100% and high qualityRelay Shield (ie 5V Quad Relay Module) is a small current signal control power equment commonly d electronic module, enabling high-power single- control devices are widely d in SCM system to e smart home project; and can be directly plued into the compatible the of various types of s, eliminating the patch cable troubles.Module features are as follows:1. Standard For Shield interfaces and shape2. Can continue to stack other For expansion boards3. 3 screw positioning holes for easy installation4. High Drive (5V or 3.3V) normally open contact closure5. Onboard relay indicator (red)Special Note: When using the board connected to it, beca USB interface is extremely high, should avoid green terminals are shorted its shell.Relay Shield Interface: (the last ture show)Relay: sky- 5V DC relay , model HJR-4102-L-5V, which Relay1 behalf of the 1st relay , the other and so on.Power Interface : 5V DC power interfaceIndicator: four lights are red when the relay is driven high , the corresponding indicator will light up .Relay Terminals: Terminal high-power , high-current high voltage can be connected to the device . The 1st foot ( i.e. NOx) is a normally open pin , NCx pin is normally closed , COMx is common, i.e., when the relay is not driven , NOx and COMx open between two pins , NCx and COMx connection ; When the relay (x) control signal pin is high drive relays , NOx and COMx connection open between NCx and COMx.