Programmable Logic Controller (PLC), used for controlling machine and its equipment. By the name of PLC, we can separate its operation basic three ways. First part is programming with some logic in second and third is controlling. So make a program with logic and PLC will control the machine by your logic.
PLC is a kind of computer but please don’t mix with the household personal computer. PLC is one kind of special computer that will give you perfect accuracy for operation and it will not hang or perform an automatic restart.
So we can’t compare PLC to our regular computer. Another day I will discuss the difference between PLC with our regular computer.
What is a Programmable Logic Controller?
Now come to the, What is Programmable Logic Controller (PLC)? A programmable logic controller or a PLC or a programmable controller is one kind of industrial digital type computer but different from home computer which has been ruggedized and adapted for the controlling the manufacturing processes like an assembly lines, controlling robotic devices or any processes activity that requires high reliability of control and ease to programming with process fault troubleshooting.
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Application of Programmable Logic Controller (PLC): Every modern machine has PLC to control its function or processes. Even for the PLC has some different type. Like Siemens, Logo PLC is a small type PLC and you cannot extend its input and output number.
But if we come to the Siemens S7-200 PLC then we can add some module and can increase its input and output number. And for Siemens S7-300 PLC is modular type PLC where we can easily add input and output modules for perfect operation. If you find any of the PLC in your machine then you can easily understand how many input and output required to controlling your machine.
Some machine manufacture already built their very own controlling system and they called it by a different name like PCB-XXX but their working principle is same as PLC. We can add a Human Machine Interface (HMI) with PLC and control our machine with real-time monitoring.
If you are now then I am going to give you an example then you can understand PLC operation clearly. Suppose we have a conveyor belt which carrying Coca Cola can at the packing section.
Now we will pack 12 Coca Cola can in a single box. But remember our conveyor belt is moving continuously. So we need to stop conveyor belt motor when we count 12 Coca Cola can at packing point and we can count 12 Coca Cola can by a sensor. Inside PLC we can add a counter by programming.
If one Coca Cola can pass in front of sensor it will count one. When sensor count 12 Coca Cola can then PLC will stop the conveyor belt motor for 5 seconds ( We can delay as much we need ) then conveyor belt motor will start again. This is a simple application of PLC operation.
It can be more complex by our required process. In my next post, I will discuss, What is inside in a typical PLC?
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