Emergency call system, function

P82.95-3149-79

Function requirements, emergency call system, general

 Circuit 30

 Transport mode not active

 A mobile phone or a telephone module with Bluetooth® (SAP) (with code 379 (Telephone module with Bluetooth® (SAP))) is connected via Bluetooth® to the COMAND controller unit

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. If necessary, the Mercedes-Benz Service Center notifies the local rescue services.

If the COMAND controller unit receives the "Circuit 15R" message from the electronic ignition lock control unit via the interior CAN, the COMAND controller unit checks the operational readiness of the emergency call system. The following checks are carried out:

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

 Availability of a mobile phone that is connected to the COMAND controller unit via Bluetooth®

After a successful check, the emergency call system is operational and "SOS ready" appears in the telephone menu on the Audio/COMAND display.

 In the event of a fault, depending on the fault type a fault message appears on the Audio/COMAND display and is stored in the fault memory of the COMAND controller unit.

The emergency call system function comprises the following subfunctions:

 Emergency call system status indication

 Voice connection between vehicle and Mercedes-Benz Service Center

 Data from the Supplemental Restraint System control unit

 Manual or automatic emergency call

 An automatically triggered emergency call has priority via a manually triggered emergency call.

Emergency call system status indication

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 ready for operation ("SOS ready" in the telephone menu)

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

 Fault in emergency call system

The COMAND controller unit sends the display messages via a low voltage differential signaling (LVDS) line to the Audio/COMAND display.

Additional function requirements for voice connection between vehicle and Mercedes-Benz Service Center

 Manual or automatic emergency call triggered.

Voice connection between vehicle and Mercedes-Benz Service Center

Once the emergency call has been triggered, a voice connection with the Mercedes-Benz Service Center is established. The COMAND controller unit mutes the audio sources and interrupts any telephone call that may be in progress. 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. If possible, the Mercedes-Benz Service Center carries out the call in the language that was selected in the system settings of the COMAND controller unit and transmitted in the data telegram. The inside rearview mirror microphone is used for voice commands; it is integrated into the inside rearview mirror (A67). The signals from the hands-free system microphone are transmitted to the COMAND controller unit via a direct line.

The COMAND controller unit sends the signals of the hands-free system microphone to one of the following components via the Bluetooth® antenna:

 Mobile phone (up to 31.05.2013 except code 386 (Comfort telephony), as of 01.06.2013 except code 379 (Telephone module with Bluetooth® (SAP)))

 Bluetooth® module (up to 31.05.2013 with code 386 (Comfort telephony))

 Telephone module with Bluetooth® (SAP profile) (with CODE 379 (Telephone module with Bluetooth® (SAP profile)))

On vehicles with CODE 386 (Comfort telephony) as of 01.06.2013, the mobile phone sends the signals to the Mercedes-Benz service center via the following route:

Mobile phone contact plate 

Cellular telephone system antenna amplifier/compensator 

Multifunction antenna

On vehicles with CODE 386 (Comfort telephony) up to 31.05.2013, the Bluetooth® module sends the signals to the Mercedes-Benz service center via the following route:

Cellular telephone system antenna amplifier/compensator 

Multifunction antenna

On vehicles with code 379 (Telephone module with Bluetooth® (SAP)), the telephone module with Bluetooth® (SAP) sends the signals as follows to the Mercedes-Benz Service Center:

Mobile phone contact plate (as of 01.06.2013) or Bluetooth® module (up to 31.05.2013) 

Cellular telephone system antenna amplifier/compensator 

Multifunction antenna

 The telephone signals are received via the reverse route.

On vehicles with CODE 810 (Sound system), the COMAND controller unit forwards received signals via MOST to the sound system amplifier control unit for the voice output.

On vehicles except code 810 (Sound system), the COMAND controller unit outputs the received signals over the speaker system.

In a normal case, the voice connection is terminated by the Mercedes-Benz Service Center or the user.

 The setup of a voice connection to the Mercedes-Benz Service Center is aborted after several unsuccessful dialing attempts, and an appropriate message appears on the Audio/COMAND display.

 Model 172.4
up to model year 2017
with code 347 (Mercedes-Benz emergency call system)
with code 386 (Comfort telephony)
except code 379 (Telephone module with Bluetooth® (SAP profile))
The antenna of the mobile phone is used if the multifunction antenna fails.

Additional function requirements for data from supplemental restraint system control unit

 Circuit 15R ON

Data from the Supplemental Restraint System control unit

In the event of an accident with airbag deployment, an emergency call is automatically sent out immediately. An emergency call is sent out regardless of the severity of the accident. The supplemental restraint system control unit sends the crash information, including the crash level as follows:

Chassis CAN 

Front SAM control unit with fuse and relay module 

Interior CAN 

COMAND control unit

 The supplemental restraint system control unit transmits a readiness signal cyclically via the same route (e.g. every 500 ms). In this way the COMAND controller unit monitors the communication with the supplemental restraint system control unit and the correct operation of the crash detection.

Manual or automatic emergency call

In an emergency situation, a service receptionist from the Mercedes-Benz Service Center can obtain an overview of the status inside the vehicle with the aid of the data received from the emergency call system 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 manual or automatic emergency call function consists of the following subfunctions:

 Function sequence for activating an automatic emergency call

 Function sequence for activating a manual emergency call

 Function sequence for transmitting the data telegram and communicating with the Mercedes-Benz Service Center

 Function sequence for ending the emergency call by the user

Function sequence for activating an automatic emergency call

In the event of an accident with airbag deployment, an emergency call is automatically sent out immediately. An emergency call is sent out regardless of the severity of the accident. The supplemental restraint system control unit sends the crash information, including the crash level as follows:

Chassis CAN 

Front SAM control unit with fuse and relay module 

Interior CAN 

COMAND control unit

An automatic emergency call is also triggered (redundant) if the COMAND controller unit receives the "central locking emergency opening" signal and the cyclic readiness signal ("sign of life") from the supplemental restraint system control unit is not received.

 The supplemental restraint system control unit transmits a readiness signal cyclically via the same route (e.g. every 500 ms). In this way the COMAND controller unit monitors the communication with the supplemental restraint system control unit and the correct operation of the crash detection.

The "Central locking emergency opening" signal is received by the COMAND controller unit via the interior CAN from the front SAM control unit with fuse and relay module.

Additional function requirements for triggering a manual emergency call

 No automatic emergency call is active.

Function sequence for activating a manual emergency call

A manual emergency call can be dialed using the address book entry. The address book of the COMAND controller unit can be opened in the Telephone menu. The emergency call address book entry ("Mercedes-Benz Emergency Call") is in first position.

The reserved entry in the address book is selected using one of the operating facilities:

 Telephone buttons or keypad on the audio equipment

 Audio/COMAND control panel

 Multifunction steering wheel button groups

 Voice control system

The control signals from the telephone buttons or the keypad on the COMAND controller unit are processed internally.

The control signals from the Audio/COMAND control panel are forwarded via telematics CAN to the COMAND controller unit.

The steering wheel electronics forward the control signals of the multifunction steering wheel button groups via the following path:

Steering LIN 

Steering column tube module control unit 

Chassis CAN 

Instrument cluster 

Interior CAN 

COMAND control unit

With the voice control system, the inside rearview mirror microphone records the voice commands and forwards them via a direct line to the COMAND controller unit.

Function sequence for transmitting the data telegram and communicating with the Mercedes-Benz Service Center

Once a manual or automatic emergency call has been triggered, the COMAND controller unit sets up a voice connection with the Mercedes-Benz Service Center. Audio sources are muted, and existing telephone connections are interrupted. The status of the connection setup is indicated by the following messages on the Audio/COMAND display:

 "Activating" (setting up the call)

 "Transmitting data" (transmission of emergency call data (data telegram))

 "Connected" (voice connection established)

As soon as a connection to the mobile phone and the mobile telephone network has been established, the COMAND controller unit automatically transmits two text messages using Message Access Profile (MAP) to the Mercedes-Benz Service Center. The text messages contain the following information:

 Time stamp

 GPS (global navigation system) position of the vehicle

 Language

 Vehicle identification number

 MB Contact status (ON or OFF)

Once the text messages have been transmitted, the voice connection is set up. The COMAND controller unit first transmits a shortened data telegram using the dual tone multiple frequency (DTMF) procedure via the voice connection. Then the user is contacted by a service receptionist from the Mercedes-Benz Service Center.

Function sequence for ending the emergency call by the user

The user can terminate the emergency call by pressing the "END" button on the COMAND controller unit or the accept/terminate phone call button in the relevant sub-field.

 During an automatic emergency call the "END" button and the accept/terminate phone call button are temporarily disabled while the connection is being set up in order to avoid unintentional termination. Pressing the "END" button or the Accept/terminate phone call button 2 times briefly in succession can interrupt the automatic emergency call.

The control signals from the telephone buttons or the keypad on the COMAND controller unit are processed internally.

The control signals of the accept/terminate phone call button are forwarded by the steering wheel electronics via the following route:

Steering LIN 

Steering column tube module control unit 

Chassis CAN 

Instrument cluster 

Interior CAN 

COMAND control unit

Prioritization

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.