This presentation provides an overview of programmable logic controllers (PLCs). It discusses what a PLC is, the history and major components of PLCs. The operational sequence and common programming languages like ladder logic are described. An example is given of using ladder logic to start and stop a motor. PLCs provide benefits like reliability, flexibility, cost-effectiveness and ease of maintenance. They are widely used in industrial automation applications such as robotics, materials handling, and process control. The presentation concludes by thanking the audience.

1. PRESENTATION ON PLC
Prepared By
Neeraj budhlakoti
Roll no. NTTF-AL-
68-2019-034

2. CONTENTS
What is PLC?
History of PLC
Major components of PLC
Operational sequence of PLC
Ladder logic
Example of starting and stopping of a motor
Advantages
Disadvantages
Application

3. WHAT IS PLC
•PLC is a digital computer designed for multiple
inputs and output arrangements, extended
temperature ranges, immunity to electrical
noise, and resistance to vibration and impact. A
PLC is an example of a real time system.

4. HISTORY OF PLC
• PLC was introduced in late 1960’s
• First commercial & successful Programmable Logic
Controllers was designed and developed by Modicon as a
relay replacer for General Motors.
• Earlier, it was a machine with thousands of electronic parts.
• Later ,in late 1970’s,the microprocessor became reality &
greatly enhanced the role of PLC permitting it to evolve
form simply relay to the sophisticated system as it is today.

5. MAJOR COMPONENTS OF A PLC

6. MAJOR COMPONENTS OF PLC
Major Components of a Common PLC
POWER SUPPLY - Provides the voltage needed to run the primary PLC
components
 I/O MODULES- Provides signal conversion and isolation between the
internal logic- level signals inside the PLC and the field’s high level signal.
PROCESSOR -Provides intelligence to command and govern the activities
of the entire PLC systems.
 PROGRAMMING DEVICE- Used to enter the desired program that will
determine the sequence of operation and control of process equipment
or driven machine.

7. PLC OPERATION SEQUENCE
)Self test: Testing of its own hardware and software for faults.
Input scan: If there are no problems, PLC will copy all the inputs and
copy their values into memory.
 Logic solve/scan: Using inputs, the ladder logic program is solved
once and outputs are updated.
Output scan: While solving logic the output values are updated only
in memory when ladder scan is done, the outputs will be updated
using temporary values in memory. Self test Input scan Logic scan
Output scan

8. MARKET SHARE OF DIFFERENT PLC IN INDIA
siemens
31%
mitsubishi
12%
rockwell
automation
22%
abb
2%
fanuc
3%
schneider
8%
other
22%
MARKET SHARE OF DIFFERENT PLC IN INDIA
siemens mitsubishi rockwell
automation
abb fanuc schneider other

9. PROGRAMMING LANGUAGE OF PLC
Most common languages encountered in PLC programming are:
I. Ladder Logic
II. Functional Block Diagram
III. Sequential Function Chart
IV. Boolean mnemonics

10. USAGE OF PROGRAMMING LANGUAGE IN INDIA
60%
22%
8%
10%
usage of programming language in india
ladder logic
functional
block diagram
sequential
function chart
boolean
mnemonics

11. LADDER LOGIC
The ladder logic is the oldest programming language for PLC.
 It is well suited to express Combinational logic.
The main ladder logic symbols represent the elements : make
contact break contact relay coil
And the ladder logic is the most used language across the
world for programming

12. START STOP OF A MOTOR USING LADDER LOGIC
START STOP Q1
Q1

13. PROGRAMMING PLC

14. STARTING OF MOTOR
When the Start pushbutton is pressed, the CPU receives a logic from
input . This causes the contact to close. All inputs are now a logic . The
CPU sends a logic to output . The motor starter is energized and the
motor starts.

15. ADVANTAGE OF PLC
Reliability.
Flexibility in
programming
and
reprogramming.
Cost effective
for controlling
complex
systems.
Small physical
size, shorter
project time.
High speed of
operation.
Ability to
communicate
with computer
systems in the
plant.
Ease of
maintenance
/troubleshootin
g.

16. Disadvantages of PLC
PLC devices are proprietary it means that part or
software of one manufacturer can’t be used in
combination with parts of another manufacturer.
Limited design and cost option
Fixed Circuit Operations.
PLCs manufacturers offer only closed architectures.

17. APPLICATION OF PLC
Wherever automation is desired the PLCs are best suited to meet the
task.
Few examples of industries where PLCs are used :
1) Robots manufacturing and control
 2) Car park control
3) Train control station system
 4) Food processing
 5) Materials handling
 6)Machine tools
 7)Conveyer system etc.

18. APPLICATION OF PLC
PLCs are used in various applications in industries such as the steel industry, automobile
industry, chemical industry and the energy sector. The scope OF PLCs dramatically
increases based on the development of all the various technologies where it is applied.
In the Travel Industry, PLC has been used to monitor the safety control system and to
operate lifts and escalators.

19. THANK YOU