General

Icon :

If you do not know upfront which OPC server 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 Server Dialog (OpcServerDialog class) allows the user to select the OPC server interactively from the list of OPC Data Access servers installed on a particular machine.

Here is an example of OPC Server dialog in action:

The ServerFamilies property of the dialog determines whether OPC Data Access servers, OPC Alarms&Events servers, other servers, or a combination of them will be browsed. By default, all server families are browsed. In order to limit the browsing to OPC Data Access servers only, set the ServerFamilies property to the OpcDataAccess enumeration member.

To run the dialog, set the Location property to the name of the computer that is to be browsed, and call the ShowDialog method. If the result is equal to DialogResult.OK, the user has selected the OPC Data Access server, and information about it can be retrieved from the ServerElement property.

.NET

// This example shows how to let the user browse for an OPC "Classic" server.

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

namespace FormsDocExamples._OpcServerDialog
{
    static class ShowDialog
    {
        public static void Main1(IWin32Window owner)
        {
            var serverDialog = new OpcServerDialog();
            //serverDialog.Location = "";

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

            // Display results
            MessageBox.Show(owner, serverDialog.ServerElement);
        }
    }
}

# This example shows how to let the user browse for an OPC "Classic" server.

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

$serverDialog = New-Object OpcLabs.EasyOpc.Forms.Browsing.OpcServerDialog
#$serverDialog.Location = ""

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

# Display results
Write-Host $serverDialog.ServerElement

# This example shows how to let the user browse for an OPC "Classic" server.

# 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.Forms.Browsing import *


serverDialog = OpcServerDialog()
#serverDialog.Location = ''

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

# Display results.
print('ServerElement: ', serverDialog.ServerElement, sep='')

COM

// This example shows how to let the user browse for an OPC "Classic" server.

class procedure ShowDialog.Main;
var
  ServerDialog: OpcLabs_EasyOpcForms_TLB._OpcServerDialog;
begin
  // Instantiate the dialog object
  ServerDialog := CoOpcServerDialog.Create;

  ServerDialog.ShowDialog(nil);

  // Display results
  WriteLn(ServerDialog.ServerElement.ToString);
end;

Rem This example shows how to let the user browse for an OPC "Classic" server.

Private Sub ShowDialog_Main_Command_Click()
    OutputText = ""

    ' Instantiate the dialog object
    Dim serverDialog As New OpcServerDialog
    Dim DialogResult
    DialogResult = serverDialog.ShowDialog
    
    OutputText = OutputText & DialogResult & vbCrLf
    If DialogResult <> 1 Then   ' OK
        Exit Sub
    End If
    
    ' Display results
    OutputText = OutputText & serverDialog.ServerElement & vbCrLf
End Sub

Rem This example shows how to let the user browse for an OPC "Classic" server.

Option Explicit

Const DialogResult_OK = 1

Dim ServerDialog: Set ServerDialog = CreateObject("OpcLabs.EasyOpc.Forms.Browsing.OpcServerDialog")
'ServerDialog.Location = ""
Dim dialogResult: dialogResult = ServerDialog.ShowDialog
WScript.Echo dialogResult

If dialogResult <> DialogResult_OK Then
    WScript.Quit
End If

' Display results
WScript.Echo ServerDialog.ServerElement

Advanced

If you want to change the parameters of the client objects the component uses to perform its OPC operations, you can use the DAClientSelector Property or the AEClientSelector Property.