Configure formula data references

The formula data reference does not support strings or other non-numeric value types.

Create formula data references to perform custom calculations.

1. Choose one of the following actions.

   • In the Elements browser, select the desired element.

   • In an element template, select the desired element template in the Library browser.

2. In the Attribute or Attribute Templates tab, select the attribute.

3. From the Data Reference drop-down list, choose Formula.

4. Click the Settings button to open the Formula Data Reference configuration window.

5. If your equation requires an attribute value, click to add it as a parameter (Define parameters for formula data references).

6. Select the Default Values Allowed check box to enable PI AF to use attribute default values in the calculation. Default values are specified on the attribute template. If you clear the check box, the calculation fails when the data for one or more attributes is not available.

7. Click to begin defining the equation. For more information, see Define equations for formula data references.

8. In the Unit of Measure field, specify the unit of measure the result of the formula or calculation sequence will produce, as described in Units of measure in formula data references.

9. In the Minimum field, enter an appropriate value for the minimum returned value. If the calculated value is less than this minimum, the data reference returns the minimum value you specify. If there is no minimum value for this calculation, leave the Minimum box blank.

10. In the Maximum field, enter an appropriate value for the maximum returned value. If the calculated value is greater than this maximum, the data reference returns the maximum value you specify. If there is no maximum value for this calculation, leave the Maximum box blank.

    Note: Select the Stepped check box for the value to be stepped when plotted.

11. Click Evaluate to test the data reference. The value returned by the calculation sequence appears in the adjacent box. When the formula data reference is configured under a template attribute, the calculation uses the default values for the template attributes. When the configuration is done under an element attribute the actual data is used for the calculation.

12. Click OK.

13. Configure the rest of the attribute settings as you would for any other attribute.