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

Control Systems TypesControl Systems Types

Programmable Logic Controllers Distributed Control System PC- Based Controls

IntroductionIntroduction

The PLC is microprocessor based specialized computer that carries out control functions of many types and levels of complexity. Its purpose is to monitor crucial process parameters and adjust process operations accordingly. It can be programmed, controlled and operated.

Applications :

Machine controls, Packaging, Palletizing, Material handling, similar Sequential task as well as Process control

Advantages of PLCs Flexibility, Reliability Large quantity of contacts Online/ offline modifications In-house simulation & testing of project Speed in operation  Ladder or Boolean programming methods  Ease of maintenance / troubleshooting  Simplicity of ordering control system components  Documentation, Security

Programmable Logic Controllers Programmable Logic Controllers

PLC Types

Nano (Small) Micro (Medium) Large

Basic criteria for PLC Types

Memory Capacity I/O Range Packaging and Cost per Point

Programmable Logic Controllers Programmable Logic Controllers

Various Brands of PLCsVarious Brands of PLCs

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

Ranges in Allen BradleyRanges in Allen Bradley

Programming Software: RS Logix 500 & Programming Software: RS Logix 500 & RS Logix 5000RS Logix 5000

PICO Mirco Logix SLC PLC Compact Logix Flex Logix Control Logix

Ranges in SiemensRanges in Siemens

PLC Programming Software

S5 Dos based S7-200 Microwin S7-300 Sematic Manager S7-400 Sematic Manager

Ranges in ModiconRanges in Modicon

PLC Programming S/W

Nano PL7 Pro Micro PL7 Pro Premium PL7 Pro Quantum Concept Atrium Concept

Types of PLCsTypes of PLCs

Compact Modular Distributed

Compact PLCsCompact PLCs

Modular PLCsModular PLCs

CPU

Power Supply I/O Modules

ATS05

STZ

10

Remote I/O 1 2 3 4

Distributed PLCs with Remote I/ODistributed PLCs with Remote I/O

ATS05ATS05 ATS05

Central Processing Unit (CPU) Input Output Modules Power Supply Bus system Programming Device

P L C Components P L C Components

CPU

PROGRAMDEVICE

IN OUT m

MODULEMODULE

It is a micro-controller based circuitry. The CPU consists of following blocks :

Arithmatic Logic Unit (ALU), Program memory Process image memory (Internal memory of CPU) Internal timers and counters, Flags CPU performs the task necessary to fulfill the PLC functions.

These tasks include Scanning, I/O bus traffic control, Program execution, Peripheral and External device communication, special functions or data handling execution and self diagnostics.

P L C : Central Processing Unit P L C : Central Processing Unit

How CPU FunctionsHow CPU Functions

Read InputsRead Inputs

Comn with NetworkComn with Network

Read User ProgramRead User Program

Up KeepUp Keep

Read RegistersRead Registers

Write to OutputWrite to OutputWrite to OutputWrite to Output

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

Features of CPUsFeatures of CPUs

Execution Speed .1 ms/1ms/10ms I/O Handling capacity Memory capacity Instruction sets (Normal, advance) Language support (FB, LD) Support for application specific module Integrated functionality

PLC Input ModulesPLC Input Modules These modules act as interface between real-

time status of process variable and the CPU Digital (Contacts, Switches, Limit switch,Push

buttons, Pressure switch, pump / valve on-off status)

Typical modules is 24 V DC, 115 V AC, 230 V AC (0 or 1, Closed or open, True or false)

Analog (Pressure, Flow, Level, Tx, RTD Thermocouple)

4-20ma, 0-10v, -10-+10v, 0-5v, 0-20ma, -20-+20ma.

Note: There are modules which can handle all are called universal modules

Digital Input ModuleDigital Input Module

No of channels: 4,8,16,32, 64 24vdc, 230v ac, 110dc Source, sink or both Isolated or un-isolated common

Digital Input Module- InternalDigital Input Module- Internal

StartStart

StopStop

S/WS/W

Current limiting resister

Current limiting resister

5v dc

5v dc

InverterInverter

O/P highO/P high

ComCom

Opto couplerOpto coupler

In case one diode is parallel to another diode in opposite polarity. It can act as source or sink both

In case one diode is parallel to another diode in opposite polarity. It can act as source or sink both

When diode conducts, infra red light falls on the base of the transistor, which conducts and inverter makes O/P high

Diode transistor pair is called optical isolation (produces 1.5kv isolation)

In case of higher voltages only card is damaged, functioning of the entire plant is saved.

NoteNoteNoteNote

120 V acL1 L2

L2

L1

1

2

3

4

PB

inputfield

device

Input moduleterminal board

Input statusindicator

Digital Input Module-External Digital Input Module-External

Digital Output ModuleDigital Output Module These modules act as link between the CPU and the

output devices in the field No of channels: 4,8,16,32, 64 24vdc, 230v ac, 110dc Solenoid Valves, lamps, Actuators, dampers, Pump/valve on

off control Isolated or un-isolated common Relay type (both ac & dc), TTL Type (only dc), Triac

type (only ac)

Note: contact life of a relay is generally 1 million operations, use of semiconductor switching in triac & TTL increases life and switching response is faster.

Note: contact life of a relay is generally 1 million operations, use of semiconductor switching in triac & TTL increases life and switching response is faster.

In Triac changing over is done at zero In Triac changing over is done at zero crossing. Advantage: Negative spikes crossing. Advantage: Negative spikes produced by inductive loads, which are produced by inductive loads, which are harmful for electronic ckts are reduced. harmful for electronic ckts are reduced. Amount of back emf is drastically Amount of back emf is drastically reducedreduced

In Triac changing over is done at zero In Triac changing over is done at zero crossing. Advantage: Negative spikes crossing. Advantage: Negative spikes produced by inductive loads, which are produced by inductive loads, which are harmful for electronic ckts are reduced. harmful for electronic ckts are reduced. Amount of back emf is drastically Amount of back emf is drastically reducedreduced

Transistor- Transistor Logic Transistor- Transistor Logic (TTL)(TTL)

Triac outputsTriac outputs

0 V0 V0 V0 V

24 V24 V24 V24 V

In dc modules a parallel In dc modules a parallel diode is placed to reduce diode is placed to reduce noise /back emfnoise /back emf

In dc modules a parallel In dc modules a parallel diode is placed to reduce diode is placed to reduce noise /back emfnoise /back emf

LoadLoad

ComCom

diodediode

ComCom

Isolated Com

Isolated Com LoadLoad

In isolated type modules In isolated type modules common is different for all common is different for all loadsloads

In isolated type modules In isolated type modules common is different for all common is different for all loadsloads

Digital Output ModuleDigital Output ModuleDigital Output ModuleDigital Output Module

Analog Input ModuleAnalog Input Module

No of channels: 2, 4,8,16 (rarely 16 channels)

Isolated or un-isolated common Type of input: Thermocouple, RTD, Voltage 2 wire, 4 wire Resolution

Analog Input ModuleAnalog Input Module

Ohm

TX

Ohm

TX

PT-100PT-100

TXTX

24V dc

24V dc

++

++

__

__

4-20 mA4-20 mA

4-20 mA4-20 mA

++

4 Wire TX

4 Wire TX

2 Wire TX

2 Wire TX

24v dc24v dc

A/D converte

r

A/D converte

r

Low pulse filter ckt

Low pulse filter ckt Scalin

g

Scaling

Note: A/D converter comes with 16, 14, 12, 18 bit resolution

Note: A/D converter comes with 16, 14, 12, 18 bit resolution

Example: Microscope’s resolution is good if we can see each part of an organism

Example: Microscope’s resolution is good if we can see each part of an organism

Analog Input ModuleAnalog Input Module

Resolution: Allen Bradley uses natural binary conversion.

Higher the resolution higher the cost & depends upon how minute data can be monitored

12 bit resolution = 4096 bits. Data to be measured will be divided into 4096 parts.

Most of Analog Input modules use 16 bit. Digital information is at bit level Analog information is at word level

Analog Output ModuleAnalog Output Module No of channels: 2, 4,8,16 (rarely 16 channels) Isolated or un-isolated common Current, Voltage Resolution 12 bit, 14 bit, 15 bit, 16 bit output is 4-20 mA, 0-10 V Ex : Control Valve, Speed, Vibration

Note: For Robotic operation you need finer control, hence needed high resolution. For Normal Control valve operation less resolution may be used

Note: For Robotic operation you need finer control, hence needed high resolution. For Normal Control valve operation less resolution may be used

Analog Output ModuleAnalog Output Module

I/P Converter

I/P Converter

++

__

D/A Converter

D/A Converter

Digital Form

Digital Form

PID Alogrithm

PID Alogrithm

Constant Current Source

Constant Current Source

50% Opening50% Opening

50% Opening50% Opening

0-327670-32767Constant current Constant current

source will give 12 source will give 12 mA for opening mA for opening

50%50%

Constant current Constant current source will give 12 source will give 12

mA for opening mA for opening 50%50%

120 V acL1 L2

L2

L1

1

2

3

4

Output statusindicator

Output field device

Module blown Fuse indicator

Output module Terminal board

Output module- Output module- connectionsconnections

Application Specific ModulesApplication Specific Modules

Stepper Control modules Servo Control modules Common modules

Modbus profibus Device Net ASi Bus (2 wire,Very high speed comn

carries power & signal both) DG Synchronization modules etc.

Sinking/SourcingSinking/Sourcing

The power supply gives the voltage required for electronics module (I/O Logic signals, CPU, memory unit and peripheral devices) of the PLC from the line supply.

The power supply provides isolation necessary to protect the solid state devices from most high voltage line spikes.

As I/O is expanded, some PLC may require additional power supplies in order to maintain proper power levels.

P L C : Power Supply P L C : Power Supply

It is path for the transmission of the signal . Bus system is responsible for the signal exchange between processor and I/O modules

The bus system comprise of several single line ie wires / tracks

P L C : Bus System P L C : Bus System

PLC CyclePLC Cycle

Outputs

Machineor

Process

Programmablecontroller

Inputs

Sense the Input Process the Logic Give Output

PLC Signal FlowPLC Signal Flow

Programming Terminal

O:0/7

O:0/7

O:1/5

Output Devices

Output ModulesProcessor MemoryInput Module

Input DevicesLadder Program

O:0/7

O:1/5

I:0/6

I:1/4

O:1/5

I:0/6

I:1/4

I:0/6

I:1/4

Data InputImage Table

OutputImage Table

PLC Architecture in 1970sPLC Architecture in 1970s

Discrete Machine Control

ProgrammingTerminal

PLC

I/O

Connection Point to Point

Programming Language :

- Relay ladder logic - Flexibility in altering - Control system operation

Connection Point to Point

Discrete and Process Control

PLC Architecture in 1980s

Reasonable ComputerRunning PLC

Programming Software

PLC

I/O

Programming Language :

- Ladder Program - PID - Data Storage

MS - DOS

PLC Architecture in 1990sPLC Architecture in 1990s

Discrete and Process Control

PC running PLC Programming Software

PLC

I/O

Connection in networked allowing Multiple PLC

PLC became a part of the developing enterprise resource system

Windows

PLC

Distributed I/O Modules

Distributed I/O modules

PLC

Distributed I/O scanner

Data Communication Bus

PLC Architecture TodayPLC Architecture Today

Remote I/O Network

SPLITTERS

FIBER OPTIC LINK

TAPS

Remote I/O

Hot Redundant System

PLC Architecture TodayPLC Architecture Today

Controller ControllerController

Controller

Workstation Workstation Workstation Workstation

Switched Hub

PLC Architecture todayPLC Architecture today

Ethernet Technology in PLCs

RemotePlatform

Wireless Modem

Wireless Modem

PLC

H M I Display

PC

PLC Architecture todayPLC Architecture today

Wireless communication

PLC

PLC Programming StandardsPLC Programming Standards

The open, manufacturer-independent programming standard for automation is IEC 61131-3. You can thus choose what configuration interface you wish to use when writing your application :

Ladder Diagram Statement List Instruction List Function Block Diagram Sequential Function Chart Structured Text

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

Comparison & use of XIO, Comparison & use of XIO, XICXIC

RelayRelayRelayRelay

StopStopStopStop

StartStartStartStart

MotorMotorMotorMotor

AuxiliarAuxiliaryy

AuxiliarAuxiliaryy

PPPP

NNNN

StartStartStartStart StopStopStopStop RelayRelayRelayRelay

AuxiliarAuxiliaryy

AuxiliarAuxiliaryy

StartStartStartStart StopStopStopStop RelayRelayRelayRelay

AuxiliarAuxiliaryy

AuxiliarAuxiliaryy

Basic Relay LogicBasic Relay Logic

Basic Start/ Stop circuit with Basic Start/ Stop circuit with latchlatch

AND Gate, Relay and PLC EquivalentAND Gate, Relay and PLC Equivalent

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

EquivalentEquivalent

NOT Gate, Relay and PLC EquivalentNOT Gate, Relay and PLC Equivalent

PSUPSUPSUPSU

CPUCPUCPUCPU

DI 16

CH

DI 16

CH

DI 16

CH

DI 16

CH

DI 8 C

H

DI 8 C

H

DI 8 C

H

DI 8 C

H

DO 16

CH

DO 16

CH

DO 16

CH

DO 16

CHPSUPSUPSUPSU

DI 32

CH

DI 32

CH

DI 32

CH

DI 32

CH

AI 4 C

H

AI 4 C

H

AI 4 C

H

AI 4 C

H

AO 4 C

H

AO 4 C

H

AO 4 C

H

AO 4 C

H

AI/AO 4

CH

AI/AO 4

CH

AI/AO 4

CH

AI/AO 4

CH

Slot 0Slot 0Slot 0Slot 0 Slot 1Slot 1Slot 1Slot 1 Slot 2Slot 2Slot 2Slot 2 Slot 3Slot 3Slot 3Slot 3 Slot 4Slot 4Slot 4Slot 4 Slot 5Slot 5Slot 5Slot 5 Slot 6Slot 6Slot 6Slot 6 Slot 7Slot 7Slot 7Slot 7

Addressing Scheme in AB PLCAddressing Scheme in AB PLC

File type: slot add .word add /bit addCPU generally is in Slot 0Slot 1 - I :1.0/0 to I:1.0/15Slot 2 - I:2.0/0 to I:2.0/7Slot 3 - O:3.0/0 to O:3.0/15Slot 4 - I:4.0/0 to I:4.0/31Slot 5 - I:5.0 to I:5.3Slot 6 - O:6.0 to O:6.3Slot 7 - I:7.0 to I:7.1

O:7.0 to O:7.1