It is an OMRON 5V 240V solid state relay 2A, output with resistance type fuse 240V 2A. The input control signal voltage for the relay module is: (the state of the 0-2.5V low-level relay OFF; the state of the 3-5V high-level relay ON).

Low-level trigger refers to the signal triggering voltage between the end and the negative electrode of the power supply is OV, or trigger terminal voltage lower voltage than the positive power supply voltage, low to can trigger, make the relay, is usually the cathode of the power supply and the triggering end of a trigger mode connection, so that the relay is attracted.

It has the blue KF301 terminal is connected to the line of control.