Patent attributes
In a network in which a plurality of ECUs are connected to one another with a common bus, one or more slots are allocated to each ECU in advance, and the plurality of ECUs cyclically transmit messages in an order prescribed in relation to the slots. When each ECU transmits the message related to one slot, each ECU creates and transmits a message including data to be transmitted to other ECUs, and information representing respectively a success/failure of the message reception related to other slots. Each ECU checks information of ACK field included in a message received during one cycle from message transmission related to one slot to a next message transmission related to said one slot. When the message related to one slot is not accurately received by the other ECUs, retransmits the message in the next transmission related to said one slot.