Can-C And Can-IHS Networking Management

The BCM is the Network Manager (NM) for the CAN-C and CAN-IHS that can be awakened by the bus and as well as it can wake up the bus if necessary while the ignition is off, and the SGW is the Non-Networking Manager. The CAN-C and CAN-IHS have Slave ECUs with classifications for communicating.

A Slave ECU that can be  awakened by the bus and as well as they can wake up the bus if necessary  while the ignition is off are listed as follows:

• CAN-C
  • Steering Column Control Module (SCCM)

• CAN-IHS
  • Ambient Lighting Module (ALM)
  • Amplifier (AMP)
  • Compact Disc Module (CDM)
  • Display Screen Module (DSM)
  • Driver Door Module (DDM)
  • Driver Seat Module (DSM)
  • Integrated Center Stack (ICS)
  • Rear Cabin Comfort Controls (RCCC)
  • Intrusion Transceiver Module (ITM)
  • Passenger Door Module (PDM)
  • Power Lift Gate Module (PLGM)
  • Passenger Seat Module (PSM)
  • Seat Message Module Driver (SMMD)
  • Seat Message Module Passenger (SMMP)
  • Trailer Tow Module (TTM)

A Slave ECU that cannot be  awakened by the bus nor wake up the bus while the ignition is off are listed as follows:

• CAN-C
  • Night Vision Processing Module (NVPM)
  • Occupant Classification Module (OCM)

The communication protocol being used for the CAN data bus is a non-proprietary, open standard adopted from the Bosch CAN Specification 2.0b. The CAN-C and CAN-ePT bus systems are the same speed and the faster of the three primary buses in the CAN bus system, providing near real-time communication (500 Kbps). CAN-IHS communicates at (125 Kbps).

The CAN bus ECUs are connected in parallel to the two-wire bus using a twisted pair, where the wires are wrapped around each other to provide shielding from unwanted electromagnetic induction, thus preventing interference with the relatively low voltage signals being carried through them. The twisted pairs have between 33 and 50 twists per meter (yard). While the CAN bus is operating (active), one of the bus wires will carry a higher voltage and is referred to as the CAN bus (+) wire, while the other bus wire will carry a lower voltage and is referred to as the CAN bus (-) wire. Refer to the CAN Bus Voltages table.

The CAN-IHS bus network remains active until all ECUs on that network are ready for sleep. This is determined by the network using tokens in a manner similar to polling. When the last ECU that is active on the network is ready for sleep, and it has already received a token indicating that all other ECUs on the bus are ready for sleep, it broadcasts a bus sleep acknowledgment  message that causes the network to sleep. Once the CAN-IHS bus network is asleep, any ECU on the bus can awaken it by transmitting a message on the network. The BCM will keep either the CAN-C or the CAN-IHS bus awake for a timed interval after it receives a diagnostic message.

In the CAN system, available options are configured into the BCM at the assembly plant, but additional options can be added in the field using the diagnostic scan tool. The configuration settings are stored in non-volatile memory. The BCM also has two 64-bit registers, which track each of the as-built  and currently responding  ECUs on the CAN-C, and CAN-IHS buses. The BCM stores a Diagnostic Trouble Code (DTC) in one of two caches for any detected active or stored faults in the order in which they occur. One cache stores powertrain (P-Code), chassis (C-Code) and body (B-Code) DTCs, while the second cache is dedicated to storing network (U-Code) DTCs.