OPC Studio User's Guide and Reference
Read(IEasyUAClient,UAEndpointDescriptor,UANodeDescriptor,UAAttributeId) Method



OpcLabs.EasyOpcUA Assembly > OpcLabs.EasyOpc.UA Namespace > IEasyUAClientExtension Class > Read Method : Read(IEasyUAClient,UAEndpointDescriptor,UANodeDescriptor,UAAttributeId) Method
The client object that will perform the operation.
Endpoint descriptor. Identifies the OPC-UA server.
Node descriptor. Identifies the node in OPC server's address space.
Attribute Id. Identifies an attribute of a node.
Reads attribute data from an OPC server. Value, status code, and timestamps are returned. Reads data of a node's Value attribute, using an endpoint descriptor, node Id and an attribute Id.
Syntax
'Declaration
 
<ExtensionAttribute()>
<NotNullAttribute()>
Public Overloads Shared Function Read( _
   ByVal client As IEasyUAClient, _
   ByVal endpointDescriptor As UAEndpointDescriptor, _
   ByVal nodeDescriptor As UANodeDescriptor, _
   ByVal attributeId As UAAttributeId _
) As UAAttributeData
'Usage
 
Dim client As IEasyUAClient
Dim endpointDescriptor As UAEndpointDescriptor
Dim nodeDescriptor As UANodeDescriptor
Dim attributeId As UAAttributeId
Dim value As UAAttributeData
 
value = IEasyUAClientExtension.Read(client, endpointDescriptor, nodeDescriptor, attributeId)

Parameters

client
The client object that will perform the operation.
endpointDescriptor
Endpoint descriptor. Identifies the OPC-UA server.
nodeDescriptor
Node descriptor. Identifies the node in OPC server's address space.
attributeId
Attribute Id. Identifies an attribute of a node.

Return Value

Returns an attribute data object that stores the value of an attribute, together with status code and timestamps.
Exceptions
ExceptionDescription

A null reference (Nothing in Visual Basic) is passed to a method that does not accept it as a valid argument.

This is a usage error, i.e. it will never occur (the exception will not be thrown) in a correctly written program. Your code should not catch this exception.

An invalid enumeration value was used.

This is a usage error, i.e. it will never occur (the exception will not be thrown) in a correctly written program. Your code should not catch this exception.

The OPC UA operation has failed. This operation exception in uniformly used to allow common handling of various kinds of errors. The System.Exception.InnerException always contains information about the actual error cause.

This is an operation error that depends on factors external to your program, and thus cannot be always avoided. Your code must handle it appropriately.

Requirements

Target Platforms: .NET Framework: Windows 10 (selected versions), Windows 11 (selected versions), Windows Server 2016, Windows Server 2022; .NET: Linux, macOS, Microsoft Windows

See Also