Communication method of a serially connected electronic apparatus

An electronic apparatus, from among a plurality of serially connected electronic apparatuses, which can communicate a control command signal and first and second control signals, said electronic apparatus comprising:

• a first connection unit, having an input terminal for inputting the first control signal and an output terminal for outputting the second control signal, which is connected to an electronic apparatus from among the plurality of serially connected electronic apparatuses provided at a preceding stage of connection;
• a second connection unit, having an output terminal for outputting the first control signal and an input terminal for inputting the second control signal, which is connected to an electronic apparatus from among the plurality of serially connected electronic apparatuses provided at a succeeding stage of connection;
• a processing unit having a first input terminal connected to the input terminal of said first connection unit, a second input terminal connected to the input terminal of said second connection unit, and an output terminal connected to the output terminal of said second connection unit;
• and
• a change-over switch for switching a connection of the output terminal of said first connection unit to one of the output terminal of said processing unit and the input terminal of said second connection unit,
• wherein said processing unit provides the first control signal, outputs the provided first control signal from the output terminal of the processing unit, determines whether or not the second control signal has been input to the processing unit from the second input terminal of the processing unit in response to the output of the first control signal, and controls said change-over switch in accordance with the determination.