The relay module is more than two electronic relays installed on the circuit board, which are input and output to the terminals through the circuit. Usually replace the intermediate relay, the relay module consists of relay, relay seat, light-emitting diode, Zener diode, current limiting group, varistor, input and output terminals, PCB board, rail mounting seat.

In the past, when we were doing automatic electrical control cabinets, the PLC control negative relay would be used to control the load. At present, industrial automation has developed in the direction of integration, followed by the development of relay modules. The coils of PLC relay modules can be directly controlled, and the corner contacts of relay modules can control the load again. The advantage is that the relay module is small in size, only accounting for 1/2 of the volume of the small intermediate relay, and the contact current is larger than that of the small relay, generally 10A, 12A, 16A, 30A with varistor, when the relay is disconnected, the spark generated The function of arc extinguishing can improve the service life of the relay.