How do I troubleshoot PI AF Analysis errors?
How do I troubleshoot PI AF Analysis errors?
PI AF Analysis Service evaluates expressions, rollups, and event frame generation. When analyses fail, here's how to diagnose and fix them.
Common Error Types
"Calc Failed" Status
- The expression itself has an error (division by zero, missing attribute, type mismatch).
- Fix: Open the analysis in PI System Explorer, click Evaluate, and check the error message.
"No Data" or "Pt Created" Values
- Input attributes aren't resolving to valid PI points.
- Fix: Check that data references are correctly configured and the PI points exist.
Analysis Not Evaluating
- The Analysis Service may not be running or may not be managing the element.
- Fix: Check Analysis Service > Management tab — ensure the element's analyses are mapped to your analysis service.
Diagnostic Steps
- PI System Explorer: Right-click the analysis > Evaluate to test the expression.
- Analysis Service logs: Check
%ProgramData%\OSIsoft\PI Analysis Service\Logs\. - Status attribute: If you have a status output, check what value it's writing.
- Backfilling: Use Recalculate to re-run the analysis for a time range.
Expression Tips
' Check for bad data before dividing
If BadVal('Input1') Or BadVal('Input2') Then
NoOutput()
Else
'Input1' / 'Input2'
EndIf
Performance
- Limit the number of analyses per service instance (< 50,000 recommended).
- Use periodic scheduling for non-critical calculations instead of event-triggered.
- Monitor CPU and memory on the analysis service machine.
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