State calculation (wwStateCalc)

The state calculation setting applies to ValueState and RoundTrip retrieval.

For ValueState retrieval, you can choose the type of state calculation (aggregation) to be performed on the data:

• Minimum: The shortest amount of time that the tag has been in each unique state.

• Maximum: The longest amount of time that the tag has been in each unique state.

• Average: The average amount of time that the tag has been in each unique state.

• Total: The total amount of time that the tag has been in each unique state.

• Percent: The total percentage of time that the tag has been in each unique state.

• MinContained: The shortest amount of time each tag has been in each unique state for each cycle, disregarding the occurrences that are not fully contained with the calculation cycle.

• MaxContained: The longest amount of time that the tag has been in each unique state for each cycle, disregarding the occurrences that are not fully contained with the calculation cycle.

• AvgContained: The average amount of time that the tag has been in each unique state for each cycle, disregarding the occurrences that are not fully contained with the calculation cycle.

• TotalContained: The total amount of time that the tag has been in each unique state for each cycle, disregarding the occurrences that are not fully contained with the calculation cycle.

• PercentContained: The percentage of time that the tag has been in each unique state for each cycle, disregarding the occurrences that are not fully contained with the calculation cycle.

All results except Percent are in milliseconds. Percent is a percentage typically between 0.0 and 100.0. The percentage can be higher than 100 in certain circumstances.

The nature of the data and how you set the cycle count determines whether you should use a "contained" version of the aggregation. The calculations apply to each unique value state that the tag was in during each retrieval cycle for the query. The total and percent calculations are always exact, but the minimum, maximum, and average calculations are subject to "arbitrary" cycle boundaries that do not coincide with the value changes. Therefore, non-intuitive results may be returned. This is most apparent for slowly-changing tags queried over long cycles.

For example, a string tag that assumes only two distinct values changing every 10 minutes is queried with a cycle time of two hours. Going into a cycle, the value (state) at the cycle boundary is recorded. If the value then changes a short while into the cycle, the state found at the cycle start time will most likely end up being the minimum value. Likewise, the state at the cycle end time is cut short at the cycle end time. The two cut-off occurrences in turn skew the average calculation.

For RoundTrip retrieval, you can only specify the following types of state calculations (aggregations) to be performed on the data. The calculations are for each unique state within each retrieval cycle for the query.

• MinContained. The shortest time span between consecutive leading edges of any state that occurs multiple times within the cycle, while disregarding state occurrences that are not fully contained inside of the cycle.

• MaxContained. The longest time span between consecutive leading edges of any state that occurs multiple times within the cycle, while disregarding state occurrences that are not fully contained inside of the cycle.

• AvgContained. The average time span between consecutive leading edges of any state that occurs multiple times within the cycle, while disregarding state occurrences that are not fully contained inside of the cycle. (This is the default.)

• TotalContained. The total time span between consecutive leading edges of any state that occurs multiple times within the cycle while disregarding state occurrences that are not fully contained inside of the cycle.

• PercentContained. The percentage of the cycle time spent in time span between consecutive leading edges for a state that occurs multiple times within the cycle while disregarding value occurrences that are not fully contained inside of the cycle.