An OPC-UA Attribute Point is a connectivity point that represents an OPC Unified Architecture (OPC-UA) attribute on a node.

Point, Parameters, and Arguments Types

For operations listed below, following classes are used for the point itself, the operation parameters and operation arguments:

Operation	Point Type	Parameters Type	Arguments Type
Read	UAAttributePoint Class	UAAttributePointReadParameters Class	UAAttributePointReadArguments Class
Subscribe		UAAttributePointSubscribeParameters Class	UAAttributePointSubscribeArguments Class
Write		UAAttributePointWriteParameters Class	UAAttributePointWriteArguments Class

Type Aliases

You can use following type aliases for this point type:

• opcuaattribute
• ua

Friendly Topic Syntax

In order to describe the point and its subscription parameters, use the following sequence:

   EndpointDescriptorString, NodeId [, [AttributeId] [, SamplingInterval]]

Where:

• EndpointDescriptorString is a descriptor string for the endpoint, i.e. a URL string of the resource.
• NodeId is a node Id. Contains an identifier for a node in a server's address space, together with a complete namespace URI.
• AttributeId identifies an attribute of a node. It can be symbolic or numeric value. Case insensitive. Defaults to the Value attribute.
• SamplingInterval is the fastest rate at which the monitored items should be accessed and evaluated (in milliseconds). Defaults to 1000 milliseconds.

If the point or parameters differ from the default in other properties, the friendly topic syntax cannot be used.

Remarks 

For valid symbolic values of the AttributeId, see UAAttributeId Enumeration Fields.

Examples

   "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer", "nsu=http://test.org/UA/Data/;i=11218"

   "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer", "nsu=http://test.org/UA/Data/;i=11218", "DataType"

   "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer", "nsu=http://test.org/UA/Data/;i=11218", , "5000"

XML Topic Syntax

The XML topic syntax is capable to fully describe the point and parameters. It is currently not documented, and is subject to change.