IsUnknown
- Last UpdatedNov 22, 2022
- 1 minute read
- PI System
- PI Manual Logger 2017 R2
- Visualization
Syntax
IsUnknown(Expression)
Arguments
|
Argument |
Data Type |
Description |
|---|---|---|
|
Expression |
Any |
Any valid expression |
Returns
Returns "true" if the expression cannot be evaluated due to missing or unknown data, otherwise returns "false."
Examples
IsUnknown(PreviousTime("TI001.ML"))
This example returns "true" if the previous time of the tag TI001.ML is unknown, that is, could not be found, otherwise it returns "false."