PROGRAMMABLE LOGICAL CONTROLLER PLC PRESENTED BY Mrs Bindu

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

INDEX Introduction PLC Basics PLC and Controls History Advantages of PLCs PLC Operation Comparison to Relay Logic Applications Conclusion

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.

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

BASIC PLC OPERATION PLCs consist of input modules or points, a Central Processing Unit (CPU), and output modules or points.

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).

PLC AND CONTROLS HISTORY Large amount of work required connecting wires Difficulty with changes or replacements Difficulty in finding errors; requiring skillful/experienced work force When a problem occurs, hold-up time is indefinite, usually long o Too many moving parts

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

COMPONENTS CPU Memory Areas Circuits to input or output data Basically, a big box of math

SPECIFIC COMPONENTS • Input Relays (contacts) • Internal Utility Relays • Output Relays (coils) • Counters • Data Storage • Timers

PLC OPERATION Continually scans ladder diagram Consists of 3 important steps

PLC SCAN: -

LADDER LOGIC • Definition • Comparison to Relay Logic

DEFINITION One form of drawing electrical logic schematics Very popular for PLCs Originally invented for use with relays

COMPARISON TO RELAY LOGIC First used for technicians, electricians & engineers Still first choice for most technicians, electricians, etc.

RELAY LOGIC LADDER LOGIC

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

• Two status indicators added • 6 additional wires

PROGRAMMING Basics – NO/NC Contacts/Coils AND & OR Gates Timers and Counters Building a PLC Ladder Logic Programming

BASICS NO Contact NO Coil (Output) NC Contact NC Coil (Output)

AND GATE

OR GATE

TIMERS Very simple concept, it times 2 basic types, ondelay and off-delay Still sends logic as its output

COUNTERS Counts number of times a lever is pulled, a button is pushed, etc. 3 types Up Counter Down Counter Up-Down Counter

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

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

APPLICATIONS: Manufacturing Industry Food Industry Textile Industry Plastics Industry And many other……

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

THANKS Q&A