Connection Troubleshooting
Diagnose the layer that failed: configuration, permissions, connection, protocol/identity, supported data or authorization. Avoid resetting hardware or deleting user settings as a first response.
Triage in order
- Stop/F12 if unintended output or repeated faults are possible.
- Read the selected transport's status, not a stale message from another adapter.
- Open Setup and compare the saved configuration with the actual port/endpoint.
- Use Refresh ports or explicit saved-configuration reconnect where supported.
- Inspect Application Log and Diagnostics for the same operation/time.
- Only then change the specific incorrect setting or seek hardware/administrator help.
| Symptom | Likely checks / recovery |
|---|---|
| No USB adapter in list | Attach correct device, refresh; inspect description/VID:PID; enter a valid manual/stable path if needed |
| Many ttyS entries | Use USB-prioritized list; Show all only when selecting a legitimate non-USB port |
| Missing/disconnected port | Check cable/device and refresh after hot-plug; reselect saved/manual path |
| Permission denied / busy | Close competing process; verify device permissions/group access with administrator; renew login session where required |
| Serial connection succeeds, no CAN data | Check adapter protocol, wiring, CAN bitrate, termination, power and actual bus traffic |
| Network connection denied | Check host/port/interface, allowlist, key/capability and trusted tunnel; do not guess new credentials |
| can0 absent / BUS-OFF | Operating-system/HAT/backbone investigation; do not repeatedly reset the live interface from the app |
| Restart required | Respect native session terminal lifecycle; restart application rather than repeated Start |
Connected is not authorized or decoded
RX-only connection does not permit ordinary TX. Viewer disables instruments. Individual Enable/interval and encoder/mapping support matter after authorization. A raw PGN in Diagnostics is not proof of a corresponding widget or a receiving chartplotter display.
Save transport changes while stopped before using saved-configuration reconnect. Cancelled Setup drafts must not be mistaken for saved settings. After an abort/fault, reconnect explicitly as the interface requires; never let a stale authorization be the recovery plan.
Illustrated controls
Figure 74. Use the device path and description to select the intended serial port. Click to enlarge.
For Linux serial access failures, see Linux Serial Port Permissions.
Related topics
NMEA2000 Overview · NMEA0183 Overview · Network NMEA2000 · SocketCAN · CANable SLCAN · Waveshare USB-CAN-A · Actisense NGT-1 · Signal K · Device Discovery and Diagnostics · Enable, Dispatch and Sending · Route Overview · Engineering Units