CPU (central processing units) which is also known as the processor, is the most important part of a PLC. Similarly, the CPU units/processor is the core component in PCs.
Without a CPU unit/processor, a PLC cannot perform its action. If the processor of the PLC stops working, then the PLC is of no use anymore.
Different techniques are used to fully utilize a PLC processor. If the processor of the PLC remains idle then the efficiency of the PLC is compromised which is not bearable in large industries.
Different PLCs come with different CPU units. The type varies from device to device. If the PLC is being used at a big scale then a PLC with a big CPU unit is used and if the CPU unit is being used at a small domestic level or
in a small processing unit then a PLC with a small CPU unit is purchased.
The CPU or the processor of the PLC is used to determine the different aspects of a PLC like memory available, different programing functions available, processing speed, and the size of the application logic available. Understanding a processor is a difficult task, however, the working algorithms and the topologies of a processor can be mastered to use it efficiently.