GF54.00-P-0005BK CAN Data Bus, Function

GF54.00-P-0005BK CAN Data Bus, Function







CAN stands for "Controller Area Network". This is an electrical bus system for carrying data over two wires.

The tasks are:
- Data transfer between individual control units
- Readying sensor signals for several systems
- Reducing the number of electric cables
- Improve electromagnetic compatibility.

The CAN data bus consists of a special twisted two-core data line that connects all CAN users (control units) in parallel.

The two lines of the data line must not be mixed up (LOW-/HIGH- level). The ME control unit always represents a terminal with regard to bus adaptation.

A 120 Ohms terminating resistor is therefore installed in the motor electronics control unit.

The data are transmitted digitally over the CAN databus at various intervals. The individual data blocks are defined in a data protocol and it is specified which data are received or transmitted by a control unit.

Each connected control unit is able to transmit or receive data (bidirectional bus). The sum of the data blocks, the short break between two transmission intervals and additional properties of the CAN data bus are checked constantly. Detected faults are stored and placed in the fault memory.

In the vehicle a distinction is made between a fast engine CAN data bus (CAN CLASS "C") for the drive and chassis systems and the slightly slower body CAN data bus (CAN CLASS "B") for the vehicle interior.

The interface of the two CAN data buses (gateway) takes place in the central gateway control unit (N93), which also represents the interface between the control units on the CAN data bus and the line to the data link connector (X11/4) for STAR DIAGNOSIS.

When a control unit is replaced, the new control unit must be coded again.
This control unit coding is via a menu of the STAR DIAGNOSIS menu.

CAN data bus, see also wiring diagrams.

The international standardized network management "OSEK" (open systems and their interfaces for electronics in vehicles) is used for all control units on the CAN data bus.