US Patent 11695590 Communication device, communication system and message arbitration method

A communication device that can prevent the transmission of a message from being continuously hindered over a long period of time, a communication system and a message arbitration method are provided. The communication device transmits and receives a message to and from another device connected to a common communication line which comprises a calculation unit that calculates as to a message to be transmitted a margin time before a time when a transmission of the message is completed; a transmission unit that transmits the message to which information related to the margin time calculated by the calculation unit is attached; and an arbitration unit that performs arbitration based on the information attached to the message when simultaneous message transmissions to the communication line occur, and as to multiple of messages simultaneously transmitted to the communication line, the arbitration unit performs arbitration in such a manner as to prioritize a message with a shorter margin time.