CAN bus

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The Controller Area Networks bus standards describe a two-wire, serial, multi-master, synchronized (but clockless), broadcast-only system designed for vehicles. CAN is one of the mandated transports for ODB-II on-board diagnostics, and is required in all US vehicles since 2008. CAN distance decreases with bit rate, but at low rates can run to the kilometers.

Standards

  • CAN-1 (1986): Original Bosch protocol
  • CAN-2.0 (1991): Bosch update, later standardized by ISO 11519 (1993)
    • CAN-2.0A (ISO 11898-3, 2006): 11-bit identifiers, up to 125Kbit/s (CAN-Lo, "Basic CAN", "Reliable CAN")
    • CAN-2.0B (ISO 11898-2, 2003, 2016): 29-bit identifiers, up to 1Mbit/s (CAN-High, "Full CAN")
  • ISO 11898-1: Data link layer common to CAN-2.0A and B
  • CAN-FD (2012): Bosch extension to CAN-2.0 for up to 64B messages + better CRC
  • ISO 15765-2 (2016): "Road vehicles: Diagnostic communication over CAN" ISO-TP L3/L4 for larger (up to 4095B) packets, 15Mbit/s