches
Analog Inputs
Pressure Transmitters
Flow Transmitter
Level Transmitter
Thermo Couples
Load Cell
ELEMENTS OF OUTPUTS
Digital Outputs
Relays
Contactors
Indication Lamps
Valves
Analog Outputs
Flow Control Valves
Pressure Control Valves
Drive Inputs
BASIC ELEMENTS OF A PROGRAM
A program block is composed of executable code and comments The executable codes consist of a main program and any subroutines or interrupt routines The code is compiled and downloaded to the S7-200 the program comments are not You can use the organizational elements (main program subroutines and interrupt routines) to structure your control program
Main ProgramThe main body of the program contains the instructions that control your application The S7-200 executes these instructions sequentially once per scan cycle The main program is also referred to as OB1
SubroutinesThese optional elements of your program are executed only when called by the main program by an interrupt routine or by another subroutine Subroutines are useful in cases where you want to execute a function repeatedly Rather than rewriting the logic for each place in the main program where you want the function to occur you can write the logic once in a subroutine and call the subroutine as many times as needed during the main program Subroutines provide several benefits
1048600 Using subroutines reduces the overall size of your program 1048600 Using subroutines decreases your scan time because you have moved the code out of the main program The S7-200 evaluates the code in the main program every scan cycle whether the code is executed or not but the S7-200 evaluates the code in the subroutine only when you call the subroutine and does not evaluate the code during the scans in which the subroutine is not called 1048600 Using subroutines creates code that is portable You can isolate the code for a function in a subroutine and then copy that subroutine into other programs with Interrupt RoutinesThese optional elements of your program react to specific interrupt events You design an interrupt routine to handle a pre-defined interrupt event Whenever the specified event occurs the S7-200 executes the interrupt routineThe interrupt routines are not called by your main program You associate an interrupt routine with an interrupt event and the S7-200 executes the instructions in the interrupt routine only on each occurrence of the interrupt event Other Elements of the ProgramOther blocks contain information for the S7-200 You can choose to download these blocks when you download your programSystem BlockThe system block allows you to configure different hardware options for the S7-200Data BlockThe data block stores the values for different variables (V memory) used by your program You can use the data block to enter initial values for the data
PROGRAMMING LANGUAGES IN PLC
IL (Instruction List) ndash mnemonic programming
LD (Ladder Diagram) ndash Relay logic
ST (Structured Text) ndash A C like programming language
FDB (Functional Block Diagram) ndash Graphical dataflow programming language
SFC (Sequential Flow Chart) ndash Graphical method for structured programs
Basic PLC Memory
Memory on a PLC is separated into 3 main areas
LOAD Memory
Can be RAM (dynamic) or EEPROM (retentive)
Used to store user programs
WORK Memory
Memory is RAM
When PLC starts Program is copied from LOAD memory to
WORK memory The program is then executed from Work
memory
SYSTEM Memory
Memory is RAM
Is used by micro-controller to implement counters timers interrupt
stacks etc
Contains a bit for each D I0
Contains ldquoMarker Memoryrdquo Marker memory is a free area of RAM
that can be used by the programmer
Contains ldquoProcess Input and Output Imagesrdquo Periodically the PLC
will store the states of the inputs to the Process Input Image and
Process Output Image to the output
SELECTION OF A PLC
Selection of PLC Based on
No of Inputs amp Outputs
Input Voltage
Memory
Scan Time
Special IO modules
Expansion Capabilities
Stand alone or Networked
Communication Capabilities
HOW PLC WORKS
Step 1-CHECKING INPUT STATUS
o PLC Scans each input
o Records the data in work memory
Step 2-EXECUTE PROGRAM
o PLC goes through the program logic step by step
o PLC executes the program depending on input status
o Write the output image in work memory
Step 3-UPDATE OUTPUT STATUS
o Changes the statues of the output onoff
o Again starts the cycle from step one
FEATURES OF S7-200
Allows Your Program to Immediately Read or Write the IO
Allows Your Program to Interrupt the Scan Cycle
Allows You to Allocate Processing Time for Communications
Tasks
Allows You to Set the States of Digital Outputs for Stop
CHECK
INPUT STATUS
EXECUTE
PROGRAM
UPDATE
OUTPUT STATUS
Mode
Allows You to Define Memory to Be Retained on Loss of Power
Allows You to Filter the Digital Inputs
Allows You to Filter the Analog Inputs
Allows You to Catch Pulses of Short Duration
Provides Password Protection
Provides Analog Adjustment Potentiometers
Provides High-speed IO
TECHNICAL FEATURES OF S7-200
Several models of CPUrsquos
o CPU 221 6in4out 2Kw program
o CPU 222 8in6out 2Kw program
o CPU 224 14in10out 4Kw program
o CPU 226 24in16out 4Kw program
Up to 256 digital input-outputs
Up to 32 analog channels
256 timers 256 counters
Built-in EEPROM memory
Real-time clockcalendar
Built-in communications
Password protection
Memory module
Removable input-output connectors
Wide range of expansion modules
o 8 pt input and output
o 4488 amp1616 inout combination
o 4 channel analog in 2 channel analog out
o 4 ch1ch analog inout combination
o 2 channel RTD in
o 4 channel thermocouple in
o PROFIBUS-DP Slave
o AS Interface master
SELECTING THE OPERATING MODE FOR THE S7- 200 CPU
The S7-200 has two modes of operation STOP mode and RUN mode The status LED on the front of the CPU indicates the current mode of operation In STOP mode the S7-200 is not executing the program and you can download a program or the CPU configuration In RUN mode the S7-200 is running the program
1048600 The S7-200 provides a mode switch for changing the mode of operation You can use the mode switch (located under the front access door of the S7-200) to manually select the operating mode setting the mode switch to STOP mode stops the execution of the program setting the mode switch to RUN mode starts the execution of the program and setting the mode switch to TERM (terminal) mode does not change the operating mode
If a power cycle occurs when the mode switch is set to either STOP or TERM the
S7-200 goes automatically to STOP mode when power is restored If a power cycle occurs when the mode switch is set to RUN the S7-200 goes to RUN mode when power is restored
1048600 STEP 7--MicroWIN allows you to change the operating mode of the online S7-200 To enable the software to change the operating mode you must manually set the mode switch on the S7-200 to either TERM or RUN You can use the PLC gt STOP or PLC gt RUN menu commands or the associated buttons on the toolbar to change the operating mode
1048600 You can insert the STOP instruction in your program to change the S7-200 to STOP mode This allows you to halt the execution of your program based on the program logic
ERRORS IN S7-200
Non-Fatal Errors
Non-fatal errors are those indicating problems with the construction of the user program with the execution of an instruction in the user program and with expansion IO modules You can use STEP 7--MicroWIN to view the error codes that were generated by the non-fatal error There are three basic categories of non-fatal errors
Program-compile errorsThe S7-200 compiles the program as it downloads If the S7-200 detects that the program violates a compilation rule the download is aborted and an error code is generated (A program that was already downloaded to the S7-200 would still exist in the EEPROM and would not be lost) After you correct your program you can download it again
IO errorsAt startup the S7-200 reads the IO configuration from each module During normal operation the S7-200 periodically checks the status of each module and compares it against the configuration obtained during startup If the S7-200 detects a difference the S7-200 sets the configuration error bit in the module error register The S7-200 does not read input data from or write output data to that module until the module configuration again matches the one obtained at startupThe module status information is stored in special memory (SM) bits Your program can monitor and evaluate these bits Refer to Appendix D for more information about the SM bits used for reporting IO errors SM50 is the global IO error bit and remains set while an error condition exists on an expansion module
Program execution errorsYour program can create error conditions while being executed These errors can result from improper use of an instruction or from the processing of invalid data by an instruction For example an indirect-address pointer that was valid when the program compiled could be modified during the execution of the program to point to an out-of-range address This is an example of a run-time programming problem SM43 is setupon the occurrence of a run-time programming problem and remains set while the S7-200 is in RUN mode Program execution error information is stored in special memory (SM) bits Your program can monitor and evaluate these bits The S7-200 does not change to STOP mode when it detects a non-fatal error It only logs the event in SM memory and continues with the execution of your program However you can design your program to force the S7-200 to STOP mode when a non-fatal error is detected
Fatal Errors
Fatal errors cause the S7-200 to stop the execution of your program Depending upon the severity of the fatal error it can render the S7-200 incapable of performing any or all functions The objective for handling fatal errors is to bring the S7-200 to a safe state from which the S7-200 can respond to interrogations about the existing error conditions When a fatal error is detected the S7-200 changes to STOP mode turns on the System Fault LED and the STOP LED overrides the output table and turns off the outputsThe S7-200 remains in this condition until the fatal error condition is corrected
Once you have made the changes to correct the fatal error condition use one of the following methods to restart the S7-200 1048600 Turn the power off and then on 1048600 Change the mode switch from RUN or TERM to STOP 1048600 Select the PLC gt Power-Up Reset menu command from STEP 7--MicroWIN
to restart the S7-200This forces the S7-200 to restart and clear any fatal errors
Restarting the S7-200 clears the fatal error condition and performs power-up diagnostic testing to verify that the fatal error has been corrected If another fatal error condition is found the S7-200 again sets the fault LED indicating that an error still exists Otherwise the S7-200 begins normal operation
Some error conditions can render the S7-200 incapable of communication In these cases you cannot view the error code from the S7-200 These types of errors indicate hardware failures that require the S7-200 to be repaired they cannot be fixed by changes to the program or clearing the memory of the S7-200
APPLICATIONS OF S7-200
Conveyer Systems
Elevators
Test Stations
Placement Systems
Woodworking Machinery
Packaging Equipment
Car Wash Automation
Remote Monitoring And Controlling For Water Wastewater
FEATURES OF LADDER DIAGRAMS
The LAD editor displays the program as a graphical representation similar to electrical wiring diagrams
Ladder programs allow the program to emulate the flow of electric current from a power source through a series of logical input conditions that in turn enable logical output conditions
A LAD program includes a left power rail that is energized Contacts that are closed allow energy to flow through them to the next element and contacts that are open block that energy flow
The logic is separated into networks The program is executed one network at a time from left to right and then top to bottom as dictated by the program Figure shows an example of a LAD program
The various instructions are represented by graphic symbols and include three basic forms
Contacts represent logic input conditions such as switches buttons or internal conditions
Coils usually represent logic output results such as lamps motor starters interposing relays or internal output conditions
Boxes represent additional instructions such as timers counters or math instructions Figure Sample LAD Program
Consider these main points when you select the LAD editor 1048600 Ladder logic is easy for beginning programmers to use 1048600 Graphical representation is easy to understand and is popular around the world 1048600 The LAD editor can be used with both the SIMATIC and IEC 1131--3 Instruction sets
1048600 You can always use the STL editor to display a program created with
the SIMATIC LAD editor
COMPONENTS LIST
Cardboard of 4050 sqcm
PLC S7-200
Sensors
LEDS
Buzzers
Motor
Contactors
Power supply
12v DC battery
Connecting wires
PPI Cable
SENSORS
A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact A proximity sensor often emits an electromagnetic or electrostatic field or a beam of electromagnetic radiation (infrared for instance) and looks for changes in the field or return signal The object being sensed is often referred to as the proximity sensors target Different
proximity sensor targets demand different sensors For example a capacitive or photoelectric sensor might be suitable for a plastic target an inductive proximity sensor requires a metal target
The maximum distance that this sensor can detect is defined nominal range Some sensors have adjustments of the nominal range or means to report a graduated detection distance
Proximity sensors can have a high reliability and long functional life because of the absence of mechanical parts and lack of physical contact between sensor and the sensed object
IEC 60947-5-2 defines the technical details of proximity sensors
A proximity sensor adjusted to a very short range is often used as a touch switch
Applications
Car bumpers that sense distance to nearby cars for parking
Ground proximity warning system for aviation safety Vibration Position measurements of rotating shafts in
machinery Sheet break sensing in paper machine Anti-aircraft artillery
LEDS
Example Circuit symbol
FunctionLEDs emit light when an electric current passes through them
Testing an LED
Never connect an LED directly to a battery or power supply
LEDs must have a resistor in series to limit the current to a safe value for quick testing purposes a 1k resistor is suitable for most LEDs if your supply voltage is 12V or less Remember to connect the LED the correct way round
Sizes Shapes and Viewing angles of LEDs
LEDs are available in a wide variety of sizes and shapes The standard LED has a round cross-section of 5mm diameter and this is probably the best type for general use but 3mm round LEDs are also popular
Round cross-section LEDs are frequently used and they are very easy to install on boxes by drilling a hole of the LED diameter adding a spot of glue will help to hold the LED if necessary LED clips are also available to secure LEDs in holes Other cross-section shapes include square rectangular and triangular
As well as a variety of colours sizes and shapes LEDs also vary in their viewing angle This tells you how much the beam of light spreads out Standard LEDs have a viewing angle of 60deg but others have a narrow beam of 30deg or less
Calculating an LED resistor value
An LED must have a resistor connected in series to limit the current through the LED otherwise it will burn out almost instantly
The resistor value R is given by
R = (VS - VL) I
VS = supply voltage VL = LED voltage (usually 2V but 4V for blue and white LEDs) I = LED current (eg 20mA) this must be less than the maximum permitted
If the calculated value is not available choose the nearest standard resistor value which is greater so that the current will be a little less than you chose In fact you may wish to choose a greater resistor value to reduce the current (to increase battery life for example) but this will make the LED less bright
Working out the LED resistor formula using Ohms law
Ohms law says that the resistance of the resistor R = VI where V = voltage across the resistor (= VS - VL in this case) I = the current through the resistor
So R = (VS - VL) I
BUZZERS
A buzzer or beeper (BUZZERS) is a signalling device usually electronic typically used in automobiles household appliances such as a microwave oven or game shows It most commonly consists of a number of switches or sensors connected to a control unit that determines if and which button was pushed or a preset time has lapsed and usually illuminates a light on the appropriate button or control panel and sounds a warning in the form of a continuous or intermittent buzzing
or beeping sound Initially this device was based on an electromechanical system which was identical to an electric bell without the metal gong (which makes the ringing noise) Often these units were anchored to a wall or ceiling and used the ceiling or wall as a sounding board Another implementation with some AC-connected devices was to implement a circuit to make the AC current into a noise loud enough to drive a loudspeaker and hook this circuit up to a cheap 8-ohm speaker Nowadays it is more popular to use a ceramic-based piezoelectric sounder which makes a high-pitched tone Usually these were hooked up to driver circuits which varied the pitch of the sound or pulsed the sound on and off
The word buzzer comes from the rasping noise that buzzers made when they were electromechanical devices operated from stepped-down AC line voltage at 50 or 60 cycles Other sounds commonly used to indicate that a button has been pressed are a ring or a beep
MOTORS
An electric motor is a device using electrical energy to produce mechanical energy nearly always by the interaction of magnetic fields and current-carrying conductors The reverse process that of using mechanical energy to produce electrical energy is accomplished by a generator or dynamo Traction motors used on vehicles often perform both tasks
Electric motors are found in myriad uses such as industrial fans blowers and pumps machine tools household appliances power tools and computer disk drives among
many other applications Electric motors may be operated by direct current from a battery in a portable device or motor vehicle or from alternating current from a central electrical distribution grid The smallest motors may be found in electric wristwatches Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses The very largest electric motors are used for propulsion of large ships and for such purposes as pipeline compressors with ratings in the thousands of kilowatts Electric motors may be classified by the source of electric power by their internal construction and by application
The physical principle of production of mechanical force by the interaction of an electric current and a magnetic field was known as early as 1821 Electric motors of increasing efficiency were constructed throughout the 19th century but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks
CONNECTORS
A DC connector is an electrical connector for
supplying direct current (DC) power DC connectors
are poorly standardized compared to domestic AC
power plugs and sockets DC plug is a common name
used for one common type of cylindrical two-conductor
plug available in a range of sizes and used to power
small pieces of electronic equipment It is also used to
describe some older multi-pin plugs
Several competing standards exist for DC plugs and in some cases incompatible plugs
will fit together to avoid damaging equipment these conditions must be true
Voltage must match
Polarity is correct
Current ratings are sufficient
Power supply filtering and stability is adequate
for the equipment being powered
Non-matching connectors are forced together
12V DC BATTERY
Features
Less than a 12 volt self discharge per 6 months 4 ea 12Vdc outputs 20 AmpHours Built-charger Digital Voltmeter
Description
This unit supplies a full 12Vdc at 20 AmpHours Designed for the officer that needs a power source that can be charged from 115Ac source or on the way to a incident from the car
The battery source has a very low self discharge rate which makes it perfect for law enforcement use The battery can set on the shelf for more than 6 months without recharging
Everyone knows when you grab a battery operated device the internal battery always requires several hours of charging before using The new voltage indicator reads out voltage to one hundredth of a volt for accurate operation The four outputs are 21mm plug Quick terminals and Cigarette lighter jack amp PT02 (Mil Spec) This model also allows powering
12Vdc sources while plugged in to 115Vac ldquoIts a UPSrdquo
SPECIFICATIONS OF COMPONENTS USED
PLC S7-200
INPUT POWER 230V AC 50 Hz
INPUTS 24 DC INPUTS
OUTPUTS 16 DC OUTPUTS
PROGRAM MEMORY 24
DATA MEMORY 10KB
EXPANSION MODULES 7
COMMUNICATION PORTS 2 RS 485
DIGITAL IO IMAGE SIZE 256(128 in 128 out)
EXECUTION SPEED 022microsecondsinstruction
SENSORS
SENSING RANGE 3mm
HOUSING MATERIAL Brass Nickel Plated
OPERATING VOLTAGE 10-30V
OPERATING CURRENT lt200mA
CONNECTION TYPE Cable
LEDS
DIAMETER 5mm
MAXIMUM VOLTAGE 1V
MAXIMUM CURRENT 10mA
INTENSITY
BUZZERS
OPERATING VOLTAGE30Vp-p
RATED FREQUENCY2000Hz 500Hz
OPERATING TEMP RANGE -20 to 60 degree
SOUND OUTPUT70 dB min10 cm
MOTOR
TOTAL LENGTH 46mm MOTOR DIAMETER 36mm MOTOR LENGTH 25mm DC SUPPLY 4 to 12V RPM 100 BRUSH TYPE Precious metal GEAR HEAD DIAMETER 37mm GEAR HEAD LENGTH 21mm OUTPUT SHAFT Centered SHAFT DIAMETER 4mm and 6mm
SHAFT LENGTH 22mm
- Block diagram of plc
- Applications
-
- Function
- Testing an LED
- Sizes Shapes and Viewing angles of LEDs
- Calculating an LED resistor value
-
- Working out the LED resistor formula using Ohms law
-
We owe our profound acknowledgement to all those people who made this
project successful We present the names of those people to whom we are very much
grateful We would like to express our most sincere thanks to all those people who are
involved in our project work Any omissions are regretted We express our deep sense
of gratitude to Automation Solutions KPHB Hyderabad for permitting us to work in their
organization
We express our special gratitude and thanks to MrManohar CEO Automation
Solutions Hyderabad for his kind co-operation without whom the project training would
not have been completed
We would like to express our humble and sincere thanks to MsNeelima
Automation Solutions Hyderabad for her encouragement and constant support
throughout the training
We take the opportunity to thank our Head of Department Prof PSri Hari for his
timely advice and guidance while pursuing this project as well as throughout the BTech
course Our sincere thanks to our beloved professor and internal guide for his guidance
and contribution in developing the project
ABSTRACT
In this fast developing science revolutionary era automation of an industry has become a necessity A PLC (Programmable Logic Controller) is a programmable system used for automation The Programmable Logic Controller may be defined as ldquoA PLC is a microprocessor based specialized computer that carries out the control functions of many types and levels of complexityrdquo
A PLC has many input terminals through which it interprets high and low logical states from sensors and switches It also has many output terminals through which it outputs high and low signals to power lights solenoids contactors small motors and other devices lending themselves to onoff control
We have designed a kit for automating a car parking guidance system For this a PLC (Siemens S7-200) has been used The PLC has been pre-programmed and is the brain of the system It reads the inputs from the various sensors and makes logical decisions These logical decisions are given to the PLC by using a suitable programming language Accordingly the necessary operation is carried out Our project illustrates only a simple application of the PLC while the PLC is a powerful tool the applications of which are innumerable and complex
PLATFORM S7-200 PLC
PROGRAMMING LANGUAGE LADDER DIAGRAMS
SOFTWARE S7 MICROWIN
KEYWORDS SENSORS BUZZERS LEDS AUTOMATION
LADDER LOGIC MEMORY
1 INTRODUCTION
A programmable logic controller (PLC) or programmable controller is a digital computer used for automation of electromechanical processes such as control of machinery on factory assembly lines amusement rides or lighting fixtures PLCs are
used in many industries and machines such as packaging and semiconductor machines Unlike general-purpose computers the PLC is designed for multiple inputs and output arrangements extended temperature ranges immunity to electrical noise and resistance to vibration and impact Programs to control machine operation are typically stored in battery-backed or non-volatile memory A PLC is an example of a real time system since output results must be produced in response to input conditions within a bounded time otherwise unintended operation will result
A PLC has many input terminals through which it interprets high and low logical states from sensors and switches It also has many output terminals through which it outputs high and low signals to power lights solenoids contactors small motors and other devices lending themselves to onoff control In an effort to make PLCs easy to program their programming language was designed to resemble ladder logic diagrams Thus an industrial electrician or electrical engineer accustomed to reading ladder logic schematics would feel comfortable programming a PLC to perform the same control functions
PLCs are industrial computers and as such their input and output signals are typically 120 volts AC just like the electromechanical control relays they were designed to replace Although some PLCs have the ability to input and output low-level DC voltage signals of the magnitude used in logic gate circuits this is the exception and not the rule
The actual logic of the control system is established inside the PLC by means of a computer program This program dictates which output gets energized under which input conditions Although the program itself appears to be a ladder logic diagram with switch and relay symbols there are no actual switch contacts or relay coils operating inside the PLC to create the logical relationships between input and output These are imaginary contacts and coils if you will The program is entered and viewed via a personal computer connected to the PLCs programming port
The true power and versatility of a PLC is revealed when we want to alter the behavior of a control system Since the PLC is a programmable device we can alter its behavior by changing the commands we give it without having to reconfigure the electrical components connected to it
One of the advantages of implementing logical control in software rather than in hardware is that input signals can be re-used as many times in the program as is necessary Another advantage of PLCs that simply cannot be duplicated by electromechanical relays is remote monitoring and control via digital computer networks Because a PLC is nothing more than a special-purpose digital computer it has the ability to communicate with other computers rather easily
2 HISTORY
21 ORIGIN
The PLC was invented in response to the needs of the American automotive manufacturing industry Programmable controllers were initially adopted by the automotive industry where software revision replaced the re-wiring of hard-wired control panels when production models changed
Before the PLC control sequencing and safety interlock logic for manufacturing automobiles was accomplished using hundreds or thousands of relays cam timers and drum sequencers and dedicated closed-loop controllers The process for updating such facilities for the yearly model change-over was very time consuming and expensive as the relay systems needed to be rewired by skilled electricians
In 1968 GM Hydramatic (the automatic transmission division of General Motors) issued a request for proposal for an electronic replacement for hard-wired relay systems
The winning proposal came from Bedford Associates of Bedford Massachusetts The first PLC designated the 084 because it was Bedford Associates eighty-fourth project was the result Bedford Associates started a new company dedicated to developing manufacturing selling and servicing this new product MODICON which stood for MOdular DIgital CONtroller One of the people who worked on that project was Dick Morley who is considered to be the father of the PLC The MODICON brand was sold in 1977 to Gould Electronics and later acquired by German Company AEG and then by French Schneider Electric the current owner
One of the very first 084 models built is now on display at Modicons headquarters in North Andover Massachusetts It was presented to Modicon by GM when the unit was retired after nearly twenty years of uninterrupted service Modicon used the 84 moniker at the end of its product range until the 984 made its appearance
The automotive industry is still one of the largest users of PLCs
22 DEVELOPMENT
Early PLCs were designed to replace relay logic systems These PLCs were programmed in ladder logic which strongly resembles a schematic diagram of relay logic Modern PLCs can be programmed in a variety of ways from ladder logic to more traditional programming languages such as BASIC and C Another method is State Logic a very high-level programming language designed to program PLCs based on state transition diagrams
Many of the earliest PLCs expressed all decision making logic in simple ladder logic which appeared similar to electrical schematic diagrams This program notation was chosen to reduce training demands for the existing technicians Other early PLCs used a form of instruction list programming based on a stack-based logic solver
23 PROGRAMMING
Early PLCs up to the mid-1980s were programmed using proprietary programming panels or special-purpose programming terminals which often had dedicated function keys representing the various logical elements of PLC programs Programs were stored on cassette tape cartridges Facilities for printing and documentation were very minimal due to lack of memory capacity The very oldest PLCs used non-volatile magnetic core memory
24 FUNCTIONALITY
The functionality of the PLC has evolved over the years to include sequential relay control motion control process control distributed control systems and networking The data handling storage processing power and communication capabilities of some modern PLCs are approximately equivalent to desktop computers PLC-like programming combined with remote IO hardware allow a general-purpose desktop computer to overlap some PLCs in certain applications
PLC ARCHITECTURE
CPU
Power Supply
Memory
Input Blocks
Output Blocks
Communications
Expansion Connections
BLOCK DIAGRAM OF PLC
SENSORS
PLC COMPARED WITH OTHER CONTROL SYSTEMS
PLCs are well-adapted to a range of automation tasks These are typically industrial processes in manufacturing where the cost of developing and maintaining the automation system is high relative to the total cost of the automation and where changes to the system would be expected during its operational life PLCs contain input and output devices compatible with industrial pilot devices and controls little electrical design is required and the design problem centers on expressing the desired sequence of operations in ladder logic (or function chart) notation PLC applications are typically highly customized systems so the cost of a packaged PLC is low compared to the cost of a specific custom-built controller design On the other hand in the case of mass-produced goods customized control systems are economic due to the lower cost of the components which can be optimally chosen instead of a generic solution and where the non-recurring engineering charges are spread over thousands or millions of units
For high volume or very simple fixed automation tasks different techniques are used A microcontroller-based design would be appropriate where hundreds or thousands of units will be produced and so the development cost (design of power supplies and inputoutput hardware) can be spread over many sales and where the end-user would not need to alter the control Automotive applications are an example millions of units are built each year and very few end-users alter the programming of these controllers
Power supply
Input
Module
Memory
Processor
Output
Module
However some specialty vehicles such as transit busses economically use PLCs instead of custom-designed controls because the volumes are low and the development cost would be uneconomic
Very complex process control such as used in the chemical industry may require algorithms and performance beyond the capability of even high-performance PLCs Very high-speed or precision controls may also require customized solutions for example aircraft flight controls
Programmable controllers are widely used in motion control positioning control and torque control Some manufacturers produce motion control units to be integrated with PLC so that G-code (involving a CNC machine) can be used to instruct machine movements
PLCs may include logic for single-variable feedback analog control loop a proportional integral derivative or PID controller A PID loop could be used to control the temperature of a manufacturing process for example Historically PLCs were usually configured with only a few analog control loops where processes required hundreds or thousands of loops a distributed control system (DCS) would instead be used As PLCs have become more powerful the boundary between DCS and PLC applications has become less distinct
PLCs have similar functionality as Remote Terminal Units An RTU however usually does not support control algorithms or control loops As hardware rapidly becomes more powerful and cheaper RTUs PLCs and DCSs are increasingly beginning to overlap in responsibilities The industry has standardized on the IEC 61131-3 functional block language for creating programs to run on RTUs and PLCs although nearly all vendors also offer proprietary alternatives and associated development environments
DISADVANTAGES OF lsquoHARD WIRED LOGIC CONTROLrsquo
Bulky panels
Complex wiring
Longer project time
Difficult maintenance and troubleshooting
ADVANTAGES OF lsquoPLCSrsquo
Reduced space
Ease of maintenance
Economical
Greater life amp reliability
Tremendous flexibility
Shorter project time
Easier storage archiving and documentation
WHAT CONSTITUTES A PLC
The PLC is programmed interface between the Input field elements amp output field
elements
PLC consist of
Hardware
Input Module
CPU (Central Process Unit)
Program memory
Output module
Power Supply
Software
Application Software (Logic)
Basic Software
Communication Accessories
Communication Adapter
INPUT-OUTPUT
Input and output (IO) modules connect the PLC to
sensors and actuators
Provide isolation for the low-voltage low-current
signals
Wide range of IO modules available including
Digital (logical) IO modules and Analogue (continuous) IO modules
Analogue input cards convert continuous signals via an AD converter into discrete
values for the PLC
Analogue output cards convert digital values in then PLC to continuous signals via a
DA converter
Resolution can be important in choosing an applicable card
Module receptacle for battery EEPROM
CPU statu
s LEDrsquo
sCommunicatio
ns interfa
ce
Status LEDrsquos of
the inputs
and outputs
Fixing holes for wall
mounting
Locking clip for DIN rail mounting
Analog potentiometer
Removable
connection
terminals(on 224 226)
Example for a temperature input of 0 to 100 degrees C
For 8 bit resolution the value in the PLC is 0 to 255
For 12 bit resolution the value in the PLC is 0 to 4095
For 16 bit resolution the value in the PLC is 0 to 32768
SPECIAL MODULES
RF ID
Modem modules
Load Cell
Stepper Modules
Temperature Sensor
High Speed Counters
Position Control Cards
Field Bus Cards
o Device Net Profibus Ethernet etc
ELEMENTS OF INPUTS
Digital Inputs
push button
limit switches
Sensors
o Proximity Sensors
o Photo Sensors
Micro Switches
Toggle Switches
Analog Inputs
Pressure Transmitters
Flow Transmitter
Level Transmitter
Thermo Couples
Load Cell
ELEMENTS OF OUTPUTS
Digital Outputs
Relays
Contactors
Indication Lamps
Valves
Analog Outputs
Flow Control Valves
Pressure Control Valves
Drive Inputs
BASIC ELEMENTS OF A PROGRAM
A program block is composed of executable code and comments The executable codes consist of a main program and any subroutines or interrupt routines The code is compiled and downloaded to the S7-200 the program comments are not You can use the organizational elements (main program subroutines and interrupt routines) to structure your control program
Main ProgramThe main body of the program contains the instructions that control your application The S7-200 executes these instructions sequentially once per scan cycle The main program is also referred to as OB1
SubroutinesThese optional elements of your program are executed only when called by the main program by an interrupt routine or by another subroutine Subroutines are useful in cases where you want to execute a function repeatedly Rather than rewriting the logic for each place in the main program where you want the function to occur you can write the logic once in a subroutine and call the subroutine as many times as needed during the main program Subroutines provide several benefits
1048600 Using subroutines reduces the overall size of your program 1048600 Using subroutines decreases your scan time because you have moved the code out of the main program The S7-200 evaluates the code in the main program every scan cycle whether the code is executed or not but the S7-200 evaluates the code in the subroutine only when you call the subroutine and does not evaluate the code during the scans in which the subroutine is not called 1048600 Using subroutines creates code that is portable You can isolate the code for a function in a subroutine and then copy that subroutine into other programs with Interrupt RoutinesThese optional elements of your program react to specific interrupt events You design an interrupt routine to handle a pre-defined interrupt event Whenever the specified event occurs the S7-200 executes the interrupt routineThe interrupt routines are not called by your main program You associate an interrupt routine with an interrupt event and the S7-200 executes the instructions in the interrupt routine only on each occurrence of the interrupt event Other Elements of the ProgramOther blocks contain information for the S7-200 You can choose to download these blocks when you download your programSystem BlockThe system block allows you to configure different hardware options for the S7-200Data BlockThe data block stores the values for different variables (V memory) used by your program You can use the data block to enter initial values for the data
PROGRAMMING LANGUAGES IN PLC
IL (Instruction List) ndash mnemonic programming
LD (Ladder Diagram) ndash Relay logic
ST (Structured Text) ndash A C like programming language
FDB (Functional Block Diagram) ndash Graphical dataflow programming language
SFC (Sequential Flow Chart) ndash Graphical method for structured programs
Basic PLC Memory
Memory on a PLC is separated into 3 main areas
LOAD Memory
Can be RAM (dynamic) or EEPROM (retentive)
Used to store user programs
WORK Memory
Memory is RAM
When PLC starts Program is copied from LOAD memory to
WORK memory The program is then executed from Work
memory
SYSTEM Memory
Memory is RAM
Is used by micro-controller to implement counters timers interrupt
stacks etc
Contains a bit for each D I0
Contains ldquoMarker Memoryrdquo Marker memory is a free area of RAM
that can be used by the programmer
Contains ldquoProcess Input and Output Imagesrdquo Periodically the PLC
will store the states of the inputs to the Process Input Image and
Process Output Image to the output
SELECTION OF A PLC
Selection of PLC Based on
No of Inputs amp Outputs
Input Voltage
Memory
Scan Time
Special IO modules
Expansion Capabilities
Stand alone or Networked
Communication Capabilities
HOW PLC WORKS
Step 1-CHECKING INPUT STATUS
o PLC Scans each input
o Records the data in work memory
Step 2-EXECUTE PROGRAM
o PLC goes through the program logic step by step
o PLC executes the program depending on input status
o Write the output image in work memory
Step 3-UPDATE OUTPUT STATUS
o Changes the statues of the output onoff
o Again starts the cycle from step one
FEATURES OF S7-200
Allows Your Program to Immediately Read or Write the IO
Allows Your Program to Interrupt the Scan Cycle
Allows You to Allocate Processing Time for Communications
Tasks
Allows You to Set the States of Digital Outputs for Stop
CHECK
INPUT STATUS
EXECUTE
PROGRAM
UPDATE
OUTPUT STATUS
Mode
Allows You to Define Memory to Be Retained on Loss of Power
Allows You to Filter the Digital Inputs
Allows You to Filter the Analog Inputs
Allows You to Catch Pulses of Short Duration
Provides Password Protection
Provides Analog Adjustment Potentiometers
Provides High-speed IO
TECHNICAL FEATURES OF S7-200
Several models of CPUrsquos
o CPU 221 6in4out 2Kw program
o CPU 222 8in6out 2Kw program
o CPU 224 14in10out 4Kw program
o CPU 226 24in16out 4Kw program
Up to 256 digital input-outputs
Up to 32 analog channels
256 timers 256 counters
Built-in EEPROM memory
Real-time clockcalendar
Built-in communications
Password protection
Memory module
Removable input-output connectors
Wide range of expansion modules
o 8 pt input and output
o 4488 amp1616 inout combination
o 4 channel analog in 2 channel analog out
o 4 ch1ch analog inout combination
o 2 channel RTD in
o 4 channel thermocouple in
o PROFIBUS-DP Slave
o AS Interface master
SELECTING THE OPERATING MODE FOR THE S7- 200 CPU
The S7-200 has two modes of operation STOP mode and RUN mode The status LED on the front of the CPU indicates the current mode of operation In STOP mode the S7-200 is not executing the program and you can download a program or the CPU configuration In RUN mode the S7-200 is running the program
1048600 The S7-200 provides a mode switch for changing the mode of operation You can use the mode switch (located under the front access door of the S7-200) to manually select the operating mode setting the mode switch to STOP mode stops the execution of the program setting the mode switch to RUN mode starts the execution of the program and setting the mode switch to TERM (terminal) mode does not change the operating mode
If a power cycle occurs when the mode switch is set to either STOP or TERM the
S7-200 goes automatically to STOP mode when power is restored If a power cycle occurs when the mode switch is set to RUN the S7-200 goes to RUN mode when power is restored
1048600 STEP 7--MicroWIN allows you to change the operating mode of the online S7-200 To enable the software to change the operating mode you must manually set the mode switch on the S7-200 to either TERM or RUN You can use the PLC gt STOP or PLC gt RUN menu commands or the associated buttons on the toolbar to change the operating mode
1048600 You can insert the STOP instruction in your program to change the S7-200 to STOP mode This allows you to halt the execution of your program based on the program logic
ERRORS IN S7-200
Non-Fatal Errors
Non-fatal errors are those indicating problems with the construction of the user program with the execution of an instruction in the user program and with expansion IO modules You can use STEP 7--MicroWIN to view the error codes that were generated by the non-fatal error There are three basic categories of non-fatal errors
Program-compile errorsThe S7-200 compiles the program as it downloads If the S7-200 detects that the program violates a compilation rule the download is aborted and an error code is generated (A program that was already downloaded to the S7-200 would still exist in the EEPROM and would not be lost) After you correct your program you can download it again
IO errorsAt startup the S7-200 reads the IO configuration from each module During normal operation the S7-200 periodically checks the status of each module and compares it against the configuration obtained during startup If the S7-200 detects a difference the S7-200 sets the configuration error bit in the module error register The S7-200 does not read input data from or write output data to that module until the module configuration again matches the one obtained at startupThe module status information is stored in special memory (SM) bits Your program can monitor and evaluate these bits Refer to Appendix D for more information about the SM bits used for reporting IO errors SM50 is the global IO error bit and remains set while an error condition exists on an expansion module
Program execution errorsYour program can create error conditions while being executed These errors can result from improper use of an instruction or from the processing of invalid data by an instruction For example an indirect-address pointer that was valid when the program compiled could be modified during the execution of the program to point to an out-of-range address This is an example of a run-time programming problem SM43 is setupon the occurrence of a run-time programming problem and remains set while the S7-200 is in RUN mode Program execution error information is stored in special memory (SM) bits Your program can monitor and evaluate these bits The S7-200 does not change to STOP mode when it detects a non-fatal error It only logs the event in SM memory and continues with the execution of your program However you can design your program to force the S7-200 to STOP mode when a non-fatal error is detected
Fatal Errors
Fatal errors cause the S7-200 to stop the execution of your program Depending upon the severity of the fatal error it can render the S7-200 incapable of performing any or all functions The objective for handling fatal errors is to bring the S7-200 to a safe state from which the S7-200 can respond to interrogations about the existing error conditions When a fatal error is detected the S7-200 changes to STOP mode turns on the System Fault LED and the STOP LED overrides the output table and turns off the outputsThe S7-200 remains in this condition until the fatal error condition is corrected
Once you have made the changes to correct the fatal error condition use one of the following methods to restart the S7-200 1048600 Turn the power off and then on 1048600 Change the mode switch from RUN or TERM to STOP 1048600 Select the PLC gt Power-Up Reset menu command from STEP 7--MicroWIN
to restart the S7-200This forces the S7-200 to restart and clear any fatal errors
Restarting the S7-200 clears the fatal error condition and performs power-up diagnostic testing to verify that the fatal error has been corrected If another fatal error condition is found the S7-200 again sets the fault LED indicating that an error still exists Otherwise the S7-200 begins normal operation
Some error conditions can render the S7-200 incapable of communication In these cases you cannot view the error code from the S7-200 These types of errors indicate hardware failures that require the S7-200 to be repaired they cannot be fixed by changes to the program or clearing the memory of the S7-200
APPLICATIONS OF S7-200
Conveyer Systems
Elevators
Test Stations
Placement Systems
Woodworking Machinery
Packaging Equipment
Car Wash Automation
Remote Monitoring And Controlling For Water Wastewater
FEATURES OF LADDER DIAGRAMS
The LAD editor displays the program as a graphical representation similar to electrical wiring diagrams
Ladder programs allow the program to emulate the flow of electric current from a power source through a series of logical input conditions that in turn enable logical output conditions
A LAD program includes a left power rail that is energized Contacts that are closed allow energy to flow through them to the next element and contacts that are open block that energy flow
The logic is separated into networks The program is executed one network at a time from left to right and then top to bottom as dictated by the program Figure shows an example of a LAD program
The various instructions are represented by graphic symbols and include three basic forms
Contacts represent logic input conditions such as switches buttons or internal conditions
Coils usually represent logic output results such as lamps motor starters interposing relays or internal output conditions
Boxes represent additional instructions such as timers counters or math instructions Figure Sample LAD Program
Consider these main points when you select the LAD editor 1048600 Ladder logic is easy for beginning programmers to use 1048600 Graphical representation is easy to understand and is popular around the world 1048600 The LAD editor can be used with both the SIMATIC and IEC 1131--3 Instruction sets
1048600 You can always use the STL editor to display a program created with
the SIMATIC LAD editor
COMPONENTS LIST
Cardboard of 4050 sqcm
PLC S7-200
Sensors
LEDS
Buzzers
Motor
Contactors
Power supply
12v DC battery
Connecting wires
PPI Cable
SENSORS
A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact A proximity sensor often emits an electromagnetic or electrostatic field or a beam of electromagnetic radiation (infrared for instance) and looks for changes in the field or return signal The object being sensed is often referred to as the proximity sensors target Different
proximity sensor targets demand different sensors For example a capacitive or photoelectric sensor might be suitable for a plastic target an inductive proximity sensor requires a metal target
The maximum distance that this sensor can detect is defined nominal range Some sensors have adjustments of the nominal range or means to report a graduated detection distance
Proximity sensors can have a high reliability and long functional life because of the absence of mechanical parts and lack of physical contact between sensor and the sensed object
IEC 60947-5-2 defines the technical details of proximity sensors
A proximity sensor adjusted to a very short range is often used as a touch switch
Applications
Car bumpers that sense distance to nearby cars for parking
Ground proximity warning system for aviation safety Vibration Position measurements of rotating shafts in
machinery Sheet break sensing in paper machine Anti-aircraft artillery
LEDS
Example Circuit symbol
FunctionLEDs emit light when an electric current passes through them
Testing an LED
Never connect an LED directly to a battery or power supply
LEDs must have a resistor in series to limit the current to a safe value for quick testing purposes a 1k resistor is suitable for most LEDs if your supply voltage is 12V or less Remember to connect the LED the correct way round
Sizes Shapes and Viewing angles of LEDs
LEDs are available in a wide variety of sizes and shapes The standard LED has a round cross-section of 5mm diameter and this is probably the best type for general use but 3mm round LEDs are also popular
Round cross-section LEDs are frequently used and they are very easy to install on boxes by drilling a hole of the LED diameter adding a spot of glue will help to hold the LED if necessary LED clips are also available to secure LEDs in holes Other cross-section shapes include square rectangular and triangular
As well as a variety of colours sizes and shapes LEDs also vary in their viewing angle This tells you how much the beam of light spreads out Standard LEDs have a viewing angle of 60deg but others have a narrow beam of 30deg or less
Calculating an LED resistor value
An LED must have a resistor connected in series to limit the current through the LED otherwise it will burn out almost instantly
The resistor value R is given by
R = (VS - VL) I
VS = supply voltage VL = LED voltage (usually 2V but 4V for blue and white LEDs) I = LED current (eg 20mA) this must be less than the maximum permitted
If the calculated value is not available choose the nearest standard resistor value which is greater so that the current will be a little less than you chose In fact you may wish to choose a greater resistor value to reduce the current (to increase battery life for example) but this will make the LED less bright
Working out the LED resistor formula using Ohms law
Ohms law says that the resistance of the resistor R = VI where V = voltage across the resistor (= VS - VL in this case) I = the current through the resistor
So R = (VS - VL) I
BUZZERS
A buzzer or beeper (BUZZERS) is a signalling device usually electronic typically used in automobiles household appliances such as a microwave oven or game shows It most commonly consists of a number of switches or sensors connected to a control unit that determines if and which button was pushed or a preset time has lapsed and usually illuminates a light on the appropriate button or control panel and sounds a warning in the form of a continuous or intermittent buzzing
or beeping sound Initially this device was based on an electromechanical system which was identical to an electric bell without the metal gong (which makes the ringing noise) Often these units were anchored to a wall or ceiling and used the ceiling or wall as a sounding board Another implementation with some AC-connected devices was to implement a circuit to make the AC current into a noise loud enough to drive a loudspeaker and hook this circuit up to a cheap 8-ohm speaker Nowadays it is more popular to use a ceramic-based piezoelectric sounder which makes a high-pitched tone Usually these were hooked up to driver circuits which varied the pitch of the sound or pulsed the sound on and off
The word buzzer comes from the rasping noise that buzzers made when they were electromechanical devices operated from stepped-down AC line voltage at 50 or 60 cycles Other sounds commonly used to indicate that a button has been pressed are a ring or a beep
MOTORS
An electric motor is a device using electrical energy to produce mechanical energy nearly always by the interaction of magnetic fields and current-carrying conductors The reverse process that of using mechanical energy to produce electrical energy is accomplished by a generator or dynamo Traction motors used on vehicles often perform both tasks
Electric motors are found in myriad uses such as industrial fans blowers and pumps machine tools household appliances power tools and computer disk drives among
many other applications Electric motors may be operated by direct current from a battery in a portable device or motor vehicle or from alternating current from a central electrical distribution grid The smallest motors may be found in electric wristwatches Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses The very largest electric motors are used for propulsion of large ships and for such purposes as pipeline compressors with ratings in the thousands of kilowatts Electric motors may be classified by the source of electric power by their internal construction and by application
The physical principle of production of mechanical force by the interaction of an electric current and a magnetic field was known as early as 1821 Electric motors of increasing efficiency were constructed throughout the 19th century but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks
CONNECTORS
A DC connector is an electrical connector for
supplying direct current (DC) power DC connectors
are poorly standardized compared to domestic AC
power plugs and sockets DC plug is a common name
used for one common type of cylindrical two-conductor
plug available in a range of sizes and used to power
small pieces of electronic equipment It is also used to
describe some older multi-pin plugs
Several competing standards exist for DC plugs and in some cases incompatible plugs
will fit together to avoid damaging equipment these conditions must be true
Voltage must match
Polarity is correct
Current ratings are sufficient
Power supply filtering and stability is adequate
for the equipment being powered
Non-matching connectors are forced together
12V DC BATTERY
Features
Less than a 12 volt self discharge per 6 months 4 ea 12Vdc outputs 20 AmpHours Built-charger Digital Voltmeter
Description
This unit supplies a full 12Vdc at 20 AmpHours Designed for the officer that needs a power source that can be charged from 115Ac source or on the way to a incident from the car
The battery source has a very low self discharge rate which makes it perfect for law enforcement use The battery can set on the shelf for more than 6 months without recharging
Everyone knows when you grab a battery operated device the internal battery always requires several hours of charging before using The new voltage indicator reads out voltage to one hundredth of a volt for accurate operation The four outputs are 21mm plug Quick terminals and Cigarette lighter jack amp PT02 (Mil Spec) This model also allows powering
12Vdc sources while plugged in to 115Vac ldquoIts a UPSrdquo
SPECIFICATIONS OF COMPONENTS USED
PLC S7-200
INPUT POWER 230V AC 50 Hz
INPUTS 24 DC INPUTS
OUTPUTS 16 DC OUTPUTS
PROGRAM MEMORY 24
DATA MEMORY 10KB
EXPANSION MODULES 7
COMMUNICATION PORTS 2 RS 485
DIGITAL IO IMAGE SIZE 256(128 in 128 out)
EXECUTION SPEED 022microsecondsinstruction
SENSORS
SENSING RANGE 3mm
HOUSING MATERIAL Brass Nickel Plated
OPERATING VOLTAGE 10-30V
OPERATING CURRENT lt200mA
CONNECTION TYPE Cable
LEDS
DIAMETER 5mm
MAXIMUM VOLTAGE 1V
MAXIMUM CURRENT 10mA
INTENSITY
BUZZERS
OPERATING VOLTAGE30Vp-p
RATED FREQUENCY2000Hz 500Hz
OPERATING TEMP RANGE -20 to 60 degree
SOUND OUTPUT70 dB min10 cm
MOTOR
TOTAL LENGTH 46mm MOTOR DIAMETER 36mm MOTOR LENGTH 25mm DC SUPPLY 4 to 12V RPM 100 BRUSH TYPE Precious metal GEAR HEAD DIAMETER 37mm GEAR HEAD LENGTH 21mm OUTPUT SHAFT Centered SHAFT DIAMETER 4mm and 6mm
SHAFT LENGTH 22mm
- Block diagram of plc
- Applications
-
- Function
- Testing an LED
- Sizes Shapes and Viewing angles of LEDs
- Calculating an LED resistor value
-
- Working out the LED resistor formula using Ohms law
-
In this fast developing science revolutionary era automation of an industry has become a necessity A PLC (Programmable Logic Controller) is a programmable system used for automation The Programmable Logic Controller may be defined as ldquoA PLC is a microprocessor based specialized computer that carries out the control functions of many types and levels of complexityrdquo
A PLC has many input terminals through which it interprets high and low logical states from sensors and switches It also has many output terminals through which it outputs high and low signals to power lights solenoids contactors small motors and other devices lending themselves to onoff control
We have designed a kit for automating a car parking guidance system For this a PLC (Siemens S7-200) has been used The PLC has been pre-programmed and is the brain of the system It reads the inputs from the various sensors and makes logical decisions These logical decisions are given to the PLC by using a suitable programming language Accordingly the necessary operation is carried out Our project illustrates only a simple application of the PLC while the PLC is a powerful tool the applications of which are innumerable and complex
PLATFORM S7-200 PLC
PROGRAMMING LANGUAGE LADDER DIAGRAMS
SOFTWARE S7 MICROWIN
KEYWORDS SENSORS BUZZERS LEDS AUTOMATION
LADDER LOGIC MEMORY
1 INTRODUCTION
A programmable logic controller (PLC) or programmable controller is a digital computer used for automation of electromechanical processes such as control of machinery on factory assembly lines amusement rides or lighting fixtures PLCs are
used in many industries and machines such as packaging and semiconductor machines Unlike general-purpose computers the PLC is designed for multiple inputs and output arrangements extended temperature ranges immunity to electrical noise and resistance to vibration and impact Programs to control machine operation are typically stored in battery-backed or non-volatile memory A PLC is an example of a real time system since output results must be produced in response to input conditions within a bounded time otherwise unintended operation will result
A PLC has many input terminals through which it interprets high and low logical states from sensors and switches It also has many output terminals through which it outputs high and low signals to power lights solenoids contactors small motors and other devices lending themselves to onoff control In an effort to make PLCs easy to program their programming language was designed to resemble ladder logic diagrams Thus an industrial electrician or electrical engineer accustomed to reading ladder logic schematics would feel comfortable programming a PLC to perform the same control functions
PLCs are industrial computers and as such their input and output signals are typically 120 volts AC just like the electromechanical control relays they were designed to replace Although some PLCs have the ability to input and output low-level DC voltage signals of the magnitude used in logic gate circuits this is the exception and not the rule
The actual logic of the control system is established inside the PLC by means of a computer program This program dictates which output gets energized under which input conditions Although the program itself appears to be a ladder logic diagram with switch and relay symbols there are no actual switch contacts or relay coils operating inside the PLC to create the logical relationships between input and output These are imaginary contacts and coils if you will The program is entered and viewed via a personal computer connected to the PLCs programming port
The true power and versatility of a PLC is revealed when we want to alter the behavior of a control system Since the PLC is a programmable device we can alter its behavior by changing the commands we give it without having to reconfigure the electrical components connected to it
One of the advantages of implementing logical control in software rather than in hardware is that input signals can be re-used as many times in the program as is necessary Another advantage of PLCs that simply cannot be duplicated by electromechanical relays is remote monitoring and control via digital computer networks Because a PLC is nothing more than a special-purpose digital computer it has the ability to communicate with other computers rather easily
2 HISTORY
21 ORIGIN
The PLC was invented in response to the needs of the American automotive manufacturing industry Programmable controllers were initially adopted by the automotive industry where software revision replaced the re-wiring of hard-wired control panels when production models changed
Before the PLC control sequencing and safety interlock logic for manufacturing automobiles was accomplished using hundreds or thousands of relays cam timers and drum sequencers and dedicated closed-loop controllers The process for updating such facilities for the yearly model change-over was very time consuming and expensive as the relay systems needed to be rewired by skilled electricians
In 1968 GM Hydramatic (the automatic transmission division of General Motors) issued a request for proposal for an electronic replacement for hard-wired relay systems
The winning proposal came from Bedford Associates of Bedford Massachusetts The first PLC designated the 084 because it was Bedford Associates eighty-fourth project was the result Bedford Associates started a new company dedicated to developing manufacturing selling and servicing this new product MODICON which stood for MOdular DIgital CONtroller One of the people who worked on that project was Dick Morley who is considered to be the father of the PLC The MODICON brand was sold in 1977 to Gould Electronics and later acquired by German Company AEG and then by French Schneider Electric the current owner
One of the very first 084 models built is now on display at Modicons headquarters in North Andover Massachusetts It was presented to Modicon by GM when the unit was retired after nearly twenty years of uninterrupted service Modicon used the 84 moniker at the end of its product range until the 984 made its appearance
The automotive industry is still one of the largest users of PLCs
22 DEVELOPMENT
Early PLCs were designed to replace relay logic systems These PLCs were programmed in ladder logic which strongly resembles a schematic diagram of relay logic Modern PLCs can be programmed in a variety of ways from ladder logic to more traditional programming languages such as BASIC and C Another method is State Logic a very high-level programming language designed to program PLCs based on state transition diagrams
Many of the earliest PLCs expressed all decision making logic in simple ladder logic which appeared similar to electrical schematic diagrams This program notation was chosen to reduce training demands for the existing technicians Other early PLCs used a form of instruction list programming based on a stack-based logic solver
23 PROGRAMMING
Early PLCs up to the mid-1980s were programmed using proprietary programming panels or special-purpose programming terminals which often had dedicated function keys representing the various logical elements of PLC programs Programs were stored on cassette tape cartridges Facilities for printing and documentation were very minimal due to lack of memory capacity The very oldest PLCs used non-volatile magnetic core memory
24 FUNCTIONALITY
The functionality of the PLC has evolved over the years to include sequential relay control motion control process control distributed control systems and networking The data handling storage processing power and communication capabilities of some modern PLCs are approximately equivalent to desktop computers PLC-like programming combined with remote IO hardware allow a general-purpose desktop computer to overlap some PLCs in certain applications
PLC ARCHITECTURE
CPU
Power Supply
Memory
Input Blocks
Output Blocks
Communications
Expansion Connections
BLOCK DIAGRAM OF PLC
SENSORS
PLC COMPARED WITH OTHER CONTROL SYSTEMS
PLCs are well-adapted to a range of automation tasks These are typically industrial processes in manufacturing where the cost of developing and maintaining the automation system is high relative to the total cost of the automation and where changes to the system would be expected during its operational life PLCs contain input and output devices compatible with industrial pilot devices and controls little electrical design is required and the design problem centers on expressing the desired sequence of operations in ladder logic (or function chart) notation PLC applications are typically highly customized systems so the cost of a packaged PLC is low compared to the cost of a specific custom-built controller design On the other hand in the case of mass-produced goods customized control systems are economic due to the lower cost of the components which can be optimally chosen instead of a generic solution and where the non-recurring engineering charges are spread over thousands or millions of units
For high volume or very simple fixed automation tasks different techniques are used A microcontroller-based design would be appropriate where hundreds or thousands of units will be produced and so the development cost (design of power supplies and inputoutput hardware) can be spread over many sales and where the end-user would not need to alter the control Automotive applications are an example millions of units are built each year and very few end-users alter the programming of these controllers
Power supply
Input
Module
Memory
Processor
Output
Module
However some specialty vehicles such as transit busses economically use PLCs instead of custom-designed controls because the volumes are low and the development cost would be uneconomic
Very complex process control such as used in the chemical industry may require algorithms and performance beyond the capability of even high-performance PLCs Very high-speed or precision controls may also require customized solutions for example aircraft flight controls
Programmable controllers are widely used in motion control positioning control and torque control Some manufacturers produce motion control units to be integrated with PLC so that G-code (involving a CNC machine) can be used to instruct machine movements
PLCs may include logic for single-variable feedback analog control loop a proportional integral derivative or PID controller A PID loop could be used to control the temperature of a manufacturing process for example Historically PLCs were usually configured with only a few analog control loops where processes required hundreds or thousands of loops a distributed control system (DCS) would instead be used As PLCs have become more powerful the boundary between DCS and PLC applications has become less distinct
PLCs have similar functionality as Remote Terminal Units An RTU however usually does not support control algorithms or control loops As hardware rapidly becomes more powerful and cheaper RTUs PLCs and DCSs are increasingly beginning to overlap in responsibilities The industry has standardized on the IEC 61131-3 functional block language for creating programs to run on RTUs and PLCs although nearly all vendors also offer proprietary alternatives and associated development environments
DISADVANTAGES OF lsquoHARD WIRED LOGIC CONTROLrsquo
Bulky panels
Complex wiring
Longer project time
Difficult maintenance and troubleshooting
ADVANTAGES OF lsquoPLCSrsquo
Reduced space
Ease of maintenance
Economical
Greater life amp reliability
Tremendous flexibility
Shorter project time
Easier storage archiving and documentation
WHAT CONSTITUTES A PLC
The PLC is programmed interface between the Input field elements amp output field
elements
PLC consist of
Hardware
Input Module
CPU (Central Process Unit)
Program memory
Output module
Power Supply
Software
Application Software (Logic)
Basic Software
Communication Accessories
Communication Adapter
INPUT-OUTPUT
Input and output (IO) modules connect the PLC to
sensors and actuators
Provide isolation for the low-voltage low-current
signals
Wide range of IO modules available including
Digital (logical) IO modules and Analogue (continuous) IO modules
Analogue input cards convert continuous signals via an AD converter into discrete
values for the PLC
Analogue output cards convert digital values in then PLC to continuous signals via a
DA converter
Resolution can be important in choosing an applicable card
Module receptacle for battery EEPROM
CPU statu
s LEDrsquo
sCommunicatio
ns interfa
ce
Status LEDrsquos of
the inputs
and outputs
Fixing holes for wall
mounting
Locking clip for DIN rail mounting
Analog potentiometer
Removable
connection
terminals(on 224 226)
Example for a temperature input of 0 to 100 degrees C
For 8 bit resolution the value in the PLC is 0 to 255
For 12 bit resolution the value in the PLC is 0 to 4095
For 16 bit resolution the value in the PLC is 0 to 32768
SPECIAL MODULES
RF ID
Modem modules
Load Cell
Stepper Modules
Temperature Sensor
High Speed Counters
Position Control Cards
Field Bus Cards
o Device Net Profibus Ethernet etc
ELEMENTS OF INPUTS
Digital Inputs
push button
limit switches
Sensors
o Proximity Sensors
o Photo Sensors
Micro Switches
Toggle Switches
Analog Inputs
Pressure Transmitters
Flow Transmitter
Level Transmitter
Thermo Couples
Load Cell
ELEMENTS OF OUTPUTS
Digital Outputs
Relays
Contactors
Indication Lamps
Valves
Analog Outputs
Flow Control Valves
Pressure Control Valves
Drive Inputs
BASIC ELEMENTS OF A PROGRAM
A program block is composed of executable code and comments The executable codes consist of a main program and any subroutines or interrupt routines The code is compiled and downloaded to the S7-200 the program comments are not You can use the organizational elements (main program subroutines and interrupt routines) to structure your control program
Main ProgramThe main body of the program contains the instructions that control your application The S7-200 executes these instructions sequentially once per scan cycle The main program is also referred to as OB1
SubroutinesThese optional elements of your program are executed only when called by the main program by an interrupt routine or by another subroutine Subroutines are useful in cases where you want to execute a function repeatedly Rather than rewriting the logic for each place in the main program where you want the function to occur you can write the logic once in a subroutine and call the subroutine as many times as needed during the main program Subroutines provide several benefits
1048600 Using subroutines reduces the overall size of your program 1048600 Using subroutines decreases your scan time because you have moved the code out of the main program The S7-200 evaluates the code in the main program every scan cycle whether the code is executed or not but the S7-200 evaluates the code in the subroutine only when you call the subroutine and does not evaluate the code during the scans in which the subroutine is not called 1048600 Using subroutines creates code that is portable You can isolate the code for a function in a subroutine and then copy that subroutine into other programs with Interrupt RoutinesThese optional elements of your program react to specific interrupt events You design an interrupt routine to handle a pre-defined interrupt event Whenever the specified event occurs the S7-200 executes the interrupt routineThe interrupt routines are not called by your main program You associate an interrupt routine with an interrupt event and the S7-200 executes the instructions in the interrupt routine only on each occurrence of the interrupt event Other Elements of the ProgramOther blocks contain information for the S7-200 You can choose to download these blocks when you download your programSystem BlockThe system block allows you to configure different hardware options for the S7-200Data BlockThe data block stores the values for different variables (V memory) used by your program You can use the data block to enter initial values for the data
PROGRAMMING LANGUAGES IN PLC
IL (Instruction List) ndash mnemonic programming
LD (Ladder Diagram) ndash Relay logic
ST (Structured Text) ndash A C like programming language
FDB (Functional Block Diagram) ndash Graphical dataflow programming language
SFC (Sequential Flow Chart) ndash Graphical method for structured programs
Basic PLC Memory
Memory on a PLC is separated into 3 main areas
LOAD Memory
Can be RAM (dynamic) or EEPROM (retentive)
Used to store user programs
WORK Memory
Memory is RAM
When PLC starts Program is copied from LOAD memory to
WORK memory The program is then executed from Work
memory
SYSTEM Memory
Memory is RAM
Is used by micro-controller to implement counters timers interrupt
stacks etc
Contains a bit for each D I0
Contains ldquoMarker Memoryrdquo Marker memory is a free area of RAM
that can be used by the programmer
Contains ldquoProcess Input and Output Imagesrdquo Periodically the PLC
will store the states of the inputs to the Process Input Image and
Process Output Image to the output
SELECTION OF A PLC
Selection of PLC Based on
No of Inputs amp Outputs
Input Voltage
Memory
Scan Time
Special IO modules
Expansion Capabilities
Stand alone or Networked
Communication Capabilities
HOW PLC WORKS
Step 1-CHECKING INPUT STATUS
o PLC Scans each input
o Records the data in work memory
Step 2-EXECUTE PROGRAM
o PLC goes through the program logic step by step
o PLC executes the program depending on input status
o Write the output image in work memory
Step 3-UPDATE OUTPUT STATUS
o Changes the statues of the output onoff
o Again starts the cycle from step one
FEATURES OF S7-200
Allows Your Program to Immediately Read or Write the IO
Allows Your Program to Interrupt the Scan Cycle
Allows You to Allocate Processing Time for Communications
Tasks
Allows You to Set the States of Digital Outputs for Stop
CHECK
INPUT STATUS
EXECUTE
PROGRAM
UPDATE
OUTPUT STATUS
Mode
Allows You to Define Memory to Be Retained on Loss of Power
Allows You to Filter the Digital Inputs
Allows You to Filter the Analog Inputs
Allows You to Catch Pulses of Short Duration
Provides Password Protection
Provides Analog Adjustment Potentiometers
Provides High-speed IO
TECHNICAL FEATURES OF S7-200
Several models of CPUrsquos
o CPU 221 6in4out 2Kw program
o CPU 222 8in6out 2Kw program
o CPU 224 14in10out 4Kw program
o CPU 226 24in16out 4Kw program
Up to 256 digital input-outputs
Up to 32 analog channels
256 timers 256 counters
Built-in EEPROM memory
Real-time clockcalendar
Built-in communications
Password protection
Memory module
Removable input-output connectors
Wide range of expansion modules
o 8 pt input and output
o 4488 amp1616 inout combination
o 4 channel analog in 2 channel analog out
o 4 ch1ch analog inout combination
o 2 channel RTD in
o 4 channel thermocouple in
o PROFIBUS-DP Slave
o AS Interface master
SELECTING THE OPERATING MODE FOR THE S7- 200 CPU
The S7-200 has two modes of operation STOP mode and RUN mode The status LED on the front of the CPU indicates the current mode of operation In STOP mode the S7-200 is not executing the program and you can download a program or the CPU configuration In RUN mode the S7-200 is running the program
1048600 The S7-200 provides a mode switch for changing the mode of operation You can use the mode switch (located under the front access door of the S7-200) to manually select the operating mode setting the mode switch to STOP mode stops the execution of the program setting the mode switch to RUN mode starts the execution of the program and setting the mode switch to TERM (terminal) mode does not change the operating mode
If a power cycle occurs when the mode switch is set to either STOP or TERM the
S7-200 goes automatically to STOP mode when power is restored If a power cycle occurs when the mode switch is set to RUN the S7-200 goes to RUN mode when power is restored
1048600 STEP 7--MicroWIN allows you to change the operating mode of the online S7-200 To enable the software to change the operating mode you must manually set the mode switch on the S7-200 to either TERM or RUN You can use the PLC gt STOP or PLC gt RUN menu commands or the associated buttons on the toolbar to change the operating mode
1048600 You can insert the STOP instruction in your program to change the S7-200 to STOP mode This allows you to halt the execution of your program based on the program logic
ERRORS IN S7-200
Non-Fatal Errors
Non-fatal errors are those indicating problems with the construction of the user program with the execution of an instruction in the user program and with expansion IO modules You can use STEP 7--MicroWIN to view the error codes that were generated by the non-fatal error There are three basic categories of non-fatal errors
Program-compile errorsThe S7-200 compiles the program as it downloads If the S7-200 detects that the program violates a compilation rule the download is aborted and an error code is generated (A program that was already downloaded to the S7-200 would still exist in the EEPROM and would not be lost) After you correct your program you can download it again
IO errorsAt startup the S7-200 reads the IO configuration from each module During normal operation the S7-200 periodically checks the status of each module and compares it against the configuration obtained during startup If the S7-200 detects a difference the S7-200 sets the configuration error bit in the module error register The S7-200 does not read input data from or write output data to that module until the module configuration again matches the one obtained at startupThe module status information is stored in special memory (SM) bits Your program can monitor and evaluate these bits Refer to Appendix D for more information about the SM bits used for reporting IO errors SM50 is the global IO error bit and remains set while an error condition exists on an expansion module
Program execution errorsYour program can create error conditions while being executed These errors can result from improper use of an instruction or from the processing of invalid data by an instruction For example an indirect-address pointer that was valid when the program compiled could be modified during the execution of the program to point to an out-of-range address This is an example of a run-time programming problem SM43 is setupon the occurrence of a run-time programming problem and remains set while the S7-200 is in RUN mode Program execution error information is stored in special memory (SM) bits Your program can monitor and evaluate these bits The S7-200 does not change to STOP mode when it detects a non-fatal error It only logs the event in SM memory and continues with the execution of your program However you can design your program to force the S7-200 to STOP mode when a non-fatal error is detected
Fatal Errors
Fatal errors cause the S7-200 to stop the execution of your program Depending upon the severity of the fatal error it can render the S7-200 incapable of performing any or all functions The objective for handling fatal errors is to bring the S7-200 to a safe state from which the S7-200 can respond to interrogations about the existing error conditions When a fatal error is detected the S7-200 changes to STOP mode turns on the System Fault LED and the STOP LED overrides the output table and turns off the outputsThe S7-200 remains in this condition until the fatal error condition is corrected
Once you have made the changes to correct the fatal error condition use one of the following methods to restart the S7-200 1048600 Turn the power off and then on 1048600 Change the mode switch from RUN or TERM to STOP 1048600 Select the PLC gt Power-Up Reset menu command from STEP 7--MicroWIN
to restart the S7-200This forces the S7-200 to restart and clear any fatal errors
Restarting the S7-200 clears the fatal error condition and performs power-up diagnostic testing to verify that the fatal error has been corrected If another fatal error condition is found the S7-200 again sets the fault LED indicating that an error still exists Otherwise the S7-200 begins normal operation
Some error conditions can render the S7-200 incapable of communication In these cases you cannot view the error code from the S7-200 These types of errors indicate hardware failures that require the S7-200 to be repaired they cannot be fixed by changes to the program or clearing the memory of the S7-200
APPLICATIONS OF S7-200
Conveyer Systems
Elevators
Test Stations
Placement Systems
Woodworking Machinery
Packaging Equipment
Car Wash Automation
Remote Monitoring And Controlling For Water Wastewater
FEATURES OF LADDER DIAGRAMS
The LAD editor displays the program as a graphical representation similar to electrical wiring diagrams
Ladder programs allow the program to emulate the flow of electric current from a power source through a series of logical input conditions that in turn enable logical output conditions
A LAD program includes a left power rail that is energized Contacts that are closed allow energy to flow through them to the next element and contacts that are open block that energy flow
The logic is separated into networks The program is executed one network at a time from left to right and then top to bottom as dictated by the program Figure shows an example of a LAD program
The various instructions are represented by graphic symbols and include three basic forms
Contacts represent logic input conditions such as switches buttons or internal conditions
Coils usually represent logic output results such as lamps motor starters interposing relays or internal output conditions
Boxes represent additional instructions such as timers counters or math instructions Figure Sample LAD Program
Consider these main points when you select the LAD editor 1048600 Ladder logic is easy for beginning programmers to use 1048600 Graphical representation is easy to understand and is popular around the world 1048600 The LAD editor can be used with both the SIMATIC and IEC 1131--3 Instruction sets
1048600 You can always use the STL editor to display a program created with
the SIMATIC LAD editor
COMPONENTS LIST
Cardboard of 4050 sqcm
PLC S7-200
Sensors
LEDS
Buzzers
Motor
Contactors
Power supply
12v DC battery
Connecting wires
PPI Cable
SENSORS
A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact A proximity sensor often emits an electromagnetic or electrostatic field or a beam of electromagnetic radiation (infrared for instance) and looks for changes in the field or return signal The object being sensed is often referred to as the proximity sensors target Different
proximity sensor targets demand different sensors For example a capacitive or photoelectric sensor might be suitable for a plastic target an inductive proximity sensor requires a metal target
The maximum distance that this sensor can detect is defined nominal range Some sensors have adjustments of the nominal range or means to report a graduated detection distance
Proximity sensors can have a high reliability and long functional life because of the absence of mechanical parts and lack of physical contact between sensor and the sensed object
IEC 60947-5-2 defines the technical details of proximity sensors
A proximity sensor adjusted to a very short range is often used as a touch switch
Applications
Car bumpers that sense distance to nearby cars for parking
Ground proximity warning system for aviation safety Vibration Position measurements of rotating shafts in
machinery Sheet break sensing in paper machine Anti-aircraft artillery
LEDS
Example Circuit symbol
FunctionLEDs emit light when an electric current passes through them
Testing an LED
Never connect an LED directly to a battery or power supply
LEDs must have a resistor in series to limit the current to a safe value for quick testing purposes a 1k resistor is suitable for most LEDs if your supply voltage is 12V or less Remember to connect the LED the correct way round
Sizes Shapes and Viewing angles of LEDs
LEDs are available in a wide variety of sizes and shapes The standard LED has a round cross-section of 5mm diameter and this is probably the best type for general use but 3mm round LEDs are also popular
Round cross-section LEDs are frequently used and they are very easy to install on boxes by drilling a hole of the LED diameter adding a spot of glue will help to hold the LED if necessary LED clips are also available to secure LEDs in holes Other cross-section shapes include square rectangular and triangular
As well as a variety of colours sizes and shapes LEDs also vary in their viewing angle This tells you how much the beam of light spreads out Standard LEDs have a viewing angle of 60deg but others have a narrow beam of 30deg or less
Calculating an LED resistor value
An LED must have a resistor connected in series to limit the current through the LED otherwise it will burn out almost instantly
The resistor value R is given by
R = (VS - VL) I
VS = supply voltage VL = LED voltage (usually 2V but 4V for blue and white LEDs) I = LED current (eg 20mA) this must be less than the maximum permitted
If the calculated value is not available choose the nearest standard resistor value which is greater so that the current will be a little less than you chose In fact you may wish to choose a greater resistor value to reduce the current (to increase battery life for example) but this will make the LED less bright
Working out the LED resistor formula using Ohms law
Ohms law says that the resistance of the resistor R = VI where V = voltage across the resistor (= VS - VL in this case) I = the current through the resistor
So R = (VS - VL) I
BUZZERS
A buzzer or beeper (BUZZERS) is a signalling device usually electronic typically used in automobiles household appliances such as a microwave oven or game shows It most commonly consists of a number of switches or sensors connected to a control unit that determines if and which button was pushed or a preset time has lapsed and usually illuminates a light on the appropriate button or control panel and sounds a warning in the form of a continuous or intermittent buzzing
or beeping sound Initially this device was based on an electromechanical system which was identical to an electric bell without the metal gong (which makes the ringing noise) Often these units were anchored to a wall or ceiling and used the ceiling or wall as a sounding board Another implementation with some AC-connected devices was to implement a circuit to make the AC current into a noise loud enough to drive a loudspeaker and hook this circuit up to a cheap 8-ohm speaker Nowadays it is more popular to use a ceramic-based piezoelectric sounder which makes a high-pitched tone Usually these were hooked up to driver circuits which varied the pitch of the sound or pulsed the sound on and off
The word buzzer comes from the rasping noise that buzzers made when they were electromechanical devices operated from stepped-down AC line voltage at 50 or 60 cycles Other sounds commonly used to indicate that a button has been pressed are a ring or a beep
MOTORS
An electric motor is a device using electrical energy to produce mechanical energy nearly always by the interaction of magnetic fields and current-carrying conductors The reverse process that of using mechanical energy to produce electrical energy is accomplished by a generator or dynamo Traction motors used on vehicles often perform both tasks
Electric motors are found in myriad uses such as industrial fans blowers and pumps machine tools household appliances power tools and computer disk drives among
many other applications Electric motors may be operated by direct current from a battery in a portable device or motor vehicle or from alternating current from a central electrical distribution grid The smallest motors may be found in electric wristwatches Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses The very largest electric motors are used for propulsion of large ships and for such purposes as pipeline compressors with ratings in the thousands of kilowatts Electric motors may be classified by the source of electric power by their internal construction and by application
The physical principle of production of mechanical force by the interaction of an electric current and a magnetic field was known as early as 1821 Electric motors of increasing efficiency were constructed throughout the 19th century but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks
CONNECTORS
A DC connector is an electrical connector for
supplying direct current (DC) power DC connectors
are poorly standardized compared to domestic AC
power plugs and sockets DC plug is a common name
used for one common type of cylindrical two-conductor
plug available in a range of sizes and used to power
small pieces of electronic equipment It is also used to
describe some older multi-pin plugs
Several competing standards exist for DC plugs and in some cases incompatible plugs
will fit together to avoid damaging equipment these conditions must be true
Voltage must match
Polarity is correct
Current ratings are sufficient
Power supply filtering and stability is adequate
for the equipment being powered
Non-matching connectors are forced together
12V DC BATTERY
Features
Less than a 12 volt self discharge per 6 months 4 ea 12Vdc outputs 20 AmpHours Built-charger Digital Voltmeter
Description
This unit supplies a full 12Vdc at 20 AmpHours Designed for the officer that needs a power source that can be charged from 115Ac source or on the way to a incident from the car
The battery source has a very low self discharge rate which makes it perfect for law enforcement use The battery can set on the shelf for more than 6 months without recharging
Everyone knows when you grab a battery operated device the internal battery always requires several hours of charging before using The new voltage indicator reads out voltage to one hundredth of a volt for accurate operation The four outputs are 21mm plug Quick terminals and Cigarette lighter jack amp PT02 (Mil Spec) This model also allows powering
12Vdc sources while plugged in to 115Vac ldquoIts a UPSrdquo
SPECIFICATIONS OF COMPONENTS USED
PLC S7-200
INPUT POWER 230V AC 50 Hz
INPUTS 24 DC INPUTS
OUTPUTS 16 DC OUTPUTS
PROGRAM MEMORY 24
DATA MEMORY 10KB
EXPANSION MODULES 7
COMMUNICATION PORTS 2 RS 485
DIGITAL IO IMAGE SIZE 256(128 in 128 out)
EXECUTION SPEED 022microsecondsinstruction
SENSORS
SENSING RANGE 3mm
HOUSING MATERIAL Brass Nickel Plated
OPERATING VOLTAGE 10-30V
OPERATING CURRENT lt200mA
CONNECTION TYPE Cable
LEDS
DIAMETER 5mm
MAXIMUM VOLTAGE 1V
MAXIMUM CURRENT 10mA
INTENSITY
BUZZERS
OPERATING VOLTAGE30Vp-p
RATED FREQUENCY2000Hz 500Hz
OPERATING TEMP RANGE -20 to 60 degree
SOUND OUTPUT70 dB min10 cm
MOTOR
TOTAL LENGTH 46mm MOTOR DIAMETER 36mm MOTOR LENGTH 25mm DC SUPPLY 4 to 12V RPM 100 BRUSH TYPE Precious metal GEAR HEAD DIAMETER 37mm GEAR HEAD LENGTH 21mm OUTPUT SHAFT Centered SHAFT DIAMETER 4mm and 6mm
SHAFT LENGTH 22mm
- Block diagram of plc
- Applications
-
- Function
- Testing an LED
- Sizes Shapes and Viewing angles of LEDs
- Calculating an LED resistor value
-
- Working out the LED resistor formula using Ohms law
-
used in many industries and machines such as packaging and semiconductor machines Unlike general-purpose computers the PLC is designed for multiple inputs and output arrangements extended temperature ranges immunity to electrical noise and resistance to vibration and impact Programs to control machine operation are typically stored in battery-backed or non-volatile memory A PLC is an example of a real time system since output results must be produced in response to input conditions within a bounded time otherwise unintended operation will result
A PLC has many input terminals through which it interprets high and low logical states from sensors and switches It also has many output terminals through which it outputs high and low signals to power lights solenoids contactors small motors and other devices lending themselves to onoff control In an effort to make PLCs easy to program their programming language was designed to resemble ladder logic diagrams Thus an industrial electrician or electrical engineer accustomed to reading ladder logic schematics would feel comfortable programming a PLC to perform the same control functions
PLCs are industrial computers and as such their input and output signals are typically 120 volts AC just like the electromechanical control relays they were designed to replace Although some PLCs have the ability to input and output low-level DC voltage signals of the magnitude used in logic gate circuits this is the exception and not the rule
The actual logic of the control system is established inside the PLC by means of a computer program This program dictates which output gets energized under which input conditions Although the program itself appears to be a ladder logic diagram with switch and relay symbols there are no actual switch contacts or relay coils operating inside the PLC to create the logical relationships between input and output These are imaginary contacts and coils if you will The program is entered and viewed via a personal computer connected to the PLCs programming port
The true power and versatility of a PLC is revealed when we want to alter the behavior of a control system Since the PLC is a programmable device we can alter its behavior by changing the commands we give it without having to reconfigure the electrical components connected to it
One of the advantages of implementing logical control in software rather than in hardware is that input signals can be re-used as many times in the program as is necessary Another advantage of PLCs that simply cannot be duplicated by electromechanical relays is remote monitoring and control via digital computer networks Because a PLC is nothing more than a special-purpose digital computer it has the ability to communicate with other computers rather easily
2 HISTORY
21 ORIGIN
The PLC was invented in response to the needs of the American automotive manufacturing industry Programmable controllers were initially adopted by the automotive industry where software revision replaced the re-wiring of hard-wired control panels when production models changed
Before the PLC control sequencing and safety interlock logic for manufacturing automobiles was accomplished using hundreds or thousands of relays cam timers and drum sequencers and dedicated closed-loop controllers The process for updating such facilities for the yearly model change-over was very time consuming and expensive as the relay systems needed to be rewired by skilled electricians
In 1968 GM Hydramatic (the automatic transmission division of General Motors) issued a request for proposal for an electronic replacement for hard-wired relay systems
The winning proposal came from Bedford Associates of Bedford Massachusetts The first PLC designated the 084 because it was Bedford Associates eighty-fourth project was the result Bedford Associates started a new company dedicated to developing manufacturing selling and servicing this new product MODICON which stood for MOdular DIgital CONtroller One of the people who worked on that project was Dick Morley who is considered to be the father of the PLC The MODICON brand was sold in 1977 to Gould Electronics and later acquired by German Company AEG and then by French Schneider Electric the current owner
One of the very first 084 models built is now on display at Modicons headquarters in North Andover Massachusetts It was presented to Modicon by GM when the unit was retired after nearly twenty years of uninterrupted service Modicon used the 84 moniker at the end of its product range until the 984 made its appearance
The automotive industry is still one of the largest users of PLCs
22 DEVELOPMENT
Early PLCs were designed to replace relay logic systems These PLCs were programmed in ladder logic which strongly resembles a schematic diagram of relay logic Modern PLCs can be programmed in a variety of ways from ladder logic to more traditional programming languages such as BASIC and C Another method is State Logic a very high-level programming language designed to program PLCs based on state transition diagrams
Many of the earliest PLCs expressed all decision making logic in simple ladder logic which appeared similar to electrical schematic diagrams This program notation was chosen to reduce training demands for the existing technicians Other early PLCs used a form of instruction list programming based on a stack-based logic solver
23 PROGRAMMING
Early PLCs up to the mid-1980s were programmed using proprietary programming panels or special-purpose programming terminals which often had dedicated function keys representing the various logical elements of PLC programs Programs were stored on cassette tape cartridges Facilities for printing and documentation were very minimal due to lack of memory capacity The very oldest PLCs used non-volatile magnetic core memory
24 FUNCTIONALITY
The functionality of the PLC has evolved over the years to include sequential relay control motion control process control distributed control systems and networking The data handling storage processing power and communication capabilities of some modern PLCs are approximately equivalent to desktop computers PLC-like programming combined with remote IO hardware allow a general-purpose desktop computer to overlap some PLCs in certain applications
PLC ARCHITECTURE
CPU
Power Supply
Memory
Input Blocks
Output Blocks
Communications
Expansion Connections
BLOCK DIAGRAM OF PLC
SENSORS
PLC COMPARED WITH OTHER CONTROL SYSTEMS
PLCs are well-adapted to a range of automation tasks These are typically industrial processes in manufacturing where the cost of developing and maintaining the automation system is high relative to the total cost of the automation and where changes to the system would be expected during its operational life PLCs contain input and output devices compatible with industrial pilot devices and controls little electrical design is required and the design problem centers on expressing the desired sequence of operations in ladder logic (or function chart) notation PLC applications are typically highly customized systems so the cost of a packaged PLC is low compared to the cost of a specific custom-built controller design On the other hand in the case of mass-produced goods customized control systems are economic due to the lower cost of the components which can be optimally chosen instead of a generic solution and where the non-recurring engineering charges are spread over thousands or millions of units
For high volume or very simple fixed automation tasks different techniques are used A microcontroller-based design would be appropriate where hundreds or thousands of units will be produced and so the development cost (design of power supplies and inputoutput hardware) can be spread over many sales and where the end-user would not need to alter the control Automotive applications are an example millions of units are built each year and very few end-users alter the programming of these controllers
Power supply
Input
Module
Memory
Processor
Output
Module
However some specialty vehicles such as transit busses economically use PLCs instead of custom-designed controls because the volumes are low and the development cost would be uneconomic
Very complex process control such as used in the chemical industry may require algorithms and performance beyond the capability of even high-performance PLCs Very high-speed or precision controls may also require customized solutions for example aircraft flight controls
Programmable controllers are widely used in motion control positioning control and torque control Some manufacturers produce motion control units to be integrated with PLC so that G-code (involving a CNC machine) can be used to instruct machine movements
PLCs may include logic for single-variable feedback analog control loop a proportional integral derivative or PID controller A PID loop could be used to control the temperature of a manufacturing process for example Historically PLCs were usually configured with only a few analog control loops where processes required hundreds or thousands of loops a distributed control system (DCS) would instead be used As PLCs have become more powerful the boundary between DCS and PLC applications has become less distinct
PLCs have similar functionality as Remote Terminal Units An RTU however usually does not support control algorithms or control loops As hardware rapidly becomes more powerful and cheaper RTUs PLCs and DCSs are increasingly beginning to overlap in responsibilities The industry has standardized on the IEC 61131-3 functional block language for creating programs to run on RTUs and PLCs although nearly all vendors also offer proprietary alternatives and associated development environments
DISADVANTAGES OF lsquoHARD WIRED LOGIC CONTROLrsquo
Bulky panels
Complex wiring
Longer project time
Difficult maintenance and troubleshooting
ADVANTAGES OF lsquoPLCSrsquo
Reduced space
Ease of maintenance
Economical
Greater life amp reliability
Tremendous flexibility
Shorter project time
Easier storage archiving and documentation
WHAT CONSTITUTES A PLC
The PLC is programmed interface between the Input field elements amp output field
elements
PLC consist of
Hardware
Input Module
CPU (Central Process Unit)
Program memory
Output module
Power Supply
Software
Application Software (Logic)
Basic Software
Communication Accessories
Communication Adapter
INPUT-OUTPUT
Input and output (IO) modules connect the PLC to
sensors and actuators
Provide isolation for the low-voltage low-current
signals
Wide range of IO modules available including
Digital (logical) IO modules and Analogue (continuous) IO modules
Analogue input cards convert continuous signals via an AD converter into discrete
values for the PLC
Analogue output cards convert digital values in then PLC to continuous signals via a
DA converter
Resolution can be important in choosing an applicable card
Module receptacle for battery EEPROM
CPU statu
s LEDrsquo
sCommunicatio
ns interfa
ce
Status LEDrsquos of
the inputs
and outputs
Fixing holes for wall
mounting
Locking clip for DIN rail mounting
Analog potentiometer
Removable
connection
terminals(on 224 226)
Example for a temperature input of 0 to 100 degrees C
For 8 bit resolution the value in the PLC is 0 to 255
For 12 bit resolution the value in the PLC is 0 to 4095
For 16 bit resolution the value in the PLC is 0 to 32768
SPECIAL MODULES
RF ID
Modem modules
Load Cell
Stepper Modules
Temperature Sensor
High Speed Counters
Position Control Cards
Field Bus Cards
o Device Net Profibus Ethernet etc
ELEMENTS OF INPUTS
Digital Inputs
push button
limit switches
Sensors
o Proximity Sensors
o Photo Sensors
Micro Switches
Toggle Switches
Analog Inputs
Pressure Transmitters
Flow Transmitter
Level Transmitter
Thermo Couples
Load Cell
ELEMENTS OF OUTPUTS
Digital Outputs
Relays
Contactors
Indication Lamps
Valves
Analog Outputs
Flow Control Valves
Pressure Control Valves
Drive Inputs
BASIC ELEMENTS OF A PROGRAM
A program block is composed of executable code and comments The executable codes consist of a main program and any subroutines or interrupt routines The code is compiled and downloaded to the S7-200 the program comments are not You can use the organizational elements (main program subroutines and interrupt routines) to structure your control program
Main ProgramThe main body of the program contains the instructions that control your application The S7-200 executes these instructions sequentially once per scan cycle The main program is also referred to as OB1
SubroutinesThese optional elements of your program are executed only when called by the main program by an interrupt routine or by another subroutine Subroutines are useful in cases where you want to execute a function repeatedly Rather than rewriting the logic for each place in the main program where you want the function to occur you can write the logic once in a subroutine and call the subroutine as many times as needed during the main program Subroutines provide several benefits
1048600 Using subroutines reduces the overall size of your program 1048600 Using subroutines decreases your scan time because you have moved the code out of the main program The S7-200 evaluates the code in the main program every scan cycle whether the code is executed or not but the S7-200 evaluates the code in the subroutine only when you call the subroutine and does not evaluate the code during the scans in which the subroutine is not called 1048600 Using subroutines creates code that is portable You can isolate the code for a function in a subroutine and then copy that subroutine into other programs with Interrupt RoutinesThese optional elements of your program react to specific interrupt events You design an interrupt routine to handle a pre-defined interrupt event Whenever the specified event occurs the S7-200 executes the interrupt routineThe interrupt routines are not called by your main program You associate an interrupt routine with an interrupt event and the S7-200 executes the instructions in the interrupt routine only on each occurrence of the interrupt event Other Elements of the ProgramOther blocks contain information for the S7-200 You can choose to download these blocks when you download your programSystem BlockThe system block allows you to configure different hardware options for the S7-200Data BlockThe data block stores the values for different variables (V memory) used by your program You can use the data block to enter initial values for the data
PROGRAMMING LANGUAGES IN PLC
IL (Instruction List) ndash mnemonic programming
LD (Ladder Diagram) ndash Relay logic
ST (Structured Text) ndash A C like programming language
FDB (Functional Block Diagram) ndash Graphical dataflow programming language
SFC (Sequential Flow Chart) ndash Graphical method for structured programs
Basic PLC Memory
Memory on a PLC is separated into 3 main areas
LOAD Memory
Can be RAM (dynamic) or EEPROM (retentive)
Used to store user programs
WORK Memory
Memory is RAM
When PLC starts Program is copied from LOAD memory to
WORK memory The program is then executed from Work
memory
SYSTEM Memory
Memory is RAM
Is used by micro-controller to implement counters timers interrupt
stacks etc
Contains a bit for each D I0
Contains ldquoMarker Memoryrdquo Marker memory is a free area of RAM
that can be used by the programmer
Contains ldquoProcess Input and Output Imagesrdquo Periodically the PLC
will store the states of the inputs to the Process Input Image and
Process Output Image to the output
SELECTION OF A PLC
Selection of PLC Based on
No of Inputs amp Outputs
Input Voltage
Memory
Scan Time
Special IO modules
Expansion Capabilities
Stand alone or Networked
Communication Capabilities
HOW PLC WORKS
Step 1-CHECKING INPUT STATUS
o PLC Scans each input
o Records the data in work memory
Step 2-EXECUTE PROGRAM
o PLC goes through the program logic step by step
o PLC executes the program depending on input status
o Write the output image in work memory
Step 3-UPDATE OUTPUT STATUS
o Changes the statues of the output onoff
o Again starts the cycle from step one
FEATURES OF S7-200
Allows Your Program to Immediately Read or Write the IO
Allows Your Program to Interrupt the Scan Cycle
Allows You to Allocate Processing Time for Communications
Tasks
Allows You to Set the States of Digital Outputs for Stop
CHECK
INPUT STATUS
EXECUTE
PROGRAM
UPDATE
OUTPUT STATUS
Mode
Allows You to Define Memory to Be Retained on Loss of Power
Allows You to Filter the Digital Inputs
Allows You to Filter the Analog Inputs
Allows You to Catch Pulses of Short Duration
Provides Password Protection
Provides Analog Adjustment Potentiometers
Provides High-speed IO
TECHNICAL FEATURES OF S7-200
Several models of CPUrsquos
o CPU 221 6in4out 2Kw program
o CPU 222 8in6out 2Kw program
o CPU 224 14in10out 4Kw program
o CPU 226 24in16out 4Kw program
Up to 256 digital input-outputs
Up to 32 analog channels
256 timers 256 counters
Built-in EEPROM memory
Real-time clockcalendar
Built-in communications
Password protection
Memory module
Removable input-output connectors
Wide range of expansion modules
o 8 pt input and output
o 4488 amp1616 inout combination
o 4 channel analog in 2 channel analog out
o 4 ch1ch analog inout combination
o 2 channel RTD in
o 4 channel thermocouple in
o PROFIBUS-DP Slave
o AS Interface master
SELECTING THE OPERATING MODE FOR THE S7- 200 CPU
The S7-200 has two modes of operation STOP mode and RUN mode The status LED on the front of the CPU indicates the current mode of operation In STOP mode the S7-200 is not executing the program and you can download a program or the CPU configuration In RUN mode the S7-200 is running the program
1048600 The S7-200 provides a mode switch for changing the mode of operation You can use the mode switch (located under the front access door of the S7-200) to manually select the operating mode setting the mode switch to STOP mode stops the execution of the program setting the mode switch to RUN mode starts the execution of the program and setting the mode switch to TERM (terminal) mode does not change the operating mode
If a power cycle occurs when the mode switch is set to either STOP or TERM the
S7-200 goes automatically to STOP mode when power is restored If a power cycle occurs when the mode switch is set to RUN the S7-200 goes to RUN mode when power is restored
1048600 STEP 7--MicroWIN allows you to change the operating mode of the online S7-200 To enable the software to change the operating mode you must manually set the mode switch on the S7-200 to either TERM or RUN You can use the PLC gt STOP or PLC gt RUN menu commands or the associated buttons on the toolbar to change the operating mode
1048600 You can insert the STOP instruction in your program to change the S7-200 to STOP mode This allows you to halt the execution of your program based on the program logic
ERRORS IN S7-200
Non-Fatal Errors
Non-fatal errors are those indicating problems with the construction of the user program with the execution of an instruction in the user program and with expansion IO modules You can use STEP 7--MicroWIN to view the error codes that were generated by the non-fatal error There are three basic categories of non-fatal errors
Program-compile errorsThe S7-200 compiles the program as it downloads If the S7-200 detects that the program violates a compilation rule the download is aborted and an error code is generated (A program that was already downloaded to the S7-200 would still exist in the EEPROM and would not be lost) After you correct your program you can download it again
IO errorsAt startup the S7-200 reads the IO configuration from each module During normal operation the S7-200 periodically checks the status of each module and compares it against the configuration obtained during startup If the S7-200 detects a difference the S7-200 sets the configuration error bit in the module error register The S7-200 does not read input data from or write output data to that module until the module configuration again matches the one obtained at startupThe module status information is stored in special memory (SM) bits Your program can monitor and evaluate these bits Refer to Appendix D for more information about the SM bits used for reporting IO errors SM50 is the global IO error bit and remains set while an error condition exists on an expansion module
Program execution errorsYour program can create error conditions while being executed These errors can result from improper use of an instruction or from the processing of invalid data by an instruction For example an indirect-address pointer that was valid when the program compiled could be modified during the execution of the program to point to an out-of-range address This is an example of a run-time programming problem SM43 is setupon the occurrence of a run-time programming problem and remains set while the S7-200 is in RUN mode Program execution error information is stored in special memory (SM) bits Your program can monitor and evaluate these bits The S7-200 does not change to STOP mode when it detects a non-fatal error It only logs the event in SM memory and continues with the execution of your program However you can design your program to force the S7-200 to STOP mode when a non-fatal error is detected
Fatal Errors
Fatal errors cause the S7-200 to stop the execution of your program Depending upon the severity of the fatal error it can render the S7-200 incapable of performing any or all functions The objective for handling fatal errors is to bring the S7-200 to a safe state from which the S7-200 can respond to interrogations about the existing error conditions When a fatal error is detected the S7-200 changes to STOP mode turns on the System Fault LED and the STOP LED overrides the output table and turns off the outputsThe S7-200 remains in this condition until the fatal error condition is corrected
Once you have made the changes to correct the fatal error condition use one of the following methods to restart the S7-200 1048600 Turn the power off and then on 1048600 Change the mode switch from RUN or TERM to STOP 1048600 Select the PLC gt Power-Up Reset menu command from STEP 7--MicroWIN
to restart the S7-200This forces the S7-200 to restart and clear any fatal errors
Restarting the S7-200 clears the fatal error condition and performs power-up diagnostic testing to verify that the fatal error has been corrected If another fatal error condition is found the S7-200 again sets the fault LED indicating that an error still exists Otherwise the S7-200 begins normal operation
Some error conditions can render the S7-200 incapable of communication In these cases you cannot view the error code from the S7-200 These types of errors indicate hardware failures that require the S7-200 to be repaired they cannot be fixed by changes to the program or clearing the memory of the S7-200
APPLICATIONS OF S7-200
Conveyer Systems
Elevators
Test Stations
Placement Systems
Woodworking Machinery
Packaging Equipment
Car Wash Automation
Remote Monitoring And Controlling For Water Wastewater
FEATURES OF LADDER DIAGRAMS
The LAD editor displays the program as a graphical representation similar to electrical wiring diagrams
Ladder programs allow the program to emulate the flow of electric current from a power source through a series of logical input conditions that in turn enable logical output conditions
A LAD program includes a left power rail that is energized Contacts that are closed allow energy to flow through them to the next element and contacts that are open block that energy flow
The logic is separated into networks The program is executed one network at a time from left to right and then top to bottom as dictated by the program Figure shows an example of a LAD program
The various instructions are represented by graphic symbols and include three basic forms
Contacts represent logic input conditions such as switches buttons or internal conditions
Coils usually represent logic output results such as lamps motor starters interposing relays or internal output conditions
Boxes represent additional instructions such as timers counters or math instructions Figure Sample LAD Program
Consider these main points when you select the LAD editor 1048600 Ladder logic is easy for beginning programmers to use 1048600 Graphical representation is easy to understand and is popular around the world 1048600 The LAD editor can be used with both the SIMATIC and IEC 1131--3 Instruction sets
1048600 You can always use the STL editor to display a program created with
the SIMATIC LAD editor
COMPONENTS LIST
Cardboard of 4050 sqcm
PLC S7-200
Sensors
LEDS
Buzzers
Motor
Contactors
Power supply
12v DC battery
Connecting wires
PPI Cable
SENSORS
A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact A proximity sensor often emits an electromagnetic or electrostatic field or a beam of electromagnetic radiation (infrared for instance) and looks for changes in the field or return signal The object being sensed is often referred to as the proximity sensors target Different
proximity sensor targets demand different sensors For example a capacitive or photoelectric sensor might be suitable for a plastic target an inductive proximity sensor requires a metal target
The maximum distance that this sensor can detect is defined nominal range Some sensors have adjustments of the nominal range or means to report a graduated detection distance
Proximity sensors can have a high reliability and long functional life because of the absence of mechanical parts and lack of physical contact between sensor and the sensed object
IEC 60947-5-2 defines the technical details of proximity sensors
A proximity sensor adjusted to a very short range is often used as a touch switch
Applications
Car bumpers that sense distance to nearby cars for parking
Ground proximity warning system for aviation safety Vibration Position measurements of rotating shafts in
machinery Sheet break sensing in paper machine Anti-aircraft artillery
LEDS
Example Circuit symbol
FunctionLEDs emit light when an electric current passes through them
Testing an LED
Never connect an LED directly to a battery or power supply
LEDs must have a resistor in series to limit the current to a safe value for quick testing purposes a 1k resistor is suitable for most LEDs if your supply voltage is 12V or less Remember to connect the LED the correct way round
Sizes Shapes and Viewing angles of LEDs
LEDs are available in a wide variety of sizes and shapes The standard LED has a round cross-section of 5mm diameter and this is probably the best type for general use but 3mm round LEDs are also popular
Round cross-section LEDs are frequently used and they are very easy to install on boxes by drilling a hole of the LED diameter adding a spot of glue will help to hold the LED if necessary LED clips are also available to secure LEDs in holes Other cross-section shapes include square rectangular and triangular
As well as a variety of colours sizes and shapes LEDs also vary in their viewing angle This tells you how much the beam of light spreads out Standard LEDs have a viewing angle of 60deg but others have a narrow beam of 30deg or less
Calculating an LED resistor value
An LED must have a resistor connected in series to limit the current through the LED otherwise it will burn out almost instantly
The resistor value R is given by
R = (VS - VL) I
VS = supply voltage VL = LED voltage (usually 2V but 4V for blue and white LEDs) I = LED current (eg 20mA) this must be less than the maximum permitted
If the calculated value is not available choose the nearest standard resistor value which is greater so that the current will be a little less than you chose In fact you may wish to choose a greater resistor value to reduce the current (to increase battery life for example) but this will make the LED less bright
Working out the LED resistor formula using Ohms law
Ohms law says that the resistance of the resistor R = VI where V = voltage across the resistor (= VS - VL in this case) I = the current through the resistor
So R = (VS - VL) I
BUZZERS
A buzzer or beeper (BUZZERS) is a signalling device usually electronic typically used in automobiles household appliances such as a microwave oven or game shows It most commonly consists of a number of switches or sensors connected to a control unit that determines if and which button was pushed or a preset time has lapsed and usually illuminates a light on the appropriate button or control panel and sounds a warning in the form of a continuous or intermittent buzzing
or beeping sound Initially this device was based on an electromechanical system which was identical to an electric bell without the metal gong (which makes the ringing noise) Often these units were anchored to a wall or ceiling and used the ceiling or wall as a sounding board Another implementation with some AC-connected devices was to implement a circuit to make the AC current into a noise loud enough to drive a loudspeaker and hook this circuit up to a cheap 8-ohm speaker Nowadays it is more popular to use a ceramic-based piezoelectric sounder which makes a high-pitched tone Usually these were hooked up to driver circuits which varied the pitch of the sound or pulsed the sound on and off
The word buzzer comes from the rasping noise that buzzers made when they were electromechanical devices operated from stepped-down AC line voltage at 50 or 60 cycles Other sounds commonly used to indicate that a button has been pressed are a ring or a beep
MOTORS
An electric motor is a device using electrical energy to produce mechanical energy nearly always by the interaction of magnetic fields and current-carrying conductors The reverse process that of using mechanical energy to produce electrical energy is accomplished by a generator or dynamo Traction motors used on vehicles often perform both tasks
Electric motors are found in myriad uses such as industrial fans blowers and pumps machine tools household appliances power tools and computer disk drives among
many other applications Electric motors may be operated by direct current from a battery in a portable device or motor vehicle or from alternating current from a central electrical distribution grid The smallest motors may be found in electric wristwatches Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses The very largest electric motors are used for propulsion of large ships and for such purposes as pipeline compressors with ratings in the thousands of kilowatts Electric motors may be classified by the source of electric power by their internal construction and by application
The physical principle of production of mechanical force by the interaction of an electric current and a magnetic field was known as early as 1821 Electric motors of increasing efficiency were constructed throughout the 19th century but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks
CONNECTORS
A DC connector is an electrical connector for
supplying direct current (DC) power DC connectors
are poorly standardized compared to domestic AC
power plugs and sockets DC plug is a common name
used for one common type of cylindrical two-conductor
plug available in a range of sizes and used to power
small pieces of electronic equipment It is also used to
describe some older multi-pin plugs
Several competing standards exist for DC plugs and in some cases incompatible plugs
will fit together to avoid damaging equipment these conditions must be true
Voltage must match
Polarity is correct
Current ratings are sufficient
Power supply filtering and stability is adequate
for the equipment being powered
Non-matching connectors are forced together
12V DC BATTERY
Features
Less than a 12 volt self discharge per 6 months 4 ea 12Vdc outputs 20 AmpHours Built-charger Digital Voltmeter
Description
This unit supplies a full 12Vdc at 20 AmpHours Designed for the officer that needs a power source that can be charged from 115Ac source or on the way to a incident from the car
The battery source has a very low self discharge rate which makes it perfect for law enforcement use The battery can set on the shelf for more than 6 months without recharging
Everyone knows when you grab a battery operated device the internal battery always requires several hours of charging before using The new voltage indicator reads out voltage to one hundredth of a volt for accurate operation The four outputs are 21mm plug Quick terminals and Cigarette lighter jack amp PT02 (Mil Spec) This model also allows powering
12Vdc sources while plugged in to 115Vac ldquoIts a UPSrdquo
SPECIFICATIONS OF COMPONENTS USED
PLC S7-200
INPUT POWER 230V AC 50 Hz
INPUTS 24 DC INPUTS
OUTPUTS 16 DC OUTPUTS
PROGRAM MEMORY 24
DATA MEMORY 10KB
EXPANSION MODULES 7
COMMUNICATION PORTS 2 RS 485
DIGITAL IO IMAGE SIZE 256(128 in 128 out)
EXECUTION SPEED 022microsecondsinstruction
SENSORS
SENSING RANGE 3mm
HOUSING MATERIAL Brass Nickel Plated
OPERATING VOLTAGE 10-30V
OPERATING CURRENT lt200mA
CONNECTION TYPE Cable
LEDS
DIAMETER 5mm
MAXIMUM VOLTAGE 1V
MAXIMUM CURRENT 10mA
INTENSITY
BUZZERS
OPERATING VOLTAGE30Vp-p
RATED FREQUENCY2000Hz 500Hz
OPERATING TEMP RANGE -20 to 60 degree
SOUND OUTPUT70 dB min10 cm
MOTOR
TOTAL LENGTH 46mm MOTOR DIAMETER 36mm MOTOR LENGTH 25mm DC SUPPLY 4 to 12V RPM 100 BRUSH TYPE Precious metal GEAR HEAD DIAMETER 37mm GEAR HEAD LENGTH 21mm OUTPUT SHAFT Centered SHAFT DIAMETER 4mm and 6mm
SHAFT LENGTH 22mm
- Block diagram of plc
- Applications
-
- Function
- Testing an LED
- Sizes Shapes and Viewing angles of LEDs
- Calculating an LED resistor value
-
- Working out the LED resistor formula using Ohms law
-
One of the advantages of implementing logical control in software rather than in hardware is that input signals can be re-used as many times in the program as is necessary Another advantage of PLCs that simply cannot be duplicated by electromechanical relays is remote monitoring and control via digital computer networks Because a PLC is nothing more than a special-purpose digital computer it has the ability to communicate with other computers rather easily
2 HISTORY
21 ORIGIN
The PLC was invented in response to the needs of the American automotive manufacturing industry Programmable controllers were initially adopted by the automotive industry where software revision replaced the re-wiring of hard-wired control panels when production models changed
Before the PLC control sequencing and safety interlock logic for manufacturing automobiles was accomplished using hundreds or thousands of relays cam timers and drum sequencers and dedicated closed-loop controllers The process for updating such facilities for the yearly model change-over was very time consuming and expensive as the relay systems needed to be rewired by skilled electricians
In 1968 GM Hydramatic (the automatic transmission division of General Motors) issued a request for proposal for an electronic replacement for hard-wired relay systems
The winning proposal came from Bedford Associates of Bedford Massachusetts The first PLC designated the 084 because it was Bedford Associates eighty-fourth project was the result Bedford Associates started a new company dedicated to developing manufacturing selling and servicing this new product MODICON which stood for MOdular DIgital CONtroller One of the people who worked on that project was Dick Morley who is considered to be the father of the PLC The MODICON brand was sold in 1977 to Gould Electronics and later acquired by German Company AEG and then by French Schneider Electric the current owner
One of the very first 084 models built is now on display at Modicons headquarters in North Andover Massachusetts It was presented to Modicon by GM when the unit was retired after nearly twenty years of uninterrupted service Modicon used the 84 moniker at the end of its product range until the 984 made its appearance
The automotive industry is still one of the largest users of PLCs
22 DEVELOPMENT
Early PLCs were designed to replace relay logic systems These PLCs were programmed in ladder logic which strongly resembles a schematic diagram of relay logic Modern PLCs can be programmed in a variety of ways from ladder logic to more traditional programming languages such as BASIC and C Another method is State Logic a very high-level programming language designed to program PLCs based on state transition diagrams
Many of the earliest PLCs expressed all decision making logic in simple ladder logic which appeared similar to electrical schematic diagrams This program notation was chosen to reduce training demands for the existing technicians Other early PLCs used a form of instruction list programming based on a stack-based logic solver
23 PROGRAMMING
Early PLCs up to the mid-1980s were programmed using proprietary programming panels or special-purpose programming terminals which often had dedicated function keys representing the various logical elements of PLC programs Programs were stored on cassette tape cartridges Facilities for printing and documentation were very minimal due to lack of memory capacity The very oldest PLCs used non-volatile magnetic core memory
24 FUNCTIONALITY
The functionality of the PLC has evolved over the years to include sequential relay control motion control process control distributed control systems and networking The data handling storage processing power and communication capabilities of some modern PLCs are approximately equivalent to desktop computers PLC-like programming combined with remote IO hardware allow a general-purpose desktop computer to overlap some PLCs in certain applications
PLC ARCHITECTURE
CPU
Power Supply
Memory
Input Blocks
Output Blocks
Communications
Expansion Connections
BLOCK DIAGRAM OF PLC
SENSORS
PLC COMPARED WITH OTHER CONTROL SYSTEMS
PLCs are well-adapted to a range of automation tasks These are typically industrial processes in manufacturing where the cost of developing and maintaining the automation system is high relative to the total cost of the automation and where changes to the system would be expected during its operational life PLCs contain input and output devices compatible with industrial pilot devices and controls little electrical design is required and the design problem centers on expressing the desired sequence of operations in ladder logic (or function chart) notation PLC applications are typically highly customized systems so the cost of a packaged PLC is low compared to the cost of a specific custom-built controller design On the other hand in the case of mass-produced goods customized control systems are economic due to the lower cost of the components which can be optimally chosen instead of a generic solution and where the non-recurring engineering charges are spread over thousands or millions of units
For high volume or very simple fixed automation tasks different techniques are used A microcontroller-based design would be appropriate where hundreds or thousands of units will be produced and so the development cost (design of power supplies and inputoutput hardware) can be spread over many sales and where the end-user would not need to alter the control Automotive applications are an example millions of units are built each year and very few end-users alter the programming of these controllers
Power supply
Input
Module
Memory
Processor
Output
Module
However some specialty vehicles such as transit busses economically use PLCs instead of custom-designed controls because the volumes are low and the development cost would be uneconomic
Very complex process control such as used in the chemical industry may require algorithms and performance beyond the capability of even high-performance PLCs Very high-speed or precision controls may also require customized solutions for example aircraft flight controls
Programmable controllers are widely used in motion control positioning control and torque control Some manufacturers produce motion control units to be integrated with PLC so that G-code (involving a CNC machine) can be used to instruct machine movements
PLCs may include logic for single-variable feedback analog control loop a proportional integral derivative or PID controller A PID loop could be used to control the temperature of a manufacturing process for example Historically PLCs were usually configured with only a few analog control loops where processes required hundreds or thousands of loops a distributed control system (DCS) would instead be used As PLCs have become more powerful the boundary between DCS and PLC applications has become less distinct
PLCs have similar functionality as Remote Terminal Units An RTU however usually does not support control algorithms or control loops As hardware rapidly becomes more powerful and cheaper RTUs PLCs and DCSs are increasingly beginning to overlap in responsibilities The industry has standardized on the IEC 61131-3 functional block language for creating programs to run on RTUs and PLCs although nearly all vendors also offer proprietary alternatives and associated development environments
DISADVANTAGES OF lsquoHARD WIRED LOGIC CONTROLrsquo
Bulky panels
Complex wiring
Longer project time
Difficult maintenance and troubleshooting
ADVANTAGES OF lsquoPLCSrsquo
Reduced space
Ease of maintenance
Economical
Greater life amp reliability
Tremendous flexibility
Shorter project time
Easier storage archiving and documentation
WHAT CONSTITUTES A PLC
The PLC is programmed interface between the Input field elements amp output field
elements
PLC consist of
Hardware
Input Module
CPU (Central Process Unit)
Program memory
Output module
Power Supply
Software
Application Software (Logic)
Basic Software
Communication Accessories
Communication Adapter
INPUT-OUTPUT
Input and output (IO) modules connect the PLC to
sensors and actuators
Provide isolation for the low-voltage low-current
signals
Wide range of IO modules available including
Digital (logical) IO modules and Analogue (continuous) IO modules
Analogue input cards convert continuous signals via an AD converter into discrete
values for the PLC
Analogue output cards convert digital values in then PLC to continuous signals via a
DA converter
Resolution can be important in choosing an applicable card
Module receptacle for battery EEPROM
CPU statu
s LEDrsquo
sCommunicatio
ns interfa
ce
Status LEDrsquos of
the inputs
and outputs
Fixing holes for wall
mounting
Locking clip for DIN rail mounting
Analog potentiometer
Removable
connection
terminals(on 224 226)
Example for a temperature input of 0 to 100 degrees C
For 8 bit resolution the value in the PLC is 0 to 255
For 12 bit resolution the value in the PLC is 0 to 4095
For 16 bit resolution the value in the PLC is 0 to 32768
SPECIAL MODULES
RF ID
Modem modules
Load Cell
Stepper Modules
Temperature Sensor
High Speed Counters
Position Control Cards
Field Bus Cards
o Device Net Profibus Ethernet etc
ELEMENTS OF INPUTS
Digital Inputs
push button
limit switches
Sensors
o Proximity Sensors
o Photo Sensors
Micro Switches
Toggle Switches
Analog Inputs
Pressure Transmitters
Flow Transmitter
Level Transmitter
Thermo Couples
Load Cell
ELEMENTS OF OUTPUTS
Digital Outputs
Relays
Contactors
Indication Lamps
Valves
Analog Outputs
Flow Control Valves
Pressure Control Valves
Drive Inputs
BASIC ELEMENTS OF A PROGRAM
A program block is composed of executable code and comments The executable codes consist of a main program and any subroutines or interrupt routines The code is compiled and downloaded to the S7-200 the program comments are not You can use the organizational elements (main program subroutines and interrupt routines) to structure your control program
Main ProgramThe main body of the program contains the instructions that control your application The S7-200 executes these instructions sequentially once per scan cycle The main program is also referred to as OB1
SubroutinesThese optional elements of your program are executed only when called by the main program by an interrupt routine or by another subroutine Subroutines are useful in cases where you want to execute a function repeatedly Rather than rewriting the logic for each place in the main program where you want the function to occur you can write the logic once in a subroutine and call the subroutine as many times as needed during the main program Subroutines provide several benefits
1048600 Using subroutines reduces the overall size of your program 1048600 Using subroutines decreases your scan time because you have moved the code out of the main program The S7-200 evaluates the code in the main program every scan cycle whether the code is executed or not but the S7-200 evaluates the code in the subroutine only when you call the subroutine and does not evaluate the code during the scans in which the subroutine is not called 1048600 Using subroutines creates code that is portable You can isolate the code for a function in a subroutine and then copy that subroutine into other programs with Interrupt RoutinesThese optional elements of your program react to specific interrupt events You design an interrupt routine to handle a pre-defined interrupt event Whenever the specified event occurs the S7-200 executes the interrupt routineThe interrupt routines are not called by your main program You associate an interrupt routine with an interrupt event and the S7-200 executes the instructions in the interrupt routine only on each occurrence of the interrupt event Other Elements of the ProgramOther blocks contain information for the S7-200 You can choose to download these blocks when you download your programSystem BlockThe system block allows you to configure different hardware options for the S7-200Data BlockThe data block stores the values for different variables (V memory) used by your program You can use the data block to enter initial values for the data
PROGRAMMING LANGUAGES IN PLC
IL (Instruction List) ndash mnemonic programming
LD (Ladder Diagram) ndash Relay logic
ST (Structured Text) ndash A C like programming language
FDB (Functional Block Diagram) ndash Graphical dataflow programming language
SFC (Sequential Flow Chart) ndash Graphical method for structured programs
Basic PLC Memory
Memory on a PLC is separated into 3 main areas
LOAD Memory
Can be RAM (dynamic) or EEPROM (retentive)
Used to store user programs
WORK Memory
Memory is RAM
When PLC starts Program is copied from LOAD memory to
WORK memory The program is then executed from Work
memory
SYSTEM Memory
Memory is RAM
Is used by micro-controller to implement counters timers interrupt
stacks etc
Contains a bit for each D I0
Contains ldquoMarker Memoryrdquo Marker memory is a free area of RAM
that can be used by the programmer
Contains ldquoProcess Input and Output Imagesrdquo Periodically the PLC
will store the states of the inputs to the Process Input Image and
Process Output Image to the output
SELECTION OF A PLC
Selection of PLC Based on
No of Inputs amp Outputs
Input Voltage
Memory
Scan Time
Special IO modules
Expansion Capabilities
Stand alone or Networked
Communication Capabilities
HOW PLC WORKS
Step 1-CHECKING INPUT STATUS
o PLC Scans each input
o Records the data in work memory
Step 2-EXECUTE PROGRAM
o PLC goes through the program logic step by step
o PLC executes the program depending on input status
o Write the output image in work memory
Step 3-UPDATE OUTPUT STATUS
o Changes the statues of the output onoff
o Again starts the cycle from step one
FEATURES OF S7-200
Allows Your Program to Immediately Read or Write the IO
Allows Your Program to Interrupt the Scan Cycle
Allows You to Allocate Processing Time for Communications
Tasks
Allows You to Set the States of Digital Outputs for Stop
CHECK
INPUT STATUS
EXECUTE
PROGRAM
UPDATE
OUTPUT STATUS
Mode
Allows You to Define Memory to Be Retained on Loss of Power
Allows You to Filter the Digital Inputs
Allows You to Filter the Analog Inputs
Allows You to Catch Pulses of Short Duration
Provides Password Protection
Provides Analog Adjustment Potentiometers
Provides High-speed IO
TECHNICAL FEATURES OF S7-200
Several models of CPUrsquos
o CPU 221 6in4out 2Kw program
o CPU 222 8in6out 2Kw program
o CPU 224 14in10out 4Kw program
o CPU 226 24in16out 4Kw program
Up to 256 digital input-outputs
Up to 32 analog channels
256 timers 256 counters
Built-in EEPROM memory
Real-time clockcalendar
Built-in communications
Password protection
Memory module
Removable input-output connectors
Wide range of expansion modules
o 8 pt input and output
o 4488 amp1616 inout combination
o 4 channel analog in 2 channel analog out
o 4 ch1ch analog inout combination
o 2 channel RTD in
o 4 channel thermocouple in
o PROFIBUS-DP Slave
o AS Interface master
SELECTING THE OPERATING MODE FOR THE S7- 200 CPU
The S7-200 has two modes of operation STOP mode and RUN mode The status LED on the front of the CPU indicates the current mode of operation In STOP mode the S7-200 is not executing the program and you can download a program or the CPU configuration In RUN mode the S7-200 is running the program
1048600 The S7-200 provides a mode switch for changing the mode of operation You can use the mode switch (located under the front access door of the S7-200) to manually select the operating mode setting the mode switch to STOP mode stops the execution of the program setting the mode switch to RUN mode starts the execution of the program and setting the mode switch to TERM (terminal) mode does not change the operating mode
If a power cycle occurs when the mode switch is set to either STOP or TERM the
S7-200 goes automatically to STOP mode when power is restored If a power cycle occurs when the mode switch is set to RUN the S7-200 goes to RUN mode when power is restored
1048600 STEP 7--MicroWIN allows you to change the operating mode of the online S7-200 To enable the software to change the operating mode you must manually set the mode switch on the S7-200 to either TERM or RUN You can use the PLC gt STOP or PLC gt RUN menu commands or the associated buttons on the toolbar to change the operating mode
1048600 You can insert the STOP instruction in your program to change the S7-200 to STOP mode This allows you to halt the execution of your program based on the program logic
ERRORS IN S7-200
Non-Fatal Errors
Non-fatal errors are those indicating problems with the construction of the user program with the execution of an instruction in the user program and with expansion IO modules You can use STEP 7--MicroWIN to view the error codes that were generated by the non-fatal error There are three basic categories of non-fatal errors
Program-compile errorsThe S7-200 compiles the program as it downloads If the S7-200 detects that the program violates a compilation rule the download is aborted and an error code is generated (A program that was already downloaded to the S7-200 would still exist in the EEPROM and would not be lost) After you correct your program you can download it again
IO errorsAt startup the S7-200 reads the IO configuration from each module During normal operation the S7-200 periodically checks the status of each module and compares it against the configuration obtained during startup If the S7-200 detects a difference the S7-200 sets the configuration error bit in the module error register The S7-200 does not read input data from or write output data to that module until the module configuration again matches the one obtained at startupThe module status information is stored in special memory (SM) bits Your program can monitor and evaluate these bits Refer to Appendix D for more information about the SM bits used for reporting IO errors SM50 is the global IO error bit and remains set while an error condition exists on an expansion module
Program execution errorsYour program can create error conditions while being executed These errors can result from improper use of an instruction or from the processing of invalid data by an instruction For example an indirect-address pointer that was valid when the program compiled could be modified during the execution of the program to point to an out-of-range address This is an example of a run-time programming problem SM43 is setupon the occurrence of a run-time programming problem and remains set while the S7-200 is in RUN mode Program execution error information is stored in special memory (SM) bits Your program can monitor and evaluate these bits The S7-200 does not change to STOP mode when it detects a non-fatal error It only logs the event in SM memory and continues with the execution of your program However you can design your program to force the S7-200 to STOP mode when a non-fatal error is detected
Fatal Errors
Fatal errors cause the S7-200 to stop the execution of your program Depending upon the severity of the fatal error it can render the S7-200 incapable of performing any or all functions The objective for handling fatal errors is to bring the S7-200 to a safe state from which the S7-200 can respond to interrogations about the existing error conditions When a fatal error is detected the S7-200 changes to STOP mode turns on the System Fault LED and the STOP LED overrides the output table and turns off the outputsThe S7-200 remains in this condition until the fatal error condition is corrected
Once you have made the changes to correct the fatal error condition use one of the following methods to restart the S7-200 1048600 Turn the power off and then on 1048600 Change the mode switch from RUN or TERM to STOP 1048600 Select the PLC gt Power-Up Reset menu command from STEP 7--MicroWIN
to restart the S7-200This forces the S7-200 to restart and clear any fatal errors
Restarting the S7-200 clears the fatal error condition and performs power-up diagnostic testing to verify that the fatal error has been corrected If another fatal error condition is found the S7-200 again sets the fault LED indicating that an error still exists Otherwise the S7-200 begins normal operation
Some error conditions can render the S7-200 incapable of communication In these cases you cannot view the error code from the S7-200 These types of errors indicate hardware failures that require the S7-200 to be repaired they cannot be fixed by changes to the program or clearing the memory of the S7-200
APPLICATIONS OF S7-200
Conveyer Systems
Elevators
Test Stations
Placement Systems
Woodworking Machinery
Packaging Equipment
Car Wash Automation
Remote Monitoring And Controlling For Water Wastewater
FEATURES OF LADDER DIAGRAMS
The LAD editor displays the program as a graphical representation similar to electrical wiring diagrams
Ladder programs allow the program to emulate the flow of electric current from a power source through a series of logical input conditions that in turn enable logical output conditions
A LAD program includes a left power rail that is energized Contacts that are closed allow energy to flow through them to the next element and contacts that are open block that energy flow
The logic is separated into networks The program is executed one network at a time from left to right and then top to bottom as dictated by the program Figure shows an example of a LAD program
The various instructions are represented by graphic symbols and include three basic forms
Contacts represent logic input conditions such as switches buttons or internal conditions
Coils usually represent logic output results such as lamps motor starters interposing relays or internal output conditions
Boxes represent additional instructions such as timers counters or math instructions Figure Sample LAD Program
Consider these main points when you select the LAD editor 1048600 Ladder logic is easy for beginning programmers to use 1048600 Graphical representation is easy to understand and is popular around the world 1048600 The LAD editor can be used with both the SIMATIC and IEC 1131--3 Instruction sets
1048600 You can always use the STL editor to display a program created with
the SIMATIC LAD editor
COMPONENTS LIST
Cardboard of 4050 sqcm
PLC S7-200
Sensors
LEDS
Buzzers
Motor
Contactors
Power supply
12v DC battery
Connecting wires
PPI Cable
SENSORS
A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact A proximity sensor often emits an electromagnetic or electrostatic field or a beam of electromagnetic radiation (infrared for instance) and looks for changes in the field or return signal The object being sensed is often referred to as the proximity sensors target Different
proximity sensor targets demand different sensors For example a capacitive or photoelectric sensor might be suitable for a plastic target an inductive proximity sensor requires a metal target
The maximum distance that this sensor can detect is defined nominal range Some sensors have adjustments of the nominal range or means to report a graduated detection distance
Proximity sensors can have a high reliability and long functional life because of the absence of mechanical parts and lack of physical contact between sensor and the sensed object
IEC 60947-5-2 defines the technical details of proximity sensors
A proximity sensor adjusted to a very short range is often used as a touch switch
Applications
Car bumpers that sense distance to nearby cars for parking
Ground proximity warning system for aviation safety Vibration Position measurements of rotating shafts in
machinery Sheet break sensing in paper machine Anti-aircraft artillery
LEDS
Example Circuit symbol
FunctionLEDs emit light when an electric current passes through them
Testing an LED
Never connect an LED directly to a battery or power supply
LEDs must have a resistor in series to limit the current to a safe value for quick testing purposes a 1k resistor is suitable for most LEDs if your supply voltage is 12V or less Remember to connect the LED the correct way round
Sizes Shapes and Viewing angles of LEDs
LEDs are available in a wide variety of sizes and shapes The standard LED has a round cross-section of 5mm diameter and this is probably the best type for general use but 3mm round LEDs are also popular
Round cross-section LEDs are frequently used and they are very easy to install on boxes by drilling a hole of the LED diameter adding a spot of glue will help to hold the LED if necessary LED clips are also available to secure LEDs in holes Other cross-section shapes include square rectangular and triangular
As well as a variety of colours sizes and shapes LEDs also vary in their viewing angle This tells you how much the beam of light spreads out Standard LEDs have a viewing angle of 60deg but others have a narrow beam of 30deg or less
Calculating an LED resistor value
An LED must have a resistor connected in series to limit the current through the LED otherwise it will burn out almost instantly
The resistor value R is given by
R = (VS - VL) I
VS = supply voltage VL = LED voltage (usually 2V but 4V for blue and white LEDs) I = LED current (eg 20mA) this must be less than the maximum permitted
If the calculated value is not available choose the nearest standard resistor value which is greater so that the current will be a little less than you chose In fact you may wish to choose a greater resistor value to reduce the current (to increase battery life for example) but this will make the LED less bright
Working out the LED resistor formula using Ohms law
Ohms law says that the resistance of the resistor R = VI where V = voltage across the resistor (= VS - VL in this case) I = the current through the resistor
So R = (VS - VL) I
BUZZERS
A buzzer or beeper (BUZZERS) is a signalling device usually electronic typically used in automobiles household appliances such as a microwave oven or game shows It most commonly consists of a number of switches or sensors connected to a control unit that determines if and which button was pushed or a preset time has lapsed and usually illuminates a light on the appropriate button or control panel and sounds a warning in the form of a continuous or intermittent buzzing
or beeping sound Initially this device was based on an electromechanical system which was identical to an electric bell without the metal gong (which makes the ringing noise) Often these units were anchored to a wall or ceiling and used the ceiling or wall as a sounding board Another implementation with some AC-connected devices was to implement a circuit to make the AC current into a noise loud enough to drive a loudspeaker and hook this circuit up to a cheap 8-ohm speaker Nowadays it is more popular to use a ceramic-based piezoelectric sounder which makes a high-pitched tone Usually these were hooked up to driver circuits which varied the pitch of the sound or pulsed the sound on and off
The word buzzer comes from the rasping noise that buzzers made when they were electromechanical devices operated from stepped-down AC line voltage at 50 or 60 cycles Other sounds commonly used to indicate that a button has been pressed are a ring or a beep
MOTORS
An electric motor is a device using electrical energy to produce mechanical energy nearly always by the interaction of magnetic fields and current-carrying conductors The reverse process that of using mechanical energy to produce electrical energy is accomplished by a generator or dynamo Traction motors used on vehicles often perform both tasks
Electric motors are found in myriad uses such as industrial fans blowers and pumps machine tools household appliances power tools and computer disk drives among
many other applications Electric motors may be operated by direct current from a battery in a portable device or motor vehicle or from alternating current from a central electrical distribution grid The smallest motors may be found in electric wristwatches Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses The very largest electric motors are used for propulsion of large ships and for such purposes as pipeline compressors with ratings in the thousands of kilowatts Electric motors may be classified by the source of electric power by their internal construction and by application
The physical principle of production of mechanical force by the interaction of an electric current and a magnetic field was known as early as 1821 Electric motors of increasing efficiency were constructed throughout the 19th century but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks
CONNECTORS
A DC connector is an electrical connector for
supplying direct current (DC) power DC connectors
are poorly standardized compared to domestic AC
power plugs and sockets DC plug is a common name
used for one common type of cylindrical two-conductor
plug available in a range of sizes and used to power
small pieces of electronic equipment It is also used to
describe some older multi-pin plugs
Several competing standards exist for DC plugs and in some cases incompatible plugs
will fit together to avoid damaging equipment these conditions must be true
Voltage must match
Polarity is correct
Current ratings are sufficient
Power supply filtering and stability is adequate
for the equipment being powered
Non-matching connectors are forced together
12V DC BATTERY
Features
Less than a 12 volt self discharge per 6 months 4 ea 12Vdc outputs 20 AmpHours Built-charger Digital Voltmeter
Description
This unit supplies a full 12Vdc at 20 AmpHours Designed for the officer that needs a power source that can be charged from 115Ac source or on the way to a incident from the car
The battery source has a very low self discharge rate which makes it perfect for law enforcement use The battery can set on the shelf for more than 6 months without recharging
Everyone knows when you grab a battery operated device the internal battery always requires several hours of charging before using The new voltage indicator reads out voltage to one hundredth of a volt for accurate operation The four outputs are 21mm plug Quick terminals and Cigarette lighter jack amp PT02 (Mil Spec) This model also allows powering
12Vdc sources while plugged in to 115Vac ldquoIts a UPSrdquo
SPECIFICATIONS OF COMPONENTS USED
PLC S7-200
INPUT POWER 230V AC 50 Hz
INPUTS 24 DC INPUTS
OUTPUTS 16 DC OUTPUTS
PROGRAM MEMORY 24
DATA MEMORY 10KB
EXPANSION MODULES 7
COMMUNICATION PORTS 2 RS 485
DIGITAL IO IMAGE SIZE 256(128 in 128 out)
EXECUTION SPEED 022microsecondsinstruction
SENSORS
SENSING RANGE 3mm
HOUSING MATERIAL Brass Nickel Plated
OPERATING VOLTAGE 10-30V
OPERATING CURRENT lt200mA
CONNECTION TYPE Cable
LEDS
DIAMETER 5mm
MAXIMUM VOLTAGE 1V
MAXIMUM CURRENT 10mA
INTENSITY
BUZZERS
OPERATING VOLTAGE30Vp-p
RATED FREQUENCY2000Hz 500Hz
OPERATING TEMP RANGE -20 to 60 degree
SOUND OUTPUT70 dB min10 cm
MOTOR
TOTAL LENGTH 46mm MOTOR DIAMETER 36mm MOTOR LENGTH 25mm DC SUPPLY 4 to 12V RPM 100 BRUSH TYPE Precious metal GEAR HEAD DIAMETER 37mm GEAR HEAD LENGTH 21mm OUTPUT SHAFT Centered SHAFT DIAMETER 4mm and 6mm
SHAFT LENGTH 22mm
- Block diagram of plc
- Applications
-
- Function
- Testing an LED
- Sizes Shapes and Viewing angles of LEDs
- Calculating an LED resistor value
-
- Working out the LED resistor formula using Ohms law
-
Before the PLC control sequencing and safety interlock logic for manufacturing automobiles was accomplished using hundreds or thousands of relays cam timers and drum sequencers and dedicated closed-loop controllers The process for updating such facilities for the yearly model change-over was very time consuming and expensive as the relay systems needed to be rewired by skilled electricians
In 1968 GM Hydramatic (the automatic transmission division of General Motors) issued a request for proposal for an electronic replacement for hard-wired relay systems
The winning proposal came from Bedford Associates of Bedford Massachusetts The first PLC designated the 084 because it was Bedford Associates eighty-fourth project was the result Bedford Associates started a new company dedicated to developing manufacturing selling and servicing this new product MODICON which stood for MOdular DIgital CONtroller One of the people who worked on that project was Dick Morley who is considered to be the father of the PLC The MODICON brand was sold in 1977 to Gould Electronics and later acquired by German Company AEG and then by French Schneider Electric the current owner
One of the very first 084 models built is now on display at Modicons headquarters in North Andover Massachusetts It was presented to Modicon by GM when the unit was retired after nearly twenty years of uninterrupted service Modicon used the 84 moniker at the end of its product range until the 984 made its appearance
The automotive industry is still one of the largest users of PLCs
22 DEVELOPMENT
Early PLCs were designed to replace relay logic systems These PLCs were programmed in ladder logic which strongly resembles a schematic diagram of relay logic Modern PLCs can be programmed in a variety of ways from ladder logic to more traditional programming languages such as BASIC and C Another method is State Logic a very high-level programming language designed to program PLCs based on state transition diagrams
Many of the earliest PLCs expressed all decision making logic in simple ladder logic which appeared similar to electrical schematic diagrams This program notation was chosen to reduce training demands for the existing technicians Other early PLCs used a form of instruction list programming based on a stack-based logic solver
23 PROGRAMMING
Early PLCs up to the mid-1980s were programmed using proprietary programming panels or special-purpose programming terminals which often had dedicated function keys representing the various logical elements of PLC programs Programs were stored on cassette tape cartridges Facilities for printing and documentation were very minimal due to lack of memory capacity The very oldest PLCs used non-volatile magnetic core memory
24 FUNCTIONALITY
The functionality of the PLC has evolved over the years to include sequential relay control motion control process control distributed control systems and networking The data handling storage processing power and communication capabilities of some modern PLCs are approximately equivalent to desktop computers PLC-like programming combined with remote IO hardware allow a general-purpose desktop computer to overlap some PLCs in certain applications
PLC ARCHITECTURE
CPU
Power Supply
Memory
Input Blocks
Output Blocks
Communications
Expansion Connections
BLOCK DIAGRAM OF PLC
SENSORS
PLC COMPARED WITH OTHER CONTROL SYSTEMS
PLCs are well-adapted to a range of automation tasks These are typically industrial processes in manufacturing where the cost of developing and maintaining the automation system is high relative to the total cost of the automation and where changes to the system would be expected during its operational life PLCs contain input and output devices compatible with industrial pilot devices and controls little electrical design is required and the design problem centers on expressing the desired sequence of operations in ladder logic (or function chart) notation PLC applications are typically highly customized systems so the cost of a packaged PLC is low compared to the cost of a specific custom-built controller design On the other hand in the case of mass-produced goods customized control systems are economic due to the lower cost of the components which can be optimally chosen instead of a generic solution and where the non-recurring engineering charges are spread over thousands or millions of units
For high volume or very simple fixed automation tasks different techniques are used A microcontroller-based design would be appropriate where hundreds or thousands of units will be produced and so the development cost (design of power supplies and inputoutput hardware) can be spread over many sales and where the end-user would not need to alter the control Automotive applications are an example millions of units are built each year and very few end-users alter the programming of these controllers
Power supply
Input
Module
Memory
Processor
Output
Module
However some specialty vehicles such as transit busses economically use PLCs instead of custom-designed controls because the volumes are low and the development cost would be uneconomic
Very complex process control such as used in the chemical industry may require algorithms and performance beyond the capability of even high-performance PLCs Very high-speed or precision controls may also require customized solutions for example aircraft flight controls
Programmable controllers are widely used in motion control positioning control and torque control Some manufacturers produce motion control units to be integrated with PLC so that G-code (involving a CNC machine) can be used to instruct machine movements
PLCs may include logic for single-variable feedback analog control loop a proportional integral derivative or PID controller A PID loop could be used to control the temperature of a manufacturing process for example Historically PLCs were usually configured with only a few analog control loops where processes required hundreds or thousands of loops a distributed control system (DCS) would instead be used As PLCs have become more powerful the boundary between DCS and PLC applications has become less distinct
PLCs have similar functionality as Remote Terminal Units An RTU however usually does not support control algorithms or control loops As hardware rapidly becomes more powerful and cheaper RTUs PLCs and DCSs are increasingly beginning to overlap in responsibilities The industry has standardized on the IEC 61131-3 functional block language for creating programs to run on RTUs and PLCs although nearly all vendors also offer proprietary alternatives and associated development environments
DISADVANTAGES OF lsquoHARD WIRED LOGIC CONTROLrsquo
Bulky panels
Complex wiring
Longer project time
Difficult maintenance and troubleshooting
ADVANTAGES OF lsquoPLCSrsquo
Reduced space
Ease of maintenance
Economical
Greater life amp reliability
Tremendous flexibility
Shorter project time
Easier storage archiving and documentation
WHAT CONSTITUTES A PLC
The PLC is programmed interface between the Input field elements amp output field
elements
PLC consist of
Hardware
Input Module
CPU (Central Process Unit)
Program memory
Output module
Power Supply
Software
Application Software (Logic)
Basic Software
Communication Accessories
Communication Adapter
INPUT-OUTPUT
Input and output (IO) modules connect the PLC to
sensors and actuators
Provide isolation for the low-voltage low-current
signals
Wide range of IO modules available including
Digital (logical) IO modules and Analogue (continuous) IO modules
Analogue input cards convert continuous signals via an AD converter into discrete
values for the PLC
Analogue output cards convert digital values in then PLC to continuous signals via a
DA converter
Resolution can be important in choosing an applicable card
Module receptacle for battery EEPROM
CPU statu
s LEDrsquo
sCommunicatio
ns interfa
ce
Status LEDrsquos of
the inputs
and outputs
Fixing holes for wall
mounting
Locking clip for DIN rail mounting
Analog potentiometer
Removable
connection
terminals(on 224 226)
Example for a temperature input of 0 to 100 degrees C
For 8 bit resolution the value in the PLC is 0 to 255
For 12 bit resolution the value in the PLC is 0 to 4095
For 16 bit resolution the value in the PLC is 0 to 32768
SPECIAL MODULES
RF ID
Modem modules
Load Cell
Stepper Modules
Temperature Sensor
High Speed Counters
Position Control Cards
Field Bus Cards
o Device Net Profibus Ethernet etc
ELEMENTS OF INPUTS
Digital Inputs
push button
limit switches
Sensors
o Proximity Sensors
o Photo Sensors
Micro Switches
Toggle Switches
Analog Inputs
Pressure Transmitters
Flow Transmitter
Level Transmitter
Thermo Couples
Load Cell
ELEMENTS OF OUTPUTS
Digital Outputs
Relays
Contactors
Indication Lamps
Valves
Analog Outputs
Flow Control Valves
Pressure Control Valves
Drive Inputs
BASIC ELEMENTS OF A PROGRAM
A program block is composed of executable code and comments The executable codes consist of a main program and any subroutines or interrupt routines The code is compiled and downloaded to the S7-200 the program comments are not You can use the organizational elements (main program subroutines and interrupt routines) to structure your control program
Main ProgramThe main body of the program contains the instructions that control your application The S7-200 executes these instructions sequentially once per scan cycle The main program is also referred to as OB1
SubroutinesThese optional elements of your program are executed only when called by the main program by an interrupt routine or by another subroutine Subroutines are useful in cases where you want to execute a function repeatedly Rather than rewriting the logic for each place in the main program where you want the function to occur you can write the logic once in a subroutine and call the subroutine as many times as needed during the main program Subroutines provide several benefits
1048600 Using subroutines reduces the overall size of your program 1048600 Using subroutines decreases your scan time because you have moved the code out of the main program The S7-200 evaluates the code in the main program every scan cycle whether the code is executed or not but the S7-200 evaluates the code in the subroutine only when you call the subroutine and does not evaluate the code during the scans in which the subroutine is not called 1048600 Using subroutines creates code that is portable You can isolate the code for a function in a subroutine and then copy that subroutine into other programs with Interrupt RoutinesThese optional elements of your program react to specific interrupt events You design an interrupt routine to handle a pre-defined interrupt event Whenever the specified event occurs the S7-200 executes the interrupt routineThe interrupt routines are not called by your main program You associate an interrupt routine with an interrupt event and the S7-200 executes the instructions in the interrupt routine only on each occurrence of the interrupt event Other Elements of the ProgramOther blocks contain information for the S7-200 You can choose to download these blocks when you download your programSystem BlockThe system block allows you to configure different hardware options for the S7-200Data BlockThe data block stores the values for different variables (V memory) used by your program You can use the data block to enter initial values for the data
PROGRAMMING LANGUAGES IN PLC
IL (Instruction List) ndash mnemonic programming
LD (Ladder Diagram) ndash Relay logic
ST (Structured Text) ndash A C like programming language
FDB (Functional Block Diagram) ndash Graphical dataflow programming language
SFC (Sequential Flow Chart) ndash Graphical method for structured programs
Basic PLC Memory
Memory on a PLC is separated into 3 main areas
LOAD Memory
Can be RAM (dynamic) or EEPROM (retentive)
Used to store user programs
WORK Memory
Memory is RAM
When PLC starts Program is copied from LOAD memory to
WORK memory The program is then executed from Work
memory
SYSTEM Memory
Memory is RAM
Is used by micro-controller to implement counters timers interrupt
stacks etc
Contains a bit for each D I0
Contains ldquoMarker Memoryrdquo Marker memory is a free area of RAM
that can be used by the programmer
Contains ldquoProcess Input and Output Imagesrdquo Periodically the PLC
will store the states of the inputs to the Process Input Image and
Process Output Image to the output
SELECTION OF A PLC
Selection of PLC Based on
No of Inputs amp Outputs
Input Voltage
Memory
Scan Time
Special IO modules
Expansion Capabilities
Stand alone or Networked
Communication Capabilities
HOW PLC WORKS
Step 1-CHECKING INPUT STATUS
o PLC Scans each input
o Records the data in work memory
Step 2-EXECUTE PROGRAM
o PLC goes through the program logic step by step
o PLC executes the program depending on input status
o Write the output image in work memory
Step 3-UPDATE OUTPUT STATUS
o Changes the statues of the output onoff
o Again starts the cycle from step one
FEATURES OF S7-200
Allows Your Program to Immediately Read or Write the IO
Allows Your Program to Interrupt the Scan Cycle
Allows You to Allocate Processing Time for Communications
Tasks
Allows You to Set the States of Digital Outputs for Stop
CHECK
INPUT STATUS
EXECUTE
PROGRAM
UPDATE
OUTPUT STATUS
Mode
Allows You to Define Memory to Be Retained on Loss of Power
Allows You to Filter the Digital Inputs
Allows You to Filter the Analog Inputs
Allows You to Catch Pulses of Short Duration
Provides Password Protection
Provides Analog Adjustment Potentiometers
Provides High-speed IO
TECHNICAL FEATURES OF S7-200
Several models of CPUrsquos
o CPU 221 6in4out 2Kw program
o CPU 222 8in6out 2Kw program
o CPU 224 14in10out 4Kw program
o CPU 226 24in16out 4Kw program
Up to 256 digital input-outputs
Up to 32 analog channels
256 timers 256 counters
Built-in EEPROM memory
Real-time clockcalendar
Built-in communications
Password protection
Memory module
Removable input-output connectors
Wide range of expansion modules
o 8 pt input and output
o 4488 amp1616 inout combination
o 4 channel analog in 2 channel analog out
o 4 ch1ch analog inout combination
o 2 channel RTD in
o 4 channel thermocouple in
o PROFIBUS-DP Slave
o AS Interface master
SELECTING THE OPERATING MODE FOR THE S7- 200 CPU
The S7-200 has two modes of operation STOP mode and RUN mode The status LED on the front of the CPU indicates the current mode of operation In STOP mode the S7-200 is not executing the program and you can download a program or the CPU configuration In RUN mode the S7-200 is running the program
1048600 The S7-200 provides a mode switch for changing the mode of operation You can use the mode switch (located under the front access door of the S7-200) to manually select the operating mode setting the mode switch to STOP mode stops the execution of the program setting the mode switch to RUN mode starts the execution of the program and setting the mode switch to TERM (terminal) mode does not change the operating mode
If a power cycle occurs when the mode switch is set to either STOP or TERM the
S7-200 goes automatically to STOP mode when power is restored If a power cycle occurs when the mode switch is set to RUN the S7-200 goes to RUN mode when power is restored
1048600 STEP 7--MicroWIN allows you to change the operating mode of the online S7-200 To enable the software to change the operating mode you must manually set the mode switch on the S7-200 to either TERM or RUN You can use the PLC gt STOP or PLC gt RUN menu commands or the associated buttons on the toolbar to change the operating mode
1048600 You can insert the STOP instruction in your program to change the S7-200 to STOP mode This allows you to halt the execution of your program based on the program logic
ERRORS IN S7-200
Non-Fatal Errors
Non-fatal errors are those indicating problems with the construction of the user program with the execution of an instruction in the user program and with expansion IO modules You can use STEP 7--MicroWIN to view the error codes that were generated by the non-fatal error There are three basic categories of non-fatal errors
Program-compile errorsThe S7-200 compiles the program as it downloads If the S7-200 detects that the program violates a compilation rule the download is aborted and an error code is generated (A program that was already downloaded to the S7-200 would still exist in the EEPROM and would not be lost) After you correct your program you can download it again
IO errorsAt startup the S7-200 reads the IO configuration from each module During normal operation the S7-200 periodically checks the status of each module and compares it against the configuration obtained during startup If the S7-200 detects a difference the S7-200 sets the configuration error bit in the module error register The S7-200 does not read input data from or write output data to that module until the module configuration again matches the one obtained at startupThe module status information is stored in special memory (SM) bits Your program can monitor and evaluate these bits Refer to Appendix D for more information about the SM bits used for reporting IO errors SM50 is the global IO error bit and remains set while an error condition exists on an expansion module
Program execution errorsYour program can create error conditions while being executed These errors can result from improper use of an instruction or from the processing of invalid data by an instruction For example an indirect-address pointer that was valid when the program compiled could be modified during the execution of the program to point to an out-of-range address This is an example of a run-time programming problem SM43 is setupon the occurrence of a run-time programming problem and remains set while the S7-200 is in RUN mode Program execution error information is stored in special memory (SM) bits Your program can monitor and evaluate these bits The S7-200 does not change to STOP mode when it detects a non-fatal error It only logs the event in SM memory and continues with the execution of your program However you can design your program to force the S7-200 to STOP mode when a non-fatal error is detected
Fatal Errors
Fatal errors cause the S7-200 to stop the execution of your program Depending upon the severity of the fatal error it can render the S7-200 incapable of performing any or all functions The objective for handling fatal errors is to bring the S7-200 to a safe state from which the S7-200 can respond to interrogations about the existing error conditions When a fatal error is detected the S7-200 changes to STOP mode turns on the System Fault LED and the STOP LED overrides the output table and turns off the outputsThe S7-200 remains in this condition until the fatal error condition is corrected
Once you have made the changes to correct the fatal error condition use one of the following methods to restart the S7-200 1048600 Turn the power off and then on 1048600 Change the mode switch from RUN or TERM to STOP 1048600 Select the PLC gt Power-Up Reset menu command from STEP 7--MicroWIN
to restart the S7-200This forces the S7-200 to restart and clear any fatal errors
Restarting the S7-200 clears the fatal error condition and performs power-up diagnostic testing to verify that the fatal error has been corrected If another fatal error condition is found the S7-200 again sets the fault LED indicating that an error still exists Otherwise the S7-200 begins normal operation
Some error conditions can render the S7-200 incapable of communication In these cases you cannot view the error code from the S7-200 These types of errors indicate hardware failures that require the S7-200 to be repaired they cannot be fixed by changes to the program or clearing the memory of the S7-200
APPLICATIONS OF S7-200
Conveyer Systems
Elevators
Test Stations
Placement Systems
Woodworking Machinery
Packaging Equipment
Car Wash Automation
Remote Monitoring And Controlling For Water Wastewater
FEATURES OF LADDER DIAGRAMS
The LAD editor displays the program as a graphical representation similar to electrical wiring diagrams
Ladder programs allow the program to emulate the flow of electric current from a power source through a series of logical input conditions that in turn enable logical output conditions
A LAD program includes a left power rail that is energized Contacts that are closed allow energy to flow through them to the next element and contacts that are open block that energy flow
The logic is separated into networks The program is executed one network at a time from left to right and then top to bottom as dictated by the program Figure shows an example of a LAD program
The various instructions are represented by graphic symbols and include three basic forms
Contacts represent logic input conditions such as switches buttons or internal conditions
Coils usually represent logic output results such as lamps motor starters interposing relays or internal output conditions
Boxes represent additional instructions such as timers counters or math instructions Figure Sample LAD Program
Consider these main points when you select the LAD editor 1048600 Ladder logic is easy for beginning programmers to use 1048600 Graphical representation is easy to understand and is popular around the world 1048600 The LAD editor can be used with both the SIMATIC and IEC 1131--3 Instruction sets
1048600 You can always use the STL editor to display a program created with
the SIMATIC LAD editor
COMPONENTS LIST
Cardboard of 4050 sqcm
PLC S7-200
Sensors
LEDS
Buzzers
Motor
Contactors
Power supply
12v DC battery
Connecting wires
PPI Cable
SENSORS
A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact A proximity sensor often emits an electromagnetic or electrostatic field or a beam of electromagnetic radiation (infrared for instance) and looks for changes in the field or return signal The object being sensed is often referred to as the proximity sensors target Different
proximity sensor targets demand different sensors For example a capacitive or photoelectric sensor might be suitable for a plastic target an inductive proximity sensor requires a metal target
The maximum distance that this sensor can detect is defined nominal range Some sensors have adjustments of the nominal range or means to report a graduated detection distance
Proximity sensors can have a high reliability and long functional life because of the absence of mechanical parts and lack of physical contact between sensor and the sensed object
IEC 60947-5-2 defines the technical details of proximity sensors
A proximity sensor adjusted to a very short range is often used as a touch switch
Applications
Car bumpers that sense distance to nearby cars for parking
Ground proximity warning system for aviation safety Vibration Position measurements of rotating shafts in
machinery Sheet break sensing in paper machine Anti-aircraft artillery
LEDS
Example Circuit symbol
FunctionLEDs emit light when an electric current passes through them
Testing an LED
Never connect an LED directly to a battery or power supply
LEDs must have a resistor in series to limit the current to a safe value for quick testing purposes a 1k resistor is suitable for most LEDs if your supply voltage is 12V or less Remember to connect the LED the correct way round
Sizes Shapes and Viewing angles of LEDs
LEDs are available in a wide variety of sizes and shapes The standard LED has a round cross-section of 5mm diameter and this is probably the best type for general use but 3mm round LEDs are also popular
Round cross-section LEDs are frequently used and they are very easy to install on boxes by drilling a hole of the LED diameter adding a spot of glue will help to hold the LED if necessary LED clips are also available to secure LEDs in holes Other cross-section shapes include square rectangular and triangular
As well as a variety of colours sizes and shapes LEDs also vary in their viewing angle This tells you how much the beam of light spreads out Standard LEDs have a viewing angle of 60deg but others have a narrow beam of 30deg or less
Calculating an LED resistor value
An LED must have a resistor connected in series to limit the current through the LED otherwise it will burn out almost instantly
The resistor value R is given by
R = (VS - VL) I
VS = supply voltage VL = LED voltage (usually 2V but 4V for blue and white LEDs) I = LED current (eg 20mA) this must be less than the maximum permitted
If the calculated value is not available choose the nearest standard resistor value which is greater so that the current will be a little less than you chose In fact you may wish to choose a greater resistor value to reduce the current (to increase battery life for example) but this will make the LED less bright
Working out the LED resistor formula using Ohms law
Ohms law says that the resistance of the resistor R = VI where V = voltage across the resistor (= VS - VL in this case) I = the current through the resistor
So R = (VS - VL) I
BUZZERS
A buzzer or beeper (BUZZERS) is a signalling device usually electronic typically used in automobiles household appliances such as a microwave oven or game shows It most commonly consists of a number of switches or sensors connected to a control unit that determines if and which button was pushed or a preset time has lapsed and usually illuminates a light on the appropriate button or control panel and sounds a warning in the form of a continuous or intermittent buzzing
or beeping sound Initially this device was based on an electromechanical system which was identical to an electric bell without the metal gong (which makes the ringing noise) Often these units were anchored to a wall or ceiling and used the ceiling or wall as a sounding board Another implementation with some AC-connected devices was to implement a circuit to make the AC current into a noise loud enough to drive a loudspeaker and hook this circuit up to a cheap 8-ohm speaker Nowadays it is more popular to use a ceramic-based piezoelectric sounder which makes a high-pitched tone Usually these were hooked up to driver circuits which varied the pitch of the sound or pulsed the sound on and off
The word buzzer comes from the rasping noise that buzzers made when they were electromechanical devices operated from stepped-down AC line voltage at 50 or 60 cycles Other sounds commonly used to indicate that a button has been pressed are a ring or a beep
MOTORS
An electric motor is a device using electrical energy to produce mechanical energy nearly always by the interaction of magnetic fields and current-carrying conductors The reverse process that of using mechanical energy to produce electrical energy is accomplished by a generator or dynamo Traction motors used on vehicles often perform both tasks
Electric motors are found in myriad uses such as industrial fans blowers and pumps machine tools household appliances power tools and computer disk drives among
many other applications Electric motors may be operated by direct current from a battery in a portable device or motor vehicle or from alternating current from a central electrical distribution grid The smallest motors may be found in electric wristwatches Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses The very largest electric motors are used for propulsion of large ships and for such purposes as pipeline compressors with ratings in the thousands of kilowatts Electric motors may be classified by the source of electric power by their internal construction and by application
The physical principle of production of mechanical force by the interaction of an electric current and a magnetic field was known as early as 1821 Electric motors of increasing efficiency were constructed throughout the 19th century but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks
CONNECTORS
A DC connector is an electrical connector for
supplying direct current (DC) power DC connectors
are poorly standardized compared to domestic AC
power plugs and sockets DC plug is a common name
used for one common type of cylindrical two-conductor
plug available in a range of sizes and used to power
small pieces of electronic equipment It is also used to
describe some older multi-pin plugs
Several competing standards exist for DC plugs and in some cases incompatible plugs
will fit together to avoid damaging equipment these conditions must be true
Voltage must match
Polarity is correct
Current ratings are sufficient
Power supply filtering and stability is adequate
for the equipment being powered
Non-matching connectors are forced together
12V DC BATTERY
Features
Less than a 12 volt self discharge per 6 months 4 ea 12Vdc outputs 20 AmpHours Built-charger Digital Voltmeter
Description
This unit supplies a full 12Vdc at 20 AmpHours Designed for the officer that needs a power source that can be charged from 115Ac source or on the way to a incident from the car
The battery source has a very low self discharge rate which makes it perfect for law enforcement use The battery can set on the shelf for more than 6 months without recharging
Everyone knows when you grab a battery operated device the internal battery always requires several hours of charging before using The new voltage indicator reads out voltage to one hundredth of a volt for accurate operation The four outputs are 21mm plug Quick terminals and Cigarette lighter jack amp PT02 (Mil Spec) This model also allows powering
12Vdc sources while plugged in to 115Vac ldquoIts a UPSrdquo
SPECIFICATIONS OF COMPONENTS USED
PLC S7-200
INPUT POWER 230V AC 50 Hz
INPUTS 24 DC INPUTS
OUTPUTS 16 DC OUTPUTS
PROGRAM MEMORY 24
DATA MEMORY 10KB
EXPANSION MODULES 7
COMMUNICATION PORTS 2 RS 485
DIGITAL IO IMAGE SIZE 256(128 in 128 out)
EXECUTION SPEED 022microsecondsinstruction
SENSORS
SENSING RANGE 3mm
HOUSING MATERIAL Brass Nickel Plated
OPERATING VOLTAGE 10-30V
OPERATING CURRENT lt200mA
CONNECTION TYPE Cable
LEDS
DIAMETER 5mm
MAXIMUM VOLTAGE 1V
MAXIMUM CURRENT 10mA
INTENSITY
BUZZERS
OPERATING VOLTAGE30Vp-p
RATED FREQUENCY2000Hz 500Hz
OPERATING TEMP RANGE -20 to 60 degree
SOUND OUTPUT70 dB min10 cm
MOTOR
TOTAL LENGTH 46mm MOTOR DIAMETER 36mm MOTOR LENGTH 25mm DC SUPPLY 4 to 12V RPM 100 BRUSH TYPE Precious metal GEAR HEAD DIAMETER 37mm GEAR HEAD LENGTH 21mm OUTPUT SHAFT Centered SHAFT DIAMETER 4mm and 6mm
SHAFT LENGTH 22mm
- Block diagram of plc
- Applications
-
- Function
- Testing an LED
- Sizes Shapes and Viewing angles of LEDs
- Calculating an LED resistor value
-
- Working out the LED resistor formula using Ohms law
-
23 PROGRAMMING
Early PLCs up to the mid-1980s were programmed using proprietary programming panels or special-purpose programming terminals which often had dedicated function keys representing the various logical elements of PLC programs Programs were stored on cassette tape cartridges Facilities for printing and documentation were very minimal due to lack of memory capacity The very oldest PLCs used non-volatile magnetic core memory
24 FUNCTIONALITY
The functionality of the PLC has evolved over the years to include sequential relay control motion control process control distributed control systems and networking The data handling storage processing power and communication capabilities of some modern PLCs are approximately equivalent to desktop computers PLC-like programming combined with remote IO hardware allow a general-purpose desktop computer to overlap some PLCs in certain applications
PLC ARCHITECTURE
CPU
Power Supply
Memory
Input Blocks
Output Blocks
Communications
Expansion Connections
BLOCK DIAGRAM OF PLC
SENSORS
PLC COMPARED WITH OTHER CONTROL SYSTEMS
PLCs are well-adapted to a range of automation tasks These are typically industrial processes in manufacturing where the cost of developing and maintaining the automation system is high relative to the total cost of the automation and where changes to the system would be expected during its operational life PLCs contain input and output devices compatible with industrial pilot devices and controls little electrical design is required and the design problem centers on expressing the desired sequence of operations in ladder logic (or function chart) notation PLC applications are typically highly customized systems so the cost of a packaged PLC is low compared to the cost of a specific custom-built controller design On the other hand in the case of mass-produced goods customized control systems are economic due to the lower cost of the components which can be optimally chosen instead of a generic solution and where the non-recurring engineering charges are spread over thousands or millions of units
For high volume or very simple fixed automation tasks different techniques are used A microcontroller-based design would be appropriate where hundreds or thousands of units will be produced and so the development cost (design of power supplies and inputoutput hardware) can be spread over many sales and where the end-user would not need to alter the control Automotive applications are an example millions of units are built each year and very few end-users alter the programming of these controllers
Power supply
Input
Module
Memory
Processor
Output
Module
However some specialty vehicles such as transit busses economically use PLCs instead of custom-designed controls because the volumes are low and the development cost would be uneconomic
Very complex process control such as used in the chemical industry may require algorithms and performance beyond the capability of even high-performance PLCs Very high-speed or precision controls may also require customized solutions for example aircraft flight controls
Programmable controllers are widely used in motion control positioning control and torque control Some manufacturers produce motion control units to be integrated with PLC so that G-code (involving a CNC machine) can be used to instruct machine movements
PLCs may include logic for single-variable feedback analog control loop a proportional integral derivative or PID controller A PID loop could be used to control the temperature of a manufacturing process for example Historically PLCs were usually configured with only a few analog control loops where processes required hundreds or thousands of loops a distributed control system (DCS) would instead be used As PLCs have become more powerful the boundary between DCS and PLC applications has become less distinct
PLCs have similar functionality as Remote Terminal Units An RTU however usually does not support control algorithms or control loops As hardware rapidly becomes more powerful and cheaper RTUs PLCs and DCSs are increasingly beginning to overlap in responsibilities The industry has standardized on the IEC 61131-3 functional block language for creating programs to run on RTUs and PLCs although nearly all vendors also offer proprietary alternatives and associated development environments
DISADVANTAGES OF lsquoHARD WIRED LOGIC CONTROLrsquo
Bulky panels
Complex wiring
Longer project time
Difficult maintenance and troubleshooting
ADVANTAGES OF lsquoPLCSrsquo
Reduced space
Ease of maintenance
Economical
Greater life amp reliability
Tremendous flexibility
Shorter project time
Easier storage archiving and documentation
WHAT CONSTITUTES A PLC
The PLC is programmed interface between the Input field elements amp output field
elements
PLC consist of
Hardware
Input Module
CPU (Central Process Unit)
Program memory
Output module
Power Supply
Software
Application Software (Logic)
Basic Software
Communication Accessories
Communication Adapter
INPUT-OUTPUT
Input and output (IO) modules connect the PLC to
sensors and actuators
Provide isolation for the low-voltage low-current
signals
Wide range of IO modules available including
Digital (logical) IO modules and Analogue (continuous) IO modules
Analogue input cards convert continuous signals via an AD converter into discrete
values for the PLC
Analogue output cards convert digital values in then PLC to continuous signals via a
DA converter
Resolution can be important in choosing an applicable card
Module receptacle for battery EEPROM
CPU statu
s LEDrsquo
sCommunicatio
ns interfa
ce
Status LEDrsquos of
the inputs
and outputs
Fixing holes for wall
mounting
Locking clip for DIN rail mounting
Analog potentiometer
Removable
connection
terminals(on 224 226)
Example for a temperature input of 0 to 100 degrees C
For 8 bit resolution the value in the PLC is 0 to 255
For 12 bit resolution the value in the PLC is 0 to 4095
For 16 bit resolution the value in the PLC is 0 to 32768
SPECIAL MODULES
RF ID
Modem modules
Load Cell
Stepper Modules
Temperature Sensor
High Speed Counters
Position Control Cards
Field Bus Cards
o Device Net Profibus Ethernet etc
ELEMENTS OF INPUTS
Digital Inputs
push button
limit switches
Sensors
o Proximity Sensors
o Photo Sensors
Micro Switches
Toggle Switches
Analog Inputs
Pressure Transmitters
Flow Transmitter
Level Transmitter
Thermo Couples
Load Cell
ELEMENTS OF OUTPUTS
Digital Outputs
Relays
Contactors
Indication Lamps
Valves
Analog Outputs
Flow Control Valves
Pressure Control Valves
Drive Inputs
BASIC ELEMENTS OF A PROGRAM
A program block is composed of executable code and comments The executable codes consist of a main program and any subroutines or interrupt routines The code is compiled and downloaded to the S7-200 the program comments are not You can use the organizational elements (main program subroutines and interrupt routines) to structure your control program
Main ProgramThe main body of the program contains the instructions that control your application The S7-200 executes these instructions sequentially once per scan cycle The main program is also referred to as OB1
SubroutinesThese optional elements of your program are executed only when called by the main program by an interrupt routine or by another subroutine Subroutines are useful in cases where you want to execute a function repeatedly Rather than rewriting the logic for each place in the main program where you want the function to occur you can write the logic once in a subroutine and call the subroutine as many times as needed during the main program Subroutines provide several benefits
1048600 Using subroutines reduces the overall size of your program 1048600 Using subroutines decreases your scan time because you have moved the code out of the main program The S7-200 evaluates the code in the main program every scan cycle whether the code is executed or not but the S7-200 evaluates the code in the subroutine only when you call the subroutine and does not evaluate the code during the scans in which the subroutine is not called 1048600 Using subroutines creates code that is portable You can isolate the code for a function in a subroutine and then copy that subroutine into other programs with Interrupt RoutinesThese optional elements of your program react to specific interrupt events You design an interrupt routine to handle a pre-defined interrupt event Whenever the specified event occurs the S7-200 executes the interrupt routineThe interrupt routines are not called by your main program You associate an interrupt routine with an interrupt event and the S7-200 executes the instructions in the interrupt routine only on each occurrence of the interrupt event Other Elements of the ProgramOther blocks contain information for the S7-200 You can choose to download these blocks when you download your programSystem BlockThe system block allows you to configure different hardware options for the S7-200Data BlockThe data block stores the values for different variables (V memory) used by your program You can use the data block to enter initial values for the data
PROGRAMMING LANGUAGES IN PLC
IL (Instruction List) ndash mnemonic programming
LD (Ladder Diagram) ndash Relay logic
ST (Structured Text) ndash A C like programming language
FDB (Functional Block Diagram) ndash Graphical dataflow programming language
SFC (Sequential Flow Chart) ndash Graphical method for structured programs
Basic PLC Memory
Memory on a PLC is separated into 3 main areas
LOAD Memory
Can be RAM (dynamic) or EEPROM (retentive)
Used to store user programs
WORK Memory
Memory is RAM
When PLC starts Program is copied from LOAD memory to
WORK memory The program is then executed from Work
memory
SYSTEM Memory
Memory is RAM
Is used by micro-controller to implement counters timers interrupt
stacks etc
Contains a bit for each D I0
Contains ldquoMarker Memoryrdquo Marker memory is a free area of RAM
that can be used by the programmer
Contains ldquoProcess Input and Output Imagesrdquo Periodically the PLC
will store the states of the inputs to the Process Input Image and
Process Output Image to the output
SELECTION OF A PLC
Selection of PLC Based on
No of Inputs amp Outputs
Input Voltage
Memory
Scan Time
Special IO modules
Expansion Capabilities
Stand alone or Networked
Communication Capabilities
HOW PLC WORKS
Step 1-CHECKING INPUT STATUS
o PLC Scans each input
o Records the data in work memory
Step 2-EXECUTE PROGRAM
o PLC goes through the program logic step by step
o PLC executes the program depending on input status
o Write the output image in work memory
Step 3-UPDATE OUTPUT STATUS
o Changes the statues of the output onoff
o Again starts the cycle from step one
FEATURES OF S7-200
Allows Your Program to Immediately Read or Write the IO
Allows Your Program to Interrupt the Scan Cycle
Allows You to Allocate Processing Time for Communications
Tasks
Allows You to Set the States of Digital Outputs for Stop
CHECK
INPUT STATUS
EXECUTE
PROGRAM
UPDATE
OUTPUT STATUS
Mode
Allows You to Define Memory to Be Retained on Loss of Power
Allows You to Filter the Digital Inputs
Allows You to Filter the Analog Inputs
Allows You to Catch Pulses of Short Duration
Provides Password Protection
Provides Analog Adjustment Potentiometers
Provides High-speed IO
TECHNICAL FEATURES OF S7-200
Several models of CPUrsquos
o CPU 221 6in4out 2Kw program
o CPU 222 8in6out 2Kw program
o CPU 224 14in10out 4Kw program
o CPU 226 24in16out 4Kw program
Up to 256 digital input-outputs
Up to 32 analog channels
256 timers 256 counters
Built-in EEPROM memory
Real-time clockcalendar
Built-in communications
Password protection
Memory module
Removable input-output connectors
Wide range of expansion modules
o 8 pt input and output
o 4488 amp1616 inout combination
o 4 channel analog in 2 channel analog out
o 4 ch1ch analog inout combination
o 2 channel RTD in
o 4 channel thermocouple in
o PROFIBUS-DP Slave
o AS Interface master
SELECTING THE OPERATING MODE FOR THE S7- 200 CPU
The S7-200 has two modes of operation STOP mode and RUN mode The status LED on the front of the CPU indicates the current mode of operation In STOP mode the S7-200 is not executing the program and you can download a program or the CPU configuration In RUN mode the S7-200 is running the program
1048600 The S7-200 provides a mode switch for changing the mode of operation You can use the mode switch (located under the front access door of the S7-200) to manually select the operating mode setting the mode switch to STOP mode stops the execution of the program setting the mode switch to RUN mode starts the execution of the program and setting the mode switch to TERM (terminal) mode does not change the operating mode
If a power cycle occurs when the mode switch is set to either STOP or TERM the
S7-200 goes automatically to STOP mode when power is restored If a power cycle occurs when the mode switch is set to RUN the S7-200 goes to RUN mode when power is restored
1048600 STEP 7--MicroWIN allows you to change the operating mode of the online S7-200 To enable the software to change the operating mode you must manually set the mode switch on the S7-200 to either TERM or RUN You can use the PLC gt STOP or PLC gt RUN menu commands or the associated buttons on the toolbar to change the operating mode
1048600 You can insert the STOP instruction in your program to change the S7-200 to STOP mode This allows you to halt the execution of your program based on the program logic
ERRORS IN S7-200
Non-Fatal Errors
Non-fatal errors are those indicating problems with the construction of the user program with the execution of an instruction in the user program and with expansion IO modules You can use STEP 7--MicroWIN to view the error codes that were generated by the non-fatal error There are three basic categories of non-fatal errors
Program-compile errorsThe S7-200 compiles the program as it downloads If the S7-200 detects that the program violates a compilation rule the download is aborted and an error code is generated (A program that was already downloaded to the S7-200 would still exist in the EEPROM and would not be lost) After you correct your program you can download it again
IO errorsAt startup the S7-200 reads the IO configuration from each module During normal operation the S7-200 periodically checks the status of each module and compares it against the configuration obtained during startup If the S7-200 detects a difference the S7-200 sets the configuration error bit in the module error register The S7-200 does not read input data from or write output data to that module until the module configuration again matches the one obtained at startupThe module status information is stored in special memory (SM) bits Your program can monitor and evaluate these bits Refer to Appendix D for more information about the SM bits used for reporting IO errors SM50 is the global IO error bit and remains set while an error condition exists on an expansion module
Program execution errorsYour program can create error conditions while being executed These errors can result from improper use of an instruction or from the processing of invalid data by an instruction For example an indirect-address pointer that was valid when the program compiled could be modified during the execution of the program to point to an out-of-range address This is an example of a run-time programming problem SM43 is setupon the occurrence of a run-time programming problem and remains set while the S7-200 is in RUN mode Program execution error information is stored in special memory (SM) bits Your program can monitor and evaluate these bits The S7-200 does not change to STOP mode when it detects a non-fatal error It only logs the event in SM memory and continues with the execution of your program However you can design your program to force the S7-200 to STOP mode when a non-fatal error is detected
Fatal Errors
Fatal errors cause the S7-200 to stop the execution of your program Depending upon the severity of the fatal error it can render the S7-200 incapable of performing any or all functions The objective for handling fatal errors is to bring the S7-200 to a safe state from which the S7-200 can respond to interrogations about the existing error conditions When a fatal error is detected the S7-200 changes to STOP mode turns on the System Fault LED and the STOP LED overrides the output table and turns off the outputsThe S7-200 remains in this condition until the fatal error condition is corrected
Once you have made the changes to correct the fatal error condition use one of the following methods to restart the S7-200 1048600 Turn the power off and then on 1048600 Change the mode switch from RUN or TERM to STOP 1048600 Select the PLC gt Power-Up Reset menu command from STEP 7--MicroWIN
to restart the S7-200This forces the S7-200 to restart and clear any fatal errors
Restarting the S7-200 clears the fatal error condition and performs power-up diagnostic testing to verify that the fatal error has been corrected If another fatal error condition is found the S7-200 again sets the fault LED indicating that an error still exists Otherwise the S7-200 begins normal operation
Some error conditions can render the S7-200 incapable of communication In these cases you cannot view the error code from the S7-200 These types of errors indicate hardware failures that require the S7-200 to be repaired they cannot be fixed by changes to the program or clearing the memory of the S7-200
APPLICATIONS OF S7-200
Conveyer Systems
Elevators
Test Stations
Placement Systems
Woodworking Machinery
Packaging Equipment
Car Wash Automation
Remote Monitoring And Controlling For Water Wastewater
FEATURES OF LADDER DIAGRAMS
The LAD editor displays the program as a graphical representation similar to electrical wiring diagrams
Ladder programs allow the program to emulate the flow of electric current from a power source through a series of logical input conditions that in turn enable logical output conditions
A LAD program includes a left power rail that is energized Contacts that are closed allow energy to flow through them to the next element and contacts that are open block that energy flow
The logic is separated into networks The program is executed one network at a time from left to right and then top to bottom as dictated by the program Figure shows an example of a LAD program
The various instructions are represented by graphic symbols and include three basic forms
Contacts represent logic input conditions such as switches buttons or internal conditions
Coils usually represent logic output results such as lamps motor starters interposing relays or internal output conditions
Boxes represent additional instructions such as timers counters or math instructions Figure Sample LAD Program
Consider these main points when you select the LAD editor 1048600 Ladder logic is easy for beginning programmers to use 1048600 Graphical representation is easy to understand and is popular around the world 1048600 The LAD editor can be used with both the SIMATIC and IEC 1131--3 Instruction sets
1048600 You can always use the STL editor to display a program created with
the SIMATIC LAD editor
COMPONENTS LIST
Cardboard of 4050 sqcm
PLC S7-200
Sensors
LEDS
Buzzers
Motor
Contactors
Power supply
12v DC battery
Connecting wires
PPI Cable
SENSORS
A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact A proximity sensor often emits an electromagnetic or electrostatic field or a beam of electromagnetic radiation (infrared for instance) and looks for changes in the field or return signal The object being sensed is often referred to as the proximity sensors target Different
proximity sensor targets demand different sensors For example a capacitive or photoelectric sensor might be suitable for a plastic target an inductive proximity sensor requires a metal target
The maximum distance that this sensor can detect is defined nominal range Some sensors have adjustments of the nominal range or means to report a graduated detection distance
Proximity sensors can have a high reliability and long functional life because of the absence of mechanical parts and lack of physical contact between sensor and the sensed object
IEC 60947-5-2 defines the technical details of proximity sensors
A proximity sensor adjusted to a very short range is often used as a touch switch
Applications
Car bumpers that sense distance to nearby cars for parking
Ground proximity warning system for aviation safety Vibration Position measurements of rotating shafts in
machinery Sheet break sensing in paper machine Anti-aircraft artillery
LEDS
Example Circuit symbol
FunctionLEDs emit light when an electric current passes through them
Testing an LED
Never connect an LED directly to a battery or power supply
LEDs must have a resistor in series to limit the current to a safe value for quick testing purposes a 1k resistor is suitable for most LEDs if your supply voltage is 12V or less Remember to connect the LED the correct way round
Sizes Shapes and Viewing angles of LEDs
LEDs are available in a wide variety of sizes and shapes The standard LED has a round cross-section of 5mm diameter and this is probably the best type for general use but 3mm round LEDs are also popular
Round cross-section LEDs are frequently used and they are very easy to install on boxes by drilling a hole of the LED diameter adding a spot of glue will help to hold the LED if necessary LED clips are also available to secure LEDs in holes Other cross-section shapes include square rectangular and triangular
As well as a variety of colours sizes and shapes LEDs also vary in their viewing angle This tells you how much the beam of light spreads out Standard LEDs have a viewing angle of 60deg but others have a narrow beam of 30deg or less
Calculating an LED resistor value
An LED must have a resistor connected in series to limit the current through the LED otherwise it will burn out almost instantly
The resistor value R is given by
R = (VS - VL) I
VS = supply voltage VL = LED voltage (usually 2V but 4V for blue and white LEDs) I = LED current (eg 20mA) this must be less than the maximum permitted
If the calculated value is not available choose the nearest standard resistor value which is greater so that the current will be a little less than you chose In fact you may wish to choose a greater resistor value to reduce the current (to increase battery life for example) but this will make the LED less bright
Working out the LED resistor formula using Ohms law
Ohms law says that the resistance of the resistor R = VI where V = voltage across the resistor (= VS - VL in this case) I = the current through the resistor
So R = (VS - VL) I
BUZZERS
A buzzer or beeper (BUZZERS) is a signalling device usually electronic typically used in automobiles household appliances such as a microwave oven or game shows It most commonly consists of a number of switches or sensors connected to a control unit that determines if and which button was pushed or a preset time has lapsed and usually illuminates a light on the appropriate button or control panel and sounds a warning in the form of a continuous or intermittent buzzing
or beeping sound Initially this device was based on an electromechanical system which was identical to an electric bell without the metal gong (which makes the ringing noise) Often these units were anchored to a wall or ceiling and used the ceiling or wall as a sounding board Another implementation with some AC-connected devices was to implement a circuit to make the AC current into a noise loud enough to drive a loudspeaker and hook this circuit up to a cheap 8-ohm speaker Nowadays it is more popular to use a ceramic-based piezoelectric sounder which makes a high-pitched tone Usually these were hooked up to driver circuits which varied the pitch of the sound or pulsed the sound on and off
The word buzzer comes from the rasping noise that buzzers made when they were electromechanical devices operated from stepped-down AC line voltage at 50 or 60 cycles Other sounds commonly used to indicate that a button has been pressed are a ring or a beep
MOTORS
An electric motor is a device using electrical energy to produce mechanical energy nearly always by the interaction of magnetic fields and current-carrying conductors The reverse process that of using mechanical energy to produce electrical energy is accomplished by a generator or dynamo Traction motors used on vehicles often perform both tasks
Electric motors are found in myriad uses such as industrial fans blowers and pumps machine tools household appliances power tools and computer disk drives among
many other applications Electric motors may be operated by direct current from a battery in a portable device or motor vehicle or from alternating current from a central electrical distribution grid The smallest motors may be found in electric wristwatches Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses The very largest electric motors are used for propulsion of large ships and for such purposes as pipeline compressors with ratings in the thousands of kilowatts Electric motors may be classified by the source of electric power by their internal construction and by application
The physical principle of production of mechanical force by the interaction of an electric current and a magnetic field was known as early as 1821 Electric motors of increasing efficiency were constructed throughout the 19th century but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks
CONNECTORS
A DC connector is an electrical connector for
supplying direct current (DC) power DC connectors
are poorly standardized compared to domestic AC
power plugs and sockets DC plug is a common name
used for one common type of cylindrical two-conductor
plug available in a range of sizes and used to power
small pieces of electronic equipment It is also used to
describe some older multi-pin plugs
Several competing standards exist for DC plugs and in some cases incompatible plugs
will fit together to avoid damaging equipment these conditions must be true
Voltage must match
Polarity is correct
Current ratings are sufficient
Power supply filtering and stability is adequate
for the equipment being powered
Non-matching connectors are forced together
12V DC BATTERY
Features
Less than a 12 volt self discharge per 6 months 4 ea 12Vdc outputs 20 AmpHours Built-charger Digital Voltmeter
Description
This unit supplies a full 12Vdc at 20 AmpHours Designed for the officer that needs a power source that can be charged from 115Ac source or on the way to a incident from the car
The battery source has a very low self discharge rate which makes it perfect for law enforcement use The battery can set on the shelf for more than 6 months without recharging
Everyone knows when you grab a battery operated device the internal battery always requires several hours of charging before using The new voltage indicator reads out voltage to one hundredth of a volt for accurate operation The four outputs are 21mm plug Quick terminals and Cigarette lighter jack amp PT02 (Mil Spec) This model also allows powering
12Vdc sources while plugged in to 115Vac ldquoIts a UPSrdquo
SPECIFICATIONS OF COMPONENTS USED
PLC S7-200
INPUT POWER 230V AC 50 Hz
INPUTS 24 DC INPUTS
OUTPUTS 16 DC OUTPUTS
PROGRAM MEMORY 24
DATA MEMORY 10KB
EXPANSION MODULES 7
COMMUNICATION PORTS 2 RS 485
DIGITAL IO IMAGE SIZE 256(128 in 128 out)
EXECUTION SPEED 022microsecondsinstruction
SENSORS
SENSING RANGE 3mm
HOUSING MATERIAL Brass Nickel Plated
OPERATING VOLTAGE 10-30V
OPERATING CURRENT lt200mA
CONNECTION TYPE Cable
LEDS
DIAMETER 5mm
MAXIMUM VOLTAGE 1V
MAXIMUM CURRENT 10mA
INTENSITY
BUZZERS
OPERATING VOLTAGE30Vp-p
RATED FREQUENCY2000Hz 500Hz
OPERATING TEMP RANGE -20 to 60 degree
SOUND OUTPUT70 dB min10 cm
MOTOR
TOTAL LENGTH 46mm MOTOR DIAMETER 36mm MOTOR LENGTH 25mm DC SUPPLY 4 to 12V RPM 100 BRUSH TYPE Precious metal GEAR HEAD DIAMETER 37mm GEAR HEAD LENGTH 21mm OUTPUT SHAFT Centered SHAFT DIAMETER 4mm and 6mm
SHAFT LENGTH 22mm
- Block diagram of plc
- Applications
-
- Function
- Testing an LED
- Sizes Shapes and Viewing angles of LEDs
- Calculating an LED resistor value
-
- Working out the LED resistor formula using Ohms law
-
BLOCK DIAGRAM OF PLC
SENSORS
PLC COMPARED WITH OTHER CONTROL SYSTEMS
PLCs are well-adapted to a range of automation tasks These are typically industrial processes in manufacturing where the cost of developing and maintaining the automation system is high relative to the total cost of the automation and where changes to the system would be expected during its operational life PLCs contain input and output devices compatible with industrial pilot devices and controls little electrical design is required and the design problem centers on expressing the desired sequence of operations in ladder logic (or function chart) notation PLC applications are typically highly customized systems so the cost of a packaged PLC is low compared to the cost of a specific custom-built controller design On the other hand in the case of mass-produced goods customized control systems are economic due to the lower cost of the components which can be optimally chosen instead of a generic solution and where the non-recurring engineering charges are spread over thousands or millions of units
For high volume or very simple fixed automation tasks different techniques are used A microcontroller-based design would be appropriate where hundreds or thousands of units will be produced and so the development cost (design of power supplies and inputoutput hardware) can be spread over many sales and where the end-user would not need to alter the control Automotive applications are an example millions of units are built each year and very few end-users alter the programming of these controllers
Power supply
Input
Module
Memory
Processor
Output
Module
However some specialty vehicles such as transit busses economically use PLCs instead of custom-designed controls because the volumes are low and the development cost would be uneconomic
Very complex process control such as used in the chemical industry may require algorithms and performance beyond the capability of even high-performance PLCs Very high-speed or precision controls may also require customized solutions for example aircraft flight controls
Programmable controllers are widely used in motion control positioning control and torque control Some manufacturers produce motion control units to be integrated with PLC so that G-code (involving a CNC machine) can be used to instruct machine movements
PLCs may include logic for single-variable feedback analog control loop a proportional integral derivative or PID controller A PID loop could be used to control the temperature of a manufacturing process for example Historically PLCs were usually configured with only a few analog control loops where processes required hundreds or thousands of loops a distributed control system (DCS) would instead be used As PLCs have become more powerful the boundary between DCS and PLC applications has become less distinct
PLCs have similar functionality as Remote Terminal Units An RTU however usually does not support control algorithms or control loops As hardware rapidly becomes more powerful and cheaper RTUs PLCs and DCSs are increasingly beginning to overlap in responsibilities The industry has standardized on the IEC 61131-3 functional block language for creating programs to run on RTUs and PLCs although nearly all vendors also offer proprietary alternatives and associated development environments
DISADVANTAGES OF lsquoHARD WIRED LOGIC CONTROLrsquo
Bulky panels
Complex wiring
Longer project time
Difficult maintenance and troubleshooting
ADVANTAGES OF lsquoPLCSrsquo
Reduced space
Ease of maintenance
Economical
Greater life amp reliability
Tremendous flexibility
Shorter project time
Easier storage archiving and documentation
WHAT CONSTITUTES A PLC
The PLC is programmed interface between the Input field elements amp output field
elements
PLC consist of
Hardware
Input Module
CPU (Central Process Unit)
Program memory
Output module
Power Supply
Software
Application Software (Logic)
Basic Software
Communication Accessories
Communication Adapter
INPUT-OUTPUT
Input and output (IO) modules connect the PLC to
sensors and actuators
Provide isolation for the low-voltage low-current
signals
Wide range of IO modules available including
Digital (logical) IO modules and Analogue (continuous) IO modules
Analogue input cards convert continuous signals via an AD converter into discrete
values for the PLC
Analogue output cards convert digital values in then PLC to continuous signals via a
DA converter
Resolution can be important in choosing an applicable card
Module receptacle for battery EEPROM
CPU statu
s LEDrsquo
sCommunicatio
ns interfa
ce
Status LEDrsquos of
the inputs
and outputs
Fixing holes for wall
mounting
Locking clip for DIN rail mounting
Analog potentiometer
Removable
connection
terminals(on 224 226)
Example for a temperature input of 0 to 100 degrees C
For 8 bit resolution the value in the PLC is 0 to 255
For 12 bit resolution the value in the PLC is 0 to 4095
For 16 bit resolution the value in the PLC is 0 to 32768
SPECIAL MODULES
RF ID
Modem modules
Load Cell
Stepper Modules
Temperature Sensor
High Speed Counters
Position Control Cards
Field Bus Cards
o Device Net Profibus Ethernet etc
ELEMENTS OF INPUTS
Digital Inputs
push button
limit switches
Sensors
o Proximity Sensors
o Photo Sensors
Micro Switches
Toggle Switches
Analog Inputs
Pressure Transmitters
Flow Transmitter
Level Transmitter
Thermo Couples
Load Cell
ELEMENTS OF OUTPUTS
Digital Outputs
Relays
Contactors
Indication Lamps
Valves
Analog Outputs
Flow Control Valves
Pressure Control Valves
Drive Inputs
BASIC ELEMENTS OF A PROGRAM
A program block is composed of executable code and comments The executable codes consist of a main program and any subroutines or interrupt routines The code is compiled and downloaded to the S7-200 the program comments are not You can use the organizational elements (main program subroutines and interrupt routines) to structure your control program
Main ProgramThe main body of the program contains the instructions that control your application The S7-200 executes these instructions sequentially once per scan cycle The main program is also referred to as OB1
SubroutinesThese optional elements of your program are executed only when called by the main program by an interrupt routine or by another subroutine Subroutines are useful in cases where you want to execute a function repeatedly Rather than rewriting the logic for each place in the main program where you want the function to occur you can write the logic once in a subroutine and call the subroutine as many times as needed during the main program Subroutines provide several benefits
1048600 Using subroutines reduces the overall size of your program 1048600 Using subroutines decreases your scan time because you have moved the code out of the main program The S7-200 evaluates the code in the main program every scan cycle whether the code is executed or not but the S7-200 evaluates the code in the subroutine only when you call the subroutine and does not evaluate the code during the scans in which the subroutine is not called 1048600 Using subroutines creates code that is portable You can isolate the code for a function in a subroutine and then copy that subroutine into other programs with Interrupt RoutinesThese optional elements of your program react to specific interrupt events You design an interrupt routine to handle a pre-defined interrupt event Whenever the specified event occurs the S7-200 executes the interrupt routineThe interrupt routines are not called by your main program You associate an interrupt routine with an interrupt event and the S7-200 executes the instructions in the interrupt routine only on each occurrence of the interrupt event Other Elements of the ProgramOther blocks contain information for the S7-200 You can choose to download these blocks when you download your programSystem BlockThe system block allows you to configure different hardware options for the S7-200Data BlockThe data block stores the values for different variables (V memory) used by your program You can use the data block to enter initial values for the data
PROGRAMMING LANGUAGES IN PLC
IL (Instruction List) ndash mnemonic programming
LD (Ladder Diagram) ndash Relay logic
ST (Structured Text) ndash A C like programming language
FDB (Functional Block Diagram) ndash Graphical dataflow programming language
SFC (Sequential Flow Chart) ndash Graphical method for structured programs
Basic PLC Memory
Memory on a PLC is separated into 3 main areas
LOAD Memory
Can be RAM (dynamic) or EEPROM (retentive)
Used to store user programs
WORK Memory
Memory is RAM
When PLC starts Program is copied from LOAD memory to
WORK memory The program is then executed from Work
memory
SYSTEM Memory
Memory is RAM
Is used by micro-controller to implement counters timers interrupt
stacks etc
Contains a bit for each D I0
Contains ldquoMarker Memoryrdquo Marker memory is a free area of RAM
that can be used by the programmer
Contains ldquoProcess Input and Output Imagesrdquo Periodically the PLC
will store the states of the inputs to the Process Input Image and
Process Output Image to the output
SELECTION OF A PLC
Selection of PLC Based on
No of Inputs amp Outputs
Input Voltage
Memory
Scan Time
Special IO modules
Expansion Capabilities
Stand alone or Networked
Communication Capabilities
HOW PLC WORKS
Step 1-CHECKING INPUT STATUS
o PLC Scans each input
o Records the data in work memory
Step 2-EXECUTE PROGRAM
o PLC goes through the program logic step by step
o PLC executes the program depending on input status
o Write the output image in work memory
Step 3-UPDATE OUTPUT STATUS
o Changes the statues of the output onoff
o Again starts the cycle from step one
FEATURES OF S7-200
Allows Your Program to Immediately Read or Write the IO
Allows Your Program to Interrupt the Scan Cycle
Allows You to Allocate Processing Time for Communications
Tasks
Allows You to Set the States of Digital Outputs for Stop
CHECK
INPUT STATUS
EXECUTE
PROGRAM
UPDATE
OUTPUT STATUS
Mode
Allows You to Define Memory to Be Retained on Loss of Power
Allows You to Filter the Digital Inputs
Allows You to Filter the Analog Inputs
Allows You to Catch Pulses of Short Duration
Provides Password Protection
Provides Analog Adjustment Potentiometers
Provides High-speed IO
TECHNICAL FEATURES OF S7-200
Several models of CPUrsquos
o CPU 221 6in4out 2Kw program
o CPU 222 8in6out 2Kw program
o CPU 224 14in10out 4Kw program
o CPU 226 24in16out 4Kw program
Up to 256 digital input-outputs
Up to 32 analog channels
256 timers 256 counters
Built-in EEPROM memory
Real-time clockcalendar
Built-in communications
Password protection
Memory module
Removable input-output connectors
Wide range of expansion modules
o 8 pt input and output
o 4488 amp1616 inout combination
o 4 channel analog in 2 channel analog out
o 4 ch1ch analog inout combination
o 2 channel RTD in
o 4 channel thermocouple in
o PROFIBUS-DP Slave
o AS Interface master
SELECTING THE OPERATING MODE FOR THE S7- 200 CPU
The S7-200 has two modes of operation STOP mode and RUN mode The status LED on the front of the CPU indicates the current mode of operation In STOP mode the S7-200 is not executing the program and you can download a program or the CPU configuration In RUN mode the S7-200 is running the program
1048600 The S7-200 provides a mode switch for changing the mode of operation You can use the mode switch (located under the front access door of the S7-200) to manually select the operating mode setting the mode switch to STOP mode stops the execution of the program setting the mode switch to RUN mode starts the execution of the program and setting the mode switch to TERM (terminal) mode does not change the operating mode
If a power cycle occurs when the mode switch is set to either STOP or TERM the
S7-200 goes automatically to STOP mode when power is restored If a power cycle occurs when the mode switch is set to RUN the S7-200 goes to RUN mode when power is restored
1048600 STEP 7--MicroWIN allows you to change the operating mode of the online S7-200 To enable the software to change the operating mode you must manually set the mode switch on the S7-200 to either TERM or RUN You can use the PLC gt STOP or PLC gt RUN menu commands or the associated buttons on the toolbar to change the operating mode
1048600 You can insert the STOP instruction in your program to change the S7-200 to STOP mode This allows you to halt the execution of your program based on the program logic
ERRORS IN S7-200
Non-Fatal Errors
Non-fatal errors are those indicating problems with the construction of the user program with the execution of an instruction in the user program and with expansion IO modules You can use STEP 7--MicroWIN to view the error codes that were generated by the non-fatal error There are three basic categories of non-fatal errors
Program-compile errorsThe S7-200 compiles the program as it downloads If the S7-200 detects that the program violates a compilation rule the download is aborted and an error code is generated (A program that was already downloaded to the S7-200 would still exist in the EEPROM and would not be lost) After you correct your program you can download it again
IO errorsAt startup the S7-200 reads the IO configuration from each module During normal operation the S7-200 periodically checks the status of each module and compares it against the configuration obtained during startup If the S7-200 detects a difference the S7-200 sets the configuration error bit in the module error register The S7-200 does not read input data from or write output data to that module until the module configuration again matches the one obtained at startupThe module status information is stored in special memory (SM) bits Your program can monitor and evaluate these bits Refer to Appendix D for more information about the SM bits used for reporting IO errors SM50 is the global IO error bit and remains set while an error condition exists on an expansion module
Program execution errorsYour program can create error conditions while being executed These errors can result from improper use of an instruction or from the processing of invalid data by an instruction For example an indirect-address pointer that was valid when the program compiled could be modified during the execution of the program to point to an out-of-range address This is an example of a run-time programming problem SM43 is setupon the occurrence of a run-time programming problem and remains set while the S7-200 is in RUN mode Program execution error information is stored in special memory (SM) bits Your program can monitor and evaluate these bits The S7-200 does not change to STOP mode when it detects a non-fatal error It only logs the event in SM memory and continues with the execution of your program However you can design your program to force the S7-200 to STOP mode when a non-fatal error is detected
Fatal Errors
Fatal errors cause the S7-200 to stop the execution of your program Depending upon the severity of the fatal error it can render the S7-200 incapable of performing any or all functions The objective for handling fatal errors is to bring the S7-200 to a safe state from which the S7-200 can respond to interrogations about the existing error conditions When a fatal error is detected the S7-200 changes to STOP mode turns on the System Fault LED and the STOP LED overrides the output table and turns off the outputsThe S7-200 remains in this condition until the fatal error condition is corrected
Once you have made the changes to correct the fatal error condition use one of the following methods to restart the S7-200 1048600 Turn the power off and then on 1048600 Change the mode switch from RUN or TERM to STOP 1048600 Select the PLC gt Power-Up Reset menu command from STEP 7--MicroWIN
to restart the S7-200This forces the S7-200 to restart and clear any fatal errors
Restarting the S7-200 clears the fatal error condition and performs power-up diagnostic testing to verify that the fatal error has been corrected If another fatal error condition is found the S7-200 again sets the fault LED indicating that an error still exists Otherwise the S7-200 begins normal operation
Some error conditions can render the S7-200 incapable of communication In these cases you cannot view the error code from the S7-200 These types of errors indicate hardware failures that require the S7-200 to be repaired they cannot be fixed by changes to the program or clearing the memory of the S7-200
APPLICATIONS OF S7-200
Conveyer Systems
Elevators
Test Stations
Placement Systems
Woodworking Machinery
Packaging Equipment
Car Wash Automation
Remote Monitoring And Controlling For Water Wastewater
FEATURES OF LADDER DIAGRAMS
The LAD editor displays the program as a graphical representation similar to electrical wiring diagrams
Ladder programs allow the program to emulate the flow of electric current from a power source through a series of logical input conditions that in turn enable logical output conditions
A LAD program includes a left power rail that is energized Contacts that are closed allow energy to flow through them to the next element and contacts that are open block that energy flow
The logic is separated into networks The program is executed one network at a time from left to right and then top to bottom as dictated by the program Figure shows an example of a LAD program
The various instructions are represented by graphic symbols and include three basic forms
Contacts represent logic input conditions such as switches buttons or internal conditions
Coils usually represent logic output results such as lamps motor starters interposing relays or internal output conditions
Boxes represent additional instructions such as timers counters or math instructions Figure Sample LAD Program
Consider these main points when you select the LAD editor 1048600 Ladder logic is easy for beginning programmers to use 1048600 Graphical representation is easy to understand and is popular around the world 1048600 The LAD editor can be used with both the SIMATIC and IEC 1131--3 Instruction sets
1048600 You can always use the STL editor to display a program created with
the SIMATIC LAD editor
COMPONENTS LIST
Cardboard of 4050 sqcm
PLC S7-200
Sensors
LEDS
Buzzers
Motor
Contactors
Power supply
12v DC battery
Connecting wires
PPI Cable
SENSORS
A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact A proximity sensor often emits an electromagnetic or electrostatic field or a beam of electromagnetic radiation (infrared for instance) and looks for changes in the field or return signal The object being sensed is often referred to as the proximity sensors target Different
proximity sensor targets demand different sensors For example a capacitive or photoelectric sensor might be suitable for a plastic target an inductive proximity sensor requires a metal target
The maximum distance that this sensor can detect is defined nominal range Some sensors have adjustments of the nominal range or means to report a graduated detection distance
Proximity sensors can have a high reliability and long functional life because of the absence of mechanical parts and lack of physical contact between sensor and the sensed object
IEC 60947-5-2 defines the technical details of proximity sensors
A proximity sensor adjusted to a very short range is often used as a touch switch
Applications
Car bumpers that sense distance to nearby cars for parking
Ground proximity warning system for aviation safety Vibration Position measurements of rotating shafts in
machinery Sheet break sensing in paper machine Anti-aircraft artillery
LEDS
Example Circuit symbol
FunctionLEDs emit light when an electric current passes through them
Testing an LED
Never connect an LED directly to a battery or power supply
LEDs must have a resistor in series to limit the current to a safe value for quick testing purposes a 1k resistor is suitable for most LEDs if your supply voltage is 12V or less Remember to connect the LED the correct way round
Sizes Shapes and Viewing angles of LEDs
LEDs are available in a wide variety of sizes and shapes The standard LED has a round cross-section of 5mm diameter and this is probably the best type for general use but 3mm round LEDs are also popular
Round cross-section LEDs are frequently used and they are very easy to install on boxes by drilling a hole of the LED diameter adding a spot of glue will help to hold the LED if necessary LED clips are also available to secure LEDs in holes Other cross-section shapes include square rectangular and triangular
As well as a variety of colours sizes and shapes LEDs also vary in their viewing angle This tells you how much the beam of light spreads out Standard LEDs have a viewing angle of 60deg but others have a narrow beam of 30deg or less
Calculating an LED resistor value
An LED must have a resistor connected in series to limit the current through the LED otherwise it will burn out almost instantly
The resistor value R is given by
R = (VS - VL) I
VS = supply voltage VL = LED voltage (usually 2V but 4V for blue and white LEDs) I = LED current (eg 20mA) this must be less than the maximum permitted
If the calculated value is not available choose the nearest standard resistor value which is greater so that the current will be a little less than you chose In fact you may wish to choose a greater resistor value to reduce the current (to increase battery life for example) but this will make the LED less bright
Working out the LED resistor formula using Ohms law
Ohms law says that the resistance of the resistor R = VI where V = voltage across the resistor (= VS - VL in this case) I = the current through the resistor
So R = (VS - VL) I
BUZZERS
A buzzer or beeper (BUZZERS) is a signalling device usually electronic typically used in automobiles household appliances such as a microwave oven or game shows It most commonly consists of a number of switches or sensors connected to a control unit that determines if and which button was pushed or a preset time has lapsed and usually illuminates a light on the appropriate button or control panel and sounds a warning in the form of a continuous or intermittent buzzing
or beeping sound Initially this device was based on an electromechanical system which was identical to an electric bell without the metal gong (which makes the ringing noise) Often these units were anchored to a wall or ceiling and used the ceiling or wall as a sounding board Another implementation with some AC-connected devices was to implement a circuit to make the AC current into a noise loud enough to drive a loudspeaker and hook this circuit up to a cheap 8-ohm speaker Nowadays it is more popular to use a ceramic-based piezoelectric sounder which makes a high-pitched tone Usually these were hooked up to driver circuits which varied the pitch of the sound or pulsed the sound on and off
The word buzzer comes from the rasping noise that buzzers made when they were electromechanical devices operated from stepped-down AC line voltage at 50 or 60 cycles Other sounds commonly used to indicate that a button has been pressed are a ring or a beep
MOTORS
An electric motor is a device using electrical energy to produce mechanical energy nearly always by the interaction of magnetic fields and current-carrying conductors The reverse process that of using mechanical energy to produce electrical energy is accomplished by a generator or dynamo Traction motors used on vehicles often perform both tasks
Electric motors are found in myriad uses such as industrial fans blowers and pumps machine tools household appliances power tools and computer disk drives among
many other applications Electric motors may be operated by direct current from a battery in a portable device or motor vehicle or from alternating current from a central electrical distribution grid The smallest motors may be found in electric wristwatches Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses The very largest electric motors are used for propulsion of large ships and for such purposes as pipeline compressors with ratings in the thousands of kilowatts Electric motors may be classified by the source of electric power by their internal construction and by application
The physical principle of production of mechanical force by the interaction of an electric current and a magnetic field was known as early as 1821 Electric motors of increasing efficiency were constructed throughout the 19th century but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks
CONNECTORS
A DC connector is an electrical connector for
supplying direct current (DC) power DC connectors
are poorly standardized compared to domestic AC
power plugs and sockets DC plug is a common name
used for one common type of cylindrical two-conductor
plug available in a range of sizes and used to power
small pieces of electronic equipment It is also used to
describe some older multi-pin plugs
Several competing standards exist for DC plugs and in some cases incompatible plugs
will fit together to avoid damaging equipment these conditions must be true
Voltage must match
Polarity is correct
Current ratings are sufficient
Power supply filtering and stability is adequate
for the equipment being powered
Non-matching connectors are forced together
12V DC BATTERY
Features
Less than a 12 volt self discharge per 6 months 4 ea 12Vdc outputs 20 AmpHours Built-charger Digital Voltmeter
Description
This unit supplies a full 12Vdc at 20 AmpHours Designed for the officer that needs a power source that can be charged from 115Ac source or on the way to a incident from the car
The battery source has a very low self discharge rate which makes it perfect for law enforcement use The battery can set on the shelf for more than 6 months without recharging
Everyone knows when you grab a battery operated device the internal battery always requires several hours of charging before using The new voltage indicator reads out voltage to one hundredth of a volt for accurate operation The four outputs are 21mm plug Quick terminals and Cigarette lighter jack amp PT02 (Mil Spec) This model also allows powering
12Vdc sources while plugged in to 115Vac ldquoIts a UPSrdquo
SPECIFICATIONS OF COMPONENTS USED
PLC S7-200
INPUT POWER 230V AC 50 Hz
INPUTS 24 DC INPUTS
OUTPUTS 16 DC OUTPUTS
PROGRAM MEMORY 24
DATA MEMORY 10KB
EXPANSION MODULES 7
COMMUNICATION PORTS 2 RS 485
DIGITAL IO IMAGE SIZE 256(128 in 128 out)
EXECUTION SPEED 022microsecondsinstruction
SENSORS
SENSING RANGE 3mm
HOUSING MATERIAL Brass Nickel Plated
OPERATING VOLTAGE 10-30V
OPERATING CURRENT lt200mA
CONNECTION TYPE Cable
LEDS
DIAMETER 5mm
MAXIMUM VOLTAGE 1V
MAXIMUM CURRENT 10mA
INTENSITY
BUZZERS
OPERATING VOLTAGE30Vp-p
RATED FREQUENCY2000Hz 500Hz
OPERATING TEMP RANGE -20 to 60 degree
SOUND OUTPUT70 dB min10 cm
MOTOR
TOTAL LENGTH 46mm MOTOR DIAMETER 36mm MOTOR LENGTH 25mm DC SUPPLY 4 to 12V RPM 100 BRUSH TYPE Precious metal GEAR HEAD DIAMETER 37mm GEAR HEAD LENGTH 21mm OUTPUT SHAFT Centered SHAFT DIAMETER 4mm and 6mm
SHAFT LENGTH 22mm
- Block diagram of plc
- Applications
-
- Function
- Testing an LED
- Sizes Shapes and Viewing angles of LEDs
- Calculating an LED resistor value
-
- Working out the LED resistor formula using Ohms law
-
However some specialty vehicles such as transit busses economically use PLCs instead of custom-designed controls because the volumes are low and the development cost would be uneconomic
Very complex process control such as used in the chemical industry may require algorithms and performance beyond the capability of even high-performance PLCs Very high-speed or precision controls may also require customized solutions for example aircraft flight controls
Programmable controllers are widely used in motion control positioning control and torque control Some manufacturers produce motion control units to be integrated with PLC so that G-code (involving a CNC machine) can be used to instruct machine movements
PLCs may include logic for single-variable feedback analog control loop a proportional integral derivative or PID controller A PID loop could be used to control the temperature of a manufacturing process for example Historically PLCs were usually configured with only a few analog control loops where processes required hundreds or thousands of loops a distributed control system (DCS) would instead be used As PLCs have become more powerful the boundary between DCS and PLC applications has become less distinct
PLCs have similar functionality as Remote Terminal Units An RTU however usually does not support control algorithms or control loops As hardware rapidly becomes more powerful and cheaper RTUs PLCs and DCSs are increasingly beginning to overlap in responsibilities The industry has standardized on the IEC 61131-3 functional block language for creating programs to run on RTUs and PLCs although nearly all vendors also offer proprietary alternatives and associated development environments
DISADVANTAGES OF lsquoHARD WIRED LOGIC CONTROLrsquo
Bulky panels
Complex wiring
Longer project time
Difficult maintenance and troubleshooting
ADVANTAGES OF lsquoPLCSrsquo
Reduced space
Ease of maintenance
Economical
Greater life amp reliability
Tremendous flexibility
Shorter project time
Easier storage archiving and documentation
WHAT CONSTITUTES A PLC
The PLC is programmed interface between the Input field elements amp output field
elements
PLC consist of
Hardware
Input Module
CPU (Central Process Unit)
Program memory
Output module
Power Supply
Software
Application Software (Logic)
Basic Software
Communication Accessories
Communication Adapter
INPUT-OUTPUT
Input and output (IO) modules connect the PLC to
sensors and actuators
Provide isolation for the low-voltage low-current
signals
Wide range of IO modules available including
Digital (logical) IO modules and Analogue (continuous) IO modules
Analogue input cards convert continuous signals via an AD converter into discrete
values for the PLC
Analogue output cards convert digital values in then PLC to continuous signals via a
DA converter
Resolution can be important in choosing an applicable card
Module receptacle for battery EEPROM
CPU statu
s LEDrsquo
sCommunicatio
ns interfa
ce
Status LEDrsquos of
the inputs
and outputs
Fixing holes for wall
mounting
Locking clip for DIN rail mounting
Analog potentiometer
Removable
connection
terminals(on 224 226)
Example for a temperature input of 0 to 100 degrees C
For 8 bit resolution the value in the PLC is 0 to 255
For 12 bit resolution the value in the PLC is 0 to 4095
For 16 bit resolution the value in the PLC is 0 to 32768
SPECIAL MODULES
RF ID
Modem modules
Load Cell
Stepper Modules
Temperature Sensor
High Speed Counters
Position Control Cards
Field Bus Cards
o Device Net Profibus Ethernet etc
ELEMENTS OF INPUTS
Digital Inputs
push button
limit switches
Sensors
o Proximity Sensors
o Photo Sensors
Micro Switches
Toggle Switches
Analog Inputs
Pressure Transmitters
Flow Transmitter
Level Transmitter
Thermo Couples
Load Cell
ELEMENTS OF OUTPUTS
Digital Outputs
Relays
Contactors
Indication Lamps
Valves
Analog Outputs
Flow Control Valves
Pressure Control Valves
Drive Inputs
BASIC ELEMENTS OF A PROGRAM
A program block is composed of executable code and comments The executable codes consist of a main program and any subroutines or interrupt routines The code is compiled and downloaded to the S7-200 the program comments are not You can use the organizational elements (main program subroutines and interrupt routines) to structure your control program
Main ProgramThe main body of the program contains the instructions that control your application The S7-200 executes these instructions sequentially once per scan cycle The main program is also referred to as OB1
SubroutinesThese optional elements of your program are executed only when called by the main program by an interrupt routine or by another subroutine Subroutines are useful in cases where you want to execute a function repeatedly Rather than rewriting the logic for each place in the main program where you want the function to occur you can write the logic once in a subroutine and call the subroutine as many times as needed during the main program Subroutines provide several benefits
1048600 Using subroutines reduces the overall size of your program 1048600 Using subroutines decreases your scan time because you have moved the code out of the main program The S7-200 evaluates the code in the main program every scan cycle whether the code is executed or not but the S7-200 evaluates the code in the subroutine only when you call the subroutine and does not evaluate the code during the scans in which the subroutine is not called 1048600 Using subroutines creates code that is portable You can isolate the code for a function in a subroutine and then copy that subroutine into other programs with Interrupt RoutinesThese optional elements of your program react to specific interrupt events You design an interrupt routine to handle a pre-defined interrupt event Whenever the specified event occurs the S7-200 executes the interrupt routineThe interrupt routines are not called by your main program You associate an interrupt routine with an interrupt event and the S7-200 executes the instructions in the interrupt routine only on each occurrence of the interrupt event Other Elements of the ProgramOther blocks contain information for the S7-200 You can choose to download these blocks when you download your programSystem BlockThe system block allows you to configure different hardware options for the S7-200Data BlockThe data block stores the values for different variables (V memory) used by your program You can use the data block to enter initial values for the data
PROGRAMMING LANGUAGES IN PLC
IL (Instruction List) ndash mnemonic programming
LD (Ladder Diagram) ndash Relay logic
ST (Structured Text) ndash A C like programming language
FDB (Functional Block Diagram) ndash Graphical dataflow programming language
SFC (Sequential Flow Chart) ndash Graphical method for structured programs
Basic PLC Memory
Memory on a PLC is separated into 3 main areas
LOAD Memory
Can be RAM (dynamic) or EEPROM (retentive)
Used to store user programs
WORK Memory
Memory is RAM
When PLC starts Program is copied from LOAD memory to
WORK memory The program is then executed from Work
memory
SYSTEM Memory
Memory is RAM
Is used by micro-controller to implement counters timers interrupt
stacks etc
Contains a bit for each D I0
Contains ldquoMarker Memoryrdquo Marker memory is a free area of RAM
that can be used by the programmer
Contains ldquoProcess Input and Output Imagesrdquo Periodically the PLC
will store the states of the inputs to the Process Input Image and
Process Output Image to the output
SELECTION OF A PLC
Selection of PLC Based on
No of Inputs amp Outputs
Input Voltage
Memory
Scan Time
Special IO modules
Expansion Capabilities
Stand alone or Networked
Communication Capabilities
HOW PLC WORKS
Step 1-CHECKING INPUT STATUS
o PLC Scans each input
o Records the data in work memory
Step 2-EXECUTE PROGRAM
o PLC goes through the program logic step by step
o PLC executes the program depending on input status
o Write the output image in work memory
Step 3-UPDATE OUTPUT STATUS
o Changes the statues of the output onoff
o Again starts the cycle from step one
FEATURES OF S7-200
Allows Your Program to Immediately Read or Write the IO
Allows Your Program to Interrupt the Scan Cycle
Allows You to Allocate Processing Time for Communications
Tasks
Allows You to Set the States of Digital Outputs for Stop
CHECK
INPUT STATUS
EXECUTE
PROGRAM
UPDATE
OUTPUT STATUS
Mode
Allows You to Define Memory to Be Retained on Loss of Power
Allows You to Filter the Digital Inputs
Allows You to Filter the Analog Inputs
Allows You to Catch Pulses of Short Duration
Provides Password Protection
Provides Analog Adjustment Potentiometers
Provides High-speed IO
TECHNICAL FEATURES OF S7-200
Several models of CPUrsquos
o CPU 221 6in4out 2Kw program
o CPU 222 8in6out 2Kw program
o CPU 224 14in10out 4Kw program
o CPU 226 24in16out 4Kw program
Up to 256 digital input-outputs
Up to 32 analog channels
256 timers 256 counters
Built-in EEPROM memory
Real-time clockcalendar
Built-in communications
Password protection
Memory module
Removable input-output connectors
Wide range of expansion modules
o 8 pt input and output
o 4488 amp1616 inout combination
o 4 channel analog in 2 channel analog out
o 4 ch1ch analog inout combination
o 2 channel RTD in
o 4 channel thermocouple in
o PROFIBUS-DP Slave
o AS Interface master
SELECTING THE OPERATING MODE FOR THE S7- 200 CPU
The S7-200 has two modes of operation STOP mode and RUN mode The status LED on the front of the CPU indicates the current mode of operation In STOP mode the S7-200 is not executing the program and you can download a program or the CPU configuration In RUN mode the S7-200 is running the program
1048600 The S7-200 provides a mode switch for changing the mode of operation You can use the mode switch (located under the front access door of the S7-200) to manually select the operating mode setting the mode switch to STOP mode stops the execution of the program setting the mode switch to RUN mode starts the execution of the program and setting the mode switch to TERM (terminal) mode does not change the operating mode
If a power cycle occurs when the mode switch is set to either STOP or TERM the
S7-200 goes automatically to STOP mode when power is restored If a power cycle occurs when the mode switch is set to RUN the S7-200 goes to RUN mode when power is restored
1048600 STEP 7--MicroWIN allows you to change the operating mode of the online S7-200 To enable the software to change the operating mode you must manually set the mode switch on the S7-200 to either TERM or RUN You can use the PLC gt STOP or PLC gt RUN menu commands or the associated buttons on the toolbar to change the operating mode
1048600 You can insert the STOP instruction in your program to change the S7-200 to STOP mode This allows you to halt the execution of your program based on the program logic
ERRORS IN S7-200
Non-Fatal Errors
Non-fatal errors are those indicating problems with the construction of the user program with the execution of an instruction in the user program and with expansion IO modules You can use STEP 7--MicroWIN to view the error codes that were generated by the non-fatal error There are three basic categories of non-fatal errors
Program-compile errorsThe S7-200 compiles the program as it downloads If the S7-200 detects that the program violates a compilation rule the download is aborted and an error code is generated (A program that was already downloaded to the S7-200 would still exist in the EEPROM and would not be lost) After you correct your program you can download it again
IO errorsAt startup the S7-200 reads the IO configuration from each module During normal operation the S7-200 periodically checks the status of each module and compares it against the configuration obtained during startup If the S7-200 detects a difference the S7-200 sets the configuration error bit in the module error register The S7-200 does not read input data from or write output data to that module until the module configuration again matches the one obtained at startupThe module status information is stored in special memory (SM) bits Your program can monitor and evaluate these bits Refer to Appendix D for more information about the SM bits used for reporting IO errors SM50 is the global IO error bit and remains set while an error condition exists on an expansion module
Program execution errorsYour program can create error conditions while being executed These errors can result from improper use of an instruction or from the processing of invalid data by an instruction For example an indirect-address pointer that was valid when the program compiled could be modified during the execution of the program to point to an out-of-range address This is an example of a run-time programming problem SM43 is setupon the occurrence of a run-time programming problem and remains set while the S7-200 is in RUN mode Program execution error information is stored in special memory (SM) bits Your program can monitor and evaluate these bits The S7-200 does not change to STOP mode when it detects a non-fatal error It only logs the event in SM memory and continues with the execution of your program However you can design your program to force the S7-200 to STOP mode when a non-fatal error is detected
Fatal Errors
Fatal errors cause the S7-200 to stop the execution of your program Depending upon the severity of the fatal error it can render the S7-200 incapable of performing any or all functions The objective for handling fatal errors is to bring the S7-200 to a safe state from which the S7-200 can respond to interrogations about the existing error conditions When a fatal error is detected the S7-200 changes to STOP mode turns on the System Fault LED and the STOP LED overrides the output table and turns off the outputsThe S7-200 remains in this condition until the fatal error condition is corrected
Once you have made the changes to correct the fatal error condition use one of the following methods to restart the S7-200 1048600 Turn the power off and then on 1048600 Change the mode switch from RUN or TERM to STOP 1048600 Select the PLC gt Power-Up Reset menu command from STEP 7--MicroWIN
to restart the S7-200This forces the S7-200 to restart and clear any fatal errors
Restarting the S7-200 clears the fatal error condition and performs power-up diagnostic testing to verify that the fatal error has been corrected If another fatal error condition is found the S7-200 again sets the fault LED indicating that an error still exists Otherwise the S7-200 begins normal operation
Some error conditions can render the S7-200 incapable of communication In these cases you cannot view the error code from the S7-200 These types of errors indicate hardware failures that require the S7-200 to be repaired they cannot be fixed by changes to the program or clearing the memory of the S7-200
APPLICATIONS OF S7-200
Conveyer Systems
Elevators
Test Stations
Placement Systems
Woodworking Machinery
Packaging Equipment
Car Wash Automation
Remote Monitoring And Controlling For Water Wastewater
FEATURES OF LADDER DIAGRAMS
The LAD editor displays the program as a graphical representation similar to electrical wiring diagrams
Ladder programs allow the program to emulate the flow of electric current from a power source through a series of logical input conditions that in turn enable logical output conditions
A LAD program includes a left power rail that is energized Contacts that are closed allow energy to flow through them to the next element and contacts that are open block that energy flow
The logic is separated into networks The program is executed one network at a time from left to right and then top to bottom as dictated by the program Figure shows an example of a LAD program
The various instructions are represented by graphic symbols and include three basic forms
Contacts represent logic input conditions such as switches buttons or internal conditions
Coils usually represent logic output results such as lamps motor starters interposing relays or internal output conditions
Boxes represent additional instructions such as timers counters or math instructions Figure Sample LAD Program
Consider these main points when you select the LAD editor 1048600 Ladder logic is easy for beginning programmers to use 1048600 Graphical representation is easy to understand and is popular around the world 1048600 The LAD editor can be used with both the SIMATIC and IEC 1131--3 Instruction sets
1048600 You can always use the STL editor to display a program created with
the SIMATIC LAD editor
COMPONENTS LIST
Cardboard of 4050 sqcm
PLC S7-200
Sensors
LEDS
Buzzers
Motor
Contactors
Power supply
12v DC battery
Connecting wires
PPI Cable
SENSORS
A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact A proximity sensor often emits an electromagnetic or electrostatic field or a beam of electromagnetic radiation (infrared for instance) and looks for changes in the field or return signal The object being sensed is often referred to as the proximity sensors target Different
proximity sensor targets demand different sensors For example a capacitive or photoelectric sensor might be suitable for a plastic target an inductive proximity sensor requires a metal target
The maximum distance that this sensor can detect is defined nominal range Some sensors have adjustments of the nominal range or means to report a graduated detection distance
Proximity sensors can have a high reliability and long functional life because of the absence of mechanical parts and lack of physical contact between sensor and the sensed object
IEC 60947-5-2 defines the technical details of proximity sensors
A proximity sensor adjusted to a very short range is often used as a touch switch
Applications
Car bumpers that sense distance to nearby cars for parking
Ground proximity warning system for aviation safety Vibration Position measurements of rotating shafts in
machinery Sheet break sensing in paper machine Anti-aircraft artillery
LEDS
Example Circuit symbol
FunctionLEDs emit light when an electric current passes through them
Testing an LED
Never connect an LED directly to a battery or power supply
LEDs must have a resistor in series to limit the current to a safe value for quick testing purposes a 1k resistor is suitable for most LEDs if your supply voltage is 12V or less Remember to connect the LED the correct way round
Sizes Shapes and Viewing angles of LEDs
LEDs are available in a wide variety of sizes and shapes The standard LED has a round cross-section of 5mm diameter and this is probably the best type for general use but 3mm round LEDs are also popular
Round cross-section LEDs are frequently used and they are very easy to install on boxes by drilling a hole of the LED diameter adding a spot of glue will help to hold the LED if necessary LED clips are also available to secure LEDs in holes Other cross-section shapes include square rectangular and triangular
As well as a variety of colours sizes and shapes LEDs also vary in their viewing angle This tells you how much the beam of light spreads out Standard LEDs have a viewing angle of 60deg but others have a narrow beam of 30deg or less
Calculating an LED resistor value
An LED must have a resistor connected in series to limit the current through the LED otherwise it will burn out almost instantly
The resistor value R is given by
R = (VS - VL) I
VS = supply voltage VL = LED voltage (usually 2V but 4V for blue and white LEDs) I = LED current (eg 20mA) this must be less than the maximum permitted
If the calculated value is not available choose the nearest standard resistor value which is greater so that the current will be a little less than you chose In fact you may wish to choose a greater resistor value to reduce the current (to increase battery life for example) but this will make the LED less bright
Working out the LED resistor formula using Ohms law
Ohms law says that the resistance of the resistor R = VI where V = voltage across the resistor (= VS - VL in this case) I = the current through the resistor
So R = (VS - VL) I
BUZZERS
A buzzer or beeper (BUZZERS) is a signalling device usually electronic typically used in automobiles household appliances such as a microwave oven or game shows It most commonly consists of a number of switches or sensors connected to a control unit that determines if and which button was pushed or a preset time has lapsed and usually illuminates a light on the appropriate button or control panel and sounds a warning in the form of a continuous or intermittent buzzing
or beeping sound Initially this device was based on an electromechanical system which was identical to an electric bell without the metal gong (which makes the ringing noise) Often these units were anchored to a wall or ceiling and used the ceiling or wall as a sounding board Another implementation with some AC-connected devices was to implement a circuit to make the AC current into a noise loud enough to drive a loudspeaker and hook this circuit up to a cheap 8-ohm speaker Nowadays it is more popular to use a ceramic-based piezoelectric sounder which makes a high-pitched tone Usually these were hooked up to driver circuits which varied the pitch of the sound or pulsed the sound on and off
The word buzzer comes from the rasping noise that buzzers made when they were electromechanical devices operated from stepped-down AC line voltage at 50 or 60 cycles Other sounds commonly used to indicate that a button has been pressed are a ring or a beep
MOTORS
An electric motor is a device using electrical energy to produce mechanical energy nearly always by the interaction of magnetic fields and current-carrying conductors The reverse process that of using mechanical energy to produce electrical energy is accomplished by a generator or dynamo Traction motors used on vehicles often perform both tasks
Electric motors are found in myriad uses such as industrial fans blowers and pumps machine tools household appliances power tools and computer disk drives among
many other applications Electric motors may be operated by direct current from a battery in a portable device or motor vehicle or from alternating current from a central electrical distribution grid The smallest motors may be found in electric wristwatches Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses The very largest electric motors are used for propulsion of large ships and for such purposes as pipeline compressors with ratings in the thousands of kilowatts Electric motors may be classified by the source of electric power by their internal construction and by application
The physical principle of production of mechanical force by the interaction of an electric current and a magnetic field was known as early as 1821 Electric motors of increasing efficiency were constructed throughout the 19th century but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks
CONNECTORS
A DC connector is an electrical connector for
supplying direct current (DC) power DC connectors
are poorly standardized compared to domestic AC
power plugs and sockets DC plug is a common name
used for one common type of cylindrical two-conductor
plug available in a range of sizes and used to power
small pieces of electronic equipment It is also used to
describe some older multi-pin plugs
Several competing standards exist for DC plugs and in some cases incompatible plugs
will fit together to avoid damaging equipment these conditions must be true
Voltage must match
Polarity is correct
Current ratings are sufficient
Power supply filtering and stability is adequate
for the equipment being powered
Non-matching connectors are forced together
12V DC BATTERY
Features
Less than a 12 volt self discharge per 6 months 4 ea 12Vdc outputs 20 AmpHours Built-charger Digital Voltmeter
Description
This unit supplies a full 12Vdc at 20 AmpHours Designed for the officer that needs a power source that can be charged from 115Ac source or on the way to a incident from the car
The battery source has a very low self discharge rate which makes it perfect for law enforcement use The battery can set on the shelf for more than 6 months without recharging
Everyone knows when you grab a battery operated device the internal battery always requires several hours of charging before using The new voltage indicator reads out voltage to one hundredth of a volt for accurate operation The four outputs are 21mm plug Quick terminals and Cigarette lighter jack amp PT02 (Mil Spec) This model also allows powering
12Vdc sources while plugged in to 115Vac ldquoIts a UPSrdquo
SPECIFICATIONS OF COMPONENTS USED
PLC S7-200
INPUT POWER 230V AC 50 Hz
INPUTS 24 DC INPUTS
OUTPUTS 16 DC OUTPUTS
PROGRAM MEMORY 24
DATA MEMORY 10KB
EXPANSION MODULES 7
COMMUNICATION PORTS 2 RS 485
DIGITAL IO IMAGE SIZE 256(128 in 128 out)
EXECUTION SPEED 022microsecondsinstruction
SENSORS
SENSING RANGE 3mm
HOUSING MATERIAL Brass Nickel Plated
OPERATING VOLTAGE 10-30V
OPERATING CURRENT lt200mA
CONNECTION TYPE Cable
LEDS
DIAMETER 5mm
MAXIMUM VOLTAGE 1V
MAXIMUM CURRENT 10mA
INTENSITY
BUZZERS
OPERATING VOLTAGE30Vp-p
RATED FREQUENCY2000Hz 500Hz
OPERATING TEMP RANGE -20 to 60 degree
SOUND OUTPUT70 dB min10 cm
MOTOR
TOTAL LENGTH 46mm MOTOR DIAMETER 36mm MOTOR LENGTH 25mm DC SUPPLY 4 to 12V RPM 100 BRUSH TYPE Precious metal GEAR HEAD DIAMETER 37mm GEAR HEAD LENGTH 21mm OUTPUT SHAFT Centered SHAFT DIAMETER 4mm and 6mm
SHAFT LENGTH 22mm
- Block diagram of plc
- Applications
-
- Function
- Testing an LED
- Sizes Shapes and Viewing angles of LEDs
- Calculating an LED resistor value
-
- Working out the LED resistor formula using Ohms law
-
ADVANTAGES OF lsquoPLCSrsquo
Reduced space
Ease of maintenance
Economical
Greater life amp reliability
Tremendous flexibility
Shorter project time
Easier storage archiving and documentation
WHAT CONSTITUTES A PLC
The PLC is programmed interface between the Input field elements amp output field
elements
PLC consist of
Hardware
Input Module
CPU (Central Process Unit)
Program memory
Output module
Power Supply
Software
Application Software (Logic)
Basic Software
Communication Accessories
Communication Adapter
INPUT-OUTPUT
Input and output (IO) modules connect the PLC to
sensors and actuators
Provide isolation for the low-voltage low-current
signals
Wide range of IO modules available including
Digital (logical) IO modules and Analogue (continuous) IO modules
Analogue input cards convert continuous signals via an AD converter into discrete
values for the PLC
Analogue output cards convert digital values in then PLC to continuous signals via a
DA converter
Resolution can be important in choosing an applicable card
Module receptacle for battery EEPROM
CPU statu
s LEDrsquo
sCommunicatio
ns interfa
ce
Status LEDrsquos of
the inputs
and outputs
Fixing holes for wall
mounting
Locking clip for DIN rail mounting
Analog potentiometer
Removable
connection
terminals(on 224 226)
Example for a temperature input of 0 to 100 degrees C
For 8 bit resolution the value in the PLC is 0 to 255
For 12 bit resolution the value in the PLC is 0 to 4095
For 16 bit resolution the value in the PLC is 0 to 32768
SPECIAL MODULES
RF ID
Modem modules
Load Cell
Stepper Modules
Temperature Sensor
High Speed Counters
Position Control Cards
Field Bus Cards
o Device Net Profibus Ethernet etc
ELEMENTS OF INPUTS
Digital Inputs
push button
limit switches
Sensors
o Proximity Sensors
o Photo Sensors
Micro Switches
Toggle Switches
Analog Inputs
Pressure Transmitters
Flow Transmitter
Level Transmitter
Thermo Couples
Load Cell
ELEMENTS OF OUTPUTS
Digital Outputs
Relays
Contactors
Indication Lamps
Valves
Analog Outputs
Flow Control Valves
Pressure Control Valves
Drive Inputs
BASIC ELEMENTS OF A PROGRAM
A program block is composed of executable code and comments The executable codes consist of a main program and any subroutines or interrupt routines The code is compiled and downloaded to the S7-200 the program comments are not You can use the organizational elements (main program subroutines and interrupt routines) to structure your control program
Main ProgramThe main body of the program contains the instructions that control your application The S7-200 executes these instructions sequentially once per scan cycle The main program is also referred to as OB1
SubroutinesThese optional elements of your program are executed only when called by the main program by an interrupt routine or by another subroutine Subroutines are useful in cases where you want to execute a function repeatedly Rather than rewriting the logic for each place in the main program where you want the function to occur you can write the logic once in a subroutine and call the subroutine as many times as needed during the main program Subroutines provide several benefits
1048600 Using subroutines reduces the overall size of your program 1048600 Using subroutines decreases your scan time because you have moved the code out of the main program The S7-200 evaluates the code in the main program every scan cycle whether the code is executed or not but the S7-200 evaluates the code in the subroutine only when you call the subroutine and does not evaluate the code during the scans in which the subroutine is not called 1048600 Using subroutines creates code that is portable You can isolate the code for a function in a subroutine and then copy that subroutine into other programs with Interrupt RoutinesThese optional elements of your program react to specific interrupt events You design an interrupt routine to handle a pre-defined interrupt event Whenever the specified event occurs the S7-200 executes the interrupt routineThe interrupt routines are not called by your main program You associate an interrupt routine with an interrupt event and the S7-200 executes the instructions in the interrupt routine only on each occurrence of the interrupt event Other Elements of the ProgramOther blocks contain information for the S7-200 You can choose to download these blocks when you download your programSystem BlockThe system block allows you to configure different hardware options for the S7-200Data BlockThe data block stores the values for different variables (V memory) used by your program You can use the data block to enter initial values for the data
PROGRAMMING LANGUAGES IN PLC
IL (Instruction List) ndash mnemonic programming
LD (Ladder Diagram) ndash Relay logic
ST (Structured Text) ndash A C like programming language
FDB (Functional Block Diagram) ndash Graphical dataflow programming language
SFC (Sequential Flow Chart) ndash Graphical method for structured programs
Basic PLC Memory
Memory on a PLC is separated into 3 main areas
LOAD Memory
Can be RAM (dynamic) or EEPROM (retentive)
Used to store user programs
WORK Memory
Memory is RAM
When PLC starts Program is copied from LOAD memory to
WORK memory The program is then executed from Work
memory
SYSTEM Memory
Memory is RAM
Is used by micro-controller to implement counters timers interrupt
stacks etc
Contains a bit for each D I0
Contains ldquoMarker Memoryrdquo Marker memory is a free area of RAM
that can be used by the programmer
Contains ldquoProcess Input and Output Imagesrdquo Periodically the PLC
will store the states of the inputs to the Process Input Image and
Process Output Image to the output
SELECTION OF A PLC
Selection of PLC Based on
No of Inputs amp Outputs
Input Voltage
Memory
Scan Time
Special IO modules
Expansion Capabilities
Stand alone or Networked
Communication Capabilities
HOW PLC WORKS
Step 1-CHECKING INPUT STATUS
o PLC Scans each input
o Records the data in work memory
Step 2-EXECUTE PROGRAM
o PLC goes through the program logic step by step
o PLC executes the program depending on input status
o Write the output image in work memory
Step 3-UPDATE OUTPUT STATUS
o Changes the statues of the output onoff
o Again starts the cycle from step one
FEATURES OF S7-200
Allows Your Program to Immediately Read or Write the IO
Allows Your Program to Interrupt the Scan Cycle
Allows You to Allocate Processing Time for Communications
Tasks
Allows You to Set the States of Digital Outputs for Stop
CHECK
INPUT STATUS
EXECUTE
PROGRAM
UPDATE
OUTPUT STATUS
Mode
Allows You to Define Memory to Be Retained on Loss of Power
Allows You to Filter the Digital Inputs
Allows You to Filter the Analog Inputs
Allows You to Catch Pulses of Short Duration
Provides Password Protection
Provides Analog Adjustment Potentiometers
Provides High-speed IO
TECHNICAL FEATURES OF S7-200
Several models of CPUrsquos
o CPU 221 6in4out 2Kw program
o CPU 222 8in6out 2Kw program
o CPU 224 14in10out 4Kw program
o CPU 226 24in16out 4Kw program
Up to 256 digital input-outputs
Up to 32 analog channels
256 timers 256 counters
Built-in EEPROM memory
Real-time clockcalendar
Built-in communications
Password protection
Memory module
Removable input-output connectors
Wide range of expansion modules
o 8 pt input and output
o 4488 amp1616 inout combination
o 4 channel analog in 2 channel analog out
o 4 ch1ch analog inout combination
o 2 channel RTD in
o 4 channel thermocouple in
o PROFIBUS-DP Slave
o AS Interface master
SELECTING THE OPERATING MODE FOR THE S7- 200 CPU
The S7-200 has two modes of operation STOP mode and RUN mode The status LED on the front of the CPU indicates the current mode of operation In STOP mode the S7-200 is not executing the program and you can download a program or the CPU configuration In RUN mode the S7-200 is running the program
1048600 The S7-200 provides a mode switch for changing the mode of operation You can use the mode switch (located under the front access door of the S7-200) to manually select the operating mode setting the mode switch to STOP mode stops the execution of the program setting the mode switch to RUN mode starts the execution of the program and setting the mode switch to TERM (terminal) mode does not change the operating mode
If a power cycle occurs when the mode switch is set to either STOP or TERM the
S7-200 goes automatically to STOP mode when power is restored If a power cycle occurs when the mode switch is set to RUN the S7-200 goes to RUN mode when power is restored
1048600 STEP 7--MicroWIN allows you to change the operating mode of the online S7-200 To enable the software to change the operating mode you must manually set the mode switch on the S7-200 to either TERM or RUN You can use the PLC gt STOP or PLC gt RUN menu commands or the associated buttons on the toolbar to change the operating mode
1048600 You can insert the STOP instruction in your program to change the S7-200 to STOP mode This allows you to halt the execution of your program based on the program logic
ERRORS IN S7-200
Non-Fatal Errors
Non-fatal errors are those indicating problems with the construction of the user program with the execution of an instruction in the user program and with expansion IO modules You can use STEP 7--MicroWIN to view the error codes that were generated by the non-fatal error There are three basic categories of non-fatal errors
Program-compile errorsThe S7-200 compiles the program as it downloads If the S7-200 detects that the program violates a compilation rule the download is aborted and an error code is generated (A program that was already downloaded to the S7-200 would still exist in the EEPROM and would not be lost) After you correct your program you can download it again
IO errorsAt startup the S7-200 reads the IO configuration from each module During normal operation the S7-200 periodically checks the status of each module and compares it against the configuration obtained during startup If the S7-200 detects a difference the S7-200 sets the configuration error bit in the module error register The S7-200 does not read input data from or write output data to that module until the module configuration again matches the one obtained at startupThe module status information is stored in special memory (SM) bits Your program can monitor and evaluate these bits Refer to Appendix D for more information about the SM bits used for reporting IO errors SM50 is the global IO error bit and remains set while an error condition exists on an expansion module
Program execution errorsYour program can create error conditions while being executed These errors can result from improper use of an instruction or from the processing of invalid data by an instruction For example an indirect-address pointer that was valid when the program compiled could be modified during the execution of the program to point to an out-of-range address This is an example of a run-time programming problem SM43 is setupon the occurrence of a run-time programming problem and remains set while the S7-200 is in RUN mode Program execution error information is stored in special memory (SM) bits Your program can monitor and evaluate these bits The S7-200 does not change to STOP mode when it detects a non-fatal error It only logs the event in SM memory and continues with the execution of your program However you can design your program to force the S7-200 to STOP mode when a non-fatal error is detected
Fatal Errors
Fatal errors cause the S7-200 to stop the execution of your program Depending upon the severity of the fatal error it can render the S7-200 incapable of performing any or all functions The objective for handling fatal errors is to bring the S7-200 to a safe state from which the S7-200 can respond to interrogations about the existing error conditions When a fatal error is detected the S7-200 changes to STOP mode turns on the System Fault LED and the STOP LED overrides the output table and turns off the outputsThe S7-200 remains in this condition until the fatal error condition is corrected
Once you have made the changes to correct the fatal error condition use one of the following methods to restart the S7-200 1048600 Turn the power off and then on 1048600 Change the mode switch from RUN or TERM to STOP 1048600 Select the PLC gt Power-Up Reset menu command from STEP 7--MicroWIN
to restart the S7-200This forces the S7-200 to restart and clear any fatal errors
Restarting the S7-200 clears the fatal error condition and performs power-up diagnostic testing to verify that the fatal error has been corrected If another fatal error condition is found the S7-200 again sets the fault LED indicating that an error still exists Otherwise the S7-200 begins normal operation
Some error conditions can render the S7-200 incapable of communication In these cases you cannot view the error code from the S7-200 These types of errors indicate hardware failures that require the S7-200 to be repaired they cannot be fixed by changes to the program or clearing the memory of the S7-200
APPLICATIONS OF S7-200
Conveyer Systems
Elevators
Test Stations
Placement Systems
Woodworking Machinery
Packaging Equipment
Car Wash Automation
Remote Monitoring And Controlling For Water Wastewater
FEATURES OF LADDER DIAGRAMS
The LAD editor displays the program as a graphical representation similar to electrical wiring diagrams
Ladder programs allow the program to emulate the flow of electric current from a power source through a series of logical input conditions that in turn enable logical output conditions
A LAD program includes a left power rail that is energized Contacts that are closed allow energy to flow through them to the next element and contacts that are open block that energy flow
The logic is separated into networks The program is executed one network at a time from left to right and then top to bottom as dictated by the program Figure shows an example of a LAD program
The various instructions are represented by graphic symbols and include three basic forms
Contacts represent logic input conditions such as switches buttons or internal conditions
Coils usually represent logic output results such as lamps motor starters interposing relays or internal output conditions
Boxes represent additional instructions such as timers counters or math instructions Figure Sample LAD Program
Consider these main points when you select the LAD editor 1048600 Ladder logic is easy for beginning programmers to use 1048600 Graphical representation is easy to understand and is popular around the world 1048600 The LAD editor can be used with both the SIMATIC and IEC 1131--3 Instruction sets
1048600 You can always use the STL editor to display a program created with
the SIMATIC LAD editor
COMPONENTS LIST
Cardboard of 4050 sqcm
PLC S7-200
Sensors
LEDS
Buzzers
Motor
Contactors
Power supply
12v DC battery
Connecting wires
PPI Cable
SENSORS
A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact A proximity sensor often emits an electromagnetic or electrostatic field or a beam of electromagnetic radiation (infrared for instance) and looks for changes in the field or return signal The object being sensed is often referred to as the proximity sensors target Different
proximity sensor targets demand different sensors For example a capacitive or photoelectric sensor might be suitable for a plastic target an inductive proximity sensor requires a metal target
The maximum distance that this sensor can detect is defined nominal range Some sensors have adjustments of the nominal range or means to report a graduated detection distance
Proximity sensors can have a high reliability and long functional life because of the absence of mechanical parts and lack of physical contact between sensor and the sensed object
IEC 60947-5-2 defines the technical details of proximity sensors
A proximity sensor adjusted to a very short range is often used as a touch switch
Applications
Car bumpers that sense distance to nearby cars for parking
Ground proximity warning system for aviation safety Vibration Position measurements of rotating shafts in
machinery Sheet break sensing in paper machine Anti-aircraft artillery
LEDS
Example Circuit symbol
FunctionLEDs emit light when an electric current passes through them
Testing an LED
Never connect an LED directly to a battery or power supply
LEDs must have a resistor in series to limit the current to a safe value for quick testing purposes a 1k resistor is suitable for most LEDs if your supply voltage is 12V or less Remember to connect the LED the correct way round
Sizes Shapes and Viewing angles of LEDs
LEDs are available in a wide variety of sizes and shapes The standard LED has a round cross-section of 5mm diameter and this is probably the best type for general use but 3mm round LEDs are also popular
Round cross-section LEDs are frequently used and they are very easy to install on boxes by drilling a hole of the LED diameter adding a spot of glue will help to hold the LED if necessary LED clips are also available to secure LEDs in holes Other cross-section shapes include square rectangular and triangular
As well as a variety of colours sizes and shapes LEDs also vary in their viewing angle This tells you how much the beam of light spreads out Standard LEDs have a viewing angle of 60deg but others have a narrow beam of 30deg or less
Calculating an LED resistor value
An LED must have a resistor connected in series to limit the current through the LED otherwise it will burn out almost instantly
The resistor value R is given by
R = (VS - VL) I
VS = supply voltage VL = LED voltage (usually 2V but 4V for blue and white LEDs) I = LED current (eg 20mA) this must be less than the maximum permitted
If the calculated value is not available choose the nearest standard resistor value which is greater so that the current will be a little less than you chose In fact you may wish to choose a greater resistor value to reduce the current (to increase battery life for example) but this will make the LED less bright
Working out the LED resistor formula using Ohms law
Ohms law says that the resistance of the resistor R = VI where V = voltage across the resistor (= VS - VL in this case) I = the current through the resistor
So R = (VS - VL) I
BUZZERS
A buzzer or beeper (BUZZERS) is a signalling device usually electronic typically used in automobiles household appliances such as a microwave oven or game shows It most commonly consists of a number of switches or sensors connected to a control unit that determines if and which button was pushed or a preset time has lapsed and usually illuminates a light on the appropriate button or control panel and sounds a warning in the form of a continuous or intermittent buzzing
or beeping sound Initially this device was based on an electromechanical system which was identical to an electric bell without the metal gong (which makes the ringing noise) Often these units were anchored to a wall or ceiling and used the ceiling or wall as a sounding board Another implementation with some AC-connected devices was to implement a circuit to make the AC current into a noise loud enough to drive a loudspeaker and hook this circuit up to a cheap 8-ohm speaker Nowadays it is more popular to use a ceramic-based piezoelectric sounder which makes a high-pitched tone Usually these were hooked up to driver circuits which varied the pitch of the sound or pulsed the sound on and off
The word buzzer comes from the rasping noise that buzzers made when they were electromechanical devices operated from stepped-down AC line voltage at 50 or 60 cycles Other sounds commonly used to indicate that a button has been pressed are a ring or a beep
MOTORS
An electric motor is a device using electrical energy to produce mechanical energy nearly always by the interaction of magnetic fields and current-carrying conductors The reverse process that of using mechanical energy to produce electrical energy is accomplished by a generator or dynamo Traction motors used on vehicles often perform both tasks
Electric motors are found in myriad uses such as industrial fans blowers and pumps machine tools household appliances power tools and computer disk drives among
many other applications Electric motors may be operated by direct current from a battery in a portable device or motor vehicle or from alternating current from a central electrical distribution grid The smallest motors may be found in electric wristwatches Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses The very largest electric motors are used for propulsion of large ships and for such purposes as pipeline compressors with ratings in the thousands of kilowatts Electric motors may be classified by the source of electric power by their internal construction and by application
The physical principle of production of mechanical force by the interaction of an electric current and a magnetic field was known as early as 1821 Electric motors of increasing efficiency were constructed throughout the 19th century but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks
CONNECTORS
A DC connector is an electrical connector for
supplying direct current (DC) power DC connectors
are poorly standardized compared to domestic AC
power plugs and sockets DC plug is a common name
used for one common type of cylindrical two-conductor
plug available in a range of sizes and used to power
small pieces of electronic equipment It is also used to
describe some older multi-pin plugs
Several competing standards exist for DC plugs and in some cases incompatible plugs
will fit together to avoid damaging equipment these conditions must be true
Voltage must match
Polarity is correct
Current ratings are sufficient
Power supply filtering and stability is adequate
for the equipment being powered
Non-matching connectors are forced together
12V DC BATTERY
Features
Less than a 12 volt self discharge per 6 months 4 ea 12Vdc outputs 20 AmpHours Built-charger Digital Voltmeter
Description
This unit supplies a full 12Vdc at 20 AmpHours Designed for the officer that needs a power source that can be charged from 115Ac source or on the way to a incident from the car
The battery source has a very low self discharge rate which makes it perfect for law enforcement use The battery can set on the shelf for more than 6 months without recharging
Everyone knows when you grab a battery operated device the internal battery always requires several hours of charging before using The new voltage indicator reads out voltage to one hundredth of a volt for accurate operation The four outputs are 21mm plug Quick terminals and Cigarette lighter jack amp PT02 (Mil Spec) This model also allows powering
12Vdc sources while plugged in to 115Vac ldquoIts a UPSrdquo
SPECIFICATIONS OF COMPONENTS USED
PLC S7-200
INPUT POWER 230V AC 50 Hz
INPUTS 24 DC INPUTS
OUTPUTS 16 DC OUTPUTS
PROGRAM MEMORY 24
DATA MEMORY 10KB
EXPANSION MODULES 7
COMMUNICATION PORTS 2 RS 485
DIGITAL IO IMAGE SIZE 256(128 in 128 out)
EXECUTION SPEED 022microsecondsinstruction
SENSORS
SENSING RANGE 3mm
HOUSING MATERIAL Brass Nickel Plated
OPERATING VOLTAGE 10-30V
OPERATING CURRENT lt200mA
CONNECTION TYPE Cable
LEDS
DIAMETER 5mm
MAXIMUM VOLTAGE 1V
MAXIMUM CURRENT 10mA
INTENSITY
BUZZERS
OPERATING VOLTAGE30Vp-p
RATED FREQUENCY2000Hz 500Hz
OPERATING TEMP RANGE -20 to 60 degree
SOUND OUTPUT70 dB min10 cm
MOTOR
TOTAL LENGTH 46mm MOTOR DIAMETER 36mm MOTOR LENGTH 25mm DC SUPPLY 4 to 12V RPM 100 BRUSH TYPE Precious metal GEAR HEAD DIAMETER 37mm GEAR HEAD LENGTH 21mm OUTPUT SHAFT Centered SHAFT DIAMETER 4mm and 6mm
SHAFT LENGTH 22mm
- Block diagram of plc
- Applications
-
- Function
- Testing an LED
- Sizes Shapes and Viewing angles of LEDs
- Calculating an LED resistor value
-
- Working out the LED resistor formula using Ohms law
-
Output module
Power Supply
Software
Application Software (Logic)
Basic Software
Communication Accessories
Communication Adapter
INPUT-OUTPUT
Input and output (IO) modules connect the PLC to
sensors and actuators
Provide isolation for the low-voltage low-current
signals
Wide range of IO modules available including
Digital (logical) IO modules and Analogue (continuous) IO modules
Analogue input cards convert continuous signals via an AD converter into discrete
values for the PLC
Analogue output cards convert digital values in then PLC to continuous signals via a
DA converter
Resolution can be important in choosing an applicable card
Module receptacle for battery EEPROM
CPU statu
s LEDrsquo
sCommunicatio
ns interfa
ce
Status LEDrsquos of
the inputs
and outputs
Fixing holes for wall
mounting
Locking clip for DIN rail mounting
Analog potentiometer
Removable
connection
terminals(on 224 226)
Example for a temperature input of 0 to 100 degrees C
For 8 bit resolution the value in the PLC is 0 to 255
For 12 bit resolution the value in the PLC is 0 to 4095
For 16 bit resolution the value in the PLC is 0 to 32768
SPECIAL MODULES
RF ID
Modem modules
Load Cell
Stepper Modules
Temperature Sensor
High Speed Counters
Position Control Cards
Field Bus Cards
o Device Net Profibus Ethernet etc
ELEMENTS OF INPUTS
Digital Inputs
push button
limit switches
Sensors
o Proximity Sensors
o Photo Sensors
Micro Switches
Toggle Switches
Analog Inputs
Pressure Transmitters
Flow Transmitter
Level Transmitter
Thermo Couples
Load Cell
ELEMENTS OF OUTPUTS
Digital Outputs
Relays
Contactors
Indication Lamps
Valves
Analog Outputs
Flow Control Valves
Pressure Control Valves
Drive Inputs
BASIC ELEMENTS OF A PROGRAM
A program block is composed of executable code and comments The executable codes consist of a main program and any subroutines or interrupt routines The code is compiled and downloaded to the S7-200 the program comments are not You can use the organizational elements (main program subroutines and interrupt routines) to structure your control program
Main ProgramThe main body of the program contains the instructions that control your application The S7-200 executes these instructions sequentially once per scan cycle The main program is also referred to as OB1
SubroutinesThese optional elements of your program are executed only when called by the main program by an interrupt routine or by another subroutine Subroutines are useful in cases where you want to execute a function repeatedly Rather than rewriting the logic for each place in the main program where you want the function to occur you can write the logic once in a subroutine and call the subroutine as many times as needed during the main program Subroutines provide several benefits
1048600 Using subroutines reduces the overall size of your program 1048600 Using subroutines decreases your scan time because you have moved the code out of the main program The S7-200 evaluates the code in the main program every scan cycle whether the code is executed or not but the S7-200 evaluates the code in the subroutine only when you call the subroutine and does not evaluate the code during the scans in which the subroutine is not called 1048600 Using subroutines creates code that is portable You can isolate the code for a function in a subroutine and then copy that subroutine into other programs with Interrupt RoutinesThese optional elements of your program react to specific interrupt events You design an interrupt routine to handle a pre-defined interrupt event Whenever the specified event occurs the S7-200 executes the interrupt routineThe interrupt routines are not called by your main program You associate an interrupt routine with an interrupt event and the S7-200 executes the instructions in the interrupt routine only on each occurrence of the interrupt event Other Elements of the ProgramOther blocks contain information for the S7-200 You can choose to download these blocks when you download your programSystem BlockThe system block allows you to configure different hardware options for the S7-200Data BlockThe data block stores the values for different variables (V memory) used by your program You can use the data block to enter initial values for the data
PROGRAMMING LANGUAGES IN PLC
IL (Instruction List) ndash mnemonic programming
LD (Ladder Diagram) ndash Relay logic
ST (Structured Text) ndash A C like programming language
FDB (Functional Block Diagram) ndash Graphical dataflow programming language
SFC (Sequential Flow Chart) ndash Graphical method for structured programs
Basic PLC Memory
Memory on a PLC is separated into 3 main areas
LOAD Memory
Can be RAM (dynamic) or EEPROM (retentive)
Used to store user programs
WORK Memory
Memory is RAM
When PLC starts Program is copied from LOAD memory to
WORK memory The program is then executed from Work
memory
SYSTEM Memory
Memory is RAM
Is used by micro-controller to implement counters timers interrupt
stacks etc
Contains a bit for each D I0
Contains ldquoMarker Memoryrdquo Marker memory is a free area of RAM
that can be used by the programmer
Contains ldquoProcess Input and Output Imagesrdquo Periodically the PLC
will store the states of the inputs to the Process Input Image and
Process Output Image to the output
SELECTION OF A PLC
Selection of PLC Based on
No of Inputs amp Outputs
Input Voltage
Memory
Scan Time
Special IO modules
Expansion Capabilities
Stand alone or Networked
Communication Capabilities
HOW PLC WORKS
Step 1-CHECKING INPUT STATUS
o PLC Scans each input
o Records the data in work memory
Step 2-EXECUTE PROGRAM
o PLC goes through the program logic step by step
o PLC executes the program depending on input status
o Write the output image in work memory
Step 3-UPDATE OUTPUT STATUS
o Changes the statues of the output onoff
o Again starts the cycle from step one
FEATURES OF S7-200
Allows Your Program to Immediately Read or Write the IO
Allows Your Program to Interrupt the Scan Cycle
Allows You to Allocate Processing Time for Communications
Tasks
Allows You to Set the States of Digital Outputs for Stop
CHECK
INPUT STATUS
EXECUTE
PROGRAM
UPDATE
OUTPUT STATUS
Mode
Allows You to Define Memory to Be Retained on Loss of Power
Allows You to Filter the Digital Inputs
Allows You to Filter the Analog Inputs
Allows You to Catch Pulses of Short Duration
Provides Password Protection
Provides Analog Adjustment Potentiometers
Provides High-speed IO
TECHNICAL FEATURES OF S7-200
Several models of CPUrsquos
o CPU 221 6in4out 2Kw program
o CPU 222 8in6out 2Kw program
o CPU 224 14in10out 4Kw program
o CPU 226 24in16out 4Kw program
Up to 256 digital input-outputs
Up to 32 analog channels
256 timers 256 counters
Built-in EEPROM memory
Real-time clockcalendar
Built-in communications
Password protection
Memory module
Removable input-output connectors
Wide range of expansion modules
o 8 pt input and output
o 4488 amp1616 inout combination
o 4 channel analog in 2 channel analog out
o 4 ch1ch analog inout combination
o 2 channel RTD in
o 4 channel thermocouple in
o PROFIBUS-DP Slave
o AS Interface master
SELECTING THE OPERATING MODE FOR THE S7- 200 CPU
The S7-200 has two modes of operation STOP mode and RUN mode The status LED on the front of the CPU indicates the current mode of operation In STOP mode the S7-200 is not executing the program and you can download a program or the CPU configuration In RUN mode the S7-200 is running the program
1048600 The S7-200 provides a mode switch for changing the mode of operation You can use the mode switch (located under the front access door of the S7-200) to manually select the operating mode setting the mode switch to STOP mode stops the execution of the program setting the mode switch to RUN mode starts the execution of the program and setting the mode switch to TERM (terminal) mode does not change the operating mode
If a power cycle occurs when the mode switch is set to either STOP or TERM the
S7-200 goes automatically to STOP mode when power is restored If a power cycle occurs when the mode switch is set to RUN the S7-200 goes to RUN mode when power is restored
1048600 STEP 7--MicroWIN allows you to change the operating mode of the online S7-200 To enable the software to change the operating mode you must manually set the mode switch on the S7-200 to either TERM or RUN You can use the PLC gt STOP or PLC gt RUN menu commands or the associated buttons on the toolbar to change the operating mode
1048600 You can insert the STOP instruction in your program to change the S7-200 to STOP mode This allows you to halt the execution of your program based on the program logic
ERRORS IN S7-200
Non-Fatal Errors
Non-fatal errors are those indicating problems with the construction of the user program with the execution of an instruction in the user program and with expansion IO modules You can use STEP 7--MicroWIN to view the error codes that were generated by the non-fatal error There are three basic categories of non-fatal errors
Program-compile errorsThe S7-200 compiles the program as it downloads If the S7-200 detects that the program violates a compilation rule the download is aborted and an error code is generated (A program that was already downloaded to the S7-200 would still exist in the EEPROM and would not be lost) After you correct your program you can download it again
IO errorsAt startup the S7-200 reads the IO configuration from each module During normal operation the S7-200 periodically checks the status of each module and compares it against the configuration obtained during startup If the S7-200 detects a difference the S7-200 sets the configuration error bit in the module error register The S7-200 does not read input data from or write output data to that module until the module configuration again matches the one obtained at startupThe module status information is stored in special memory (SM) bits Your program can monitor and evaluate these bits Refer to Appendix D for more information about the SM bits used for reporting IO errors SM50 is the global IO error bit and remains set while an error condition exists on an expansion module
Program execution errorsYour program can create error conditions while being executed These errors can result from improper use of an instruction or from the processing of invalid data by an instruction For example an indirect-address pointer that was valid when the program compiled could be modified during the execution of the program to point to an out-of-range address This is an example of a run-time programming problem SM43 is setupon the occurrence of a run-time programming problem and remains set while the S7-200 is in RUN mode Program execution error information is stored in special memory (SM) bits Your program can monitor and evaluate these bits The S7-200 does not change to STOP mode when it detects a non-fatal error It only logs the event in SM memory and continues with the execution of your program However you can design your program to force the S7-200 to STOP mode when a non-fatal error is detected
Fatal Errors
Fatal errors cause the S7-200 to stop the execution of your program Depending upon the severity of the fatal error it can render the S7-200 incapable of performing any or all functions The objective for handling fatal errors is to bring the S7-200 to a safe state from which the S7-200 can respond to interrogations about the existing error conditions When a fatal error is detected the S7-200 changes to STOP mode turns on the System Fault LED and the STOP LED overrides the output table and turns off the outputsThe S7-200 remains in this condition until the fatal error condition is corrected
Once you have made the changes to correct the fatal error condition use one of the following methods to restart the S7-200 1048600 Turn the power off and then on 1048600 Change the mode switch from RUN or TERM to STOP 1048600 Select the PLC gt Power-Up Reset menu command from STEP 7--MicroWIN
to restart the S7-200This forces the S7-200 to restart and clear any fatal errors
Restarting the S7-200 clears the fatal error condition and performs power-up diagnostic testing to verify that the fatal error has been corrected If another fatal error condition is found the S7-200 again sets the fault LED indicating that an error still exists Otherwise the S7-200 begins normal operation
Some error conditions can render the S7-200 incapable of communication In these cases you cannot view the error code from the S7-200 These types of errors indicate hardware failures that require the S7-200 to be repaired they cannot be fixed by changes to the program or clearing the memory of the S7-200
APPLICATIONS OF S7-200
Conveyer Systems
Elevators
Test Stations
Placement Systems
Woodworking Machinery
Packaging Equipment
Car Wash Automation
Remote Monitoring And Controlling For Water Wastewater
FEATURES OF LADDER DIAGRAMS
The LAD editor displays the program as a graphical representation similar to electrical wiring diagrams
Ladder programs allow the program to emulate the flow of electric current from a power source through a series of logical input conditions that in turn enable logical output conditions
A LAD program includes a left power rail that is energized Contacts that are closed allow energy to flow through them to the next element and contacts that are open block that energy flow
The logic is separated into networks The program is executed one network at a time from left to right and then top to bottom as dictated by the program Figure shows an example of a LAD program
The various instructions are represented by graphic symbols and include three basic forms
Contacts represent logic input conditions such as switches buttons or internal conditions
Coils usually represent logic output results such as lamps motor starters interposing relays or internal output conditions
Boxes represent additional instructions such as timers counters or math instructions Figure Sample LAD Program
Consider these main points when you select the LAD editor 1048600 Ladder logic is easy for beginning programmers to use 1048600 Graphical representation is easy to understand and is popular around the world 1048600 The LAD editor can be used with both the SIMATIC and IEC 1131--3 Instruction sets
1048600 You can always use the STL editor to display a program created with
the SIMATIC LAD editor
COMPONENTS LIST
Cardboard of 4050 sqcm
PLC S7-200
Sensors
LEDS
Buzzers
Motor
Contactors
Power supply
12v DC battery
Connecting wires
PPI Cable
SENSORS
A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact A proximity sensor often emits an electromagnetic or electrostatic field or a beam of electromagnetic radiation (infrared for instance) and looks for changes in the field or return signal The object being sensed is often referred to as the proximity sensors target Different
proximity sensor targets demand different sensors For example a capacitive or photoelectric sensor might be suitable for a plastic target an inductive proximity sensor requires a metal target
The maximum distance that this sensor can detect is defined nominal range Some sensors have adjustments of the nominal range or means to report a graduated detection distance
Proximity sensors can have a high reliability and long functional life because of the absence of mechanical parts and lack of physical contact between sensor and the sensed object
IEC 60947-5-2 defines the technical details of proximity sensors
A proximity sensor adjusted to a very short range is often used as a touch switch
Applications
Car bumpers that sense distance to nearby cars for parking
Ground proximity warning system for aviation safety Vibration Position measurements of rotating shafts in
machinery Sheet break sensing in paper machine Anti-aircraft artillery
LEDS
Example Circuit symbol
FunctionLEDs emit light when an electric current passes through them
Testing an LED
Never connect an LED directly to a battery or power supply
LEDs must have a resistor in series to limit the current to a safe value for quick testing purposes a 1k resistor is suitable for most LEDs if your supply voltage is 12V or less Remember to connect the LED the correct way round
Sizes Shapes and Viewing angles of LEDs
LEDs are available in a wide variety of sizes and shapes The standard LED has a round cross-section of 5mm diameter and this is probably the best type for general use but 3mm round LEDs are also popular
Round cross-section LEDs are frequently used and they are very easy to install on boxes by drilling a hole of the LED diameter adding a spot of glue will help to hold the LED if necessary LED clips are also available to secure LEDs in holes Other cross-section shapes include square rectangular and triangular
As well as a variety of colours sizes and shapes LEDs also vary in their viewing angle This tells you how much the beam of light spreads out Standard LEDs have a viewing angle of 60deg but others have a narrow beam of 30deg or less
Calculating an LED resistor value
An LED must have a resistor connected in series to limit the current through the LED otherwise it will burn out almost instantly
The resistor value R is given by
R = (VS - VL) I
VS = supply voltage VL = LED voltage (usually 2V but 4V for blue and white LEDs) I = LED current (eg 20mA) this must be less than the maximum permitted
If the calculated value is not available choose the nearest standard resistor value which is greater so that the current will be a little less than you chose In fact you may wish to choose a greater resistor value to reduce the current (to increase battery life for example) but this will make the LED less bright
Working out the LED resistor formula using Ohms law
Ohms law says that the resistance of the resistor R = VI where V = voltage across the resistor (= VS - VL in this case) I = the current through the resistor
So R = (VS - VL) I
BUZZERS
A buzzer or beeper (BUZZERS) is a signalling device usually electronic typically used in automobiles household appliances such as a microwave oven or game shows It most commonly consists of a number of switches or sensors connected to a control unit that determines if and which button was pushed or a preset time has lapsed and usually illuminates a light on the appropriate button or control panel and sounds a warning in the form of a continuous or intermittent buzzing
or beeping sound Initially this device was based on an electromechanical system which was identical to an electric bell without the metal gong (which makes the ringing noise) Often these units were anchored to a wall or ceiling and used the ceiling or wall as a sounding board Another implementation with some AC-connected devices was to implement a circuit to make the AC current into a noise loud enough to drive a loudspeaker and hook this circuit up to a cheap 8-ohm speaker Nowadays it is more popular to use a ceramic-based piezoelectric sounder which makes a high-pitched tone Usually these were hooked up to driver circuits which varied the pitch of the sound or pulsed the sound on and off
The word buzzer comes from the rasping noise that buzzers made when they were electromechanical devices operated from stepped-down AC line voltage at 50 or 60 cycles Other sounds commonly used to indicate that a button has been pressed are a ring or a beep
MOTORS
An electric motor is a device using electrical energy to produce mechanical energy nearly always by the interaction of magnetic fields and current-carrying conductors The reverse process that of using mechanical energy to produce electrical energy is accomplished by a generator or dynamo Traction motors used on vehicles often perform both tasks
Electric motors are found in myriad uses such as industrial fans blowers and pumps machine tools household appliances power tools and computer disk drives among
many other applications Electric motors may be operated by direct current from a battery in a portable device or motor vehicle or from alternating current from a central electrical distribution grid The smallest motors may be found in electric wristwatches Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses The very largest electric motors are used for propulsion of large ships and for such purposes as pipeline compressors with ratings in the thousands of kilowatts Electric motors may be classified by the source of electric power by their internal construction and by application
The physical principle of production of mechanical force by the interaction of an electric current and a magnetic field was known as early as 1821 Electric motors of increasing efficiency were constructed throughout the 19th century but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks
CONNECTORS
A DC connector is an electrical connector for
supplying direct current (DC) power DC connectors
are poorly standardized compared to domestic AC
power plugs and sockets DC plug is a common name
used for one common type of cylindrical two-conductor
plug available in a range of sizes and used to power
small pieces of electronic equipment It is also used to
describe some older multi-pin plugs
Several competing standards exist for DC plugs and in some cases incompatible plugs
will fit together to avoid damaging equipment these conditions must be true
Voltage must match
Polarity is correct
Current ratings are sufficient
Power supply filtering and stability is adequate
for the equipment being powered
Non-matching connectors are forced together
12V DC BATTERY
Features
Less than a 12 volt self discharge per 6 months 4 ea 12Vdc outputs 20 AmpHours Built-charger Digital Voltmeter
Description
This unit supplies a full 12Vdc at 20 AmpHours Designed for the officer that needs a power source that can be charged from 115Ac source or on the way to a incident from the car
The battery source has a very low self discharge rate which makes it perfect for law enforcement use The battery can set on the shelf for more than 6 months without recharging
Everyone knows when you grab a battery operated device the internal battery always requires several hours of charging before using The new voltage indicator reads out voltage to one hundredth of a volt for accurate operation The four outputs are 21mm plug Quick terminals and Cigarette lighter jack amp PT02 (Mil Spec) This model also allows powering
12Vdc sources while plugged in to 115Vac ldquoIts a UPSrdquo
SPECIFICATIONS OF COMPONENTS USED
PLC S7-200
INPUT POWER 230V AC 50 Hz
INPUTS 24 DC INPUTS
OUTPUTS 16 DC OUTPUTS
PROGRAM MEMORY 24
DATA MEMORY 10KB
EXPANSION MODULES 7
COMMUNICATION PORTS 2 RS 485
DIGITAL IO IMAGE SIZE 256(128 in 128 out)
EXECUTION SPEED 022microsecondsinstruction
SENSORS
SENSING RANGE 3mm
HOUSING MATERIAL Brass Nickel Plated
OPERATING VOLTAGE 10-30V
OPERATING CURRENT lt200mA
CONNECTION TYPE Cable
LEDS
DIAMETER 5mm
MAXIMUM VOLTAGE 1V
MAXIMUM CURRENT 10mA
INTENSITY
BUZZERS
OPERATING VOLTAGE30Vp-p
RATED FREQUENCY2000Hz 500Hz
OPERATING TEMP RANGE -20 to 60 degree
SOUND OUTPUT70 dB min10 cm
MOTOR
TOTAL LENGTH 46mm MOTOR DIAMETER 36mm MOTOR LENGTH 25mm DC SUPPLY 4 to 12V RPM 100 BRUSH TYPE Precious metal GEAR HEAD DIAMETER 37mm GEAR HEAD LENGTH 21mm OUTPUT SHAFT Centered SHAFT DIAMETER 4mm and 6mm
SHAFT LENGTH 22mm
- Block diagram of plc
- Applications
-
- Function
- Testing an LED
- Sizes Shapes and Viewing angles of LEDs
- Calculating an LED resistor value
-
- Working out the LED resistor formula using Ohms law
-
Example for a temperature input of 0 to 100 degrees C
For 8 bit resolution the value in the PLC is 0 to 255
For 12 bit resolution the value in the PLC is 0 to 4095
For 16 bit resolution the value in the PLC is 0 to 32768
SPECIAL MODULES
RF ID
Modem modules
Load Cell
Stepper Modules
Temperature Sensor
High Speed Counters
Position Control Cards
Field Bus Cards
o Device Net Profibus Ethernet etc
ELEMENTS OF INPUTS
Digital Inputs
push button
limit switches
Sensors
o Proximity Sensors
o Photo Sensors
Micro Switches
Toggle Switches
Analog Inputs
Pressure Transmitters
Flow Transmitter
Level Transmitter
Thermo Couples
Load Cell
ELEMENTS OF OUTPUTS
Digital Outputs
Relays
Contactors
Indication Lamps
Valves
Analog Outputs
Flow Control Valves
Pressure Control Valves
Drive Inputs
BASIC ELEMENTS OF A PROGRAM
A program block is composed of executable code and comments The executable codes consist of a main program and any subroutines or interrupt routines The code is compiled and downloaded to the S7-200 the program comments are not You can use the organizational elements (main program subroutines and interrupt routines) to structure your control program
Main ProgramThe main body of the program contains the instructions that control your application The S7-200 executes these instructions sequentially once per scan cycle The main program is also referred to as OB1
SubroutinesThese optional elements of your program are executed only when called by the main program by an interrupt routine or by another subroutine Subroutines are useful in cases where you want to execute a function repeatedly Rather than rewriting the logic for each place in the main program where you want the function to occur you can write the logic once in a subroutine and call the subroutine as many times as needed during the main program Subroutines provide several benefits
1048600 Using subroutines reduces the overall size of your program 1048600 Using subroutines decreases your scan time because you have moved the code out of the main program The S7-200 evaluates the code in the main program every scan cycle whether the code is executed or not but the S7-200 evaluates the code in the subroutine only when you call the subroutine and does not evaluate the code during the scans in which the subroutine is not called 1048600 Using subroutines creates code that is portable You can isolate the code for a function in a subroutine and then copy that subroutine into other programs with Interrupt RoutinesThese optional elements of your program react to specific interrupt events You design an interrupt routine to handle a pre-defined interrupt event Whenever the specified event occurs the S7-200 executes the interrupt routineThe interrupt routines are not called by your main program You associate an interrupt routine with an interrupt event and the S7-200 executes the instructions in the interrupt routine only on each occurrence of the interrupt event Other Elements of the ProgramOther blocks contain information for the S7-200 You can choose to download these blocks when you download your programSystem BlockThe system block allows you to configure different hardware options for the S7-200Data BlockThe data block stores the values for different variables (V memory) used by your program You can use the data block to enter initial values for the data
PROGRAMMING LANGUAGES IN PLC
IL (Instruction List) ndash mnemonic programming
LD (Ladder Diagram) ndash Relay logic
ST (Structured Text) ndash A C like programming language
FDB (Functional Block Diagram) ndash Graphical dataflow programming language
SFC (Sequential Flow Chart) ndash Graphical method for structured programs
Basic PLC Memory
Memory on a PLC is separated into 3 main areas
LOAD Memory
Can be RAM (dynamic) or EEPROM (retentive)
Used to store user programs
WORK Memory
Memory is RAM
When PLC starts Program is copied from LOAD memory to
WORK memory The program is then executed from Work
memory
SYSTEM Memory
Memory is RAM
Is used by micro-controller to implement counters timers interrupt
stacks etc
Contains a bit for each D I0
Contains ldquoMarker Memoryrdquo Marker memory is a free area of RAM
that can be used by the programmer
Contains ldquoProcess Input and Output Imagesrdquo Periodically the PLC
will store the states of the inputs to the Process Input Image and
Process Output Image to the output
SELECTION OF A PLC
Selection of PLC Based on
No of Inputs amp Outputs
Input Voltage
Memory
Scan Time
Special IO modules
Expansion Capabilities
Stand alone or Networked
Communication Capabilities
HOW PLC WORKS
Step 1-CHECKING INPUT STATUS
o PLC Scans each input
o Records the data in work memory
Step 2-EXECUTE PROGRAM
o PLC goes through the program logic step by step
o PLC executes the program depending on input status
o Write the output image in work memory
Step 3-UPDATE OUTPUT STATUS
o Changes the statues of the output onoff
o Again starts the cycle from step one
FEATURES OF S7-200
Allows Your Program to Immediately Read or Write the IO
Allows Your Program to Interrupt the Scan Cycle
Allows You to Allocate Processing Time for Communications
Tasks
Allows You to Set the States of Digital Outputs for Stop
CHECK
INPUT STATUS
EXECUTE
PROGRAM
UPDATE
OUTPUT STATUS
Mode
Allows You to Define Memory to Be Retained on Loss of Power
Allows You to Filter the Digital Inputs
Allows You to Filter the Analog Inputs
Allows You to Catch Pulses of Short Duration
Provides Password Protection
Provides Analog Adjustment Potentiometers
Provides High-speed IO
TECHNICAL FEATURES OF S7-200
Several models of CPUrsquos
o CPU 221 6in4out 2Kw program
o CPU 222 8in6out 2Kw program
o CPU 224 14in10out 4Kw program
o CPU 226 24in16out 4Kw program
Up to 256 digital input-outputs
Up to 32 analog channels
256 timers 256 counters
Built-in EEPROM memory
Real-time clockcalendar
Built-in communications
Password protection
Memory module
Removable input-output connectors
Wide range of expansion modules
o 8 pt input and output
o 4488 amp1616 inout combination
o 4 channel analog in 2 channel analog out
o 4 ch1ch analog inout combination
o 2 channel RTD in
o 4 channel thermocouple in
o PROFIBUS-DP Slave
o AS Interface master
SELECTING THE OPERATING MODE FOR THE S7- 200 CPU
The S7-200 has two modes of operation STOP mode and RUN mode The status LED on the front of the CPU indicates the current mode of operation In STOP mode the S7-200 is not executing the program and you can download a program or the CPU configuration In RUN mode the S7-200 is running the program
1048600 The S7-200 provides a mode switch for changing the mode of operation You can use the mode switch (located under the front access door of the S7-200) to manually select the operating mode setting the mode switch to STOP mode stops the execution of the program setting the mode switch to RUN mode starts the execution of the program and setting the mode switch to TERM (terminal) mode does not change the operating mode
If a power cycle occurs when the mode switch is set to either STOP or TERM the
S7-200 goes automatically to STOP mode when power is restored If a power cycle occurs when the mode switch is set to RUN the S7-200 goes to RUN mode when power is restored
1048600 STEP 7--MicroWIN allows you to change the operating mode of the online S7-200 To enable the software to change the operating mode you must manually set the mode switch on the S7-200 to either TERM or RUN You can use the PLC gt STOP or PLC gt RUN menu commands or the associated buttons on the toolbar to change the operating mode
1048600 You can insert the STOP instruction in your program to change the S7-200 to STOP mode This allows you to halt the execution of your program based on the program logic
ERRORS IN S7-200
Non-Fatal Errors
Non-fatal errors are those indicating problems with the construction of the user program with the execution of an instruction in the user program and with expansion IO modules You can use STEP 7--MicroWIN to view the error codes that were generated by the non-fatal error There are three basic categories of non-fatal errors
Program-compile errorsThe S7-200 compiles the program as it downloads If the S7-200 detects that the program violates a compilation rule the download is aborted and an error code is generated (A program that was already downloaded to the S7-200 would still exist in the EEPROM and would not be lost) After you correct your program you can download it again
IO errorsAt startup the S7-200 reads the IO configuration from each module During normal operation the S7-200 periodically checks the status of each module and compares it against the configuration obtained during startup If the S7-200 detects a difference the S7-200 sets the configuration error bit in the module error register The S7-200 does not read input data from or write output data to that module until the module configuration again matches the one obtained at startupThe module status information is stored in special memory (SM) bits Your program can monitor and evaluate these bits Refer to Appendix D for more information about the SM bits used for reporting IO errors SM50 is the global IO error bit and remains set while an error condition exists on an expansion module
Program execution errorsYour program can create error conditions while being executed These errors can result from improper use of an instruction or from the processing of invalid data by an instruction For example an indirect-address pointer that was valid when the program compiled could be modified during the execution of the program to point to an out-of-range address This is an example of a run-time programming problem SM43 is setupon the occurrence of a run-time programming problem and remains set while the S7-200 is in RUN mode Program execution error information is stored in special memory (SM) bits Your program can monitor and evaluate these bits The S7-200 does not change to STOP mode when it detects a non-fatal error It only logs the event in SM memory and continues with the execution of your program However you can design your program to force the S7-200 to STOP mode when a non-fatal error is detected
Fatal Errors
Fatal errors cause the S7-200 to stop the execution of your program Depending upon the severity of the fatal error it can render the S7-200 incapable of performing any or all functions The objective for handling fatal errors is to bring the S7-200 to a safe state from which the S7-200 can respond to interrogations about the existing error conditions When a fatal error is detected the S7-200 changes to STOP mode turns on the System Fault LED and the STOP LED overrides the output table and turns off the outputsThe S7-200 remains in this condition until the fatal error condition is corrected
Once you have made the changes to correct the fatal error condition use one of the following methods to restart the S7-200 1048600 Turn the power off and then on 1048600 Change the mode switch from RUN or TERM to STOP 1048600 Select the PLC gt Power-Up Reset menu command from STEP 7--MicroWIN
to restart the S7-200This forces the S7-200 to restart and clear any fatal errors
Restarting the S7-200 clears the fatal error condition and performs power-up diagnostic testing to verify that the fatal error has been corrected If another fatal error condition is found the S7-200 again sets the fault LED indicating that an error still exists Otherwise the S7-200 begins normal operation
Some error conditions can render the S7-200 incapable of communication In these cases you cannot view the error code from the S7-200 These types of errors indicate hardware failures that require the S7-200 to be repaired they cannot be fixed by changes to the program or clearing the memory of the S7-200
APPLICATIONS OF S7-200
Conveyer Systems
Elevators
Test Stations
Placement Systems
Woodworking Machinery
Packaging Equipment
Car Wash Automation
Remote Monitoring And Controlling For Water Wastewater
FEATURES OF LADDER DIAGRAMS
The LAD editor displays the program as a graphical representation similar to electrical wiring diagrams
Ladder programs allow the program to emulate the flow of electric current from a power source through a series of logical input conditions that in turn enable logical output conditions
A LAD program includes a left power rail that is energized Contacts that are closed allow energy to flow through them to the next element and contacts that are open block that energy flow
The logic is separated into networks The program is executed one network at a time from left to right and then top to bottom as dictated by the program Figure shows an example of a LAD program
The various instructions are represented by graphic symbols and include three basic forms
Contacts represent logic input conditions such as switches buttons or internal conditions
Coils usually represent logic output results such as lamps motor starters interposing relays or internal output conditions
Boxes represent additional instructions such as timers counters or math instructions Figure Sample LAD Program
Consider these main points when you select the LAD editor 1048600 Ladder logic is easy for beginning programmers to use 1048600 Graphical representation is easy to understand and is popular around the world 1048600 The LAD editor can be used with both the SIMATIC and IEC 1131--3 Instruction sets
1048600 You can always use the STL editor to display a program created with
the SIMATIC LAD editor
COMPONENTS LIST
Cardboard of 4050 sqcm
PLC S7-200
Sensors
LEDS
Buzzers
Motor
Contactors
Power supply
12v DC battery
Connecting wires
PPI Cable
SENSORS
A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact A proximity sensor often emits an electromagnetic or electrostatic field or a beam of electromagnetic radiation (infrared for instance) and looks for changes in the field or return signal The object being sensed is often referred to as the proximity sensors target Different
proximity sensor targets demand different sensors For example a capacitive or photoelectric sensor might be suitable for a plastic target an inductive proximity sensor requires a metal target
The maximum distance that this sensor can detect is defined nominal range Some sensors have adjustments of the nominal range or means to report a graduated detection distance
Proximity sensors can have a high reliability and long functional life because of the absence of mechanical parts and lack of physical contact between sensor and the sensed object
IEC 60947-5-2 defines the technical details of proximity sensors
A proximity sensor adjusted to a very short range is often used as a touch switch
Applications
Car bumpers that sense distance to nearby cars for parking
Ground proximity warning system for aviation safety Vibration Position measurements of rotating shafts in
machinery Sheet break sensing in paper machine Anti-aircraft artillery
LEDS
Example Circuit symbol
FunctionLEDs emit light when an electric current passes through them
Testing an LED
Never connect an LED directly to a battery or power supply
LEDs must have a resistor in series to limit the current to a safe value for quick testing purposes a 1k resistor is suitable for most LEDs if your supply voltage is 12V or less Remember to connect the LED the correct way round
Sizes Shapes and Viewing angles of LEDs
LEDs are available in a wide variety of sizes and shapes The standard LED has a round cross-section of 5mm diameter and this is probably the best type for general use but 3mm round LEDs are also popular
Round cross-section LEDs are frequently used and they are very easy to install on boxes by drilling a hole of the LED diameter adding a spot of glue will help to hold the LED if necessary LED clips are also available to secure LEDs in holes Other cross-section shapes include square rectangular and triangular
As well as a variety of colours sizes and shapes LEDs also vary in their viewing angle This tells you how much the beam of light spreads out Standard LEDs have a viewing angle of 60deg but others have a narrow beam of 30deg or less
Calculating an LED resistor value
An LED must have a resistor connected in series to limit the current through the LED otherwise it will burn out almost instantly
The resistor value R is given by
R = (VS - VL) I
VS = supply voltage VL = LED voltage (usually 2V but 4V for blue and white LEDs) I = LED current (eg 20mA) this must be less than the maximum permitted
If the calculated value is not available choose the nearest standard resistor value which is greater so that the current will be a little less than you chose In fact you may wish to choose a greater resistor value to reduce the current (to increase battery life for example) but this will make the LED less bright
Working out the LED resistor formula using Ohms law
Ohms law says that the resistance of the resistor R = VI where V = voltage across the resistor (= VS - VL in this case) I = the current through the resistor
So R = (VS - VL) I
BUZZERS
A buzzer or beeper (BUZZERS) is a signalling device usually electronic typically used in automobiles household appliances such as a microwave oven or game shows It most commonly consists of a number of switches or sensors connected to a control unit that determines if and which button was pushed or a preset time has lapsed and usually illuminates a light on the appropriate button or control panel and sounds a warning in the form of a continuous or intermittent buzzing
or beeping sound Initially this device was based on an electromechanical system which was identical to an electric bell without the metal gong (which makes the ringing noise) Often these units were anchored to a wall or ceiling and used the ceiling or wall as a sounding board Another implementation with some AC-connected devices was to implement a circuit to make the AC current into a noise loud enough to drive a loudspeaker and hook this circuit up to a cheap 8-ohm speaker Nowadays it is more popular to use a ceramic-based piezoelectric sounder which makes a high-pitched tone Usually these were hooked up to driver circuits which varied the pitch of the sound or pulsed the sound on and off
The word buzzer comes from the rasping noise that buzzers made when they were electromechanical devices operated from stepped-down AC line voltage at 50 or 60 cycles Other sounds commonly used to indicate that a button has been pressed are a ring or a beep
MOTORS
An electric motor is a device using electrical energy to produce mechanical energy nearly always by the interaction of magnetic fields and current-carrying conductors The reverse process that of using mechanical energy to produce electrical energy is accomplished by a generator or dynamo Traction motors used on vehicles often perform both tasks
Electric motors are found in myriad uses such as industrial fans blowers and pumps machine tools household appliances power tools and computer disk drives among
many other applications Electric motors may be operated by direct current from a battery in a portable device or motor vehicle or from alternating current from a central electrical distribution grid The smallest motors may be found in electric wristwatches Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses The very largest electric motors are used for propulsion of large ships and for such purposes as pipeline compressors with ratings in the thousands of kilowatts Electric motors may be classified by the source of electric power by their internal construction and by application
The physical principle of production of mechanical force by the interaction of an electric current and a magnetic field was known as early as 1821 Electric motors of increasing efficiency were constructed throughout the 19th century but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks
CONNECTORS
A DC connector is an electrical connector for
supplying direct current (DC) power DC connectors
are poorly standardized compared to domestic AC
power plugs and sockets DC plug is a common name
used for one common type of cylindrical two-conductor
plug available in a range of sizes and used to power
small pieces of electronic equipment It is also used to
describe some older multi-pin plugs
Several competing standards exist for DC plugs and in some cases incompatible plugs
will fit together to avoid damaging equipment these conditions must be true
Voltage must match
Polarity is correct
Current ratings are sufficient
Power supply filtering and stability is adequate
for the equipment being powered
Non-matching connectors are forced together
12V DC BATTERY
Features
Less than a 12 volt self discharge per 6 months 4 ea 12Vdc outputs 20 AmpHours Built-charger Digital Voltmeter
Description
This unit supplies a full 12Vdc at 20 AmpHours Designed for the officer that needs a power source that can be charged from 115Ac source or on the way to a incident from the car
The battery source has a very low self discharge rate which makes it perfect for law enforcement use The battery can set on the shelf for more than 6 months without recharging
Everyone knows when you grab a battery operated device the internal battery always requires several hours of charging before using The new voltage indicator reads out voltage to one hundredth of a volt for accurate operation The four outputs are 21mm plug Quick terminals and Cigarette lighter jack amp PT02 (Mil Spec) This model also allows powering
12Vdc sources while plugged in to 115Vac ldquoIts a UPSrdquo
SPECIFICATIONS OF COMPONENTS USED
PLC S7-200
INPUT POWER 230V AC 50 Hz
INPUTS 24 DC INPUTS
OUTPUTS 16 DC OUTPUTS
PROGRAM MEMORY 24
DATA MEMORY 10KB
EXPANSION MODULES 7
COMMUNICATION PORTS 2 RS 485
DIGITAL IO IMAGE SIZE 256(128 in 128 out)
EXECUTION SPEED 022microsecondsinstruction
SENSORS
SENSING RANGE 3mm
HOUSING MATERIAL Brass Nickel Plated
OPERATING VOLTAGE 10-30V
OPERATING CURRENT lt200mA
CONNECTION TYPE Cable
LEDS
DIAMETER 5mm
MAXIMUM VOLTAGE 1V
MAXIMUM CURRENT 10mA
INTENSITY
BUZZERS
OPERATING VOLTAGE30Vp-p
RATED FREQUENCY2000Hz 500Hz
OPERATING TEMP RANGE -20 to 60 degree
SOUND OUTPUT70 dB min10 cm
MOTOR
TOTAL LENGTH 46mm MOTOR DIAMETER 36mm MOTOR LENGTH 25mm DC SUPPLY 4 to 12V RPM 100 BRUSH TYPE Precious metal GEAR HEAD DIAMETER 37mm GEAR HEAD LENGTH 21mm OUTPUT SHAFT Centered SHAFT DIAMETER 4mm and 6mm
SHAFT LENGTH 22mm
- Block diagram of plc
- Applications
-
- Function
- Testing an LED
- Sizes Shapes and Viewing angles of LEDs
- Calculating an LED resistor value
-
- Working out the LED resistor formula using Ohms law
-
Toggle Switches
Analog Inputs
Pressure Transmitters
Flow Transmitter
Level Transmitter
Thermo Couples
Load Cell
ELEMENTS OF OUTPUTS
Digital Outputs
Relays
Contactors
Indication Lamps
Valves
Analog Outputs
Flow Control Valves
Pressure Control Valves
Drive Inputs
BASIC ELEMENTS OF A PROGRAM
A program block is composed of executable code and comments The executable codes consist of a main program and any subroutines or interrupt routines The code is compiled and downloaded to the S7-200 the program comments are not You can use the organizational elements (main program subroutines and interrupt routines) to structure your control program
Main ProgramThe main body of the program contains the instructions that control your application The S7-200 executes these instructions sequentially once per scan cycle The main program is also referred to as OB1
SubroutinesThese optional elements of your program are executed only when called by the main program by an interrupt routine or by another subroutine Subroutines are useful in cases where you want to execute a function repeatedly Rather than rewriting the logic for each place in the main program where you want the function to occur you can write the logic once in a subroutine and call the subroutine as many times as needed during the main program Subroutines provide several benefits
1048600 Using subroutines reduces the overall size of your program 1048600 Using subroutines decreases your scan time because you have moved the code out of the main program The S7-200 evaluates the code in the main program every scan cycle whether the code is executed or not but the S7-200 evaluates the code in the subroutine only when you call the subroutine and does not evaluate the code during the scans in which the subroutine is not called 1048600 Using subroutines creates code that is portable You can isolate the code for a function in a subroutine and then copy that subroutine into other programs with Interrupt RoutinesThese optional elements of your program react to specific interrupt events You design an interrupt routine to handle a pre-defined interrupt event Whenever the specified event occurs the S7-200 executes the interrupt routineThe interrupt routines are not called by your main program You associate an interrupt routine with an interrupt event and the S7-200 executes the instructions in the interrupt routine only on each occurrence of the interrupt event Other Elements of the ProgramOther blocks contain information for the S7-200 You can choose to download these blocks when you download your programSystem BlockThe system block allows you to configure different hardware options for the S7-200Data BlockThe data block stores the values for different variables (V memory) used by your program You can use the data block to enter initial values for the data
PROGRAMMING LANGUAGES IN PLC
IL (Instruction List) ndash mnemonic programming
LD (Ladder Diagram) ndash Relay logic
ST (Structured Text) ndash A C like programming language
FDB (Functional Block Diagram) ndash Graphical dataflow programming language
SFC (Sequential Flow Chart) ndash Graphical method for structured programs
Basic PLC Memory
Memory on a PLC is separated into 3 main areas
LOAD Memory
Can be RAM (dynamic) or EEPROM (retentive)
Used to store user programs
WORK Memory
Memory is RAM
When PLC starts Program is copied from LOAD memory to
WORK memory The program is then executed from Work
memory
SYSTEM Memory
Memory is RAM
Is used by micro-controller to implement counters timers interrupt
stacks etc
Contains a bit for each D I0
Contains ldquoMarker Memoryrdquo Marker memory is a free area of RAM
that can be used by the programmer
Contains ldquoProcess Input and Output Imagesrdquo Periodically the PLC
will store the states of the inputs to the Process Input Image and
Process Output Image to the output
SELECTION OF A PLC
Selection of PLC Based on
No of Inputs amp Outputs
Input Voltage
Memory
Scan Time
Special IO modules
Expansion Capabilities
Stand alone or Networked
Communication Capabilities
HOW PLC WORKS
Step 1-CHECKING INPUT STATUS
o PLC Scans each input
o Records the data in work memory
Step 2-EXECUTE PROGRAM
o PLC goes through the program logic step by step
o PLC executes the program depending on input status
o Write the output image in work memory
Step 3-UPDATE OUTPUT STATUS
o Changes the statues of the output onoff
o Again starts the cycle from step one
FEATURES OF S7-200
Allows Your Program to Immediately Read or Write the IO
Allows Your Program to Interrupt the Scan Cycle
Allows You to Allocate Processing Time for Communications
Tasks
Allows You to Set the States of Digital Outputs for Stop
CHECK
INPUT STATUS
EXECUTE
PROGRAM
UPDATE
OUTPUT STATUS
Mode
Allows You to Define Memory to Be Retained on Loss of Power
Allows You to Filter the Digital Inputs
Allows You to Filter the Analog Inputs
Allows You to Catch Pulses of Short Duration
Provides Password Protection
Provides Analog Adjustment Potentiometers
Provides High-speed IO
TECHNICAL FEATURES OF S7-200
Several models of CPUrsquos
o CPU 221 6in4out 2Kw program
o CPU 222 8in6out 2Kw program
o CPU 224 14in10out 4Kw program
o CPU 226 24in16out 4Kw program
Up to 256 digital input-outputs
Up to 32 analog channels
256 timers 256 counters
Built-in EEPROM memory
Real-time clockcalendar
Built-in communications
Password protection
Memory module
Removable input-output connectors
Wide range of expansion modules
o 8 pt input and output
o 4488 amp1616 inout combination
o 4 channel analog in 2 channel analog out
o 4 ch1ch analog inout combination
o 2 channel RTD in
o 4 channel thermocouple in
o PROFIBUS-DP Slave
o AS Interface master
SELECTING THE OPERATING MODE FOR THE S7- 200 CPU
The S7-200 has two modes of operation STOP mode and RUN mode The status LED on the front of the CPU indicates the current mode of operation In STOP mode the S7-200 is not executing the program and you can download a program or the CPU configuration In RUN mode the S7-200 is running the program
1048600 The S7-200 provides a mode switch for changing the mode of operation You can use the mode switch (located under the front access door of the S7-200) to manually select the operating mode setting the mode switch to STOP mode stops the execution of the program setting the mode switch to RUN mode starts the execution of the program and setting the mode switch to TERM (terminal) mode does not change the operating mode
If a power cycle occurs when the mode switch is set to either STOP or TERM the
S7-200 goes automatically to STOP mode when power is restored If a power cycle occurs when the mode switch is set to RUN the S7-200 goes to RUN mode when power is restored
1048600 STEP 7--MicroWIN allows you to change the operating mode of the online S7-200 To enable the software to change the operating mode you must manually set the mode switch on the S7-200 to either TERM or RUN You can use the PLC gt STOP or PLC gt RUN menu commands or the associated buttons on the toolbar to change the operating mode
1048600 You can insert the STOP instruction in your program to change the S7-200 to STOP mode This allows you to halt the execution of your program based on the program logic
ERRORS IN S7-200
Non-Fatal Errors
Non-fatal errors are those indicating problems with the construction of the user program with the execution of an instruction in the user program and with expansion IO modules You can use STEP 7--MicroWIN to view the error codes that were generated by the non-fatal error There are three basic categories of non-fatal errors
Program-compile errorsThe S7-200 compiles the program as it downloads If the S7-200 detects that the program violates a compilation rule the download is aborted and an error code is generated (A program that was already downloaded to the S7-200 would still exist in the EEPROM and would not be lost) After you correct your program you can download it again
IO errorsAt startup the S7-200 reads the IO configuration from each module During normal operation the S7-200 periodically checks the status of each module and compares it against the configuration obtained during startup If the S7-200 detects a difference the S7-200 sets the configuration error bit in the module error register The S7-200 does not read input data from or write output data to that module until the module configuration again matches the one obtained at startupThe module status information is stored in special memory (SM) bits Your program can monitor and evaluate these bits Refer to Appendix D for more information about the SM bits used for reporting IO errors SM50 is the global IO error bit and remains set while an error condition exists on an expansion module
Program execution errorsYour program can create error conditions while being executed These errors can result from improper use of an instruction or from the processing of invalid data by an instruction For example an indirect-address pointer that was valid when the program compiled could be modified during the execution of the program to point to an out-of-range address This is an example of a run-time programming problem SM43 is setupon the occurrence of a run-time programming problem and remains set while the S7-200 is in RUN mode Program execution error information is stored in special memory (SM) bits Your program can monitor and evaluate these bits The S7-200 does not change to STOP mode when it detects a non-fatal error It only logs the event in SM memory and continues with the execution of your program However you can design your program to force the S7-200 to STOP mode when a non-fatal error is detected
Fatal Errors
Fatal errors cause the S7-200 to stop the execution of your program Depending upon the severity of the fatal error it can render the S7-200 incapable of performing any or all functions The objective for handling fatal errors is to bring the S7-200 to a safe state from which the S7-200 can respond to interrogations about the existing error conditions When a fatal error is detected the S7-200 changes to STOP mode turns on the System Fault LED and the STOP LED overrides the output table and turns off the outputsThe S7-200 remains in this condition until the fatal error condition is corrected
Once you have made the changes to correct the fatal error condition use one of the following methods to restart the S7-200 1048600 Turn the power off and then on 1048600 Change the mode switch from RUN or TERM to STOP 1048600 Select the PLC gt Power-Up Reset menu command from STEP 7--MicroWIN
to restart the S7-200This forces the S7-200 to restart and clear any fatal errors
Restarting the S7-200 clears the fatal error condition and performs power-up diagnostic testing to verify that the fatal error has been corrected If another fatal error condition is found the S7-200 again sets the fault LED indicating that an error still exists Otherwise the S7-200 begins normal operation
Some error conditions can render the S7-200 incapable of communication In these cases you cannot view the error code from the S7-200 These types of errors indicate hardware failures that require the S7-200 to be repaired they cannot be fixed by changes to the program or clearing the memory of the S7-200
APPLICATIONS OF S7-200
Conveyer Systems
Elevators
Test Stations
Placement Systems
Woodworking Machinery
Packaging Equipment
Car Wash Automation
Remote Monitoring And Controlling For Water Wastewater
FEATURES OF LADDER DIAGRAMS
The LAD editor displays the program as a graphical representation similar to electrical wiring diagrams
Ladder programs allow the program to emulate the flow of electric current from a power source through a series of logical input conditions that in turn enable logical output conditions
A LAD program includes a left power rail that is energized Contacts that are closed allow energy to flow through them to the next element and contacts that are open block that energy flow
The logic is separated into networks The program is executed one network at a time from left to right and then top to bottom as dictated by the program Figure shows an example of a LAD program
The various instructions are represented by graphic symbols and include three basic forms
Contacts represent logic input conditions such as switches buttons or internal conditions
Coils usually represent logic output results such as lamps motor starters interposing relays or internal output conditions
Boxes represent additional instructions such as timers counters or math instructions Figure Sample LAD Program
Consider these main points when you select the LAD editor 1048600 Ladder logic is easy for beginning programmers to use 1048600 Graphical representation is easy to understand and is popular around the world 1048600 The LAD editor can be used with both the SIMATIC and IEC 1131--3 Instruction sets
1048600 You can always use the STL editor to display a program created with
the SIMATIC LAD editor
COMPONENTS LIST
Cardboard of 4050 sqcm
PLC S7-200
Sensors
LEDS
Buzzers
Motor
Contactors
Power supply
12v DC battery
Connecting wires
PPI Cable
SENSORS
A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact A proximity sensor often emits an electromagnetic or electrostatic field or a beam of electromagnetic radiation (infrared for instance) and looks for changes in the field or return signal The object being sensed is often referred to as the proximity sensors target Different
proximity sensor targets demand different sensors For example a capacitive or photoelectric sensor might be suitable for a plastic target an inductive proximity sensor requires a metal target
The maximum distance that this sensor can detect is defined nominal range Some sensors have adjustments of the nominal range or means to report a graduated detection distance
Proximity sensors can have a high reliability and long functional life because of the absence of mechanical parts and lack of physical contact between sensor and the sensed object
IEC 60947-5-2 defines the technical details of proximity sensors
A proximity sensor adjusted to a very short range is often used as a touch switch
Applications
Car bumpers that sense distance to nearby cars for parking
Ground proximity warning system for aviation safety Vibration Position measurements of rotating shafts in
machinery Sheet break sensing in paper machine Anti-aircraft artillery
LEDS
Example Circuit symbol
FunctionLEDs emit light when an electric current passes through them
Testing an LED
Never connect an LED directly to a battery or power supply
LEDs must have a resistor in series to limit the current to a safe value for quick testing purposes a 1k resistor is suitable for most LEDs if your supply voltage is 12V or less Remember to connect the LED the correct way round
Sizes Shapes and Viewing angles of LEDs
LEDs are available in a wide variety of sizes and shapes The standard LED has a round cross-section of 5mm diameter and this is probably the best type for general use but 3mm round LEDs are also popular
Round cross-section LEDs are frequently used and they are very easy to install on boxes by drilling a hole of the LED diameter adding a spot of glue will help to hold the LED if necessary LED clips are also available to secure LEDs in holes Other cross-section shapes include square rectangular and triangular
As well as a variety of colours sizes and shapes LEDs also vary in their viewing angle This tells you how much the beam of light spreads out Standard LEDs have a viewing angle of 60deg but others have a narrow beam of 30deg or less
Calculating an LED resistor value
An LED must have a resistor connected in series to limit the current through the LED otherwise it will burn out almost instantly
The resistor value R is given by
R = (VS - VL) I
VS = supply voltage VL = LED voltage (usually 2V but 4V for blue and white LEDs) I = LED current (eg 20mA) this must be less than the maximum permitted
If the calculated value is not available choose the nearest standard resistor value which is greater so that the current will be a little less than you chose In fact you may wish to choose a greater resistor value to reduce the current (to increase battery life for example) but this will make the LED less bright
Working out the LED resistor formula using Ohms law
Ohms law says that the resistance of the resistor R = VI where V = voltage across the resistor (= VS - VL in this case) I = the current through the resistor
So R = (VS - VL) I
BUZZERS
A buzzer or beeper (BUZZERS) is a signalling device usually electronic typically used in automobiles household appliances such as a microwave oven or game shows It most commonly consists of a number of switches or sensors connected to a control unit that determines if and which button was pushed or a preset time has lapsed and usually illuminates a light on the appropriate button or control panel and sounds a warning in the form of a continuous or intermittent buzzing
or beeping sound Initially this device was based on an electromechanical system which was identical to an electric bell without the metal gong (which makes the ringing noise) Often these units were anchored to a wall or ceiling and used the ceiling or wall as a sounding board Another implementation with some AC-connected devices was to implement a circuit to make the AC current into a noise loud enough to drive a loudspeaker and hook this circuit up to a cheap 8-ohm speaker Nowadays it is more popular to use a ceramic-based piezoelectric sounder which makes a high-pitched tone Usually these were hooked up to driver circuits which varied the pitch of the sound or pulsed the sound on and off
The word buzzer comes from the rasping noise that buzzers made when they were electromechanical devices operated from stepped-down AC line voltage at 50 or 60 cycles Other sounds commonly used to indicate that a button has been pressed are a ring or a beep
MOTORS
An electric motor is a device using electrical energy to produce mechanical energy nearly always by the interaction of magnetic fields and current-carrying conductors The reverse process that of using mechanical energy to produce electrical energy is accomplished by a generator or dynamo Traction motors used on vehicles often perform both tasks
Electric motors are found in myriad uses such as industrial fans blowers and pumps machine tools household appliances power tools and computer disk drives among
many other applications Electric motors may be operated by direct current from a battery in a portable device or motor vehicle or from alternating current from a central electrical distribution grid The smallest motors may be found in electric wristwatches Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses The very largest electric motors are used for propulsion of large ships and for such purposes as pipeline compressors with ratings in the thousands of kilowatts Electric motors may be classified by the source of electric power by their internal construction and by application
The physical principle of production of mechanical force by the interaction of an electric current and a magnetic field was known as early as 1821 Electric motors of increasing efficiency were constructed throughout the 19th century but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks
CONNECTORS
A DC connector is an electrical connector for
supplying direct current (DC) power DC connectors
are poorly standardized compared to domestic AC
power plugs and sockets DC plug is a common name
used for one common type of cylindrical two-conductor
plug available in a range of sizes and used to power
small pieces of electronic equipment It is also used to
describe some older multi-pin plugs
Several competing standards exist for DC plugs and in some cases incompatible plugs
will fit together to avoid damaging equipment these conditions must be true
Voltage must match
Polarity is correct
Current ratings are sufficient
Power supply filtering and stability is adequate
for the equipment being powered
Non-matching connectors are forced together
12V DC BATTERY
Features
Less than a 12 volt self discharge per 6 months 4 ea 12Vdc outputs 20 AmpHours Built-charger Digital Voltmeter
Description
This unit supplies a full 12Vdc at 20 AmpHours Designed for the officer that needs a power source that can be charged from 115Ac source or on the way to a incident from the car
The battery source has a very low self discharge rate which makes it perfect for law enforcement use The battery can set on the shelf for more than 6 months without recharging
Everyone knows when you grab a battery operated device the internal battery always requires several hours of charging before using The new voltage indicator reads out voltage to one hundredth of a volt for accurate operation The four outputs are 21mm plug Quick terminals and Cigarette lighter jack amp PT02 (Mil Spec) This model also allows powering
12Vdc sources while plugged in to 115Vac ldquoIts a UPSrdquo
SPECIFICATIONS OF COMPONENTS USED
PLC S7-200
INPUT POWER 230V AC 50 Hz
INPUTS 24 DC INPUTS
OUTPUTS 16 DC OUTPUTS
PROGRAM MEMORY 24
DATA MEMORY 10KB
EXPANSION MODULES 7
COMMUNICATION PORTS 2 RS 485
DIGITAL IO IMAGE SIZE 256(128 in 128 out)
EXECUTION SPEED 022microsecondsinstruction
SENSORS
SENSING RANGE 3mm
HOUSING MATERIAL Brass Nickel Plated
OPERATING VOLTAGE 10-30V
OPERATING CURRENT lt200mA
CONNECTION TYPE Cable
LEDS
DIAMETER 5mm
MAXIMUM VOLTAGE 1V
MAXIMUM CURRENT 10mA
INTENSITY
BUZZERS
OPERATING VOLTAGE30Vp-p
RATED FREQUENCY2000Hz 500Hz
OPERATING TEMP RANGE -20 to 60 degree
SOUND OUTPUT70 dB min10 cm
MOTOR
TOTAL LENGTH 46mm MOTOR DIAMETER 36mm MOTOR LENGTH 25mm DC SUPPLY 4 to 12V RPM 100 BRUSH TYPE Precious metal GEAR HEAD DIAMETER 37mm GEAR HEAD LENGTH 21mm OUTPUT SHAFT Centered SHAFT DIAMETER 4mm and 6mm
SHAFT LENGTH 22mm
- Block diagram of plc
- Applications
-
- Function
- Testing an LED
- Sizes Shapes and Viewing angles of LEDs
- Calculating an LED resistor value
-
- Working out the LED resistor formula using Ohms law
-
Flow Control Valves
Pressure Control Valves
Drive Inputs
BASIC ELEMENTS OF A PROGRAM
A program block is composed of executable code and comments The executable codes consist of a main program and any subroutines or interrupt routines The code is compiled and downloaded to the S7-200 the program comments are not You can use the organizational elements (main program subroutines and interrupt routines) to structure your control program
Main ProgramThe main body of the program contains the instructions that control your application The S7-200 executes these instructions sequentially once per scan cycle The main program is also referred to as OB1
SubroutinesThese optional elements of your program are executed only when called by the main program by an interrupt routine or by another subroutine Subroutines are useful in cases where you want to execute a function repeatedly Rather than rewriting the logic for each place in the main program where you want the function to occur you can write the logic once in a subroutine and call the subroutine as many times as needed during the main program Subroutines provide several benefits
1048600 Using subroutines reduces the overall size of your program 1048600 Using subroutines decreases your scan time because you have moved the code out of the main program The S7-200 evaluates the code in the main program every scan cycle whether the code is executed or not but the S7-200 evaluates the code in the subroutine only when you call the subroutine and does not evaluate the code during the scans in which the subroutine is not called 1048600 Using subroutines creates code that is portable You can isolate the code for a function in a subroutine and then copy that subroutine into other programs with Interrupt RoutinesThese optional elements of your program react to specific interrupt events You design an interrupt routine to handle a pre-defined interrupt event Whenever the specified event occurs the S7-200 executes the interrupt routineThe interrupt routines are not called by your main program You associate an interrupt routine with an interrupt event and the S7-200 executes the instructions in the interrupt routine only on each occurrence of the interrupt event Other Elements of the ProgramOther blocks contain information for the S7-200 You can choose to download these blocks when you download your programSystem BlockThe system block allows you to configure different hardware options for the S7-200Data BlockThe data block stores the values for different variables (V memory) used by your program You can use the data block to enter initial values for the data
PROGRAMMING LANGUAGES IN PLC
IL (Instruction List) ndash mnemonic programming
LD (Ladder Diagram) ndash Relay logic
ST (Structured Text) ndash A C like programming language
FDB (Functional Block Diagram) ndash Graphical dataflow programming language
SFC (Sequential Flow Chart) ndash Graphical method for structured programs
Basic PLC Memory
Memory on a PLC is separated into 3 main areas
LOAD Memory
Can be RAM (dynamic) or EEPROM (retentive)
Used to store user programs
WORK Memory
Memory is RAM
When PLC starts Program is copied from LOAD memory to
WORK memory The program is then executed from Work
memory
SYSTEM Memory
Memory is RAM
Is used by micro-controller to implement counters timers interrupt
stacks etc
Contains a bit for each D I0
Contains ldquoMarker Memoryrdquo Marker memory is a free area of RAM
that can be used by the programmer
Contains ldquoProcess Input and Output Imagesrdquo Periodically the PLC
will store the states of the inputs to the Process Input Image and
Process Output Image to the output
SELECTION OF A PLC
Selection of PLC Based on
No of Inputs amp Outputs
Input Voltage
Memory
Scan Time
Special IO modules
Expansion Capabilities
Stand alone or Networked
Communication Capabilities
HOW PLC WORKS
Step 1-CHECKING INPUT STATUS
o PLC Scans each input
o Records the data in work memory
Step 2-EXECUTE PROGRAM
o PLC goes through the program logic step by step
o PLC executes the program depending on input status
o Write the output image in work memory
Step 3-UPDATE OUTPUT STATUS
o Changes the statues of the output onoff
o Again starts the cycle from step one
FEATURES OF S7-200
Allows Your Program to Immediately Read or Write the IO
Allows Your Program to Interrupt the Scan Cycle
Allows You to Allocate Processing Time for Communications
Tasks
Allows You to Set the States of Digital Outputs for Stop
CHECK
INPUT STATUS
EXECUTE
PROGRAM
UPDATE
OUTPUT STATUS
Mode
Allows You to Define Memory to Be Retained on Loss of Power
Allows You to Filter the Digital Inputs
Allows You to Filter the Analog Inputs
Allows You to Catch Pulses of Short Duration
Provides Password Protection
Provides Analog Adjustment Potentiometers
Provides High-speed IO
TECHNICAL FEATURES OF S7-200
Several models of CPUrsquos
o CPU 221 6in4out 2Kw program
o CPU 222 8in6out 2Kw program
o CPU 224 14in10out 4Kw program
o CPU 226 24in16out 4Kw program
Up to 256 digital input-outputs
Up to 32 analog channels
256 timers 256 counters
Built-in EEPROM memory
Real-time clockcalendar
Built-in communications
Password protection
Memory module
Removable input-output connectors
Wide range of expansion modules
o 8 pt input and output
o 4488 amp1616 inout combination
o 4 channel analog in 2 channel analog out
o 4 ch1ch analog inout combination
o 2 channel RTD in
o 4 channel thermocouple in
o PROFIBUS-DP Slave
o AS Interface master
SELECTING THE OPERATING MODE FOR THE S7- 200 CPU
The S7-200 has two modes of operation STOP mode and RUN mode The status LED on the front of the CPU indicates the current mode of operation In STOP mode the S7-200 is not executing the program and you can download a program or the CPU configuration In RUN mode the S7-200 is running the program
1048600 The S7-200 provides a mode switch for changing the mode of operation You can use the mode switch (located under the front access door of the S7-200) to manually select the operating mode setting the mode switch to STOP mode stops the execution of the program setting the mode switch to RUN mode starts the execution of the program and setting the mode switch to TERM (terminal) mode does not change the operating mode
If a power cycle occurs when the mode switch is set to either STOP or TERM the
S7-200 goes automatically to STOP mode when power is restored If a power cycle occurs when the mode switch is set to RUN the S7-200 goes to RUN mode when power is restored
1048600 STEP 7--MicroWIN allows you to change the operating mode of the online S7-200 To enable the software to change the operating mode you must manually set the mode switch on the S7-200 to either TERM or RUN You can use the PLC gt STOP or PLC gt RUN menu commands or the associated buttons on the toolbar to change the operating mode
1048600 You can insert the STOP instruction in your program to change the S7-200 to STOP mode This allows you to halt the execution of your program based on the program logic
ERRORS IN S7-200
Non-Fatal Errors
Non-fatal errors are those indicating problems with the construction of the user program with the execution of an instruction in the user program and with expansion IO modules You can use STEP 7--MicroWIN to view the error codes that were generated by the non-fatal error There are three basic categories of non-fatal errors
Program-compile errorsThe S7-200 compiles the program as it downloads If the S7-200 detects that the program violates a compilation rule the download is aborted and an error code is generated (A program that was already downloaded to the S7-200 would still exist in the EEPROM and would not be lost) After you correct your program you can download it again
IO errorsAt startup the S7-200 reads the IO configuration from each module During normal operation the S7-200 periodically checks the status of each module and compares it against the configuration obtained during startup If the S7-200 detects a difference the S7-200 sets the configuration error bit in the module error register The S7-200 does not read input data from or write output data to that module until the module configuration again matches the one obtained at startupThe module status information is stored in special memory (SM) bits Your program can monitor and evaluate these bits Refer to Appendix D for more information about the SM bits used for reporting IO errors SM50 is the global IO error bit and remains set while an error condition exists on an expansion module
Program execution errorsYour program can create error conditions while being executed These errors can result from improper use of an instruction or from the processing of invalid data by an instruction For example an indirect-address pointer that was valid when the program compiled could be modified during the execution of the program to point to an out-of-range address This is an example of a run-time programming problem SM43 is setupon the occurrence of a run-time programming problem and remains set while the S7-200 is in RUN mode Program execution error information is stored in special memory (SM) bits Your program can monitor and evaluate these bits The S7-200 does not change to STOP mode when it detects a non-fatal error It only logs the event in SM memory and continues with the execution of your program However you can design your program to force the S7-200 to STOP mode when a non-fatal error is detected
Fatal Errors
Fatal errors cause the S7-200 to stop the execution of your program Depending upon the severity of the fatal error it can render the S7-200 incapable of performing any or all functions The objective for handling fatal errors is to bring the S7-200 to a safe state from which the S7-200 can respond to interrogations about the existing error conditions When a fatal error is detected the S7-200 changes to STOP mode turns on the System Fault LED and the STOP LED overrides the output table and turns off the outputsThe S7-200 remains in this condition until the fatal error condition is corrected
Once you have made the changes to correct the fatal error condition use one of the following methods to restart the S7-200 1048600 Turn the power off and then on 1048600 Change the mode switch from RUN or TERM to STOP 1048600 Select the PLC gt Power-Up Reset menu command from STEP 7--MicroWIN
to restart the S7-200This forces the S7-200 to restart and clear any fatal errors
Restarting the S7-200 clears the fatal error condition and performs power-up diagnostic testing to verify that the fatal error has been corrected If another fatal error condition is found the S7-200 again sets the fault LED indicating that an error still exists Otherwise the S7-200 begins normal operation
Some error conditions can render the S7-200 incapable of communication In these cases you cannot view the error code from the S7-200 These types of errors indicate hardware failures that require the S7-200 to be repaired they cannot be fixed by changes to the program or clearing the memory of the S7-200
APPLICATIONS OF S7-200
Conveyer Systems
Elevators
Test Stations
Placement Systems
Woodworking Machinery
Packaging Equipment
Car Wash Automation
Remote Monitoring And Controlling For Water Wastewater
FEATURES OF LADDER DIAGRAMS
The LAD editor displays the program as a graphical representation similar to electrical wiring diagrams
Ladder programs allow the program to emulate the flow of electric current from a power source through a series of logical input conditions that in turn enable logical output conditions
A LAD program includes a left power rail that is energized Contacts that are closed allow energy to flow through them to the next element and contacts that are open block that energy flow
The logic is separated into networks The program is executed one network at a time from left to right and then top to bottom as dictated by the program Figure shows an example of a LAD program
The various instructions are represented by graphic symbols and include three basic forms
Contacts represent logic input conditions such as switches buttons or internal conditions
Coils usually represent logic output results such as lamps motor starters interposing relays or internal output conditions
Boxes represent additional instructions such as timers counters or math instructions Figure Sample LAD Program
Consider these main points when you select the LAD editor 1048600 Ladder logic is easy for beginning programmers to use 1048600 Graphical representation is easy to understand and is popular around the world 1048600 The LAD editor can be used with both the SIMATIC and IEC 1131--3 Instruction sets
1048600 You can always use the STL editor to display a program created with
the SIMATIC LAD editor
COMPONENTS LIST
Cardboard of 4050 sqcm
PLC S7-200
Sensors
LEDS
Buzzers
Motor
Contactors
Power supply
12v DC battery
Connecting wires
PPI Cable
SENSORS
A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact A proximity sensor often emits an electromagnetic or electrostatic field or a beam of electromagnetic radiation (infrared for instance) and looks for changes in the field or return signal The object being sensed is often referred to as the proximity sensors target Different
proximity sensor targets demand different sensors For example a capacitive or photoelectric sensor might be suitable for a plastic target an inductive proximity sensor requires a metal target
The maximum distance that this sensor can detect is defined nominal range Some sensors have adjustments of the nominal range or means to report a graduated detection distance
Proximity sensors can have a high reliability and long functional life because of the absence of mechanical parts and lack of physical contact between sensor and the sensed object
IEC 60947-5-2 defines the technical details of proximity sensors
A proximity sensor adjusted to a very short range is often used as a touch switch
Applications
Car bumpers that sense distance to nearby cars for parking
Ground proximity warning system for aviation safety Vibration Position measurements of rotating shafts in
machinery Sheet break sensing in paper machine Anti-aircraft artillery
LEDS
Example Circuit symbol
FunctionLEDs emit light when an electric current passes through them
Testing an LED
Never connect an LED directly to a battery or power supply
LEDs must have a resistor in series to limit the current to a safe value for quick testing purposes a 1k resistor is suitable for most LEDs if your supply voltage is 12V or less Remember to connect the LED the correct way round
Sizes Shapes and Viewing angles of LEDs
LEDs are available in a wide variety of sizes and shapes The standard LED has a round cross-section of 5mm diameter and this is probably the best type for general use but 3mm round LEDs are also popular
Round cross-section LEDs are frequently used and they are very easy to install on boxes by drilling a hole of the LED diameter adding a spot of glue will help to hold the LED if necessary LED clips are also available to secure LEDs in holes Other cross-section shapes include square rectangular and triangular
As well as a variety of colours sizes and shapes LEDs also vary in their viewing angle This tells you how much the beam of light spreads out Standard LEDs have a viewing angle of 60deg but others have a narrow beam of 30deg or less
Calculating an LED resistor value
An LED must have a resistor connected in series to limit the current through the LED otherwise it will burn out almost instantly
The resistor value R is given by
R = (VS - VL) I
VS = supply voltage VL = LED voltage (usually 2V but 4V for blue and white LEDs) I = LED current (eg 20mA) this must be less than the maximum permitted
If the calculated value is not available choose the nearest standard resistor value which is greater so that the current will be a little less than you chose In fact you may wish to choose a greater resistor value to reduce the current (to increase battery life for example) but this will make the LED less bright
Working out the LED resistor formula using Ohms law
Ohms law says that the resistance of the resistor R = VI where V = voltage across the resistor (= VS - VL in this case) I = the current through the resistor
So R = (VS - VL) I
BUZZERS
A buzzer or beeper (BUZZERS) is a signalling device usually electronic typically used in automobiles household appliances such as a microwave oven or game shows It most commonly consists of a number of switches or sensors connected to a control unit that determines if and which button was pushed or a preset time has lapsed and usually illuminates a light on the appropriate button or control panel and sounds a warning in the form of a continuous or intermittent buzzing
or beeping sound Initially this device was based on an electromechanical system which was identical to an electric bell without the metal gong (which makes the ringing noise) Often these units were anchored to a wall or ceiling and used the ceiling or wall as a sounding board Another implementation with some AC-connected devices was to implement a circuit to make the AC current into a noise loud enough to drive a loudspeaker and hook this circuit up to a cheap 8-ohm speaker Nowadays it is more popular to use a ceramic-based piezoelectric sounder which makes a high-pitched tone Usually these were hooked up to driver circuits which varied the pitch of the sound or pulsed the sound on and off
The word buzzer comes from the rasping noise that buzzers made when they were electromechanical devices operated from stepped-down AC line voltage at 50 or 60 cycles Other sounds commonly used to indicate that a button has been pressed are a ring or a beep
MOTORS
An electric motor is a device using electrical energy to produce mechanical energy nearly always by the interaction of magnetic fields and current-carrying conductors The reverse process that of using mechanical energy to produce electrical energy is accomplished by a generator or dynamo Traction motors used on vehicles often perform both tasks
Electric motors are found in myriad uses such as industrial fans blowers and pumps machine tools household appliances power tools and computer disk drives among
many other applications Electric motors may be operated by direct current from a battery in a portable device or motor vehicle or from alternating current from a central electrical distribution grid The smallest motors may be found in electric wristwatches Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses The very largest electric motors are used for propulsion of large ships and for such purposes as pipeline compressors with ratings in the thousands of kilowatts Electric motors may be classified by the source of electric power by their internal construction and by application
The physical principle of production of mechanical force by the interaction of an electric current and a magnetic field was known as early as 1821 Electric motors of increasing efficiency were constructed throughout the 19th century but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks
CONNECTORS
A DC connector is an electrical connector for
supplying direct current (DC) power DC connectors
are poorly standardized compared to domestic AC
power plugs and sockets DC plug is a common name
used for one common type of cylindrical two-conductor
plug available in a range of sizes and used to power
small pieces of electronic equipment It is also used to
describe some older multi-pin plugs
Several competing standards exist for DC plugs and in some cases incompatible plugs
will fit together to avoid damaging equipment these conditions must be true
Voltage must match
Polarity is correct
Current ratings are sufficient
Power supply filtering and stability is adequate
for the equipment being powered
Non-matching connectors are forced together
12V DC BATTERY
Features
Less than a 12 volt self discharge per 6 months 4 ea 12Vdc outputs 20 AmpHours Built-charger Digital Voltmeter
Description
This unit supplies a full 12Vdc at 20 AmpHours Designed for the officer that needs a power source that can be charged from 115Ac source or on the way to a incident from the car
The battery source has a very low self discharge rate which makes it perfect for law enforcement use The battery can set on the shelf for more than 6 months without recharging
Everyone knows when you grab a battery operated device the internal battery always requires several hours of charging before using The new voltage indicator reads out voltage to one hundredth of a volt for accurate operation The four outputs are 21mm plug Quick terminals and Cigarette lighter jack amp PT02 (Mil Spec) This model also allows powering
12Vdc sources while plugged in to 115Vac ldquoIts a UPSrdquo
SPECIFICATIONS OF COMPONENTS USED
PLC S7-200
INPUT POWER 230V AC 50 Hz
INPUTS 24 DC INPUTS
OUTPUTS 16 DC OUTPUTS
PROGRAM MEMORY 24
DATA MEMORY 10KB
EXPANSION MODULES 7
COMMUNICATION PORTS 2 RS 485
DIGITAL IO IMAGE SIZE 256(128 in 128 out)
EXECUTION SPEED 022microsecondsinstruction
SENSORS
SENSING RANGE 3mm
HOUSING MATERIAL Brass Nickel Plated
OPERATING VOLTAGE 10-30V
OPERATING CURRENT lt200mA
CONNECTION TYPE Cable
LEDS
DIAMETER 5mm
MAXIMUM VOLTAGE 1V
MAXIMUM CURRENT 10mA
INTENSITY
BUZZERS
OPERATING VOLTAGE30Vp-p
RATED FREQUENCY2000Hz 500Hz
OPERATING TEMP RANGE -20 to 60 degree
SOUND OUTPUT70 dB min10 cm
MOTOR
TOTAL LENGTH 46mm MOTOR DIAMETER 36mm MOTOR LENGTH 25mm DC SUPPLY 4 to 12V RPM 100 BRUSH TYPE Precious metal GEAR HEAD DIAMETER 37mm GEAR HEAD LENGTH 21mm OUTPUT SHAFT Centered SHAFT DIAMETER 4mm and 6mm
SHAFT LENGTH 22mm
- Block diagram of plc
- Applications
-
- Function
- Testing an LED
- Sizes Shapes and Viewing angles of LEDs
- Calculating an LED resistor value
-
- Working out the LED resistor formula using Ohms law
-
1048600 Using subroutines reduces the overall size of your program 1048600 Using subroutines decreases your scan time because you have moved the code out of the main program The S7-200 evaluates the code in the main program every scan cycle whether the code is executed or not but the S7-200 evaluates the code in the subroutine only when you call the subroutine and does not evaluate the code during the scans in which the subroutine is not called 1048600 Using subroutines creates code that is portable You can isolate the code for a function in a subroutine and then copy that subroutine into other programs with Interrupt RoutinesThese optional elements of your program react to specific interrupt events You design an interrupt routine to handle a pre-defined interrupt event Whenever the specified event occurs the S7-200 executes the interrupt routineThe interrupt routines are not called by your main program You associate an interrupt routine with an interrupt event and the S7-200 executes the instructions in the interrupt routine only on each occurrence of the interrupt event Other Elements of the ProgramOther blocks contain information for the S7-200 You can choose to download these blocks when you download your programSystem BlockThe system block allows you to configure different hardware options for the S7-200Data BlockThe data block stores the values for different variables (V memory) used by your program You can use the data block to enter initial values for the data
PROGRAMMING LANGUAGES IN PLC
IL (Instruction List) ndash mnemonic programming
LD (Ladder Diagram) ndash Relay logic
ST (Structured Text) ndash A C like programming language
FDB (Functional Block Diagram) ndash Graphical dataflow programming language
SFC (Sequential Flow Chart) ndash Graphical method for structured programs
Basic PLC Memory
Memory on a PLC is separated into 3 main areas
LOAD Memory
Can be RAM (dynamic) or EEPROM (retentive)
Used to store user programs
WORK Memory
Memory is RAM
When PLC starts Program is copied from LOAD memory to
WORK memory The program is then executed from Work
memory
SYSTEM Memory
Memory is RAM
Is used by micro-controller to implement counters timers interrupt
stacks etc
Contains a bit for each D I0
Contains ldquoMarker Memoryrdquo Marker memory is a free area of RAM
that can be used by the programmer
Contains ldquoProcess Input and Output Imagesrdquo Periodically the PLC
will store the states of the inputs to the Process Input Image and
Process Output Image to the output
SELECTION OF A PLC
Selection of PLC Based on
No of Inputs amp Outputs
Input Voltage
Memory
Scan Time
Special IO modules
Expansion Capabilities
Stand alone or Networked
Communication Capabilities
HOW PLC WORKS
Step 1-CHECKING INPUT STATUS
o PLC Scans each input
o Records the data in work memory
Step 2-EXECUTE PROGRAM
o PLC goes through the program logic step by step
o PLC executes the program depending on input status
o Write the output image in work memory
Step 3-UPDATE OUTPUT STATUS
o Changes the statues of the output onoff
o Again starts the cycle from step one
FEATURES OF S7-200
Allows Your Program to Immediately Read or Write the IO
Allows Your Program to Interrupt the Scan Cycle
Allows You to Allocate Processing Time for Communications
Tasks
Allows You to Set the States of Digital Outputs for Stop
CHECK
INPUT STATUS
EXECUTE
PROGRAM
UPDATE
OUTPUT STATUS
Mode
Allows You to Define Memory to Be Retained on Loss of Power
Allows You to Filter the Digital Inputs
Allows You to Filter the Analog Inputs
Allows You to Catch Pulses of Short Duration
Provides Password Protection
Provides Analog Adjustment Potentiometers
Provides High-speed IO
TECHNICAL FEATURES OF S7-200
Several models of CPUrsquos
o CPU 221 6in4out 2Kw program
o CPU 222 8in6out 2Kw program
o CPU 224 14in10out 4Kw program
o CPU 226 24in16out 4Kw program
Up to 256 digital input-outputs
Up to 32 analog channels
256 timers 256 counters
Built-in EEPROM memory
Real-time clockcalendar
Built-in communications
Password protection
Memory module
Removable input-output connectors
Wide range of expansion modules
o 8 pt input and output
o 4488 amp1616 inout combination
o 4 channel analog in 2 channel analog out
o 4 ch1ch analog inout combination
o 2 channel RTD in
o 4 channel thermocouple in
o PROFIBUS-DP Slave
o AS Interface master
SELECTING THE OPERATING MODE FOR THE S7- 200 CPU
The S7-200 has two modes of operation STOP mode and RUN mode The status LED on the front of the CPU indicates the current mode of operation In STOP mode the S7-200 is not executing the program and you can download a program or the CPU configuration In RUN mode the S7-200 is running the program
1048600 The S7-200 provides a mode switch for changing the mode of operation You can use the mode switch (located under the front access door of the S7-200) to manually select the operating mode setting the mode switch to STOP mode stops the execution of the program setting the mode switch to RUN mode starts the execution of the program and setting the mode switch to TERM (terminal) mode does not change the operating mode
If a power cycle occurs when the mode switch is set to either STOP or TERM the
S7-200 goes automatically to STOP mode when power is restored If a power cycle occurs when the mode switch is set to RUN the S7-200 goes to RUN mode when power is restored
1048600 STEP 7--MicroWIN allows you to change the operating mode of the online S7-200 To enable the software to change the operating mode you must manually set the mode switch on the S7-200 to either TERM or RUN You can use the PLC gt STOP or PLC gt RUN menu commands or the associated buttons on the toolbar to change the operating mode
1048600 You can insert the STOP instruction in your program to change the S7-200 to STOP mode This allows you to halt the execution of your program based on the program logic
ERRORS IN S7-200
Non-Fatal Errors
Non-fatal errors are those indicating problems with the construction of the user program with the execution of an instruction in the user program and with expansion IO modules You can use STEP 7--MicroWIN to view the error codes that were generated by the non-fatal error There are three basic categories of non-fatal errors
Program-compile errorsThe S7-200 compiles the program as it downloads If the S7-200 detects that the program violates a compilation rule the download is aborted and an error code is generated (A program that was already downloaded to the S7-200 would still exist in the EEPROM and would not be lost) After you correct your program you can download it again
IO errorsAt startup the S7-200 reads the IO configuration from each module During normal operation the S7-200 periodically checks the status of each module and compares it against the configuration obtained during startup If the S7-200 detects a difference the S7-200 sets the configuration error bit in the module error register The S7-200 does not read input data from or write output data to that module until the module configuration again matches the one obtained at startupThe module status information is stored in special memory (SM) bits Your program can monitor and evaluate these bits Refer to Appendix D for more information about the SM bits used for reporting IO errors SM50 is the global IO error bit and remains set while an error condition exists on an expansion module
Program execution errorsYour program can create error conditions while being executed These errors can result from improper use of an instruction or from the processing of invalid data by an instruction For example an indirect-address pointer that was valid when the program compiled could be modified during the execution of the program to point to an out-of-range address This is an example of a run-time programming problem SM43 is setupon the occurrence of a run-time programming problem and remains set while the S7-200 is in RUN mode Program execution error information is stored in special memory (SM) bits Your program can monitor and evaluate these bits The S7-200 does not change to STOP mode when it detects a non-fatal error It only logs the event in SM memory and continues with the execution of your program However you can design your program to force the S7-200 to STOP mode when a non-fatal error is detected
Fatal Errors
Fatal errors cause the S7-200 to stop the execution of your program Depending upon the severity of the fatal error it can render the S7-200 incapable of performing any or all functions The objective for handling fatal errors is to bring the S7-200 to a safe state from which the S7-200 can respond to interrogations about the existing error conditions When a fatal error is detected the S7-200 changes to STOP mode turns on the System Fault LED and the STOP LED overrides the output table and turns off the outputsThe S7-200 remains in this condition until the fatal error condition is corrected
Once you have made the changes to correct the fatal error condition use one of the following methods to restart the S7-200 1048600 Turn the power off and then on 1048600 Change the mode switch from RUN or TERM to STOP 1048600 Select the PLC gt Power-Up Reset menu command from STEP 7--MicroWIN
to restart the S7-200This forces the S7-200 to restart and clear any fatal errors
Restarting the S7-200 clears the fatal error condition and performs power-up diagnostic testing to verify that the fatal error has been corrected If another fatal error condition is found the S7-200 again sets the fault LED indicating that an error still exists Otherwise the S7-200 begins normal operation
Some error conditions can render the S7-200 incapable of communication In these cases you cannot view the error code from the S7-200 These types of errors indicate hardware failures that require the S7-200 to be repaired they cannot be fixed by changes to the program or clearing the memory of the S7-200
APPLICATIONS OF S7-200
Conveyer Systems
Elevators
Test Stations
Placement Systems
Woodworking Machinery
Packaging Equipment
Car Wash Automation
Remote Monitoring And Controlling For Water Wastewater
FEATURES OF LADDER DIAGRAMS
The LAD editor displays the program as a graphical representation similar to electrical wiring diagrams
Ladder programs allow the program to emulate the flow of electric current from a power source through a series of logical input conditions that in turn enable logical output conditions
A LAD program includes a left power rail that is energized Contacts that are closed allow energy to flow through them to the next element and contacts that are open block that energy flow
The logic is separated into networks The program is executed one network at a time from left to right and then top to bottom as dictated by the program Figure shows an example of a LAD program
The various instructions are represented by graphic symbols and include three basic forms
Contacts represent logic input conditions such as switches buttons or internal conditions
Coils usually represent logic output results such as lamps motor starters interposing relays or internal output conditions
Boxes represent additional instructions such as timers counters or math instructions Figure Sample LAD Program
Consider these main points when you select the LAD editor 1048600 Ladder logic is easy for beginning programmers to use 1048600 Graphical representation is easy to understand and is popular around the world 1048600 The LAD editor can be used with both the SIMATIC and IEC 1131--3 Instruction sets
1048600 You can always use the STL editor to display a program created with
the SIMATIC LAD editor
COMPONENTS LIST
Cardboard of 4050 sqcm
PLC S7-200
Sensors
LEDS
Buzzers
Motor
Contactors
Power supply
12v DC battery
Connecting wires
PPI Cable
SENSORS
A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact A proximity sensor often emits an electromagnetic or electrostatic field or a beam of electromagnetic radiation (infrared for instance) and looks for changes in the field or return signal The object being sensed is often referred to as the proximity sensors target Different
proximity sensor targets demand different sensors For example a capacitive or photoelectric sensor might be suitable for a plastic target an inductive proximity sensor requires a metal target
The maximum distance that this sensor can detect is defined nominal range Some sensors have adjustments of the nominal range or means to report a graduated detection distance
Proximity sensors can have a high reliability and long functional life because of the absence of mechanical parts and lack of physical contact between sensor and the sensed object
IEC 60947-5-2 defines the technical details of proximity sensors
A proximity sensor adjusted to a very short range is often used as a touch switch
Applications
Car bumpers that sense distance to nearby cars for parking
Ground proximity warning system for aviation safety Vibration Position measurements of rotating shafts in
machinery Sheet break sensing in paper machine Anti-aircraft artillery
LEDS
Example Circuit symbol
FunctionLEDs emit light when an electric current passes through them
Testing an LED
Never connect an LED directly to a battery or power supply
LEDs must have a resistor in series to limit the current to a safe value for quick testing purposes a 1k resistor is suitable for most LEDs if your supply voltage is 12V or less Remember to connect the LED the correct way round
Sizes Shapes and Viewing angles of LEDs
LEDs are available in a wide variety of sizes and shapes The standard LED has a round cross-section of 5mm diameter and this is probably the best type for general use but 3mm round LEDs are also popular
Round cross-section LEDs are frequently used and they are very easy to install on boxes by drilling a hole of the LED diameter adding a spot of glue will help to hold the LED if necessary LED clips are also available to secure LEDs in holes Other cross-section shapes include square rectangular and triangular
As well as a variety of colours sizes and shapes LEDs also vary in their viewing angle This tells you how much the beam of light spreads out Standard LEDs have a viewing angle of 60deg but others have a narrow beam of 30deg or less
Calculating an LED resistor value
An LED must have a resistor connected in series to limit the current through the LED otherwise it will burn out almost instantly
The resistor value R is given by
R = (VS - VL) I
VS = supply voltage VL = LED voltage (usually 2V but 4V for blue and white LEDs) I = LED current (eg 20mA) this must be less than the maximum permitted
If the calculated value is not available choose the nearest standard resistor value which is greater so that the current will be a little less than you chose In fact you may wish to choose a greater resistor value to reduce the current (to increase battery life for example) but this will make the LED less bright
Working out the LED resistor formula using Ohms law
Ohms law says that the resistance of the resistor R = VI where V = voltage across the resistor (= VS - VL in this case) I = the current through the resistor
So R = (VS - VL) I
BUZZERS
A buzzer or beeper (BUZZERS) is a signalling device usually electronic typically used in automobiles household appliances such as a microwave oven or game shows It most commonly consists of a number of switches or sensors connected to a control unit that determines if and which button was pushed or a preset time has lapsed and usually illuminates a light on the appropriate button or control panel and sounds a warning in the form of a continuous or intermittent buzzing
or beeping sound Initially this device was based on an electromechanical system which was identical to an electric bell without the metal gong (which makes the ringing noise) Often these units were anchored to a wall or ceiling and used the ceiling or wall as a sounding board Another implementation with some AC-connected devices was to implement a circuit to make the AC current into a noise loud enough to drive a loudspeaker and hook this circuit up to a cheap 8-ohm speaker Nowadays it is more popular to use a ceramic-based piezoelectric sounder which makes a high-pitched tone Usually these were hooked up to driver circuits which varied the pitch of the sound or pulsed the sound on and off
The word buzzer comes from the rasping noise that buzzers made when they were electromechanical devices operated from stepped-down AC line voltage at 50 or 60 cycles Other sounds commonly used to indicate that a button has been pressed are a ring or a beep
MOTORS
An electric motor is a device using electrical energy to produce mechanical energy nearly always by the interaction of magnetic fields and current-carrying conductors The reverse process that of using mechanical energy to produce electrical energy is accomplished by a generator or dynamo Traction motors used on vehicles often perform both tasks
Electric motors are found in myriad uses such as industrial fans blowers and pumps machine tools household appliances power tools and computer disk drives among
many other applications Electric motors may be operated by direct current from a battery in a portable device or motor vehicle or from alternating current from a central electrical distribution grid The smallest motors may be found in electric wristwatches Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses The very largest electric motors are used for propulsion of large ships and for such purposes as pipeline compressors with ratings in the thousands of kilowatts Electric motors may be classified by the source of electric power by their internal construction and by application
The physical principle of production of mechanical force by the interaction of an electric current and a magnetic field was known as early as 1821 Electric motors of increasing efficiency were constructed throughout the 19th century but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks
CONNECTORS
A DC connector is an electrical connector for
supplying direct current (DC) power DC connectors
are poorly standardized compared to domestic AC
power plugs and sockets DC plug is a common name
used for one common type of cylindrical two-conductor
plug available in a range of sizes and used to power
small pieces of electronic equipment It is also used to
describe some older multi-pin plugs
Several competing standards exist for DC plugs and in some cases incompatible plugs
will fit together to avoid damaging equipment these conditions must be true
Voltage must match
Polarity is correct
Current ratings are sufficient
Power supply filtering and stability is adequate
for the equipment being powered
Non-matching connectors are forced together
12V DC BATTERY
Features
Less than a 12 volt self discharge per 6 months 4 ea 12Vdc outputs 20 AmpHours Built-charger Digital Voltmeter
Description
This unit supplies a full 12Vdc at 20 AmpHours Designed for the officer that needs a power source that can be charged from 115Ac source or on the way to a incident from the car
The battery source has a very low self discharge rate which makes it perfect for law enforcement use The battery can set on the shelf for more than 6 months without recharging
Everyone knows when you grab a battery operated device the internal battery always requires several hours of charging before using The new voltage indicator reads out voltage to one hundredth of a volt for accurate operation The four outputs are 21mm plug Quick terminals and Cigarette lighter jack amp PT02 (Mil Spec) This model also allows powering
12Vdc sources while plugged in to 115Vac ldquoIts a UPSrdquo
SPECIFICATIONS OF COMPONENTS USED
PLC S7-200
INPUT POWER 230V AC 50 Hz
INPUTS 24 DC INPUTS
OUTPUTS 16 DC OUTPUTS
PROGRAM MEMORY 24
DATA MEMORY 10KB
EXPANSION MODULES 7
COMMUNICATION PORTS 2 RS 485
DIGITAL IO IMAGE SIZE 256(128 in 128 out)
EXECUTION SPEED 022microsecondsinstruction
SENSORS
SENSING RANGE 3mm
HOUSING MATERIAL Brass Nickel Plated
OPERATING VOLTAGE 10-30V
OPERATING CURRENT lt200mA
CONNECTION TYPE Cable
LEDS
DIAMETER 5mm
MAXIMUM VOLTAGE 1V
MAXIMUM CURRENT 10mA
INTENSITY
BUZZERS
OPERATING VOLTAGE30Vp-p
RATED FREQUENCY2000Hz 500Hz
OPERATING TEMP RANGE -20 to 60 degree
SOUND OUTPUT70 dB min10 cm
MOTOR
TOTAL LENGTH 46mm MOTOR DIAMETER 36mm MOTOR LENGTH 25mm DC SUPPLY 4 to 12V RPM 100 BRUSH TYPE Precious metal GEAR HEAD DIAMETER 37mm GEAR HEAD LENGTH 21mm OUTPUT SHAFT Centered SHAFT DIAMETER 4mm and 6mm
SHAFT LENGTH 22mm
- Block diagram of plc
- Applications
-
- Function
- Testing an LED
- Sizes Shapes and Viewing angles of LEDs
- Calculating an LED resistor value
-
- Working out the LED resistor formula using Ohms law
-
SFC (Sequential Flow Chart) ndash Graphical method for structured programs
Basic PLC Memory
Memory on a PLC is separated into 3 main areas
LOAD Memory
Can be RAM (dynamic) or EEPROM (retentive)
Used to store user programs
WORK Memory
Memory is RAM
When PLC starts Program is copied from LOAD memory to
WORK memory The program is then executed from Work
memory
SYSTEM Memory
Memory is RAM
Is used by micro-controller to implement counters timers interrupt
stacks etc
Contains a bit for each D I0
Contains ldquoMarker Memoryrdquo Marker memory is a free area of RAM
that can be used by the programmer
Contains ldquoProcess Input and Output Imagesrdquo Periodically the PLC
will store the states of the inputs to the Process Input Image and
Process Output Image to the output
SELECTION OF A PLC
Selection of PLC Based on
No of Inputs amp Outputs
Input Voltage
Memory
Scan Time
Special IO modules
Expansion Capabilities
Stand alone or Networked
Communication Capabilities
HOW PLC WORKS
Step 1-CHECKING INPUT STATUS
o PLC Scans each input
o Records the data in work memory
Step 2-EXECUTE PROGRAM
o PLC goes through the program logic step by step
o PLC executes the program depending on input status
o Write the output image in work memory
Step 3-UPDATE OUTPUT STATUS
o Changes the statues of the output onoff
o Again starts the cycle from step one
FEATURES OF S7-200
Allows Your Program to Immediately Read or Write the IO
Allows Your Program to Interrupt the Scan Cycle
Allows You to Allocate Processing Time for Communications
Tasks
Allows You to Set the States of Digital Outputs for Stop
CHECK
INPUT STATUS
EXECUTE
PROGRAM
UPDATE
OUTPUT STATUS
Mode
Allows You to Define Memory to Be Retained on Loss of Power
Allows You to Filter the Digital Inputs
Allows You to Filter the Analog Inputs
Allows You to Catch Pulses of Short Duration
Provides Password Protection
Provides Analog Adjustment Potentiometers
Provides High-speed IO
TECHNICAL FEATURES OF S7-200
Several models of CPUrsquos
o CPU 221 6in4out 2Kw program
o CPU 222 8in6out 2Kw program
o CPU 224 14in10out 4Kw program
o CPU 226 24in16out 4Kw program
Up to 256 digital input-outputs
Up to 32 analog channels
256 timers 256 counters
Built-in EEPROM memory
Real-time clockcalendar
Built-in communications
Password protection
Memory module
Removable input-output connectors
Wide range of expansion modules
o 8 pt input and output
o 4488 amp1616 inout combination
o 4 channel analog in 2 channel analog out
o 4 ch1ch analog inout combination
o 2 channel RTD in
o 4 channel thermocouple in
o PROFIBUS-DP Slave
o AS Interface master
SELECTING THE OPERATING MODE FOR THE S7- 200 CPU
The S7-200 has two modes of operation STOP mode and RUN mode The status LED on the front of the CPU indicates the current mode of operation In STOP mode the S7-200 is not executing the program and you can download a program or the CPU configuration In RUN mode the S7-200 is running the program
1048600 The S7-200 provides a mode switch for changing the mode of operation You can use the mode switch (located under the front access door of the S7-200) to manually select the operating mode setting the mode switch to STOP mode stops the execution of the program setting the mode switch to RUN mode starts the execution of the program and setting the mode switch to TERM (terminal) mode does not change the operating mode
If a power cycle occurs when the mode switch is set to either STOP or TERM the
S7-200 goes automatically to STOP mode when power is restored If a power cycle occurs when the mode switch is set to RUN the S7-200 goes to RUN mode when power is restored
1048600 STEP 7--MicroWIN allows you to change the operating mode of the online S7-200 To enable the software to change the operating mode you must manually set the mode switch on the S7-200 to either TERM or RUN You can use the PLC gt STOP or PLC gt RUN menu commands or the associated buttons on the toolbar to change the operating mode
1048600 You can insert the STOP instruction in your program to change the S7-200 to STOP mode This allows you to halt the execution of your program based on the program logic
ERRORS IN S7-200
Non-Fatal Errors
Non-fatal errors are those indicating problems with the construction of the user program with the execution of an instruction in the user program and with expansion IO modules You can use STEP 7--MicroWIN to view the error codes that were generated by the non-fatal error There are three basic categories of non-fatal errors
Program-compile errorsThe S7-200 compiles the program as it downloads If the S7-200 detects that the program violates a compilation rule the download is aborted and an error code is generated (A program that was already downloaded to the S7-200 would still exist in the EEPROM and would not be lost) After you correct your program you can download it again
IO errorsAt startup the S7-200 reads the IO configuration from each module During normal operation the S7-200 periodically checks the status of each module and compares it against the configuration obtained during startup If the S7-200 detects a difference the S7-200 sets the configuration error bit in the module error register The S7-200 does not read input data from or write output data to that module until the module configuration again matches the one obtained at startupThe module status information is stored in special memory (SM) bits Your program can monitor and evaluate these bits Refer to Appendix D for more information about the SM bits used for reporting IO errors SM50 is the global IO error bit and remains set while an error condition exists on an expansion module
Program execution errorsYour program can create error conditions while being executed These errors can result from improper use of an instruction or from the processing of invalid data by an instruction For example an indirect-address pointer that was valid when the program compiled could be modified during the execution of the program to point to an out-of-range address This is an example of a run-time programming problem SM43 is setupon the occurrence of a run-time programming problem and remains set while the S7-200 is in RUN mode Program execution error information is stored in special memory (SM) bits Your program can monitor and evaluate these bits The S7-200 does not change to STOP mode when it detects a non-fatal error It only logs the event in SM memory and continues with the execution of your program However you can design your program to force the S7-200 to STOP mode when a non-fatal error is detected
Fatal Errors
Fatal errors cause the S7-200 to stop the execution of your program Depending upon the severity of the fatal error it can render the S7-200 incapable of performing any or all functions The objective for handling fatal errors is to bring the S7-200 to a safe state from which the S7-200 can respond to interrogations about the existing error conditions When a fatal error is detected the S7-200 changes to STOP mode turns on the System Fault LED and the STOP LED overrides the output table and turns off the outputsThe S7-200 remains in this condition until the fatal error condition is corrected
Once you have made the changes to correct the fatal error condition use one of the following methods to restart the S7-200 1048600 Turn the power off and then on 1048600 Change the mode switch from RUN or TERM to STOP 1048600 Select the PLC gt Power-Up Reset menu command from STEP 7--MicroWIN
to restart the S7-200This forces the S7-200 to restart and clear any fatal errors
Restarting the S7-200 clears the fatal error condition and performs power-up diagnostic testing to verify that the fatal error has been corrected If another fatal error condition is found the S7-200 again sets the fault LED indicating that an error still exists Otherwise the S7-200 begins normal operation
Some error conditions can render the S7-200 incapable of communication In these cases you cannot view the error code from the S7-200 These types of errors indicate hardware failures that require the S7-200 to be repaired they cannot be fixed by changes to the program or clearing the memory of the S7-200
APPLICATIONS OF S7-200
Conveyer Systems
Elevators
Test Stations
Placement Systems
Woodworking Machinery
Packaging Equipment
Car Wash Automation
Remote Monitoring And Controlling For Water Wastewater
FEATURES OF LADDER DIAGRAMS
The LAD editor displays the program as a graphical representation similar to electrical wiring diagrams
Ladder programs allow the program to emulate the flow of electric current from a power source through a series of logical input conditions that in turn enable logical output conditions
A LAD program includes a left power rail that is energized Contacts that are closed allow energy to flow through them to the next element and contacts that are open block that energy flow
The logic is separated into networks The program is executed one network at a time from left to right and then top to bottom as dictated by the program Figure shows an example of a LAD program
The various instructions are represented by graphic symbols and include three basic forms
Contacts represent logic input conditions such as switches buttons or internal conditions
Coils usually represent logic output results such as lamps motor starters interposing relays or internal output conditions
Boxes represent additional instructions such as timers counters or math instructions Figure Sample LAD Program
Consider these main points when you select the LAD editor 1048600 Ladder logic is easy for beginning programmers to use 1048600 Graphical representation is easy to understand and is popular around the world 1048600 The LAD editor can be used with both the SIMATIC and IEC 1131--3 Instruction sets
1048600 You can always use the STL editor to display a program created with
the SIMATIC LAD editor
COMPONENTS LIST
Cardboard of 4050 sqcm
PLC S7-200
Sensors
LEDS
Buzzers
Motor
Contactors
Power supply
12v DC battery
Connecting wires
PPI Cable
SENSORS
A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact A proximity sensor often emits an electromagnetic or electrostatic field or a beam of electromagnetic radiation (infrared for instance) and looks for changes in the field or return signal The object being sensed is often referred to as the proximity sensors target Different
proximity sensor targets demand different sensors For example a capacitive or photoelectric sensor might be suitable for a plastic target an inductive proximity sensor requires a metal target
The maximum distance that this sensor can detect is defined nominal range Some sensors have adjustments of the nominal range or means to report a graduated detection distance
Proximity sensors can have a high reliability and long functional life because of the absence of mechanical parts and lack of physical contact between sensor and the sensed object
IEC 60947-5-2 defines the technical details of proximity sensors
A proximity sensor adjusted to a very short range is often used as a touch switch
Applications
Car bumpers that sense distance to nearby cars for parking
Ground proximity warning system for aviation safety Vibration Position measurements of rotating shafts in
machinery Sheet break sensing in paper machine Anti-aircraft artillery
LEDS
Example Circuit symbol
FunctionLEDs emit light when an electric current passes through them
Testing an LED
Never connect an LED directly to a battery or power supply
LEDs must have a resistor in series to limit the current to a safe value for quick testing purposes a 1k resistor is suitable for most LEDs if your supply voltage is 12V or less Remember to connect the LED the correct way round
Sizes Shapes and Viewing angles of LEDs
LEDs are available in a wide variety of sizes and shapes The standard LED has a round cross-section of 5mm diameter and this is probably the best type for general use but 3mm round LEDs are also popular
Round cross-section LEDs are frequently used and they are very easy to install on boxes by drilling a hole of the LED diameter adding a spot of glue will help to hold the LED if necessary LED clips are also available to secure LEDs in holes Other cross-section shapes include square rectangular and triangular
As well as a variety of colours sizes and shapes LEDs also vary in their viewing angle This tells you how much the beam of light spreads out Standard LEDs have a viewing angle of 60deg but others have a narrow beam of 30deg or less
Calculating an LED resistor value
An LED must have a resistor connected in series to limit the current through the LED otherwise it will burn out almost instantly
The resistor value R is given by
R = (VS - VL) I
VS = supply voltage VL = LED voltage (usually 2V but 4V for blue and white LEDs) I = LED current (eg 20mA) this must be less than the maximum permitted
If the calculated value is not available choose the nearest standard resistor value which is greater so that the current will be a little less than you chose In fact you may wish to choose a greater resistor value to reduce the current (to increase battery life for example) but this will make the LED less bright
Working out the LED resistor formula using Ohms law
Ohms law says that the resistance of the resistor R = VI where V = voltage across the resistor (= VS - VL in this case) I = the current through the resistor
So R = (VS - VL) I
BUZZERS
A buzzer or beeper (BUZZERS) is a signalling device usually electronic typically used in automobiles household appliances such as a microwave oven or game shows It most commonly consists of a number of switches or sensors connected to a control unit that determines if and which button was pushed or a preset time has lapsed and usually illuminates a light on the appropriate button or control panel and sounds a warning in the form of a continuous or intermittent buzzing
or beeping sound Initially this device was based on an electromechanical system which was identical to an electric bell without the metal gong (which makes the ringing noise) Often these units were anchored to a wall or ceiling and used the ceiling or wall as a sounding board Another implementation with some AC-connected devices was to implement a circuit to make the AC current into a noise loud enough to drive a loudspeaker and hook this circuit up to a cheap 8-ohm speaker Nowadays it is more popular to use a ceramic-based piezoelectric sounder which makes a high-pitched tone Usually these were hooked up to driver circuits which varied the pitch of the sound or pulsed the sound on and off
The word buzzer comes from the rasping noise that buzzers made when they were electromechanical devices operated from stepped-down AC line voltage at 50 or 60 cycles Other sounds commonly used to indicate that a button has been pressed are a ring or a beep
MOTORS
An electric motor is a device using electrical energy to produce mechanical energy nearly always by the interaction of magnetic fields and current-carrying conductors The reverse process that of using mechanical energy to produce electrical energy is accomplished by a generator or dynamo Traction motors used on vehicles often perform both tasks
Electric motors are found in myriad uses such as industrial fans blowers and pumps machine tools household appliances power tools and computer disk drives among
many other applications Electric motors may be operated by direct current from a battery in a portable device or motor vehicle or from alternating current from a central electrical distribution grid The smallest motors may be found in electric wristwatches Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses The very largest electric motors are used for propulsion of large ships and for such purposes as pipeline compressors with ratings in the thousands of kilowatts Electric motors may be classified by the source of electric power by their internal construction and by application
The physical principle of production of mechanical force by the interaction of an electric current and a magnetic field was known as early as 1821 Electric motors of increasing efficiency were constructed throughout the 19th century but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks
CONNECTORS
A DC connector is an electrical connector for
supplying direct current (DC) power DC connectors
are poorly standardized compared to domestic AC
power plugs and sockets DC plug is a common name
used for one common type of cylindrical two-conductor
plug available in a range of sizes and used to power
small pieces of electronic equipment It is also used to
describe some older multi-pin plugs
Several competing standards exist for DC plugs and in some cases incompatible plugs
will fit together to avoid damaging equipment these conditions must be true
Voltage must match
Polarity is correct
Current ratings are sufficient
Power supply filtering and stability is adequate
for the equipment being powered
Non-matching connectors are forced together
12V DC BATTERY
Features
Less than a 12 volt self discharge per 6 months 4 ea 12Vdc outputs 20 AmpHours Built-charger Digital Voltmeter
Description
This unit supplies a full 12Vdc at 20 AmpHours Designed for the officer that needs a power source that can be charged from 115Ac source or on the way to a incident from the car
The battery source has a very low self discharge rate which makes it perfect for law enforcement use The battery can set on the shelf for more than 6 months without recharging
Everyone knows when you grab a battery operated device the internal battery always requires several hours of charging before using The new voltage indicator reads out voltage to one hundredth of a volt for accurate operation The four outputs are 21mm plug Quick terminals and Cigarette lighter jack amp PT02 (Mil Spec) This model also allows powering
12Vdc sources while plugged in to 115Vac ldquoIts a UPSrdquo
SPECIFICATIONS OF COMPONENTS USED
PLC S7-200
INPUT POWER 230V AC 50 Hz
INPUTS 24 DC INPUTS
OUTPUTS 16 DC OUTPUTS
PROGRAM MEMORY 24
DATA MEMORY 10KB
EXPANSION MODULES 7
COMMUNICATION PORTS 2 RS 485
DIGITAL IO IMAGE SIZE 256(128 in 128 out)
EXECUTION SPEED 022microsecondsinstruction
SENSORS
SENSING RANGE 3mm
HOUSING MATERIAL Brass Nickel Plated
OPERATING VOLTAGE 10-30V
OPERATING CURRENT lt200mA
CONNECTION TYPE Cable
LEDS
DIAMETER 5mm
MAXIMUM VOLTAGE 1V
MAXIMUM CURRENT 10mA
INTENSITY
BUZZERS
OPERATING VOLTAGE30Vp-p
RATED FREQUENCY2000Hz 500Hz
OPERATING TEMP RANGE -20 to 60 degree
SOUND OUTPUT70 dB min10 cm
MOTOR
TOTAL LENGTH 46mm MOTOR DIAMETER 36mm MOTOR LENGTH 25mm DC SUPPLY 4 to 12V RPM 100 BRUSH TYPE Precious metal GEAR HEAD DIAMETER 37mm GEAR HEAD LENGTH 21mm OUTPUT SHAFT Centered SHAFT DIAMETER 4mm and 6mm
SHAFT LENGTH 22mm
- Block diagram of plc
- Applications
-
- Function
- Testing an LED
- Sizes Shapes and Viewing angles of LEDs
- Calculating an LED resistor value
-
- Working out the LED resistor formula using Ohms law
-
Can be RAM (dynamic) or EEPROM (retentive)
Used to store user programs
WORK Memory
Memory is RAM
When PLC starts Program is copied from LOAD memory to
WORK memory The program is then executed from Work
memory
SYSTEM Memory
Memory is RAM
Is used by micro-controller to implement counters timers interrupt
stacks etc
Contains a bit for each D I0
Contains ldquoMarker Memoryrdquo Marker memory is a free area of RAM
that can be used by the programmer
Contains ldquoProcess Input and Output Imagesrdquo Periodically the PLC
will store the states of the inputs to the Process Input Image and
Process Output Image to the output
SELECTION OF A PLC
Selection of PLC Based on
No of Inputs amp Outputs
Input Voltage
Memory
Scan Time
Special IO modules
Expansion Capabilities
Stand alone or Networked
Communication Capabilities
HOW PLC WORKS
Step 1-CHECKING INPUT STATUS
o PLC Scans each input
o Records the data in work memory
Step 2-EXECUTE PROGRAM
o PLC goes through the program logic step by step
o PLC executes the program depending on input status
o Write the output image in work memory
Step 3-UPDATE OUTPUT STATUS
o Changes the statues of the output onoff
o Again starts the cycle from step one
FEATURES OF S7-200
Allows Your Program to Immediately Read or Write the IO
Allows Your Program to Interrupt the Scan Cycle
Allows You to Allocate Processing Time for Communications
Tasks
Allows You to Set the States of Digital Outputs for Stop
CHECK
INPUT STATUS
EXECUTE
PROGRAM
UPDATE
OUTPUT STATUS
Mode
Allows You to Define Memory to Be Retained on Loss of Power
Allows You to Filter the Digital Inputs
Allows You to Filter the Analog Inputs
Allows You to Catch Pulses of Short Duration
Provides Password Protection
Provides Analog Adjustment Potentiometers
Provides High-speed IO
TECHNICAL FEATURES OF S7-200
Several models of CPUrsquos
o CPU 221 6in4out 2Kw program
o CPU 222 8in6out 2Kw program
o CPU 224 14in10out 4Kw program
o CPU 226 24in16out 4Kw program
Up to 256 digital input-outputs
Up to 32 analog channels
256 timers 256 counters
Built-in EEPROM memory
Real-time clockcalendar
Built-in communications
Password protection
Memory module
Removable input-output connectors
Wide range of expansion modules
o 8 pt input and output
o 4488 amp1616 inout combination
o 4 channel analog in 2 channel analog out
o 4 ch1ch analog inout combination
o 2 channel RTD in
o 4 channel thermocouple in
o PROFIBUS-DP Slave
o AS Interface master
SELECTING THE OPERATING MODE FOR THE S7- 200 CPU
The S7-200 has two modes of operation STOP mode and RUN mode The status LED on the front of the CPU indicates the current mode of operation In STOP mode the S7-200 is not executing the program and you can download a program or the CPU configuration In RUN mode the S7-200 is running the program
1048600 The S7-200 provides a mode switch for changing the mode of operation You can use the mode switch (located under the front access door of the S7-200) to manually select the operating mode setting the mode switch to STOP mode stops the execution of the program setting the mode switch to RUN mode starts the execution of the program and setting the mode switch to TERM (terminal) mode does not change the operating mode
If a power cycle occurs when the mode switch is set to either STOP or TERM the
S7-200 goes automatically to STOP mode when power is restored If a power cycle occurs when the mode switch is set to RUN the S7-200 goes to RUN mode when power is restored
1048600 STEP 7--MicroWIN allows you to change the operating mode of the online S7-200 To enable the software to change the operating mode you must manually set the mode switch on the S7-200 to either TERM or RUN You can use the PLC gt STOP or PLC gt RUN menu commands or the associated buttons on the toolbar to change the operating mode
1048600 You can insert the STOP instruction in your program to change the S7-200 to STOP mode This allows you to halt the execution of your program based on the program logic
ERRORS IN S7-200
Non-Fatal Errors
Non-fatal errors are those indicating problems with the construction of the user program with the execution of an instruction in the user program and with expansion IO modules You can use STEP 7--MicroWIN to view the error codes that were generated by the non-fatal error There are three basic categories of non-fatal errors
Program-compile errorsThe S7-200 compiles the program as it downloads If the S7-200 detects that the program violates a compilation rule the download is aborted and an error code is generated (A program that was already downloaded to the S7-200 would still exist in the EEPROM and would not be lost) After you correct your program you can download it again
IO errorsAt startup the S7-200 reads the IO configuration from each module During normal operation the S7-200 periodically checks the status of each module and compares it against the configuration obtained during startup If the S7-200 detects a difference the S7-200 sets the configuration error bit in the module error register The S7-200 does not read input data from or write output data to that module until the module configuration again matches the one obtained at startupThe module status information is stored in special memory (SM) bits Your program can monitor and evaluate these bits Refer to Appendix D for more information about the SM bits used for reporting IO errors SM50 is the global IO error bit and remains set while an error condition exists on an expansion module
Program execution errorsYour program can create error conditions while being executed These errors can result from improper use of an instruction or from the processing of invalid data by an instruction For example an indirect-address pointer that was valid when the program compiled could be modified during the execution of the program to point to an out-of-range address This is an example of a run-time programming problem SM43 is setupon the occurrence of a run-time programming problem and remains set while the S7-200 is in RUN mode Program execution error information is stored in special memory (SM) bits Your program can monitor and evaluate these bits The S7-200 does not change to STOP mode when it detects a non-fatal error It only logs the event in SM memory and continues with the execution of your program However you can design your program to force the S7-200 to STOP mode when a non-fatal error is detected
Fatal Errors
Fatal errors cause the S7-200 to stop the execution of your program Depending upon the severity of the fatal error it can render the S7-200 incapable of performing any or all functions The objective for handling fatal errors is to bring the S7-200 to a safe state from which the S7-200 can respond to interrogations about the existing error conditions When a fatal error is detected the S7-200 changes to STOP mode turns on the System Fault LED and the STOP LED overrides the output table and turns off the outputsThe S7-200 remains in this condition until the fatal error condition is corrected
Once you have made the changes to correct the fatal error condition use one of the following methods to restart the S7-200 1048600 Turn the power off and then on 1048600 Change the mode switch from RUN or TERM to STOP 1048600 Select the PLC gt Power-Up Reset menu command from STEP 7--MicroWIN
to restart the S7-200This forces the S7-200 to restart and clear any fatal errors
Restarting the S7-200 clears the fatal error condition and performs power-up diagnostic testing to verify that the fatal error has been corrected If another fatal error condition is found the S7-200 again sets the fault LED indicating that an error still exists Otherwise the S7-200 begins normal operation
Some error conditions can render the S7-200 incapable of communication In these cases you cannot view the error code from the S7-200 These types of errors indicate hardware failures that require the S7-200 to be repaired they cannot be fixed by changes to the program or clearing the memory of the S7-200
APPLICATIONS OF S7-200
Conveyer Systems
Elevators
Test Stations
Placement Systems
Woodworking Machinery
Packaging Equipment
Car Wash Automation
Remote Monitoring And Controlling For Water Wastewater
FEATURES OF LADDER DIAGRAMS
The LAD editor displays the program as a graphical representation similar to electrical wiring diagrams
Ladder programs allow the program to emulate the flow of electric current from a power source through a series of logical input conditions that in turn enable logical output conditions
A LAD program includes a left power rail that is energized Contacts that are closed allow energy to flow through them to the next element and contacts that are open block that energy flow
The logic is separated into networks The program is executed one network at a time from left to right and then top to bottom as dictated by the program Figure shows an example of a LAD program
The various instructions are represented by graphic symbols and include three basic forms
Contacts represent logic input conditions such as switches buttons or internal conditions
Coils usually represent logic output results such as lamps motor starters interposing relays or internal output conditions
Boxes represent additional instructions such as timers counters or math instructions Figure Sample LAD Program
Consider these main points when you select the LAD editor 1048600 Ladder logic is easy for beginning programmers to use 1048600 Graphical representation is easy to understand and is popular around the world 1048600 The LAD editor can be used with both the SIMATIC and IEC 1131--3 Instruction sets
1048600 You can always use the STL editor to display a program created with
the SIMATIC LAD editor
COMPONENTS LIST
Cardboard of 4050 sqcm
PLC S7-200
Sensors
LEDS
Buzzers
Motor
Contactors
Power supply
12v DC battery
Connecting wires
PPI Cable
SENSORS
A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact A proximity sensor often emits an electromagnetic or electrostatic field or a beam of electromagnetic radiation (infrared for instance) and looks for changes in the field or return signal The object being sensed is often referred to as the proximity sensors target Different
proximity sensor targets demand different sensors For example a capacitive or photoelectric sensor might be suitable for a plastic target an inductive proximity sensor requires a metal target
The maximum distance that this sensor can detect is defined nominal range Some sensors have adjustments of the nominal range or means to report a graduated detection distance
Proximity sensors can have a high reliability and long functional life because of the absence of mechanical parts and lack of physical contact between sensor and the sensed object
IEC 60947-5-2 defines the technical details of proximity sensors
A proximity sensor adjusted to a very short range is often used as a touch switch
Applications
Car bumpers that sense distance to nearby cars for parking
Ground proximity warning system for aviation safety Vibration Position measurements of rotating shafts in
machinery Sheet break sensing in paper machine Anti-aircraft artillery
LEDS
Example Circuit symbol
FunctionLEDs emit light when an electric current passes through them
Testing an LED
Never connect an LED directly to a battery or power supply
LEDs must have a resistor in series to limit the current to a safe value for quick testing purposes a 1k resistor is suitable for most LEDs if your supply voltage is 12V or less Remember to connect the LED the correct way round
Sizes Shapes and Viewing angles of LEDs
LEDs are available in a wide variety of sizes and shapes The standard LED has a round cross-section of 5mm diameter and this is probably the best type for general use but 3mm round LEDs are also popular
Round cross-section LEDs are frequently used and they are very easy to install on boxes by drilling a hole of the LED diameter adding a spot of glue will help to hold the LED if necessary LED clips are also available to secure LEDs in holes Other cross-section shapes include square rectangular and triangular
As well as a variety of colours sizes and shapes LEDs also vary in their viewing angle This tells you how much the beam of light spreads out Standard LEDs have a viewing angle of 60deg but others have a narrow beam of 30deg or less
Calculating an LED resistor value
An LED must have a resistor connected in series to limit the current through the LED otherwise it will burn out almost instantly
The resistor value R is given by
R = (VS - VL) I
VS = supply voltage VL = LED voltage (usually 2V but 4V for blue and white LEDs) I = LED current (eg 20mA) this must be less than the maximum permitted
If the calculated value is not available choose the nearest standard resistor value which is greater so that the current will be a little less than you chose In fact you may wish to choose a greater resistor value to reduce the current (to increase battery life for example) but this will make the LED less bright
Working out the LED resistor formula using Ohms law
Ohms law says that the resistance of the resistor R = VI where V = voltage across the resistor (= VS - VL in this case) I = the current through the resistor
So R = (VS - VL) I
BUZZERS
A buzzer or beeper (BUZZERS) is a signalling device usually electronic typically used in automobiles household appliances such as a microwave oven or game shows It most commonly consists of a number of switches or sensors connected to a control unit that determines if and which button was pushed or a preset time has lapsed and usually illuminates a light on the appropriate button or control panel and sounds a warning in the form of a continuous or intermittent buzzing
or beeping sound Initially this device was based on an electromechanical system which was identical to an electric bell without the metal gong (which makes the ringing noise) Often these units were anchored to a wall or ceiling and used the ceiling or wall as a sounding board Another implementation with some AC-connected devices was to implement a circuit to make the AC current into a noise loud enough to drive a loudspeaker and hook this circuit up to a cheap 8-ohm speaker Nowadays it is more popular to use a ceramic-based piezoelectric sounder which makes a high-pitched tone Usually these were hooked up to driver circuits which varied the pitch of the sound or pulsed the sound on and off
The word buzzer comes from the rasping noise that buzzers made when they were electromechanical devices operated from stepped-down AC line voltage at 50 or 60 cycles Other sounds commonly used to indicate that a button has been pressed are a ring or a beep
MOTORS
An electric motor is a device using electrical energy to produce mechanical energy nearly always by the interaction of magnetic fields and current-carrying conductors The reverse process that of using mechanical energy to produce electrical energy is accomplished by a generator or dynamo Traction motors used on vehicles often perform both tasks
Electric motors are found in myriad uses such as industrial fans blowers and pumps machine tools household appliances power tools and computer disk drives among
many other applications Electric motors may be operated by direct current from a battery in a portable device or motor vehicle or from alternating current from a central electrical distribution grid The smallest motors may be found in electric wristwatches Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses The very largest electric motors are used for propulsion of large ships and for such purposes as pipeline compressors with ratings in the thousands of kilowatts Electric motors may be classified by the source of electric power by their internal construction and by application
The physical principle of production of mechanical force by the interaction of an electric current and a magnetic field was known as early as 1821 Electric motors of increasing efficiency were constructed throughout the 19th century but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks
CONNECTORS
A DC connector is an electrical connector for
supplying direct current (DC) power DC connectors
are poorly standardized compared to domestic AC
power plugs and sockets DC plug is a common name
used for one common type of cylindrical two-conductor
plug available in a range of sizes and used to power
small pieces of electronic equipment It is also used to
describe some older multi-pin plugs
Several competing standards exist for DC plugs and in some cases incompatible plugs
will fit together to avoid damaging equipment these conditions must be true
Voltage must match
Polarity is correct
Current ratings are sufficient
Power supply filtering and stability is adequate
for the equipment being powered
Non-matching connectors are forced together
12V DC BATTERY
Features
Less than a 12 volt self discharge per 6 months 4 ea 12Vdc outputs 20 AmpHours Built-charger Digital Voltmeter
Description
This unit supplies a full 12Vdc at 20 AmpHours Designed for the officer that needs a power source that can be charged from 115Ac source or on the way to a incident from the car
The battery source has a very low self discharge rate which makes it perfect for law enforcement use The battery can set on the shelf for more than 6 months without recharging
Everyone knows when you grab a battery operated device the internal battery always requires several hours of charging before using The new voltage indicator reads out voltage to one hundredth of a volt for accurate operation The four outputs are 21mm plug Quick terminals and Cigarette lighter jack amp PT02 (Mil Spec) This model also allows powering
12Vdc sources while plugged in to 115Vac ldquoIts a UPSrdquo
SPECIFICATIONS OF COMPONENTS USED
PLC S7-200
INPUT POWER 230V AC 50 Hz
INPUTS 24 DC INPUTS
OUTPUTS 16 DC OUTPUTS
PROGRAM MEMORY 24
DATA MEMORY 10KB
EXPANSION MODULES 7
COMMUNICATION PORTS 2 RS 485
DIGITAL IO IMAGE SIZE 256(128 in 128 out)
EXECUTION SPEED 022microsecondsinstruction
SENSORS
SENSING RANGE 3mm
HOUSING MATERIAL Brass Nickel Plated
OPERATING VOLTAGE 10-30V
OPERATING CURRENT lt200mA
CONNECTION TYPE Cable
LEDS
DIAMETER 5mm
MAXIMUM VOLTAGE 1V
MAXIMUM CURRENT 10mA
INTENSITY
BUZZERS
OPERATING VOLTAGE30Vp-p
RATED FREQUENCY2000Hz 500Hz
OPERATING TEMP RANGE -20 to 60 degree
SOUND OUTPUT70 dB min10 cm
MOTOR
TOTAL LENGTH 46mm MOTOR DIAMETER 36mm MOTOR LENGTH 25mm DC SUPPLY 4 to 12V RPM 100 BRUSH TYPE Precious metal GEAR HEAD DIAMETER 37mm GEAR HEAD LENGTH 21mm OUTPUT SHAFT Centered SHAFT DIAMETER 4mm and 6mm
SHAFT LENGTH 22mm
- Block diagram of plc
- Applications
-
- Function
- Testing an LED
- Sizes Shapes and Viewing angles of LEDs
- Calculating an LED resistor value
-
- Working out the LED resistor formula using Ohms law
-
Input Voltage
Memory
Scan Time
Special IO modules
Expansion Capabilities
Stand alone or Networked
Communication Capabilities
HOW PLC WORKS
Step 1-CHECKING INPUT STATUS
o PLC Scans each input
o Records the data in work memory
Step 2-EXECUTE PROGRAM
o PLC goes through the program logic step by step
o PLC executes the program depending on input status
o Write the output image in work memory
Step 3-UPDATE OUTPUT STATUS
o Changes the statues of the output onoff
o Again starts the cycle from step one
FEATURES OF S7-200
Allows Your Program to Immediately Read or Write the IO
Allows Your Program to Interrupt the Scan Cycle
Allows You to Allocate Processing Time for Communications
Tasks
Allows You to Set the States of Digital Outputs for Stop
CHECK
INPUT STATUS
EXECUTE
PROGRAM
UPDATE
OUTPUT STATUS
Mode
Allows You to Define Memory to Be Retained on Loss of Power
Allows You to Filter the Digital Inputs
Allows You to Filter the Analog Inputs
Allows You to Catch Pulses of Short Duration
Provides Password Protection
Provides Analog Adjustment Potentiometers
Provides High-speed IO
TECHNICAL FEATURES OF S7-200
Several models of CPUrsquos
o CPU 221 6in4out 2Kw program
o CPU 222 8in6out 2Kw program
o CPU 224 14in10out 4Kw program
o CPU 226 24in16out 4Kw program
Up to 256 digital input-outputs
Up to 32 analog channels
256 timers 256 counters
Built-in EEPROM memory
Real-time clockcalendar
Built-in communications
Password protection
Memory module
Removable input-output connectors
Wide range of expansion modules
o 8 pt input and output
o 4488 amp1616 inout combination
o 4 channel analog in 2 channel analog out
o 4 ch1ch analog inout combination
o 2 channel RTD in
o 4 channel thermocouple in
o PROFIBUS-DP Slave
o AS Interface master
SELECTING THE OPERATING MODE FOR THE S7- 200 CPU
The S7-200 has two modes of operation STOP mode and RUN mode The status LED on the front of the CPU indicates the current mode of operation In STOP mode the S7-200 is not executing the program and you can download a program or the CPU configuration In RUN mode the S7-200 is running the program
1048600 The S7-200 provides a mode switch for changing the mode of operation You can use the mode switch (located under the front access door of the S7-200) to manually select the operating mode setting the mode switch to STOP mode stops the execution of the program setting the mode switch to RUN mode starts the execution of the program and setting the mode switch to TERM (terminal) mode does not change the operating mode
If a power cycle occurs when the mode switch is set to either STOP or TERM the
S7-200 goes automatically to STOP mode when power is restored If a power cycle occurs when the mode switch is set to RUN the S7-200 goes to RUN mode when power is restored
1048600 STEP 7--MicroWIN allows you to change the operating mode of the online S7-200 To enable the software to change the operating mode you must manually set the mode switch on the S7-200 to either TERM or RUN You can use the PLC gt STOP or PLC gt RUN menu commands or the associated buttons on the toolbar to change the operating mode
1048600 You can insert the STOP instruction in your program to change the S7-200 to STOP mode This allows you to halt the execution of your program based on the program logic
ERRORS IN S7-200
Non-Fatal Errors
Non-fatal errors are those indicating problems with the construction of the user program with the execution of an instruction in the user program and with expansion IO modules You can use STEP 7--MicroWIN to view the error codes that were generated by the non-fatal error There are three basic categories of non-fatal errors
Program-compile errorsThe S7-200 compiles the program as it downloads If the S7-200 detects that the program violates a compilation rule the download is aborted and an error code is generated (A program that was already downloaded to the S7-200 would still exist in the EEPROM and would not be lost) After you correct your program you can download it again
IO errorsAt startup the S7-200 reads the IO configuration from each module During normal operation the S7-200 periodically checks the status of each module and compares it against the configuration obtained during startup If the S7-200 detects a difference the S7-200 sets the configuration error bit in the module error register The S7-200 does not read input data from or write output data to that module until the module configuration again matches the one obtained at startupThe module status information is stored in special memory (SM) bits Your program can monitor and evaluate these bits Refer to Appendix D for more information about the SM bits used for reporting IO errors SM50 is the global IO error bit and remains set while an error condition exists on an expansion module
Program execution errorsYour program can create error conditions while being executed These errors can result from improper use of an instruction or from the processing of invalid data by an instruction For example an indirect-address pointer that was valid when the program compiled could be modified during the execution of the program to point to an out-of-range address This is an example of a run-time programming problem SM43 is setupon the occurrence of a run-time programming problem and remains set while the S7-200 is in RUN mode Program execution error information is stored in special memory (SM) bits Your program can monitor and evaluate these bits The S7-200 does not change to STOP mode when it detects a non-fatal error It only logs the event in SM memory and continues with the execution of your program However you can design your program to force the S7-200 to STOP mode when a non-fatal error is detected
Fatal Errors
Fatal errors cause the S7-200 to stop the execution of your program Depending upon the severity of the fatal error it can render the S7-200 incapable of performing any or all functions The objective for handling fatal errors is to bring the S7-200 to a safe state from which the S7-200 can respond to interrogations about the existing error conditions When a fatal error is detected the S7-200 changes to STOP mode turns on the System Fault LED and the STOP LED overrides the output table and turns off the outputsThe S7-200 remains in this condition until the fatal error condition is corrected
Once you have made the changes to correct the fatal error condition use one of the following methods to restart the S7-200 1048600 Turn the power off and then on 1048600 Change the mode switch from RUN or TERM to STOP 1048600 Select the PLC gt Power-Up Reset menu command from STEP 7--MicroWIN
to restart the S7-200This forces the S7-200 to restart and clear any fatal errors
Restarting the S7-200 clears the fatal error condition and performs power-up diagnostic testing to verify that the fatal error has been corrected If another fatal error condition is found the S7-200 again sets the fault LED indicating that an error still exists Otherwise the S7-200 begins normal operation
Some error conditions can render the S7-200 incapable of communication In these cases you cannot view the error code from the S7-200 These types of errors indicate hardware failures that require the S7-200 to be repaired they cannot be fixed by changes to the program or clearing the memory of the S7-200
APPLICATIONS OF S7-200
Conveyer Systems
Elevators
Test Stations
Placement Systems
Woodworking Machinery
Packaging Equipment
Car Wash Automation
Remote Monitoring And Controlling For Water Wastewater
FEATURES OF LADDER DIAGRAMS
The LAD editor displays the program as a graphical representation similar to electrical wiring diagrams
Ladder programs allow the program to emulate the flow of electric current from a power source through a series of logical input conditions that in turn enable logical output conditions
A LAD program includes a left power rail that is energized Contacts that are closed allow energy to flow through them to the next element and contacts that are open block that energy flow
The logic is separated into networks The program is executed one network at a time from left to right and then top to bottom as dictated by the program Figure shows an example of a LAD program
The various instructions are represented by graphic symbols and include three basic forms
Contacts represent logic input conditions such as switches buttons or internal conditions
Coils usually represent logic output results such as lamps motor starters interposing relays or internal output conditions
Boxes represent additional instructions such as timers counters or math instructions Figure Sample LAD Program
Consider these main points when you select the LAD editor 1048600 Ladder logic is easy for beginning programmers to use 1048600 Graphical representation is easy to understand and is popular around the world 1048600 The LAD editor can be used with both the SIMATIC and IEC 1131--3 Instruction sets
1048600 You can always use the STL editor to display a program created with
the SIMATIC LAD editor
COMPONENTS LIST
Cardboard of 4050 sqcm
PLC S7-200
Sensors
LEDS
Buzzers
Motor
Contactors
Power supply
12v DC battery
Connecting wires
PPI Cable
SENSORS
A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact A proximity sensor often emits an electromagnetic or electrostatic field or a beam of electromagnetic radiation (infrared for instance) and looks for changes in the field or return signal The object being sensed is often referred to as the proximity sensors target Different
proximity sensor targets demand different sensors For example a capacitive or photoelectric sensor might be suitable for a plastic target an inductive proximity sensor requires a metal target
The maximum distance that this sensor can detect is defined nominal range Some sensors have adjustments of the nominal range or means to report a graduated detection distance
Proximity sensors can have a high reliability and long functional life because of the absence of mechanical parts and lack of physical contact between sensor and the sensed object
IEC 60947-5-2 defines the technical details of proximity sensors
A proximity sensor adjusted to a very short range is often used as a touch switch
Applications
Car bumpers that sense distance to nearby cars for parking
Ground proximity warning system for aviation safety Vibration Position measurements of rotating shafts in
machinery Sheet break sensing in paper machine Anti-aircraft artillery
LEDS
Example Circuit symbol
FunctionLEDs emit light when an electric current passes through them
Testing an LED
Never connect an LED directly to a battery or power supply
LEDs must have a resistor in series to limit the current to a safe value for quick testing purposes a 1k resistor is suitable for most LEDs if your supply voltage is 12V or less Remember to connect the LED the correct way round
Sizes Shapes and Viewing angles of LEDs
LEDs are available in a wide variety of sizes and shapes The standard LED has a round cross-section of 5mm diameter and this is probably the best type for general use but 3mm round LEDs are also popular
Round cross-section LEDs are frequently used and they are very easy to install on boxes by drilling a hole of the LED diameter adding a spot of glue will help to hold the LED if necessary LED clips are also available to secure LEDs in holes Other cross-section shapes include square rectangular and triangular
As well as a variety of colours sizes and shapes LEDs also vary in their viewing angle This tells you how much the beam of light spreads out Standard LEDs have a viewing angle of 60deg but others have a narrow beam of 30deg or less
Calculating an LED resistor value
An LED must have a resistor connected in series to limit the current through the LED otherwise it will burn out almost instantly
The resistor value R is given by
R = (VS - VL) I
VS = supply voltage VL = LED voltage (usually 2V but 4V for blue and white LEDs) I = LED current (eg 20mA) this must be less than the maximum permitted
If the calculated value is not available choose the nearest standard resistor value which is greater so that the current will be a little less than you chose In fact you may wish to choose a greater resistor value to reduce the current (to increase battery life for example) but this will make the LED less bright
Working out the LED resistor formula using Ohms law
Ohms law says that the resistance of the resistor R = VI where V = voltage across the resistor (= VS - VL in this case) I = the current through the resistor
So R = (VS - VL) I
BUZZERS
A buzzer or beeper (BUZZERS) is a signalling device usually electronic typically used in automobiles household appliances such as a microwave oven or game shows It most commonly consists of a number of switches or sensors connected to a control unit that determines if and which button was pushed or a preset time has lapsed and usually illuminates a light on the appropriate button or control panel and sounds a warning in the form of a continuous or intermittent buzzing
or beeping sound Initially this device was based on an electromechanical system which was identical to an electric bell without the metal gong (which makes the ringing noise) Often these units were anchored to a wall or ceiling and used the ceiling or wall as a sounding board Another implementation with some AC-connected devices was to implement a circuit to make the AC current into a noise loud enough to drive a loudspeaker and hook this circuit up to a cheap 8-ohm speaker Nowadays it is more popular to use a ceramic-based piezoelectric sounder which makes a high-pitched tone Usually these were hooked up to driver circuits which varied the pitch of the sound or pulsed the sound on and off
The word buzzer comes from the rasping noise that buzzers made when they were electromechanical devices operated from stepped-down AC line voltage at 50 or 60 cycles Other sounds commonly used to indicate that a button has been pressed are a ring or a beep
MOTORS
An electric motor is a device using electrical energy to produce mechanical energy nearly always by the interaction of magnetic fields and current-carrying conductors The reverse process that of using mechanical energy to produce electrical energy is accomplished by a generator or dynamo Traction motors used on vehicles often perform both tasks
Electric motors are found in myriad uses such as industrial fans blowers and pumps machine tools household appliances power tools and computer disk drives among
many other applications Electric motors may be operated by direct current from a battery in a portable device or motor vehicle or from alternating current from a central electrical distribution grid The smallest motors may be found in electric wristwatches Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses The very largest electric motors are used for propulsion of large ships and for such purposes as pipeline compressors with ratings in the thousands of kilowatts Electric motors may be classified by the source of electric power by their internal construction and by application
The physical principle of production of mechanical force by the interaction of an electric current and a magnetic field was known as early as 1821 Electric motors of increasing efficiency were constructed throughout the 19th century but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks
CONNECTORS
A DC connector is an electrical connector for
supplying direct current (DC) power DC connectors
are poorly standardized compared to domestic AC
power plugs and sockets DC plug is a common name
used for one common type of cylindrical two-conductor
plug available in a range of sizes and used to power
small pieces of electronic equipment It is also used to
describe some older multi-pin plugs
Several competing standards exist for DC plugs and in some cases incompatible plugs
will fit together to avoid damaging equipment these conditions must be true
Voltage must match
Polarity is correct
Current ratings are sufficient
Power supply filtering and stability is adequate
for the equipment being powered
Non-matching connectors are forced together
12V DC BATTERY
Features
Less than a 12 volt self discharge per 6 months 4 ea 12Vdc outputs 20 AmpHours Built-charger Digital Voltmeter
Description
This unit supplies a full 12Vdc at 20 AmpHours Designed for the officer that needs a power source that can be charged from 115Ac source or on the way to a incident from the car
The battery source has a very low self discharge rate which makes it perfect for law enforcement use The battery can set on the shelf for more than 6 months without recharging
Everyone knows when you grab a battery operated device the internal battery always requires several hours of charging before using The new voltage indicator reads out voltage to one hundredth of a volt for accurate operation The four outputs are 21mm plug Quick terminals and Cigarette lighter jack amp PT02 (Mil Spec) This model also allows powering
12Vdc sources while plugged in to 115Vac ldquoIts a UPSrdquo
SPECIFICATIONS OF COMPONENTS USED
PLC S7-200
INPUT POWER 230V AC 50 Hz
INPUTS 24 DC INPUTS
OUTPUTS 16 DC OUTPUTS
PROGRAM MEMORY 24
DATA MEMORY 10KB
EXPANSION MODULES 7
COMMUNICATION PORTS 2 RS 485
DIGITAL IO IMAGE SIZE 256(128 in 128 out)
EXECUTION SPEED 022microsecondsinstruction
SENSORS
SENSING RANGE 3mm
HOUSING MATERIAL Brass Nickel Plated
OPERATING VOLTAGE 10-30V
OPERATING CURRENT lt200mA
CONNECTION TYPE Cable
LEDS
DIAMETER 5mm
MAXIMUM VOLTAGE 1V
MAXIMUM CURRENT 10mA
INTENSITY
BUZZERS
OPERATING VOLTAGE30Vp-p
RATED FREQUENCY2000Hz 500Hz
OPERATING TEMP RANGE -20 to 60 degree
SOUND OUTPUT70 dB min10 cm
MOTOR
TOTAL LENGTH 46mm MOTOR DIAMETER 36mm MOTOR LENGTH 25mm DC SUPPLY 4 to 12V RPM 100 BRUSH TYPE Precious metal GEAR HEAD DIAMETER 37mm GEAR HEAD LENGTH 21mm OUTPUT SHAFT Centered SHAFT DIAMETER 4mm and 6mm
SHAFT LENGTH 22mm
- Block diagram of plc
- Applications
-
- Function
- Testing an LED
- Sizes Shapes and Viewing angles of LEDs
- Calculating an LED resistor value
-
- Working out the LED resistor formula using Ohms law
-
o Changes the statues of the output onoff
o Again starts the cycle from step one
FEATURES OF S7-200
Allows Your Program to Immediately Read or Write the IO
Allows Your Program to Interrupt the Scan Cycle
Allows You to Allocate Processing Time for Communications
Tasks
Allows You to Set the States of Digital Outputs for Stop
CHECK
INPUT STATUS
EXECUTE
PROGRAM
UPDATE
OUTPUT STATUS
Mode
Allows You to Define Memory to Be Retained on Loss of Power
Allows You to Filter the Digital Inputs
Allows You to Filter the Analog Inputs
Allows You to Catch Pulses of Short Duration
Provides Password Protection
Provides Analog Adjustment Potentiometers
Provides High-speed IO
TECHNICAL FEATURES OF S7-200
Several models of CPUrsquos
o CPU 221 6in4out 2Kw program
o CPU 222 8in6out 2Kw program
o CPU 224 14in10out 4Kw program
o CPU 226 24in16out 4Kw program
Up to 256 digital input-outputs
Up to 32 analog channels
256 timers 256 counters
Built-in EEPROM memory
Real-time clockcalendar
Built-in communications
Password protection
Memory module
Removable input-output connectors
Wide range of expansion modules
o 8 pt input and output
o 4488 amp1616 inout combination
o 4 channel analog in 2 channel analog out
o 4 ch1ch analog inout combination
o 2 channel RTD in
o 4 channel thermocouple in
o PROFIBUS-DP Slave
o AS Interface master
SELECTING THE OPERATING MODE FOR THE S7- 200 CPU
The S7-200 has two modes of operation STOP mode and RUN mode The status LED on the front of the CPU indicates the current mode of operation In STOP mode the S7-200 is not executing the program and you can download a program or the CPU configuration In RUN mode the S7-200 is running the program
1048600 The S7-200 provides a mode switch for changing the mode of operation You can use the mode switch (located under the front access door of the S7-200) to manually select the operating mode setting the mode switch to STOP mode stops the execution of the program setting the mode switch to RUN mode starts the execution of the program and setting the mode switch to TERM (terminal) mode does not change the operating mode
If a power cycle occurs when the mode switch is set to either STOP or TERM the
S7-200 goes automatically to STOP mode when power is restored If a power cycle occurs when the mode switch is set to RUN the S7-200 goes to RUN mode when power is restored
1048600 STEP 7--MicroWIN allows you to change the operating mode of the online S7-200 To enable the software to change the operating mode you must manually set the mode switch on the S7-200 to either TERM or RUN You can use the PLC gt STOP or PLC gt RUN menu commands or the associated buttons on the toolbar to change the operating mode
1048600 You can insert the STOP instruction in your program to change the S7-200 to STOP mode This allows you to halt the execution of your program based on the program logic
ERRORS IN S7-200
Non-Fatal Errors
Non-fatal errors are those indicating problems with the construction of the user program with the execution of an instruction in the user program and with expansion IO modules You can use STEP 7--MicroWIN to view the error codes that were generated by the non-fatal error There are three basic categories of non-fatal errors
Program-compile errorsThe S7-200 compiles the program as it downloads If the S7-200 detects that the program violates a compilation rule the download is aborted and an error code is generated (A program that was already downloaded to the S7-200 would still exist in the EEPROM and would not be lost) After you correct your program you can download it again
IO errorsAt startup the S7-200 reads the IO configuration from each module During normal operation the S7-200 periodically checks the status of each module and compares it against the configuration obtained during startup If the S7-200 detects a difference the S7-200 sets the configuration error bit in the module error register The S7-200 does not read input data from or write output data to that module until the module configuration again matches the one obtained at startupThe module status information is stored in special memory (SM) bits Your program can monitor and evaluate these bits Refer to Appendix D for more information about the SM bits used for reporting IO errors SM50 is the global IO error bit and remains set while an error condition exists on an expansion module
Program execution errorsYour program can create error conditions while being executed These errors can result from improper use of an instruction or from the processing of invalid data by an instruction For example an indirect-address pointer that was valid when the program compiled could be modified during the execution of the program to point to an out-of-range address This is an example of a run-time programming problem SM43 is setupon the occurrence of a run-time programming problem and remains set while the S7-200 is in RUN mode Program execution error information is stored in special memory (SM) bits Your program can monitor and evaluate these bits The S7-200 does not change to STOP mode when it detects a non-fatal error It only logs the event in SM memory and continues with the execution of your program However you can design your program to force the S7-200 to STOP mode when a non-fatal error is detected
Fatal Errors
Fatal errors cause the S7-200 to stop the execution of your program Depending upon the severity of the fatal error it can render the S7-200 incapable of performing any or all functions The objective for handling fatal errors is to bring the S7-200 to a safe state from which the S7-200 can respond to interrogations about the existing error conditions When a fatal error is detected the S7-200 changes to STOP mode turns on the System Fault LED and the STOP LED overrides the output table and turns off the outputsThe S7-200 remains in this condition until the fatal error condition is corrected
Once you have made the changes to correct the fatal error condition use one of the following methods to restart the S7-200 1048600 Turn the power off and then on 1048600 Change the mode switch from RUN or TERM to STOP 1048600 Select the PLC gt Power-Up Reset menu command from STEP 7--MicroWIN
to restart the S7-200This forces the S7-200 to restart and clear any fatal errors
Restarting the S7-200 clears the fatal error condition and performs power-up diagnostic testing to verify that the fatal error has been corrected If another fatal error condition is found the S7-200 again sets the fault LED indicating that an error still exists Otherwise the S7-200 begins normal operation
Some error conditions can render the S7-200 incapable of communication In these cases you cannot view the error code from the S7-200 These types of errors indicate hardware failures that require the S7-200 to be repaired they cannot be fixed by changes to the program or clearing the memory of the S7-200
APPLICATIONS OF S7-200
Conveyer Systems
Elevators
Test Stations
Placement Systems
Woodworking Machinery
Packaging Equipment
Car Wash Automation
Remote Monitoring And Controlling For Water Wastewater
FEATURES OF LADDER DIAGRAMS
The LAD editor displays the program as a graphical representation similar to electrical wiring diagrams
Ladder programs allow the program to emulate the flow of electric current from a power source through a series of logical input conditions that in turn enable logical output conditions
A LAD program includes a left power rail that is energized Contacts that are closed allow energy to flow through them to the next element and contacts that are open block that energy flow
The logic is separated into networks The program is executed one network at a time from left to right and then top to bottom as dictated by the program Figure shows an example of a LAD program
The various instructions are represented by graphic symbols and include three basic forms
Contacts represent logic input conditions such as switches buttons or internal conditions
Coils usually represent logic output results such as lamps motor starters interposing relays or internal output conditions
Boxes represent additional instructions such as timers counters or math instructions Figure Sample LAD Program
Consider these main points when you select the LAD editor 1048600 Ladder logic is easy for beginning programmers to use 1048600 Graphical representation is easy to understand and is popular around the world 1048600 The LAD editor can be used with both the SIMATIC and IEC 1131--3 Instruction sets
1048600 You can always use the STL editor to display a program created with
the SIMATIC LAD editor
COMPONENTS LIST
Cardboard of 4050 sqcm
PLC S7-200
Sensors
LEDS
Buzzers
Motor
Contactors
Power supply
12v DC battery
Connecting wires
PPI Cable
SENSORS
A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact A proximity sensor often emits an electromagnetic or electrostatic field or a beam of electromagnetic radiation (infrared for instance) and looks for changes in the field or return signal The object being sensed is often referred to as the proximity sensors target Different
proximity sensor targets demand different sensors For example a capacitive or photoelectric sensor might be suitable for a plastic target an inductive proximity sensor requires a metal target
The maximum distance that this sensor can detect is defined nominal range Some sensors have adjustments of the nominal range or means to report a graduated detection distance
Proximity sensors can have a high reliability and long functional life because of the absence of mechanical parts and lack of physical contact between sensor and the sensed object
IEC 60947-5-2 defines the technical details of proximity sensors
A proximity sensor adjusted to a very short range is often used as a touch switch
Applications
Car bumpers that sense distance to nearby cars for parking
Ground proximity warning system for aviation safety Vibration Position measurements of rotating shafts in
machinery Sheet break sensing in paper machine Anti-aircraft artillery
LEDS
Example Circuit symbol
FunctionLEDs emit light when an electric current passes through them
Testing an LED
Never connect an LED directly to a battery or power supply
LEDs must have a resistor in series to limit the current to a safe value for quick testing purposes a 1k resistor is suitable for most LEDs if your supply voltage is 12V or less Remember to connect the LED the correct way round
Sizes Shapes and Viewing angles of LEDs
LEDs are available in a wide variety of sizes and shapes The standard LED has a round cross-section of 5mm diameter and this is probably the best type for general use but 3mm round LEDs are also popular
Round cross-section LEDs are frequently used and they are very easy to install on boxes by drilling a hole of the LED diameter adding a spot of glue will help to hold the LED if necessary LED clips are also available to secure LEDs in holes Other cross-section shapes include square rectangular and triangular
As well as a variety of colours sizes and shapes LEDs also vary in their viewing angle This tells you how much the beam of light spreads out Standard LEDs have a viewing angle of 60deg but others have a narrow beam of 30deg or less
Calculating an LED resistor value
An LED must have a resistor connected in series to limit the current through the LED otherwise it will burn out almost instantly
The resistor value R is given by
R = (VS - VL) I
VS = supply voltage VL = LED voltage (usually 2V but 4V for blue and white LEDs) I = LED current (eg 20mA) this must be less than the maximum permitted
If the calculated value is not available choose the nearest standard resistor value which is greater so that the current will be a little less than you chose In fact you may wish to choose a greater resistor value to reduce the current (to increase battery life for example) but this will make the LED less bright
Working out the LED resistor formula using Ohms law
Ohms law says that the resistance of the resistor R = VI where V = voltage across the resistor (= VS - VL in this case) I = the current through the resistor
So R = (VS - VL) I
BUZZERS
A buzzer or beeper (BUZZERS) is a signalling device usually electronic typically used in automobiles household appliances such as a microwave oven or game shows It most commonly consists of a number of switches or sensors connected to a control unit that determines if and which button was pushed or a preset time has lapsed and usually illuminates a light on the appropriate button or control panel and sounds a warning in the form of a continuous or intermittent buzzing
or beeping sound Initially this device was based on an electromechanical system which was identical to an electric bell without the metal gong (which makes the ringing noise) Often these units were anchored to a wall or ceiling and used the ceiling or wall as a sounding board Another implementation with some AC-connected devices was to implement a circuit to make the AC current into a noise loud enough to drive a loudspeaker and hook this circuit up to a cheap 8-ohm speaker Nowadays it is more popular to use a ceramic-based piezoelectric sounder which makes a high-pitched tone Usually these were hooked up to driver circuits which varied the pitch of the sound or pulsed the sound on and off
The word buzzer comes from the rasping noise that buzzers made when they were electromechanical devices operated from stepped-down AC line voltage at 50 or 60 cycles Other sounds commonly used to indicate that a button has been pressed are a ring or a beep
MOTORS
An electric motor is a device using electrical energy to produce mechanical energy nearly always by the interaction of magnetic fields and current-carrying conductors The reverse process that of using mechanical energy to produce electrical energy is accomplished by a generator or dynamo Traction motors used on vehicles often perform both tasks
Electric motors are found in myriad uses such as industrial fans blowers and pumps machine tools household appliances power tools and computer disk drives among
many other applications Electric motors may be operated by direct current from a battery in a portable device or motor vehicle or from alternating current from a central electrical distribution grid The smallest motors may be found in electric wristwatches Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses The very largest electric motors are used for propulsion of large ships and for such purposes as pipeline compressors with ratings in the thousands of kilowatts Electric motors may be classified by the source of electric power by their internal construction and by application
The physical principle of production of mechanical force by the interaction of an electric current and a magnetic field was known as early as 1821 Electric motors of increasing efficiency were constructed throughout the 19th century but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks
CONNECTORS
A DC connector is an electrical connector for
supplying direct current (DC) power DC connectors
are poorly standardized compared to domestic AC
power plugs and sockets DC plug is a common name
used for one common type of cylindrical two-conductor
plug available in a range of sizes and used to power
small pieces of electronic equipment It is also used to
describe some older multi-pin plugs
Several competing standards exist for DC plugs and in some cases incompatible plugs
will fit together to avoid damaging equipment these conditions must be true
Voltage must match
Polarity is correct
Current ratings are sufficient
Power supply filtering and stability is adequate
for the equipment being powered
Non-matching connectors are forced together
12V DC BATTERY
Features
Less than a 12 volt self discharge per 6 months 4 ea 12Vdc outputs 20 AmpHours Built-charger Digital Voltmeter
Description
This unit supplies a full 12Vdc at 20 AmpHours Designed for the officer that needs a power source that can be charged from 115Ac source or on the way to a incident from the car
The battery source has a very low self discharge rate which makes it perfect for law enforcement use The battery can set on the shelf for more than 6 months without recharging
Everyone knows when you grab a battery operated device the internal battery always requires several hours of charging before using The new voltage indicator reads out voltage to one hundredth of a volt for accurate operation The four outputs are 21mm plug Quick terminals and Cigarette lighter jack amp PT02 (Mil Spec) This model also allows powering
12Vdc sources while plugged in to 115Vac ldquoIts a UPSrdquo
SPECIFICATIONS OF COMPONENTS USED
PLC S7-200
INPUT POWER 230V AC 50 Hz
INPUTS 24 DC INPUTS
OUTPUTS 16 DC OUTPUTS
PROGRAM MEMORY 24
DATA MEMORY 10KB
EXPANSION MODULES 7
COMMUNICATION PORTS 2 RS 485
DIGITAL IO IMAGE SIZE 256(128 in 128 out)
EXECUTION SPEED 022microsecondsinstruction
SENSORS
SENSING RANGE 3mm
HOUSING MATERIAL Brass Nickel Plated
OPERATING VOLTAGE 10-30V
OPERATING CURRENT lt200mA
CONNECTION TYPE Cable
LEDS
DIAMETER 5mm
MAXIMUM VOLTAGE 1V
MAXIMUM CURRENT 10mA
INTENSITY
BUZZERS
OPERATING VOLTAGE30Vp-p
RATED FREQUENCY2000Hz 500Hz
OPERATING TEMP RANGE -20 to 60 degree
SOUND OUTPUT70 dB min10 cm
MOTOR
TOTAL LENGTH 46mm MOTOR DIAMETER 36mm MOTOR LENGTH 25mm DC SUPPLY 4 to 12V RPM 100 BRUSH TYPE Precious metal GEAR HEAD DIAMETER 37mm GEAR HEAD LENGTH 21mm OUTPUT SHAFT Centered SHAFT DIAMETER 4mm and 6mm
SHAFT LENGTH 22mm
- Block diagram of plc
- Applications
-
- Function
- Testing an LED
- Sizes Shapes and Viewing angles of LEDs
- Calculating an LED resistor value
-
- Working out the LED resistor formula using Ohms law
-
Mode
Allows You to Define Memory to Be Retained on Loss of Power
Allows You to Filter the Digital Inputs
Allows You to Filter the Analog Inputs
Allows You to Catch Pulses of Short Duration
Provides Password Protection
Provides Analog Adjustment Potentiometers
Provides High-speed IO
TECHNICAL FEATURES OF S7-200
Several models of CPUrsquos
o CPU 221 6in4out 2Kw program
o CPU 222 8in6out 2Kw program
o CPU 224 14in10out 4Kw program
o CPU 226 24in16out 4Kw program
Up to 256 digital input-outputs
Up to 32 analog channels
256 timers 256 counters
Built-in EEPROM memory
Real-time clockcalendar
Built-in communications
Password protection
Memory module
Removable input-output connectors
Wide range of expansion modules
o 8 pt input and output
o 4488 amp1616 inout combination
o 4 channel analog in 2 channel analog out
o 4 ch1ch analog inout combination
o 2 channel RTD in
o 4 channel thermocouple in
o PROFIBUS-DP Slave
o AS Interface master
SELECTING THE OPERATING MODE FOR THE S7- 200 CPU
The S7-200 has two modes of operation STOP mode and RUN mode The status LED on the front of the CPU indicates the current mode of operation In STOP mode the S7-200 is not executing the program and you can download a program or the CPU configuration In RUN mode the S7-200 is running the program
1048600 The S7-200 provides a mode switch for changing the mode of operation You can use the mode switch (located under the front access door of the S7-200) to manually select the operating mode setting the mode switch to STOP mode stops the execution of the program setting the mode switch to RUN mode starts the execution of the program and setting the mode switch to TERM (terminal) mode does not change the operating mode
If a power cycle occurs when the mode switch is set to either STOP or TERM the
S7-200 goes automatically to STOP mode when power is restored If a power cycle occurs when the mode switch is set to RUN the S7-200 goes to RUN mode when power is restored
1048600 STEP 7--MicroWIN allows you to change the operating mode of the online S7-200 To enable the software to change the operating mode you must manually set the mode switch on the S7-200 to either TERM or RUN You can use the PLC gt STOP or PLC gt RUN menu commands or the associated buttons on the toolbar to change the operating mode
1048600 You can insert the STOP instruction in your program to change the S7-200 to STOP mode This allows you to halt the execution of your program based on the program logic
ERRORS IN S7-200
Non-Fatal Errors
Non-fatal errors are those indicating problems with the construction of the user program with the execution of an instruction in the user program and with expansion IO modules You can use STEP 7--MicroWIN to view the error codes that were generated by the non-fatal error There are three basic categories of non-fatal errors
Program-compile errorsThe S7-200 compiles the program as it downloads If the S7-200 detects that the program violates a compilation rule the download is aborted and an error code is generated (A program that was already downloaded to the S7-200 would still exist in the EEPROM and would not be lost) After you correct your program you can download it again
IO errorsAt startup the S7-200 reads the IO configuration from each module During normal operation the S7-200 periodically checks the status of each module and compares it against the configuration obtained during startup If the S7-200 detects a difference the S7-200 sets the configuration error bit in the module error register The S7-200 does not read input data from or write output data to that module until the module configuration again matches the one obtained at startupThe module status information is stored in special memory (SM) bits Your program can monitor and evaluate these bits Refer to Appendix D for more information about the SM bits used for reporting IO errors SM50 is the global IO error bit and remains set while an error condition exists on an expansion module
Program execution errorsYour program can create error conditions while being executed These errors can result from improper use of an instruction or from the processing of invalid data by an instruction For example an indirect-address pointer that was valid when the program compiled could be modified during the execution of the program to point to an out-of-range address This is an example of a run-time programming problem SM43 is setupon the occurrence of a run-time programming problem and remains set while the S7-200 is in RUN mode Program execution error information is stored in special memory (SM) bits Your program can monitor and evaluate these bits The S7-200 does not change to STOP mode when it detects a non-fatal error It only logs the event in SM memory and continues with the execution of your program However you can design your program to force the S7-200 to STOP mode when a non-fatal error is detected
Fatal Errors
Fatal errors cause the S7-200 to stop the execution of your program Depending upon the severity of the fatal error it can render the S7-200 incapable of performing any or all functions The objective for handling fatal errors is to bring the S7-200 to a safe state from which the S7-200 can respond to interrogations about the existing error conditions When a fatal error is detected the S7-200 changes to STOP mode turns on the System Fault LED and the STOP LED overrides the output table and turns off the outputsThe S7-200 remains in this condition until the fatal error condition is corrected
Once you have made the changes to correct the fatal error condition use one of the following methods to restart the S7-200 1048600 Turn the power off and then on 1048600 Change the mode switch from RUN or TERM to STOP 1048600 Select the PLC gt Power-Up Reset menu command from STEP 7--MicroWIN
to restart the S7-200This forces the S7-200 to restart and clear any fatal errors
Restarting the S7-200 clears the fatal error condition and performs power-up diagnostic testing to verify that the fatal error has been corrected If another fatal error condition is found the S7-200 again sets the fault LED indicating that an error still exists Otherwise the S7-200 begins normal operation
Some error conditions can render the S7-200 incapable of communication In these cases you cannot view the error code from the S7-200 These types of errors indicate hardware failures that require the S7-200 to be repaired they cannot be fixed by changes to the program or clearing the memory of the S7-200
APPLICATIONS OF S7-200
Conveyer Systems
Elevators
Test Stations
Placement Systems
Woodworking Machinery
Packaging Equipment
Car Wash Automation
Remote Monitoring And Controlling For Water Wastewater
FEATURES OF LADDER DIAGRAMS
The LAD editor displays the program as a graphical representation similar to electrical wiring diagrams
Ladder programs allow the program to emulate the flow of electric current from a power source through a series of logical input conditions that in turn enable logical output conditions
A LAD program includes a left power rail that is energized Contacts that are closed allow energy to flow through them to the next element and contacts that are open block that energy flow
The logic is separated into networks The program is executed one network at a time from left to right and then top to bottom as dictated by the program Figure shows an example of a LAD program
The various instructions are represented by graphic symbols and include three basic forms
Contacts represent logic input conditions such as switches buttons or internal conditions
Coils usually represent logic output results such as lamps motor starters interposing relays or internal output conditions
Boxes represent additional instructions such as timers counters or math instructions Figure Sample LAD Program
Consider these main points when you select the LAD editor 1048600 Ladder logic is easy for beginning programmers to use 1048600 Graphical representation is easy to understand and is popular around the world 1048600 The LAD editor can be used with both the SIMATIC and IEC 1131--3 Instruction sets
1048600 You can always use the STL editor to display a program created with
the SIMATIC LAD editor
COMPONENTS LIST
Cardboard of 4050 sqcm
PLC S7-200
Sensors
LEDS
Buzzers
Motor
Contactors
Power supply
12v DC battery
Connecting wires
PPI Cable
SENSORS
A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact A proximity sensor often emits an electromagnetic or electrostatic field or a beam of electromagnetic radiation (infrared for instance) and looks for changes in the field or return signal The object being sensed is often referred to as the proximity sensors target Different
proximity sensor targets demand different sensors For example a capacitive or photoelectric sensor might be suitable for a plastic target an inductive proximity sensor requires a metal target
The maximum distance that this sensor can detect is defined nominal range Some sensors have adjustments of the nominal range or means to report a graduated detection distance
Proximity sensors can have a high reliability and long functional life because of the absence of mechanical parts and lack of physical contact between sensor and the sensed object
IEC 60947-5-2 defines the technical details of proximity sensors
A proximity sensor adjusted to a very short range is often used as a touch switch
Applications
Car bumpers that sense distance to nearby cars for parking
Ground proximity warning system for aviation safety Vibration Position measurements of rotating shafts in
machinery Sheet break sensing in paper machine Anti-aircraft artillery
LEDS
Example Circuit symbol
FunctionLEDs emit light when an electric current passes through them
Testing an LED
Never connect an LED directly to a battery or power supply
LEDs must have a resistor in series to limit the current to a safe value for quick testing purposes a 1k resistor is suitable for most LEDs if your supply voltage is 12V or less Remember to connect the LED the correct way round
Sizes Shapes and Viewing angles of LEDs
LEDs are available in a wide variety of sizes and shapes The standard LED has a round cross-section of 5mm diameter and this is probably the best type for general use but 3mm round LEDs are also popular
Round cross-section LEDs are frequently used and they are very easy to install on boxes by drilling a hole of the LED diameter adding a spot of glue will help to hold the LED if necessary LED clips are also available to secure LEDs in holes Other cross-section shapes include square rectangular and triangular
As well as a variety of colours sizes and shapes LEDs also vary in their viewing angle This tells you how much the beam of light spreads out Standard LEDs have a viewing angle of 60deg but others have a narrow beam of 30deg or less
Calculating an LED resistor value
An LED must have a resistor connected in series to limit the current through the LED otherwise it will burn out almost instantly
The resistor value R is given by
R = (VS - VL) I
VS = supply voltage VL = LED voltage (usually 2V but 4V for blue and white LEDs) I = LED current (eg 20mA) this must be less than the maximum permitted
If the calculated value is not available choose the nearest standard resistor value which is greater so that the current will be a little less than you chose In fact you may wish to choose a greater resistor value to reduce the current (to increase battery life for example) but this will make the LED less bright
Working out the LED resistor formula using Ohms law
Ohms law says that the resistance of the resistor R = VI where V = voltage across the resistor (= VS - VL in this case) I = the current through the resistor
So R = (VS - VL) I
BUZZERS
A buzzer or beeper (BUZZERS) is a signalling device usually electronic typically used in automobiles household appliances such as a microwave oven or game shows It most commonly consists of a number of switches or sensors connected to a control unit that determines if and which button was pushed or a preset time has lapsed and usually illuminates a light on the appropriate button or control panel and sounds a warning in the form of a continuous or intermittent buzzing
or beeping sound Initially this device was based on an electromechanical system which was identical to an electric bell without the metal gong (which makes the ringing noise) Often these units were anchored to a wall or ceiling and used the ceiling or wall as a sounding board Another implementation with some AC-connected devices was to implement a circuit to make the AC current into a noise loud enough to drive a loudspeaker and hook this circuit up to a cheap 8-ohm speaker Nowadays it is more popular to use a ceramic-based piezoelectric sounder which makes a high-pitched tone Usually these were hooked up to driver circuits which varied the pitch of the sound or pulsed the sound on and off
The word buzzer comes from the rasping noise that buzzers made when they were electromechanical devices operated from stepped-down AC line voltage at 50 or 60 cycles Other sounds commonly used to indicate that a button has been pressed are a ring or a beep
MOTORS
An electric motor is a device using electrical energy to produce mechanical energy nearly always by the interaction of magnetic fields and current-carrying conductors The reverse process that of using mechanical energy to produce electrical energy is accomplished by a generator or dynamo Traction motors used on vehicles often perform both tasks
Electric motors are found in myriad uses such as industrial fans blowers and pumps machine tools household appliances power tools and computer disk drives among
many other applications Electric motors may be operated by direct current from a battery in a portable device or motor vehicle or from alternating current from a central electrical distribution grid The smallest motors may be found in electric wristwatches Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses The very largest electric motors are used for propulsion of large ships and for such purposes as pipeline compressors with ratings in the thousands of kilowatts Electric motors may be classified by the source of electric power by their internal construction and by application
The physical principle of production of mechanical force by the interaction of an electric current and a magnetic field was known as early as 1821 Electric motors of increasing efficiency were constructed throughout the 19th century but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks
CONNECTORS
A DC connector is an electrical connector for
supplying direct current (DC) power DC connectors
are poorly standardized compared to domestic AC
power plugs and sockets DC plug is a common name
used for one common type of cylindrical two-conductor
plug available in a range of sizes and used to power
small pieces of electronic equipment It is also used to
describe some older multi-pin plugs
Several competing standards exist for DC plugs and in some cases incompatible plugs
will fit together to avoid damaging equipment these conditions must be true
Voltage must match
Polarity is correct
Current ratings are sufficient
Power supply filtering and stability is adequate
for the equipment being powered
Non-matching connectors are forced together
12V DC BATTERY
Features
Less than a 12 volt self discharge per 6 months 4 ea 12Vdc outputs 20 AmpHours Built-charger Digital Voltmeter
Description
This unit supplies a full 12Vdc at 20 AmpHours Designed for the officer that needs a power source that can be charged from 115Ac source or on the way to a incident from the car
The battery source has a very low self discharge rate which makes it perfect for law enforcement use The battery can set on the shelf for more than 6 months without recharging
Everyone knows when you grab a battery operated device the internal battery always requires several hours of charging before using The new voltage indicator reads out voltage to one hundredth of a volt for accurate operation The four outputs are 21mm plug Quick terminals and Cigarette lighter jack amp PT02 (Mil Spec) This model also allows powering
12Vdc sources while plugged in to 115Vac ldquoIts a UPSrdquo
SPECIFICATIONS OF COMPONENTS USED
PLC S7-200
INPUT POWER 230V AC 50 Hz
INPUTS 24 DC INPUTS
OUTPUTS 16 DC OUTPUTS
PROGRAM MEMORY 24
DATA MEMORY 10KB
EXPANSION MODULES 7
COMMUNICATION PORTS 2 RS 485
DIGITAL IO IMAGE SIZE 256(128 in 128 out)
EXECUTION SPEED 022microsecondsinstruction
SENSORS
SENSING RANGE 3mm
HOUSING MATERIAL Brass Nickel Plated
OPERATING VOLTAGE 10-30V
OPERATING CURRENT lt200mA
CONNECTION TYPE Cable
LEDS
DIAMETER 5mm
MAXIMUM VOLTAGE 1V
MAXIMUM CURRENT 10mA
INTENSITY
BUZZERS
OPERATING VOLTAGE30Vp-p
RATED FREQUENCY2000Hz 500Hz
OPERATING TEMP RANGE -20 to 60 degree
SOUND OUTPUT70 dB min10 cm
MOTOR
TOTAL LENGTH 46mm MOTOR DIAMETER 36mm MOTOR LENGTH 25mm DC SUPPLY 4 to 12V RPM 100 BRUSH TYPE Precious metal GEAR HEAD DIAMETER 37mm GEAR HEAD LENGTH 21mm OUTPUT SHAFT Centered SHAFT DIAMETER 4mm and 6mm
SHAFT LENGTH 22mm
- Block diagram of plc
- Applications
-
- Function
- Testing an LED
- Sizes Shapes and Viewing angles of LEDs
- Calculating an LED resistor value
-
- Working out the LED resistor formula using Ohms law
-
256 timers 256 counters
Built-in EEPROM memory
Real-time clockcalendar
Built-in communications
Password protection
Memory module
Removable input-output connectors
Wide range of expansion modules
o 8 pt input and output
o 4488 amp1616 inout combination
o 4 channel analog in 2 channel analog out
o 4 ch1ch analog inout combination
o 2 channel RTD in
o 4 channel thermocouple in
o PROFIBUS-DP Slave
o AS Interface master
SELECTING THE OPERATING MODE FOR THE S7- 200 CPU
The S7-200 has two modes of operation STOP mode and RUN mode The status LED on the front of the CPU indicates the current mode of operation In STOP mode the S7-200 is not executing the program and you can download a program or the CPU configuration In RUN mode the S7-200 is running the program
1048600 The S7-200 provides a mode switch for changing the mode of operation You can use the mode switch (located under the front access door of the S7-200) to manually select the operating mode setting the mode switch to STOP mode stops the execution of the program setting the mode switch to RUN mode starts the execution of the program and setting the mode switch to TERM (terminal) mode does not change the operating mode
If a power cycle occurs when the mode switch is set to either STOP or TERM the
S7-200 goes automatically to STOP mode when power is restored If a power cycle occurs when the mode switch is set to RUN the S7-200 goes to RUN mode when power is restored
1048600 STEP 7--MicroWIN allows you to change the operating mode of the online S7-200 To enable the software to change the operating mode you must manually set the mode switch on the S7-200 to either TERM or RUN You can use the PLC gt STOP or PLC gt RUN menu commands or the associated buttons on the toolbar to change the operating mode
1048600 You can insert the STOP instruction in your program to change the S7-200 to STOP mode This allows you to halt the execution of your program based on the program logic
ERRORS IN S7-200
Non-Fatal Errors
Non-fatal errors are those indicating problems with the construction of the user program with the execution of an instruction in the user program and with expansion IO modules You can use STEP 7--MicroWIN to view the error codes that were generated by the non-fatal error There are three basic categories of non-fatal errors
Program-compile errorsThe S7-200 compiles the program as it downloads If the S7-200 detects that the program violates a compilation rule the download is aborted and an error code is generated (A program that was already downloaded to the S7-200 would still exist in the EEPROM and would not be lost) After you correct your program you can download it again
IO errorsAt startup the S7-200 reads the IO configuration from each module During normal operation the S7-200 periodically checks the status of each module and compares it against the configuration obtained during startup If the S7-200 detects a difference the S7-200 sets the configuration error bit in the module error register The S7-200 does not read input data from or write output data to that module until the module configuration again matches the one obtained at startupThe module status information is stored in special memory (SM) bits Your program can monitor and evaluate these bits Refer to Appendix D for more information about the SM bits used for reporting IO errors SM50 is the global IO error bit and remains set while an error condition exists on an expansion module
Program execution errorsYour program can create error conditions while being executed These errors can result from improper use of an instruction or from the processing of invalid data by an instruction For example an indirect-address pointer that was valid when the program compiled could be modified during the execution of the program to point to an out-of-range address This is an example of a run-time programming problem SM43 is setupon the occurrence of a run-time programming problem and remains set while the S7-200 is in RUN mode Program execution error information is stored in special memory (SM) bits Your program can monitor and evaluate these bits The S7-200 does not change to STOP mode when it detects a non-fatal error It only logs the event in SM memory and continues with the execution of your program However you can design your program to force the S7-200 to STOP mode when a non-fatal error is detected
Fatal Errors
Fatal errors cause the S7-200 to stop the execution of your program Depending upon the severity of the fatal error it can render the S7-200 incapable of performing any or all functions The objective for handling fatal errors is to bring the S7-200 to a safe state from which the S7-200 can respond to interrogations about the existing error conditions When a fatal error is detected the S7-200 changes to STOP mode turns on the System Fault LED and the STOP LED overrides the output table and turns off the outputsThe S7-200 remains in this condition until the fatal error condition is corrected
Once you have made the changes to correct the fatal error condition use one of the following methods to restart the S7-200 1048600 Turn the power off and then on 1048600 Change the mode switch from RUN or TERM to STOP 1048600 Select the PLC gt Power-Up Reset menu command from STEP 7--MicroWIN
to restart the S7-200This forces the S7-200 to restart and clear any fatal errors
Restarting the S7-200 clears the fatal error condition and performs power-up diagnostic testing to verify that the fatal error has been corrected If another fatal error condition is found the S7-200 again sets the fault LED indicating that an error still exists Otherwise the S7-200 begins normal operation
Some error conditions can render the S7-200 incapable of communication In these cases you cannot view the error code from the S7-200 These types of errors indicate hardware failures that require the S7-200 to be repaired they cannot be fixed by changes to the program or clearing the memory of the S7-200
APPLICATIONS OF S7-200
Conveyer Systems
Elevators
Test Stations
Placement Systems
Woodworking Machinery
Packaging Equipment
Car Wash Automation
Remote Monitoring And Controlling For Water Wastewater
FEATURES OF LADDER DIAGRAMS
The LAD editor displays the program as a graphical representation similar to electrical wiring diagrams
Ladder programs allow the program to emulate the flow of electric current from a power source through a series of logical input conditions that in turn enable logical output conditions
A LAD program includes a left power rail that is energized Contacts that are closed allow energy to flow through them to the next element and contacts that are open block that energy flow
The logic is separated into networks The program is executed one network at a time from left to right and then top to bottom as dictated by the program Figure shows an example of a LAD program
The various instructions are represented by graphic symbols and include three basic forms
Contacts represent logic input conditions such as switches buttons or internal conditions
Coils usually represent logic output results such as lamps motor starters interposing relays or internal output conditions
Boxes represent additional instructions such as timers counters or math instructions Figure Sample LAD Program
Consider these main points when you select the LAD editor 1048600 Ladder logic is easy for beginning programmers to use 1048600 Graphical representation is easy to understand and is popular around the world 1048600 The LAD editor can be used with both the SIMATIC and IEC 1131--3 Instruction sets
1048600 You can always use the STL editor to display a program created with
the SIMATIC LAD editor
COMPONENTS LIST
Cardboard of 4050 sqcm
PLC S7-200
Sensors
LEDS
Buzzers
Motor
Contactors
Power supply
12v DC battery
Connecting wires
PPI Cable
SENSORS
A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact A proximity sensor often emits an electromagnetic or electrostatic field or a beam of electromagnetic radiation (infrared for instance) and looks for changes in the field or return signal The object being sensed is often referred to as the proximity sensors target Different
proximity sensor targets demand different sensors For example a capacitive or photoelectric sensor might be suitable for a plastic target an inductive proximity sensor requires a metal target
The maximum distance that this sensor can detect is defined nominal range Some sensors have adjustments of the nominal range or means to report a graduated detection distance
Proximity sensors can have a high reliability and long functional life because of the absence of mechanical parts and lack of physical contact between sensor and the sensed object
IEC 60947-5-2 defines the technical details of proximity sensors
A proximity sensor adjusted to a very short range is often used as a touch switch
Applications
Car bumpers that sense distance to nearby cars for parking
Ground proximity warning system for aviation safety Vibration Position measurements of rotating shafts in
machinery Sheet break sensing in paper machine Anti-aircraft artillery
LEDS
Example Circuit symbol
FunctionLEDs emit light when an electric current passes through them
Testing an LED
Never connect an LED directly to a battery or power supply
LEDs must have a resistor in series to limit the current to a safe value for quick testing purposes a 1k resistor is suitable for most LEDs if your supply voltage is 12V or less Remember to connect the LED the correct way round
Sizes Shapes and Viewing angles of LEDs
LEDs are available in a wide variety of sizes and shapes The standard LED has a round cross-section of 5mm diameter and this is probably the best type for general use but 3mm round LEDs are also popular
Round cross-section LEDs are frequently used and they are very easy to install on boxes by drilling a hole of the LED diameter adding a spot of glue will help to hold the LED if necessary LED clips are also available to secure LEDs in holes Other cross-section shapes include square rectangular and triangular
As well as a variety of colours sizes and shapes LEDs also vary in their viewing angle This tells you how much the beam of light spreads out Standard LEDs have a viewing angle of 60deg but others have a narrow beam of 30deg or less
Calculating an LED resistor value
An LED must have a resistor connected in series to limit the current through the LED otherwise it will burn out almost instantly
The resistor value R is given by
R = (VS - VL) I
VS = supply voltage VL = LED voltage (usually 2V but 4V for blue and white LEDs) I = LED current (eg 20mA) this must be less than the maximum permitted
If the calculated value is not available choose the nearest standard resistor value which is greater so that the current will be a little less than you chose In fact you may wish to choose a greater resistor value to reduce the current (to increase battery life for example) but this will make the LED less bright
Working out the LED resistor formula using Ohms law
Ohms law says that the resistance of the resistor R = VI where V = voltage across the resistor (= VS - VL in this case) I = the current through the resistor
So R = (VS - VL) I
BUZZERS
A buzzer or beeper (BUZZERS) is a signalling device usually electronic typically used in automobiles household appliances such as a microwave oven or game shows It most commonly consists of a number of switches or sensors connected to a control unit that determines if and which button was pushed or a preset time has lapsed and usually illuminates a light on the appropriate button or control panel and sounds a warning in the form of a continuous or intermittent buzzing
or beeping sound Initially this device was based on an electromechanical system which was identical to an electric bell without the metal gong (which makes the ringing noise) Often these units were anchored to a wall or ceiling and used the ceiling or wall as a sounding board Another implementation with some AC-connected devices was to implement a circuit to make the AC current into a noise loud enough to drive a loudspeaker and hook this circuit up to a cheap 8-ohm speaker Nowadays it is more popular to use a ceramic-based piezoelectric sounder which makes a high-pitched tone Usually these were hooked up to driver circuits which varied the pitch of the sound or pulsed the sound on and off
The word buzzer comes from the rasping noise that buzzers made when they were electromechanical devices operated from stepped-down AC line voltage at 50 or 60 cycles Other sounds commonly used to indicate that a button has been pressed are a ring or a beep
MOTORS
An electric motor is a device using electrical energy to produce mechanical energy nearly always by the interaction of magnetic fields and current-carrying conductors The reverse process that of using mechanical energy to produce electrical energy is accomplished by a generator or dynamo Traction motors used on vehicles often perform both tasks
Electric motors are found in myriad uses such as industrial fans blowers and pumps machine tools household appliances power tools and computer disk drives among
many other applications Electric motors may be operated by direct current from a battery in a portable device or motor vehicle or from alternating current from a central electrical distribution grid The smallest motors may be found in electric wristwatches Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses The very largest electric motors are used for propulsion of large ships and for such purposes as pipeline compressors with ratings in the thousands of kilowatts Electric motors may be classified by the source of electric power by their internal construction and by application
The physical principle of production of mechanical force by the interaction of an electric current and a magnetic field was known as early as 1821 Electric motors of increasing efficiency were constructed throughout the 19th century but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks
CONNECTORS
A DC connector is an electrical connector for
supplying direct current (DC) power DC connectors
are poorly standardized compared to domestic AC
power plugs and sockets DC plug is a common name
used for one common type of cylindrical two-conductor
plug available in a range of sizes and used to power
small pieces of electronic equipment It is also used to
describe some older multi-pin plugs
Several competing standards exist for DC plugs and in some cases incompatible plugs
will fit together to avoid damaging equipment these conditions must be true
Voltage must match
Polarity is correct
Current ratings are sufficient
Power supply filtering and stability is adequate
for the equipment being powered
Non-matching connectors are forced together
12V DC BATTERY
Features
Less than a 12 volt self discharge per 6 months 4 ea 12Vdc outputs 20 AmpHours Built-charger Digital Voltmeter
Description
This unit supplies a full 12Vdc at 20 AmpHours Designed for the officer that needs a power source that can be charged from 115Ac source or on the way to a incident from the car
The battery source has a very low self discharge rate which makes it perfect for law enforcement use The battery can set on the shelf for more than 6 months without recharging
Everyone knows when you grab a battery operated device the internal battery always requires several hours of charging before using The new voltage indicator reads out voltage to one hundredth of a volt for accurate operation The four outputs are 21mm plug Quick terminals and Cigarette lighter jack amp PT02 (Mil Spec) This model also allows powering
12Vdc sources while plugged in to 115Vac ldquoIts a UPSrdquo
SPECIFICATIONS OF COMPONENTS USED
PLC S7-200
INPUT POWER 230V AC 50 Hz
INPUTS 24 DC INPUTS
OUTPUTS 16 DC OUTPUTS
PROGRAM MEMORY 24
DATA MEMORY 10KB
EXPANSION MODULES 7
COMMUNICATION PORTS 2 RS 485
DIGITAL IO IMAGE SIZE 256(128 in 128 out)
EXECUTION SPEED 022microsecondsinstruction
SENSORS
SENSING RANGE 3mm
HOUSING MATERIAL Brass Nickel Plated
OPERATING VOLTAGE 10-30V
OPERATING CURRENT lt200mA
CONNECTION TYPE Cable
LEDS
DIAMETER 5mm
MAXIMUM VOLTAGE 1V
MAXIMUM CURRENT 10mA
INTENSITY
BUZZERS
OPERATING VOLTAGE30Vp-p
RATED FREQUENCY2000Hz 500Hz
OPERATING TEMP RANGE -20 to 60 degree
SOUND OUTPUT70 dB min10 cm
MOTOR
TOTAL LENGTH 46mm MOTOR DIAMETER 36mm MOTOR LENGTH 25mm DC SUPPLY 4 to 12V RPM 100 BRUSH TYPE Precious metal GEAR HEAD DIAMETER 37mm GEAR HEAD LENGTH 21mm OUTPUT SHAFT Centered SHAFT DIAMETER 4mm and 6mm
SHAFT LENGTH 22mm
- Block diagram of plc
- Applications
-
- Function
- Testing an LED
- Sizes Shapes and Viewing angles of LEDs
- Calculating an LED resistor value
-
- Working out the LED resistor formula using Ohms law
-
S7-200 goes automatically to STOP mode when power is restored If a power cycle occurs when the mode switch is set to RUN the S7-200 goes to RUN mode when power is restored
1048600 STEP 7--MicroWIN allows you to change the operating mode of the online S7-200 To enable the software to change the operating mode you must manually set the mode switch on the S7-200 to either TERM or RUN You can use the PLC gt STOP or PLC gt RUN menu commands or the associated buttons on the toolbar to change the operating mode
1048600 You can insert the STOP instruction in your program to change the S7-200 to STOP mode This allows you to halt the execution of your program based on the program logic
ERRORS IN S7-200
Non-Fatal Errors
Non-fatal errors are those indicating problems with the construction of the user program with the execution of an instruction in the user program and with expansion IO modules You can use STEP 7--MicroWIN to view the error codes that were generated by the non-fatal error There are three basic categories of non-fatal errors
Program-compile errorsThe S7-200 compiles the program as it downloads If the S7-200 detects that the program violates a compilation rule the download is aborted and an error code is generated (A program that was already downloaded to the S7-200 would still exist in the EEPROM and would not be lost) After you correct your program you can download it again
IO errorsAt startup the S7-200 reads the IO configuration from each module During normal operation the S7-200 periodically checks the status of each module and compares it against the configuration obtained during startup If the S7-200 detects a difference the S7-200 sets the configuration error bit in the module error register The S7-200 does not read input data from or write output data to that module until the module configuration again matches the one obtained at startupThe module status information is stored in special memory (SM) bits Your program can monitor and evaluate these bits Refer to Appendix D for more information about the SM bits used for reporting IO errors SM50 is the global IO error bit and remains set while an error condition exists on an expansion module
Program execution errorsYour program can create error conditions while being executed These errors can result from improper use of an instruction or from the processing of invalid data by an instruction For example an indirect-address pointer that was valid when the program compiled could be modified during the execution of the program to point to an out-of-range address This is an example of a run-time programming problem SM43 is setupon the occurrence of a run-time programming problem and remains set while the S7-200 is in RUN mode Program execution error information is stored in special memory (SM) bits Your program can monitor and evaluate these bits The S7-200 does not change to STOP mode when it detects a non-fatal error It only logs the event in SM memory and continues with the execution of your program However you can design your program to force the S7-200 to STOP mode when a non-fatal error is detected
Fatal Errors
Fatal errors cause the S7-200 to stop the execution of your program Depending upon the severity of the fatal error it can render the S7-200 incapable of performing any or all functions The objective for handling fatal errors is to bring the S7-200 to a safe state from which the S7-200 can respond to interrogations about the existing error conditions When a fatal error is detected the S7-200 changes to STOP mode turns on the System Fault LED and the STOP LED overrides the output table and turns off the outputsThe S7-200 remains in this condition until the fatal error condition is corrected
Once you have made the changes to correct the fatal error condition use one of the following methods to restart the S7-200 1048600 Turn the power off and then on 1048600 Change the mode switch from RUN or TERM to STOP 1048600 Select the PLC gt Power-Up Reset menu command from STEP 7--MicroWIN
to restart the S7-200This forces the S7-200 to restart and clear any fatal errors
Restarting the S7-200 clears the fatal error condition and performs power-up diagnostic testing to verify that the fatal error has been corrected If another fatal error condition is found the S7-200 again sets the fault LED indicating that an error still exists Otherwise the S7-200 begins normal operation
Some error conditions can render the S7-200 incapable of communication In these cases you cannot view the error code from the S7-200 These types of errors indicate hardware failures that require the S7-200 to be repaired they cannot be fixed by changes to the program or clearing the memory of the S7-200
APPLICATIONS OF S7-200
Conveyer Systems
Elevators
Test Stations
Placement Systems
Woodworking Machinery
Packaging Equipment
Car Wash Automation
Remote Monitoring And Controlling For Water Wastewater
FEATURES OF LADDER DIAGRAMS
The LAD editor displays the program as a graphical representation similar to electrical wiring diagrams
Ladder programs allow the program to emulate the flow of electric current from a power source through a series of logical input conditions that in turn enable logical output conditions
A LAD program includes a left power rail that is energized Contacts that are closed allow energy to flow through them to the next element and contacts that are open block that energy flow
The logic is separated into networks The program is executed one network at a time from left to right and then top to bottom as dictated by the program Figure shows an example of a LAD program
The various instructions are represented by graphic symbols and include three basic forms
Contacts represent logic input conditions such as switches buttons or internal conditions
Coils usually represent logic output results such as lamps motor starters interposing relays or internal output conditions
Boxes represent additional instructions such as timers counters or math instructions Figure Sample LAD Program
Consider these main points when you select the LAD editor 1048600 Ladder logic is easy for beginning programmers to use 1048600 Graphical representation is easy to understand and is popular around the world 1048600 The LAD editor can be used with both the SIMATIC and IEC 1131--3 Instruction sets
1048600 You can always use the STL editor to display a program created with
the SIMATIC LAD editor
COMPONENTS LIST
Cardboard of 4050 sqcm
PLC S7-200
Sensors
LEDS
Buzzers
Motor
Contactors
Power supply
12v DC battery
Connecting wires
PPI Cable
SENSORS
A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact A proximity sensor often emits an electromagnetic or electrostatic field or a beam of electromagnetic radiation (infrared for instance) and looks for changes in the field or return signal The object being sensed is often referred to as the proximity sensors target Different
proximity sensor targets demand different sensors For example a capacitive or photoelectric sensor might be suitable for a plastic target an inductive proximity sensor requires a metal target
The maximum distance that this sensor can detect is defined nominal range Some sensors have adjustments of the nominal range or means to report a graduated detection distance
Proximity sensors can have a high reliability and long functional life because of the absence of mechanical parts and lack of physical contact between sensor and the sensed object
IEC 60947-5-2 defines the technical details of proximity sensors
A proximity sensor adjusted to a very short range is often used as a touch switch
Applications
Car bumpers that sense distance to nearby cars for parking
Ground proximity warning system for aviation safety Vibration Position measurements of rotating shafts in
machinery Sheet break sensing in paper machine Anti-aircraft artillery
LEDS
Example Circuit symbol
FunctionLEDs emit light when an electric current passes through them
Testing an LED
Never connect an LED directly to a battery or power supply
LEDs must have a resistor in series to limit the current to a safe value for quick testing purposes a 1k resistor is suitable for most LEDs if your supply voltage is 12V or less Remember to connect the LED the correct way round
Sizes Shapes and Viewing angles of LEDs
LEDs are available in a wide variety of sizes and shapes The standard LED has a round cross-section of 5mm diameter and this is probably the best type for general use but 3mm round LEDs are also popular
Round cross-section LEDs are frequently used and they are very easy to install on boxes by drilling a hole of the LED diameter adding a spot of glue will help to hold the LED if necessary LED clips are also available to secure LEDs in holes Other cross-section shapes include square rectangular and triangular
As well as a variety of colours sizes and shapes LEDs also vary in their viewing angle This tells you how much the beam of light spreads out Standard LEDs have a viewing angle of 60deg but others have a narrow beam of 30deg or less
Calculating an LED resistor value
An LED must have a resistor connected in series to limit the current through the LED otherwise it will burn out almost instantly
The resistor value R is given by
R = (VS - VL) I
VS = supply voltage VL = LED voltage (usually 2V but 4V for blue and white LEDs) I = LED current (eg 20mA) this must be less than the maximum permitted
If the calculated value is not available choose the nearest standard resistor value which is greater so that the current will be a little less than you chose In fact you may wish to choose a greater resistor value to reduce the current (to increase battery life for example) but this will make the LED less bright
Working out the LED resistor formula using Ohms law
Ohms law says that the resistance of the resistor R = VI where V = voltage across the resistor (= VS - VL in this case) I = the current through the resistor
So R = (VS - VL) I
BUZZERS
A buzzer or beeper (BUZZERS) is a signalling device usually electronic typically used in automobiles household appliances such as a microwave oven or game shows It most commonly consists of a number of switches or sensors connected to a control unit that determines if and which button was pushed or a preset time has lapsed and usually illuminates a light on the appropriate button or control panel and sounds a warning in the form of a continuous or intermittent buzzing
or beeping sound Initially this device was based on an electromechanical system which was identical to an electric bell without the metal gong (which makes the ringing noise) Often these units were anchored to a wall or ceiling and used the ceiling or wall as a sounding board Another implementation with some AC-connected devices was to implement a circuit to make the AC current into a noise loud enough to drive a loudspeaker and hook this circuit up to a cheap 8-ohm speaker Nowadays it is more popular to use a ceramic-based piezoelectric sounder which makes a high-pitched tone Usually these were hooked up to driver circuits which varied the pitch of the sound or pulsed the sound on and off
The word buzzer comes from the rasping noise that buzzers made when they were electromechanical devices operated from stepped-down AC line voltage at 50 or 60 cycles Other sounds commonly used to indicate that a button has been pressed are a ring or a beep
MOTORS
An electric motor is a device using electrical energy to produce mechanical energy nearly always by the interaction of magnetic fields and current-carrying conductors The reverse process that of using mechanical energy to produce electrical energy is accomplished by a generator or dynamo Traction motors used on vehicles often perform both tasks
Electric motors are found in myriad uses such as industrial fans blowers and pumps machine tools household appliances power tools and computer disk drives among
many other applications Electric motors may be operated by direct current from a battery in a portable device or motor vehicle or from alternating current from a central electrical distribution grid The smallest motors may be found in electric wristwatches Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses The very largest electric motors are used for propulsion of large ships and for such purposes as pipeline compressors with ratings in the thousands of kilowatts Electric motors may be classified by the source of electric power by their internal construction and by application
The physical principle of production of mechanical force by the interaction of an electric current and a magnetic field was known as early as 1821 Electric motors of increasing efficiency were constructed throughout the 19th century but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks
CONNECTORS
A DC connector is an electrical connector for
supplying direct current (DC) power DC connectors
are poorly standardized compared to domestic AC
power plugs and sockets DC plug is a common name
used for one common type of cylindrical two-conductor
plug available in a range of sizes and used to power
small pieces of electronic equipment It is also used to
describe some older multi-pin plugs
Several competing standards exist for DC plugs and in some cases incompatible plugs
will fit together to avoid damaging equipment these conditions must be true
Voltage must match
Polarity is correct
Current ratings are sufficient
Power supply filtering and stability is adequate
for the equipment being powered
Non-matching connectors are forced together
12V DC BATTERY
Features
Less than a 12 volt self discharge per 6 months 4 ea 12Vdc outputs 20 AmpHours Built-charger Digital Voltmeter
Description
This unit supplies a full 12Vdc at 20 AmpHours Designed for the officer that needs a power source that can be charged from 115Ac source or on the way to a incident from the car
The battery source has a very low self discharge rate which makes it perfect for law enforcement use The battery can set on the shelf for more than 6 months without recharging
Everyone knows when you grab a battery operated device the internal battery always requires several hours of charging before using The new voltage indicator reads out voltage to one hundredth of a volt for accurate operation The four outputs are 21mm plug Quick terminals and Cigarette lighter jack amp PT02 (Mil Spec) This model also allows powering
12Vdc sources while plugged in to 115Vac ldquoIts a UPSrdquo
SPECIFICATIONS OF COMPONENTS USED
PLC S7-200
INPUT POWER 230V AC 50 Hz
INPUTS 24 DC INPUTS
OUTPUTS 16 DC OUTPUTS
PROGRAM MEMORY 24
DATA MEMORY 10KB
EXPANSION MODULES 7
COMMUNICATION PORTS 2 RS 485
DIGITAL IO IMAGE SIZE 256(128 in 128 out)
EXECUTION SPEED 022microsecondsinstruction
SENSORS
SENSING RANGE 3mm
HOUSING MATERIAL Brass Nickel Plated
OPERATING VOLTAGE 10-30V
OPERATING CURRENT lt200mA
CONNECTION TYPE Cable
LEDS
DIAMETER 5mm
MAXIMUM VOLTAGE 1V
MAXIMUM CURRENT 10mA
INTENSITY
BUZZERS
OPERATING VOLTAGE30Vp-p
RATED FREQUENCY2000Hz 500Hz
OPERATING TEMP RANGE -20 to 60 degree
SOUND OUTPUT70 dB min10 cm
MOTOR
TOTAL LENGTH 46mm MOTOR DIAMETER 36mm MOTOR LENGTH 25mm DC SUPPLY 4 to 12V RPM 100 BRUSH TYPE Precious metal GEAR HEAD DIAMETER 37mm GEAR HEAD LENGTH 21mm OUTPUT SHAFT Centered SHAFT DIAMETER 4mm and 6mm
SHAFT LENGTH 22mm
- Block diagram of plc
- Applications
-
- Function
- Testing an LED
- Sizes Shapes and Viewing angles of LEDs
- Calculating an LED resistor value
-
- Working out the LED resistor formula using Ohms law
-
IO errorsAt startup the S7-200 reads the IO configuration from each module During normal operation the S7-200 periodically checks the status of each module and compares it against the configuration obtained during startup If the S7-200 detects a difference the S7-200 sets the configuration error bit in the module error register The S7-200 does not read input data from or write output data to that module until the module configuration again matches the one obtained at startupThe module status information is stored in special memory (SM) bits Your program can monitor and evaluate these bits Refer to Appendix D for more information about the SM bits used for reporting IO errors SM50 is the global IO error bit and remains set while an error condition exists on an expansion module
Program execution errorsYour program can create error conditions while being executed These errors can result from improper use of an instruction or from the processing of invalid data by an instruction For example an indirect-address pointer that was valid when the program compiled could be modified during the execution of the program to point to an out-of-range address This is an example of a run-time programming problem SM43 is setupon the occurrence of a run-time programming problem and remains set while the S7-200 is in RUN mode Program execution error information is stored in special memory (SM) bits Your program can monitor and evaluate these bits The S7-200 does not change to STOP mode when it detects a non-fatal error It only logs the event in SM memory and continues with the execution of your program However you can design your program to force the S7-200 to STOP mode when a non-fatal error is detected
Fatal Errors
Fatal errors cause the S7-200 to stop the execution of your program Depending upon the severity of the fatal error it can render the S7-200 incapable of performing any or all functions The objective for handling fatal errors is to bring the S7-200 to a safe state from which the S7-200 can respond to interrogations about the existing error conditions When a fatal error is detected the S7-200 changes to STOP mode turns on the System Fault LED and the STOP LED overrides the output table and turns off the outputsThe S7-200 remains in this condition until the fatal error condition is corrected
Once you have made the changes to correct the fatal error condition use one of the following methods to restart the S7-200 1048600 Turn the power off and then on 1048600 Change the mode switch from RUN or TERM to STOP 1048600 Select the PLC gt Power-Up Reset menu command from STEP 7--MicroWIN
to restart the S7-200This forces the S7-200 to restart and clear any fatal errors
Restarting the S7-200 clears the fatal error condition and performs power-up diagnostic testing to verify that the fatal error has been corrected If another fatal error condition is found the S7-200 again sets the fault LED indicating that an error still exists Otherwise the S7-200 begins normal operation
Some error conditions can render the S7-200 incapable of communication In these cases you cannot view the error code from the S7-200 These types of errors indicate hardware failures that require the S7-200 to be repaired they cannot be fixed by changes to the program or clearing the memory of the S7-200
APPLICATIONS OF S7-200
Conveyer Systems
Elevators
Test Stations
Placement Systems
Woodworking Machinery
Packaging Equipment
Car Wash Automation
Remote Monitoring And Controlling For Water Wastewater
FEATURES OF LADDER DIAGRAMS
The LAD editor displays the program as a graphical representation similar to electrical wiring diagrams
Ladder programs allow the program to emulate the flow of electric current from a power source through a series of logical input conditions that in turn enable logical output conditions
A LAD program includes a left power rail that is energized Contacts that are closed allow energy to flow through them to the next element and contacts that are open block that energy flow
The logic is separated into networks The program is executed one network at a time from left to right and then top to bottom as dictated by the program Figure shows an example of a LAD program
The various instructions are represented by graphic symbols and include three basic forms
Contacts represent logic input conditions such as switches buttons or internal conditions
Coils usually represent logic output results such as lamps motor starters interposing relays or internal output conditions
Boxes represent additional instructions such as timers counters or math instructions Figure Sample LAD Program
Consider these main points when you select the LAD editor 1048600 Ladder logic is easy for beginning programmers to use 1048600 Graphical representation is easy to understand and is popular around the world 1048600 The LAD editor can be used with both the SIMATIC and IEC 1131--3 Instruction sets
1048600 You can always use the STL editor to display a program created with
the SIMATIC LAD editor
COMPONENTS LIST
Cardboard of 4050 sqcm
PLC S7-200
Sensors
LEDS
Buzzers
Motor
Contactors
Power supply
12v DC battery
Connecting wires
PPI Cable
SENSORS
A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact A proximity sensor often emits an electromagnetic or electrostatic field or a beam of electromagnetic radiation (infrared for instance) and looks for changes in the field or return signal The object being sensed is often referred to as the proximity sensors target Different
proximity sensor targets demand different sensors For example a capacitive or photoelectric sensor might be suitable for a plastic target an inductive proximity sensor requires a metal target
The maximum distance that this sensor can detect is defined nominal range Some sensors have adjustments of the nominal range or means to report a graduated detection distance
Proximity sensors can have a high reliability and long functional life because of the absence of mechanical parts and lack of physical contact between sensor and the sensed object
IEC 60947-5-2 defines the technical details of proximity sensors
A proximity sensor adjusted to a very short range is often used as a touch switch
Applications
Car bumpers that sense distance to nearby cars for parking
Ground proximity warning system for aviation safety Vibration Position measurements of rotating shafts in
machinery Sheet break sensing in paper machine Anti-aircraft artillery
LEDS
Example Circuit symbol
FunctionLEDs emit light when an electric current passes through them
Testing an LED
Never connect an LED directly to a battery or power supply
LEDs must have a resistor in series to limit the current to a safe value for quick testing purposes a 1k resistor is suitable for most LEDs if your supply voltage is 12V or less Remember to connect the LED the correct way round
Sizes Shapes and Viewing angles of LEDs
LEDs are available in a wide variety of sizes and shapes The standard LED has a round cross-section of 5mm diameter and this is probably the best type for general use but 3mm round LEDs are also popular
Round cross-section LEDs are frequently used and they are very easy to install on boxes by drilling a hole of the LED diameter adding a spot of glue will help to hold the LED if necessary LED clips are also available to secure LEDs in holes Other cross-section shapes include square rectangular and triangular
As well as a variety of colours sizes and shapes LEDs also vary in their viewing angle This tells you how much the beam of light spreads out Standard LEDs have a viewing angle of 60deg but others have a narrow beam of 30deg or less
Calculating an LED resistor value
An LED must have a resistor connected in series to limit the current through the LED otherwise it will burn out almost instantly
The resistor value R is given by
R = (VS - VL) I
VS = supply voltage VL = LED voltage (usually 2V but 4V for blue and white LEDs) I = LED current (eg 20mA) this must be less than the maximum permitted
If the calculated value is not available choose the nearest standard resistor value which is greater so that the current will be a little less than you chose In fact you may wish to choose a greater resistor value to reduce the current (to increase battery life for example) but this will make the LED less bright
Working out the LED resistor formula using Ohms law
Ohms law says that the resistance of the resistor R = VI where V = voltage across the resistor (= VS - VL in this case) I = the current through the resistor
So R = (VS - VL) I
BUZZERS
A buzzer or beeper (BUZZERS) is a signalling device usually electronic typically used in automobiles household appliances such as a microwave oven or game shows It most commonly consists of a number of switches or sensors connected to a control unit that determines if and which button was pushed or a preset time has lapsed and usually illuminates a light on the appropriate button or control panel and sounds a warning in the form of a continuous or intermittent buzzing
or beeping sound Initially this device was based on an electromechanical system which was identical to an electric bell without the metal gong (which makes the ringing noise) Often these units were anchored to a wall or ceiling and used the ceiling or wall as a sounding board Another implementation with some AC-connected devices was to implement a circuit to make the AC current into a noise loud enough to drive a loudspeaker and hook this circuit up to a cheap 8-ohm speaker Nowadays it is more popular to use a ceramic-based piezoelectric sounder which makes a high-pitched tone Usually these were hooked up to driver circuits which varied the pitch of the sound or pulsed the sound on and off
The word buzzer comes from the rasping noise that buzzers made when they were electromechanical devices operated from stepped-down AC line voltage at 50 or 60 cycles Other sounds commonly used to indicate that a button has been pressed are a ring or a beep
MOTORS
An electric motor is a device using electrical energy to produce mechanical energy nearly always by the interaction of magnetic fields and current-carrying conductors The reverse process that of using mechanical energy to produce electrical energy is accomplished by a generator or dynamo Traction motors used on vehicles often perform both tasks
Electric motors are found in myriad uses such as industrial fans blowers and pumps machine tools household appliances power tools and computer disk drives among
many other applications Electric motors may be operated by direct current from a battery in a portable device or motor vehicle or from alternating current from a central electrical distribution grid The smallest motors may be found in electric wristwatches Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses The very largest electric motors are used for propulsion of large ships and for such purposes as pipeline compressors with ratings in the thousands of kilowatts Electric motors may be classified by the source of electric power by their internal construction and by application
The physical principle of production of mechanical force by the interaction of an electric current and a magnetic field was known as early as 1821 Electric motors of increasing efficiency were constructed throughout the 19th century but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks
CONNECTORS
A DC connector is an electrical connector for
supplying direct current (DC) power DC connectors
are poorly standardized compared to domestic AC
power plugs and sockets DC plug is a common name
used for one common type of cylindrical two-conductor
plug available in a range of sizes and used to power
small pieces of electronic equipment It is also used to
describe some older multi-pin plugs
Several competing standards exist for DC plugs and in some cases incompatible plugs
will fit together to avoid damaging equipment these conditions must be true
Voltage must match
Polarity is correct
Current ratings are sufficient
Power supply filtering and stability is adequate
for the equipment being powered
Non-matching connectors are forced together
12V DC BATTERY
Features
Less than a 12 volt self discharge per 6 months 4 ea 12Vdc outputs 20 AmpHours Built-charger Digital Voltmeter
Description
This unit supplies a full 12Vdc at 20 AmpHours Designed for the officer that needs a power source that can be charged from 115Ac source or on the way to a incident from the car
The battery source has a very low self discharge rate which makes it perfect for law enforcement use The battery can set on the shelf for more than 6 months without recharging
Everyone knows when you grab a battery operated device the internal battery always requires several hours of charging before using The new voltage indicator reads out voltage to one hundredth of a volt for accurate operation The four outputs are 21mm plug Quick terminals and Cigarette lighter jack amp PT02 (Mil Spec) This model also allows powering
12Vdc sources while plugged in to 115Vac ldquoIts a UPSrdquo
SPECIFICATIONS OF COMPONENTS USED
PLC S7-200
INPUT POWER 230V AC 50 Hz
INPUTS 24 DC INPUTS
OUTPUTS 16 DC OUTPUTS
PROGRAM MEMORY 24
DATA MEMORY 10KB
EXPANSION MODULES 7
COMMUNICATION PORTS 2 RS 485
DIGITAL IO IMAGE SIZE 256(128 in 128 out)
EXECUTION SPEED 022microsecondsinstruction
SENSORS
SENSING RANGE 3mm
HOUSING MATERIAL Brass Nickel Plated
OPERATING VOLTAGE 10-30V
OPERATING CURRENT lt200mA
CONNECTION TYPE Cable
LEDS
DIAMETER 5mm
MAXIMUM VOLTAGE 1V
MAXIMUM CURRENT 10mA
INTENSITY
BUZZERS
OPERATING VOLTAGE30Vp-p
RATED FREQUENCY2000Hz 500Hz
OPERATING TEMP RANGE -20 to 60 degree
SOUND OUTPUT70 dB min10 cm
MOTOR
TOTAL LENGTH 46mm MOTOR DIAMETER 36mm MOTOR LENGTH 25mm DC SUPPLY 4 to 12V RPM 100 BRUSH TYPE Precious metal GEAR HEAD DIAMETER 37mm GEAR HEAD LENGTH 21mm OUTPUT SHAFT Centered SHAFT DIAMETER 4mm and 6mm
SHAFT LENGTH 22mm
- Block diagram of plc
- Applications
-
- Function
- Testing an LED
- Sizes Shapes and Viewing angles of LEDs
- Calculating an LED resistor value
-
- Working out the LED resistor formula using Ohms law
-
to restart the S7-200This forces the S7-200 to restart and clear any fatal errors
Restarting the S7-200 clears the fatal error condition and performs power-up diagnostic testing to verify that the fatal error has been corrected If another fatal error condition is found the S7-200 again sets the fault LED indicating that an error still exists Otherwise the S7-200 begins normal operation
Some error conditions can render the S7-200 incapable of communication In these cases you cannot view the error code from the S7-200 These types of errors indicate hardware failures that require the S7-200 to be repaired they cannot be fixed by changes to the program or clearing the memory of the S7-200
APPLICATIONS OF S7-200
Conveyer Systems
Elevators
Test Stations
Placement Systems
Woodworking Machinery
Packaging Equipment
Car Wash Automation
Remote Monitoring And Controlling For Water Wastewater
FEATURES OF LADDER DIAGRAMS
The LAD editor displays the program as a graphical representation similar to electrical wiring diagrams
Ladder programs allow the program to emulate the flow of electric current from a power source through a series of logical input conditions that in turn enable logical output conditions
A LAD program includes a left power rail that is energized Contacts that are closed allow energy to flow through them to the next element and contacts that are open block that energy flow
The logic is separated into networks The program is executed one network at a time from left to right and then top to bottom as dictated by the program Figure shows an example of a LAD program
The various instructions are represented by graphic symbols and include three basic forms
Contacts represent logic input conditions such as switches buttons or internal conditions
Coils usually represent logic output results such as lamps motor starters interposing relays or internal output conditions
Boxes represent additional instructions such as timers counters or math instructions Figure Sample LAD Program
Consider these main points when you select the LAD editor 1048600 Ladder logic is easy for beginning programmers to use 1048600 Graphical representation is easy to understand and is popular around the world 1048600 The LAD editor can be used with both the SIMATIC and IEC 1131--3 Instruction sets
1048600 You can always use the STL editor to display a program created with
the SIMATIC LAD editor
COMPONENTS LIST
Cardboard of 4050 sqcm
PLC S7-200
Sensors
LEDS
Buzzers
Motor
Contactors
Power supply
12v DC battery
Connecting wires
PPI Cable
SENSORS
A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact A proximity sensor often emits an electromagnetic or electrostatic field or a beam of electromagnetic radiation (infrared for instance) and looks for changes in the field or return signal The object being sensed is often referred to as the proximity sensors target Different
proximity sensor targets demand different sensors For example a capacitive or photoelectric sensor might be suitable for a plastic target an inductive proximity sensor requires a metal target
The maximum distance that this sensor can detect is defined nominal range Some sensors have adjustments of the nominal range or means to report a graduated detection distance
Proximity sensors can have a high reliability and long functional life because of the absence of mechanical parts and lack of physical contact between sensor and the sensed object
IEC 60947-5-2 defines the technical details of proximity sensors
A proximity sensor adjusted to a very short range is often used as a touch switch
Applications
Car bumpers that sense distance to nearby cars for parking
Ground proximity warning system for aviation safety Vibration Position measurements of rotating shafts in
machinery Sheet break sensing in paper machine Anti-aircraft artillery
LEDS
Example Circuit symbol
FunctionLEDs emit light when an electric current passes through them
Testing an LED
Never connect an LED directly to a battery or power supply
LEDs must have a resistor in series to limit the current to a safe value for quick testing purposes a 1k resistor is suitable for most LEDs if your supply voltage is 12V or less Remember to connect the LED the correct way round
Sizes Shapes and Viewing angles of LEDs
LEDs are available in a wide variety of sizes and shapes The standard LED has a round cross-section of 5mm diameter and this is probably the best type for general use but 3mm round LEDs are also popular
Round cross-section LEDs are frequently used and they are very easy to install on boxes by drilling a hole of the LED diameter adding a spot of glue will help to hold the LED if necessary LED clips are also available to secure LEDs in holes Other cross-section shapes include square rectangular and triangular
As well as a variety of colours sizes and shapes LEDs also vary in their viewing angle This tells you how much the beam of light spreads out Standard LEDs have a viewing angle of 60deg but others have a narrow beam of 30deg or less
Calculating an LED resistor value
An LED must have a resistor connected in series to limit the current through the LED otherwise it will burn out almost instantly
The resistor value R is given by
R = (VS - VL) I
VS = supply voltage VL = LED voltage (usually 2V but 4V for blue and white LEDs) I = LED current (eg 20mA) this must be less than the maximum permitted
If the calculated value is not available choose the nearest standard resistor value which is greater so that the current will be a little less than you chose In fact you may wish to choose a greater resistor value to reduce the current (to increase battery life for example) but this will make the LED less bright
Working out the LED resistor formula using Ohms law
Ohms law says that the resistance of the resistor R = VI where V = voltage across the resistor (= VS - VL in this case) I = the current through the resistor
So R = (VS - VL) I
BUZZERS
A buzzer or beeper (BUZZERS) is a signalling device usually electronic typically used in automobiles household appliances such as a microwave oven or game shows It most commonly consists of a number of switches or sensors connected to a control unit that determines if and which button was pushed or a preset time has lapsed and usually illuminates a light on the appropriate button or control panel and sounds a warning in the form of a continuous or intermittent buzzing
or beeping sound Initially this device was based on an electromechanical system which was identical to an electric bell without the metal gong (which makes the ringing noise) Often these units were anchored to a wall or ceiling and used the ceiling or wall as a sounding board Another implementation with some AC-connected devices was to implement a circuit to make the AC current into a noise loud enough to drive a loudspeaker and hook this circuit up to a cheap 8-ohm speaker Nowadays it is more popular to use a ceramic-based piezoelectric sounder which makes a high-pitched tone Usually these were hooked up to driver circuits which varied the pitch of the sound or pulsed the sound on and off
The word buzzer comes from the rasping noise that buzzers made when they were electromechanical devices operated from stepped-down AC line voltage at 50 or 60 cycles Other sounds commonly used to indicate that a button has been pressed are a ring or a beep
MOTORS
An electric motor is a device using electrical energy to produce mechanical energy nearly always by the interaction of magnetic fields and current-carrying conductors The reverse process that of using mechanical energy to produce electrical energy is accomplished by a generator or dynamo Traction motors used on vehicles often perform both tasks
Electric motors are found in myriad uses such as industrial fans blowers and pumps machine tools household appliances power tools and computer disk drives among
many other applications Electric motors may be operated by direct current from a battery in a portable device or motor vehicle or from alternating current from a central electrical distribution grid The smallest motors may be found in electric wristwatches Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses The very largest electric motors are used for propulsion of large ships and for such purposes as pipeline compressors with ratings in the thousands of kilowatts Electric motors may be classified by the source of electric power by their internal construction and by application
The physical principle of production of mechanical force by the interaction of an electric current and a magnetic field was known as early as 1821 Electric motors of increasing efficiency were constructed throughout the 19th century but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks
CONNECTORS
A DC connector is an electrical connector for
supplying direct current (DC) power DC connectors
are poorly standardized compared to domestic AC
power plugs and sockets DC plug is a common name
used for one common type of cylindrical two-conductor
plug available in a range of sizes and used to power
small pieces of electronic equipment It is also used to
describe some older multi-pin plugs
Several competing standards exist for DC plugs and in some cases incompatible plugs
will fit together to avoid damaging equipment these conditions must be true
Voltage must match
Polarity is correct
Current ratings are sufficient
Power supply filtering and stability is adequate
for the equipment being powered
Non-matching connectors are forced together
12V DC BATTERY
Features
Less than a 12 volt self discharge per 6 months 4 ea 12Vdc outputs 20 AmpHours Built-charger Digital Voltmeter
Description
This unit supplies a full 12Vdc at 20 AmpHours Designed for the officer that needs a power source that can be charged from 115Ac source or on the way to a incident from the car
The battery source has a very low self discharge rate which makes it perfect for law enforcement use The battery can set on the shelf for more than 6 months without recharging
Everyone knows when you grab a battery operated device the internal battery always requires several hours of charging before using The new voltage indicator reads out voltage to one hundredth of a volt for accurate operation The four outputs are 21mm plug Quick terminals and Cigarette lighter jack amp PT02 (Mil Spec) This model also allows powering
12Vdc sources while plugged in to 115Vac ldquoIts a UPSrdquo
SPECIFICATIONS OF COMPONENTS USED
PLC S7-200
INPUT POWER 230V AC 50 Hz
INPUTS 24 DC INPUTS
OUTPUTS 16 DC OUTPUTS
PROGRAM MEMORY 24
DATA MEMORY 10KB
EXPANSION MODULES 7
COMMUNICATION PORTS 2 RS 485
DIGITAL IO IMAGE SIZE 256(128 in 128 out)
EXECUTION SPEED 022microsecondsinstruction
SENSORS
SENSING RANGE 3mm
HOUSING MATERIAL Brass Nickel Plated
OPERATING VOLTAGE 10-30V
OPERATING CURRENT lt200mA
CONNECTION TYPE Cable
LEDS
DIAMETER 5mm
MAXIMUM VOLTAGE 1V
MAXIMUM CURRENT 10mA
INTENSITY
BUZZERS
OPERATING VOLTAGE30Vp-p
RATED FREQUENCY2000Hz 500Hz
OPERATING TEMP RANGE -20 to 60 degree
SOUND OUTPUT70 dB min10 cm
MOTOR
TOTAL LENGTH 46mm MOTOR DIAMETER 36mm MOTOR LENGTH 25mm DC SUPPLY 4 to 12V RPM 100 BRUSH TYPE Precious metal GEAR HEAD DIAMETER 37mm GEAR HEAD LENGTH 21mm OUTPUT SHAFT Centered SHAFT DIAMETER 4mm and 6mm
SHAFT LENGTH 22mm
- Block diagram of plc
- Applications
-
- Function
- Testing an LED
- Sizes Shapes and Viewing angles of LEDs
- Calculating an LED resistor value
-
- Working out the LED resistor formula using Ohms law
-
Packaging Equipment
Car Wash Automation
Remote Monitoring And Controlling For Water Wastewater
FEATURES OF LADDER DIAGRAMS
The LAD editor displays the program as a graphical representation similar to electrical wiring diagrams
Ladder programs allow the program to emulate the flow of electric current from a power source through a series of logical input conditions that in turn enable logical output conditions
A LAD program includes a left power rail that is energized Contacts that are closed allow energy to flow through them to the next element and contacts that are open block that energy flow
The logic is separated into networks The program is executed one network at a time from left to right and then top to bottom as dictated by the program Figure shows an example of a LAD program
The various instructions are represented by graphic symbols and include three basic forms
Contacts represent logic input conditions such as switches buttons or internal conditions
Coils usually represent logic output results such as lamps motor starters interposing relays or internal output conditions
Boxes represent additional instructions such as timers counters or math instructions Figure Sample LAD Program
Consider these main points when you select the LAD editor 1048600 Ladder logic is easy for beginning programmers to use 1048600 Graphical representation is easy to understand and is popular around the world 1048600 The LAD editor can be used with both the SIMATIC and IEC 1131--3 Instruction sets
1048600 You can always use the STL editor to display a program created with
the SIMATIC LAD editor
COMPONENTS LIST
Cardboard of 4050 sqcm
PLC S7-200
Sensors
LEDS
Buzzers
Motor
Contactors
Power supply
12v DC battery
Connecting wires
PPI Cable
SENSORS
A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact A proximity sensor often emits an electromagnetic or electrostatic field or a beam of electromagnetic radiation (infrared for instance) and looks for changes in the field or return signal The object being sensed is often referred to as the proximity sensors target Different
proximity sensor targets demand different sensors For example a capacitive or photoelectric sensor might be suitable for a plastic target an inductive proximity sensor requires a metal target
The maximum distance that this sensor can detect is defined nominal range Some sensors have adjustments of the nominal range or means to report a graduated detection distance
Proximity sensors can have a high reliability and long functional life because of the absence of mechanical parts and lack of physical contact between sensor and the sensed object
IEC 60947-5-2 defines the technical details of proximity sensors
A proximity sensor adjusted to a very short range is often used as a touch switch
Applications
Car bumpers that sense distance to nearby cars for parking
Ground proximity warning system for aviation safety Vibration Position measurements of rotating shafts in
machinery Sheet break sensing in paper machine Anti-aircraft artillery
LEDS
Example Circuit symbol
FunctionLEDs emit light when an electric current passes through them
Testing an LED
Never connect an LED directly to a battery or power supply
LEDs must have a resistor in series to limit the current to a safe value for quick testing purposes a 1k resistor is suitable for most LEDs if your supply voltage is 12V or less Remember to connect the LED the correct way round
Sizes Shapes and Viewing angles of LEDs
LEDs are available in a wide variety of sizes and shapes The standard LED has a round cross-section of 5mm diameter and this is probably the best type for general use but 3mm round LEDs are also popular
Round cross-section LEDs are frequently used and they are very easy to install on boxes by drilling a hole of the LED diameter adding a spot of glue will help to hold the LED if necessary LED clips are also available to secure LEDs in holes Other cross-section shapes include square rectangular and triangular
As well as a variety of colours sizes and shapes LEDs also vary in their viewing angle This tells you how much the beam of light spreads out Standard LEDs have a viewing angle of 60deg but others have a narrow beam of 30deg or less
Calculating an LED resistor value
An LED must have a resistor connected in series to limit the current through the LED otherwise it will burn out almost instantly
The resistor value R is given by
R = (VS - VL) I
VS = supply voltage VL = LED voltage (usually 2V but 4V for blue and white LEDs) I = LED current (eg 20mA) this must be less than the maximum permitted
If the calculated value is not available choose the nearest standard resistor value which is greater so that the current will be a little less than you chose In fact you may wish to choose a greater resistor value to reduce the current (to increase battery life for example) but this will make the LED less bright
Working out the LED resistor formula using Ohms law
Ohms law says that the resistance of the resistor R = VI where V = voltage across the resistor (= VS - VL in this case) I = the current through the resistor
So R = (VS - VL) I
BUZZERS
A buzzer or beeper (BUZZERS) is a signalling device usually electronic typically used in automobiles household appliances such as a microwave oven or game shows It most commonly consists of a number of switches or sensors connected to a control unit that determines if and which button was pushed or a preset time has lapsed and usually illuminates a light on the appropriate button or control panel and sounds a warning in the form of a continuous or intermittent buzzing
or beeping sound Initially this device was based on an electromechanical system which was identical to an electric bell without the metal gong (which makes the ringing noise) Often these units were anchored to a wall or ceiling and used the ceiling or wall as a sounding board Another implementation with some AC-connected devices was to implement a circuit to make the AC current into a noise loud enough to drive a loudspeaker and hook this circuit up to a cheap 8-ohm speaker Nowadays it is more popular to use a ceramic-based piezoelectric sounder which makes a high-pitched tone Usually these were hooked up to driver circuits which varied the pitch of the sound or pulsed the sound on and off
The word buzzer comes from the rasping noise that buzzers made when they were electromechanical devices operated from stepped-down AC line voltage at 50 or 60 cycles Other sounds commonly used to indicate that a button has been pressed are a ring or a beep
MOTORS
An electric motor is a device using electrical energy to produce mechanical energy nearly always by the interaction of magnetic fields and current-carrying conductors The reverse process that of using mechanical energy to produce electrical energy is accomplished by a generator or dynamo Traction motors used on vehicles often perform both tasks
Electric motors are found in myriad uses such as industrial fans blowers and pumps machine tools household appliances power tools and computer disk drives among
many other applications Electric motors may be operated by direct current from a battery in a portable device or motor vehicle or from alternating current from a central electrical distribution grid The smallest motors may be found in electric wristwatches Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses The very largest electric motors are used for propulsion of large ships and for such purposes as pipeline compressors with ratings in the thousands of kilowatts Electric motors may be classified by the source of electric power by their internal construction and by application
The physical principle of production of mechanical force by the interaction of an electric current and a magnetic field was known as early as 1821 Electric motors of increasing efficiency were constructed throughout the 19th century but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks
CONNECTORS
A DC connector is an electrical connector for
supplying direct current (DC) power DC connectors
are poorly standardized compared to domestic AC
power plugs and sockets DC plug is a common name
used for one common type of cylindrical two-conductor
plug available in a range of sizes and used to power
small pieces of electronic equipment It is also used to
describe some older multi-pin plugs
Several competing standards exist for DC plugs and in some cases incompatible plugs
will fit together to avoid damaging equipment these conditions must be true
Voltage must match
Polarity is correct
Current ratings are sufficient
Power supply filtering and stability is adequate
for the equipment being powered
Non-matching connectors are forced together
12V DC BATTERY
Features
Less than a 12 volt self discharge per 6 months 4 ea 12Vdc outputs 20 AmpHours Built-charger Digital Voltmeter
Description
This unit supplies a full 12Vdc at 20 AmpHours Designed for the officer that needs a power source that can be charged from 115Ac source or on the way to a incident from the car
The battery source has a very low self discharge rate which makes it perfect for law enforcement use The battery can set on the shelf for more than 6 months without recharging
Everyone knows when you grab a battery operated device the internal battery always requires several hours of charging before using The new voltage indicator reads out voltage to one hundredth of a volt for accurate operation The four outputs are 21mm plug Quick terminals and Cigarette lighter jack amp PT02 (Mil Spec) This model also allows powering
12Vdc sources while plugged in to 115Vac ldquoIts a UPSrdquo
SPECIFICATIONS OF COMPONENTS USED
PLC S7-200
INPUT POWER 230V AC 50 Hz
INPUTS 24 DC INPUTS
OUTPUTS 16 DC OUTPUTS
PROGRAM MEMORY 24
DATA MEMORY 10KB
EXPANSION MODULES 7
COMMUNICATION PORTS 2 RS 485
DIGITAL IO IMAGE SIZE 256(128 in 128 out)
EXECUTION SPEED 022microsecondsinstruction
SENSORS
SENSING RANGE 3mm
HOUSING MATERIAL Brass Nickel Plated
OPERATING VOLTAGE 10-30V
OPERATING CURRENT lt200mA
CONNECTION TYPE Cable
LEDS
DIAMETER 5mm
MAXIMUM VOLTAGE 1V
MAXIMUM CURRENT 10mA
INTENSITY
BUZZERS
OPERATING VOLTAGE30Vp-p
RATED FREQUENCY2000Hz 500Hz
OPERATING TEMP RANGE -20 to 60 degree
SOUND OUTPUT70 dB min10 cm
MOTOR
TOTAL LENGTH 46mm MOTOR DIAMETER 36mm MOTOR LENGTH 25mm DC SUPPLY 4 to 12V RPM 100 BRUSH TYPE Precious metal GEAR HEAD DIAMETER 37mm GEAR HEAD LENGTH 21mm OUTPUT SHAFT Centered SHAFT DIAMETER 4mm and 6mm
SHAFT LENGTH 22mm
- Block diagram of plc
- Applications
-
- Function
- Testing an LED
- Sizes Shapes and Viewing angles of LEDs
- Calculating an LED resistor value
-
- Working out the LED resistor formula using Ohms law
-
The various instructions are represented by graphic symbols and include three basic forms
Contacts represent logic input conditions such as switches buttons or internal conditions
Coils usually represent logic output results such as lamps motor starters interposing relays or internal output conditions
Boxes represent additional instructions such as timers counters or math instructions Figure Sample LAD Program
Consider these main points when you select the LAD editor 1048600 Ladder logic is easy for beginning programmers to use 1048600 Graphical representation is easy to understand and is popular around the world 1048600 The LAD editor can be used with both the SIMATIC and IEC 1131--3 Instruction sets
1048600 You can always use the STL editor to display a program created with
the SIMATIC LAD editor
COMPONENTS LIST
Cardboard of 4050 sqcm
PLC S7-200
Sensors
LEDS
Buzzers
Motor
Contactors
Power supply
12v DC battery
Connecting wires
PPI Cable
SENSORS
A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact A proximity sensor often emits an electromagnetic or electrostatic field or a beam of electromagnetic radiation (infrared for instance) and looks for changes in the field or return signal The object being sensed is often referred to as the proximity sensors target Different
proximity sensor targets demand different sensors For example a capacitive or photoelectric sensor might be suitable for a plastic target an inductive proximity sensor requires a metal target
The maximum distance that this sensor can detect is defined nominal range Some sensors have adjustments of the nominal range or means to report a graduated detection distance
Proximity sensors can have a high reliability and long functional life because of the absence of mechanical parts and lack of physical contact between sensor and the sensed object
IEC 60947-5-2 defines the technical details of proximity sensors
A proximity sensor adjusted to a very short range is often used as a touch switch
Applications
Car bumpers that sense distance to nearby cars for parking
Ground proximity warning system for aviation safety Vibration Position measurements of rotating shafts in
machinery Sheet break sensing in paper machine Anti-aircraft artillery
LEDS
Example Circuit symbol
FunctionLEDs emit light when an electric current passes through them
Testing an LED
Never connect an LED directly to a battery or power supply
LEDs must have a resistor in series to limit the current to a safe value for quick testing purposes a 1k resistor is suitable for most LEDs if your supply voltage is 12V or less Remember to connect the LED the correct way round
Sizes Shapes and Viewing angles of LEDs
LEDs are available in a wide variety of sizes and shapes The standard LED has a round cross-section of 5mm diameter and this is probably the best type for general use but 3mm round LEDs are also popular
Round cross-section LEDs are frequently used and they are very easy to install on boxes by drilling a hole of the LED diameter adding a spot of glue will help to hold the LED if necessary LED clips are also available to secure LEDs in holes Other cross-section shapes include square rectangular and triangular
As well as a variety of colours sizes and shapes LEDs also vary in their viewing angle This tells you how much the beam of light spreads out Standard LEDs have a viewing angle of 60deg but others have a narrow beam of 30deg or less
Calculating an LED resistor value
An LED must have a resistor connected in series to limit the current through the LED otherwise it will burn out almost instantly
The resistor value R is given by
R = (VS - VL) I
VS = supply voltage VL = LED voltage (usually 2V but 4V for blue and white LEDs) I = LED current (eg 20mA) this must be less than the maximum permitted
If the calculated value is not available choose the nearest standard resistor value which is greater so that the current will be a little less than you chose In fact you may wish to choose a greater resistor value to reduce the current (to increase battery life for example) but this will make the LED less bright
Working out the LED resistor formula using Ohms law
Ohms law says that the resistance of the resistor R = VI where V = voltage across the resistor (= VS - VL in this case) I = the current through the resistor
So R = (VS - VL) I
BUZZERS
A buzzer or beeper (BUZZERS) is a signalling device usually electronic typically used in automobiles household appliances such as a microwave oven or game shows It most commonly consists of a number of switches or sensors connected to a control unit that determines if and which button was pushed or a preset time has lapsed and usually illuminates a light on the appropriate button or control panel and sounds a warning in the form of a continuous or intermittent buzzing
or beeping sound Initially this device was based on an electromechanical system which was identical to an electric bell without the metal gong (which makes the ringing noise) Often these units were anchored to a wall or ceiling and used the ceiling or wall as a sounding board Another implementation with some AC-connected devices was to implement a circuit to make the AC current into a noise loud enough to drive a loudspeaker and hook this circuit up to a cheap 8-ohm speaker Nowadays it is more popular to use a ceramic-based piezoelectric sounder which makes a high-pitched tone Usually these were hooked up to driver circuits which varied the pitch of the sound or pulsed the sound on and off
The word buzzer comes from the rasping noise that buzzers made when they were electromechanical devices operated from stepped-down AC line voltage at 50 or 60 cycles Other sounds commonly used to indicate that a button has been pressed are a ring or a beep
MOTORS
An electric motor is a device using electrical energy to produce mechanical energy nearly always by the interaction of magnetic fields and current-carrying conductors The reverse process that of using mechanical energy to produce electrical energy is accomplished by a generator or dynamo Traction motors used on vehicles often perform both tasks
Electric motors are found in myriad uses such as industrial fans blowers and pumps machine tools household appliances power tools and computer disk drives among
many other applications Electric motors may be operated by direct current from a battery in a portable device or motor vehicle or from alternating current from a central electrical distribution grid The smallest motors may be found in electric wristwatches Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses The very largest electric motors are used for propulsion of large ships and for such purposes as pipeline compressors with ratings in the thousands of kilowatts Electric motors may be classified by the source of electric power by their internal construction and by application
The physical principle of production of mechanical force by the interaction of an electric current and a magnetic field was known as early as 1821 Electric motors of increasing efficiency were constructed throughout the 19th century but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks
CONNECTORS
A DC connector is an electrical connector for
supplying direct current (DC) power DC connectors
are poorly standardized compared to domestic AC
power plugs and sockets DC plug is a common name
used for one common type of cylindrical two-conductor
plug available in a range of sizes and used to power
small pieces of electronic equipment It is also used to
describe some older multi-pin plugs
Several competing standards exist for DC plugs and in some cases incompatible plugs
will fit together to avoid damaging equipment these conditions must be true
Voltage must match
Polarity is correct
Current ratings are sufficient
Power supply filtering and stability is adequate
for the equipment being powered
Non-matching connectors are forced together
12V DC BATTERY
Features
Less than a 12 volt self discharge per 6 months 4 ea 12Vdc outputs 20 AmpHours Built-charger Digital Voltmeter
Description
This unit supplies a full 12Vdc at 20 AmpHours Designed for the officer that needs a power source that can be charged from 115Ac source or on the way to a incident from the car
The battery source has a very low self discharge rate which makes it perfect for law enforcement use The battery can set on the shelf for more than 6 months without recharging
Everyone knows when you grab a battery operated device the internal battery always requires several hours of charging before using The new voltage indicator reads out voltage to one hundredth of a volt for accurate operation The four outputs are 21mm plug Quick terminals and Cigarette lighter jack amp PT02 (Mil Spec) This model also allows powering
12Vdc sources while plugged in to 115Vac ldquoIts a UPSrdquo
SPECIFICATIONS OF COMPONENTS USED
PLC S7-200
INPUT POWER 230V AC 50 Hz
INPUTS 24 DC INPUTS
OUTPUTS 16 DC OUTPUTS
PROGRAM MEMORY 24
DATA MEMORY 10KB
EXPANSION MODULES 7
COMMUNICATION PORTS 2 RS 485
DIGITAL IO IMAGE SIZE 256(128 in 128 out)
EXECUTION SPEED 022microsecondsinstruction
SENSORS
SENSING RANGE 3mm
HOUSING MATERIAL Brass Nickel Plated
OPERATING VOLTAGE 10-30V
OPERATING CURRENT lt200mA
CONNECTION TYPE Cable
LEDS
DIAMETER 5mm
MAXIMUM VOLTAGE 1V
MAXIMUM CURRENT 10mA
INTENSITY
BUZZERS
OPERATING VOLTAGE30Vp-p
RATED FREQUENCY2000Hz 500Hz
OPERATING TEMP RANGE -20 to 60 degree
SOUND OUTPUT70 dB min10 cm
MOTOR
TOTAL LENGTH 46mm MOTOR DIAMETER 36mm MOTOR LENGTH 25mm DC SUPPLY 4 to 12V RPM 100 BRUSH TYPE Precious metal GEAR HEAD DIAMETER 37mm GEAR HEAD LENGTH 21mm OUTPUT SHAFT Centered SHAFT DIAMETER 4mm and 6mm
SHAFT LENGTH 22mm
- Block diagram of plc
- Applications
-
- Function
- Testing an LED
- Sizes Shapes and Viewing angles of LEDs
- Calculating an LED resistor value
-
- Working out the LED resistor formula using Ohms law
-
LEDS
Buzzers
Motor
Contactors
Power supply
12v DC battery
Connecting wires
PPI Cable
SENSORS
A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact A proximity sensor often emits an electromagnetic or electrostatic field or a beam of electromagnetic radiation (infrared for instance) and looks for changes in the field or return signal The object being sensed is often referred to as the proximity sensors target Different
proximity sensor targets demand different sensors For example a capacitive or photoelectric sensor might be suitable for a plastic target an inductive proximity sensor requires a metal target
The maximum distance that this sensor can detect is defined nominal range Some sensors have adjustments of the nominal range or means to report a graduated detection distance
Proximity sensors can have a high reliability and long functional life because of the absence of mechanical parts and lack of physical contact between sensor and the sensed object
IEC 60947-5-2 defines the technical details of proximity sensors
A proximity sensor adjusted to a very short range is often used as a touch switch
Applications
Car bumpers that sense distance to nearby cars for parking
Ground proximity warning system for aviation safety Vibration Position measurements of rotating shafts in
machinery Sheet break sensing in paper machine Anti-aircraft artillery
LEDS
Example Circuit symbol
FunctionLEDs emit light when an electric current passes through them
Testing an LED
Never connect an LED directly to a battery or power supply
LEDs must have a resistor in series to limit the current to a safe value for quick testing purposes a 1k resistor is suitable for most LEDs if your supply voltage is 12V or less Remember to connect the LED the correct way round
Sizes Shapes and Viewing angles of LEDs
LEDs are available in a wide variety of sizes and shapes The standard LED has a round cross-section of 5mm diameter and this is probably the best type for general use but 3mm round LEDs are also popular
Round cross-section LEDs are frequently used and they are very easy to install on boxes by drilling a hole of the LED diameter adding a spot of glue will help to hold the LED if necessary LED clips are also available to secure LEDs in holes Other cross-section shapes include square rectangular and triangular
As well as a variety of colours sizes and shapes LEDs also vary in their viewing angle This tells you how much the beam of light spreads out Standard LEDs have a viewing angle of 60deg but others have a narrow beam of 30deg or less
Calculating an LED resistor value
An LED must have a resistor connected in series to limit the current through the LED otherwise it will burn out almost instantly
The resistor value R is given by
R = (VS - VL) I
VS = supply voltage VL = LED voltage (usually 2V but 4V for blue and white LEDs) I = LED current (eg 20mA) this must be less than the maximum permitted
If the calculated value is not available choose the nearest standard resistor value which is greater so that the current will be a little less than you chose In fact you may wish to choose a greater resistor value to reduce the current (to increase battery life for example) but this will make the LED less bright
Working out the LED resistor formula using Ohms law
Ohms law says that the resistance of the resistor R = VI where V = voltage across the resistor (= VS - VL in this case) I = the current through the resistor
So R = (VS - VL) I
BUZZERS
A buzzer or beeper (BUZZERS) is a signalling device usually electronic typically used in automobiles household appliances such as a microwave oven or game shows It most commonly consists of a number of switches or sensors connected to a control unit that determines if and which button was pushed or a preset time has lapsed and usually illuminates a light on the appropriate button or control panel and sounds a warning in the form of a continuous or intermittent buzzing
or beeping sound Initially this device was based on an electromechanical system which was identical to an electric bell without the metal gong (which makes the ringing noise) Often these units were anchored to a wall or ceiling and used the ceiling or wall as a sounding board Another implementation with some AC-connected devices was to implement a circuit to make the AC current into a noise loud enough to drive a loudspeaker and hook this circuit up to a cheap 8-ohm speaker Nowadays it is more popular to use a ceramic-based piezoelectric sounder which makes a high-pitched tone Usually these were hooked up to driver circuits which varied the pitch of the sound or pulsed the sound on and off
The word buzzer comes from the rasping noise that buzzers made when they were electromechanical devices operated from stepped-down AC line voltage at 50 or 60 cycles Other sounds commonly used to indicate that a button has been pressed are a ring or a beep
MOTORS
An electric motor is a device using electrical energy to produce mechanical energy nearly always by the interaction of magnetic fields and current-carrying conductors The reverse process that of using mechanical energy to produce electrical energy is accomplished by a generator or dynamo Traction motors used on vehicles often perform both tasks
Electric motors are found in myriad uses such as industrial fans blowers and pumps machine tools household appliances power tools and computer disk drives among
many other applications Electric motors may be operated by direct current from a battery in a portable device or motor vehicle or from alternating current from a central electrical distribution grid The smallest motors may be found in electric wristwatches Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses The very largest electric motors are used for propulsion of large ships and for such purposes as pipeline compressors with ratings in the thousands of kilowatts Electric motors may be classified by the source of electric power by their internal construction and by application
The physical principle of production of mechanical force by the interaction of an electric current and a magnetic field was known as early as 1821 Electric motors of increasing efficiency were constructed throughout the 19th century but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks
CONNECTORS
A DC connector is an electrical connector for
supplying direct current (DC) power DC connectors
are poorly standardized compared to domestic AC
power plugs and sockets DC plug is a common name
used for one common type of cylindrical two-conductor
plug available in a range of sizes and used to power
small pieces of electronic equipment It is also used to
describe some older multi-pin plugs
Several competing standards exist for DC plugs and in some cases incompatible plugs
will fit together to avoid damaging equipment these conditions must be true
Voltage must match
Polarity is correct
Current ratings are sufficient
Power supply filtering and stability is adequate
for the equipment being powered
Non-matching connectors are forced together
12V DC BATTERY
Features
Less than a 12 volt self discharge per 6 months 4 ea 12Vdc outputs 20 AmpHours Built-charger Digital Voltmeter
Description
This unit supplies a full 12Vdc at 20 AmpHours Designed for the officer that needs a power source that can be charged from 115Ac source or on the way to a incident from the car
The battery source has a very low self discharge rate which makes it perfect for law enforcement use The battery can set on the shelf for more than 6 months without recharging
Everyone knows when you grab a battery operated device the internal battery always requires several hours of charging before using The new voltage indicator reads out voltage to one hundredth of a volt for accurate operation The four outputs are 21mm plug Quick terminals and Cigarette lighter jack amp PT02 (Mil Spec) This model also allows powering
12Vdc sources while plugged in to 115Vac ldquoIts a UPSrdquo
SPECIFICATIONS OF COMPONENTS USED
PLC S7-200
INPUT POWER 230V AC 50 Hz
INPUTS 24 DC INPUTS
OUTPUTS 16 DC OUTPUTS
PROGRAM MEMORY 24
DATA MEMORY 10KB
EXPANSION MODULES 7
COMMUNICATION PORTS 2 RS 485
DIGITAL IO IMAGE SIZE 256(128 in 128 out)
EXECUTION SPEED 022microsecondsinstruction
SENSORS
SENSING RANGE 3mm
HOUSING MATERIAL Brass Nickel Plated
OPERATING VOLTAGE 10-30V
OPERATING CURRENT lt200mA
CONNECTION TYPE Cable
LEDS
DIAMETER 5mm
MAXIMUM VOLTAGE 1V
MAXIMUM CURRENT 10mA
INTENSITY
BUZZERS
OPERATING VOLTAGE30Vp-p
RATED FREQUENCY2000Hz 500Hz
OPERATING TEMP RANGE -20 to 60 degree
SOUND OUTPUT70 dB min10 cm
MOTOR
TOTAL LENGTH 46mm MOTOR DIAMETER 36mm MOTOR LENGTH 25mm DC SUPPLY 4 to 12V RPM 100 BRUSH TYPE Precious metal GEAR HEAD DIAMETER 37mm GEAR HEAD LENGTH 21mm OUTPUT SHAFT Centered SHAFT DIAMETER 4mm and 6mm
SHAFT LENGTH 22mm
- Block diagram of plc
- Applications
-
- Function
- Testing an LED
- Sizes Shapes and Viewing angles of LEDs
- Calculating an LED resistor value
-
- Working out the LED resistor formula using Ohms law
-
proximity sensor targets demand different sensors For example a capacitive or photoelectric sensor might be suitable for a plastic target an inductive proximity sensor requires a metal target
The maximum distance that this sensor can detect is defined nominal range Some sensors have adjustments of the nominal range or means to report a graduated detection distance
Proximity sensors can have a high reliability and long functional life because of the absence of mechanical parts and lack of physical contact between sensor and the sensed object
IEC 60947-5-2 defines the technical details of proximity sensors
A proximity sensor adjusted to a very short range is often used as a touch switch
Applications
Car bumpers that sense distance to nearby cars for parking
Ground proximity warning system for aviation safety Vibration Position measurements of rotating shafts in
machinery Sheet break sensing in paper machine Anti-aircraft artillery
LEDS
Example Circuit symbol
FunctionLEDs emit light when an electric current passes through them
Testing an LED
Never connect an LED directly to a battery or power supply
LEDs must have a resistor in series to limit the current to a safe value for quick testing purposes a 1k resistor is suitable for most LEDs if your supply voltage is 12V or less Remember to connect the LED the correct way round
Sizes Shapes and Viewing angles of LEDs
LEDs are available in a wide variety of sizes and shapes The standard LED has a round cross-section of 5mm diameter and this is probably the best type for general use but 3mm round LEDs are also popular
Round cross-section LEDs are frequently used and they are very easy to install on boxes by drilling a hole of the LED diameter adding a spot of glue will help to hold the LED if necessary LED clips are also available to secure LEDs in holes Other cross-section shapes include square rectangular and triangular
As well as a variety of colours sizes and shapes LEDs also vary in their viewing angle This tells you how much the beam of light spreads out Standard LEDs have a viewing angle of 60deg but others have a narrow beam of 30deg or less
Calculating an LED resistor value
An LED must have a resistor connected in series to limit the current through the LED otherwise it will burn out almost instantly
The resistor value R is given by
R = (VS - VL) I
VS = supply voltage VL = LED voltage (usually 2V but 4V for blue and white LEDs) I = LED current (eg 20mA) this must be less than the maximum permitted
If the calculated value is not available choose the nearest standard resistor value which is greater so that the current will be a little less than you chose In fact you may wish to choose a greater resistor value to reduce the current (to increase battery life for example) but this will make the LED less bright
Working out the LED resistor formula using Ohms law
Ohms law says that the resistance of the resistor R = VI where V = voltage across the resistor (= VS - VL in this case) I = the current through the resistor
So R = (VS - VL) I
BUZZERS
A buzzer or beeper (BUZZERS) is a signalling device usually electronic typically used in automobiles household appliances such as a microwave oven or game shows It most commonly consists of a number of switches or sensors connected to a control unit that determines if and which button was pushed or a preset time has lapsed and usually illuminates a light on the appropriate button or control panel and sounds a warning in the form of a continuous or intermittent buzzing
or beeping sound Initially this device was based on an electromechanical system which was identical to an electric bell without the metal gong (which makes the ringing noise) Often these units were anchored to a wall or ceiling and used the ceiling or wall as a sounding board Another implementation with some AC-connected devices was to implement a circuit to make the AC current into a noise loud enough to drive a loudspeaker and hook this circuit up to a cheap 8-ohm speaker Nowadays it is more popular to use a ceramic-based piezoelectric sounder which makes a high-pitched tone Usually these were hooked up to driver circuits which varied the pitch of the sound or pulsed the sound on and off
The word buzzer comes from the rasping noise that buzzers made when they were electromechanical devices operated from stepped-down AC line voltage at 50 or 60 cycles Other sounds commonly used to indicate that a button has been pressed are a ring or a beep
MOTORS
An electric motor is a device using electrical energy to produce mechanical energy nearly always by the interaction of magnetic fields and current-carrying conductors The reverse process that of using mechanical energy to produce electrical energy is accomplished by a generator or dynamo Traction motors used on vehicles often perform both tasks
Electric motors are found in myriad uses such as industrial fans blowers and pumps machine tools household appliances power tools and computer disk drives among
many other applications Electric motors may be operated by direct current from a battery in a portable device or motor vehicle or from alternating current from a central electrical distribution grid The smallest motors may be found in electric wristwatches Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses The very largest electric motors are used for propulsion of large ships and for such purposes as pipeline compressors with ratings in the thousands of kilowatts Electric motors may be classified by the source of electric power by their internal construction and by application
The physical principle of production of mechanical force by the interaction of an electric current and a magnetic field was known as early as 1821 Electric motors of increasing efficiency were constructed throughout the 19th century but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks
CONNECTORS
A DC connector is an electrical connector for
supplying direct current (DC) power DC connectors
are poorly standardized compared to domestic AC
power plugs and sockets DC plug is a common name
used for one common type of cylindrical two-conductor
plug available in a range of sizes and used to power
small pieces of electronic equipment It is also used to
describe some older multi-pin plugs
Several competing standards exist for DC plugs and in some cases incompatible plugs
will fit together to avoid damaging equipment these conditions must be true
Voltage must match
Polarity is correct
Current ratings are sufficient
Power supply filtering and stability is adequate
for the equipment being powered
Non-matching connectors are forced together
12V DC BATTERY
Features
Less than a 12 volt self discharge per 6 months 4 ea 12Vdc outputs 20 AmpHours Built-charger Digital Voltmeter
Description
This unit supplies a full 12Vdc at 20 AmpHours Designed for the officer that needs a power source that can be charged from 115Ac source or on the way to a incident from the car
The battery source has a very low self discharge rate which makes it perfect for law enforcement use The battery can set on the shelf for more than 6 months without recharging
Everyone knows when you grab a battery operated device the internal battery always requires several hours of charging before using The new voltage indicator reads out voltage to one hundredth of a volt for accurate operation The four outputs are 21mm plug Quick terminals and Cigarette lighter jack amp PT02 (Mil Spec) This model also allows powering
12Vdc sources while plugged in to 115Vac ldquoIts a UPSrdquo
SPECIFICATIONS OF COMPONENTS USED
PLC S7-200
INPUT POWER 230V AC 50 Hz
INPUTS 24 DC INPUTS
OUTPUTS 16 DC OUTPUTS
PROGRAM MEMORY 24
DATA MEMORY 10KB
EXPANSION MODULES 7
COMMUNICATION PORTS 2 RS 485
DIGITAL IO IMAGE SIZE 256(128 in 128 out)
EXECUTION SPEED 022microsecondsinstruction
SENSORS
SENSING RANGE 3mm
HOUSING MATERIAL Brass Nickel Plated
OPERATING VOLTAGE 10-30V
OPERATING CURRENT lt200mA
CONNECTION TYPE Cable
LEDS
DIAMETER 5mm
MAXIMUM VOLTAGE 1V
MAXIMUM CURRENT 10mA
INTENSITY
BUZZERS
OPERATING VOLTAGE30Vp-p
RATED FREQUENCY2000Hz 500Hz
OPERATING TEMP RANGE -20 to 60 degree
SOUND OUTPUT70 dB min10 cm
MOTOR
TOTAL LENGTH 46mm MOTOR DIAMETER 36mm MOTOR LENGTH 25mm DC SUPPLY 4 to 12V RPM 100 BRUSH TYPE Precious metal GEAR HEAD DIAMETER 37mm GEAR HEAD LENGTH 21mm OUTPUT SHAFT Centered SHAFT DIAMETER 4mm and 6mm
SHAFT LENGTH 22mm
- Block diagram of plc
- Applications
-
- Function
- Testing an LED
- Sizes Shapes and Viewing angles of LEDs
- Calculating an LED resistor value
-
- Working out the LED resistor formula using Ohms law
-
FunctionLEDs emit light when an electric current passes through them
Testing an LED
Never connect an LED directly to a battery or power supply
LEDs must have a resistor in series to limit the current to a safe value for quick testing purposes a 1k resistor is suitable for most LEDs if your supply voltage is 12V or less Remember to connect the LED the correct way round
Sizes Shapes and Viewing angles of LEDs
LEDs are available in a wide variety of sizes and shapes The standard LED has a round cross-section of 5mm diameter and this is probably the best type for general use but 3mm round LEDs are also popular
Round cross-section LEDs are frequently used and they are very easy to install on boxes by drilling a hole of the LED diameter adding a spot of glue will help to hold the LED if necessary LED clips are also available to secure LEDs in holes Other cross-section shapes include square rectangular and triangular
As well as a variety of colours sizes and shapes LEDs also vary in their viewing angle This tells you how much the beam of light spreads out Standard LEDs have a viewing angle of 60deg but others have a narrow beam of 30deg or less
Calculating an LED resistor value
An LED must have a resistor connected in series to limit the current through the LED otherwise it will burn out almost instantly
The resistor value R is given by
R = (VS - VL) I
VS = supply voltage VL = LED voltage (usually 2V but 4V for blue and white LEDs) I = LED current (eg 20mA) this must be less than the maximum permitted
If the calculated value is not available choose the nearest standard resistor value which is greater so that the current will be a little less than you chose In fact you may wish to choose a greater resistor value to reduce the current (to increase battery life for example) but this will make the LED less bright
Working out the LED resistor formula using Ohms law
Ohms law says that the resistance of the resistor R = VI where V = voltage across the resistor (= VS - VL in this case) I = the current through the resistor
So R = (VS - VL) I
BUZZERS
A buzzer or beeper (BUZZERS) is a signalling device usually electronic typically used in automobiles household appliances such as a microwave oven or game shows It most commonly consists of a number of switches or sensors connected to a control unit that determines if and which button was pushed or a preset time has lapsed and usually illuminates a light on the appropriate button or control panel and sounds a warning in the form of a continuous or intermittent buzzing
or beeping sound Initially this device was based on an electromechanical system which was identical to an electric bell without the metal gong (which makes the ringing noise) Often these units were anchored to a wall or ceiling and used the ceiling or wall as a sounding board Another implementation with some AC-connected devices was to implement a circuit to make the AC current into a noise loud enough to drive a loudspeaker and hook this circuit up to a cheap 8-ohm speaker Nowadays it is more popular to use a ceramic-based piezoelectric sounder which makes a high-pitched tone Usually these were hooked up to driver circuits which varied the pitch of the sound or pulsed the sound on and off
The word buzzer comes from the rasping noise that buzzers made when they were electromechanical devices operated from stepped-down AC line voltage at 50 or 60 cycles Other sounds commonly used to indicate that a button has been pressed are a ring or a beep
MOTORS
An electric motor is a device using electrical energy to produce mechanical energy nearly always by the interaction of magnetic fields and current-carrying conductors The reverse process that of using mechanical energy to produce electrical energy is accomplished by a generator or dynamo Traction motors used on vehicles often perform both tasks
Electric motors are found in myriad uses such as industrial fans blowers and pumps machine tools household appliances power tools and computer disk drives among
many other applications Electric motors may be operated by direct current from a battery in a portable device or motor vehicle or from alternating current from a central electrical distribution grid The smallest motors may be found in electric wristwatches Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses The very largest electric motors are used for propulsion of large ships and for such purposes as pipeline compressors with ratings in the thousands of kilowatts Electric motors may be classified by the source of electric power by their internal construction and by application
The physical principle of production of mechanical force by the interaction of an electric current and a magnetic field was known as early as 1821 Electric motors of increasing efficiency were constructed throughout the 19th century but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks
CONNECTORS
A DC connector is an electrical connector for
supplying direct current (DC) power DC connectors
are poorly standardized compared to domestic AC
power plugs and sockets DC plug is a common name
used for one common type of cylindrical two-conductor
plug available in a range of sizes and used to power
small pieces of electronic equipment It is also used to
describe some older multi-pin plugs
Several competing standards exist for DC plugs and in some cases incompatible plugs
will fit together to avoid damaging equipment these conditions must be true
Voltage must match
Polarity is correct
Current ratings are sufficient
Power supply filtering and stability is adequate
for the equipment being powered
Non-matching connectors are forced together
12V DC BATTERY
Features
Less than a 12 volt self discharge per 6 months 4 ea 12Vdc outputs 20 AmpHours Built-charger Digital Voltmeter
Description
This unit supplies a full 12Vdc at 20 AmpHours Designed for the officer that needs a power source that can be charged from 115Ac source or on the way to a incident from the car
The battery source has a very low self discharge rate which makes it perfect for law enforcement use The battery can set on the shelf for more than 6 months without recharging
Everyone knows when you grab a battery operated device the internal battery always requires several hours of charging before using The new voltage indicator reads out voltage to one hundredth of a volt for accurate operation The four outputs are 21mm plug Quick terminals and Cigarette lighter jack amp PT02 (Mil Spec) This model also allows powering
12Vdc sources while plugged in to 115Vac ldquoIts a UPSrdquo
SPECIFICATIONS OF COMPONENTS USED
PLC S7-200
INPUT POWER 230V AC 50 Hz
INPUTS 24 DC INPUTS
OUTPUTS 16 DC OUTPUTS
PROGRAM MEMORY 24
DATA MEMORY 10KB
EXPANSION MODULES 7
COMMUNICATION PORTS 2 RS 485
DIGITAL IO IMAGE SIZE 256(128 in 128 out)
EXECUTION SPEED 022microsecondsinstruction
SENSORS
SENSING RANGE 3mm
HOUSING MATERIAL Brass Nickel Plated
OPERATING VOLTAGE 10-30V
OPERATING CURRENT lt200mA
CONNECTION TYPE Cable
LEDS
DIAMETER 5mm
MAXIMUM VOLTAGE 1V
MAXIMUM CURRENT 10mA
INTENSITY
BUZZERS
OPERATING VOLTAGE30Vp-p
RATED FREQUENCY2000Hz 500Hz
OPERATING TEMP RANGE -20 to 60 degree
SOUND OUTPUT70 dB min10 cm
MOTOR
TOTAL LENGTH 46mm MOTOR DIAMETER 36mm MOTOR LENGTH 25mm DC SUPPLY 4 to 12V RPM 100 BRUSH TYPE Precious metal GEAR HEAD DIAMETER 37mm GEAR HEAD LENGTH 21mm OUTPUT SHAFT Centered SHAFT DIAMETER 4mm and 6mm
SHAFT LENGTH 22mm
- Block diagram of plc
- Applications
-
- Function
- Testing an LED
- Sizes Shapes and Viewing angles of LEDs
- Calculating an LED resistor value
-
- Working out the LED resistor formula using Ohms law
-
The resistor value R is given by
R = (VS - VL) I
VS = supply voltage VL = LED voltage (usually 2V but 4V for blue and white LEDs) I = LED current (eg 20mA) this must be less than the maximum permitted
If the calculated value is not available choose the nearest standard resistor value which is greater so that the current will be a little less than you chose In fact you may wish to choose a greater resistor value to reduce the current (to increase battery life for example) but this will make the LED less bright
Working out the LED resistor formula using Ohms law
Ohms law says that the resistance of the resistor R = VI where V = voltage across the resistor (= VS - VL in this case) I = the current through the resistor
So R = (VS - VL) I
BUZZERS
A buzzer or beeper (BUZZERS) is a signalling device usually electronic typically used in automobiles household appliances such as a microwave oven or game shows It most commonly consists of a number of switches or sensors connected to a control unit that determines if and which button was pushed or a preset time has lapsed and usually illuminates a light on the appropriate button or control panel and sounds a warning in the form of a continuous or intermittent buzzing
or beeping sound Initially this device was based on an electromechanical system which was identical to an electric bell without the metal gong (which makes the ringing noise) Often these units were anchored to a wall or ceiling and used the ceiling or wall as a sounding board Another implementation with some AC-connected devices was to implement a circuit to make the AC current into a noise loud enough to drive a loudspeaker and hook this circuit up to a cheap 8-ohm speaker Nowadays it is more popular to use a ceramic-based piezoelectric sounder which makes a high-pitched tone Usually these were hooked up to driver circuits which varied the pitch of the sound or pulsed the sound on and off
The word buzzer comes from the rasping noise that buzzers made when they were electromechanical devices operated from stepped-down AC line voltage at 50 or 60 cycles Other sounds commonly used to indicate that a button has been pressed are a ring or a beep
MOTORS
An electric motor is a device using electrical energy to produce mechanical energy nearly always by the interaction of magnetic fields and current-carrying conductors The reverse process that of using mechanical energy to produce electrical energy is accomplished by a generator or dynamo Traction motors used on vehicles often perform both tasks
Electric motors are found in myriad uses such as industrial fans blowers and pumps machine tools household appliances power tools and computer disk drives among
many other applications Electric motors may be operated by direct current from a battery in a portable device or motor vehicle or from alternating current from a central electrical distribution grid The smallest motors may be found in electric wristwatches Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses The very largest electric motors are used for propulsion of large ships and for such purposes as pipeline compressors with ratings in the thousands of kilowatts Electric motors may be classified by the source of electric power by their internal construction and by application
The physical principle of production of mechanical force by the interaction of an electric current and a magnetic field was known as early as 1821 Electric motors of increasing efficiency were constructed throughout the 19th century but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks
CONNECTORS
A DC connector is an electrical connector for
supplying direct current (DC) power DC connectors
are poorly standardized compared to domestic AC
power plugs and sockets DC plug is a common name
used for one common type of cylindrical two-conductor
plug available in a range of sizes and used to power
small pieces of electronic equipment It is also used to
describe some older multi-pin plugs
Several competing standards exist for DC plugs and in some cases incompatible plugs
will fit together to avoid damaging equipment these conditions must be true
Voltage must match
Polarity is correct
Current ratings are sufficient
Power supply filtering and stability is adequate
for the equipment being powered
Non-matching connectors are forced together
12V DC BATTERY
Features
Less than a 12 volt self discharge per 6 months 4 ea 12Vdc outputs 20 AmpHours Built-charger Digital Voltmeter
Description
This unit supplies a full 12Vdc at 20 AmpHours Designed for the officer that needs a power source that can be charged from 115Ac source or on the way to a incident from the car
The battery source has a very low self discharge rate which makes it perfect for law enforcement use The battery can set on the shelf for more than 6 months without recharging
Everyone knows when you grab a battery operated device the internal battery always requires several hours of charging before using The new voltage indicator reads out voltage to one hundredth of a volt for accurate operation The four outputs are 21mm plug Quick terminals and Cigarette lighter jack amp PT02 (Mil Spec) This model also allows powering
12Vdc sources while plugged in to 115Vac ldquoIts a UPSrdquo
SPECIFICATIONS OF COMPONENTS USED
PLC S7-200
INPUT POWER 230V AC 50 Hz
INPUTS 24 DC INPUTS
OUTPUTS 16 DC OUTPUTS
PROGRAM MEMORY 24
DATA MEMORY 10KB
EXPANSION MODULES 7
COMMUNICATION PORTS 2 RS 485
DIGITAL IO IMAGE SIZE 256(128 in 128 out)
EXECUTION SPEED 022microsecondsinstruction
SENSORS
SENSING RANGE 3mm
HOUSING MATERIAL Brass Nickel Plated
OPERATING VOLTAGE 10-30V
OPERATING CURRENT lt200mA
CONNECTION TYPE Cable
LEDS
DIAMETER 5mm
MAXIMUM VOLTAGE 1V
MAXIMUM CURRENT 10mA
INTENSITY
BUZZERS
OPERATING VOLTAGE30Vp-p
RATED FREQUENCY2000Hz 500Hz
OPERATING TEMP RANGE -20 to 60 degree
SOUND OUTPUT70 dB min10 cm
MOTOR
TOTAL LENGTH 46mm MOTOR DIAMETER 36mm MOTOR LENGTH 25mm DC SUPPLY 4 to 12V RPM 100 BRUSH TYPE Precious metal GEAR HEAD DIAMETER 37mm GEAR HEAD LENGTH 21mm OUTPUT SHAFT Centered SHAFT DIAMETER 4mm and 6mm
SHAFT LENGTH 22mm
- Block diagram of plc
- Applications
-
- Function
- Testing an LED
- Sizes Shapes and Viewing angles of LEDs
- Calculating an LED resistor value
-
- Working out the LED resistor formula using Ohms law
-
or beeping sound Initially this device was based on an electromechanical system which was identical to an electric bell without the metal gong (which makes the ringing noise) Often these units were anchored to a wall or ceiling and used the ceiling or wall as a sounding board Another implementation with some AC-connected devices was to implement a circuit to make the AC current into a noise loud enough to drive a loudspeaker and hook this circuit up to a cheap 8-ohm speaker Nowadays it is more popular to use a ceramic-based piezoelectric sounder which makes a high-pitched tone Usually these were hooked up to driver circuits which varied the pitch of the sound or pulsed the sound on and off
The word buzzer comes from the rasping noise that buzzers made when they were electromechanical devices operated from stepped-down AC line voltage at 50 or 60 cycles Other sounds commonly used to indicate that a button has been pressed are a ring or a beep
MOTORS
An electric motor is a device using electrical energy to produce mechanical energy nearly always by the interaction of magnetic fields and current-carrying conductors The reverse process that of using mechanical energy to produce electrical energy is accomplished by a generator or dynamo Traction motors used on vehicles often perform both tasks
Electric motors are found in myriad uses such as industrial fans blowers and pumps machine tools household appliances power tools and computer disk drives among
many other applications Electric motors may be operated by direct current from a battery in a portable device or motor vehicle or from alternating current from a central electrical distribution grid The smallest motors may be found in electric wristwatches Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses The very largest electric motors are used for propulsion of large ships and for such purposes as pipeline compressors with ratings in the thousands of kilowatts Electric motors may be classified by the source of electric power by their internal construction and by application
The physical principle of production of mechanical force by the interaction of an electric current and a magnetic field was known as early as 1821 Electric motors of increasing efficiency were constructed throughout the 19th century but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks
CONNECTORS
A DC connector is an electrical connector for
supplying direct current (DC) power DC connectors
are poorly standardized compared to domestic AC
power plugs and sockets DC plug is a common name
used for one common type of cylindrical two-conductor
plug available in a range of sizes and used to power
small pieces of electronic equipment It is also used to
describe some older multi-pin plugs
Several competing standards exist for DC plugs and in some cases incompatible plugs
will fit together to avoid damaging equipment these conditions must be true
Voltage must match
Polarity is correct
Current ratings are sufficient
Power supply filtering and stability is adequate
for the equipment being powered
Non-matching connectors are forced together
12V DC BATTERY
Features
Less than a 12 volt self discharge per 6 months 4 ea 12Vdc outputs 20 AmpHours Built-charger Digital Voltmeter
Description
This unit supplies a full 12Vdc at 20 AmpHours Designed for the officer that needs a power source that can be charged from 115Ac source or on the way to a incident from the car
The battery source has a very low self discharge rate which makes it perfect for law enforcement use The battery can set on the shelf for more than 6 months without recharging
Everyone knows when you grab a battery operated device the internal battery always requires several hours of charging before using The new voltage indicator reads out voltage to one hundredth of a volt for accurate operation The four outputs are 21mm plug Quick terminals and Cigarette lighter jack amp PT02 (Mil Spec) This model also allows powering
12Vdc sources while plugged in to 115Vac ldquoIts a UPSrdquo
SPECIFICATIONS OF COMPONENTS USED
PLC S7-200
INPUT POWER 230V AC 50 Hz
INPUTS 24 DC INPUTS
OUTPUTS 16 DC OUTPUTS
PROGRAM MEMORY 24
DATA MEMORY 10KB
EXPANSION MODULES 7
COMMUNICATION PORTS 2 RS 485
DIGITAL IO IMAGE SIZE 256(128 in 128 out)
EXECUTION SPEED 022microsecondsinstruction
SENSORS
SENSING RANGE 3mm
HOUSING MATERIAL Brass Nickel Plated
OPERATING VOLTAGE 10-30V
OPERATING CURRENT lt200mA
CONNECTION TYPE Cable
LEDS
DIAMETER 5mm
MAXIMUM VOLTAGE 1V
MAXIMUM CURRENT 10mA
INTENSITY
BUZZERS
OPERATING VOLTAGE30Vp-p
RATED FREQUENCY2000Hz 500Hz
OPERATING TEMP RANGE -20 to 60 degree
SOUND OUTPUT70 dB min10 cm
MOTOR
TOTAL LENGTH 46mm MOTOR DIAMETER 36mm MOTOR LENGTH 25mm DC SUPPLY 4 to 12V RPM 100 BRUSH TYPE Precious metal GEAR HEAD DIAMETER 37mm GEAR HEAD LENGTH 21mm OUTPUT SHAFT Centered SHAFT DIAMETER 4mm and 6mm
SHAFT LENGTH 22mm
- Block diagram of plc
- Applications
-
- Function
- Testing an LED
- Sizes Shapes and Viewing angles of LEDs
- Calculating an LED resistor value
-
- Working out the LED resistor formula using Ohms law
-
many other applications Electric motors may be operated by direct current from a battery in a portable device or motor vehicle or from alternating current from a central electrical distribution grid The smallest motors may be found in electric wristwatches Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses The very largest electric motors are used for propulsion of large ships and for such purposes as pipeline compressors with ratings in the thousands of kilowatts Electric motors may be classified by the source of electric power by their internal construction and by application
The physical principle of production of mechanical force by the interaction of an electric current and a magnetic field was known as early as 1821 Electric motors of increasing efficiency were constructed throughout the 19th century but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks
CONNECTORS
A DC connector is an electrical connector for
supplying direct current (DC) power DC connectors
are poorly standardized compared to domestic AC
power plugs and sockets DC plug is a common name
used for one common type of cylindrical two-conductor
plug available in a range of sizes and used to power
small pieces of electronic equipment It is also used to
describe some older multi-pin plugs
Several competing standards exist for DC plugs and in some cases incompatible plugs
will fit together to avoid damaging equipment these conditions must be true
Voltage must match
Polarity is correct
Current ratings are sufficient
Power supply filtering and stability is adequate
for the equipment being powered
Non-matching connectors are forced together
12V DC BATTERY
Features
Less than a 12 volt self discharge per 6 months 4 ea 12Vdc outputs 20 AmpHours Built-charger Digital Voltmeter
Description
This unit supplies a full 12Vdc at 20 AmpHours Designed for the officer that needs a power source that can be charged from 115Ac source or on the way to a incident from the car
The battery source has a very low self discharge rate which makes it perfect for law enforcement use The battery can set on the shelf for more than 6 months without recharging
Everyone knows when you grab a battery operated device the internal battery always requires several hours of charging before using The new voltage indicator reads out voltage to one hundredth of a volt for accurate operation The four outputs are 21mm plug Quick terminals and Cigarette lighter jack amp PT02 (Mil Spec) This model also allows powering
12Vdc sources while plugged in to 115Vac ldquoIts a UPSrdquo
SPECIFICATIONS OF COMPONENTS USED
PLC S7-200
INPUT POWER 230V AC 50 Hz
INPUTS 24 DC INPUTS
OUTPUTS 16 DC OUTPUTS
PROGRAM MEMORY 24
DATA MEMORY 10KB
EXPANSION MODULES 7
COMMUNICATION PORTS 2 RS 485
DIGITAL IO IMAGE SIZE 256(128 in 128 out)
EXECUTION SPEED 022microsecondsinstruction
SENSORS
SENSING RANGE 3mm
HOUSING MATERIAL Brass Nickel Plated
OPERATING VOLTAGE 10-30V
OPERATING CURRENT lt200mA
CONNECTION TYPE Cable
LEDS
DIAMETER 5mm
MAXIMUM VOLTAGE 1V
MAXIMUM CURRENT 10mA
INTENSITY
BUZZERS
OPERATING VOLTAGE30Vp-p
RATED FREQUENCY2000Hz 500Hz
OPERATING TEMP RANGE -20 to 60 degree
SOUND OUTPUT70 dB min10 cm
MOTOR
TOTAL LENGTH 46mm MOTOR DIAMETER 36mm MOTOR LENGTH 25mm DC SUPPLY 4 to 12V RPM 100 BRUSH TYPE Precious metal GEAR HEAD DIAMETER 37mm GEAR HEAD LENGTH 21mm OUTPUT SHAFT Centered SHAFT DIAMETER 4mm and 6mm
SHAFT LENGTH 22mm
- Block diagram of plc
- Applications
-
- Function
- Testing an LED
- Sizes Shapes and Viewing angles of LEDs
- Calculating an LED resistor value
-
- Working out the LED resistor formula using Ohms law
-
Several competing standards exist for DC plugs and in some cases incompatible plugs
will fit together to avoid damaging equipment these conditions must be true
Voltage must match
Polarity is correct
Current ratings are sufficient
Power supply filtering and stability is adequate
for the equipment being powered
Non-matching connectors are forced together
12V DC BATTERY
Features
Less than a 12 volt self discharge per 6 months 4 ea 12Vdc outputs 20 AmpHours Built-charger Digital Voltmeter
Description
This unit supplies a full 12Vdc at 20 AmpHours Designed for the officer that needs a power source that can be charged from 115Ac source or on the way to a incident from the car
The battery source has a very low self discharge rate which makes it perfect for law enforcement use The battery can set on the shelf for more than 6 months without recharging
Everyone knows when you grab a battery operated device the internal battery always requires several hours of charging before using The new voltage indicator reads out voltage to one hundredth of a volt for accurate operation The four outputs are 21mm plug Quick terminals and Cigarette lighter jack amp PT02 (Mil Spec) This model also allows powering
12Vdc sources while plugged in to 115Vac ldquoIts a UPSrdquo
SPECIFICATIONS OF COMPONENTS USED
PLC S7-200
INPUT POWER 230V AC 50 Hz
INPUTS 24 DC INPUTS
OUTPUTS 16 DC OUTPUTS
PROGRAM MEMORY 24
DATA MEMORY 10KB
EXPANSION MODULES 7
COMMUNICATION PORTS 2 RS 485
DIGITAL IO IMAGE SIZE 256(128 in 128 out)
EXECUTION SPEED 022microsecondsinstruction
SENSORS
SENSING RANGE 3mm
HOUSING MATERIAL Brass Nickel Plated
OPERATING VOLTAGE 10-30V
OPERATING CURRENT lt200mA
CONNECTION TYPE Cable
LEDS
DIAMETER 5mm
MAXIMUM VOLTAGE 1V
MAXIMUM CURRENT 10mA
INTENSITY
BUZZERS
OPERATING VOLTAGE30Vp-p
RATED FREQUENCY2000Hz 500Hz
OPERATING TEMP RANGE -20 to 60 degree
SOUND OUTPUT70 dB min10 cm
MOTOR
TOTAL LENGTH 46mm MOTOR DIAMETER 36mm MOTOR LENGTH 25mm DC SUPPLY 4 to 12V RPM 100 BRUSH TYPE Precious metal GEAR HEAD DIAMETER 37mm GEAR HEAD LENGTH 21mm OUTPUT SHAFT Centered SHAFT DIAMETER 4mm and 6mm
SHAFT LENGTH 22mm
- Block diagram of plc
- Applications
-
- Function
- Testing an LED
- Sizes Shapes and Viewing angles of LEDs
- Calculating an LED resistor value
-
- Working out the LED resistor formula using Ohms law
-
This unit supplies a full 12Vdc at 20 AmpHours Designed for the officer that needs a power source that can be charged from 115Ac source or on the way to a incident from the car
The battery source has a very low self discharge rate which makes it perfect for law enforcement use The battery can set on the shelf for more than 6 months without recharging
Everyone knows when you grab a battery operated device the internal battery always requires several hours of charging before using The new voltage indicator reads out voltage to one hundredth of a volt for accurate operation The four outputs are 21mm plug Quick terminals and Cigarette lighter jack amp PT02 (Mil Spec) This model also allows powering
12Vdc sources while plugged in to 115Vac ldquoIts a UPSrdquo
SPECIFICATIONS OF COMPONENTS USED
PLC S7-200
INPUT POWER 230V AC 50 Hz
INPUTS 24 DC INPUTS
OUTPUTS 16 DC OUTPUTS
PROGRAM MEMORY 24
DATA MEMORY 10KB
EXPANSION MODULES 7
COMMUNICATION PORTS 2 RS 485
DIGITAL IO IMAGE SIZE 256(128 in 128 out)
EXECUTION SPEED 022microsecondsinstruction
SENSORS
SENSING RANGE 3mm
HOUSING MATERIAL Brass Nickel Plated
OPERATING VOLTAGE 10-30V
OPERATING CURRENT lt200mA
CONNECTION TYPE Cable
LEDS
DIAMETER 5mm
MAXIMUM VOLTAGE 1V
MAXIMUM CURRENT 10mA
INTENSITY
BUZZERS
OPERATING VOLTAGE30Vp-p
RATED FREQUENCY2000Hz 500Hz
OPERATING TEMP RANGE -20 to 60 degree
SOUND OUTPUT70 dB min10 cm
MOTOR
TOTAL LENGTH 46mm MOTOR DIAMETER 36mm MOTOR LENGTH 25mm DC SUPPLY 4 to 12V RPM 100 BRUSH TYPE Precious metal GEAR HEAD DIAMETER 37mm GEAR HEAD LENGTH 21mm OUTPUT SHAFT Centered SHAFT DIAMETER 4mm and 6mm
SHAFT LENGTH 22mm
- Block diagram of plc
- Applications
-
- Function
- Testing an LED
- Sizes Shapes and Viewing angles of LEDs
- Calculating an LED resistor value
-
- Working out the LED resistor formula using Ohms law
-
HOUSING MATERIAL Brass Nickel Plated
OPERATING VOLTAGE 10-30V
OPERATING CURRENT lt200mA
CONNECTION TYPE Cable
LEDS
DIAMETER 5mm
MAXIMUM VOLTAGE 1V
MAXIMUM CURRENT 10mA
INTENSITY
BUZZERS
OPERATING VOLTAGE30Vp-p
RATED FREQUENCY2000Hz 500Hz
OPERATING TEMP RANGE -20 to 60 degree
SOUND OUTPUT70 dB min10 cm
MOTOR
TOTAL LENGTH 46mm MOTOR DIAMETER 36mm MOTOR LENGTH 25mm DC SUPPLY 4 to 12V RPM 100 BRUSH TYPE Precious metal GEAR HEAD DIAMETER 37mm GEAR HEAD LENGTH 21mm OUTPUT SHAFT Centered SHAFT DIAMETER 4mm and 6mm
SHAFT LENGTH 22mm
- Block diagram of plc
- Applications
-
- Function
- Testing an LED
- Sizes Shapes and Viewing angles of LEDs
- Calculating an LED resistor value
-
- Working out the LED resistor formula using Ohms law
-
- Block diagram of plc
- Applications
-
- Function
- Testing an LED
- Sizes Shapes and Viewing angles of LEDs
- Calculating an LED resistor value
-
- Working out the LED resistor formula using Ohms law
-
