CAN COMMUNICATION SYSTEM(w/ Central Gateway ECU) SYSTEM DESCRIPTION


  1. BRIEF DESCRIPTION


    1. The Controller Area Network (CAN) is a serial data communication system for real time application. It is a vehicle multiplex communication system which has a high communication speed and the ability to detect malfunctions.

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    2. Using the CANH and CANL bus lines as a pair, CAN communication is performed using a voltage differential. (A base voltage is applied to the pair of lines and a voltage differential is created when communicating.)

    3. Many ECUs or sensors installed to the vehicle operate by sharing information and communicating with each other.

    4. 2 resistors which are necessary for communication are used in a CAN bus main line.

  2. DEFINITION OF TERMS

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    1. Central bus


      1. The central bus is a generic name for multiple subordinate CAN bus lines on the central gateway ECU (network gateway ECU).

        Tech Tips

        A bus is displayed as Bus on the "Communication Bus Check" screen of the GTS.

    2. Sub bus


      1. A sub bus is a bus that has a gateway function equipped ECU in order to communicate with the central bus and other sub buses.

        Tech Tips


        • A sub bus is displayed as Sub bus on the "Communication Bus Check" screen of the GTS.

        • When Sub bus is selected on the "Communication Bus Check" screen, ECUs and sensors connected to non-CAN networks such as LIN may also be displayed in addition to the ECUs and sensors connected to sub buses in the CAN network.

    3. Local bus


      1. A local bus is a bus that does not have the ability to communicate with other buses. ECUs and sensors on a local bus can only communicate with other ECUs and sensors on the same bus.

        Note

        Gateway function not equipped ECU is a generic name for ECUs not connected to the central gateway ECU (network gateway ECU) with a gateway function.

    4. CAN J/C


      1. A CAN junction connector is a connector that connects branch lines to a main bus.

    5. Main bus


      1. A main bus line is the wire harness that runs between the 2 terminating resistors of a bus.

    6. Branch


      1. A branch line is a wire harness that connects an ECU or sensor to a main bus line.

    7. Terminating resistors


      1. Terminating resistors which maintain a stable signal inside the CAN bus are installed. 2 resistors of 120 Ω each located at each end of the bus are necessary.


        • except Diagnosis Bus:

          2 resistors of 120 Ω each located at each end of the bus are necessary.

        • for Diagnosis Bus:

          1 resistor of 60 Ω located at end of the bus are necessary.