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Creating an Indicator State Calculation Record

Indicator state calculations compute the state of the indicator when a reading is taken. Once defined, these calculations can be reused for other indicators.

Calculations can be simple or complex. Each calculation can be composed of multiple calculation variables.

This topic describes how to create an indicator state calculation record.

To Create an Indicator State Calculation Record

1.	Open the numeric indicator for which you want to assign a state calculation.

2.	In the Properties view, select the States and Alarms tab, and ensure that both This indicator has states and alarms and Calculate the current state using the following calculation are selected.

Tip: APM Administrators can also create calculations from the Enterprise window, Customization Center view, Calculation tabs.

Note: The Calculate option is not available when Track and acknowledge alarms by measurement point is selected. Measurement point readings must be aggregated to use calculations.

3.	Click New. The Calculation window appears.

4.	In the Calculation view, General tab, enter the following information:

Setting Name

Description

Name	Enter a descriptive name for the calculation. If left blank, an error message will appear.

Activation Status

When a calculation is created, its status is automatically set to “Inactive” to prevent it from being used before it is complete or tested. After you have defined a calculation and tested it, you must manually activate it before it can be used.

5.	Select the Calculation tab.

6.	Select the type of expression. A calculation can be based on:

•	VB.NET – Inputs and functions defined on the Calculation tab can be used to create a formula that is calculated at run time. This is the default option

•	C# – Inputs and functions defined on the Calculation tab can be used to create a formula that is calculated at run time

•	Stored procedure – The expression is provided in a stored procedure that receives its inputs at runtime and returns a value

7.	For VB.NET and C# expressions, you must also select the expression type. Your options are “Simple expression” (for single-line commands) or “Complete class” for more complex scripts.

With the Complete class option, a starter script template is provided automatically, which you can edit as needed. You can also click Regenerate from Template to reset the formula to the starter script.

The template scripts include DebugData statements that you can augment to output trace messages when the Check (Test) or Check (Live) method is invoked to test the calculation.

Tip: You can view the template scripts by opening the Enterprise window, clicking the Administration menu and then Calculation options. For more information, see Defining Calculation Options.

8.	If the type of expression is VB.NET, C#, or VB script, in the text box provided, type in the mathematical formula or function that the reading will use.

If you are entering a function, see Using Logical Operators in Calculations.

If you are using a formula, you can use three elements:

•

Calculation indicators (a name that represents data from another asset input): enter a variable name for each input that you want to use in the calculation. Each calculation variable must begin with a letter, cannot contain a period (.), must not exceed 20 characters, and must be unique within the calculation. For example, for an age variable, you might enter “Age1”. You will link a source to the variable in the next step. For more information about asset health calculation variables, see Creating Calculation Variables.

•	Operators (such as, add or multiply): Type the operator in the format shown in Using Logical Operators in Calculations.

•	Constants (that is, a fixed value used in the calculation): enter the value of the constant in the calculation. For example, to divide by two, you would enter “2”.

Example:

To enter a calculation that takes the average of two inputs, you would type:

(Input1 + Input2) / 2

The variables “Input1” and “Input2” are placeholders for data. When the calculation is evaluated, APM gets the current values of the inputs.

9.	Select the Description tab to enter a description about the calculation.

10.	When you are finished, closed the Calculation window.