HERMES Control Unit, Component Description - GF82.85-P-0221GW

Model 463 

as of model year 2017 up to model year 2019 

with code EK1 (HERMES communications module LTE) 

Model 463 

as of model year 2017 up to model year 2019 

with code EM2 (Communications module (UMTS) for the use of Merced) 

Shown on model 463, left-hand drive vehicle 

Location 

The HERMES control unit is located under the front passenger seat.

Tasks 

The HERMES control unit is responsible for the following tasks:

• Prioritization of the services in the internal arithmetic unit
• Self-test, ensuring that the emergency call system is functional by checking the following:
  • Receipt of cyclic readiness signal ("Sign of life") from the supplemental restraint system control unit (N2/10)
  • Connection for muting audio sources (mute function)
  • Connection to the hands-free system microphone (A67b1), via the COMAND controller unit (A40/3)
  • Connection to the emergency call system antenna 1 (A2/140)
  • Connection to emergency call system antenna 2 (A2/141)
• Reception of crash signals from the supplemental restraint system control unit as trigger signal for the automatic emergency call (input)
• Establishing voice connections or data links to the service provider via the emergency call system antenna 1 and the emergency call system antenna 2 (transmission and reception diversity) (input and output)
• For voice connections: Transmission of a mute signal (mute function) to the sound system amplifier control unit (N40/3) (with code EU9 (Harman Kardon® Logic 7® surround sound system)) or to the COMAND controller unit (except code EU9 (Harman Kardon® Logic 7® surround sound system)) (output)
• With voice connections: reception of signals from the hands-free system microphone via the COMAND controller unit (input)
• With voice connections: transmission of audio signals to the center instrument panel speaker (H4/27) (output)
• Power supply via circuit 30 and circuit 31 (input)
• Forwarding of real-time traffic data from the service provider to the COMAND controller unit and reception of position data from the COMAND controller unit via a USB connection (Universal Serial Bus) (with code EM2 (HERMES - UMTS communications module) and code EM0 (Live Traffic Capability (HERMES))) (input and output)
• Communication of the Internet signals via the radio interface and the WLAN antenna (A2/83) to the COMAND controller unit (with code EK1 (HERMES - LTE communications module)) (radio interface)
• CAN communication over diagnostic CAN (CAN D) with electronic ignition lock control unit (N73) (CAN interface)

The HERMES control unit can receive, e.g. the following CAN signals via the electronic ignition lock control unit:

• Status of circuit 15 from the electronic ignition lock control unit as trigger signal for the emergency call system self-test
• Cyclic readiness signal ("sign of life") from the supplemental restraint system control unit as check signal
• Crash information from the supplemental restraint system control unit (redundant), including crash level
• Control signal of the emergency call system button (S93/3s2) from the SAM control unit (N10) (manual emergency call)
• Control signal from the breakdown assistance button (S93/3s4) and the MB-Info button (S93/3s5) from the SAM control unit (with code EK1 (HERMES - LTE communications module))
• Control signals for the button groups on the multifunction steering wheel from the instrument cluster (A1) (e.g. volume control, mute function, establish or disconnect connection)
• Position data from the COMAND controller unit, for position finding

The HERMES control unit can transmit the following CAN signals, for example:

• Status indications by actuating LEDs in the anti-theft alarm system/emergency call system button group (S93/3) via the electronic ignition lock control unit to the SAM control unit (for status indication)
• Check signal for anti-theft alarm system/emergency call system button group via the electronic ignition lock control unit to the SAM control unit (for the self-test of the emergency call system)
• Display messages for showing on the Audio/COMAND display (A40/8), via the electronic ignition lock control unit to COMAND controller unit
• Map data and miscellaneous data sent from the service center ("Remote Information Feed") via the electronic ignition lock control unit to the COMAND controller unit
• Status signals via the electronic ignition lock control unit to the instrument cluster

"HERMES" stands for: "Hardware for Enhanced Remote, Mobility & Emergency Services".

Structure 

The following components are integrated into the HERMES control unit:

• Integrated Internet-compatible communications module with Bluetooth® interface and radio interface for wireless local area network (WLAN)
• A memory for vehicle-specific data
• A buffer for navigation data and other data transferred to the vehicle
• Integrated GPS receiver (nonfunctional)
• Integrated position finding module (nonfunctional)

Function 

The communications module integrated in the HERMES control unit is a cellular telephone system transceiver, which makes voice and data communication with the service center possible via mobile radio frequencies. Other functions of the communications module are:

• Four-day transmission and reception capability: As soon as an SMS is received, the HERMES control unit is also activated (wake-up); after four days, the emergency call system goes into "sleep mode"
• Following circuit 15 ON a self-test is performed

Wiring diagram of HERMES control unit

PE82.85-P-2107-97ZGA