I have mentioned this (somewhere, 'issue' or email) before, but I actually happened to find a 16 channel module that works with the HW-584 board without any modification, and it's probably one of the ...

A relay module is an electrical component. Various industries use this circuit board that houses one or more electric switches or relays in different circuits and electrical projects. Relay boards are ...

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 ...