Dedicated Short-Range Communications (DSRC), function - GF82.88-P-2001RFJ

Model 205 with code 498 (Japanese version) with code 531 (COMAND APS) Dealer option

Fig 1: Dedicated Short-Range Communications - Function Diagram

Courtesy of MERCEDES-BENZ USA

Function requirements for Dedicated Short-Range Communications in general

Circuit 15 R ON (from electronic ignition lock control unit via user interface CAN)
Transport mode not active
Electronic Toll Collection System (ETC) card inserted

Dedicated Short-Range Communications in general

The Dedicated Short-Range Communications (DSRC) system combines the following functions:

Payment of toll fees from the vehicle in the Electronic Toll Collection (ETC) system
Use of Vehicle Information and Communication System (VICS) services in 5.8 GHz reception range

The ETC system includes not only payment at the tollbooth but also a detailed list of payments made, which is created in the head unit.

The services provided through the VICS include, e.g.:

Warning of obstacles in stretch ahead
Information on traffic conditions in stretch ahead
Warning if separate lanes are merged in the stretch ahead
Electronic direction signs
Messages from the disaster early warning system (e.g. earthquake and Tsunami warnings)

Function sequence for Dedicated Short-Range Communications

The DSRC antenna and the Dedicated Short-Range Communications control unit are installed in the vehicle for transmitting and receiving data. The DSRC antenna allows the Dedicated Short-Range Communications control unit to communicate with the tollbooth and to receive the VICS information in the 5.8 GHz range.

A special ETC card is required for the ETC system and it has to be inserted in the Dedicated Short-Range Communications control unit.

All information concerning the user and the fees that have already been paid are stored on this card.

At the vehicle side, the Dedicated Short-Range Communications control unit is connected to the head unit via a universal serial bus (USB) interface. The acoustic signals, voice outputs, traffic information and display messages as part of the ETC and VICS functions are forwarded to the head unit via this connection. The head unit forwards the audio signals to the speaker system. On vehicles with code (810) Sound system, the head unit forwards the audio signals via MOST to the sound system amplifier control unit which actuates the speaker system.

The display screen picture signals are received as follows:

Head unit →

Low voltage differential signal (LVDS) line →

Audio/COMAND display

More detailed information on the speaker system is available in the "Speaker output function" information.

In the following cases, an ETC message is output over the speaker system and at the same time shown on the Audio/COMAND display:

ETC card not inserted
ETC card read error
ETC card not accepted
ETC card reader error
Fault in the communication with the tollbooth
Detailed information about recent toll payments available
Payment completed successfully (beep)

In the following cases, the LED shows an error on the Dedicated Short-Range Communications control unit (LED flashes red):

Invalid ETC card inserted
ETC card not inserted correctly
Malfunction of the ETC card reader

If an ETC card is inserted and the Dedicated Short-Range Communications control unit does not recognize an error, the LED is lit in green.

Electrical function schematic for Dedicated Short-Range Communications	PE82.88-P-2059-97FBA
Overview of system components, telematics	GF82.85-P-9999RF