WriteValue Method (_EasyUAClient)

Writes value into a Value attribute of a node, using an endpoint descriptor and a node Id.

Syntax

Visual Basic
C#
C++/CLI

'Declaration
 
Sub WriteValue( _
   ByVal endpointDescriptorString As String, _
   ByVal nodeDescriptorString As String, _
   ByVal value As Object _
)

'Usage
 
Dim instance As _EasyUAClient
Dim endpointDescriptorString As String
Dim nodeDescriptorString As String
Dim value As Object
 
instance.WriteValue(endpointDescriptorString, nodeDescriptorString, value)

void WriteValue( 
   string endpointDescriptorString,
   string nodeDescriptorString,
   object value
)

void WriteValue( 
   String^ endpointDescriptorString,
   String^ nodeDescriptorString,
   Object^ value
)

Parameters

endpointDescriptorString: Endpoint descriptor. Identifies the OPC-UA server.
nodeDescriptorString: Node descriptor. Identifies the node in OPC server's address space.
value: The value to be written.

Remarks

You can obtain nodeDescriptorString e.g. by calling one of the browsing methods on OpcLabs.EasyOpc.UA.EasyUAClientCore object.

The component will determine the type of the Value attribute from the DataType and ValueRank attributes of the node first. This can have negative implication on the performance, and introduces a dependency of the value written on the behavior of the OPC server itself. Use a method overload that allows to specify the attribute type or type code to prevent this.

Example

// This example shows how to write a value into a single node.

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

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

            // Perform the operation
            ClientPtr->WriteValue(
                //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=10221",
                12345);
        }
         // Release all interface pointers BEFORE calling CoUninitialize()
        CoUninitialize();
    }
}

// This example shows how to write a value into a single node.

class procedure WriteValue.Main;
var
  Client: EasyUAClient;
begin
  // Instantiate the client object
  Client := CoEasyUAClient.Create;

  // Perform the operation
  Client.WriteValue(
    //'http://opcua.demo-this.com:51211/UA/SampleServer',
    'opc.tcp://opcua.demo-this.com:51210/UA/SampleServer',
    'nsu=http://test.org/UA/Data/ ;i=10221',
    12345);
end;

// This example shows how to write a value into a single node.

class procedure WriteValue.Main;
var
  Client: OpcLabs_EasyOpcUA_TLB._EasyUAClient;
begin
  // Instantiate the client object
  Client := CoEasyUAClient.Create;

  // Perform the operation
  try
    Client.WriteValue(
      //'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=10221',
      12345);
  except
    on E: EOleException do
    begin
      WriteLn(Format('*** Failure: %s', [E.GetBaseException.Message]));
      Exit;
    end;
  end;

end;

// This example shows how to write a value into a single node.

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

// Perform the operation
try
{
    $Client->WriteValue(
        //"http://opcua.demo-this.com:51211/UA/SampleServer", 
        "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer", 
        "nsu=http://test.org/UA/Data/ ;i=10221", 
        12345);
}
catch (com_exception $e)
{
    printf("*** Failure: %s\n", $e->getMessage());
}

// This example shows how to write a value into a single node.

mle_outputtext.Text = ""

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

// Modify value of a node
TRY
    client.WriteValue("http://opcua.demo-this.com:51211/UA/SampleServer", "nsu=http://test.org/UA/Data/ ;i=10221", 12345)
CATCH (OLERuntimeError oleRuntimeError)
    mle_outputtext.Text = mle_outputtext.Text + "*** Failure: " + oleRuntimeError.Description + "~r~n"
    RETURN
END TRY

mle_outputtext.Text = mle_outputtext.Text + "~r~n" 
mle_outputtext.Text = mle_outputtext.Text + "Finished." + "~r~n"

# This example shows how to write a value into a single node.

# 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!
import win32com.client
from pywintypes import com_error

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

# Perform the operation
try:
    client.WriteValue(
        'opc.tcp://opcua.demo-this.com:51210/UA/SampleServer',
        'nsu=http://test.org/UA/Data/ ;i=10221',
        12345)
except com_error as e:
    print('*** Failure: ' + e.args[2][1] + ': ' + e.args[2][2])
    exit()

Rem This example shows how to write a value into a single node.

Public Sub WriteValue_Main_Command_Click()
    OutputText = ""

    ' Instantiate the client object
    Dim Client As New EasyUAClient

    ' Perform the operation
    On Error Resume Next
    Call Client.WriteValue("opc.tcp://opcua.demo-this.com:51210/UA/SampleServer", "nsu=http://test.org/UA/Data/ ;i=10221", 12345)
    If Err.Number <> 0 Then
        OutputText = OutputText & "*** Failure: " & Err.Source & ": " & Err.Description & vbCrLf
        Exit Sub
    End If
    On Error GoTo 0

End Sub

Rem This example shows how to write a value into a single node.

Option Explicit

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

' Perform the operation
On Error Resume Next
Client.WriteValue "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer", "nsu=http://test.org/UA/Data/ ;i=10221", 12345
If Err.Number <> 0 Then
    WScript.Echo "*** Failure: " & Err.Source & ": " & Err.Description
    WScript.Quit
End If
On Error Goto 0

C++
Object Pascal
PHP

// This example shows how to write a value into a single node that is of type ByteString.

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

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

            // Prepare the value to be written
            CComSafeArray<BYTE> array(5);
            array.SetAt(0, 11);
            array.SetAt(1, 22);
            array.SetAt(2, 33);
            array.SetAt(3, 44);
            array.SetAt(4, 55);

            const CComVariant value(array);
            
            // Perform the operation
            ClientPtr->WriteValue(
                //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=10230",
                value);
        }
        // Release all interface pointers BEFORE calling CoUninitialize()
        CoUninitialize();
    }
}

// This example shows how to write a value into a single node that is of type ByteString.

class procedure WriteValue.ByteString;
var
  Client: OpcLabs_EasyOpcUA_TLB._EasyUAClient;
  Values: OleVariant;
begin
  Values := VarArrayCreate([0, 4], varByte);
  Values[0] := 11;
  Values[1] := 22;
  Values[2] := 33;
  Values[3] := 44;
  Values[4] := 55;

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

  // Modify value of a node
  try
    Client.WriteValue(
      //'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=10230', Values);
  except
    on E: EOleException do
    begin
      WriteLn(Format('*** Failure: %s', [E.GetBaseException.Message]));
      Exit;
    end;
  end;

  VarClear(Values);
end;

// This example shows how to write a value into a single node that is of type ByteString.

$Values[0] = 11;
$Values[1] = 22;
$Values[2] = 33;
$Values[3] = 44;
$Values[4] = 55;

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

// Modify value of a node
try
{
    $Client->WriteValue(
        //"http://opcua.demo-this.com:51211/UA/SampleServer", 
        "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer", 
        "nsu=http://test.org/UA/Data/ ;i=10230", 
        $Values);
}
catch (com_exception $e)
{
    printf("*** Failure: %s\n", $e->getMessage());
}

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

_EasyUAClient Interface
_EasyUAClient Members

Send Documentation Feedback. Resources: Knowledge Base. Technical support: Online Forums, FAQ.