Interconnection of local communication bus system

A local communication system comprising:

• a. two or more clusters of stations each cluster comprising a plurality of stations interconnected for communicating messages via a respective data bus and in accordance with a respective set of communication protocols, at least one of the respective sets of communication protocols being a first set of communications protocols;
• b. a further data bus for interconnecting the clusters, the further data bus not supporting the first set of communication protocols;
• c. a plurality of respective gateway devices, one for each cluster, the gateway devices linking the clusters and the further data bus and being operable to enable communications therebetween;
• wherein
• the first set of communications protocols specifies a maximum time for reply by a first station to a message sent by a second station;
• and
• each respective gateway device that is coupled to a cluster using the first set of communications protocols is configured (I) in response to a message originating station within that cluster, to generate and send a temporary response to the message originating station within a predetermined period less than the specified maximum response time, pending arrival of a response from a message destination station outside that cluster, (ii) during said pendency provide for passage of a message to or from another station of that cluster, and (iii) upon arrival of said response from said message destination station, pass said response to the message originating station
• in which a nominated station (the "AV Center")
• has knowledge of signal paths in the cluster containing the message originating station;
• uses control messages to establish a signal path between the message originating station and the respective gateway device for the cluster containing the message originating station;
• and
• provides information to cause establishment of signal paths
• between the message destination station and the respective gateway device for the cluster containing the message destination station;
• and
• between the cluster containing the message originating station and the cluster containing the message destination station via the further bus.

A gateway device for use in a local communication system, the system including

• a plurality of stations interconnected for communicating messages via a first data bus and in accordance with a first set of communication protocols, and
• at least one further station not supporting said first set of communication protocols;
• and wherein
• said first set of communication protocols specifies a maximum time for reply by a first station to a message sent by a second station;
• said gateway device comprising
• means for linking said first data bus and said further station to enable communication therebetween, and
• means whereby when a message requiring a response is originated by a station of said plurality of stations and passed to said further station via said gateway, said gateway device (i) generates and sends a temporary response to the originating station within a predetermined period less than the specified maximum response time, pending arrival of a response from said further station, (ii) during said pendency, provides for passage of a message to or from another station of the plurality of stations, and (iii) upon arrival of said response from said further station, passes said response to said originating station.