A SEMINAR ON

“ PROGRAMMABLE LOGIC CONTROLLER”BACHELOR OF TECHNOLOGY

IN

ELECTRICAL & ELECTRONICS ENGINEERINGSUBMITTED

BY

PANKAJ CHAUDHARY R.N. - 24823

UNDER THE SUPERVISION OF

ARUNESH DUTTHEAD OF DEPARTMENT (HOD)

NEHRU GRAM BHARATI UNIVERSITY, ALLAHABAD

DEPARTMENT OF ELECTRICAL & ELECTRONICS ENGINEERING SANJAY GANDHI INSTITUTE OF ENGINEERING & TECHNOLOGY

Sensors Placed in the field

Automation : Typical installation . . .Automation : Typical installation . . . .Automation : Typical installation . . .Automation : Typical installation . . . .

Junction Box

Field Cabling

Control Panel

Control Hardware

SCADA Software

Communication Cable

Field Cabling

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INTRODUCTION PLC SAVE,VALVE ADDED BENEFITS PLC SYTEM CONSISTS OF INPUT DISCRETE INPUT INPUTMODULES PLC SYSTEM CONSIST OF OUTPUT OUTPUT MODULES BASIC COMPONENTS OF A PLC SYSTEM CHASSIS AND BACK PLANE EXAMPLES VARIOUS BRANDs OF PLCs

CONTENTSCONTENTS

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SCAN CYCLE OF CPU LADDER BASICS AND GATE, RELAY AND PLC EQUIVALENT OR GATE, RELAY AND PLC EQUIVALENT NOT GATE, RELAY AND PLC EQUIVALENT XOR GATE NAND GATE NOR GATE PLC PROGRAMMING SOFTWARE LADDER LOGIC EXAMPLE I/O SYSTEMs SAFETY SYSTEM APPLICATION

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IntroductionIntroduction

A PLC is a solid state / industrial computer that performs discrete or sequential logic in a factory environment. It was originally developed to replace mechanical relays, timers, counters. A sequence of instructions is programmed by the user to the PLC memory. Its purpose is to monitor crucial process parameters and adjust process operations accordingly.

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PLCPLC

A solid state device that controls output devices based on the status of inputs and a user written program. Originally developed to directly replace relays used for discrete control.

On/Off Control

Timing Counting

Sequencing Arithmetic

Data Handling

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PLC Saves

Material cost

Installation cost

Troubleshooting

Labor cost

By

Reduced wiring & associated errors

Less space

No moving parts - rugged

Possibility of reprogramming

Value added benefits

Reliability

Flexibility

Advanced Function

Communication

Speed

Diagnostics

PLCPLC

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PLCPLCPLC system consists of

Inputs

Input

Circuits

Inputs - Discrete - On/Off type

Pushbuttons

Switches

Limit Switches

Selector Switches

Proximity sensors

Photo - electric sensors

Inputs devices - Analog

RTD, Thermo - couple ….SGIET….

Discrete InputA discrete input also referred as digital input is an input that is either ON or OFF are connected to the PLC digital input. In the ON condition it is referred to as logic 1 or a logic high and in the OFF condition maybe referred to as logic o or logic low.

Normally Open PushbuttonNormally Closed Pushbutton

Normally Open switch

Normally Closed switch

Normally Open contact

Normally closed contact

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PLC

INPUTS

OUTPUTS

MOTOR

LAMPCONTACTOR

PUSHBUTTONS

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Input ModulesInput Modules

12345678910COM

A/D

con

version

To PLC

Terminal block - this is where wires from the

field devices are connected

Field device - this is showing a simple

switch

Input Module

24 Volt DC System

+ 24 Volts

- 24 Volts ….SGIET….

Input ModulesInput Modules

Pressure4-20 mA

Temperature0-10V DCSwitch

24V DC ….SGIET..

PLC system consists of

Outputs

Output Circuits

PLCPLC

Solenoids

Relays - AC or DC powered

Contactors

Motor Starters

Indication Lights

Valves

Alarms ….SGIET….

Output ModulesOutput Modules

From PLC

Terminal block - this is where wires from the

field devices are connected

Field device -Motor starter, controlling

an AC motor.

12345678910

COMD

/A C

on

version

Output Module

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Output ModulesOutput Modules

Fan120V AC

Light24V DC

Valve0-10V DC ….SGIET….

Basic Components of a PLC SystemBasic Components of a PLC System

Processor, Controller, or CPU Stores the control program and data in its memory Reads the status of connected input devices Executes the control program Commands connected outputs to change state based on

program execution

Stand alone PLCProcessor that fits in a chassis

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Basic Components of a PLC SystemBasic Components of a PLC System

Chassis/Backplane

All PLCs need some method of communicating between the controller, I/O and communications modules.

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Chassis and Backplane Chassis and Backplane ExamplesExamples

Each module plugs into the one to the left

Connections for the built in I/O

Slide modules into available slots

Example of a modular based PLC. The PLC slides into the chassis along with other modules

Example of a PLC that plugs into adjacent modules to form a backplane with no chassis required

Example of a PLC with the modules built in. Comes as one block

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Basic Components of a PLC SystemBasic Components of a PLC SystemNetwork Interface

Most PLCs have the ability to communicate with other devices. The PLC will communicate to the other devices through a network interface.

Network connecting other devices

Network interface module

PLC

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Programming/ Communication Device

Central Processing Unit (CPU)

Input

Circuits

Output Circuits

Memory

program data

Power supply

Optical isolation Optical isolation

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Various Brands of PLCsVarious Brands of PLCs

Allen Bradley USA Siemens Germany Modicon France Mitshubishi Japan GE Fanuc USA Omron Japan

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Scan Cycle of CPUScan Cycle of CPUScan Cycle Depends upon No of Scan Cycle Depends upon No of I/OsI/OsMore I/Os More scan timeMore I/Os More scan timeApplication Decides the Scan Application Decides the Scan time of a PLCtime of a PLCScan time in normal Scan time in normal applications is 1 ms to 2 ms & in applications is 1 ms to 2 ms & in bigger applications 100 ms to bigger applications 100 ms to 200 ms200 ms

Scan Cycle Depends upon No of Scan Cycle Depends upon No of I/OsI/OsMore I/Os More scan timeMore I/Os More scan timeApplication Decides the Scan Application Decides the Scan time of a PLCtime of a PLCScan time in normal Scan time in normal applications is 1 ms to 2 ms & in applications is 1 ms to 2 ms & in bigger applications 100 ms to bigger applications 100 ms to 200 ms200 ms

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Ladder BasicsLadder Basics Ladder is widely used language & is

close to Electrical basics. In 50-60% places in a ladder: NO, NC

or (XIC, XIO in case of Allen Bradley) are used.

If s/w If s/w closedclosed at this add at this add CPU interprets it as CPU interprets it as TrueTrue

conditionconditionIf s/w If s/w OpenOpen at this add at this add CPU interprets it as CPU interprets it as FalseFalse conditioncondition

If s/w If s/w closedclosed at this add at this add CPU interprets it as CPU interprets it as TrueTrue

conditionconditionIf s/w If s/w OpenOpen at this add at this add CPU interprets it as CPU interprets it as FalseFalse conditioncondition

If s/w If s/w OpenOpen at this add at this add CPU interprets it as CPU interprets it as TrueTrue

conditionconditionIf s/w If s/w ClosedClosed at this add at this add CPU interprets it as CPU interprets it as FalseFalse conditioncondition

If s/w If s/w OpenOpen at this add at this add CPU interprets it as CPU interprets it as TrueTrue

conditionconditionIf s/w If s/w ClosedClosed at this add at this add CPU interprets it as CPU interprets it as FalseFalse conditioncondition

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AND Gate, Relay and PLC EquivalentAND Gate, Relay and PLC Equivalent Boolean Expression is written as: Y = A . B

Output is high only when all the inputs are high. Therefore the AND gate is equivalent to a series combination of normally open switches.

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CONTROL SIGNAL IN1

CONTROL SIGNAL IN2

OUTPUT

0 0 0

0 1 0

1 0 0

1 1 1

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OR Gate, Relay and PLC OR Gate, Relay and PLC

EquivalentEquivalent Boolean Expression is written as: Y = A + B

In an OR gate, the output is high if any one or all of the inputs are high. Therefore the OR gate is equivalent to a parallel combination of normally open switches.Truth Table

Control signal IN1

CONTROL SIGNAL IN2

OUTPUT

0 0 0

0 1 1

1 0 1

1 1 1

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NOT Gate, Relay and PLC EquivalentNOT Gate, Relay and PLC Equivalent Boolean Expression is written as: Y = Ā

NOT Gate is an inverter and equivalent to the XIO contact in the ladder.

Control signal IN OUTPUT

0 1

1 0

Truth Table

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XOR GATEXOR GATEThe output of an XOR gate is 1 if one input is 1 &other input is 0.

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NAND GateNAND Gate The Output of a NAND Gate is 0 if both the inputs are 1. Thus a NAND Gate is equivalent to a parallel combination of Two XIO Contacts.

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NOR GateNOR GateThe Output of a NOR Gate is 1 if and only if both the

inputs are 0. Thus a NOR Gate is equivalent to a series of

combination of Two XIO Contacts.

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PLC Programming SoftwarePLC Programming Software

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Ladder Logic ExampleLadder Logic Example

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I/O SystemsI/O Systems

I/O network

Switch-input

PLC

I/O adapterInput module - distributed I/O

Local I/O

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Safety SystemSafety System

The PLC performing standard control would control the robot while it performs tasks related to producing the desired product

The safety control would monitor the light curtain to make sure that the operator never moved into the robot area while the robot was moving. If the operator broke the light curtain, the safety system would remove power to the robot so that it could not move and injure the operator

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ApplicationsPackaging Bottling & Canning

Material Handling Machining

Power Generation HVAC/ Building Automation

Security Systems Automated Assembly

Paint Lines Water treatment

IndustryCement Automobile Chemicals Plastics

Metals Paper F&B

Any application in any industry that requires electrical control

PLCPLC

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THANK YOUTHANK YOU

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