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General

Icon:

If you do not know upfront which OPC-UA server and its endpoint to connect to, and do not have this information from any other source, your application will need to allow the user select the OPC server(s) to work with. The OPC-UA Endpoint Dialog (UAEndpointDialog class) allows the user to select the OPC server and its endpoint interactively from the list of OPC Unified Architecture servers provided by a LDS (Local Discovery Server) installed on a machine.

Here is an example of OPC-UA Endpoint dialog in action:

To run the dialog, call the ShowDialog method. If the result is equal to DialogResult.OK, the user has selected the OPC UA server, and information about it can be retrieved from the DiscoveryElement property.

Currently, the dialog shows endpoint provided by a LDS (Local Discovery Server) that you set by a static property on the EasyUAClient object. This approach may change in future.

.NET

// This example shows how to let the user browse for an OPC-UA server endpoint.

using System.Windows.Forms;
using OpcLabs.EasyOpc.UA.Forms.Browsing;

namespace UAFormsDocExamples._UAEndpointDialog
{
    static class ShowDialog
    {
        public static void Main1(IWin32Window owner)
        {
            var endpointDialog = new UAEndpointDialog
            {
                DiscoveryHost = "opcua.demo-this.com"
            };

            DialogResult dialogResult = endpointDialog.ShowDialog(owner);
            if (dialogResult != DialogResult.OK)
                return;

            // Display results
            MessageBox.Show(owner, endpointDialog.DiscoveryElement.ToString());
        }
    }
}

# This example shows how to let the user browse for an OPC-UA server endpoint.

using namespace OpcLabs.EasyOpc.UA.Forms.Browsing

# The path below assumes that the current directory is [ProductDir]/Examples-NET/PowerShell/Windows .
Add-Type -Path "../../../Components/Opclabs.QuickOpc/net472/OpcLabs.EasyOpcForms.dll"

# Instantiate the dialog object.
$endpointDialog = New-Object UAEndpointDialog
$endpointDialog.DiscoveryHost = "opcua.demo-this.com"

$dialogResult = $endpointDialog.ShowDialog()
if ($dialogResult -ne [System.Windows.Forms.DialogResult]::OK) {
    return
}

# Display results
Write-Host $endpointDialog.DiscoveryElement

# This example shows how to let the user browse for an OPC-UA server endpoint.

# The QuickOPC package is needed. Install it using "pip install opclabs_quickopc".
import opclabs_quickopc

# Import .NET namespaces.
from System.Windows.Forms import *
from OpcLabs.EasyOpc.UA.Forms.Browsing import *


endpointDialog = UAEndpointDialog()
endpointDialog.DiscoveryHost = 'opcua.demo-this.com'

dialogResult = endpointDialog.ShowDialog()
print(dialogResult)
if dialogResult != DialogResult.OK:
    exit()

# Display results.
print(endpointDialog.DiscoveryElement)

print('Finished.')

COM

// This example shows how to let the user browse for an OPC-UA server endpoint.

#include "stdafx.h"    // Includes "QuickOpc.h", and other commonly used files
#include "ShowDialog.h"

namespace _UAEndpointDialog
{
    void ShowDialog1::Main()
    {
        // Initialize the COM library
        CoInitializeEx(NULL, COINIT_MULTITHREADED);
        {
            // 
            _UAEndpointDialogPtr EndpointDialogPtr(__uuidof(UAEndpointDialog));

            //
            EndpointDialogPtr->DiscoveryHost = L"opcua.demo-this.com";

            // 
            DialogResult dialogResult = EndpointDialogPtr->ShowDialog(NULL);
            _tprintf(_T("%d\n"), dialogResult);

            if (dialogResult == 1/*OK*/)
            {
                // Display results
                _tprintf(_T("%s\n"), (LPCTSTR)CW2CT(EndpointDialogPtr->DiscoveryElement->ToString));
            }
        }
         // Release all interface pointers BEFORE calling CoUninitialize()
        CoUninitialize();
    }
}

// This example shows how to let the user browse for an OPC-UA server endpoint.

class procedure ShowDialog.Main;
var
  EndpointDialog: UAEndpointDialog;
begin
  // Instantiate the dialog object
  EndpointDialog := CoUAEndpointDialog.Create;

  EndpointDialog.DiscoveryHost := 'opcua.demo-this.com';

  EndpointDialog.ShowDialog(nil);
  // IMPROVE: check the dialog result

  // Display results
  WriteLn(EndpointDialog.DiscoveryElement.ToString);
end;

// This example shows how to let the user browse for an OPC-UA server endpoint.

class procedure ShowDialog.Main;
var
  EndpointDialog: OpcLabs_EasyOpcForms_TLB._UAEndpointDialog;
  DialogResult: System_Windows_Forms_TLB.DialogResult;
begin
  // Instantiate the dialog object
  EndpointDialog := CoUAEndpointDialog.Create;

  EndpointDialog.DiscoveryHost := 'opcua.demo-this.com';

  DialogResult := EndpointDialog.ShowDialog(nil);
  WriteLn(DialogResult);

  if DialogResult <> DialogResult_OK then
    Exit;

  // Display results
  WriteLn(EndpointDialog.DiscoveryElement.ToString);
end;

Rem This example shows how to let the user browse for an OPC-UA server endpoint.

Private Sub ShowDialog_Main_Command_Click()
    OutputText = ""

    Dim EndpointDialog As New UAEndpointDialog
    EndpointDialog.DiscoveryHost = "opcua.demo-this.com"
    
    Dim DialogResult
    DialogResult = EndpointDialog.ShowDialog
    
    OutputText = OutputText & DialogResult & vbCrLf
    If DialogResult <> 1 Then   ' OK
        Exit Sub
    End If
    
    ' Display results
    OutputText = OutputText & EndpointDialog.DiscoveryElement & vbCrLf
End Sub

Rem This example shows how to let the user browse for an OPC-UA server endpoint.

Option Explicit

Const DialogResult_OK = 1

Dim EndpointDialog: Set EndpointDialog = CreateObject("OpcLabs.EasyOpc.UA.Forms.Browsing.UAEndpointDialog")
EndpointDialog.DiscoveryHost = "opcua.demo-this.com"

Dim dialogResult: dialogResult = EndpointDialog.ShowDialog
WScript.Echo dialogResult

If dialogResult <> DialogResult_OK Then
    WScript.Quit
End If

' Display results
WScript.Echo EndpointDialog.DiscoveryElement

Advanced

If you want to change the parameters of the client object the component uses to perform its OPC operations, you can use the ClientSelector Property.