Hi friends, today I’m going to give info about PLC.
A PLC is the acronym of Programmable logic controller. The advent of the PLC began in the 1970s and today in the world of automation; the PLC has become a standard for control. Control engineering has evolved over a long period of time. In the past, humans were the main for controlling a system. As the technology developed electricity has been used for control. One such is relay which allows power to be switched ON & OFF without a mechanical switch. The development of low cost computer has brought the most recent revolution called PLC.
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| Block diagram of PLC |
What a plc is?
A PLC is a user friendly microprocessor based circuit that is used to conduct multiple and complex operations.
- A PLC is essentially microprocessor or microcontroller based. It has multiple inputs and outputs. It functions according to the software.
- PLC monitors crucial process parameters and controls the process operations accordingly.
- The PLC replaces much complicated wiring by a single circuit.
- The input to the PLC can also be taken from analog devices or discrete (on off) devices.
- The PLCs have tremendous computing capacity but at the same time its size is very compact.
- Ladder Diagram is primarily used to develop software for programmable logic controllers (PLCs) used in industrial control applications.
Now let’s see what are the advantages of the PLC system:
- PLCs are highly flexible.
- They have compact size and reduced cost.
- PLCs are accurate, high speed and reliable.
- PLCs can be reprogrammed easily & quickly.
- Data storage and logging is easier since PLCs can be easily interfaced to computers.
- PLCs can handle large number of inputs and outputs.
- Programming of PLCs is easier.
Disadvantages:
- For small operations or one or two functions, PLCs are not cost effective.
- PLCs use electronic devices and microprocessors. They fail sometimes in adverse environmental conditions.
- If operation is never altered, PLCs prove to be costly.
A few examples of ladder diagrams are:
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| Ladder diagram for Stair case controller |
I hope u all enjoyed this…. Keep visiting!!
