BrowseDataVariables Method (

Browses the Data Variables, specifying an endpoint descriptor, and a starting Node Id.

Syntax

Visual Basic
C#
C++/CLI

'Declaration
 
<NotNullAttribute()>
Function BrowseDataVariables( _
   ByVal endpointDescriptorString As String, _
   ByVal nodeDescriptorString As String _
) As UANodeElementCollection

'Usage
 
Dim instance As _EasyUAClient
Dim endpointDescriptorString As String
Dim nodeDescriptorString As String
Dim value As UANodeElementCollection
 
value = instance.BrowseDataVariables(endpointDescriptorString, nodeDescriptorString)

[NotNull()]
UANodeElementCollection BrowseDataVariables( 
   string endpointDescriptorString,
   string nodeDescriptorString
)

[NotNull()]
UANodeElementCollection^ BrowseDataVariables( 
   String^ endpointDescriptorString,
   String^ nodeDescriptorString
)

Parameters

endpointDescriptorString

Endpoint descriptor. Identifies the OPC-UA server.

The value represents an OPC UA endpoint descriptor string. Any string can be passed to this parameter (i.e. will not cause System.ArgumentException), but not all values make sense and will work when an operation using them is attempted. The OPC UA endpoint descriptor string is typically the URL of the server endpoint.

The value of this parameter can be null (Nothing in Visual Basic).

nodeDescriptorString

Node descriptor. Identifies the node in OPC server's address space.

The value of this parameter can be null (Nothing in Visual Basic).

Return Value

The method returns a node element collection, which contains OpcLabs.EasyOpc.UA.AddressSpace.UANodeElement values. Each element contains information about a particular node found.

This method never returns null (Nothing in Visual Basic).

The individual elements of the returned value are never null (Nothing in Visual Basic).

Remarks

This member or type is for use from COM. It is not meant to be used from .NET or Python. Refer to the corresponding .NET member or type instead, if you are developing in .NET or Python.

Example

// This example shows how to obtain data variables under the "Server" node
// in the address space.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
// OPC client and subscriber examples in Object Pascal (Delphi) on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-OP .
// Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own
// a commercial license in order to use Online Forums, and we reply to every post.

class procedure BrowseDataVariables.Main;
var
  Client: OpcLabs_EasyOpcUA_TLB._EasyUAClient;
  Count: Cardinal;
  Element: OleVariant;
  EndpointDescriptor: string;
  NodeElement: _UANodeElement;
  NodeElementEnumerator: IEnumVariant;
  NodeElements: _UANodeElementCollection;
  ServerNodeId: _UANodeId;
begin
  EndpointDescriptor := 
    //'http://opcua.demo-this.com:51211/UA/SampleServer';
    //'https://opcua.demo-this.com:51212/UA/SampleServer/';
    'opc.tcp://opcua.demo-this.com:51210/UA/SampleServer';

  // Instantiate the client object
  Client := CoEasyUAClient.Create;

  // Obtain variables under "Server" node
  ServerNodeId := CoUANodeId.Create;
  ServerNodeId.StandardName := 'Server';
  try
    NodeElements := Client.BrowseDataVariables(EndpointDescriptor, ServerNodeId.ExpandedText);
  except
    on E: EOleException do
    begin
      WriteLn(Format('*** Failure: %s', [E.GetBaseException.Message]));
      Exit;
    end;
  end;

  // Display results
  NodeElementEnumerator := NodeElements.GetEnumerator;
  while (NodeElementEnumerator.Next(1, Element, Count) = S_OK) do
  begin
    NodeElement := IUnknown(Element) as _UANodeElement;
    WriteLn;
    WriteLn('nodeElement.NodeId: ', NodeElement.NodeId.ToString);
    WriteLn('nodeElement.NodeId.ExpandedText: ', NodeElement.NodeId.ExpandedText);
    WriteLn('nodeElement.DisplayName: ', NodeElement.DisplayName);
  end;

  // Example output:
  //
  //nodeElement.NodeId: Server_ServerStatus
  //nodeElement.NodeId.ExpandedText: nsu=http://opcfoundation.org/UA/ ;i=2256
  //nodeElement.DisplayName: ServerStatus
end;

// This example shows how to obtain data variables under the "Server" node
// in the address space.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
// OPC client and subscriber examples in PHP on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-PHP .
// Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own
// a commercial license in order to use Online Forums, and we reply to every post.

$EndpointDescriptor = new COM("OpcLabs.EasyOpc.UA.UAEndpointDescriptor");
$EndpointDescriptor->UrlString = 
    //"http://opcua.demo-this.com:51211/UA/SampleServer";
    //"https://opcua.demo-this.com:51212/UA/SampleServer/";
    "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer";

// Instantiate the client object
$Client = new COM("OpcLabs.EasyOpc.UA.EasyUAClient");

// Obtain variables under "Server" node
$ServerNodeId = new COM("OpcLabs.EasyOpc.UA.AddressSpace.UANodeId");
$ServerNodeId->StandardName = "Server";

try
{
    $NodeElements = $Client->BrowseDataVariables($EndpointDescriptor, $ServerNodeId->ExpandedText);
}
catch (com_exception $e)
{
    printf("*** Failure: %s\n", $e->getMessage());
    exit();
}

// Display results
foreach ($NodeElements as $NodeElement)
{
    printf("\n");
    printf("nodeElement.NodeId: %s\n", $NodeElement->NodeId);
    printf("nodeElement.NodeId.ExpandedText: %s\n", $NodeElement->NodeId->ExpandedText);
    printf("nodeElement.DisplayName: %s\n", $NodeElement->DisplayName);
}

// Example output:
//
//nodeElement.NodeId: Server_ServerStatus
//nodeElement.NodeId.ExpandedText: nsu=http://opcfoundation.org/UA/ ;i=2256
//nodeElement.DisplayName: ServerStatus

REM This example shows how to obtain data variables under the "Server" node
REM in the address space.
REM
REM Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
REM OPC client and subscriber examples in Visual Basic on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-VB .
REM Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own
REM a commercial license in order to use Online Forums, and we reply to every post.

Public Sub BrowseDataVariables_Main_Command_Click()
    OutputText = ""

    Dim endpointDescriptor As String
    'endpointDescriptor = "http://opcua.demo-this.com:51211/UA/SampleServer"
    'endpointDescriptor = "https://opcua.demo-this.com:51212/UA/SampleServer/"
    endpointDescriptor = "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"

    ' Instantiate the client object
    Dim Client As New EasyUAClient

    ' Obtain variables under "Server" node
    Dim serverNodeId As New UANodeId
    serverNodeId.StandardName = "Server"
    
    On Error Resume Next
    Dim NodeElements As UANodeElementCollection
    Set NodeElements = Client.BrowseDataVariables(endpointDescriptor, serverNodeId.expandedText)
    If Err.Number <> 0 Then
        OutputText = OutputText & "*** Failure: " & Err.Source & ": " & Err.Description & vbCrLf
        Exit Sub
    End If
    On Error GoTo 0

    ' Display results
    Dim NodeElement: For Each NodeElement In NodeElements
        OutputText = OutputText & vbCrLf
        OutputText = OutputText & "nodeElement.NodeId: " & NodeElement.NodeId & vbCrLf
        OutputText = OutputText & "nodeElement.NodeId.ExpandedText: " & NodeElement.NodeId.expandedText & vbCrLf
        OutputText = OutputText & "nodeElement.DisplayName: " & NodeElement.DisplayName & vbCrLf
    Next
    
    ' Example output:
    '
    'nodeElement.NodeId: Server_ServerStatus
    'nodeElement.NodeId.ExpandedText: nsu=http://opcfoundation.org/UA/ ;i=2256
    'nodeElement.DisplayName: ServerStatus
End Sub

Rem This example shows how to obtain data variables under the "Server" node in the address space.
Rem
Rem Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
Rem OPC client and subscriber examples in VBScript on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-VBScript .
Rem Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own
Rem a commercial license in order to use Online Forums, and we reply to every post.

Option Explicit

Dim endpointDescriptor: endpointDescriptor = _
    "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
    '"http://opcua.demo-this.com:51211/UA/SampleServer"  
    '"https://opcua.demo-this.com:51212/UA/SampleServer/"

' Instantiate the client object
Dim Client: Set Client = CreateObject("OpcLabs.EasyOpc.UA.EasyUAClient")

' Obtain variables under "Server" node
Dim ServerNodeId: Set ServerNodeId = CreateObject("OpcLabs.EasyOpc.UA.AddressSpace.UANodeId")
ServerNodeId.StandardName = "Server"
On Error Resume Next
Dim NodeElementCollection: Set NodeElementCollection = Client.BrowseDataVariables(endpointDescriptor, ServerNodeId.ExpandedText)
If Err.Number <> 0 Then
    WScript.Echo "*** Failure: " & Err.Source & ": " & Err.Description
    WScript.Quit
End If
On Error Goto 0

' Display results
Dim NodeElement: For Each NodeElement In NodeElementCollection
    WScript.Echo 
    WScript.Echo "nodeElement.NodeId: " & NodeElement.NodeId
    WScript.Echo "nodeElement.NodeId.ExpandedText: " & NodeElement.NodeId.ExpandedText
    WScript.Echo "nodeElement.DisplayName: " & NodeElement.DisplayName
Next

' Example output:
'
'nodeElement.NodeId: Server_ServerStatus
'nodeElement.NodeId.ExpandedText: nsu=http://opcfoundation.org/UA/ ;i=2256
'nodeElement.DisplayName: ServerStatus

Requirements

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

Reference

_EasyUAClient Interface
_EasyUAClient Members

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Missing some example? Ask us for it on our Online Forums! You do not have to own a commercial license in order to use Online Forums, and we reply to every post.