Signal processing device

A signal processing device that mediates communication between an electric apparatus that operates on a downstream side of a communication system and an apparatus control device that controls one or more of the electric apparatuses on an upstream side, the signal processing device comprising:

• a superposing circuit that generates a superposed signal obtained by superposing a data signal indicative of prescribed information on an operation signal in accordance with a state of operation elements of the electric apparatuses or an operation signal for controlling the operation elements;
• an information storage part that stores the prescribed information;
• a signal transmission terminal that inputs/outputs the operation signal or the superposed signal to/from the electric apparatuses or the apparatus control device;
• and
• an information transmission terminal that inputs/outputs the prescribed information to/from an information transfer device which executes at least one of reading of the prescribed information stored in the information storage part and writing of the prescribed information in the information storage part,
• wherein the signal processing device is connected to an external device including the electric apparatuses, the apparatus control device, and the information transfer device via a connector member, and
• the signal transmission terminal and the information transmission terminal are provided in areas that are inside the connector member in a state where the signal processing device is connected to the external device via the connector member.