EasyUA Reference
HistoryReadModified(IList<HistoryReadValueId>,ReadRawModifiedDetails,TimestampsToReturn,RequestSettings) Method
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EasyUA Assembly > Advosol.EasyUA Namespace > Session Class > HistoryReadModified Method : HistoryReadModified(IList<HistoryReadValueId>,ReadRawModifiedDetails,TimestampsToReturn,RequestSettings) Method

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, 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.

Glossary Item Box

Reads the history of modified variable values synchronously from the OPC server.

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 value As List(Of HistoryDataReadResult)
 
value = instance.HistoryReadModified(nodesToRead, details, timestampsToReturn, settings)
C# 
public List<HistoryDataReadResult> HistoryReadModified( 
   IList<HistoryReadValueId> nodesToRead,
   ReadRawModifiedDetails details,
   TimestampsToReturn timestampsToReturn,
   RequestSettings settings
)

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, 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 and time interval. A continuation point is included for a node if not all results could be returned.

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

See Also

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