What is PLC?

 PLC is a solid state device which control output device based which control output device based on input device and user developed program. It performs relay equivalent functions.Modern PLCs can perform complex operations like PID control and Analog signal processing.


 Advantages of PLC over relay logic.

Cost effective.
Easy maintenance
User friendly
Easy programming
Easy troubleshooting

Components of a PLC

CPU (Central processing unit )
I/O Modules (Input ouput module)
Communication module

PLC programming languages

Ladder logic
Functional block diagram
Structured test
Sequential flow chart
Instruction list

Download free PLC programming software with Simulator
Next blog post is about “How to do ladder logic programming in allen bradly PLC.

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7 thoughts on “Basic Concept of PLC (Programmable logic controllers).

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  2. A Programmable Logic Controller program is generally executed repeatedly as long as the controlled system is running. The status of physical input points is copied to an area of memory accessible to the processor, sometimes called the "Input/Output Image Table"

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