To provide an auxiliary unit capable of reducing the number of signal lines for outputting warning information. A multi-output unit is connected to a plurality of sensor units via individual output lines 262a to 262h through which the plurality of sensor units output a detection result of each of the plurality of sensor units and a data line 261a for communicating with the plurality of sensor units. The communication control unit 104 communicates with each of the plurality of sensor units via the data line 261a and receives warning information transmitted by at least one of the plurality of sensor units. When receiving the warning information from at least one of the plurality of sensor units via the data line 261a, the common signal line 154 outputs a common output signal indicating the warning information to an external device.