Module interface: Input section: DC(+): Positive power supply (by relay voltage power supply) DC(-): Connect power negative CH1: 1 relay module signal to trigger the end (high level trigger effective) CH2: 2-channel relay module signal to trigger the end (high level trigger effective) CH3: 3 relay module signal to trigger the end (high level trigger effective) CH4: 4-channel relay module signal to trigger the end (high level trigger effective)