Syntax
| Visual Basic (Usage) |  Copy Code |
|---|---|
Dim instance As Session Dim nodesToRead As IList(Of HistoryReadValueId) Dim details As ReadProcessedDetails Dim timestampsToReturn As TimestampsToReturn Dim settings As RequestSettings Dim value As List(Of HistoryDataReadResult) value = instance.HistoryReadProcessed(nodesToRead, details, timestampsToReturn, settings) | |
| C# | |
|---|---|
public List<HistoryDataReadResult> HistoryReadProcessed( IList<HistoryReadValueId> nodesToRead, ReadProcessedDetails details, TimestampsToReturn timestampsToReturn, RequestSettings settings ) | |
Parameters
- nodesToRead
- List of variable nodes to read processed data history from. Includes a continuation point to continue previous read requests.
- details
- Configuration parameters for the history read of processed data. Configuration parameters include - The start time of the requested time domain - The end time of the requested time domain - Time processing interval used to calculate one aggregated value from the raw values - The NodeId of the aggregate used for the calculation of the values
- timestampsToReturn
- Enumeration for the timestamps to return with the values. Possible values are source, server or both. The option neither is invalid for history read.
- settings
- The general settings for the request. If null, the default settings from the property #DefaultRequestSettings are used.
Return Value
Result data for the requested nodes, time domain and aggregates. A continuation point is included for a node if not all results could be returned or processed before the timeout expired.Remarks
This method is used to read processed historical values of one or
more nodes in an ordered sequence for the defined time domain.
Continuation points are used to continue the read of the ordered
sequence if not all data can be returned in one read or if the server
was not able to finish the processing before the timeout expired. The
returned number can be limited by the server and may be 0 if the
server was not able to finish one calculation before the service
timeout expired.
See #ReleaseHistoryContinuationPoints for cleaning
up resources in the server if read should not be continued with the
returned continuation point.
The processed values are calculated with the specified aggregate
based on the raw data in the history database. The server must use
start time, end time, and the resample interval to generate a sequence
of time intervals and then calculate an aggregate for each interval.
Requirements
Target Platforms: Windows 7/8/10, Windows Server 2003/2008/2012/2015, .NET4.x