HERMES Control Unit, Component Description - GF82.85-P-0221FR
Model 257, 290
up to model year 2021
with code 362 (HERMES communications module LTE)
Shown on model 257.3
Location
The HERMES control unit is located in the rear center instrument panel behind the upper control panel control unit (N72/1) and above the head unit (A26/17).
Tasks
The HERMES control unit controls communication between the vehicle and the service provider or user, and therefore make it possible to use numerous vehicle-related services.
"HERMES" stands for: "Hardware for Enhanced Remote, Mobility & Emergency Services".
2 antenna connections are used for communication in order to achieve transmission and reception diversity.
The HERMES control unit has the following individual tasks:
- Reception of power supply via circuit 30t and circuit 31 (input)
- Self-test, ensuring that the emergency call system is functional by checking the following:
- Reception of cyclic readiness signal ("Sign of life") from the Supplemental Restraint System control unit (N2/10) over the seat occupancy LIN (LIN E2)
- Connection for muting audio sources (mute function)
- Connection to driver hands-free system microphone (B25/20), through head unit
- Connection to emergency call system antenna 1 (A2/140) (model 257) or to the telephone antenna splitter (A2/109), the left telephone antenna (A2/102) and the right telephone antenna (A2/103) (model 290)
- Connection to emergency call system antenna 2 (A2/141)
- Reception of crash signals over the seat occupancy LIN from the Supplemental Restraint System control unit (and redundantly over the diagnostics CAN (CAN D))
- As of 01.06.2019 or with code 506 (Radio Audio 20 NTG 5.5) except code 355 (Pre-installation for navigation retrofit) up to 31.05.2019: Reception of GPS signals (Global navigation system) for position finding via the GPS antenna (A2/23) (Input)
- Establishing voice or data links via the emergency call system antenna 1 (model 257), via the telephone antenna splitter, left telephone antenna and right telephone antenna (model 290) or via the emergency call system antenna 2 (Input and output)
- As of 01.06.2019 with code 355 (Pre-installation for navigation retrofit) or with code 531 (COMAND APS): Forwarding GPS signals to head unit (Output)
- With voice connections: Transmitting of the mute function signal to following components (output):
- Head unit (model 257 (except 257.361) except code 810 (Sound system) and except code 811 (Advanced Sound System))
- Midline sound system amplifier control unit (N40/2) (model 257.361, model 290 except code 810 (Sound system) and except code 811 (Advanced Sound System))
- Sound system amplifier control unit (N40/3) (with code 810 (Sound system))
- Advanced sound system amplifier control unit (N40/7) (with CODE 811 (Advanced sound system))
- For voice connections: Reception of signals from driver hands-free system microphone via head unit (input)
- With voice connections: Transmitting of the audio signals to the following components (output):
- Center instrument panel midrange speaker (H4/78) (with code 811 (Advanced sound system))
- Center instrument panel speaker (H4/27) (except code 811 (Advanced sound system))
- With code 367 (Live Traffic Information): Forwarding of real-time traffic data over the integrated radio interface and the WLAN antenna (A2/83) to the head unit and reception of position data from the head unit (radio interface)
- With code 531 (COMAND APS) or code 506 (Audio 20 radio NTG 5.5): Communication of Internet signals over the radio interface and the WLAN antenna to the head unit (radio interface)
- CAN communication via the diagnostic CAN with the electronic ignition lock control unit (N73) (CAN interface)
The HERMES control unit can receive, e.g. the following CAN signals over the electronic ignition lock control unit:
- Status of "Circuit 15R" from the electronic ignition lock control unit (trigger signal for the self-test of the emergency call system)
- Crash signal from the Supplemental Restraint System control unit (redundant) (automatic emergency call)
- Request to trigger automatic emergency call from Mercedes-Benz Intelligent Drive control unit (N62/4) (with code 23P (Driving Assistance Package) or code P20 (Driving Assistance Plus Package)), if the Active Emergency Stop Assist brakes the vehicle until it comes to a standstill
- Control signal from SOS button (N70s11) from overhead control panel control unit (N70) (manual emergency call)
- Operation signal of Mercedes me connect button (N70s16) from overhead control panel control unit (telematics services)
- Control signals of head unit multifunction steering wheel button group (S163/2) from steering column tube module control unit (N80) (volume control, disconnect connection)
- Signals of the steering wheel angle sensor (N49) from the steering column tube module (MRM) control unit (position finding)
- Wheel speed signals, yaw rate signals from the Electronic Stability Program control unit (N30/4) (position finding)
- Position data from the head unit (position finding)
The HERMES control unit can transmit the following CAN signals, for example:
- Actuation of light-emitting diodes in the following buttons via the electronic ignition lock control unit to the overhead control panel control unit (status indication):
- SOS button
- Mercedes me connect button
- Map data and miscellaneous data transmitted from the Service Center ("Remote Information Feed") via the electronic ignition lock control unit to the head unit (telematics services)
- Status signals via the electronic ignition lock control unit to the instrument cluster
- Display messages for showing on Audio/COMAND display (A40/8), over the electronic ignition lock control unit and the head unit
- Request of data or actions for telematics services via the electronic ignition lock control unit to the control units involved
The HERMES control unit is ready for reception and transmission for 30 days: As soon as an SMS is received, the HERMES control unit is also activated (wake-up); after 30 days, the emergency call system goes into "sleep mode". Following circuit 15 ON a self-test is performed.
Structure
- Integrated Internet-compatible communications module with Bluetooth® interface and radio interface for wireless local area network (WLAN)
- Integrated locating module
- Integrated GPS receiver for position finding (date, time, history and last-known location) for the listed vehicle-related services
- Memory for vehicle-specific data
- Buffer for map and other data that is transmitted to the vehicle
| Wiring diagram of HERMES control unit | PE82.85-P-2107-97XBA |