Description:  Normally open interface maximum load: AC 250V/10A, DC 30V/10A.  SMD optocoupler isolation, strong driving capability, stable performance; trigger current 5mA.  Fault-tolerant design, the relay will not move even if the control line is broken.  Power indicator (green), relay status indicator (red).  The interface is designed humanized, and all the interfaces can be directly connected by wiring terminals, which is very convenient.     Two module interface:  1. DC+: Connect the power supply positive pole (voltage 3.3V).  2. DC-: Connect the power negative pole.  3. IN: Low level (3.3V) control relay pull in.     Relay output terminal:  1. NO: Relay normal open, the relay suspends before pulling in, and then short-connect with the COM.  2. COM: Relay common interface.  3. NC: Relay normal close, short connected with COM before pulling inand suspended after pulling in.     Package Included:  20 x 1 Channel 3.3V Relay Module