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.NET Based OPC UA Client/Server SDK
2.6.1.422
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.NET Based OPC UA Client/Server SDK
2.6.1.422
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Reads values and attributes asynchronously from OPC server. More...
Inherits UnifiedAutomation.UaBase.IServiceRequest, and UnifiedAutomation.UaBase.IEncodeable.
Public Member Functions | |
| ReadRequest () | |
| 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] |
| double | MaxAge [get, set] |
| Maximum age of the value to be read in milliseconds. More... | |
| TimestampsToReturn | TimestampsToReturn [get, set] |
| An enumeration that specifies the Timestamps to be returned for each requested Variable Value Attribute. See TimestampsToReturn for more information. More... | |
| ReadValueIdCollection | NodesToRead [get, set] |
| List of Nodes and their Attributes to read. 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... | |
Reads values and attributes asynchronously from OPC server.
The Read Service is used to read one or more attributes of one or more nodes. It allows also reading subsets or single elements of array values and to define a valid age of values to be returned to reduce the need for device reads. Like most other services, the read is optimized for bulk read operations and not for reading single Attribute values. Typically all Node Attributes are readable. For the Value Attribute the Read rights are indicated by the AccessLevel and UserAccessLevel Attribute of the Variable.
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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 |
Maximum age of the value to be read in milliseconds.
The age of the value is based on the difference between the ServerTimestamp and the time when the Server starts processing the request. For example if the Client specifies a maxAge of 500 milliseconds and it takes 100 milliseconds until the Server starts processing the request, the age of the returned value could be 600 milliseconds prior to the time it was requested.
If the Server has one or more values of an Attribute that are within the maximum age, it can return any one of the values or it can read a new value from the data source. The number of values of an Attribute that a Server has depends on the number of MonitoredItems that are defined for the Attribute. In any case, the Client can make no assumption about which copy of the data will be returned.
If the Server does not have a value that is within the maximum age, it shall attempt to read a new value from the data source.
If the Server cannot meet the requested maxAge, it returns its"best effort" value rather than rejecting the request. This may occur when the time it takes the Server to process and return the new data value after it has been accessed is greater than the specified maximum age.
If maxAge is set to 0, the Server shall attempt to read a new value from the data source.
If maxAge is set to the max Int32 value or greater, the Server shall attempt to get a cached value.
Negative values are invalid for maxAge.
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getset |
List of Nodes and their Attributes to read.
For each entry in this list, a StatusCode is returned, and if it indicates success, the Attribute Value is also returned.
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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. See TimestampsToReturn for more information.