Configure retrieval options for a tag

You can configure retrieval options separately for each tag in a trend. Tags can either use the retrieval style specified in the trend options, a different predefined retrieval style, or custom retrieval settings.

Most of the retrieval settings that you configure here only apply if you are retrieving data from a Historian with a version of 9.0 or later.

If you are using an earlier Historian version, see Configure other options and Work with retrieval styles for details.

To configure retrieval options for a tag

1. In the Tag List pane, do one of the following:

   • Right-click on the name of the tag and then click Configure.

   • Double-click on the name of the tag.

     The <ServerName:Tagname> dialog box appears with the General tab selected.

2. Click the Retrieval tab.

3. Do one of the following:

   • To have the tag use the same retrieval settings as specified in the trend options, click Style selected at option level in the Retrieval style list. This is the default setting when you add a tag to a trend.

   • To use a predefined retrieval style, click its name in the Retrieval style list. For more information on retrieval styles, see Work with retrieval styles.

   • To use custom retrieval settings, click Custom style in the Retrieval style list.

     

4. Specify any additional settings required.

   • If you are using custom retrieval settings, select a retrieval mode and specify all the settings that are relevant to it.

   • If you are using one of the predefined styles, you can edit all settings that are not covered by the style definition. For information on which settings are covered by style definitions, see Work with retrieval styles. Because a style definition can contain multiple sets of retrieval settings with different retrieval modes, some of the settings available for editing here may turn out to be irrelevant for the retrieval mode that actually gets used for a given query. However, because there is no way to know in advance which retrieval mode will be used, the settings are still available for editing.

     For more information on the various retrieval options, see Understand retrieval options.

5. Specify any additional settings required on the Other tab.

   

   1. In the History version area, click Latest or Original to overwrite the values of a stored tag. For more information on History version, see History Version (wwVersion).

   2. In the Rules area, do the following:

      • In the Timestamp list, click the required timestamp value. For more information on the Time stamp rule, see Timestamp Rule (wwTimestampRule).

      • In the Values to include in calculations list, click the data values that you want to include in the result. You can include the following quality rules:

        Good and uncertain quality: To include data values with uncertain quality in calculations.

        Good quality: To exclude data values with uncertain quality from calculations.

        Optimistic quality: To use the optimistic quality when the data values are missing. This option can be configured at either the tag level or the application level.

        Server default: To use the default quality rule specified at the Historian level.

        For more information on each option, see Quality Rule (wwQualityRule).

   3. In the State retrieval area, do the following:

      • In the State calculation list, click the state calculation.

      • In the State box, specify the value of the state. For example, you can specify either a open or close state for the SteamValve tag.

        Note: The state calculation settings are applicable only to ValueState and RoundTrip retrieval modes.

        For more information on State calculation, see State Calculation (wwStateCalc).

   4. In the Transformation list, click the transformations to be applied to the result. You can include the following transformations:

      • No Transformation: If the query does not specify the filter element or if the value is not overridden for the filter element.

      • Remove outliers: To remove outliers from a set of analog points.

      • Convert analog values to discrete: To convert value streams for any analog tag to discrete value streams.

      • Snap to base value: To force values in a well-defined range around one or more base values to "snap to" that base value. For more information on Transformation, see Analog Value Filtering (wwFilter).