The document provides a comprehensive overview of Programmable Logic Controllers (PLCs), including their definition, functionality, and programming languages. It discusses the need for PLCs in automation, leading manufacturers, and both their advantages and disadvantages. Additionally, it highlights practical applications in various industries and explains various PLC components and logic structures.

1. PLC (Programmable
Logic Controller)
Presented by : Mohit Ojha

2. Contents :
 What is PLC?
 Leading Manufacturers of PLC
 Need of PLC in Automation
 Block diagram of PLC
 PLC Instruction set
 Nomenclature in Programming PLC
 How it can be programmed?
 Understanding Ladder Logics
 Where to use PLC?
 Advantages
 Disadvantages

3. What is PLC?
PLC is a Programmable Logic Controller , which is in
solid state /computerized industrial controller which
performs discrete or sequential logic in industrial
environment.
It is a digital operating electronic device which consist
of internal memory to store the program to perform
specific functions such as logic , sequence , counting ,
timing etc.

4. Leading Manufacturers of PLC :

6. Need of PLC in Automation
 In automation of Industries , Plants or Processes.
 Developing a control system for controlling and monitoring
it.
 Efficient working.
 Easy and economical solutions for automation.
 Improve mass productivity of large scale industries
 Maintain the quality and quantity of material
 Avoids severe accidents and errors.
 Reduces the manpower.
 Higher accuracy in less time while production.

7. Block Diagram of PLC

8. PLC instruction set
 NORMALLY OPEN (NO) :
 NORMALLY CLOSED (NC) :
Contact State of contact Contact act as
NO
1 (ON) close switch
0 (OFF) open switch
Contact State of contact Contact act as
NC
1 (OFF) close switch
0 (ON) open switch

9.  CONTACT COIL OR OUTPUT COIL :
 INVERSE CONTACT OR OUTPUT COIL :
 SET INSTRUCTION OR SET COIL :
 RESET INSTRUCTION OR RESET COIL :

10. Nomenclature in Programming PLC :
Nomenclature Stands for
M Memory bit of internal memory
X Physical Inputs of PLC
Y Physical Outputs of PLC
T Internal Timers
C Internal Counters
S SET
R RESET
F For designing a Function Block

11. How it can be Programmed?
PLC programming languages :
 Graphical languages :
 Ladder Logic Diagram (LD)
 Function Block Diagram (FBD)
 Sequential Function Chart (SFT)
 Text based languages :
 Instruction list (IL)
 Structured text (ST)

12. Understanding Ladder Logics :
A B O/P
0 0 0
0 1 0
1 0 0
1 1 1
A B O/P
0 0 0
0 1 1
1 0 1
1 1 1
A B O/P
0 0 1
0 1 1
1 0 1
1 1 0
A B O/P
0 0 1
0 1 0
1 0 0
1 1 0
A B O/P
0 0 1
0 1 0
1 0 0
1 1 1
A B O/P
0 0 0
0 1 1
1 0 1
1 1 0
AND gate : OR gate : NAND gate :
NOR gate : EX-OR gate : EX-NOR gate :
A O/P
0 1
1 0
NOT gate :

13. Where to use PLC?
 Textile Industries :
 Automatic Jigger Dyeing Machine
 Speedframe Machine automation
 Other Industries :
 Pump and Motor Control applications
 Cooling towers
 Water level controller and monitoring
 Automation of flood gates of Dams etc.

14. Automatic Electronic Jigger Dyeing
Machine

15. Speedframe Machine automation

18. ADVANTAGES :
 Faster scan time.
 Intelligent input/output modules.
 High speed
 Reliable
 Minimum maintenance.
 Flexibility in programming and reprogramming.
 Small in size.
 Easier modification.
 A wide range of control application.
 Capable to communicate with computers in plant.
 Troubleshooting programs in easy which reduces downtime.

19. DISADVANTAGES :
 Some PLC’s turn ON , when the power is restored which may
cause any accident.
 For specific small scale industries electromechanical systems
like Relay based systems are less costly than PLC.
 PLC gets affected under high temperature, vibrations
conditions but both of these can be overcome while
installation of PLC.

20. THANK YOU ...!!!