Filter expressions

Use a filter expression in a PI DataLink function to filter recorded values with a Boolean performance equation. PI DataLink removes data for which the expression evaluates as false.

PI DataLink applies the filter expression to the raw data retrieved (and not values that result from the calculation itself). For example, adding the simple filter expression 'sinusoid' < 70 to the Calculated Data function would remove all values equal to or greater than 70 from the calculation.

Filter expressions can contain any valid Boolean performance equation; however, data items in filter expressions must reference a PI point. You can build complex expressions. For example, you might use filter expressions to remove atypical peaks in recorded values.

If available, select the Mark as filtered check box to insert the label Filtered in place of a value or block of values that the function filtered from the output based on the filter expression.

For more information, see Performance equation syntax.