QuickOPC User's Guide and Reference
BrowseTree(IEasyDAClient,ServerDescriptor,DANodeDescriptor) Method



OpcLabs.EasyOpcClassicCore Assembly > OpcLabs.EasyOpc.DataAccess.Extensions Namespace > IEasyDAClientExtension2 Class > BrowseTree Method : BrowseTree(IEasyDAClient,ServerDescriptor,DANodeDescriptor) Method
The client object that will perform the operation.
Server descriptor. Identifies the OPC-DA server.
Starting node descriptor. Identifies the node in OPC server's address space.
Allows to traverse through OPC DA address space data nodes under the specified node.
Syntax
'Declaration
 
<ExtensionAttribute()>
<NotNullAttribute()>
Public Overloads Shared Function BrowseTree( _
   ByVal client As IEasyDAClient, _
   ByVal serverDescriptor As ServerDescriptor, _
   ByVal nodeDescriptor As DANodeDescriptor _
) As ITreeTraversable(Of DANodeTreePosition)
'Usage
 
Dim client As IEasyDAClient
Dim serverDescriptor As ServerDescriptor
Dim nodeDescriptor As DANodeDescriptor
Dim value As ITreeTraversable(Of DANodeTreePosition)
 
value = IEasyDAClientExtension2.BrowseTree(client, serverDescriptor, nodeDescriptor)

Parameters

client
The client object that will perform the operation.
serverDescriptor
Server descriptor. Identifies the OPC-DA server.
nodeDescriptor
Starting node descriptor. Identifies the node in OPC server's address space.

Return Value

Returns an enumerator of tree positions that will traverse through all nodes specified.
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.

Remarks

If you want to enumerate through a sequence of the tree nodes, convert the result to a sequence using the OpcLabs.BaseLib.Graphs.Extensions.ITreeTraversableExtension.ToEnumerable<T> method.

The method automatically prevents recursion into nodes that have already been traversed.

The root position in a tree will correspond to the specified starting node. The OpcLabs.EasyOpc.DataAccess.Graphs.DANodeTreePosition object for the root is special one, in that from its OpcLabs.EasyOpc.DataAccess.AddressSpace.DANodeElement properties, only its ItemId is filled in.

You can obtain nodeDescriptor e.g. by calling one of the browsing methods on OpcLabs.EasyOpc.DataAccess.IEasyDAClient interface.

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