HERMES Control Unit, Component Description - GF82.85-P-0221RDM
Model 172.4
with code 360 (HERMES UMTS)
Model 172.4
with code 362 (HERMES communications module LTE)
Location
The HERMES control unit is located behind the front seats on the major assembly carrier.
Tasks
The HERMES control unit is responsible for the following tasks:
- Self-diagnosis for circuit 15 ON, secures operational readiness of emergency call system by checking the following facts:
- Reception of cyclic readiness signal from Supplemental Restraint System (SRS) control unit (N2/10)
- Connection for muting audio sources (mute function)
- Connection to inside rear-view mirror microphone (A67b1) via the audio equipment
- Connection to multifunction antenna (A28/11) (with code 362 (HERMES LTE) or with code 386 (Convenience Telephony)) or to GPS antenna (A2/23) (except code 362 (HERMES LTE) and except code 386 (Convenience Telephony))
- Connection to emergency call system antenna (A2/52)
- Reception of crash signals from the supplemental restraint system control unit (trigger signal for automatic emergency call)
- Set-up of voice or data connections to service provider
- For voice connections:
- Sending of mute signal (mute function) to audio sources
- Reception of signals from the inside rear-view mirror microphone by the audio equipment
- Output of audio signals to the center instrument panel speaker (H4/27) or to the emergency call speaker (H4/48) (except code 810 (Sound system))
- Reception of global positioning system (GPS) signals for position finding (with code 505 (Radio 20 NTG5 without navigation capability))
- Reception of position data from the audio equipment for position finding (with code 367 (Live Traffic Information))
- Forwarding of real-time traffic data from the service provider to the audio equipment (with code 367 (Live Traffic Information))
- Communication of internet signals to the audio equipment (with code 494 (USA version))
- CAN communication via diagnostic CAN (CAN D)
The HERMES control unit receives, e.g. the following signals over the diagnostics CAN:
- Circuit 15 status from electronic ignition lock control unit (N73)
- Readiness signal from Supplemental Restraint System control unit
- Crash information from Supplemental Restraint System control unit (redundant)
- Status of emergency call system button (S93/3s2) from the SAM control unit with fuse and relay module at front (N10/1)
- Status of breakdown assistance button (S93/3s4) and status of MB Info button (S93/3s5) from front SAM control unit (with code 494 (USA version))
- Operation signals from control elements on multifunction steering wheel (e.g. volume control, mute function, set-up or interrupt connection)
- Position data from audio equipment for position finding (with code 522 (Audio 20 radio) or with code 531 (COMAND APS))
- Steering wheel angle from steering column tube module control unit (N80) for position finding (with code 505 (Radio 20 NTG5 no navigation capability))
- Wheel speed signals, yaw rate signals from ESP® control unit (N30/4) for position finding (with code 505 (Radio 20 NTG5 no navigation capability))
The HERMES control unit sends, e.g. the following signals over the diagnostics CAN:
- Request for status "Display" via the anti-theft alarm system/emergency call system button group (S93/3) to the front SAM control unit
- Check signal for the emergency call system self-test
- Map data and miscellaneous data transmitted by the Service Center ("Remote Information Feed") to the audio equipment (with code 494 (USA version))
- Status signals to the instrument cluster
- Display messages for display on Audio/COMAND display (A40/8) to the audio equipment
HERMES stands for: Hardware for Enhanced Remote, Mobility & Emergency Services.
The HERMES control unit calculates the vehicle position and if necessary, it sends a message to the service center.
The HERMES control unit is prepared to send and receive for a period of 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.
Structure
The HERMES control unit contains the following components:
- Internet-compatible communication module with Bluetooth® interface and radio interface for WLAN
- Position finding module
- 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 navigation and other data that is transmitted to the vehicle
| Wiring diagram of HERMES control unit | N112/9 | PE82.85-P-2107-97TAA |