General
Icon: 
With OpcBrowseDialog, your application can integrate a dialog with various OPC nodes from which the user can select. This dialog can be configured to serve many different purposes.
Here is an example of the generic OPC browsing dialog in action:
The way the dialog operates is controlled by two main properties:
- Mode.AnchorElementType determines the part of the selection that is given on input and cannot be changed by the user.
- Mode.SelectElementType determines the type of the element that the user needs to select in order to finalize the dialog.
Values of these properties can be selected from the OpcElementType enumeration, which has members for various types of elements that you encounter when working with OPC.
The following chart shows a hierarchy of element types that you can choose from:
For example, let’ say that you set Mode.AnchorElementType to Server, and Mode.SelectElementType to DAProperty. This will cause the dialog to allow the user to browse for an OPC Item (node) on the server you specify, and then for an OPC property on that item.
In this case, before you run the dialog, you need to provide it with values for the InputOutputs.CurrentNodeDescriptor.ServerDescriptor.Location and InputOutputs.CurrentNodeDescriptor.ServerDescriptor.ServerClass properties, because those define your “anchor” element (Server) that the user cannot change. The dialog will only allow the user to finalize it (besides cancelling) after an OPC property is fully selected, because that is your Mode.SelectElementType. After the dialog is successfully finalized, the information about the user’s choice will be available in the Outputs.CurrentNodeElement.DANodeElement and Outputs.CurrentNodeElement.DAPropertyElement properties.
Note that in addition to the “minimal” scenario described above, you can also pre-set the initial node or property, using the InputOutputs.CurrentNodeDescriptor.DANodeDescriptor or InputOutputs.CurrentNodeDescriptor.DAPropertyDescriptor.PropertyId properties, and after the selection is made, these properties will be updated to the new selection as well. This way, if you run the dialog again with the same value, the initial selection will be where the user has left it the last time the dialog was run.
Obviously, the chosen Mode.SelectElementType must be a child or indirect ancestor of chosen Mode.AnchorElementType in the hierarchy. For example, it would be an error to set Mode.AnchorElementType to AECategory and Mode.SelectElementType to DAProperty.
.NET
// This example shows how to let the user browse for an OPC Data Access node in a dialog.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
// OPC client and subscriber examples in C# on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-CSharp .
// 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.
using System.Windows.Forms;
using OpcLabs.EasyOpc.Forms.Browsing;
namespace FormsDocExamples._OpcBrowseDialog
{
static class ShowDialog
{
public static void Main1(IWin32Window owner)
{
var browseDialog = new OpcBrowseDialog();
DialogResult dialogResult = browseDialog.ShowDialog(owner);
if (dialogResult != DialogResult.OK)
return;
// Display results
MessageBox.Show(owner, browseDialog.Outputs.CurrentNodeElement.DANodeElement);
}
}
}
# This example shows how to let the user browse for an OPC Data Access node in a dialog.
#
# Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
# OPC client and subscriber examples in PowerShell on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-PowerShell .
# 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.
# The path below assumes that the current directory is [ProductDir]/Examples-NET/PowerShell/Windows .
Add-Type -Path "../../../Components/Opclabs.QuickOpc/net472/OpcLabs.EasyOpcForms.dll"
$browseDialog = New-Object OpcLabs.EasyOpc.Forms.Browsing.OpcBrowseDialog
$dialogResult = $browseDialog.ShowDialog()
if ($dialogResult -ne [System.Windows.Forms.DialogResult]::OK) {
return
}
# Display results
Write-Host $browseDialog.Outputs.CurrentNodeElement.DANodeElement
' This example shows how to let the user browse for an OPC Data Access node in a dialog.
'
' Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
' OPC client and subscriber examples in VB.NET on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-VBNET .
' 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.
Imports OpcLabs.EasyOpc.Forms.Browsing
Namespace FormsDocExamples._OpcBrowseDialog
Friend Class ShowDialog
Shared Sub Main1(owner As IWin32Window)
Dim browseDialog = New OpcBrowseDialog()
Dim dialogResult As DialogResult = browseDialog.ShowDialog(owner)
If dialogResult <> DialogResult.OK Then
Return
End If
' Display results
MessageBox.Show(owner, browseDialog.Outputs.CurrentNodeElement.DANodeElement)
End Sub
End Class
End Namespace
COM
// This example shows how to let the user browse for an OPC Data Access node.
//
// 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 ShowDialog.Main;
var
BrowseDialog: OpcLabs_EasyOpcForms_TLB._OpcBrowseDialog;
begin
// Instantiate the dialog object
BrowseDialog := CoOpcBrowseDialog.Create;
BrowseDialog.ShowDialog(nil);
// Display results
WriteLn(BrowseDialog.Outputs.CurrentNodeElement.DANodeElement.ToString);
end;
Rem This example shows how to let the user browse for an OPC Data Access node.
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.
Private Sub ShowDialog_Main_Command_Click()
OutputText = ""
' Instantiate the dialog object
Dim browseDialog As New OpcBrowseDialog
Dim DialogResult
DialogResult = browseDialog.ShowDialog
OutputText = OutputText & DialogResult & vbCrLf
If DialogResult <> 1 Then ' OK
Exit Sub
End If
' Display results
OutputText = OutputText & browseDialog.Outputs.CurrentNodeElement.DANodeElement & vbCrLf
End Sub
Rem This example shows how to let the user browse for an OPC Data Access node.
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
Const DialogResult_OK = 1
Dim BrowseDialog: Set BrowseDialog = CreateObject("OpcLabs.EasyOpc.Forms.Browsing.OpcBrowseDialog")
Dim dialogResult: dialogResult = BrowseDialog.ShowDialog
WScript.Echo dialogResult
If dialogResult <> DialogResult_OK Then
WScript.Quit
End If
' Display results
WScript.Echo BrowseDialog.Outputs.CurrentNodeElement.DANodeElement
Python
# This example shows how to let the user browse for an OPC Data Access node in a dialog.
#
# 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 .
# 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.
# 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 *
browseDialog = OpcBrowseDialog()
dialogResult = browseDialog.ShowDialog()
print(dialogResult)
if dialogResult != DialogResult.OK:
exit()
# Display results.
print('DANodeElement: ', browseDialog.Outputs.CurrentNodeElement.DANodeElement, sep='')
Multi-selection
It is also possible to configure the dialog for a multi-selection. In this mode, the user can select zero, one, or more nodes. In order to enable the multi-select mode, set the Mode.MultiSelect property to true. In the multi-select mode, the initial set of the selected nodes (when the dialog is first displayed to the user) is given by the contents of the InputOutputs.SelectionDescriptors collection. When the user makes the selection and accepts it by closing the dialog, this collection is updated, and also, all information about the selected nodes is placed to the Outputs.SelectionElements collection.
Advanced
There are also ways to control some finer aspects of the dialog. For example, the Mode.ShowListBranches property (defaults to true) controls whether the branches of the tree are also displayed in the list view.
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.
See Also
