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FAKULTAS TEKNOLOGI INDUSTRI
ITSSURABAYA
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MATERI :
Konsep dasar Programmable Logic Control
Sequential Process
Safety Instrument System (SIS)
SCADA
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Konsep dasar PLC
Invented in 1968
as a substitute for hardwired relay panels.
"A digitally operating electronic apparatus which uses a programmable
memory for the internal storage of instructions by implementing specific
functions such as logic sequencing, timing, counting, and arithmetic to
control, through digital or analog input/output modules, various types ofmachines or processes. The digital computer which is used to perform the
functions of a programmable controller is considered to be within this
scope. Excluded are drum and other similar mechanical sequencing
controllers."
National Electrical Manufacturing Association (NEMA)23/05/2014 3Instrument 2
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CPU
System
User LadderDiagram
Workingmemoryregisters
Input
Flag
Output
InputModule
OutputModule
Komponen PLC
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The main module measures
19 x 20 x 14.5.
have up to 10,000 I/O points
supports all functions
expansion slots toaccommodate PC and other
communication devices.
A large size PLC
Allan-Bradley PLC-3
A small size PLC
Measures 4.72x 3.15 x 1.57.
32 I/O points
Standard RS 232 serialcommunication port
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DPSTSPDT
N o n -lo c k in g Lo c k in g
No r m a lly O p e n No r m a lly C lo
s e d
Mu ltip le Th r o w
P 1
P 2
Mu ltip le P o l
e
Br e a k - b e fo r e - m a k
e Ma ke -b e fo re -b r
e a k
SWITCHES
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Throw - number of states
Pole - number of connecting moving parts (number of individual
circuits).
SPDT
DPST
A serial switch box (A-B box) hastwo 25 pin serial ports to switch from.
Input
Output
A B
Knob
How is this switch classified?
TERMS
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Selector switches
Pushbutton switches
Photoelectricswitches
Limit Switches
Proximity switches
Level switches Thumbwheel
switches
Slide switches
RATING:
24 Volts AC/DC48 Volts AC/DC120 Volts AC/DC
230 Volts AC/DCTTL level(Transistor-to-transistor5V)
Isolated Input
TYPES OF SWITCHES
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A switch whose operation is activated by an electromagnet is called a "relay"
contact
coil
input
Relay coil
R1
R1Output contact
RELAYS
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Digital counters output in the form of a relay contact when a preassigned count value is
reached.
Register
Accumulator
contact
input
reset
outpu
Input
Reset
Output
Count 0 1 2 3 4 5 0 1
5
COUNTER
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A timer consists of an internal clock, a count value register, and an accumulator. It is
used for or some timing purpose.
Clock
Accumulator
contact
reset
outpu
Register
Contact
Time 5 seconds.
Clock
Reset
Output
Count 1 2 3 40 5
TIMER
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L1
LS1 PB1 LS2 R1
R1
R1TIMER
R2
PR=5
For a process control, it is desired to have the process start (by turning on a motor)five seconds after a part touched a limit switch. The process is terminatedautomatically when the finished part touches a second limit switch. An emergencyswitch will stop the process any time when it is pushed.
LS1
PB1LS2
R1
TIMER
5Motor
R2
AN EXAMPLE OF RELAY LOGIC
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Programmable controllers replace most of the relay panel wiring by software programming.
Processor I/O
Modules
MemoryPower
Supply
Program
Loader
Printer
CassetteLoader
EPROM
Loader
Switches
Machines
Peripherals Exter nal Device
PC
A typical PLC
PLC ARCHITECTURE
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1. Processor Microprocessor based, may allow arithmetic
operations, logic operators, block memory moves,computer interface, local area network, functions, etc.
2. Memory Measured in words.
ROM (Read Only Memory),
RAM (Random Access Memory),PROM (Programmable Read Only Memory),
EEPROM (Electric Erasable Programmable ROM),
EPROM (Erasable Programmable Read Only Memory),
EAPROM (Electronically Alterable Programmable
Read Only Memory), and
Bubble Memory.
PLC COMPONENTS
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3. I/O Modular plug-in periphery
AC voltage input and output,
DC voltage input and output,
Low level analog input,
High level analog input and output,
Special purpose modules, e.g., high speed timers,
Stepping motor controllers, etc. PID, Motion
4. Power supply AC power
5. Peripheral hand-held programmer (HHP)
CRT programmer
operator console
printer
simulator
EPROM loader
graphics processor
network communication interface
modular PC
PLC COMPONENTS
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AC Voltage I/O DC Voltage I/O
numerical input and output
special-purpose modules, for example,high-speed timers, and stepping motorcontrollers
Discrete I/O
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Analog inputs: Flow sensors Humidity sensors Potentiometers Pressure sensors
Temperature sensors
Analog outputs: Analog meters Analog valves and actuators DC and AC motor drives
Analog I/O
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Thermocouple input
Low level analog signal, filtered, amplified, and digitizedbefore sending to the processor through I/O bus. Fast input
50 to 100 microsecond pulse signal detection. ASCII I/O
Communicates with ASCII devices. Stepper motor output
Provide directly control of a stepper motor. Servo interface
Control DC servo motor for point-to-point control and
axis positioning. PID control
The Proportional Integral Derivative is used for closedloop process control.
Network module
Some special I/O
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n Allen-Bradley hand-held programmer for MicroLogix 1000
A Hand Held Programmer
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A ladder diagram (also called contact symbology) is a means of graphically
representing the logic required in a relay logic system.
A
R1
PB1 PB2
R1
R1
start emergency stop
Rail
Rung
Ladder diagram
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Externalswitches
Stored program
01 02 20
20
2011
01
02
03
11
12
C
PLCInput OutputA
B
PLC WIRING DIAGRAM
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AC DC TTL
Input Connections
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AC DC TTL
Output Connections
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A PLC resolves the logic of a ladder diagram (program) rung by rung, from the top to
the bottom. Usually, all the outputs are updated based on the status of the internalregisters. Then the input states are checked and the corresponding input registers are
updated. Only after the I/Os have been resolved, is the program then executed. This
process is run in a endless cycle. The time it takes to finish one cycle is called the
scan time. In some controllers the idle state is eliminated. In this case, the scan time
varies depends on the program length.
begin
Input
Output
Resolvelogic
Idle
Scan cycle
SCAN
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Ladder Diagram - most common
Structure Text Programming (ST)
Functional Block Programming (FB)
Instruction List (IL)
Sequential Function Chart (SFC)
PLC Programming
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1) Relay,
2) Timer and counter,
3) Program control,
4) Arithmetic,
5) Data manipulation,
6) Data transfer, and
7) Others, such as sequencers.
PLC Ladder Diagram INSTRUCTIONS
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ON : TRUE, contact closure, energize, etc.
OFF: FALSE, contact open , de-energize, etc.
(In the notes we use the symbol "~" to represent negation. AND
and OR are logic operators. )
Do not confuse the internal relay and program with the externalswitch and relay. Internal symbols are used for programming.External devices provide actual interface.
LOGIC STATES
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PB1 R1PB2
R2
R1 = PB1.AND.PB2
R2 = PB2.AND.~PB4
PB3 PB4
PB1 R1
PB2
R1 = PB1 .OR. PB2
AND
OR
AND and OR LOGIC
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R1 = PB1 .OR. (PB2 .AND. PB3)
PB1 R1
PB2 pb3
COMBINED AND & OR
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Coil:
e. Retentive memory Coil -(M)-
f. Set retentive memory Coil -(SM)-
g. Reset retentive memory Coil -(RM)-
h. Positive Transition-sensing Coil -(P)-
h. Negative Transition-sensing Coil -(N)-
(set coil latches the state, reset coil deenergize the set coil. retentive
coil retain the state after power failure.)
Relay (continue)
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Timers:
a. Retentive on delay -(RTO)-
b. Retentive off delay -(RTF)-
c. Reset -(RST)-
Counter:
a. Counter up -(CTU)-
b. Counter down -(CTD)-c. Counter reset -(CTR)-
RTO counting stop countingresume
RTF stop counting stop
True False True
Input
RTO reach PR value, output ONRTF reach PR value, output OFF
PR value in 0.1 second
TIMERS AND COUNTERS
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Sequencers are used with machines or processes involving repeating
operating cycles which can be segmented into steps.
Output
Step A B C Dwell time
1 ON OFF OFF 5 sec.
2 ON ON OFF 10 sec.
3 OFF OFF ON 3 sec.
4 OFF ON OFF 9 sec.
SEQUENCER
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I/O points are numbered, they correspond to the I/O slot on the PLC.
For A-B controller used in our lab
I/O uses 1-32
Internal relays use 033 - 098
Internal timers/counters/sequencers use 901-932
Status 951-982
A-B PLC
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Part
microswitch
Bar code reader
Stopper
Conveyor
MachineRobot
id description state explanation
MSI microswitch 1 part arrive
R1 output to bar code reader 1 scan the part
C1 input from bar code reader 1 right part
R2 output robot 1 loading cycle
R3 output robot 1 unloading cycle
C2 input from robot 1 robot busy
R4 output to stopper 1 stopper up
C3 input from machine 1 machine busy
C4 input from machine 1 task complete
PROGRAMMING EXAMPLE 1
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0102
03
04
05
1112
13
14
15
InputOutput
ProgrammableControllerPLC
MS1
C1
C2
C3
C4
R1R2
R3
R4
01 14 11
02
14 04 03
14
12
1305 03
Rung 1. If part arrives and no part
is stopped, trigger the bar codereader.
Rung 2. If it is a right part, activatethe stopper.
Rung 3. If the stopper is up, themachine is not busy and therobot is not busy, load the partonto the machine.
Rung 4. If the task is completed andthe robot is not busy, unload themachine.
SOLUTION
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