Patent ID: 7307994

Claim:
A communication system, comprising a plurality of bus-connected nodes, each node having a unique node ID, wherein, when a collision occurs between message packets transmitted from the nodes, a message packet with an arbitration field indicating a node ID with a highest priority flows through a bus ahead of any other colliding message packet, wherein each of the nodes comprises: a transmitting node ID writing unit that writes its own node ID as a transmitting node ID into an arbitration field of a message packet to be transmitted to the bus; a destination node ID writing unit that writes a node ID of a destination node into an auxiliary field defined at a predetermined location in the message packet; a transmitting unit that transmits to the bus the message packet in which the transmitting and destination node IDs are written; a determination unit that determines, based on a comparison between its own node ID and a node ID indicated in an arbitration field of a message packet existing on the bus, whether or not the message packet is to be received; and a receiving unit that receives the message packet if the determination unit determines that the message packet is to be received, wherein the communication system further comprises a control unit comprising: a receiving unit that receives a message packet transmitted from one of the nodes; a rewriting unit that rewrites the received message packet by replacing the node ID written in the arbitration field with the node ID written in the auxiliary field; and a transmitting unit that transmits the rewritten message packet to the bus.