PURPOSE: To realize a positive and efficient address setting and further to keep positively a set self address even if a power supply for a device is turned off by a method wherein each of control devices is provided with a communication protocol means of striking sensing multiplex accessing system, a temporary address generating means, a self address setting means and a non-volatile memory means.

CONSTITUTION: A protocol processing circuit 20 is set at a receiving mode only for a specified period of time after sending a communication packet and waits for a receiving of a response packet from another control device. Upon receiving the response packet, an address multiplexing sensing circuit 23 outputs a signal instructing an address adding process to a temporary address processing circuit 24 in response to a signal R from a communication packet decoding circuit 21. After incrementing for the temporary address TA, the temporary address processing circuit 24 outputs again a new temporary address TA to the communication packet generating circuit 22. In turn, when there is no receiving of a response packet from another control device and a signal NR is outputted from the packet decoding circuit 21, the address multiplexing sensing circuit 23 sets the temporary address TA as a final self address FA and stores it in a non-volatile memory 25.