Power SCADA Operation: ‘Error evaluating 450’ is getting logged in Tracelog Alarm log file

Issue
Why this error ‘Error evaluating 450’ from alarm engine is logged against few alarm tags in tracelog file?

Environment
Power SCADA Operation (PSO) 2020
EcoStruxure Power Operation (EPO) 2021

Cause
There could be two causes for this “Error evaluating 450”

1. This error gets logged when the IO Device is not communicating but while startup reading the variable tag values of alarm's VarA / VarB to process the alarm.
2. The linked variable tag for the alarm under Source tab is missing/deleted/wrongly configured.

In "Error evaluating 450" error 450 is the error code which stands for INVALID_TAG_DATA. This occurs when there is an error reading either m_VarA or m_VarB.

Resolution
In order to identify the exact cause for this error in the trace log, set the below citect.ini parameter which enables additional logging in trace log of alarm server in which it will indicate whether the problem is with m_VarA or m_VarB. After setting below ini parameter it is needed to restart the citect processes.

[Debug]SeverityFilter=Warning

Released for: Schneider Electric USA