Retrieval tab options

Use the Retrieval tab to specify the "granularity" of the data to be returned.

To configure retrieval mode options

1. In the Retrieval mode list, select the retrieval mode that allows you to access the data stored in a AVEVA Historian in different ways.

2. In the Main options area, do the following:

   • Cyclic: Cyclic based retrieval is the retrieval of stored data for the given time period based on a specified cyclic retrieval resolution, regardless of whether or not the value of the tag(s) has changed.

   • Full: Full retrieval mode returns one row per stored value for tags at a given time interval, including duplicate values with different timestamps. You can use full retrieval for all tag types.

3. In the Query row limit list, select the maximum number of rows for the data retrieval to avoid excessively large result sets. For example, if you set a row limit of 200, the historian only returns the first 200 rows of a query’s results. The row limit applies to each query.

4. If you select cyclic retrieval mode, configure additional options in the Cyclic attributes area.

   • XX values over equal time intervals: The number of rows to be returned for a specified time period. For cyclic retrieval, the rows are spaced evenly across the time period, and the default row count is 100 rows. For cyclic retrieval, the row count is applied for each tag in a query.

   • Values spaced every XX ms: The sampling rate, in milliseconds, for retrieving the data in cyclic mode.

   • Interpolation type: The interpolation type for data retrieval.

5. If you select delta retrieval mode, configure additional options in the Delta retrieval deadbands area.

   • Time: The minimum time, in milliseconds, between returned values for a single tag. Applies only to delta retrieval.

   • Value: The percentage of full scale (range), in engineering units. Any value changes that are less than this percentage will not be returned. Applies only to delta retrieval. The default is 0.

For more information on configuring the other data retrieval options, see Other Tab.