GF82.85-P-0003TXU Cockpit Management and Data System (COMAND), Function

GF82.85-P-0003TXU Cockpit Management And Data System (COMAND), Function

Component Identification:

The COMAND operating, display and control unit (A40/3) can be used to operate the following systems centrally:
^ Audio systems (e.g. radio tuner, CD)
^ Navigation system (with code (530) COMAND APS USA (with navigation system))
^ Telephone system
^ Sound system
^ Voice control system (VCS [SBS])

In vehicles as from 1.6.05, audio CDs in MP3 format can also be played back in the CD disk drive integrated into the COMAND operating, display and control unit and the CD changer.

The COMAND operating, display and control unit is the central component in the COMAND system. It has a color liquid crystal display (LCD) with video capability for displaying information such as operating menus and map data for navigation. Operation is by permanently assigned function keys and 2 rotary switches as well as menu-assisted on the LCD color display.

Some functions can also be activated with the aid of the pushbuttons on the multifunction steering wheel (MFL). Here it should be noted that all button actuations on the MFL are initially processed by the instrument cluster (A1). The instrument cluster links the incoming button actuations with the current menu configuration on the multifunction display (A1p13) and, where applicable, it sends a corresponding Controller Area Network (data bus/CAN bus) (CAN) message to the COMAND operating, display and control unit.

Networking of the components of the COMAND system
The digital components of the COMAND operating, display and control unit are networked with each other via a bus system. This bus system is used to transmit data (control commands and useful information) between the various system components. The individual component operate with various data formats and they have different request in terms of transmission rate and reliability. Thus, different data bus systems are installed.

The COMAND data bus system includes the following:
^ Media Oriented System Transport (MOST)
Data between the MOST components are sent via the MOST bus. Both control data as well as the audio signals are transmitted.
^ Controller area network bus class B (interior compartment) (CAN B)
Data exchange takes place via the CAN-B between the COMAND operating, display and control unit and the instrument cluster. Here the audio gateway control unit is the interface between CAN-B and MOST. These bus systems are used by the instrument cluster to receive the audio, telephone and navigation data from the COMAND operating, display and control unit for the multifunction display in the instrument cluster along with the time.

The "Audio AUX" function in combination with the AUX jack in the glove compartment can be used to connect additional audio sources (e.g. MP3 player, Walkman).

Data exchange between COMAND operating, display and control unit and instrument cluster
The following systems controlled by the COMAND operating, display and control unit can be operated with the aid of the buttons on the MFL and the multifunction display of the instrument cluster, and information on the systems can be called up
^ Audio systems (e.g. radio tuner, CD)
^ Navigation system (with code (530) COMAND APS USA (with navigation system))
^ Telephone system

All data are exchanged between the instrument cluster and the COMAND operating, display and control unit via the CAN-B and MOST. All the button operations on the multifunction steering wheel (MFL) are read in over the local interconnect network (LIN) bus and then sent via CAN-B to the instrument cluster. The instrument cluster links these signals with the systems currently displayed on the multifunction display (audio, navigation, telephone).

This interpretation is necessary, as the function of the buttons is dependent on the current content of the multifunction display. The interpreted data are then sent from the instrument cluster to CAN- B, forwarded to the audio gateway control unit and received from the COMAND operating, display and control unit via the MOST. Here the audio gateway control unit sets up the interface between CAN-B and the MOST.

A change of system on the multifunction display does not affect what is shown on the LCD color display of the COMAND operating, display and control unit, however the change in the display on the LCD color display of the COMAND operating, display and control unit will affect the multifunction display.

The instrument cluster receives the current time from the COMAND operating, display and control unit, since this is received automatically via the global positioning system (GPS).