CAN data bus, function - GF54.00-P-0005AQ
MODEL 209 with ENGINE 156.982
CAN stands for " C ontroller A rea N etwork". 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
- Improving the electromagnetic compatibility (EMC)
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 level/high level). The ME control unit always represents a terminal with regard to bus adaptation.
A 120 Ω terminating resistor is therefore installed in the motor electronics control unit.
The data are transmitted digitally over the CAN data bus 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 the two transfer intervals and other properties of the CAN data bus are checked constantly. Detected faults are stored and placed in the fault memory.
In the vehicle, a differentiation is made between the fast (500 kbit/s) drive CAN data bus for the engine, transmission and chassis systems and the slow (83.3 kbit/s) interior CAN data bus for the systems in the vehicle interior.
Additionally, a diagnosis CAN data bus with a speed of 500 kbit/s is also available for vehicle diagnosis.
The interface between the three CAN data buses (Gateway) is located in the EIS [EZS] control unit.
The instrument cluster and steering column module are connected to both the interior CAN data bus and the drive CAN data bus, and they exchange data with both data bus systems. However they do not serve as an interface (Gateway) between the two data bus systems
When a control unit is replaced, the new control unit must be coded again.
A STAR DIAGNOSIS menu is used here for control unit coding.
The international standardized network management "OSEK" (O
pen systems and their Interfaces for E
lectronics in motor vehicles) is used for all control units of the CAN data bus.
| ME-SFI [ME] control unit, component description | GF07.61-P-6000AMG |