IN - This pin is also called the control pin because it is used to control the output of the relay. COM - is connected to the device you intend to connect. NC - terminal is connected to the COM ...

This was formerly stated to be for the SainSmart relay modules, but it was later pointed out to me that these boards actually already have this logic built in to them. 8 12kΩ ¼ Watt Resistors This ...