In the PLC, CPU module what role?

plc cpu module is the control center of the PLC. It functions in accordance with the procedures given PLC system receives and stores from the programmer type of user programs and data; check the power supply, memory, I / O and watchdog timer status, and can diagnose the user program syntax error. I / O module is the interface between PLC and site control interface input channels. Power module plays an important role in the overall system. If you do not have a good, reliable power system is not working properly, so the manufacturers of the PLC power supply design and manufacturing very seriously. Programming plays a role in the design and commissioning of the plc. Now a lot of free online plc programmable software available.