Programmable Logic Controller (PLC)

History of the PLC

• •First Programmable Logic Controllers were designed and developed by Modicon as a relay replacer for GM and Landis.
• •These controllers eliminated the need for rewiring and adding additional hardware for each new configuration of logic.
• •The new system drastically increased the functionality of the controls while reducing the cabinet space that housed the logic.
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• •The first PLC, model 084, was invented by Dick Morley in 1969.
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• •The first commercial successful PLC, the 184, was introduced in 1973 which was designed by Michael Greenberg. 

Definition of PLC

A PROGRAMMABLE LOGIC CONTROLLER is a solid state control system that continuously monitors the status of devices connected as inputs.  Based upon a user written program, stored in memory, it controls the status of devices connected as outputs.

 

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