4 channel 5V relay optocoupler isolation Red board

4: 75 * 51 * 16.5MM

Module interface:
1, DC +: the positive supply (voltage relay according to the requirements)
2, DC-: negative one
3, IN: can be high or low level relay control
Relay output:
1, NO: normally open relay interfaces, floating suction before closing the relay, after the short circuit is absorbed and COM
2, COM: Common Interface Relays
3, NC: normally closed relay interfaces, COM and close the front relay short circuit, the pull vacant

High and low end trigger selection:

1. LOW when the shorting jumper is level-triggered;

2. to trigger high and high jumper shorted.