OPC Studio User's Guide and Reference
DAItemDescriptor Constructor(DAItemDescriptor)



OpcLabs.EasyOpcClassicCore Assembly > OpcLabs.EasyOpc.DataAccess Namespace > DAItemDescriptor Class > DAItemDescriptor Constructor : DAItemDescriptor Constructor(DAItemDescriptor)
An item descriptor object to be copied from.

Because the DAItemDescriptor has an implicit conversion from System.String and OpcLabs.EasyOpc.DataAccess.AddressSpace.DANodeElement, in languages that support implicit conversion operators (such as C# or VB.NET), you can simply use a string (representing the qualified name of the node), or a OpcLabs.EasyOpc.DataAccess.AddressSpace.DANodeElement object (result from OPC browsing), in place of this parameter, and the corresponding OPC DA item descriptor will be constructed automatically. When the implicit conversion operators are not supported (such as with Python.NET), you can use the FromString or FromDANodeElement static method instead.

The value of this parameter cannot be null (Nothing in Visual Basic).

Initializes a new copy of the DAItemDescriptor object.
Syntax
'Declaration
 
Public Function New( _
   ByVal itemDescriptor As DAItemDescriptor _
)
'Usage
 
Dim itemDescriptor As DAItemDescriptor
 
Dim instance As New DAItemDescriptor(itemDescriptor)
public DAItemDescriptor( 
   DAItemDescriptor itemDescriptor
)
public:
DAItemDescriptor( 
   DAItemDescriptor^ itemDescriptor
)

Parameters

itemDescriptor
An item descriptor object to be copied from.

Because the DAItemDescriptor has an implicit conversion from System.String and OpcLabs.EasyOpc.DataAccess.AddressSpace.DANodeElement, in languages that support implicit conversion operators (such as C# or VB.NET), you can simply use a string (representing the qualified name of the node), or a OpcLabs.EasyOpc.DataAccess.AddressSpace.DANodeElement object (result from OPC browsing), in place of this parameter, and the corresponding OPC DA item descriptor will be constructed automatically. When the implicit conversion operators are not supported (such as with Python.NET), you can use the FromString or FromDANodeElement static method instead.

The value of this parameter cannot be null (Nothing in Visual Basic).

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.

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