CAN-Bus (Functional Description)

CAN-Bus

The CAN-bus (Controller Area Network) is a serial bus system, in which all connected stations are equally entitled, i.e. each control unit can both send as well as receive. In other words, the connected control units can "communicate" and exchange information via the lines.

Due to the linear structure of the network, the bus system is fully available for all other control units in the event of one control unit failing. The connection consists of two data links (CAN-L and CAN-H) which are interface-protected by means of shielding (CAN-S).

The EGS, ASC/DSC control units, digital motor electronics and the instrument cluster are currently interconnected with this system. Linking-in of further control units will follow. The following signals are exchanged between EGS, ASC/DSC, DME control units and instrument cluster via the CAN bus:
- Accelerator pedal position
- Load signal
- Engine speed
- Engine coolant temperature
- Brake switch signal
- Kick-down signal
- Driver program
- Gear
- Engine intervention
- Wheel speeds
- Selector lever position and program information display
- Transmission control fault indicator
- Kilometer reading

The connected control units must all have the same CAN status. The CAN status can be checked via the diagnosis interface. The CAN status (bus index) is specified in the identification of the relevant control unit connected to the CAN-bus.