Rockwell Automation FactoryTalk Metrics User Guide - Manual (Page 61)

Collecting Performance Data Chapter 3
Under Formula Part Operator, the Starting Value operator
is preselected, since it is the first value in the arithmetic
formula.
2. Under Formula Part Data Point, click Select.
The Select Data Point dialog box appears.
3. Under Data Points, double-click the data point that you want
to evaluate in the formula.
4. Click Close, and then click Next.
The formula part that you have just created is displayed under
Formula Text and Formula Parts.
5. Repeat steps 1-4 to create another formula part.
You can add values to or subtracts values from the starting
values.
Rockwell Automation Publication PLTMT-UM001M-EN-P-June 2014 61