If the input of the module is set to the "normally open inspection line" state input, the end of the module input line (away from the module terminal) must be connected in parallel with a 4.7kΩ termination resistor, and if the module input terminal is set to the "normally closed inspection line" state, the end of the input line of the module input line (away from the module terminal) must be connected in series with a 4.7kΩ termination resistor. When the module is an active output, a 4.7kΩ termination resistor should be connected in parallel at the active output and an IN4007 diode in series.