PLC module is a module that makes each functional unit of PLC into a building block, and can be combined according to the needs to meet various needs.

Programmable logic controller (PLC)

Programmable logic controller (PLC) is a digital operation electronic system specially designed for application in industrial environment. It adopts a kind of programmable memory, in which the instructions of logical operation, sequence control, timing, counting and arithmetic operation are stored, and various types of mechanical equipment or production processes are controlled through digital or analog input and output.

principle of operation

When the programmable logic controller is put into operation, its working process is generally divided into three stages, namely, input sampling, user program execution and output refreshing. The completion of the above three stages is called a scanning cycle. During the whole operation period, the CPU of the programmable logic controller repeatedly executes the above three stages at a certain scanning speed.

Functional characteristics

(1) high reliability. Because most PLCs adopt single-chip microcomputers, the integration is high, and the corresponding protection circuit and self-diagnosis function improve the reliability of the system.

(2) Easy programming. PLC programming mostly uses relay control ladder diagram and command statements, and its number is much less than that of microcomputer instructions. Except for medium and high-grade PLCs, there are only about 16 small PLCs in general. Because the ladder diagram is vivid and simple, it is easy to master and use, and even can be programmed without computer expertise.

(3) Flexible configuration. Because PLC adopts the building block structure, users can flexibly change the function and scale of the control system only by simple combination, so it can be applied to any control system.