Calculation Points are a special type of internal point that you can use to perform simple calculations on data in the ClearSCADA database. ClearSCADA derives a value for a Calculation Point by evaluating an expression. An expression is a combination of references to database items (tags), symbols and operators. The expression can include conditions as well as arithmetic and logical functions.
Internal points together with Logic functions can be used to perform calculations in a similar way to Calculation points, but are used for more complex calculations.
ClearSCADA supports four types of Calculation Point:
- Analog Calculation point—A point that can have a value in a range of numeric values
- Digital Calculation point—A 1-, 2-, or 3-bit point that can be in one of several fixed states
- String Calculation point—A point that has a text string value, rather than a numeric value
- Time Calculation point—A point that has a date/time value.
You can specify when Calculation points should evaluate expressions:
- An operator can execute expressions by selecting the Execute pick action
- ClearSCADA should execute expressions periodically
- ClearSCADA should execute expressions when it processes some kinds of tag in the expression.
Further Information
Configuring and Working with Calculation Points
Expressions: see Welcome to the Guide to Expressions in the ClearSCADA Guide to Expressions.
Internal Points:see Internal Points
Tags: see Tags in the ClearSCADA Guide to Expressions.
Configuration point pick actions: see Using Calculation Point Specific Actions.