Comand System Function

The following systems can be controlled centrally with the aid of the cockpit management and data system (COMAND):
- Radio
- Cassette player
- CD player with changer (optional)
- Sound system (optional)
- Navigation
- Telephone (optional)
- Television (TV) (optional)






Block diagram of overall COMAND system illustrated with the following equipment:
- Sound system (code 810)
- Voice control system (VCS) (code 813b)
- CD player with changer (code 819)
- TV system (code 860)
- Rear monitor (code 861)

Abbreviations
- A2/12 = Rear wondow antenna amplifier module
- X11/4 = Data link connector

The COMAND operating, display and control module (A40/3) is the central component for the COMAND system. It has a video compatible LCD color display for output of information such as control menus, map data for navigation and television picture. Control is possible with permanent function keys and menu guidance on the display

Some functions can be activated in addition with the help of the switches on the multifunction steering wheel. In this case it must be remembered that when a button is actuated on the multifunction steering wheel affecting the COMAND system, the signal first travels as a CAN message from the jacket tube module (N80) to the instrument cluster (A1). The instrument cluster (A1) links the incoming key signals with the current menu setting on the multifunction display and then relays the corresponding CAN message to the COMAND operating, display and control module (A40/3).

As an option the vehicle can also be equipped with an infrared remote control system for control from the rear passenger compartment and with the voice control system (code 813b) again increasing the operating convenience.

COMAND bus system
The digital COMAND components are linked with one another by a bus system. Data (control commands and utility information) is transferred between the individual system components by the bus system. Since some of the individual components operate with different data formats or have varying requirements regarding the transmission rate and reliability, various bus systems are installed (see block diagram):
- Digital data bus (D2B)
- CAN (passenger compartment)
- CAN (COMAND)

Data between the external audio components, the telephone system and, if present the voice control system is exchanged via the D2B bus (fiber optic cable bus). Here control data as well as the actual audio signals (music from CD changer, voice for telephone) are transmitted.

Connection to other control modules in the vehicle (instrument cluster (A1), jacket tube module (N80),...) is possible via the CAN (passenger compartment) bus.
For example the instrument cluster (A1) receives the audio, telephone and navigation data as well as the time from the COMAND operating, display and control module (A40/3) via this bus.

The CAN (COMAND) bus is independent of the CAN (passenger compartment) bus and serves for data exchange between the COMAND operating, display and control module (A40/3) and the optional components such as the TV tuner (A2/42)(not from beginning of introduction). Moreover, the COMAND central computer is linked with the navigation processor (A40/3n2) via this bus (see block diagram).

NOTE: The protocols for the CAN (passenger compartment), CAN (COMAND) and CAN (telephone) buses are different, i.e. not compatible (see block diagram of interlinkage). This means that a CAN message present on the CAN (passenger compartment) bus is not necessarily available on the CAN (COMAND) bus as well.