Niagara R2 UNC Station Fails to Start LonWorks Driver – Communication Lost to LON Controllers

[Product_Support]

Issue

After restarting a Niagara R2 UNC station, communication to LON controllers is lost. The station fails to open the LonWorks driver and cannot start LON communications. Errors such as the following appear in the standard output window:

Error opening driver LON1 java.lang.Exception: Unable to open lonworks driver
Cannot startService [Sys: LonWorksService]
java.lang.IllegalStateException: Unable to open lonworks driver

Additional LonException codes like ldvWrite() failed - rc = 6 may follow.

Product Line

TAC IA Series

Environment

• Niagara R2 UNC-520-2
• Niagara R2 UNC-410-1
• Also applies to obsolete models:  UNC-500, UNC-510, UNC-600, UNC-610

Cause

The Niagara operating system is unable to communicate with the onboard Echelon MIP chip.

Resolution

To confirm the issue:

1. Open the running station in Tree View.
2. Navigate to localLonDevice → Properties → Engineering tab.
3. Blank out the neuronId and click Apply.
4. Reboot the UNC.
5. If the neuronId field shows all zeros after reboot, the MIP chip has failed.

This issue is not field-repairable.