Returning time between value changes

You can return the amount of time before a tag's value changed to a subsequent value. This time is returned using the wwResolution column.

This functionality works with the cyclic, delta, and full retrieval modes. The delta and full mode behavior of wwResolution does not apply to the AnalogSummaryHistory and StateSummaryHistory tables.

If the time change value is greater than 2,147,000,000 milliseconds (~25 days), then the value of wwResolution column is -1.

• Example 1: cyclic retrieval

• Example 2: delta and full retrieval

• Example 3: querying the widehistory table

• Example 4: querying the history table with the wwvalueselector parameter

• Example 5: calculating total time between value changes