Patent ID: 6856623

Claim:
A communication system including a plurality of subscriber-side units manufactured by respective desired vendors and a station-side unit manufactured by a desired vendor accommodating the subscriber-side units, the station-side unit being capable of carrying out a broadcast communication with all of the subscriber-side units by sending a broadcast message in a manner of broadcast communication, the station-side unit comprising: a broadcast message generating unit generating a broadcast message; and a group designating message generating unit for generating a group designating message to be broadcast to all of the subscriber-side units and having designation information to designate some of the subscriber-side units as a component constituting a group of units which are to receive the broadcast message, and the subscriber-side unit comprising: a broadcast message processing unit receiving and processing the broadcast message from the station-side unit; and a state control unit controlling, in response to a reception of the group designating message having the designation information designating the subscriber-side unit broadcast from the station-side unit, a status of the reception and the processing for the broadcast message in the broadcast message processing unit to a valid status; whereby only subscriber-side units having a valid status are allowed to receive and process the broadcast message generated by the station-side unit, and wherein the station-side unit designates some of the subscriber-side units manufactured by an identical vendor as a component constituting the group of units.