The functional modules of PLC (Programmable Logic Controller) usually include the following types:
1) CPU module: This is the core module of PLC, which is mainly responsible for processing input signals, executing program instructions, controlling output signals, and providing monitoring and diagnostic functions. CPU modules usually include processors, storage, and communication interfaces.
2) Input module: The input module is used to collect external signals, such as sensor signals, button signals, switch signals, etc. The input module generally includes input interface, signal processing circuit and isolation circuit.
3) Output module: The output module is used to control external equipment, such as starting the motor, controlling the lights, outputting alarm signals, etc. The output module generally includes an output interface, a driving circuit and an isolation circuit.
4) Communication module: The communication module is used to realize the data communication between the PLC system and other equipment, usually including Ethernet module, serial communication module, CAN bus module, etc.
5) Power module: The power module provides power support for the PLC system to ensure that the PLC system can work normally, usually including AC power module, DC power module, etc.
6) Bus module: The bus module is used to expand the number of input and output points of the PLC system and improve the system performance, usually including data bus module, special bus module, etc.
In addition, the PLC may also include other special function modules, such as timer module, counter module, arithmetic module, comparison module, shift register module, motion control module, security module, data storage module, etc., to meet different application needs.