PROGRAMMABLE LOGICAL CONTROLLER (PLC) PRESENTED BY:- Mrs. Bindu Thakral And Jaidev Singh

1. PROGRAMMABLE LOGICAL CONTROLLER (PLC) PRESENTED BY:- Mrs. Bindu Thakral And Jaidev Singh

2. Index • Introduction • PLC Basics • PLC and Controls History • Advantages of PLCs • PLC Operation • Comparison to Relay Logic • Applications • Conclusion

3. Introduction • Programmable Logic Control, or PLC as it is universally called, is the ‘work horse’ of industrial automation. • A PLC is used to control, time and regulate the sequence. • Many production processes are controlled using PLCs like – metal machining sequences, product assembly lines and batch chemical processes.

4. PLC Basics • Programmable Logic Controllers (PLCs), also referred to as programmable controllers, are in the computer family. They are used in commercial and industrial applications

5. Basic PLC Operation • PLCs consist of input modules or points, a Central Processing Unit (CPU), and output modules or points.

6. Basic PLC Operation (cont..) • Pushbuttons (sensors), in this simple example, connected to PLC inputs, can be used to start and stop a motor connected to a PLC through a motor starter (actuator).

7. PLC and Controls History • Large amount of work required connecting wires • Difficulty with changes or replacements • Difficulty in finding errors; requiringskillful/experienced work force • When a problem occurs, hold-up time is indefinite, usually long • Too many moving parts

8. Advantages of PLCs • Number of wires reduced by approximately 80% • Fast and easy error detection. • No change in wiring to change program • Needs fewer spare parts • Cheaper when large number of I/O instruments are needed • Less moving parts • Compact • Cost effective for installation/maintenance

9. Components • CPU • Memory Areas • Circuits to input oroutput data • Basically, a big box of math

10. Specific Components •Input Relays (contacts) •Output Relays (coils) •Data Storage •Internal Utility Relays •Counters •Timers

11. PLC Operation • Continually scans ladder diagram • Consists of 3 important steps

12. Plc scan:-

13. Ladder Logic •Definition •Comparison to RelayLogic

14. Definition • One form of drawing electrical logic schematics • Very popular for PLCs • Originally invented for use with relays

15. Comparison to Relay Logic • First used for technicians,electricians &engineers • Still first choice for most technicians, electricians, etc.

16. Relay Logic Ladder Logic

17. •“Jog” function added to previous relay circuit •1 component added •3 wires added

18. •Two status indicators added •6 additional wires

19. Programming • Basics – NO/NC Contacts/Coils • AND & OR Gates • Timers and Counters • Building a PLC Ladder LogicProgramming

20. Basics • NO Contact • NO Coil (Output) • NC Contact • NC Coil (Output)

21. AND Gate

22. OR Gate

23. Timers • Very simple concept, it times • 2 basic types, on- delay and off-delay • Still sends logic as its output

24. Counters • Counts number of times a lever ispulled, a button ispushed, etc. • 3 types • Up Counter • Down Counter • Up-Down Counter

25. Building a PLC/Ladder Logic Program • To illustrate, will start in relay logic, convert to ladder logic at end • Will need to remove/replace some components

26. Relay Logic converted to Ladder Logic Diagram • Much fewer hard wired components • Double Pole Pushbutton for Jog switched toSingle Pole • Instead of motor relays, PLC just checks state of motor output

27. Applications:- • Manufacturing Industry • Food Industry • Textile Industry • Plastics Industry • And many other……

28. Conclusion :- We can conclude that • A lot of wiring work have been reduced • Error detection has became fast and easy • Size has been reduced • Cost effective for installation/maintenance

29. THANKS Q&A