Issue
A Niagara R2 UNC has been operating for more than two years communicating with ASD devices. Recently, the station stopped polling them without any external influence. The ASD devices remain online and operational but the UNC station stopped polling them. A reboot of the UNC resolved the issue. What caused it?
Environment
Niagara R2 UNC-520, version 522 or older
Cause
An issue related to a timer rollover event caused the UNC system time to stop updating if the UNC has not had a reboot in 2.26 years.
This, in turn, stopped the ASD driver from polling since it relies upon the system clock.
This issue affects other drivers as well.
Resolution
The short-term solution is to reboot the UNC before 2.26 years (or 828 days).
The ideal solution is to upgrade to version r2.301.529. The polling issue was fixed in this version.