Audio 50 APS, function - GF82.61-P-0003T

MODEL 211.0/2 up to 31.5.06 with CODE (525) MB Audio 50 APS radio

Fig 1: View Of Radio Control Panel And Navigation Unit

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

The radio control panel and navigation unit (A2/56) is the central operating unit for the entertainment and communication systems within the MOST integrated in the vehicle. It has a video-capable LCD color display to output information such as operating menus and map data for navigation and the video picture. The following functions can be operated centrally:

Radio tuner
Cassette tape drive
CD disk drive
Navigation unit
RDS/TMC (dynamic navigation system, Germany)
Telematics (telephone, SMS, WAP)
Voice control

The radio control panel and navigation unit (A2/56) can be operated via three main control panels, on the left and right of the screen as well as below it, via a cross-shaped rocker button (cursor, enter) and a (volume ON/OFF). Depending on the main function group with fixed programming selected, the subfunctions appear on the display in the form of 2x3 function keys positioned at the sides of the screen.

Some functions can be activated using the left multifunction steering wheel button group (S110) and the right multifunction steering wheel button group (S111). It should be remembered in this case that all button operations are first processed by the instrument cluster (A1).

The instrument cluster (A1) links the incoming keypresses to the current menu setting on the multifunction display (A1p13). If necessary, it sends a corresponding CAN message via the audio gateway control unit (N93/1) to the radio control panel and navigation unit (A2/56). As an option, the vehicle can be equipped with an infrared remote control for operating from the rear compartment and with code (813) voice control system (VCS) for the telephone/audio functions. This again increases the operator convenience. The following conditions must be in effect for startup:

Circuit 15R ON
Voltage not to high or too low
System check (authentication) positive

MOST

The digital components of the radio control panel and navigation unit (A2/56) are linked to each other by the MOST (Media Oriented Systems Transport).

The network system is used to transmit data (control commands and useful information) between the various system components. Both control data as well as the actual audio signals are transmitted. Because some of the individual components work with different data formats or require different data transfer rates and security levels, different bus systems have been installed:

MOST (Media Oriented System Transport)
CAN-B (CAN interior)
CAN-C (CAN engine compartment)

Data are exchanged over MOST between the audio gateway control unit (N93/1), the radio control panel and navigation unit (A2/56), the CD changer (A2/6), the telecommunications control unit (N112) and the voice control system control unit (A35/11).

Interfaces

The CAN interior (CAN-B) is used for data exchange with the instrument cluster (A1). This is how the instrument cluster (A1) receives the audio, telephone and navigation data for the multifunction display (A1p13) in the instrument cluster (A1) and the time via the audio gateway control unit (N93/1) and the radio control panel and navigation unit (A2/56).
The time synchronization between the radio control panel and navigation unit (A2/56) and the instrument cluster (A1) can also take place via the multifunction steering wheel.
The data read in by the ESP control unit (N47-5) (e.g. left front RPM sensor (L6/1) and right front RPM sensor (L6/2)) for dead-reckoning and therefore position finding, are transmitted on the engine compartment CAN (CAN-C). The central gateway control unit (N93) transmits this information on the CAN interior (CAN-B), which is then placed via the audio gateway control unit (N93/1) on the MOST and made available to the navigation processor.

Switch on/off behavior, function

GF82.85-P-2006T