Introduction to Programmable Logic Controller

shree ganeshy nam:
jai mataji:
jai laxmi devi:
jai sasvati devi:
A PLC is a solid state/ computerized industrial computer that performs discrete or sequential logic in a factory environment. It was originally devloped to replace mechanical relays,timers,counters.PLCs are used successfully to execute complicated control operations in a plant. Its purpose is to monitor crucial process parameters and adjust process operations acordingly. A sequence of instructions is programmed by the user to the PLC memory and when the programme is executed,the controller operates a system to the correct operating specifications.

The first PLC system evolved form conventional computers in late 60s and early 70s.these first PLCs were installed primarily in automotive plants. Traditionally the auto plant had to be shut down for up to a month at model changeover time. One of the major timeconsuming changeover procedures had been the wiring of new or revised relay 7 control panels. The PLC programming procedures replaced the rewiring a panel full of wirs,relays,timers,counters &other components replaced helped reduse the changeover time to a matter of few days.