PROGRAMMABLE LOGIC CONTROLLERS

Workshop on

“PLC Basics & Programming”Prepared by- Rahul N Deshmukh Asst Professor E&TC Dept

Content-• History• Basics of Programmable Logic Controller (PLC)• PLC hardware & software• Inputs/Outputs• PLC Programming Languages• What is an Automation?• Supervisory Control & Data Acquisition System (SCADA)

Rahul N Deshmukh E&TC Dept SSBT's COET Bambhori Jalgaon

History-In 1968, a group of engineers from General Motors developed the

concept of PLC with an initial specification. The PLC must be:

i . Easy to program.ii. Not need rewiring the control system if change the program.iii. Smaller in size, cheaper and high reliability.iv. simple construction and low maintenance v. Cost- competitive


Development -• Manual• Contactor & relay based• Logic gates• Microcontroller based• Programmable Logic Controllers• Touchscreen & Wireless PLC’s


Advantages of PLC- • Less wiring. • Wiring between devices and relay contacts are done in the

PLC program. • Easier and faster to make changes. • Trouble shooting aids make programming easier and reduce

downtime. • Reliable components make these likely to operate for years

before failure.


PLC Size-• 1. SMALL - it covers units with up to 128 I/O’s and

memories up to 2 Kbytes. - these PLC’s are capable of providing simple to

advance levels or machine controls.• 2. MEDIUM - have up to 2048 I/O’s and memories up to 32

Kbytes.• 3. LARGE - the most sophisticated units of the PLC family.

They have up to 8192 I/O’s and memories up to 750 Kbytes.

- can control individual production processes or entire plant.


Applications-• Manufacturing / Machining• Food / Beverage• Metals• Power• Mining• Petrochemical / Chemical


Programmable Logic Controller

CPU

The Basic Block

Inputs Outputs

What is PLC?


What is PLC?


PLC Construction-Compact PLC Modular PLC


Some PLC’s-• 80% market is covered by

Siemens PLC• Modicon is a first PLC

invented in france• Messung & Delta are India

made PLC’s

Allen Bradley Siemens

Modicon Mitsubishi

Schneider Electric Messung


Block Diagram of PLC-


PROCESSOR

POWERSUPPLY

I MN O P D U UT L E

O M U OT DP UU LT E

PROGRAMMING DEVICE

From SENSORSPushbuttons,

contacts,limit switches,

etc.

ToOUTPUT

Solenoids, contactors,

alarmsetc.

Functional Interaction of PLC system-


Rack & Rail System in PLC-


What is PLC?


network

digital inputs

digital outputs

analog inputs / outputs

Siemens S7-200 PLC Configuration-


Siemens S7-200 CPU-


Siemens PLC expansion Module-


Siemens PLC Status Indicator-


Siemens PLC CPU Internal Circuitry-


Digital Input Circuitry-


Physical Wiring Input Side-


AC input module DC input module

DC Inputs (Source/Sink)-


Sinking input module/sourcing input device Sourcing input module/sinking input device

Digital Outputs-



Digital Output Logic-

Physical wiring Output Side-



Analog Input-


Physical Wiring PLC analog Input-


Analog Input example-


Analog Output-

Physical Wiring PLC analog Output-


Analog Output example-


• Switches and Pushbuttons• Sensing Devices

• Limit Switches• Photoelectric Sensors• Proximity Sensors

• Condition Sensors • Pressure Switches• Level Switches• Temperature Switches• Vacuum Switches• Float Switches

• Encoders

What are inputs?


• Valves• Motor Starters• Solenoids• Actuators• Control Relays• Horns & Alarms• Stack Lights• Fans• Counter/Totalizer• Pumps• Printers

What are outputs?


Contactor & Relay-


Contactor Relay

Input Connection-


Output Connection-


PLC Scan Cycle-


PLC Manufacturers

Allen Bradley PLC (America)

Siemens PLC (Germany)


Modicon PLC (France)

Crouzet PLCGE Fanuc (Japan & America)


• Delta PLC (India)

• Messung PLC (India)

• Mitsubishi (Japan)


PLC Hardwire System


S1

S2

K1

S1 S2

PLC

K1

Hardwire PLC

0 V

24 VDC

K1

L

N

S7-300 PLC Wiring Diagram


PLCProgramming Languages

Types of Programming Software Languages

• Ladder Logic (LL)

• IEC Format• Function Block Diagram (FBD)• Structured Text (ST)• Instruction List (IL)• Ladder Diagram (LD)• Sequential Function Chart (SFC) - also known as “Grafcet”


Ladder Logic

Read / Conditional Instructions

Write / Control Instructions

| | |/|

| | |/|| |

| | |/| ( )

| |

| |

Start (Rung #1)

End (Rung #4)

( )

( )

( )

Inputs Outputs


Siemens S7-200 I/O Configuration-


Addressing System Input & Output-


Input-

Output-

Function Block Diagram (FBD)


Structured Text (ST)


Instruction List (IL)


Ladder Diagram (LD)


Sequential Function Chart (SFC)


PLC Software View


PLC Program example-

eg- Lamp Glows when input switch is activated



eg- to start & stop the motor



eg- to stat the motor


Latching Condition-


PLC Programming(Siemens S7-300)

Hardware-Siemens S7-300Software-Simatic Manager

-80% market occupied by Siemens-STEP-5 & STEP-7 available with Siemens-I/O Capacity (S7-200 )-32 analog & 256 digital (S7-300)-256 analog & 1024 digital (S7-400)-1500 analog & 128000 digital


Hardware-Siemens S7-300Software-Simatic Manager

Steps for creating programming window (OB-Organization Block)

-Install Simatic Manager V-5.5 Software-for (Simulation) install PLCSim v-5.1


Addressing System for S7-300


What is an Automation?

• Automation is a delegation of human control to the machine• For e.g-


PLC Implementation-


ANY QUIRY….??

Thank you

PROGRAMMABLE LOGIC CONTROLLERS

Engineering

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