I’m looking for help understanding why my Cerbo GX (v3.80) does not recognize GNSS data from my Vesper/Garmin Cortex AIS/VHF system on the NMEA 2000 network.
System GPS sources
- Garmin 1223xsv internal GPS
- Vesper/Garmin Cortex GNSS antenna
- Yamaha Helm Master EX GPS antenna
All three are on the same NMEA 2000 backbone.
Cortex GNSS PGNs (confirmed)
- 129025 – Position Rapid
- 129026 – COG/SOG Rapid
- 129029 – GNSS Position Data Plus heading, depth, and full AIS PGNs.
My Garmin 1223xsv units read Cortex GNSS perfectly (valid fix, satellites, accuracy, position, COG/SOG, AIS targets).
Issue on Cerbo GX
Cerbo GX detects Cortex on VE.Can (“CORTEX [693115] – Online”), but:
- GPS menu does not appear
- No GNSS source selectable
- VRM shows no position
Cortex NMEA 2000 identity
From address‑claim:
- Device Class: AIS / Communications
- Device Function: AIS Position / Safety
- Manufacturer ID: 504
Because Cortex does not identify as Device Class 60 / Function 145, the Cerbo GX ignores its GNSS PGNs.
Questions for Victron engineers & community
- Can Cerbo GX accept GNSS from AIS‑class devices like Cortex?
- Is GNSS filtering strictly tied to Device Class / Device Function?
- Any workaround or future plan to allow Cortex (Manufacturer ID 504) to be recognized as a GNSS source?