MULTIPLEX COMMUNICATION SYSTEM GENERAL


  1. OUTLINE


    1. The multiplex communication system uses the following communication protocol:


      1. The Controller Area Network (CAN) is used for communication between the engine, chassis, and body electrical system.

    2. HS-CAN (high speed) is used for the CAN.

  2. MAIN FEATURES


    1. Multiplex communication uses serial communication data that consists of bits and frames in order to exchange information between the various ECUs. This allows a reduction of the amount of wiring used in the vehicle.


      1. A bit is the basic unit of communication used to represent the information. A bit is represented by binary values of "0" or "1".

      2. A frame is a body of data transmitted together. A frame contains a header that indicates the beginning, and an end message that indicates the end.

        A01EZ77E01

    2. Differences between Types of CAN


      1. The CAN protocol is the rule for establishing data communication. If the ECUs in the network use different frameworks for their data, such as communication speed, communication wire, and signals, they will be unable to understand each other. Therefore, a protocol (rule) must be established among them.

      2. The CAN is able to transmit larger amounts of data faster than other protocols. This feature makes it possible to transmit data accurately in the engine, chassis, and body electrical system, which requires large amounts of data to be transmitted in short periods of time.

        Protocol CAN (ISO Standard)
        Communication Speed

        500 kbps*/HS-CAN (High Speed)

        250 kbps*/MS-CAN (Medium Speed)

        (Max. 1 Mbps*)
        Communication Wire Twisted-pair Wire
        Drive Type Differential Voltage Drive
        Data Length 1-8 Bytes (Variable)

        Tech Tips

        *: bps is an abbreviation of "Bits Per Second", indicating the number of bits that can be transmitted per second.

    3. Communication Wire


      1. A twisted pair of wires is used for CAN communication. A single Automobile Vinyl (AV) wire is used for LIN communication.

        Communication Wire Outline
        Twisted-pair Wire A01EZIV This communication wire is a pair of twisted wires. Communication is driven by applying different voltages to the 2 lines in order to send a single signal. This system, which is called a "Differential Voltage Drive", reduces noise.
        A01EZCLE01