MULTIPLEX COMMUNICATION SYSTEM GENERAL 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.

      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.

    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 and LIN networks because these multiplex communication systems are incompatible. CAN and LIN are separate networks. Because of this, certification ECU (smart key ECU assembly) serves 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.

      Tip:

      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.

      Y100125E28

    5. Differences between CAN and LIN

      1. Protocols, which are the rules for establishing data communication, differ between CAN and LIN. 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, 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.

        Protocol

        CAN

        LIN

        HS-CAN

        Communication Speed

        500 kbps*

        9.6 to 20 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)

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

      3. 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

        Y122977

        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 the effects of electrical noise.

        AV Single Wire

        Y122978

        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".