Communication device and communication system for handling communication error of superimposed signal

A communication system comprising:

• an electrical device;
• and
• a communication device configured to mutually communicating with the electrical device, wherein the communication device comprises:
• a superimposed signal receiving circuit that receives a data signal related to the electrical device as a signal superimposed on an operation signal output from the electrical device or an operation signal input to the electrical device;
• a period determination circuit that determines whether or not a communication error of the data signal detected by the superimposed signal receiving circuit occurs in a transition period of a value of the operation signal;
• and
• a state determination circuit that determines a state of communication with the electrical device in accordance with the determination by the period determination circuit,
• wherein the period determination circuit determines whether or not the communication error occurs in the transition period in accordance with a continuation time that the communication error is successively detected,
• wherein the period determination circuit regards the communication error as having occurred in a period other than the transition period in a case in which the continuation time is greater than a first predetermined threshold value, and
• the state determination circuit determines that there is a possibility that a problem has occurred in the state of the communication with the electrical device in a case in which the period determination circuit regards the communication error as having occurred in a period other than the transition period,
• wherein the state determination circuit determines that a problem has occurred in the state of the communication with the electrical device in a case in which the continuation time is greater than a second threshold value that is greater than the first threshold value.

A communication device configured to mutually communicating with an electrical device, the communication device comprising:

• a superimposed signal receiving circuit that receives a data signal related to the electrical device as a signal superimposed on an operation signal output from the electrical device or an operation signal input to the electrical device;
• a period determination circuit that determines whether or not a communication error of the data signal detected by the superimposed signal receiving circuit occurs in a transition period of a value of the operation signal;
• a state determination circuit that determines a state of communication with the electrical device in accordance with the determination by the period determination circuit;
• and
• a transition period start detection circuit that detects a start of the transition period,
• wherein the period determination circuit regards a predetermined period from the start of the transition period as the transition period and determines whether or not the communication error occurs in the transition period, and
• the state determination circuit determines that no problem has occurred in the state of the communication with the electrical device in a case in which the period determination circuit regards the communication error as having occurred in the transition period,
• wherein the state determination circuit determines the state of the communication with the electrical device in accordance with a continuation time or a number of times that the communication error is successively detected in a case in which the period determination circuit regards the communication error as having occurred in a period other than the transition period.