MULTIPLEX COMMUNICATION SYSTEM GENERAL


  1. OUTLINE


    1. The multiplex communication system uses 4 communication protocols (CAN, LIN, AVC-LAN and MOST) to achieve a streamlined wiring harness configuration.

      Protocol Outline
      Controller Area Network (CAN)

      CAN is classified into 2 types according to communication speed. High Speed CAN (HS-CAN) is used for the powertrain, chassis and body electrical systems, and Middle Speed CAN (MS-CAN) is used for the body electrical system.


      • The HS-CAN portions are the CAN V bus, sub bus 2 and sub bus 13 .The network gateway ECU is used to transmit data between the buses.

      • The MS-CAN portion is referred to as the CAN sub bus 1. The main body ECU (multiplex network body ECU) 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 LIN bus for each respective body electrical system.
      Audio Visual Communication-Local Area Network (AVC-LAN) AVC-LAN is used for communication only between audio visual system components.
      Media Oriented System Transport (MOST) MOST is used for communication only between audio visual system components.

    2. Due to the introduction of the CAN communication system for the powertrain, chassis and body electrical systems, the wiring harness configuration has been streamlined.

    3. There is no direct communication between CAN, LIN, AVC-LAN and MOST networks because these multiplex communication systems are incompatible. CAN, LIN, AVC-LAN and MOST are separate networks. Because of this, some ECUs serve as gateways for the transfer of data, allowing communication between CAN and LIN networks.

    4. A customizable body electrical system is used, enabling some of the control functions of the ECUs to be set using the Global TechStream (GTS). For details, refer to the Repair Manual.

      Tech Tips

      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.

      A01GVVBE04

    5. Differences between CAN, LIN, AVC-LAN and MOST


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

      2. Compared to LIN and AVC-LAN, 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 and chassis control systems. These systems require large amounts of data to be transmitted in short periods of time.

      3. MOST is used to transmit control information, audio, video and date in real time.

        Protocol CAN LIN AVC-LAN MOST
        HS-CAN MS-CAN
        Communication Speed 500 kbps* 250 kbps* 9.6 to 20 kbps* Max. 17.8 kbps* Max. 50 Mbps*
        Communication Wire Twisted-pair Wire AV Single Wire Twisted-pair Wire Shielded Twisted-pair Wire
        Drive Type Differential Voltage Drive Single Wire Voltage Drive Differential Voltage Drive Differential Voltage Drive
        Data Length 1-8 Byte (Variable) 2, 4, 8 Byte (Variable) 0-32 Byte (Variable) 0-128 Byte (Variable)

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

      4. A twisted-pair of wires is used for CAN and AVC-LAN communication. A single Automobile Vinyl (AV) wire is used for LIN communication.

        Communication Wire Outline
        Twisted-pair Wire A01GVEN 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.
        AV Single Wire A01GVJE 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".
        Shielded Twisted-pair Wire A01GVRW This communication wire is a shielded 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.