OPC Studio User's Guide and Reference
Reading just the value (OPC UA)
Concepts > OPC Data Client Concepts > OPC Data Client Development Models > Imperative Programming Model > Imperative Programming Model for OPC Data (Classic and UA) > Obtaining Information (OPC Data) > Reading Attributes of OPC UA Nodes > Reading just the value (OPC UA)
In This Topic

Some applications need the actual data value for further processing (e.g. for computations that need be performed on the values), i.e. the status code must be Good and a valid value must be provided by the server, otherwise it is considered an error.

A single node and attribute

For such usage, call the ReadValue method, passing it the same arguments as to the Read method. The method will read the attribute data, check if the status is Good, and you will receive back an Object holding the actual data value. If the status code is not Good, the method will throw a UAStatusCodeException.

One-time read:

.NET

// This example shows how to read value of a single node, and display it.
//
// 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;
using OpcLabs.EasyOpc.UA;
using OpcLabs.EasyOpc.UA.OperationModel;

namespace UADocExamples._EasyUAClient
{
    partial class ReadValue
    {
        public static void Overload1()
        {
            UAEndpointDescriptor endpointDescriptor =
                "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer";
            // or "http://opcua.demo-this.com:51211/UA/SampleServer" (currently not supported)
            // or "https://opcua.demo-this.com:51212/UA/SampleServer/"

            // Instantiate the client object.
            var client = new EasyUAClient();

            Console.WriteLine("Obtaining value of a node...");
            object value;
            try
            {
                value = client.ReadValue(endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10853");
            }
            catch (UAException uaException)
            {
                Console.WriteLine($"*** Failure: {uaException.GetBaseException().Message}");
                return;
            }

            // Display results
            Console.WriteLine($"value: {value}");
        }
    }
}
# This example shows how to read value of a single node, and display it.
#
# 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.

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

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

[UAEndpointDescriptor]$endpointDescriptor =
    "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
# or "http://opcua.demo-this.com:51211/UA/SampleServer" (currently not supported)
# or "https://opcua.demo-this.com:51212/UA/SampleServer/"

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

Write-Host "Obtaining value of a node..."
try {
    $value = $client.ReadValue($endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10853")
}
catch [UAException] {
    Write-Host "*** Failure: $($PSItem.Exception.GetBaseException().Message)"
    return
}

# Display results
Write-Host "value: $($value)"
' This example shows how to read value of a single node, and display it.
'
' 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.UA
Imports OpcLabs.EasyOpc.UA.OperationModel

Namespace _EasyUAClient
    Partial Friend Class ReadValue
        Public Shared Sub Overload1()

            ' Define which server we will work with.
            Dim endpointDescriptor As UAEndpointDescriptor =
                    "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
            ' or "http://opcua.demo-this.com:51211/UA/SampleServer" (currently not supported)
            ' or "https://opcua.demo-this.com:51212/UA/SampleServer/"

            ' Instantiate the client object
            Dim client = New EasyUAClient()

            ' Obtain value of a node
            Dim value As Object
            Try
                value = client.ReadValue(endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10853")
            Catch uaException As UAException
                Console.WriteLine("*** Failure: {0}", uaException.GetBaseException.Message)
                Exit Sub
            End Try

            ' Display results
            Console.WriteLine("value: {0}", value)
        End Sub
    End Class
End Namespace

COM

// This example shows how to read value of a single node, and display it.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
// 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.

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

namespace _EasyUAClient
{
    void ReadValue::Main()
    {
        // Initialize the COM library
        CoInitializeEx(NULL, COINIT_MULTITHREADED);
        {
            // Instantiate the client object
            _EasyUAClientPtr ClientPtr(__uuidof(EasyUAClient));

            // Perform the operation
            _variant_t value = ClientPtr->ReadValue(
                //L"http://opcua.demo-this.com:51211/UA/SampleServer", 
                L"opc.tcp://opcua.demo-this.com:51210/UA/SampleServer",
                L"nsu=http://test.org/UA/Data/ ;i=10853");
    
            // Display results
            _variant_t vString;
            vString.ChangeType(VT_BSTR, &value);
            _tprintf(_T("value: %s\n"), (LPCTSTR)CW2CT((_bstr_t)vString));
        }
         // Release all interface pointers BEFORE calling CoUninitialize()
        CoUninitialize();
    }
}
// This example shows how to read value of a single node, and display it.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
// 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.

var Client = new ActiveXObject("OpcLabs.EasyOpc.UA.EasyUAClient");
var value = Client.ReadValue(
    //"http://opcua.demo-this.com:51211/UA/SampleServer",
    "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer",
    "nsu=http://test.org/UA/Data/ ;i=10853");
WScript.Echo("value: " + value);
// This example shows how to read value of a single node, and display it.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
// 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 ReadValue.Main;
var
  Client: EasyUAClient;
  Value: OleVariant;
begin
  // Instantiate the client object
  Client := CoEasyUAClient.Create;

  Value := Client.ReadValue(
    //'http://opcua.demo-this.com:51211/UA/SampleServer',
    'opc.tcp://opcua.demo-this.com:51210/UA/SampleServer',
    'nsu=http://test.org/UA/Data/ ;i=10853');
  WriteLn('value: ', Value);
end;
// This example shows how to read value of a single node, and display it.
//
// 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 ReadValue.Main;
var
  Client: OpcLabs_EasyOpcUA_TLB._EasyUAClient;
  Value: OleVariant;
begin
  // Instantiate the client object
  Client := CoEasyUAClient.Create;

  // Obtain value of a node
  try
    Value := Client.ReadValue(
      //'http://opcua.demo-this.com:51211/UA/SampleServer',
      //'https://opcua.demo-this.com:51212/UA/SampleServer/',
      'opc.tcp://opcua.demo-this.com:51210/UA/SampleServer',
      'nsu=http://test.org/UA/Data/ ;i=10853');
  except
    on E: EOleException do
    begin
      WriteLn(Format('*** Failure: %s', [E.GetBaseException.Message]));
      Exit;
    end;
  end;

  // Display results
  WriteLn('value: ', Value);
end;
// This example shows how to read value of a single node, and display it.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
// OPC client and subscriber examples in PHP on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-PHP .
// 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.

// Instantiate the client object
$Client = new COM("OpcLabs.EasyOpc.UA.EasyUAClient");

// Perform the operation
try
{
    $value = $Client->ReadValue(
        //"http://opcua.demo-this.com:51211/UA/SampleServer", 
        "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer", 
        "nsu=http://test.org/UA/Data/ ;i=10853");
}
catch (com_exception $e)
{
    printf("*** Failure: %s\n", $e->getMessage());
    Exit();
}


// Display results
printf("Value: %s\n", $value);
// This example shows how to read value of a single node, and display it.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

mle_outputtext.Text = ""

// Instantiate the client object
OLEObject client
client = CREATE OLEObject
client.ConnectToNewObject("OpcLabs.EasyOpc.UA.EasyUAClient")

// Obtain value of a node
mle_outputtext.Text = mle_outputtext.Text + "Reading node value..." + "~r~n"
Any value
TRY
    value = client.ReadValue("http://opcua.demo-this.com:51211/UA/SampleServer", "nsu=http://test.org/UA/Data/ ;i=10853")
CATCH (OLERuntimeError oleRuntimeError)
    mle_outputtext.Text = mle_outputtext.Text + "*** Failure: " + oleRuntimeError.Description + "~r~n"
    RETURN
END TRY

// Display results
mle_outputtext.Text = mle_outputtext.Text + String(value) + "~r~n"
# This example shows how to read value of a single node, and display it.
#
# The Python for Windows (pywin32) extensions package is needed. Install it using "pip install pypiwin32".
# CAUTION: We now recommend using Python.NET package instead. Full set of examples with Python.NET is available!
#
# Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
import win32com.client
from pywintypes import com_error

# Instantiate the client object
client = win32com.client.Dispatch('OpcLabs.EasyOpc.UA.EasyUAClient') 

# Perform the operation
try:
    value = client.ReadValue('opc.tcp://opcua.demo-this.com:51210/UA/SampleServer', 'nsu=http://test.org/UA/Data/ ;i=10853')
except com_error as e:
    print('*** Failure: ' + e.args[2][1] + ': ' + e.args[2][2])
    exit()

# Display results
print('value: ', value)
REM This example shows how to read value of a single node, and display it.
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.

Public Sub ReadValue_Main_Command_Click()
    OutputText = ""

    ' Instantiate the client object
    Dim Client As New EasyUAClient

    ' Perform the operation
    On Error Resume Next
    Dim value As Variant
    value = Client.ReadValue("opc.tcp://opcua.demo-this.com:51210/UA/SampleServer", "nsu=http://test.org/UA/Data/ ;i=10853")
    If Err.Number <> 0 Then
        OutputText = OutputText & "*** Failure: " & Err.Source & ": " & Err.Description & vbCrLf
        Exit Sub
    End If
    On Error GoTo 0
    
    ' Display results
    OutputText = OutputText & "value: " & value & vbCrLf
End Sub
Rem This example shows how to read value of a single node, and display it.
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

' Instantiate the client object
Dim Client: Set Client = CreateObject("OpcLabs.EasyOpc.UA.EasyUAClient")

' Perform the operation
On Error Resume Next
Dim value: value = Client.ReadValue("opc.tcp://opcua.demo-this.com:51210/UA/SampleServer", "nsu=http://test.org/UA/Data/ ;i=10853")
If Err.Number <> 0 Then
    WScript.Echo "*** Failure: " & Err.Source & ": " & Err.Description
    WScript.Quit
End If
On Error Goto 0

' Display results
WScript.Echo "value: " & value

Python

# This example shows how to read value of a single node, and display it.
#
# 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 OpcLabs.EasyOpc.UA import *
from OpcLabs.EasyOpc.UA.OperationModel import *


endpointDescriptor = UAEndpointDescriptor('opc.tcp://opcua.demo-this.com:51210/UA/SampleServer')
# or 'http://opcua.demo-this.com:51211/UA/SampleServer' (currently not supported)
# or 'https://opcua.demo-this.com:51212/UA/SampleServer/'

# Instantiate the client object.
client = EasyUAClient()

# Perform the operation.
try:
    value = IEasyUAClientExtension.ReadValue(client,
                                             endpointDescriptor,
                                             UANodeDescriptor('nsu=http://test.org/UA/Data/ ;i=10853'))
except UAException as uaException:
    print('*** Failure: ' + uaException.GetBaseException().Message)
    exit()

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

print('Finished.')

Repeated read:

.NET

// This example shows how to repeatedly read value of a single node, and display it.
//
// 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;
using System.Threading;
using OpcLabs.EasyOpc.UA;
using OpcLabs.EasyOpc.UA.OperationModel;

namespace UADocExamples._EasyUAClient
{
    partial class ReadValue
    {
        public static void Repeated()
        {
            const string endpointDescriptorUrlString =
                "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer";
            // or "http://opcua.demo-this.com:51211/UA/SampleServer" (currently not supported)
            // or "https://opcua.demo-this.com:51212/UA/SampleServer/"
            const string nodeIdExpandedText = "nsu=http://test.org/UA/Data/ ;i=10221";
            // Example settings with Softing dataFEED OPC Suite:
            //  endpointDescriptorUrlString = "opc.tcp://localhost:4980/Softing_dataFEED_OPC_Suite_Configuration1";
            //  nodeIdExpandedText = "nsu=Local%20Items ;s=Local Items.EAK_Test1.EAK_Testwert1_I4";

            // Instantiate the client object.
            var client = new EasyUAClient();

            for (int i = 1; i <= 60; i++)
            {
                Console.Write($"@{DateTime.Now}: ");

                // Obtain value of a node
                object value;
                try
                {
                    value = client.ReadValue(endpointDescriptorUrlString, nodeIdExpandedText);
                }
                catch (UAException uaException)
                {
                    Console.WriteLine($"*** Failure: {uaException.GetBaseException().Message}");
                    return;
                }

                // Display results
                Console.WriteLine($"Read {value}");

                //
                Thread.Sleep(1000);
            }
        }
    }
}

COM

// This example shows how to repeatedly read value of a single node, and display it.
//
// 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 ReadValue.Repeated;
const
  EndpointDescriptorUrlString = 
    //'http://opcua.demo-this.com:51211/UA/SampleServer';
    //'https://opcua.demo-this.com:51212/UA/SampleServer/';
    'opc.tcp://opcua.demo-this.com:51210/UA/SampleServer';
  NodeIdExpandedText = 'nsu=http://test.org/UA/Data/ ;i=10221';
// Example settings with Softing dataFEED OPC Suite:
//  EndpointDescriptorUrlString = 'opc.tcp://localhost:4980/Softing_dataFEED_OPC_Suite_Configuration1';
//  NodeIdExpandedText = 'nsu=Local%20Items ;s=Local Items.EAK_Test1.EAK_Testwert1_I4';
var
  Client: OpcLabs_EasyOpcUA_TLB._EasyUAClient;
  Value: OleVariant;
  I: Integer;
begin
  // Instantiate the client object
  Client := CoEasyUAClient.Create;

  for I := 1 to 60 do
  begin
    Write('@', TimeToStr(Now), ': ');

    // Obtain value of a node
    try
      Value := Client.ReadValue(EndpointDescriptorUrlString, NodeIdExpandedText);
    except
      on E: EOleException do
        WriteLn(Format('*** Failure: %s', [E.GetBaseException.Message]));
    end;

    // Display results
    WriteLn('Read ', Value);

    //
    Sleep(1000);
  end;
end;

 

// This example shows how to read a value of a specific attribute of a single node, and display it.
//
// 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;
using OpcLabs.EasyOpc.UA;
using OpcLabs.EasyOpc.UA.OperationModel;

namespace UADocExamples._EasyUAClient
{
    partial class ReadValue
    {
        public static void Overload2()
        {
            UAEndpointDescriptor endpointDescriptor =
                "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer";
            // or "http://opcua.demo-this.com:51211/UA/SampleServer" (currently not supported)
            // or "https://opcua.demo-this.com:51212/UA/SampleServer/"

            UANodeDescriptor nodeDescriptor = "nsu=http://test.org/UA/Data/ ;i=10853";

            // Instantiate the client object
            var client = new EasyUAClient();

            // Obtain value of a DataType attribute
            object value;
            try
            {
                value = client.ReadValue(endpointDescriptor, nodeDescriptor, UAAttributeId.DataType);
            }
            catch (UAException uaException)
            {
                Console.WriteLine($"*** Failure: {uaException.GetBaseException().Message}");
                return;
            }

            // Display results
            Console.WriteLine($"value type: {value?.GetType()}");
            Console.WriteLine($"value: {value}");
        }
    }
}
# This example shows how to read a value of a specific attribute of a single node, and display it.
#
# 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.

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

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

[UAEndpointDescriptor]$endpointDescriptor =
    "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
# or "http://opcua.demo-this.com:51211/UA/SampleServer" (currently not supported)
# or "https://opcua.demo-this.com:51212/UA/SampleServer/"

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

# Obtain value of a DataType attribute
try {
    $value = [OpcLabs.EasyOpc.UA.IEasyUAClientExtension]::ReadValue($client,
        $endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10853",
        [OpcLabs.EasyOpc.UA.UAAttributeId]::DataType)
}
catch [UAException] {
    Write-Host "*** Failure: $($PSItem.Exception.GetBaseException().Message)"
    return
}

# Display results
Write-Host "value type: $($value.GetType())"
Write-Host "value: $($value)"
' This example shows how to read a value of a specific attribute of a single node, and display it.
'
' 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.UA
Imports OpcLabs.EasyOpc.UA.OperationModel

Namespace _EasyUAClient
    Partial Friend Class ReadValue
        Public Shared Sub Overload2()

            ' Define which server we will work with.
            Dim endpointDescriptor As UAEndpointDescriptor =
                    "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
            ' or "http://opcua.demo-this.com:51211/UA/SampleServer" (currently not supported)
            ' or "https://opcua.demo-this.com:51212/UA/SampleServer/"

            Dim nodeDescriptor As UANodeDescriptor = "nsu=http://test.org/UA/Data/ ;i=10853"

            ' Instantiate the client object.
            Dim client = New EasyUAClient()

            ' Obtain value of a DataType attribute.
            Dim value As Object
            Try
                value = client.ReadValue(endpointDescriptor, nodeDescriptor, UAAttributeId.DataType)
            Catch uaException As UAException
                Console.WriteLine("*** Failure: {0}", uaException.GetBaseException.Message)
                Exit Sub
            End Try

            ' Display results
            Console.WriteLine("value type: {0}", value.GetType())
            Console.WriteLine("value: {0}", value)
        End Sub
    End Class
End Namespace

Python

# This example shows how to read a value of a specific attribute of a single node, and display it.
#
# 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 OpcLabs.EasyOpc.UA import *
from OpcLabs.EasyOpc.UA.OperationModel import *


endpointDescriptor = UAEndpointDescriptor('opc.tcp://opcua.demo-this.com:51210/UA/SampleServer')
# or 'http://opcua.demo-this.com:51211/UA/SampleServer' (currently not supported)
# or 'https://opcua.demo-this.com:51212/UA/SampleServer/'

nodeDescriptor = UANodeDescriptor('nsu=http://test.org/UA/Data/ ;i=10853')

# Instantiate the client object.
client = EasyUAClient()

# Obtain value of a DataType attribute.
try:
    value = IEasyUAClientExtension.ReadValue(client, endpointDescriptor, nodeDescriptor, UAAttributeId.DataType)
except UAException as uaException:
    print('*** Failure: ' + uaException.GetBaseException().Message)
    exit()

# Display results.
print('value type: ', type(value), sep='')  # The output will differ from pure .NET languages such as C# or VB.NET.
print('value: ', value, sep='')

print()
print('Finished.')

 

Reading an array

.NET

// This example shows how to read a value from a single node that is an array of UInt16.
//
// 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;
using OpcLabs.EasyOpc.UA;
using OpcLabs.EasyOpc.UA.OperationModel;

namespace UADocExamples._EasyUAClient
{
    partial class ReadValue
    {
        public static void ArrayOfUInt16()
        {
            UAEndpointDescriptor endpointDescriptor =
                "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer";
            // or "http://opcua.demo-this.com:51211/UA/SampleServer" (currently not supported)
            // or "https://opcua.demo-this.com:51212/UA/SampleServer/"

            // Instantiate the client object
            var client = new EasyUAClient();

            Console.WriteLine("Obtaining value of a node...");
            int[] value;
            try
            {
                // UInt16 is returned as Int32, because UInt16 is not a CLS-compliant type (and is not supported in VB.NET).
                value = (int[])client.ReadValue(endpointDescriptor,
                    "nsu=http://test.org/UA/Data/ ;ns=2;i=10932");   // /Data.Dynamic.Array.UInt16Value
            }
            catch (UAException uaException)
            {
                Console.WriteLine($"*** Failure: {uaException.GetBaseException().Message}");
                return;
            }

            if (!(value is null))
            {
                Console.WriteLine(value[0]);
                Console.WriteLine(value[1]);
                Console.WriteLine(value[2]);
            }

            Console.WriteLine("Finished.");
        }
    }
}
' This example shows how to read a value from a single node that is an array of UInt16.
'
' 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.UA
Imports OpcLabs.EasyOpc.UA.OperationModel

Namespace _EasyUAClient
    Partial Friend Class ReadValue
        Public Shared Sub ArrayOfUInt16()

            ' Define which server we will work with.
            Dim endpointDescriptor As UAEndpointDescriptor =
                    "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
            ' or "http://opcua.demo-this.com:51211/UA/SampleServer" (currently not supported)
            ' or "https://opcua.demo-this.com:51212/UA/SampleServer/"

            ' Instantiate the client object
            Dim client = New EasyUAClient()

            Console.WriteLine("Obtaining value of a node...")
            Dim value As Int32()
            Try
                ' UInt16 is returned as Int32, because UInt16 is not a CLS-compliant type (and is not supported in VB.NET).
                ' // /Data.Dynamic.Array.UInt16Value
                value = CType(client.ReadValue(endpointDescriptor, "nsu=http://test.org/UA/Data/ ;ns=2;i=10932"), Int32())
            Catch uaException As UAException
                Console.WriteLine("*** Failure: {0}", uaException.GetBaseException.Message)
                Exit Sub
            End Try

            If Not IsNothing(value) Then
                Console.WriteLine(value(0))
                Console.WriteLine(value(1))
                Console.WriteLine(value(2))
            End If
        End Sub
    End Class
End Namespace

Python

# This example shows how to read a value from a single node that is an array of UInt16.
#
# 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 OpcLabs.EasyOpc.UA import *
from OpcLabs.EasyOpc.UA.OperationModel import *


# Instantiate the client object.
client = EasyUAClient()

print('Obtaining value of a node...')
try:
    # UInt16 is returned as Int32, because UInt16 is not a CLS-compliant type (and is not supported in VB.NET).
    value = IEasyUAClientExtension.ReadValue(client,
        UAEndpointDescriptor('opc.tcp://opcua.demo-this.com:51210/UA/SampleServer'),
        UANodeDescriptor('nsu=http://test.org/UA/Data/ ;ns=2;i=10932')) # /Data.Dynamic.Array.UInt16Value
except UAException as uaException:
    print('*** Failure: ' + uaException.GetBaseException().Message)
    exit()

# Display results.
if value is not None:
    print(value[0])
    print(value[1])
    print(value[2])

print()
print('Finished.')

 

Multiple nodes or attributes

For reading just the data values of multiple data values (with Good status) in an efficient manner, call the ReadMultipleValues method (instead of multiple ReadValue calls in a loop). You pass in an array of UAReadArguments objects, and you will receive back an array of ValueResult objects.

.NET

// This example shows how to read the Value attributes of 3 different nodes at once. Using the same method, it is also possible 
// to read multiple attributes of the same node.
//
// 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;
using OpcLabs.BaseLib.OperationModel;
using OpcLabs.EasyOpc.UA;
using OpcLabs.EasyOpc.UA.OperationModel;

namespace UADocExamples._EasyUAClient
{
    partial class ReadMultipleValues
    {
        public static void Main1()
        {
            UAEndpointDescriptor endpointDescriptor =
                "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer";
            // or "http://opcua.demo-this.com:51211/UA/SampleServer" (currently not supported)
            // or "https://opcua.demo-this.com:51212/UA/SampleServer/"

            // Instantiate the client object.
            var client = new EasyUAClient();

            // Obtain values. By default, the Value attributes of the nodes will be read.
            ValueResult[] valueResultArray = client.ReadMultipleValues(new[]
                {
                    new UAReadArguments(endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10845"),
                    new UAReadArguments(endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10853"),
                    new UAReadArguments(endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10855")
                });

            // Display results.
            foreach (ValueResult valueResult in valueResultArray)
            {
                if (valueResult.Succeeded)
                    Console.WriteLine($"Value: {valueResult.Value}");
                else
                    Console.WriteLine($"*** Failure: {valueResult.ErrorMessageBrief}");
            }


            // Example output:
            //
            //Value: 8
            //Value: -8.06803E+21
            //Value: Strawberry Pig Banana Snake Mango Purple Grape Monkey Purple? Blueberry Lemon^            
        }
    }
}
# This example shows how to read the Value attributes of 3 different nodes at once. Using the same method, it is also possible 
# to read multiple attributes of the same node.
#
# 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.

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

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

[UAEndpointDescriptor]$endpointDescriptor =
    "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
# or "http://opcua.demo-this.com:51211/UA/SampleServer" (currently not supported)
# or "https://opcua.demo-this.com:51212/UA/SampleServer/"

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

# Obtain values. By default, the Value attributes of the nodes will be read.
$valueResultArray = $client.ReadMultipleValues([UAReadArguments[]]@(
        (New-Object UAReadArguments($endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10845")), 
        (New-Object UAReadArguments($endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10853")), 
        (New-Object UAReadArguments($endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10855"))
    ))

foreach ($valueResult in $valueResultArray) {
    if ($valueResult.Succeeded) {
        Write-Host "Value: $($valueResult.Value)"
    }
    else {
        Write-Host "*** Failure: $($valueResult.ErrorMessageBrief)"
    }
}


# Example output:
#
#Value: 8
#Value: -8.06803E+21
#Value: Strawberry Pig Banana Snake Mango Purple Grape Monkey Purple? Blueberry Lemon^            

' This example shows how to read the Value attributes of 3 different nodes at once. Using the same method, it is also possible 
' to read multiple attributes of the same node.
'
' 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 System
Imports OpcLabs.BaseLib.OperationModel
Imports OpcLabs.EasyOpc.UA
Imports OpcLabs.EasyOpc.UA.OperationModel

Namespace _EasyUAClient
    Partial Friend Class ReadMultipleValues
        Public Shared Sub Main1()

            ' Define which server we will work with.
            Dim endpointDescriptor As UAEndpointDescriptor =
                    "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
            ' or "http://opcua.demo-this.com:51211/UA/SampleServer" (currently not supported)
            ' or "https://opcua.demo-this.com:51212/UA/SampleServer/"

            ' Instantiate the client object
            Dim client = New EasyUAClient()

            ' Obtain values. By default, the Value attributes of the nodes will be read.
            Dim valueResultArray() As ValueResult = client.ReadMultipleValues(New UAReadArguments() _
               {
                   New UAReadArguments(endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10845"),
                   New UAReadArguments(endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10853"),
                   New UAReadArguments(endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10855")
               }
            )

            ' Display results
            For Each valueResult As ValueResult In valueResultArray
                If valueResult.Succeeded Then
                    Console.WriteLine("Value: {0}", valueResult.Value)
                Else
                    Console.WriteLine("*** Failure: {0}", valueResult.ErrorMessageBrief)
                End If
            Next valueResult

            ' Example output:
            '
            'Value: 8
            'Value: -8.06803E+21
            'Value: Strawberry Pig Banana Snake Mango Purple Grape Monkey Purple? Blueberry Lemon^            
        End Sub
    End Class
End Namespace

COM

// This example shows how to read the Value attributes of 3 different nodes at once. Using the same method, it is also possible 
// to read multiple attributes of the same node.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
// 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.

#include "stdafx.h"    // Includes "QuickOpc.h", and other commonly used files
#include <atlsafe.h>
#include "ReadMultipleValues.h"

namespace _EasyUAClient
{
    void ReadMultipleValues::Main()
    {
        // Initialize the COM library
        CoInitializeEx(NULL, COINIT_MULTITHREADED);
        {
            // Instantiate the client object
            _EasyUAClientPtr ClientPtr(__uuidof(EasyUAClient));

            _UAReadArgumentsPtr ReadArguments1Ptr(_uuidof(UAReadArguments));
            ReadArguments1Ptr->EndpointDescriptor->UrlString = 
                //L"http://opcua.demo-this.com:51211/UA/SampleServer";
                L"opc.tcp://opcua.demo-this.com:51210/UA/SampleServer";
            ReadArguments1Ptr->NodeDescriptor->NodeId->ExpandedText = L"nsu=http://test.org/UA/Data/ ;i=10845";

            _UAReadArgumentsPtr ReadArguments2Ptr(_uuidof(UAReadArguments));
            ReadArguments2Ptr->EndpointDescriptor->UrlString = 
                //L"http://opcua.demo-this.com:51211/UA/SampleServer";
                L"opc.tcp://opcua.demo-this.com:51210/UA/SampleServer";
            ReadArguments2Ptr->NodeDescriptor->NodeId->ExpandedText = L"nsu=http://test.org/UA/Data/ ;i=10853";

            _UAReadArgumentsPtr ReadArguments3Ptr(_uuidof(UAReadArguments));
            ReadArguments3Ptr->EndpointDescriptor->UrlString = 
                //L"http://opcua.demo-this.com:51211/UA/SampleServer";
                L"opc.tcp://opcua.demo-this.com:51210/UA/SampleServer";
            ReadArguments3Ptr->NodeDescriptor->NodeId->ExpandedText = L"nsu=http://test.org/UA/Data/ ;i=10855";

            CComSafeArray<VARIANT> arguments(3);
            arguments.SetAt(0, _variant_t((IDispatch*)ReadArguments1Ptr));
            arguments.SetAt(1, _variant_t((IDispatch*)ReadArguments2Ptr));
            arguments.SetAt(2, _variant_t((IDispatch*)ReadArguments3Ptr));
            CComVariant vArguments(arguments);

            // Obtain values. By default, the Value attributes of the nodes will be read.
            CComSafeArray<VARIANT> results;
            results.Attach(ClientPtr->ReadMultipleValues(&vArguments));
            
            // Display results
            for (int i = results.GetLowerBound(); i <= results.GetUpperBound(); i++)
            {
                _ValueResultPtr ValueResultPtr = results[i];

                _variant_t vString;
                vString.ChangeType(VT_BSTR, &ValueResultPtr->Value);
                _tprintf(_T("Value: %s\n"), (LPCTSTR)CW2CT((_bstr_t)vString));
            }

            // Example output:
            //
            //Value: 8
            //Value: -8.06803E+21
            //Value: Strawberry Pig Banana Snake Mango Purple Grape Monkey Purple? Blueberry Lemon^            
        }
         // Release all interface pointers BEFORE calling CoUninitialize()
        CoUninitialize();
    }
}
// This example shows how to read the Value attributes of 3 different nodes at
// once. Using the same method, it is also possible to read multiple attributes
// of the same node.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
// 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 ReadMultipleValues.Main;
var
  Client: EasyUAClient;
  ReadArguments1, ReadArguments2, ReadArguments3: _UAReadArguments;
  Arguments, Results: OleVariant;
  I: Cardinal;
  Result: _ValueResult;
begin
  // Instantiate the client object
  Client := CoEasyUAClient.Create;

  ReadArguments1 := CoUAReadArguments.Create;
  ReadArguments1.EndpointDescriptor.UrlString := 
    //'http://opcua.demo-this.com:51211/UA/SampleServer';
    'opc.tcp://opcua.demo-this.com:51210/UA/SampleServer';
  ReadArguments1.NodeDescriptor.NodeId.ExpandedText := 'nsu=http://test.org/UA/Data/ ;i=10845';

  ReadArguments2 := CoUAReadArguments.Create;
  ReadArguments2.EndpointDescriptor.UrlString := 
    //'http://opcua.demo-this.com:51211/UA/SampleServer';
    'opc.tcp://opcua.demo-this.com:51210/UA/SampleServer';
  ReadArguments2.NodeDescriptor.NodeId.ExpandedText := 'nsu=http://test.org/UA/Data/ ;i=10853';

  ReadArguments3 := CoUAReadArguments.Create;
  ReadArguments3.EndpointDescriptor.UrlString := 
    //'http://opcua.demo-this.com:51211/UA/SampleServer';
    'opc.tcp://opcua.demo-this.com:51210/UA/SampleServer';
  ReadArguments3.NodeDescriptor.NodeId.ExpandedText := 'nsu=http://test.org/UA/Data/ ;i=10855';

  Arguments := VarArrayCreate([0, 2], varVariant);
  Arguments[0] := ReadArguments1;
  Arguments[1] := ReadArguments2;
  Arguments[2] := ReadArguments3;

  // Obtain values. By default, the Value attributes of the nodes will be read.
  TVarData(Results).VType := varArray or varVariant;
  TVarData(Results).VArray := PVarArray(Client.ReadMultipleValues(
    PSafeArray(TVarData(Arguments).VArray)));

  // Display results
  for I := VarArrayLowBound(Results, 1) to VarArrayHighBound(Results, 1) do
  begin
      Result := IInterface(Results[I]) as _ValueResult;
      WriteLn('Value: ', Result.Value);
  end;

  // Example output:
  //
  //Value: 8
  //Value: -8.06803E+21
  //Value: Strawberry Pig Banana Snake Mango Purple Grape Monkey Purple? Blueberry Lemon^
end;
// This example shows how to read the Value attributes of 3 different nodes at
// once. Using the same method, it is also possible to read multiple attributes
// of the same 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 ReadMultipleValues.Main;
var
  Client: OpcLabs_EasyOpcUA_TLB._EasyUAClient;
  ReadArguments1, ReadArguments2, ReadArguments3: _UAReadArguments;
  Arguments, Results: OleVariant;
  I: Cardinal;
  Result: _ValueResult;
begin
  // Instantiate the client object
  Client := CoEasyUAClient.Create;

  ReadArguments1 := CoUAReadArguments.Create;
  ReadArguments1.EndpointDescriptor.UrlString := 
    //'http://opcua.demo-this.com:51211/UA/SampleServer';
    //'https://opcua.demo-this.com:51212/UA/SampleServer/';
    'opc.tcp://opcua.demo-this.com:51210/UA/SampleServer';
  ReadArguments1.NodeDescriptor.NodeId.ExpandedText := 'nsu=http://test.org/UA/Data/ ;i=10845';

  ReadArguments2 := CoUAReadArguments.Create;
  ReadArguments2.EndpointDescriptor.UrlString := 
    //'http://opcua.demo-this.com:51211/UA/SampleServer';
    //'https://opcua.demo-this.com:51212/UA/SampleServer/';
    'opc.tcp://opcua.demo-this.com:51210/UA/SampleServer';
  ReadArguments2.NodeDescriptor.NodeId.ExpandedText := 'nsu=http://test.org/UA/Data/ ;i=10853';

  ReadArguments3 := CoUAReadArguments.Create;
  ReadArguments3.EndpointDescriptor.UrlString := 
    //'http://opcua.demo-this.com:51211/UA/SampleServer';
    //'https://opcua.demo-this.com:51212/UA/SampleServer/';
    'opc.tcp://opcua.demo-this.com:51210/UA/SampleServer';
  ReadArguments3.NodeDescriptor.NodeId.ExpandedText := 'nsu=http://test.org/UA/Data/ ;i=10855';

  Arguments := VarArrayCreate([0, 2], varVariant);
  Arguments[0] := ReadArguments1;
  Arguments[1] := ReadArguments2;
  Arguments[2] := ReadArguments3;

  // Obtain values. By default, the Value attributes of the nodes will be read.
  TVarData(Results).VType := varArray or varVariant;
  TVarData(Results).VArray := PVarArray(Client.ReadMultipleValues(Arguments));

  // Display results
  for I := VarArrayLowBound(Results, 1) to VarArrayHighBound(Results, 1) do
  begin
      Result := IInterface(Results[I]) as _ValueResult;
      if Result.Succeeded then
        WriteLn('Value: ', Result.Value)
      else
        WriteLn('results(', I, ') *** Failure: ', Result.ErrorMessageBrief);
  end;

  VarClear(Results);
  VarClear(Arguments);

  // Example output:
  //
  //Value: 8
  //Value: -8.06803E+21
  //Value: Strawberry Pig Banana Snake Mango Purple Grape Monkey Purple? Blueberry Lemon^
end;
// This example shows how to read the Value attributes of 3 different nodes at once. Using the same method, it is also possible 
// to read multiple attributes of the same node.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
// OPC client and subscriber examples in PHP on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-PHP .
// 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.

// Instantiate the client object
$Client = new COM("OpcLabs.EasyOpc.UA.EasyUAClient");

$ReadArguments1 = new COM("OpcLabs.EasyOpc.UA.OperationModel.UAReadArguments");
$ReadArguments1->EndpointDescriptor->UrlString = 
    //"http://opcua.demo-this.com:51211/UA/SampleServer";
    //"https://opcua.demo-this.com:51212/UA/SampleServer/";
    "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer";
$ReadArguments1->NodeDescriptor->NodeId->ExpandedText = "nsu=http://test.org/UA/Data/ ;i=10845";

$ReadArguments2 = new COM("OpcLabs.EasyOpc.UA.OperationModel.UAReadArguments");
$ReadArguments2->EndpointDescriptor->UrlString = "
    //"http://opcua.demo-this.com:51211/UA/SampleServer";
    //"https://opcua.demo-this.com:51212/UA/SampleServer/";
    "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer";
$ReadArguments2->NodeDescriptor->NodeId->ExpandedText = "nsu=http://test.org/UA/Data/ ;i=10853";

$ReadArguments3 = new COM("OpcLabs.EasyOpc.UA.OperationModel.UAReadArguments");
$ReadArguments3->EndpointDescriptor->UrlString = 
    //"http://opcua.demo-this.com:51211/UA/SampleServer";
    //"https://opcua.demo-this.com:51212/UA/SampleServer/";
    "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer";
$ReadArguments3->NodeDescriptor->NodeId->ExpandedText = "nsu=http://test.org/UA/Data/ ;i=10855";

$arguments[0] = $ReadArguments1;
$arguments[1] = $ReadArguments2;
$arguments[2] = $ReadArguments3;

// Obtain values. By default, the Value attributes of the nodes will be read.
$results = $Client->ReadMultipleValues($arguments);

// Display results
for ($i = 0; $i < count($results); $i++)
{
    $ValueResult = $results[$i];
    if ($ValueResult->Succeeded)
        printf("Value: %s\n", $ValueResult->Value);
    else
        printf("*** Failure: %s\n", $ValueResult->ErrorMessageBrief);
}

// Example output:
//
//Value: 8
//Value: -8.06803E+21
//Value: Strawberry Pig Banana Snake Mango Purple Grape Monkey Purple? Blueberry Lemon^            

// This example shows how to read the Value attributes of 3 different nodes at once. Using the same method, it is also possible 
// to read multiple attributes of the same node.

mle_outputtext.Text = ""

// Instantiate the client object
OLEObject client
client = CREATE OLEObject
client.ConnectToNewObject("OpcLabs.EasyOpc.UA.EasyUAClient")

// Prepare arguments. By default, the Value attributes of the nodes will be read.

OLEObject readArguments1
readArguments1 = CREATE OLEObject
readArguments1.ConnectToNewObject("OpcLabs.EasyOpc.UA.OperationModel.UAReadArguments")
readArguments1.EndpointDescriptor.UrlString = "http://opcua.demo-this.com:51211/UA/SampleServer"
readArguments1.NodeDescriptor.NodeId.ExpandedText = "nsu=http://test.org/UA/Data/ ;i=10845"

OLEObject readArguments2
readArguments2 = CREATE OLEObject
readArguments2.ConnectToNewObject("OpcLabs.EasyOpc.UA.OperationModel.UAReadArguments")
readArguments2.EndpointDescriptor.UrlString = "http://opcua.demo-this.com:51211/UA/SampleServer"
readArguments2.NodeDescriptor.NodeId.ExpandedText = "nsu=http://test.org/UA/Data/ ;i=10853"

OLEObject readArguments3
readArguments3 = CREATE OLEObject
readArguments3.ConnectToNewObject("OpcLabs.EasyOpc.UA.OperationModel.UAReadArguments")
readArguments3.EndpointDescriptor.UrlString = "http://opcua.demo-this.com:51211/UA/SampleServer"
readArguments3.NodeDescriptor.NodeId.ExpandedText = "nsu=http://test.org/UA/Data/ ;i=10855"

OLEObject readArgumentsList
readArgumentsList = CREATE OLEObject
readArgumentsList.ConnectToNewObject("OpcLabs.BaseLib.Collections.ElasticVector")
readArgumentsList.Add(readArguments1)
readArgumentsList.Add(readArguments2)
readArgumentsList.Add(readArguments3)

// Obtain values. 
OLEObject valueResultList
valueResultList = client.ReadValueList(readArgumentsList)

// Display results
Int i
FOR i = 0 TO valueResultList.Count - 1
    OLEObject valueResult
    valueResult = valueResultList.Item[i]
    IF valueResult.Succeeded THEN
        mle_outputtext.Text = mle_outputtext.Text + "Value: " + String(valueResult.Value) + "~r~n"
    ELSE
        mle_outputtext.Text = mle_outputtext.Text + "*** Failure: " + valueResult.ErrorMessageBrief + "~r~n"
    END IF    
NEXT

// Example output:
//
//Value: 8
//Value: -8.06803E+21
//Value: Strawberry Pig Banana Snake Mango Purple Grape Monkey Purple? Blueberry Lemon^            

REM This example shows how to read the Value attributes of 3 different nodes at once. Using the same method, it is also possible
REM to read multiple attributes of the same 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.

Public Sub ReadMultipleValues_Main_Command_Click()
    OutputText = ""

    ' Instantiate the client object
    Dim Client As New EasyUAClient

    Dim readArguments1 As New UAReadArguments
    readArguments1.endpointDescriptor.UrlString = "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
    readArguments1.nodeDescriptor.NodeId.expandedText = "nsu=http://test.org/UA/Data/ ;i=10845"

    Dim ReadArguments2 As New UAReadArguments
    ReadArguments2.endpointDescriptor.UrlString = "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
    ReadArguments2.nodeDescriptor.NodeId.expandedText = "nsu=http://test.org/UA/Data/ ;i=10853"

    Dim ReadArguments3 As New UAReadArguments
    ReadArguments3.endpointDescriptor.UrlString = "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
    ReadArguments3.nodeDescriptor.NodeId.expandedText = "nsu=http://test.org/UA/Data/ ;i=10855"

    Dim arguments(2) As Variant
    Set arguments(0) = readArguments1
    Set arguments(1) = ReadArguments2
    Set arguments(2) = ReadArguments3

    ' Obtain values. By default, the Value attributes of the nodes will be read.
    Dim results() As Variant
    results = Client.ReadMultipleValues(arguments)

    ' Display results
    Dim i: For i = LBound(results) To UBound(results)
        Dim Result As valueResult: Set Result = results(i)
        If Result.Succeeded Then
            OutputText = OutputText & "Value: " & Result.value & vbCrLf
        Else
            OutputText = OutputText & "*** Failure: " & Result.ErrorMessageBrief & vbCrLf
        End If
    Next

    ' Example output:
    '
    'Value: 8
    'Value: -8.06803E+21
    'Value: Strawberry Pig Banana Snake Mango Purple Grape Monkey Purple? Blueberry Lemon^
End Sub
Rem This example shows how to read the Value attributes of 3 different nodes at once. Using the same method, it is also possible 
Rem to read multiple attributes of the same 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

' Instantiate the client object
Dim Client: Set Client = CreateObject("OpcLabs.EasyOpc.UA.EasyUAClient")

Dim ReadArguments1: Set ReadArguments1 = CreateObject("OpcLabs.EasyOpc.UA.OperationModel.UAReadArguments")
ReadArguments1.EndpointDescriptor.UrlString = "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
ReadArguments1.NodeDescriptor.NodeId.ExpandedText = "nsu=http://test.org/UA/Data/ ;i=10845"

Dim ReadArguments2: Set ReadArguments2 = CreateObject("OpcLabs.EasyOpc.UA.OperationModel.UAReadArguments")
ReadArguments2.EndpointDescriptor.UrlString = "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
ReadArguments2.NodeDescriptor.NodeId.ExpandedText = "nsu=http://test.org/UA/Data/ ;i=10853"

Dim ReadArguments3: Set ReadArguments3 = CreateObject("OpcLabs.EasyOpc.UA.OperationModel.UAReadArguments")
ReadArguments3.EndpointDescriptor.UrlString = "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
ReadArguments3.NodeDescriptor.NodeId.ExpandedText = "nsu=http://test.org/UA/Data/ ;i=10855"

Dim arguments(2)
Set arguments(0) = ReadArguments1
Set arguments(1) = ReadArguments2
Set arguments(2) = ReadArguments3

' Obtain values. By default, the Value attributes of the nodes will be read.
Dim results: results = Client.ReadMultipleValues(arguments)

' Display results
Dim i: For i = LBound(results) To UBound(results)
    Dim ValueResult: Set ValueResult = results(i)
    If ValueResult.Succeeded Then
        WScript.Echo "Value: " & ValueResult.Value
    Else
        WScript.Echo "*** Failure: " & ValueResult.ErrorMessageBrief
    End If
Next

' Example output:
'
'Value: 8
'Value: -8.06803E+21
'Value: Strawberry Pig Banana Snake Mango Purple Grape Monkey Purple? Blueberry Lemon^            

Python

# This example shows how to read the Value attributes of 3 different nodes at once. Using the same method, it is also possible
# to read multiple attributes of the same node.
#
# 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 time

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


endpointDescriptor = UAEndpointDescriptor('opc.tcp://opcua.demo-this.com:51210/UA/SampleServer')
# or 'http://opcua.demo-this.com:51211/UA/SampleServer' (currently not supported)
# or 'https://opcua.demo-this.com:51212/UA/SampleServer/'

# Instantiate the client object.
client = EasyUAClient()

# Obtain values. By default, the Value attributes of the nodes will be read.
valueResultArray = IEasyUAClientExtension.ReadMultipleValues(client, [
    UAReadArguments(endpointDescriptor, UANodeDescriptor('nsu=http://test.org/UA/Data/ ;i=10845')),
    UAReadArguments(endpointDescriptor, UANodeDescriptor('nsu=http://test.org/UA/Data/ ;i=10853')),
    UAReadArguments(endpointDescriptor, UANodeDescriptor('nsu=http://test.org/UA/Data/ ;i=10855')),
    ])

# Display results.
for valueResult in valueResultArray:
    if valueResult.Succeeded:
        print('Value: ', valueResult.Value, sep='')
    else:
        print('*** Failure: ', valueResult.ErrorMessageBrief, sep='')

print()
print('Finished.')

 

Reading DataType attributes 

.NET

// This example shows how to read the DataType attributes of 3 different nodes at once. Using the same method, it is also possible 
// to read multiple attributes of the same node.
//
// 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;
using OpcLabs.BaseLib.OperationModel;
using OpcLabs.EasyOpc.UA;
using OpcLabs.EasyOpc.UA.AddressSpace;
using OpcLabs.EasyOpc.UA.OperationModel;

namespace UADocExamples._EasyUAClient
{
    partial class ReadMultipleValues
    {
        public static void DataType()
        {
            UAEndpointDescriptor endpointDescriptor =
                "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer";
            // or "http://opcua.demo-this.com:51211/UA/SampleServer" (currently not supported)
            // or "https://opcua.demo-this.com:51212/UA/SampleServer/"

            // Instantiate the client object.
            var client = new EasyUAClient();

            // Obtain values.
            ValueResult[] valueResultArray = client.ReadMultipleValues(new[]
                {
                    new UAReadArguments(endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10845", UAAttributeId.DataType),
                    new UAReadArguments(endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10853", UAAttributeId.DataType),
                    new UAReadArguments(endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10855", UAAttributeId.DataType)
                });

            // Display results.
            foreach (ValueResult valueResult in valueResultArray)
            {
                Console.WriteLine();

                if (valueResult.Succeeded)
                {
                    Console.WriteLine($"Value: {valueResult.Value}");
                    var dataTypeId = valueResult.Value as UANodeId;
                    if (!(dataTypeId is null))
                    {
                        Console.WriteLine($"Value.ExpandedText: {dataTypeId.ExpandedText}");
                        Console.WriteLine($"Value.NamespaceUriString: {dataTypeId.NamespaceUriString}");
                        Console.WriteLine($"Value.NamespaceIndex: {dataTypeId.NamespaceIndex}");
                        Console.WriteLine($"Value.NumericIdentifier: {dataTypeId.NumericIdentifier}");
                    }
                }
                else
                    Console.WriteLine($"*** Failure: {valueResult.ErrorMessageBrief}");
            }

            // Example output:
            //
            //Value: SByte
            //Value.ExpandedText: nsu=http://opcfoundation.org/UA/ ;i=2
            //Value.NamespaceUriString: http://opcfoundation.org/UA/
            //Value.NamespaceIndex: 0
            //Value.NumericIdentifier: 2
            //
            //Value: Float
            //Value.ExpandedText: nsu=http://opcfoundation.org/UA/ ;i=10
            //Value.NamespaceUriString: http://opcfoundation.org/UA/
            //Value.NamespaceIndex: 0
            //Value.NumericIdentifier: 10
            //
            //Value: String
            //Value.ExpandedText: nsu=http://opcfoundation.org/UA/ ;i=12
            //Value.NamespaceUriString: http://opcfoundation.org/UA/
            //Value.NamespaceIndex: 0
            //Value.NumericIdentifier: 12
        }
    }
}
# This example shows how to read the DataType attributes of 3 different nodes at once. Using the same method, it is also possible 
# to read multiple attributes of the same node.
#
# 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.

#requires -Version 5.1
using namespace OpcLabs.EasyOpc.UA
using namespace OpcLabs.EasyOpc.UA.AddressSpace
using namespace OpcLabs.EasyOpc.UA.OperationModel

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

[UAEndpointDescriptor]$endpointDescriptor =
    "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
# or "http://opcua.demo-this.com:51211/UA/SampleServer" (currently not supported)
# or "https://opcua.demo-this.com:51212/UA/SampleServer/"

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

# Obtain values. 
$valueResultArray = $client.ReadMultipleValues([UAReadArguments[]]@(
        (New-Object UAReadArguments($endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10845", [UAAttributeId]::DataType)), 
        (New-Object UAReadArguments($endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10853", [UAAttributeId]::DataType)), 
        (New-Object UAReadArguments($endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10855", [UAAttributeId]::DataType))
    ))

foreach ($valueResult in $valueResultArray) {
    Write-Host

    if ($valueResult.Succeeded) {
        Write-Host "Value: $($valueResult.Value)"
        [UANodeId]$dataTypeId = $valueResult.Value;
        if ($dataTypeId -ne $null) {
            Write-Host "Value.ExpandedText: $($dataTypeId.ExpandedText)"
            Write-Host "Value.NamespaceUriString: $($dataTypeId.NamespaceUriString)"
            Write-Host "Value.NamespaceIndex: $($dataTypeId.NamespaceIndex)"
            Write-Host "Value.NumericIdentifier: $($dataTypeId.NumericIdentifier)"
        }
    }
    else {
        Write-Host "*** Failure: $($valueResult.ErrorMessageBrief)"
    }
}


# Example output:
#
#Value: SByte
#Value.ExpandedText: nsu=http://opcfoundation.org/UA/ ;i=2
#Value.NamespaceUriString: http://opcfoundation.org/UA/
#Value.NamespaceIndex: 0
#Value.NumericIdentifier: 2
#
#Value: Float
#Value.ExpandedText: nsu=http://opcfoundation.org/UA/ ;i=10
#Value.NamespaceUriString: http://opcfoundation.org/UA/
#Value.NamespaceIndex: 0
#Value.NumericIdentifier: 10
#
#Value: String
#Value.ExpandedText: nsu=http://opcfoundation.org/UA/ ;i=12
#Value.NamespaceUriString: http://opcfoundation.org/UA/
#Value.NamespaceIndex: 0
#Value.NumericIdentifier: 12

' This example shows how to read the DataType attributes of 3 different nodes at once. Using the same method, it is also possible 
' to read multiple attributes of the same node.
'
' 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 System
Imports OpcLabs.BaseLib.OperationModel
Imports OpcLabs.EasyOpc.UA
Imports OpcLabs.EasyOpc.UA.AddressSpace
Imports OpcLabs.EasyOpc.UA.OperationModel

Namespace _EasyUAClient
    Partial Friend Class ReadMultipleValues
        Public Shared Sub DataType()

            ' Define which server we will work with.
            Dim endpointDescriptor As UAEndpointDescriptor =
                    "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
            ' or "http://opcua.demo-this.com:51211/UA/SampleServer" (currently not supported)
            ' or "https://opcua.demo-this.com:51212/UA/SampleServer/"

            ' Instantiate the client object
            Dim client = New EasyUAClient()

            ' Obtain values.
            Dim valueResultArray() As ValueResult = client.ReadMultipleValues(New UAReadArguments() _
               {
                   New UAReadArguments(endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10845", UAAttributeId.DataType),
                   New UAReadArguments(endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10853", UAAttributeId.DataType),
                   New UAReadArguments(endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10855", UAAttributeId.DataType)
               }
            )

            ' Display results
            For Each valueResult As ValueResult In valueResultArray
                Console.WriteLine()

                If valueResult.Succeeded Then
                    Console.WriteLine("Value: {0}", valueResult.Value)
                    Dim dataTypeId = CType(valueResult.Value, UANodeId)
                    If Not dataTypeId Is Nothing Then
                        Console.WriteLine("Value.ExpandedText: {0}", dataTypeId.ExpandedText)
                        Console.WriteLine("Value.NamespaceUriString: {0}", dataTypeId.NamespaceUriString)
                        Console.WriteLine("Value.NamespaceIndex: {0}", dataTypeId.NamespaceIndex)
                        Console.WriteLine("Value.NumericIdentifier: {0}", dataTypeId.NumericIdentifier)
                    End If
                Else
                    Console.WriteLine("*** Failure: {0}", valueResult.ErrorMessageBrief)
                End If
            Next valueResult

            ' Example output:
            '
            'Value: SByte
            'Value.ExpandedText: nsu = http : //opcfoundation.org/UA/ ;i=2
            'Value.NamespaceUriString: http : //opcfoundation.org/UA/
            'Value.NamespaceIndex: 0
            'Value.NumericIdentifier: 2
            '
            'Value: Float
            'Value.ExpandedText: nsu = http : //opcfoundation.org/UA/ ;i=10
            'Value.NamespaceUriString: http : //opcfoundation.org/UA/
            'Value.NamespaceIndex: 0
            'Value.NumericIdentifier: 10
            '
            'Value: String
            'Value.ExpandedText: nsu = http : //opcfoundation.org/UA/ ;i=12
            'Value.NamespaceUriString: http : //opcfoundation.org/UA/
            'Value.NamespaceIndex: 0
            'Value.NumericIdentifier: 12
        End Sub
    End Class
End Namespace

COM

// This example shows how to read the DataType attributes of 3 different nodes at
// once. Using the same method, it is also possible to read multiple attributes
// of the same 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 ReadMultipleValues.DataType;
var
  Client: OpcLabs_EasyOpcUA_TLB._EasyUAClient;
  ReadArguments1, ReadArguments2, ReadArguments3: _UAReadArguments;
  Arguments, Results: OleVariant;
  I: Cardinal;
  Result: _ValueResult;
begin
  // Instantiate the client object
  Client := CoEasyUAClient.Create;

  ReadArguments1 := CoUAReadArguments.Create;
  ReadArguments1.EndpointDescriptor.UrlString := 
    //'http://opcua.demo-this.com:51211/UA/SampleServer';
    //'https://opcua.demo-this.com:51212/UA/SampleServer/';
    'opc.tcp://opcua.demo-this.com:51210/UA/SampleServer';
  ReadArguments1.NodeDescriptor.NodeId.ExpandedText := 'nsu=http://test.org/UA/Data/ ;i=10845';
  ReadArguments1.AttributeId := UAAttributeId_DataType;

  ReadArguments2 := CoUAReadArguments.Create;
  ReadArguments2.EndpointDescriptor.UrlString := 
    //'http://opcua.demo-this.com:51211/UA/SampleServer';
    //'https://opcua.demo-this.com:51212/UA/SampleServer/';
    'opc.tcp://opcua.demo-this.com:51210/UA/SampleServer';
  ReadArguments2.NodeDescriptor.NodeId.ExpandedText := 'nsu=http://test.org/UA/Data/ ;i=10853';
  ReadArguments2.AttributeId := UAAttributeId_DataType;

  ReadArguments3 := CoUAReadArguments.Create;
  ReadArguments3.EndpointDescriptor.UrlString := 
    //'http://opcua.demo-this.com:51211/UA/SampleServer';
    //'https://opcua.demo-this.com:51212/UA/SampleServer/';
    'opc.tcp://opcua.demo-this.com:51210/UA/SampleServer';
  ReadArguments3.NodeDescriptor.NodeId.ExpandedText := 'nsu=http://test.org/UA/Data/ ;i=10855';
  ReadArguments3.AttributeId := UAAttributeId_DataType;

  Arguments := VarArrayCreate([0, 2], varVariant);
  Arguments[0] := ReadArguments1;
  Arguments[1] := ReadArguments2;
  Arguments[2] := ReadArguments3;

  // Obtain values. By default, the Value attributes of the nodes will be read.
  TVarData(Results).VType := varArray or varVariant;
  TVarData(Results).VArray := PVarArray(Client.ReadMultipleValues(Arguments));

  // Display results
  for I := VarArrayLowBound(Results, 1) to VarArrayHighBound(Results, 1) do
  begin
      Result := IInterface(Results[I]) as _ValueResult;
      WriteLn;
      if Result.Succeeded then
      begin
          WriteLn('Value: ', Result.Value);
          WriteLn('Value.ExpandedText: ', Result.Value.ExpandedText);
          WriteLn('Value.NamespaceUriString: ', Result.Value.NamespaceUriString);
          WriteLn('Value.NamespaceIndex: ', Result.Value.NamespaceIndex);
          WriteLn('Value.NumericIdentifier: ', Result.Value.NumericIdentifier);
      end
      else
        WriteLn('results(', I, ') *** Failure: ', Result.ErrorMessageBrief);
  end;
  
  VarClear(Results);
  VarClear(Arguments);

  // Example output:
  //
  //
  //Value: SByte
  //Value.ExpandedText: nsu=http://opcfoundation.org/UA/;i=2
  //Value.NamespaceUriString: http://opcfoundation.org/UA/
  //Value.NamespaceIndex: 0
  //Value.NumericIdentifier: 2
  //
  //Value: Float
  //Value.ExpandedText: nsu=http://opcfoundation.org/UA/;i=10
  //Value.NamespaceUriString: http://opcfoundation.org/UA/
  //Value.NamespaceIndex: 0
  //Value.NumericIdentifier: 10
  //
  //Value: String
  //Value.ExpandedText: nsu=http://opcfoundation.org/UA/;i=12
  //Value.NamespaceUriString: http://opcfoundation.org/UA/
  //Value.NamespaceIndex: 0
  //Value.NumericIdentifier: 12
end;
// This example shows how to read the DataType attributes of 3 different nodes at
// once. Using the same method, it is also possible to read multiple attributes
// of the same node.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
// OPC client and subscriber examples in PHP on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-PHP .
// 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.

const UAAttributeId_DataType = 14;

// Instantiate the client object
$Client = new COM("OpcLabs.EasyOpc.UA.EasyUAClient");

$ReadArguments1 = new COM("OpcLabs.EasyOpc.UA.OperationModel.UAReadArguments");
$ReadArguments1->EndpointDescriptor->UrlString = 
    //"http://opcua.demo-this.com:51211/UA/SampleServer";
    //"https://opcua.demo-this.com:51212/UA/SampleServer/";
    "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer";
$ReadArguments1->NodeDescriptor->NodeId->ExpandedText = "nsu=http://test.org/UA/Data/ ;i=10845";
$ReadArguments1->AttributeId = UAAttributeId_DataType;

$ReadArguments2 = new COM("OpcLabs.EasyOpc.UA.OperationModel.UAReadArguments");
$ReadArguments2->EndpointDescriptor->UrlString = 
    //"http://opcua.demo-this.com:51211/UA/SampleServer";
    //"https://opcua.demo-this.com:51212/UA/SampleServer/";
    "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer";
$ReadArguments2->NodeDescriptor->NodeId->ExpandedText = "nsu=http://test.org/UA/Data/ ;i=10853";
$ReadArguments2->AttributeId = UAAttributeId_DataType;

$ReadArguments3 = new COM("OpcLabs.EasyOpc.UA.OperationModel.UAReadArguments");
$ReadArguments3->EndpointDescriptor->UrlString = 
    //"http://opcua.demo-this.com:51211/UA/SampleServer";
    //"https://opcua.demo-this.com:51212/UA/SampleServer/";
    "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer";
$ReadArguments3->NodeDescriptor->NodeId->ExpandedText = "nsu=http://test.org/UA/Data/ ;i=10855";
$ReadArguments3->AttributeId = UAAttributeId_DataType;

$arguments[0] = $ReadArguments1;
$arguments[1] = $ReadArguments2;
$arguments[2] = $ReadArguments3;

// Obtain values. By default, the Value attributes of the nodes will be read.
$results = $Client->ReadMultipleValues($arguments);

// Display results
for ($i = 0; $i < count($results); $i++)
{
    $ValueResult = $results[$i];
    printf("\n");
    if ($ValueResult->Succeeded)
    {
        printf("Value: %s\n", $ValueResult->Value);
        printf("Value.ExpandedText: %s\n", $ValueResult->Value->ExpandedText);
        printf("Value.NamespaceUriString: %s\n", $ValueResult->Value->NamespaceUriString);
        printf("Value.NamespaceIndex: %s\n", $ValueResult->Value->NamespaceIndex);
        printf("Value.NumericIdentifier: %s\n", $ValueResult->Value->NumericIdentifier);
    }
    else
        printf("*** Failure: %s\n", $ValueResult->ErrorMessageBrief);
}

// Example output:
//
//
//Value: SByte
//Value.ExpandedText: nsu=http://opcfoundation.org/UA/;i=2
//Value.NamespaceUriString: http://opcfoundation.org/UA/
//Value.NamespaceIndex: 0
//Value.NumericIdentifier: 2
//
//Value: Float
//Value.ExpandedText: nsu=http://opcfoundation.org/UA/;i=10
//Value.NamespaceUriString: http://opcfoundation.org/UA/
//Value.NamespaceIndex: 0
//Value.NumericIdentifier: 10
//
//Value: String
//Value.ExpandedText: nsu=http://opcfoundation.org/UA/;i=12
//Value.NamespaceUriString: http://opcfoundation.org/UA/
//Value.NamespaceIndex: 0
//Value.NumericIdentifier: 12

REM This example shows how to read the DataType attributes of 3 different nodes at once. Using the same method, it is also possible
REM to read multiple attributes of the same 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.

Public Sub ReadMultipleValues_DataType_Command_Click()
    OutputText = ""
    
    ' Instantiate the client object
    Dim Client As New EasyUAClient

    Dim readArguments1 As New UAReadArguments
    readArguments1.endpointDescriptor.UrlString = "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
    readArguments1.nodeDescriptor.NodeId.expandedText = "nsu=http://test.org/UA/Data/ ;i=10845"
    readArguments1.AttributeId = UAAttributeId_DataType

    Dim ReadArguments2 As New UAReadArguments
    ReadArguments2.endpointDescriptor.UrlString = "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
    ReadArguments2.nodeDescriptor.NodeId.expandedText = "nsu=http://test.org/UA/Data/ ;i=10853"
    ReadArguments2.AttributeId = UAAttributeId_DataType

    Dim ReadArguments3 As New UAReadArguments
    ReadArguments3.endpointDescriptor.UrlString = "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
    ReadArguments3.nodeDescriptor.NodeId.expandedText = "nsu=http://test.org/UA/Data/ ;i=10855"
    ReadArguments3.AttributeId = UAAttributeId_DataType

    Dim arguments(2) As Variant
    Set arguments(0) = readArguments1
    Set arguments(1) = ReadArguments2
    Set arguments(2) = ReadArguments3

    ' Obtain values.
    Dim results() As Variant
    results = Client.ReadMultipleValues(arguments)

    ' Display results
    Dim i: For i = LBound(results) To UBound(results)
        OutputText = OutputText & vbCrLf
        
        Dim Result As valueResult: Set Result = results(i)
        If Result.Succeeded Then
            OutputText = OutputText & "Value: " & Result.value & vbCrLf
            On Error Resume Next
            OutputText = OutputText & "Value.ExpandedText: " & Result.value.expandedText & vbCrLf
            OutputText = OutputText & "Value.NamespaceUriString: " & Result.value.NamespaceUriString & vbCrLf
            OutputText = OutputText & "Value.NamespaceIndex: " & Result.value.NamespaceIndex & vbCrLf
            OutputText = OutputText & "Value.NumericIdentifier: " & Result.value.NumericIdentifier & vbCrLf
            On Error GoTo 0
        Else
            OutputText = OutputText & "*** Failure: " & Result.ErrorMessageBrief & vbCrLf
        End If
    Next

    ' Example output:
    '
    'Value: SByte
    'Value.ExpandedText: nsu=http://opcfoundation.org/UA/ ;i=2
    'Value.NamespaceUriString: http://opcfoundation.org/UA/
    'Value.NamespaceIndex: 0
    'Value.NumericIdentifier: 2
    '
    'Value: Float
    'Value.ExpandedText: nsu=http://opcfoundation.org/UA/ ;i=10
    'Value.NamespaceUriString: http://opcfoundation.org/UA/
    'Value.NamespaceIndex: 0
    'Value.NumericIdentifier: 10
    '
    'Value: String
    'Value.ExpandedText: nsu=http://opcfoundation.org/UA/ ;i=12
    'Value.NamespaceUriString: http://opcfoundation.org/UA/
    'Value.NamespaceIndex: 0
    'Value.NumericIdentifier: 12
End Sub
Rem This example shows how to read the DataType attributes of 3 different nodes at once. Using the same method, it is also possible 
Rem to read multiple attributes of the same 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 UAAttributeId_DataType = 14

' Instantiate the client object
Dim Client: Set Client = CreateObject("OpcLabs.EasyOpc.UA.EasyUAClient")

Dim ReadArguments1: Set ReadArguments1 = CreateObject("OpcLabs.EasyOpc.UA.OperationModel.UAReadArguments")
ReadArguments1.EndpointDescriptor.UrlString = "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
ReadArguments1.NodeDescriptor.NodeId.ExpandedText = "nsu=http://test.org/UA/Data/ ;i=10845"
ReadArguments1.AttributeId = UAAttributeId_DataType

Dim ReadArguments2: Set ReadArguments2 = CreateObject("OpcLabs.EasyOpc.UA.OperationModel.UAReadArguments")
ReadArguments2.EndpointDescriptor.UrlString = "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
ReadArguments2.NodeDescriptor.NodeId.ExpandedText = "nsu=http://test.org/UA/Data/ ;i=10853"
ReadArguments2.AttributeId = UAAttributeId_DataType

Dim ReadArguments3: Set ReadArguments3 = CreateObject("OpcLabs.EasyOpc.UA.OperationModel.UAReadArguments")
ReadArguments3.EndpointDescriptor.UrlString = "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
ReadArguments3.NodeDescriptor.NodeId.ExpandedText = "nsu=http://test.org/UA/Data/ ;i=10855"
ReadArguments3.AttributeId = UAAttributeId_DataType

Dim arguments(2)
Set arguments(0) = ReadArguments1
Set arguments(1) = ReadArguments2
Set arguments(2) = ReadArguments3

' Obtain values.
Dim results: results = Client.ReadMultipleValues(arguments)

' Display results
Dim i: For i = LBound(results) To UBound(results)
    WScript.Echo

    Dim ValueResult: Set ValueResult = results(i)
    If ValueResult.Succeeded Then
        WScript.Echo "Value: " & ValueResult.Value
        On Error Resume Next
        WScript.Echo "Value.ExpandedText: " & ValueResult.Value.ExpandedText
        WScript.Echo "Value.NamespaceUriString: " & ValueResult.Value.NamespaceUriString
        WScript.Echo "Value.NamespaceIndex: " & ValueResult.Value.NamespaceIndex
        WScript.Echo "Value.NumericIdentifier: " & ValueResult.Value.NumericIdentifier
        On Error Goto 0
    Else
        WScript.Echo "*** Failure: " & ValueResult.ErrorMessageBrief
    End If
Next

' Example output:
'
'Value: SByte
'Value.ExpandedText: nsu=http://opcfoundation.org/UA/ ;i=2
'Value.NamespaceUriString: http://opcfoundation.org/UA/
'Value.NamespaceIndex: 0
'Value.NumericIdentifier: 2
'
'Value: Float
'Value.ExpandedText: nsu=http://opcfoundation.org/UA/ ;i=10
'Value.NamespaceUriString: http://opcfoundation.org/UA/
'Value.NamespaceIndex: 0
'Value.NumericIdentifier: 10
'
'Value: String
'Value.ExpandedText: nsu=http://opcfoundation.org/UA/ ;i=12
'Value.NamespaceUriString: http://opcfoundation.org/UA/
'Value.NamespaceIndex: 0
'Value.NumericIdentifier: 12

Python

# This example shows how to read the DataType attributes of 3 different nodes at once. Using the same method, it is also
# possible to read multiple attributes of the same node.
#
# 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 time

# Import .NET namespaces.
from OpcLabs.EasyOpc.UA import *
from OpcLabs.EasyOpc.UA.AddressSpace import *
from OpcLabs.EasyOpc.UA.OperationModel import *


endpointDescriptor = UAEndpointDescriptor('opc.tcp://opcua.demo-this.com:51210/UA/SampleServer')
# or 'http://opcua.demo-this.com:51211/UA/SampleServer' (currently not supported)
# or 'https://opcua.demo-this.com:51212/UA/SampleServer/'

# Instantiate the client object.
client = EasyUAClient()

# Obtain values. By default, the Value attributes of the nodes will be read.
valueResultArray = IEasyUAClientExtension.ReadMultipleValues(client, [
    UAReadArguments(endpointDescriptor, UANodeDescriptor('nsu=http://test.org/UA/Data/ ;i=10845'),
                    UAAttributeId.DataType),
    UAReadArguments(endpointDescriptor, UANodeDescriptor('nsu=http://test.org/UA/Data/ ;i=10853'),
                    UAAttributeId.DataType),
    UAReadArguments(endpointDescriptor, UANodeDescriptor('nsu=http://test.org/UA/Data/ ;i=10855'),
                    UAAttributeId.DataType),
    ])

# Display results.
for valueResult in valueResultArray:
    print()
    #
    if valueResult.Succeeded:
        print('Value: ', valueResult.Value, sep='')
        if isinstance(valueResult.Value, UANodeId):
            dataTypeId = valueResult.Value
            print('dataTypeId.ExpandedText: ', dataTypeId.ExpandedText, sep='')
            print('dataTypeId.NamespaceUriString: ', dataTypeId.NamespaceUriString, sep='')
            print('dataTypeId.NamespaceIndex: ', dataTypeId.NamespaceIndex, sep='')
            print('dataTypeId.NumericIdentifier: ', dataTypeId.NumericIdentifier, sep='')
    else:
        print('*** Failure: ', valueResult.ErrorMessageBrief, sep='')

print()
print('Finished.')

Read Parameters

It is possible to specify read parameters, such as the maximum value age, or that the read should be performed from the cache, or directly from the device (data source). For more information, see Reading Attributes of OPC UA Nodes.

Advanced

If you access some node or nodes repeatedly, it might be possible to improve the performance of it by (pre-)registering the node or nodes with the server. The performance improvement will only occur if the target OPC UA server supports the necessary node registration services. For more information, see OPC UA Node Registration Service.

See Also

Knowledge Base

Installed Examples - Client Web

Examples - Client OPC Data Access

Examples - Client OPC Unified Architecture

Installed Examples - Client Windows Forms

Installed Examples - Client WPF