Controlled Area Network "CAN" Line

The use of the CAN Line for data communication has been expanded with the M73 M5.2 systems. The number of signals being transmitted, as well as the number of control modules, on the CAN line has increased.

On the E38 750iL a total of five control modules communicate over the CAN line:




The table depicts the reduction of sensors and input signals required for each separate control system.

The addition of the ASC and AGS control modules to the CAN line reduces the number of hard wires and connectors required for signal communication within the powertrain system. All ASC signalling for slip control between the ASC - DME - EML and AGS control modules takes place over the CAN line.

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 stations in the event of one station failing. The connection consists of two data links (CAN_L and CAN_H) which are interface-protected by means of shielding (CAN_S).

At present, the control units adaptive transmission control AGS, digital motor electronics DME, electronic throttle control EML and dynamic stability control DSC are interconnected with this system.

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 on the identification of the relevant control unit connected to the CAN-bus.

A large number of information items such as CAN statuses or operating variables such as engine speed and temperature, are exchanged between the control units via the CAN-bus.