Configure pens for historical sources and tags

When you start the Trend Client at run time with historical data and then plotting real-time data, you can configure a pen to initialize with a specific historical source and tag. For example, MyEngine.Engine.Historian.Connection is a common relative reference expression for the historical source on a template and, for a pen expression of Me.PV, Me.TagName.PV is a common relative reference expression for the historical tag.

If the historical tagname needs to use relative references, construct the string expression for the historical tagname that evaluates the relative part of the name and append a static part. For example, to reference a UDA named PV, use Me.Tagname+".PV" or a similar expression. You can define this expression on a symbol in a $Reactor template. There are instances of Historian tagnames are Reactor1.PV and Reactor2.PV. If you use the expression in the form Me.PV, it resolves to the current value instead of the tagname. For example, if PV is associated with a temperature, Me.PV would return a temperature rather than the string for the tagname.

You can also use valid relative references such as Me, MyContainer, MyArea, MyEngine, and MyPlatform when configuring the historical tag-names as relative references. For example, to reference the UDA named "Level" in a user-defined object named $Reactor, you can configure the historical tagname as an expression: Me.TagName+".Level". At run time, when the object "Reactor_001" is viewed, the expression is resolved to "Reactor_001.Level" as the historical tag name.

To configure a pen for a historical source and tag

1. Select the pen you want to configure.

2. In the Historical area, configure the source and tag for the pen.

Note: To use the reference mode, you must have already configured a historical data source for the Trend Client. For more information, see "Configure Historical Sources".