Create a Calculation Formula Using the Wizard

About this task

This topic describes how to create a calculation formula using the Insert Function wizard. You can also create a calculation formula using a VBScript code.

Before you begin

  1. Create the tag that you want to use to store the calculation results. You can create the tag manually using Historian Administrator or the Web Admin console. Or, you can copy a tag using Historian Administrator or the Web Admin console.
  2. Access Historian Administrator, select Collectors > Advanced, and then disable the On-line Tag Configuration Changes option. If you do so, each time you update a calculation formula, the collector does not reload tags.

Procedure

  1. In Historian Administrator, select Tags, select the tag for which you want to create a calculation formula, and then select Calculation.
  2. In the Calculation section, remove Null (retain Result =).
    Tip: Avoid selecting other tags until you save your changes or you will lose your code changes.
  3. Select Wizard.
    The Insert Function Wizard window appears.
  4. Under Select Function, select values in the available fields, and then select Insert.
    For information on a list of the available types and associated functions, refer to Types of Functions Supported by the Wizard. For information on each pre-defined function, refer to Built-In Functions. In addition to the built-in functions, you can create your own customized functions.
  5. If you want to perform an unsolicited (also called event-based) calculation, add the trigger tags to the calculation:
    1. In the Calculation Triggers section, select Add.
      The Insert Function Wizard window appears.
    2. Under Select Function, in the Type field, select Add A Calculation Trigger.
    3. Under Tag Browse Criteria, enter the search criteria to find the tag.
      The search results appear in the Browse Results section.
    4. Select the tag that you want to add, and then select Insert.