Create an expression analysis template

In PI System Explorer, you can create an expression analysis template for an element template. In the template, you can create an expression for each calculation. To record the value that an expression calculates, map the output to an attribute template. You can create new attribute templates from the expression-analysis template.

1. In the navigator, click Library.

2. In the Library browser, select the element template where you want to create the analysis template.

3. In the viewer, click the Analysis Templates tab.

   The tab lists any analysis templates already defined for the element template.

4. Create a new analysis template for the element template:

   • If no analysis templates exist, click Create a new analysis template to create the first one.

   • Otherwise, click New Analysis Template to create a new one.

5. Enter information to identify the analysis:

   • Name

     The name that uniquely identifies this analysis.

   • Description

     Optional text that describes the analysis.

   • Categories

     Optional category that you can assign to the analysis. Click the list and select the check box next to categories you want to assign or click New to create a new category.

   • Analysis Type

     Click Expression.

6. Optional. Clear the Enable analyses when created from template check box so that the analysis is created in Disabled status.

   By default, a new analysis will be created with Enabled status. You must clear the option if you do not want to start the analysis when created.

7. Optional. To temporarily evaluate expressions in the analysis template based on values of a particular element, click the Select an example element link and select an element based on the current element template.

   If no elements have been created from the current element template, you must create an element first.

   Templates have no concrete data associated with their attributes. You cannot evaluate an expression in an analysis template, unless you borrow attribute values from a specific element.

   PI System Explorer sets Example Element to the element you selected.

8. Specify one or more expressions for the analysis.

   Enter each expression in a row. An expression specifies inputs and calculations. See Understand expression analyses.

9. Map at least one expression to an output attribute template.

   1. In the Output Attribute column for the expression, click Map.

   2. Specify the attribute template.

   To ...	Do this ...
   Map the output to an existing attribute template	Click the name of the attribute template. Select an attribute template with a PI point data reference to store the history of the calculation. For best performance when you do not require history, use an attribute template with an analysis data reference.
   Map the output to a new attribute template	Click New Attribute Template to open the Attribute Template Properties window. Indicate whether the attribute should save the history of the output: Click Yes to create an attribute with a PI point data reference. This attribute saves the history of the output. Click No to create an attribute with an analysis data reference. This attribute calculates a new value when requested. Configure the attribute template to create: Name Name of created attribute. Description Optional text that describes the attribute. Data Server For attributes that save output history, the Data Archive server that stores the PI point data reference. By default, this is set to %Server%, which sets to the default Data Archive server. Value Type The data type the attribute stores. After creating the attribute template, you can refine its definition from the Attribute Templates tab. Click OK to create the attribute template.

10. Optional. If you specified an example element, click Evaluate to verify that output values of individual expressions.

    Specify scheduling for the analysis. See Understand analysis scheduling.

11. Optional. If you specified an example element, verify the analysis by reviewing the results produced with historical data:

    1. In the analysis list, right-click the analysis and then click Preview Results.

    2. Enter a start time and end time not later than the current time, and click Generate Results to see a list of results.

12. To apply changes and save your work locally, click on the toolbar.

13. Click Check In on the toolbar to save the analysis template to the PI AF server and to create the analysis for any element based on the element template.