HistorianBefore Aggregate
When the Before aggregate function is called with a timestamp (Start time), the previous valid value before Start time will be fetched. This search is performed between Start time and (Start time – MaxDurationSec). The call for the aggregation is initiated by the source client. The custom aggregations do not require any interval value. The default value for MaxDurationSec is 100 days.
Note: To change the value of MaxDurationSec navigate to
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Intellution, Inc.\iHistorian\HDAServer. Create a string value with name MaxDurationSec and provide the value in seconds.Start: Apr-01-2002 12:00:10 End: NA Interval: NA
| Timestamp | Value | Quality |
|
Mar-01-2002 12:01:30 | 98765 | Raw, Good |