MULTIPLEX COMMUNICATION SYSTEM GENERAL


  1. OUTLINE


    1. The multiplex communication system uses 2 communication protocols (CAN and LIN) to achieve a streamlined wiring harness configuration.

      Protocol Outline
      Controller Area Network (CAN) High Speed CAN (HS-CAN) is used for the powertrain, chassis and body electrical systems. The HS-CAN consists of the V1 bus, V2 bus and power management bus. The power management control ECU with gateway function is used to transmit data between the buses.
      Local Interconnect Network (LIN) LIN is used for local area networking, in which the system has a respective bus for each body electrical system.

    2. There is no direct communication between CAN and LIN networks because these multiplex communication systems are incompatible. CAN and LIN are separate networks. Since these are separate networks, some ECUs serve as gateways for the transfer of data, allowing communication between CAN and LIN.

  2. MAIN FEATURES


    1. Multiplex Communication


      1. Generally speaking, multiplex communication refers to the use of serial communication data that consists of bits and frames in order to exchange information among various ECUs. This allows for a reduction of the amount of wiring on the vehicle. A bit is the basic unit of communication that is used to represent the information. A bit is represented by binary values of "0" or "1". For CAN communication, a differential voltage drive is used to represent the binary values of "0" or "1". This "differential voltage drive" reduces the effects of electrical interference.

        A01LPEFE02

    2. Differences between CAN and LIN


      1. The protocols, which are the rules for establishing data communication, differ between CAN and LIN. If the ECUs in the networks use different frameworks for their data, such as communication speed, communication wire and signals, they will be unable to understand each other. Therefore, protocols (rules) must be established among them.

      2. Compared to LIN, CAN features high-speed data transmission. Therefore, CAN is able to transmit larger amounts of data faster than other protocols. This feature makes it possible to transmit data accurately for the powertrain, chassis and body electrical systems, which requires large amounts of data to be transmitted in short periods of time.

        Protocol CAN LIN
        Communication Speed 500 kbps* 9.6 kbps*
        Communication Wire Twisted-pair Wire AV Single Wire
        Drive Type Differential Voltage Drive Single Wire Voltage Drive
        Data Length 1-8 Byte (Variable) 2, 4, 8 Byte (Variable)

        Tech Tips

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

      3. A twisted-pair wire is used for CAN communication. An Automobile Vinyl (AV) single wire is used for LIN communication.

        Communication Wire Outline

        Twisted-pair Wire

        A01LPNQ         		This communication wire is a pair of twisted lines. Communication is driven by applying different voltages to the two lines in order to send a single signal. This system, which is called a "Differential Voltage Drive", reduces the effects of electrical noise.

        AV Single Wire

        A01LPHL         		This is a lightweight single communication wire that consists of a single core line surrounded by insulation. Voltage is applied to this line in order to drive communication, and this system is called a "Single Wire Voltage Drive".
        A01LP9QE02