BrowseProperties Method (IEasyDAClientExtension)

Browses the available properties of a specified OPC item.

Browse for available item properties. Specify machine name, server class, and item ID.

Syntax

Visual Basic
C#
C++/CLI

'Declaration
 
<ExtensionAttribute()>
<ElementsNotNullAttribute()>
<NotNullAttribute()>
Public Shared Function BrowseProperties( _
   ByVal client As IEasyDAClient, _
   ByVal machineName As String, _
   ByVal serverClass As String, _
   ByVal itemId As String _
) As DAPropertyElementCollection

'Usage
 
Dim client As IEasyDAClient
Dim machineName As String
Dim serverClass As String
Dim itemId As String
Dim value As DAPropertyElementCollection
 
value = IEasyDAClientExtension.BrowseProperties(client, machineName, serverClass, itemId)

[Extension()]
[ElementsNotNull()]
[NotNull()]
public static DAPropertyElementCollection BrowseProperties( 
   IEasyDAClient client,
   string machineName,
   string serverClass,
   string itemId
)

[Extension()]
[ElementsNotNull()]
[NotNull()]
public:
static DAPropertyElementCollection^ BrowseProperties( 
   IEasyDAClient^ client,
   String^ machineName,
   String^ serverClass,
   String^ itemId
)

Parameters

client: The client object that will perform the operation.
machineName: Name of the machine (empty string for local computer).
serverClass: Contains ProgID of the OPC server to browse.
itemId: ID of the item 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

Exception Description

Exception	Description
System.ArgumentNullException	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.
OpcLabs.EasyOpc.OperationModel.OpcException	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.

System.ArgumentNullException

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.

OpcLabs.EasyOpc.OperationModel.OpcException

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.

Example

.NET

// This example shows how to enumerate all properties of an OPC item. For each property, it displays its Id and description.

using System;
using OpcLabs.EasyOpc.DataAccess;
using OpcLabs.EasyOpc.DataAccess.AddressSpace;
using OpcLabs.EasyOpc.OperationModel;

namespace DocExamples.DataAccess._EasyDAClient
{
    class BrowseProperties
    {
        public static void Main1()
        {
            // Instantiate the client object.
            var client = new EasyDAClient();
            DAPropertyElementCollection propertyElements;
            try
            {
                propertyElements = client.BrowseProperties("OPCLabs.KitServer.2", "Simulation.Random");
            }
            catch (OpcException opcException)
            {
                Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message);
                return;
            }

            foreach (DAPropertyElement propertyElement in propertyElements)
                Console.WriteLine($"PropertyElements(\"{propertyElement.PropertyId.NumericalValue}\").Description: {propertyElement.Description}");
        }


        // Example output:
        //
        //PropertyElements("15008").Description: Visible
        //PropertyElements("5").Description: Item Access Rights
        //PropertyElements("2").Description: Item Value
        //PropertyElements("7").Description: Item EU Type
        //PropertyElements("15001").Description: Item Name
        //PropertyElements("4").Description: Item Timestamp
        //PropertyElements("1").Description: Item Canonical Data Type
        //PropertyElements("103").Description: Low EU
        //PropertyElements("15009").Description: Addable
        //PropertyElements("6").Description: Server Scan Rate
        //PropertyElements("15000").Description: Item ID
        //PropertyElements("3").Description: Item Quality
    }
}

# This example shows how to enumerate all properties of an OPC item. For each property, it displays its Id and description.

#requires -Version 5.1
using namespace OpcLabs.EasyOpc.OperationModel
using namespace OpcLabs.EasyOpc.DataAccess

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

# Instantiate the client object.
$client = New-Object EasyDAClient

try {
    $propertyElements = $client.BrowseProperties("OPCLabs.KitServer.2", "Simulation.Random")
}
catch [OpcException] {
    Write-Host "*** Failure: $($PSItem.Exception.GetBaseException().Message)"
    return
}

Foreach ($propertyElement in $propertyElements) {
    Write-Host "PropertyElements(`"$($propertyElement.PropertyId.NumericalValue)`").Description: $($propertyElement.Description)"
}


# Example output:
#
#PropertyElements("15008").Description: Visible
#PropertyElements("5").Description: Item Access Rights
#PropertyElements("2").Description: Item Value
#PropertyElements("7").Description: Item EU Type
#PropertyElements("15001").Description: Item Name
#PropertyElements("4").Description: Item Timestamp
#PropertyElements("1").Description: Item Canonical Data Type
#PropertyElements("103").Description: Low EU
#PropertyElements("15009").Description: Addable
#PropertyElements("6").Description: Server Scan Rate
#PropertyElements("15000").Description: Item ID
#PropertyElements("3").Description: Item Quality

# This example shows how to enumerate all properties of an OPC item. For each property, it displays its Id and
# description.

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

# Import .NET namespaces.
from OpcLabs.EasyOpc.DataAccess import *
from OpcLabs.EasyOpc.OperationModel import *


# Instantiate the client object.
client = EasyDAClient()

# Perform the operation.
try:
    propertyElements = IEasyDAClientExtension.BrowseProperties(client, '', 'OPCLabs.KitServer.2', 'Simulation.Random')
except OpcException as opcException:
    print('*** Failure: ' + opcException.GetBaseException().Message)
    exit()

# Display results.
for propertyElement in propertyElements:
    print('PropertyElements[', propertyElement.PropertyId.NumericalValue, '].Description: ', propertyElement.Description,
          sep='')

Object Pascal
PHP
Visual Basic (VB 6.0)
VBScript

// This example shows how to enumerate all properties of an OPC item. For each property, it displays its Id and description.

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.

$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.

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.

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

Reference

IEasyDAClientExtension Class
IEasyDAClientExtension Members

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