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Creating a Calculation Record

Asset health calculations are reusable calculations that select assets for reporting and create asset health indexes. These indexes are a numerical score applied to assets representing their viability, and are displayed in asset health reports.
Calculations can be simple or complex. Each calculation can be composed of multiple calculation variables; for example, a simple calculation could determine the age of the asset at the time the reading was taken. Another could determine how many times an asset has received a specific indicator alarm within the past year. Calculations that are executed as part of the asset health report are stored in the asset health report definition.
A maximum of five calculations can be used in each report definition, and each calculation can include multiple variables that support the use of minimum and maximum limits, factor tables, and weighting.
Each calculation can have multiple states that apply descriptive conditions to numeric ranges. This allows each calculation to have its own definition of what is considered good, fair, bad, and so on. The value of the calculation result determines the state of the asset health index. For example, one calculation that results in the range of zero to 10 could be assigned a state of “poor”, and another calculation must have a result of zero to 50 to be considered “poor”.
Calculations can also be assigned to groups and classifications to assist in organizing or arranging the calculations.
You can set the order in which calculations are executed in the report definition. You can also select a primary calculation and use it on asset health sidebar charts.
This topic describes how to create an asset health calculation record and directs you to related topics.

To Create a Calculation Record

1.
On the Site window, select the Asset Health view and then the Calculations tab. By default, this tab lists all asset health report calculations for this site and above.
Tip: You can also create calculations from the Asset Health Report Definition window, General tab.
2.
Click New. The Asset Health Calculation window appears.
3.
On the Properties 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.
Owner
The originator of the calculation. The value is pre-populated with either APM (APM-supplied calculations) or Customer (user-defined).
Type
The type of the calculation is predefined by the type of calculation: Triggered, asset degradation, or asset health.
Calculation Group
Select a group to arrange or filter calculations. This is optional.
Calculation Classification
Select a classification to arrange or filter calculations. This is optional.
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.
Result value type
Select whether the calculation result value type will be a derived value or a percentage of the maximum value.
4.
Select the Calculation tab.
5.
Select the type of expression. A calculation can be based on:
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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
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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
6.
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.
7.
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:
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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 Asset Health Calculation Variables.
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Operators (such as, add or multiply): Type the operator in the format shown in Using Logical Operators in Calculations.
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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:
The variables “Input1” and “Input2” are placeholders for data. When the calculation is evaluated, APM gets the current values of the inputs.
8.
Select the States tab to add a state to the calculation. For more information, see Creating an Asset Health Calculation State.
9.
Select the Details tab to define calculation details. For more information, see Assigning Asset Health Calculation Details.
10.
Select the Description tab to enter a description about the asset health calculation.