Browses the specified branch (or root) in OPC server's address space, and returns information about child branches found. Browse for child branches. Specify machine name, server class, element name filter and vendor filter.
Syntax
'Declaration
<ExtensionAttribute()>
<ElementsNotNullAttribute()>
<NotNullAttribute()>
Public Overloads Shared Function BrowseBranches( _
ByVal As IEasyDAClient, _
ByVal As String, _
ByVal As String, _
ByVal As String, _
ByVal As String, _
ByVal As String _
) As DANodeElementCollection
'Usage
Dim client As IEasyDAClient
Dim machineName As String
Dim serverClass As String
Dim parentItemId As String
Dim elementNameFilter As String
Dim vendorFilter As String
Dim value As DANodeElementCollection
value = IEasyDAClientExtension.BrowseBranches(client, machineName, serverClass, parentItemId, elementNameFilter, vendorFilter)
Parameters
- client
- The client object that will perform the operation.
- machineName
- Name of the machine (empty string for local computer).
- serverClass
- Contains ProgID of the OPC server to browse.
- parentItemId
- ID of the parent branch to be browsed (empty string for root)
- elementNameFilter
- A wildcard string to filter the returned element names (empty string for no filtering)
- vendorFilter
- A server specific filter string (empty string for no filtering)
Return Value
The method returns a dictionary of
OpcLabs.EasyOpc.DataAccess.AddressSpace.DANodeElement values, each containing information about a particular branch found. The keys of the dictionary are the names of the branches.
Exceptions
Exception | Description |
System.ArgumentNullException |
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. |
OpcLabs.EasyOpc.OperationModel.OpcException |
The OPC "Classic" (or OPC XML-DA) 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. |
Example
.NET
COM
.NET
// This example shows how to obtain all branches at the root of the address space. For each branch, it displays whether
// it may have child nodes.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
using System;
using OpcLabs.EasyOpc.DataAccess;
using OpcLabs.EasyOpc.DataAccess.AddressSpace;
using OpcLabs.EasyOpc.OperationModel;
namespace DocExamples.DataAccess._EasyDAClient
{
class BrowseBranches
{
public static void Main1()
{
// Instantiate the client object.
var client = new EasyDAClient();
DANodeElementCollection branchElements;
try
{
branchElements = client.BrowseBranches("", "OPCLabs.KitServer.2", "");
}
catch (OpcException opcException)
{
Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message);
return;
}
foreach (DANodeElement branchElement in branchElements)
Console.WriteLine($"BranchElements(\"{branchElement.Name}\").HasChildren: {branchElement.HasChildren}");
}
// Example output:
//
//BranchElements("$ServerControl").HasChildren: True
//BranchElements("Boilers").HasChildren: True
//BranchElements("Simulation").HasChildren: True
//BranchElements("SimulateEvents").HasChildren: True
//BranchElements("Trends").HasChildren: True
//BranchElements("Demo").HasChildren: True
//BranchElements("Greenhouse").HasChildren: True
}
}
# This example shows how to obtain all branches at the root of the address space. For each branch, it displays whether
# it may have child nodes.
#
# Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
# OPC client and subscriber examples in Python on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-Python .
# The QuickOPC package is needed. Install it using "pip install opclabs_quickopc".
import opclabs_quickopc
# Import .NET namespaces.
from OpcLabs.EasyOpc.DataAccess import *
from OpcLabs.EasyOpc.OperationModel import *
# Instantiate the client object.
client = EasyDAClient()
# Perform the operation.
try:
nodeElements = IEasyDAClientExtension.BrowseBranches(client, '', 'OPCLabs.KitServer.2', '')
except OpcException as opcException:
print('*** Failure: ' + opcException.GetBaseException().Message)
exit()
# Display results.
for nodeElement in nodeElements:
print('NodeElements["', nodeElement.Name, '"].HasChildren: ', nodeElement.HasChildren, sep='')
' This example shows how to obtain all branches at the root of the address space. For each branch, it displays whether
' it may have child nodes.
'
' Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
Imports OpcLabs.EasyOpc.DataAccess
Imports OpcLabs.EasyOpc.DataAccess.AddressSpace
Imports OpcLabs.EasyOpc.OperationModel
Namespace DataAccess._EasyDAClient
Partial Friend Class BrowseBranches
Shared Sub Main1()
Dim client = New EasyDAClient()
Dim branchElements As DANodeElementCollection
Try
branchElements = client.BrowseBranches("", "OPCLabs.KitServer.2", "")
Catch opcException As OpcException
Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message)
Exit Sub
End Try
For Each branchElement In branchElements
Console.WriteLine($"BranchElements(""{branchElement.Name}"").HasChildren: {branchElement.HasChildren}")
Next branchElement
End Sub
' Example output
'
'BranchElements("$ServerControl").HasChildren: True
'BranchElements("Boilers").HasChildren: True
'BranchElements("Simulation").HasChildren: True
'BranchElements("SimulateEvents").HasChildren: True
'BranchElements("Trends").HasChildren: True
'BranchElements("Demo").HasChildren: True
'BranchElements("Greenhouse").HasChildren: True
End Class
End Namespace
Rem This example shows how to obtain all branches at the root of the address space. For each branch, it displays whether
Rem it may have child nodes.
Rem
Rem Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
Option Explicit
Dim Client: Set Client = CreateObject("OpcLabs.EasyOpc.DataAccess.EasyDAClient")
On Error Resume Next
Dim BranchElements: Set BranchElements = Client.BrowseBranches("", "OPCLabs.KitServer.2", "")
If Err.Number <> 0 Then
WScript.Echo "*** Failure: " & Err.Source & ": " & Err.Description
WScript.Quit
End If
On Error Goto 0
Dim BranchElement: For Each BranchElement In BranchElements
WScript.Echo "BranchElements(""" & BranchElement.Name & """).HasChildren: " & BranchElement.HasChildren
Next
// This example shows how to obtain all branches at the root of the address space. For each branch, it displays whether
// it may have child nodes.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
using System;
using OpcLabs.EasyOpc.DataAccess;
using OpcLabs.EasyOpc.DataAccess.AddressSpace;
using OpcLabs.EasyOpc.OperationModel;
namespace DocExamples.DataAccess.Xml
{
class BrowseBranches
{
public static void Main1Xml()
{
// Instantiate the client object.
var client = new EasyDAClient();
DANodeElementCollection branchElements;
try
{
branchElements = client.BrowseBranches("http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx");
}
catch (OpcException opcException)
{
Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message);
return;
}
foreach (DANodeElement branchElement in branchElements)
Console.WriteLine($"BranchElements(\"{branchElement.Name}\").HasChildren: {branchElement.HasChildren}");
}
// Example output:
//
//BranchElements("Static").HasChildren: True
//BranchElements("Dynamic").HasChildren: True
}
}
# This example shows how to obtain all branches at the root of the address space. For each branch, it displays whether
# it may have child nodes.
#
# Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
# OPC client and subscriber examples in Python on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-Python .
# The QuickOPC package is needed. Install it using "pip install opclabs_quickopc".
import opclabs_quickopc
# Import .NET namespaces.
from OpcLabs.EasyOpc import *
from OpcLabs.EasyOpc.DataAccess import *
from OpcLabs.EasyOpc.DataAccess.AddressSpace import *
from OpcLabs.EasyOpc.OperationModel import *
# Instantiate the client object.
client = EasyDAClient()
try:
branchElements = IEasyDAClientExtension.BrowseBranches(client, ServerDescriptor('http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx'))
except OpcException as opcException:
print('*** Failure: ' + opcException.GetBaseException().Message, sep='')
exit()
for branchElement in branchElements:
print('BranchElements("', branchElement.Name, '").HasChildren: ', branchElement.HasChildren, sep='')
# Example output:
#
#BranchElements("Static").HasChildren: True
#BranchElements("Dynamic").HasChildren: True
' This example shows how to obtain all branches at the root of the address space. For each branch, it displays whether
' it may have child nodes.
'
' Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
Imports OpcLabs.EasyOpc.DataAccess
Imports OpcLabs.EasyOpc.DataAccess.AddressSpace
Imports OpcLabs.EasyOpc.OperationModel
Namespace DataAccess.Xml
Partial Friend Class BrowseBranches
Shared Sub Main1Xml()
Dim client = New EasyDAClient()
Dim branchElements As DANodeElementCollection
Try
branchElements = client.BrowseBranches("http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx")
Catch opcException As OpcException
Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message)
Exit Sub
End Try
For Each branchElement In branchElements
Console.WriteLine($"BranchElements(""{branchElement.Name}"").HasChildren: {branchElement.HasChildren}")
Next branchElement
End Sub
' Example output
'
'BranchElements("Static").HasChildren: True
'BranchElements("Dynamic").HasChildren: True
End Class
End Namespace
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