A1 Instrument cluster
A6 STH heater unit
N2/7 Restraint systems control unit
N10/1 Driver-side SAM control unit with fuse and relay module
N10/2 Rear SAM control unit with fuse and relay module
N10/11 Passenger-side SAM control unit
N22 AAC [KLA] control and operating unit
N22/7 Comfort AAC control and operating unit
N25/7 HS [SIH] and seat ventilation control unit
N26/9 Special vehicle multifunction control unit (SVMCM)
N32/1 Driver front seat adjustment control unit with memory
N32/2 Front passenger front seat adjustment control unit with memory
N62 PTS control unit
N69/1 Door control unit front left
N69/2 Door control unit front right
N69/3 Door control unit rear left
N69/4 Door control unit rear right
N72 Lower control panel control unit
N72/1 Upper control panel control unit
N73 EIS [EZS] control unit
N80 Steering column module
N82 Battery control unit
N93 Central gateway control unit
N99 DC/DC converter control unit
CAN B Controller Area Network bus Class B (interior compartment) (CAN-B)
CAN-C Controller Area Network bus Class C (engine compartment) (CAN-C)

Networking of control units on CAN-B (Continuation)

M40/1 Pneumatic pump for dynamic seat control
N10/2 Rear SAM control unit with fuse and relay module
N28/1 Trailer connection unit [AAG] control unit
N70 Overhead control panel control unit
N88 TPM [RDK] control unit
N93/1 Audio gateway control unit
N121 TLC [HDS] control unit
N121/1 Rear-end door closing control unit
N130 Loading floor squib
N70 Overhead control panel control unit
N88 TPM [RDK] control unit
N93/1 Audio gateway control unit
N121 TLC [HDS] control unit
N121/1 Rear-end door closing control unit
N130 Loading floor squib

Networking of control units on CAN-C

Mfw Multifunction steering wheel
A1 Instrument cluster
A89 DTR control unit
N3/9 CDI control unit
N3/10 ME control unit
N15/3 EGS control unit
N15/5 Electronic selector lever module control unit
N15/6 Automated manual transmission control unit
N47-5 ESP control unit
N51 AIRmatic with ADS control unit
N71 Headlamp range adjustment control unit
N73 EIS [EZS] control unit
N80 Steering column module
N93 Central gateway control unit
N97 Rear axle level control system control unit
N123/4 Emergency call system control unit
X11/4 Data link connector
Y3/8 Electric control unit (VGS)
CAN B Controller Area Network bus class B (interior compartment) (CAN-B)
CAN-C Controller Area Network bus class C (engine compartment) (CAN-C)
CAN-D Controller Area Network bus class D (diagnosis)
LIN Local interconnect network (LIN)

Representation of MOST
Except code (494) USA version and except code (498) Japan version

W Wake-up line
A2 Radio
A2/6 CD changer
A2/10 TV tuner
A2/56 Radio control panel and navigation unit
A34/4 Telephone interface
A35/11 Voice control system control unit
A40/3 COMAND operating, display and control unit
N41/1 Navigation processor
N93/1 Audio gateway control unit
N112 Telecommunications control unit
N123/1 Universal Portable CTEL Interface (UPCI [UHI]) control unit
CAN B Controller Area Network bus Class B (interior compartment) (CAN-B)
MOST Media Oriented System Transport (MOST)

Representation of MOST with code (494) USA version

W Wake-up line
A2/6 CD changer
A2/56 Radio control panel and navigation unit
A35/11 Voice control system control unit
A40/3 COMAND operating, display and control unit
N41/1 Navigation processor
N87/5 SDAR control unit
N93/1 Audio gateway control unit
N112 Telecommunications control unit
N123/1 Universal Portable CTEL Interface (UPCI [UHI]) control unit
CAN B Controller Area Network bus Class B (interior compartment) (CAN-B)
MOST Media Oriented System Transport (MOST)

Representation of MOST with CODE (498) Japanese version

W Wake-up line
A2/6 CD changer
A35/1 Hands-free system control unit
A40/3 COMAND operating, display and control unit
N93/1 Audio gateway control unit
CAN B Controller Area Network bus Class B (interior compartment) (CAN-B)
MOST Media Oriented System Transport (MOST)

Overall network
The further development of driver information systems as well as the spread of video-based driver-supporting systems (e.g. backup camera, ambient sensor technology), for example, are reflected in the requirements placed on bus systems.
In automotive engineering, the term "Controller Area Network (data bus/CAN bus)" means that data are exchanged between the majority of control units in a vehicle via a CAN data bus.

A CAN data bus is a data collecting line, the data of which can be used by almost all connected control units.

Function of networking
Most control units of the vehicle are linked to each other via CAN data bus systems, in other words there is no electrical connection between a sensor and the executing actuator. A corresponding CAN message is generated from the sensor signal and made available to the CAN data bus system.

The message is sent in a message-oriented or address-oriented manner and is evaluated by the respective control units; it can, however, be received by other control units and evaluated if necessary.

The corresponding actuators are then actuated by these control units. In certain cases, various received messages are also combined in a control unit to form a new message. The new message is then also available for other control units on the CAN data bus system.

Data bus systems
Basically, the following data bus systems are involved in the networking:
- Controller area network bus class B (interior compartment) (CAN B)
- Controller Area Network bus, class C (engine compartment) (CAN C)
- Controller Area Network bus class D (diagnosis) (CAN-D)
- media-oriented system transport (MOST)
- Local interconnect network bus (LIN)

The operational field is differentiated as follows:
- CAN-B links the control units of systems located in the vehicle interior (e.g. power windows, heated rear window etc.).
- CAN-C links the control units for the drive and chassis systems (e.g. engine, transmission control etc.).
- CAN-D links the central gateway control unit with the data link connector to perform diagnosis on all networked control units.
- MOST links the control units of the audio systems and navigation systems (e.g. telephone, voice control etc.) via a fiber optic cable.
- The LIN bus is used where rather simple control and monitoring tasks are to be performed in the vehicle.

Higher requests are placed on the CAN -C with regard to immunity to interference, e.g. with respect to electromagnetic effect or radiation and the high data transfer rate.

CAN bus systems
The CAN bus systems are two-wire bus systems. They differ from one another in terms of transfer rate. CAN-B is the slower bus.

MOST bus
The MOST bus is an optical bus system. Here the data are transferred via fiber optical cables to the connected control units for information, navigation, and communication systems. It has the fastest transfer rate.

LIN
The LIN is a single-wire bus system. Compared to the other bus systems, the LIN is slow. It is used between the multifunction steering wheel and the steering column module (N80).

Data exchange between data bus systems
The radio or the COMAND operating, display and control unit forms the interface (gateway) for data exchange between the MOST and CAN-B. The central gateway control unit (N93) is the interface for data interchange between the CAN B bus and CAN C bus. At the same time, it is the interface via CAN-D to the data link connector X11/4), in order to test the control units connected to the different bus systems using STAR DIAGNOSIS.

The steering column module, instrument cluster (A1) and EIS [EZS] control unit (N73) are connected both to CAN-B and CAN-C. However, they do not act as an interface (gateway) between the two data bus systems. The steering column module reads in the switch actuations on the steering column module and all button actuations on the multifunction steering wheel (MFL) over the LIN bus and places them on the CAN-B. The steering wheel angle is recorded by the steering angle sensor (N49) and sent over the steering column module to the CAN-C.

Data exchange procedure using wheel speed sensing for navigation as an example
The COMAND operating display and control unit (A40/3) requires the wheel speeds from the left front rpm sensor (L6/1) and the right front rpm sensor (L6/2).

The "wheel speed" and "wheel rotation direction" signals of the left front rpm sensor and right front rpm sensor are read in via discrete lines by the ESP, SPS [PML] and BAS control unit (N47-5). The "wheel speed" and "wheel rotation direction" signals are processed in the ESP, SPS [PML] and BAS control unit and placed as a CAN message on the CAN-C. The central gateway control unit (N93) operates as an interface (gateway) and transmits the CAN message to the CAN-B.

If necessary the COMAND operating, display and control unit picks up the message via the interface (gateway) of the audio gateway control unit (N93/1) and processes it. The instrument cluster is likewise able to pick up this CAN message and to process it.

GF00.19-P-0001T Overall Network (GVN) Function