Quality rule - query 6

For RoundTrip, StateSummary, and ValueState modes, the OPC qualities are only combined with the same state in a cycle. If the state only occurs once in a cycle, then the qualities of that state will be returned. The returned NULL state will always have an OPC quality of 0 and Quality Detail of 65536. The same qualities are returned for a state that has no roundtrip in RoundTrip mode.

SELECT TagName, DateTime, Value, QualityDetail, OPCQuality, StateTime

FROM History

WHERE TagName = 'I001'

AND DateTime >= '2009-09-12 00:20'

AND DateTime <= '2009-09-12 00:40'

AND wwResolution = 10000

AND wwRetrievalMode = 'RoundTrip'

AND wwStateCalc = 'MaxContained'

If you run this query against the following sample data:

The results are: