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.NET Based OPC UA Client/Server SDK
2.6.0.418
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.NET Based OPC UA Client/Server SDK
2.6.0.418
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Asynchronously reads historical values or events of one or more nodes. More...
Inherits UnifiedAutomation.UaBase.IServiceRequest, and UnifiedAutomation.UaBase.IEncodeable.
Public Member Functions | |
| HistoryReadRequest () | |
| The default constructor. More... | |
| virtual void | Encode (IEncoder encoder) |
| virtual void | Decode (IDecoder decoder) |
| virtual bool | IsEqual (IEncodeable encodeable) |
| Checks if encodeable is the same object or has the same content More... | |
| virtual object | Clone () |
Properties | |
| RequestHeader | RequestHeader [get, set] |
| ExtensionObject | HistoryReadDetails [get, set] |
| The details define the types of history reads that can be performed. More... | |
| TimestampsToReturn | TimestampsToReturn [get, set] |
| An enumeration that specifies the timestamps to be returned for each requested variable value attribute. More... | |
| bool | ReleaseContinuationPoints [get, set] |
| A Boolean parameter indicating whether to reset passed continuation points. More... | |
| HistoryReadValueIdCollection | NodesToRead [get, set] |
| contains the list of items upon which the historical retrieval is to be performed. More... | |
| virtual ExpandedNodeId | TypeId [get] |
| virtual ExpandedNodeId | BinaryEncodingId [get] |
| virtual ExpandedNodeId | XmlEncodingId [get] |
 Properties inherited from UnifiedAutomation.UaBase.IServiceRequest | |
| RequestHeader | RequestHeader [get, set] |
| The header for the request. More... | |
| Properties inherited from UnifiedAutomation.UaBase.IEncodeable | |
| ExpandedNodeId | TypeId [get] |
| Returns the UA type identifier for the encodable type. More... | |
| ExpandedNodeId | BinaryEncodingId [get] |
| Returns the UA type identifier for the default binary encoding for the type. More... | |
| ExpandedNodeId | XmlEncodingId [get] |
| Returns the UA type identifier for the default XML encoding for the type. More... | |
Asynchronously reads historical values or events of one or more nodes.
For constructed attribute values whose elements are indexed, such as an array, this service allows Clients to read the entire set of indexed values as a composite, to read individual elements or to read ranges of elements of the composite. Servers may make historical values available to Clients using this service, although the historical values themselves are not visible in the address space.
The continuationPoint parameter in the HistoryRead is used to mark a point from which to continue the read if not all values could be returned in one response. The value is opaque for the Client and is only used to maintain the state information for the Server to continue from. A Server may use the timestamp of the last returned data item if the timestamp is unique. This can reduce the need in the Server to store state information for the continuation point.
In some cases it may take longer than the Client timeout hint to read the data for all nodes to read. Then the Server may return zero results with a continuation point for the affected nodes before the timeout expires. That allows the Server to resume the data acquisition on the next Client read call.
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inline |
The default constructor.
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inlinevirtual |
Checks if encodeable is the same object or has the same content
| encodeable |
Implements UnifiedAutomation.UaBase.IEncodeable.
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getset |
The details define the types of history reads that can be performed.
The HistoryReadDetails parameter type is an extensible parameter. It may contain one of the following: ReadEventDetails, ReadRawModifiedDetails, ReadProcessedDetails, ReadAtTimeDetails.
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getset |
contains the list of items upon which the historical retrieval is to be performed.
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getset |
A Boolean parameter indicating whether to reset passed continuation points.
It has the following values:
A Client shall always use the continuation point returned by a HistoryRead response to free the resources for the continuation point in the Server. If the Client does not want to get the next set of historical information, HistoryRead shall be called with this parameter set to TRUE.
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getset |
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getset |
An enumeration that specifies the timestamps to be returned for each requested variable value attribute.
Specifying a TimestampsToReturn of NEITHER is not valid. A Server shall return a Bad_InvalidTimestampArgument StatusCode in this case.