Syntax
| Visual Basic (Usage) |  Copy Code |
|---|---|
Dim instance As Session Dim nodesToRead As IList(Of HistoryReadValueId) Dim details As ReadRawModifiedDetails Dim timestampsToReturn As TimestampsToReturn Dim settings As RequestSettings Dim callback As AsyncCallback Dim userData As Object Dim value As IAsyncResult value = instance.BeginHistoryReadModified(nodesToRead, details, timestampsToReturn, settings, callback, userData) | |
| C# | |
|---|---|
public IAsyncResult BeginHistoryReadModified( IList<HistoryReadValueId> nodesToRead, ReadRawModifiedDetails details, TimestampsToReturn timestampsToReturn, RequestSettings settings, AsyncCallback callback, object userData ) | |
Parameters
- nodesToRead
- List of variable nodes to read modified data history from. Includes a continuation point to continue previous read requests.
- details
- Configuration parameters for the history read of modified data. Configuration parameters include - The start time of the requested time interval - The end time of the requested time interval - Setting whether bounding values should be returned - Limitation of the number of results per node
- timestampsToReturn
- Enumeration for the timestamps to return with the values. Possible values are
source,serverorboth. The optionneitheris invalid for history read. - settings
- The general settings for the request. If null, the default settings from the property #DefaultRequestSettings are used.
- callback
- The callback to use when the async call completes.
- userData
- The user data that is passed to the callback.
Return Value
An object which must be passed to the EndHistoryReadModified method.Remarks
This method is used to read modified 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. The
returned number can be limited by the client or the server.
See #ReleaseHistoryContinuationPoints for cleaning up resources in
the server if read should not be continued with the returned
continuation point.
Requirements
Target Platforms: Windows 7/8/10, Windows Server 2003/2008/2012/2015, .NET4.x