COMMUNICATION METHOD AND COMMUNICATION SYSTEM

摘要

Out of devices connected to the same power line (7), a device which has judged based on the results of noise measurement that it is difficult to continue communication in the case of the current tone-set/tone position comes to serve as a virtual master for tone change. The device serving as a virtual master transmits a tone change request command and waits for a response from another device for a predetermined time. If the virtual master device receives even one tone change rejection command during the time, the virtual master device abandons the change and ends the virtual master processing. Conversely, if the virtual master device receives no tone change rejection command in the predetermined time, the virtual master device transmits a tone change instruction command. On receiving the tone change instruction command, all the other devices currently connected change the tone at a time.