OPC Studio User's Guide and Reference
BrowseProperties Method (_EasyDAClient)
Example 



OpcLabs.EasyOpcClassic Assembly > OpcLabs.EasyOpc.DataAccess.ComTypes Namespace > _EasyDAClient Interface : BrowseProperties Method
The OPC server involved in the operation.
Descriptor of the node for which the properties will be browsed.
Browse for available item properties of a specified OPC item. Specify server descriptor, and node descriptor.
Syntax
'Declaration
 
<ElementsNotNullAttribute()>
<NotNullAttribute()>
Function BrowseProperties( _
   ByVal serverDescriptor As Object, _
   ByVal nodeDescriptor As Object _
) As DAPropertyElementCollection
'Usage
 
Dim instance As _EasyDAClient
Dim serverDescriptor As Object
Dim nodeDescriptor As Object
Dim value As DAPropertyElementCollection
 
value = instance.BrowseProperties(serverDescriptor, nodeDescriptor)
[ElementsNotNull()]
[NotNull()]
DAPropertyElementCollection BrowseProperties( 
   object serverDescriptor,
   object nodeDescriptor
)
[ElementsNotNull()]
[NotNull()]
DAPropertyElementCollection^ BrowseProperties( 
   Object^ serverDescriptor,
   Object^ nodeDescriptor
) 

Parameters

serverDescriptor
The OPC server involved in the operation.
nodeDescriptor
Descriptor of the node for which the properties will be browsed.

Return Value

The method returns a keyed collection of OpcLabs.EasyOpc.DataAccess.AddressSpace.DAPropertyElement values, each containing information about a particular property found. The keys of the keyed collection are the IDs of the properties.
Exceptions
ExceptionDescription

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.

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.

Remarks
Using implicit conversions, you can pass an item ID in place of node descriptor.
Example

COM

// This example shows how to enumerate all properties of an OPC item. For each property, it displays its Id and description.
//
// Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

class procedure BrowseProperties.Main;
var
  Client: OpcLabs_EasyOpcClassic_TLB._EasyDAClient;
  Count: Cardinal;
  Element: OleVariant;
  ServerDescriptor: _ServerDescriptor;
  NodeDescriptor: _DANodeDescriptor;
  PropertyElement: _DAPropertyElement;
  PropertyElementEnumerator: IEnumVariant;
  PropertyElements: _DAPropertyElementCollection;
begin
  ServerDescriptor := CoServerDescriptor.Create;
  ServerDescriptor.ServerClass := 'OPCLabs.KitServer.2';

  NodeDescriptor := CoDANodeDescriptor.Create;
  NodeDescriptor.ItemId := 'Simulation.Random';

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

  try
    PropertyElements := Client.BrowseProperties(
      ServerDescriptor,
      NodeDescriptor);
  except
    on E: EOleException do
    begin
      WriteLn(Format('*** Failure: %s', [E.GetBaseException.Message]));
      Exit;
    end;
  end;

  PropertyElementEnumerator := PropertyElements.GetEnumerator;
  while (PropertyElementEnumerator.Next(1, Element, Count) = S_OK) do
  begin
    PropertyElement := IUnknown(Element) as _DAPropertyElement;
    WriteLn('PropertyElements("', PropertyElement.PropertyId.NumericalValue, '").Description: ', PropertyElement.Description);
  end;
end;
// This example shows how to enumerate all properties of an OPC item. For each property, it displays its Id and description.
//
// Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

$ServerDescriptor = new COM("OpcLabs.EasyOpc.ServerDescriptor");
$ServerDescriptor->ServerClass = "OPCLabs.KitServer.2";

$NodeDescriptor = new COM("OpcLabs.EasyOpc.DataAccess.DANodeDescriptor");
$NodeDescriptor->ItemID = "Simulation.Random";

$Client = new COM("OpcLabs.EasyOpc.DataAccess.EasyDAClient");

try
{
    $PropertyElements = $Client->BrowseProperties($ServerDescriptor, $NodeDescriptor);
}
catch (com_exception $e)
{
    printf("*** Failure: %s\n", $e->getMessage());
    Exit();
}

foreach ($PropertyElements as $PropertyElement)
{
    printf("PropertyElements(\"s\").Descriptions\n", $PropertyElement->PropertyID->NumericalValue, $PropertyElement->Description);
}
REM This example shows how to enumerate all properties of an OPC item. For each property, it displays its Id and description.
REM
REM Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

Private Sub BrowseProperties_Main_Command_Click()
    OutputText = ""
    
    Dim serverDescriptor As New serverDescriptor
    serverDescriptor.ServerClass = "OPCLabs.KitServer.2"
    
    Dim nodeDescriptor As New DANodeDescriptor
    nodeDescriptor.itemId = "Simulation.Random"
    
    ' Instantiate the client object
    Dim client As New EasyDAClient

    On Error Resume Next
    Dim propertyElements As DAPropertyElementCollection
    Set propertyElements = client.BrowseProperties(serverDescriptor, nodeDescriptor)
    If Err.Number <> 0 Then
        OutputText = OutputText & "*** Failure: " & Err.Source & ": " & Err.Description & vbCrLf
        Exit Sub
    End If
    On Error GoTo 0

    Dim propertyElement: For Each propertyElement In propertyElements
        OutputText = OutputText & "propertyElements(""" & propertyElement.propertyId.NumericalValue & """).Description: " & propertyElement.Description & vbCrLf
    Next
End Sub
Rem This example shows how to enumerate all properties of an OPC item. For each property, it displays its Id and description.
Rem
Rem Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

Option Explicit

Dim ServerDescriptor: Set ServerDescriptor = CreateObject("OpcLabs.EasyOpc.ServerDescriptor")
ServerDescriptor.ServerClass = "OPCLabs.KitServer.2"

Dim NodeDescriptor: Set NodeDescriptor = CreateObject("OpcLabs.EasyOpc.DataAccess.DANodeDescriptor")
NodeDescriptor.ItemID = "Simulation.Random"

Dim EasyDAClient: Set EasyDAClient = CreateObject("OpcLabs.EasyOpc.DataAccess.EasyDAClient")
On Error Resume Next
Dim PropertyElements: Set PropertyElements = EasyDAClient.BrowseProperties(ServerDescriptor, NodeDescriptor)
If Err.Number <> 0 Then
    WScript.Echo "*** Failure: " & Err.Source & ": " & Err.Description
    WScript.Quit
End If
On Error Goto 0

Dim PropertyElement: For Each PropertyElement In PropertyElements
    WScript.Echo "PropertyElements(""" & PropertyElement.PropertyID.NumericalValue & """).Description: " & PropertyElement.Description
Next
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