The modules that make up the PLC are the hardware basis of the PLC. Only by understanding which modules the selected PLC has and their characteristics, can the modules be correctly selected to form a complete PLC to meet the requirements of the control system for PLC.
Common PLC modules are:
CPU module, which is the hardware core of PLC. The main performance of PLC, such as speed and scale, is reflected by its performance.
Power module, which provides internal working power for PLC operation, and some can also provide power for input signals.
I/o module, which integrates i/o circuits and is divided into modules of different specifications according to the number of points and circuit type.
Memory module, which mainly stores user programs, and some also provide auxiliary working memory for the system. In structure, memory modules are attached to CPU modules.
Base plate and rack module, which provide base plate for the installation of PLC modules and provide bus for the connection between modules. Some backplane connections use interface modules, and some use bus interfaces. Different manufacturers or the same manufacturer but different types of PLC are not the same.
The main box of box type small PLC integrates the above modules into a box, and is divided into different specifications according to the number of i/o points that may be provided.