Emergency call system, function

P82.95-3195-79

Function requirements, emergency call system, general

 Circuit 30

 Transport mode is inactive.

 The communications module of the HERMES control unit is configured with the telephone number of the relevant service provider.

Emergency call system, general

The emergency call system allows a manual or automatic emergency call to be triggered. The emergency call is received by the Mercedes-Benz Service Center. The user is spoken to in the language that is selected in the system settings of the COMAND controller unit. If necessary, the Mercedes-Benz Service Center notifies the local rescue services. If the Mercedes-Benz Service Center is not staffed, the emergency call is automatically forwarded to the local rescue services 112.

If the HERMES control unit receives the message "Circuit 15R" from the electronic ignition lock control unit via the diagnostic CAN, it checks the operational readiness of the emergency call system. After a successful check, the emergency call system is operational and "SOS ready" appears on the Audio/COMAND display. The following checks are carried out:

 Receipt of cyclic readiness signal ("sign of life") from the supplemental restraint system control unit.

 Connection to the left emergency call system antenna or right emergency call system antenna (on model 222)

 Connection to telematics services antenna (in model 217)

 Connection to the multifunction antenna (on model 222) or to the GPS antenna (on model 217)

 In the event of a fault, depending on the fault type, a fault message appears on the Audio/COMAND display and the fault code is stored in the fault memory of the HERMES control unit. If, after switching off the ignition, the Supplemental Restraint System control unit switches to the "Sleep" mode, it no longer sends a readiness signal and the "SOS NOT READY" message is shown.

The electronic ignition lock control unit sends the "Circuit 15" message over the following path:

Diagnostic CAN 

HERMES control unit

The emergency call system function comprises the following subfunctions:

 Emergency call system status indication

 Position finding

 Manual or automatic emergency call

Emergency call system status indication

The status of the emergency call system is shown in the following ways:

 Status indication on the Audio/COMAND display

 Status indication via light-emitting diode

 Status indication in instrument cluster

Status indication on the Audio/COMAND display

The status of the emergency call system is indicated by a text message on the Audio/COMAND display in the following cases:

 Emergency call system operational or not operational ("SOS ready" or "SOS not ready" in telephone menu)

 Emergency call has been activated ("activating" (call setup), "transmitting data" (data telegram transmission), "connected" (voice connection established))

 Emergency call forwarded to local 112 rescue services (the address (with code 531 (COMAND APS)) and the coordinates of the vehicle position are also shown)

 Call activation has failed several times ("MB emergency call processing failed. Please dial 112 on the mobile phone.")

If an emergency call is active, the top right of the Audio/COMAND display also shows a telephone symbol, an emergency call symbol and the field strength of the HERMES control unit.

The HERMES control unit sends the display over the following path:

Diagnostic CAN 

Electronic ignition lock control unit 

Interior CAN 

COMAND controller unit 

LVDS line 

Audio/COMAND display

Control communication (e.g. switch-on) is sent by the COMAND controller unit over the telematics CAN to the Audio/COMAND display.

Some test messages on the Audio/COMAND display can be confirmed with the Audio/COMAND control panel or the touchpad (with code 448 (Touchpad)). The Audio/COMAND control panel or the touchpad (with code 448 (Touchpad)) transmits the signals via the following route:

Telematics CAN 

COMAND controller unit 

Interior CAN 

Electronic ignition lock control unit 

Diagnostic CAN 

HERMES control unit

Status indication via light-emitting diode

The LED of the SOS button is used to indicate the following states:

 Active service, light-emitting diode flashes.

 Self-diagnosis of emergency call system, LEDs light for approx. 5 s.

 Fault in emergency call system, LEDs permanently on.

 Diagnosis

The HERMES control unit actuates the LED of the SOS button via the following route:

Diagnostic CAN 

Electronic ignition lock control unit 

Interior CAN 

Front SAM control unit 

Roof LIN 

Overhead control panel control unit

Status indication in instrument cluster

If the HERMES control unit fails, the instrument cluster shows "SOS nonfunctional". The failure of the HERMES control unit is reported over the following path:

Diagnostic CAN 

Electronic ignition lock control unit 

User interface CAN 

Instrument cluster

Position finding

The HERMES control unit takes over the position finding signals from the COMAND controller unit. The COMAND controller unit transmits the signals via a USB line (universal serial bus) to the HERMES control unit. In vehicles with code 494 (USA version), the COMAND controller unit transmits the signals via the W-LAN antenna (A2/83) to the respective interface of the HERMES control unit.

At the same time as the GPS position finding the HERMES control unit conducts a permanent basic position finding, that enables the position of the vehicle to be determined even when the GPS reception fails.

The position finding function consists of the following component functions:

 GPS position finding

 Basic position finding

GPS position finding

On vehicles with code 531 (COMAND APS), the COMAND controller unit receives the GPS signal from the multifunction antenna (on model 222) or from the GPS antenna (on model 217) via the global positioning system antenna splitter and forwards it via the following route:

Interior CAN 

Electronic ignition lock control unit 

Diagnostic CAN 

HERMES control unit

Additional function requirement for basic position finding

 Circuit 15R ON

Basic position finding

The HERMES control unit requires the following signals for basic position finding:

 Wheel speed and yaw rate signals from the Electronic Stability Program control unit

 Steering wheel angle sensor

The wheel speed and yaw rate signals are sent by the Electronic Stability Program control unit via the following route:

Chassis FlexRay 

Electronic ignition lock control unit 

Diagnostic CAN 

HERMES control unit

The signal of the steering wheel angle sensor is sent via the following route:

Steering column tube module control unit 

Chassis FlexRay 

Electronic ignition lock control unit 

Diagnostic CAN 

HERMES control unit

The HERMES control unit uses the data to calculate the current vehicle position (longitude and latitude).

 Position finding errors, rolling backwards with "circuit 15 OFF" (ignition switched off) or transport of the vehicle falsify the basic position finding. In both cases, this deviation is automatically corrected on receipt of GPS data.

 The HERMES control unit receives not only GPS signals from the COMAND controller unit, but also additional map data that also supports basic position finding.

Manual or automatic emergency call

In an emergency situation, a service receptionist from the Mercedes-Benz Service Center can obtain an overview of the condition inside the vehicle with the aid of the data received from the HERMES control unit (voice connection and data telegram) and initiate appropriate help measures. An emergency call be initiated manually or automatically. These emergency calls are made for the following reasons:

 Automatic alerting of the rescue services after an accident

 Alerting rescue services by pushing a button (own emergency situation, observed accident)

 Reduction in rescue times through fast emergency notification with details on exact location involved

 The automatic emergency call has priority over a manually triggered emergency call. If an automatic emergency call is triggered during a manual emergency call, the manual emergency call is interrupted. If a manual emergency call is triggered during an automatic emergency call, it is ignored. However, a data telegram containing updated position data is sent to the Mercedes-Benz Service Center, and the existing connection is maintained.

The manual or automatic emergency call function consists of the following subfunctions:

 Triggering of an automatic emergency call

 Triggering of a manual emergency call

 Voice connection between vehicle and Service Center

Additional function requirements for triggering an automatic emergency call

 Circuit 15 ON

Triggering of an automatic emergency call

In the event of an accident with deployment of the restraint systems (not the PRE-SAFE® system) an automatic emergency call (eCall) is immediately sent. An emergency call is sent out regardless of the severity of the accident.

The HERMES control unit receives the crash information over a direct line as a digital crash signal from the supplemental restraint system control unit.

The supplemental restraint system control unit also (redundantly) sends the crash information, including crash level, via the following route:

User interface CAN 

Electronic ignition lock control unit 

Diagnostic CAN 

HERMES control unit

 The supplemental restraint system control unit transmits a readiness signal cyclically (e. g. every 500  ms) via the same route as crash information. This enables the HERMES control unit to monitor communication with the supplemental restraint system control unit and correct operation of the crash detection.

Additional function requirements for triggering a manual emergency call

 No automatic emergency call is active.

Triggering of a manual emergency call

The manual emergency call is triggered by pressing the SOS button.

The SOS button signals are sent via the following route:

Overhead control panel control unit 

Roof LIN 

Front SAM control unit 

Interior CAN 

Electronic ignition lock control unit 

Diagnostic CAN 

HERMES control unit

Voice connection between vehicle and Service Center

Once the emergency call has been triggered, the HERMES control unit establishes a voice connection with the Mercedes-Benz Service Center.

 To achieve transmission and reception diversity, the multifunction antenna and the emergency call system antenna are used to set up the connection.

The status of the connection setup is indicated by the following messages on the Audio/COMAND display:

 "Activating" (setting up the call)

 "Sending data" (data telegram transmission)

 "Connected" (voice connection established)

 Establishing a voice connection to the Mercedes-Benz Service Center is canceled after several failed attempts to connect, and the following message is shown on the Audio/COMAND display: "MB emergency call activation failed. Please dial 112 on the mobile phone."

 To avoid any unintentional termination, the Accept/Terminate phone call button on the multifunction steering wheel is temporarily disabled while the connection is being established during an automatic emergency call.

While the connection is being set up, audio sources are muted (mute function) and existing telephone connections are interrupted.

In vehicles except code 810 (Sound system) and except code 811 (Advanced sound system), the HERMES control unit sends the signal for the mute function to the COMAND controller unit.

In vehicles with code 810 (Sound system) and with code 811 (Advanced sound system), the HERMES control unit transmits the signal for the mute function to the sound system amplifier control unit.

As soon as a connection is set up to the Mercedes-Benz Service Center, the HERMES control unit automatically sends a data telegram to the Service Center. The data telegram transmits the following data:

 Time stamp

 GPS position of vehicle

 Language

 Vehicle identification number

 MB Contact status (ON or OFF)

 Position history (Tracing of vehicle positions up to a distance of a few 100  m from current location)

 Number of vehicle occupants (estimated)

After a data telegram has been transmitted to the Mercedes-Benz Service Center, the user can speak to a service receptionist via the voice connection. The Mercedes-Benz Service Center carries out the call, where possible, in the language that was selected in the system settings of the COMAND controller unit and sent in the data telegram. The hands-free system microphone is used for the voice input. The hands-free system is not available for telephone calls throughout the duration of the emergency call.

The HERMES control unit receives the outgoing voice signals via the hands-free system microphone via the COMAND controller unit.

The HERMES control unit outputs the incoming voice signals over the center instrument panel speaker.

The voice output volume can be adjusted using the + and - button for setting specific functions and for volume adjustment found in the right multifunction steering wheel button group.

The Accept/terminate phone call button of the right multifunction steering wheel button group can be used to end the emergency call, if this is not done by the Mercedes-Benz Service Center.

The right multifunction steering wheel button group sends the control signals via the following route:

Steering wheel electronics 

Steering LIN 

Steering column tube module control unit 

Chassis FlexRay 

Electronic ignition lock control unit 

User interface CAN 

Instrument cluster 

User interface CAN 

Electronic ignition lock control unit 

Diagnostic CAN 

HERMES control unit

 With a manual or an automatic emergency call, the Service Center can transfer the map data to the vehicle if required. The data is made available to the navigation module of the COMAND controller unit.