OPC Studio User's Guide and Reference
Writing to OPC Classic Items
Client and Subscriber Development > Development Models > Imperative Programming Model > Imperative Programming Model for OPC Data (Classic and UA) > Modifying Information (OPC Data) > Writing to OPC Classic Items
In This Topic

A single item

If you want to write a data value into a specific OPC item, call the WriteItemValue method, passing it the data value you want to write, arguments for machine name, server class, ItemID, and an optional data type.

.NET

// This example shows how to write a value into a single item.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

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

namespace DocExamples.DataAccess._EasyDAClient
{
    partial class WriteItemValue
    {
        public static void Main1()
        {
            // Instantiate the client object.
            var client = new EasyDAClient();

            try
            {
                client.WriteItemValue("", "OPCLabs.KitServer.2", "Simulation.Register_I4", 12345);
            }
            catch (OpcException opcException)
            {
                Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message);
                return;
            }
            Console.WriteLine("Success");
        }
    }
}
# This example shows how to write a value into a single item.
#
# Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

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

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

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

try {
    [IEasyDAClientExtension]::WriteItemValue($client, "", "OPCLabs.KitServer.2", "Simulation.Register_I4", 12345)
}
catch [OpcException] {
    Write-Host "*** Failure: $($PSItem.Exception.GetBaseException().Message)"
    return
}

Write-Host "Success"
# This example shows how to write a value into a single item.
#
# 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 .
# The QuickOPC package is needed. Install it using "pip install opclabs_quickopc".
import opclabs_quickopc

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


# Instantiate the client object.
client = EasyDAClient()

# Perform the operation
try:
    IEasyDAClientExtension.WriteItemValue(client, '', 'OPCLabs.KitServer.2', 'Simulation.Register_I4', 12345)
except OpcException as opcException:
    print('*** Failure: ' + opcException.GetBaseException().Message, sep='')
    exit()

print('Finished.')
' Shows how to write into an OPC item that is of array type, and read the array value back.
'
' Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

Imports OpcLabs.EasyOpc.DataAccess
Imports OpcLabs.EasyOpc.OperationModel

Namespace DataAccess._EasyDAClient
    Partial Friend Class WriteItemValue
        Public Shared Sub Main1()
            Dim client = New EasyDAClient()

            Try
                client.WriteItemValue("", "OPCLabs.KitServer.2", "Simulation.Register_I4", 12345)
            Catch opcException As OpcException
                Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message)
                Exit Sub
            End Try
        End Sub
    End Class
End Namespace

COM

// This example shows how to write a value into a single item.
//
// Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

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

try
{
    $value = $Client->WriteItemValue("", "OPCLabs.KitServer.2", "Simulation.Register_I4", 12345);
}
catch (com_exception $e)
{
    printf("*** Failure: %s\n", $e->getMessage());
    Exit();
}
// This example shows how to write a value into a single item.
//
// Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

class procedure WriteItemValue.Main;
var
  Client: OpcLabs_EasyOpcClassic_TLB._EasyDAClient;
begin
  // Instantiate the client object
  Client := CoEasyDAClient.Create;

  try
    Client.WriteItemValue('', 'OPCLabs.KitServer.2', 'Simulation.Register_I4', 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 item.

mle_outputtext.Text = ""

// Instantiate the client object
OLEObject client
client = CREATE OLEObject
client.ConnectToNewObject("OpcLabs.EasyOpc.DataAccess.EasyDAClient")

// Modify value of an item
TRY
    client.WriteItemValue("", "OPCLabs.KitServer.2", "Simulation.Register_I4", 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 item.
#
# 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.DataAccess.EasyDAClient') 

# Perform the operation
try:
    client.WriteItemValue('', 'OPCLabs.KitServer.2', 'Simulation.Register_I4', 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 item.
REM
REM Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

Private Sub WriteItemValue_Main_Command_Click()
    OutputText = ""
    
    ' Instantiate the client object
    Dim client As New EasyDAClient

    On Error Resume Next
    Call client.WriteItemValue("", "OPCLabs.KitServer.2", "Simulation.Register_I4", 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 item.
Rem
Rem Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

Option Explicit

Dim Client: Set Client = CreateObject("OpcLabs.EasyOpc.DataAccess.EasyDAClient")
On Error Resume Next
Client.WriteItemValue "", "OPCLabs.KitServer.2", "Simulation.Register_I4", 12345
If Err.Number <> 0 Then
    WScript.Echo "*** Failure: " & Err.Source & ": " & Err.Description
    WScript.Quit
End If
On Error Goto 0

In QuickOPC.NET, you can also pass in the ServerDescriptor and DAItemDescriptor objects in place of corresponding individual arguments.

.NET

// This example shows how to write a value into a single OPC XML-DA item.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

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

namespace DocExamples.DataAccess.Xml
{
    class WriteItemValue
    {
        public static void Main1Xml()
        {
            // Instantiate the client object.
            var client = new EasyDAClient();

            try
            {
                client.WriteItemValue(
                    "http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx", 
                    "Static/Analog Types/Int", 
                    12345);
            }
            catch (OpcException opcException)
            {
                Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message);
            }
        }
    }
}
# This example shows how to write a value into a single OPC XML-DA item.
#
# 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 .
# The QuickOPC package is needed. Install it using "pip install opclabs_quickopc".
import opclabs_quickopc

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


# Instantiate the client object.
client = EasyDAClient()

# Perform the operation
try:
    IEasyDAClientExtension.WriteItemValue(client,
        ServerDescriptor('http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx'),
        DAItemDescriptor('Static/Analog Types/Int'),
        Int32(12345))
except OpcException as opcException:
    print('*** Failure: ' + opcException.GetBaseException().Message, sep='')
    exit()

print('Finished.')
' This example shows how to write a value into a single OPC XML-DA item.
'
' Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

Imports OpcLabs.EasyOpc.DataAccess
Imports OpcLabs.EasyOpc.OperationModel

Namespace DataAccess.Xml
    Partial Friend Class WriteItemValue
        Public Shared Sub Main1Xml()
            Dim client = New EasyDAClient()

            Try
                client.WriteItemValue("http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx", "Static/Analog Types/Int", 12345)
            Catch opcException As OpcException
                Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message)
                Exit Sub
            End Try
        End Sub
    End Class
End Namespace

COM

// This example shows how to write a value into a single OPC XML-DA item.
//
// Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

class procedure WriteItemValue.MainXml;
var
  Arguments: OleVariant;
  Client: OpcLabs_EasyOpcClassic_TLB._EasyDAClient;
  ItemValueArguments1: _DAItemValueArguments;
  Results: OleVariant;
  OperationResult: _OperationResult;
begin
  ItemValueArguments1 := CoDAItemValueArguments.Create;
  ItemValueArguments1.ServerDescriptor.UrlString := 'http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx';
  ItemValueArguments1.ItemDescriptor.ItemID := 'Static/Analog Types/Int';
  ItemValueArguments1.Value := 12345;

  Arguments := VarArrayCreate([0, 0], varVariant);
  Arguments[0] := ItemValueArguments1;

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

  TVarData(Results).VType := varArray or varVariant;
  TVarData(Results).VArray := PVarArray(
    Client.WriteMultipleItemValues(Arguments));

  OperationResult := IInterface(Results[0]) as _OperationResult;
  if Not OperationResult.Succeeded then
      WriteLn(' *** Failure: ', OperationResult.Exception.GetBaseException.Message);
  
  VarClear(Results);
  VarClear(Arguments);

end;
// This example shows how to write a value into a single OPC XML-DA item.
//
// Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

$ItemValueArguments1 = new COM("OpcLabs.EasyOpc.DataAccess.OperationModel.DAItemValueArguments");
$ItemValueArguments1->ServerDescriptor->UrlString = "http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx";
$ItemValueArguments1->ItemDescriptor->ItemID = "Static/Analog Types/Int";
$ItemValueArguments1->Value = 12345;

$arguments[0] = $ItemValueArguments1;

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

$results = $Client->WriteMultipleItemValues($arguments);

$OperationResult = $results[0];
if ($OperationResult->Succeeded)
    printf("Result: success\n");
else
    printf("Result: %s\n", $OperationResult->ErrorMessageBrief);
Rem This example shows how to write a value into a single OPC XML-DA item.
Rem
Rem Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

Private Sub WriteItemValue_MainXml_Command_Click()
    OutputText = ""
    
    Dim itemValueArguments1 As New DAItemValueArguments
    itemValueArguments1.serverDescriptor.UrlString = "http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx"
    itemValueArguments1.ItemDescriptor.ItemId = "Static/Analog Types/Int"
    itemValueArguments1.SetValue 12345
    
    Dim arguments(0) As Variant
    Set arguments(0) = itemValueArguments1

    ' Instantiate the client object
    Dim client As New EasyDAClient

    ' Modify values of nodes
    Dim results() As Variant
    results = client.WriteMultipleItemValues(arguments)

    Dim operationResult As operationResult: Set operationResult = results(0)
    If Not operationResult.Succeeded Then
        OutputText = OutputText & "*** Failure: " & operationResult.ErrorMessageBrief & vbCrLf
    End If
End Sub
Rem This example shows how to write a value into a single OPC XML-DA item.
Rem
Rem Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

Option Explicit

Dim ItemValueArguments1: Set ItemValueArguments1 = CreateObject("OpcLabs.EasyOpc.DataAccess.OperationModel.DAItemValueArguments")
ItemValueArguments1.ServerDescriptor.UrlString = "http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx"
ItemValueArguments1.ItemDescriptor.ItemID = "Static/Analog Types/Int"
ItemValueArguments1.Value = 12345

Dim arguments(0)
Set arguments(0) = ItemValueArguments1

Dim Client: Set Client = CreateObject("OpcLabs.EasyOpc.DataAccess.EasyDAClient")
Dim results: results = Client.WriteMultipleItemValues(arguments)

Dim OperationResult: Set OperationResult = results(0)
If OperationResult.Succeeded Then
    WScript.Echo "Result: success"
Else
    WScript.Echo "Result: " & OperationResult.Exception.GetBaseException.Message
End If

 

QuickOPC supports OPC XML-DA also on Linux and macOS.

Multiple items

For writing data values into multiple OPC items in an efficient manner, call the WriteMultipleItemValues method.

In QuickOPC.NET, you pass in an array of DAItemValueArguments objects, each specifying the location of OPC item, and the value to be written.

For an efficient writing into several items, use the WriteMultipleItemValues method.

Example 1

.NET

// Shows how to write into multiple OPC items using a single method call, and read multiple item values back.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

using System;
using System.Diagnostics;
using OpcLabs.BaseLib.OperationModel;
using OpcLabs.EasyOpc.DataAccess;
using OpcLabs.EasyOpc.DataAccess.OperationModel;

namespace DocExamples.DataAccess._EasyDAClient
{
    partial class WriteMultipleItemValues
    {
        public static void Main1()
        {
            // Instantiate the client object.
            var client = new EasyDAClient();

            Console.WriteLine("Writing multiple item values...");
            OperationResult[] resultArray = client.WriteMultipleItemValues(
                new[] { 
                    new DAItemValueArguments("", "OPCLabs.KitServer.2", "Simulation.Register_I4", 12345),
                    new DAItemValueArguments("", "OPCLabs.KitServer.2", "Simulation.Register_BOOL", true),
                    new DAItemValueArguments("", "OPCLabs.KitServer.2", "Simulation.Register_R4", 234.56)
                });
            
            for (int i = 0; i < resultArray.Length; i++)
            {
                Debug.Assert(resultArray[i] != null);
                if (resultArray[i].Succeeded)
                    Console.WriteLine($"Results[{i}]: success");
                else
                {
                    Debug.Assert(!(resultArray[i].Exception is null));
                    Console.WriteLine($"Results[{i}] *** Failure: {resultArray[i].ErrorMessageBrief}");
                }
            }

            Console.WriteLine();
            Console.WriteLine("Reading multiple item values...");
            ValueResult[] valueResultArray = client.ReadMultipleItemValues("OPCLabs.KitServer.2",
                new DAItemDescriptor[] { 
                        "Simulation.Register_I4", 
                        "Simulation.Register_BOOL", 
                        "Simulation.Register_R4" });

            for (int i = 0; i < valueResultArray.Length; i++)
            {
                Debug.Assert(valueResultArray[i] != null);
                Console.WriteLine($"valueResultArray[{i}]: {valueResultArray[i]}");
            }


            // Example output:
            //
            //Writing multiple item values...
            //Results[0]: success
            //Results[1]: success
            //Results[2]: success
            //
            //Reading multiple item values...
            //valueResultArray[0]: Success; 12345 {System.Int32}
            //valueResultArray[1]: Success; True {System.Boolean}
            //valueResultArray[2]: Success; 234.56 {System.Single}
        }
    }
}
# Shows how to write into multiple OPC items using a single method call, and read multiple item values back.
#
# Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

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

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

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

Write-Host "Writing multiple item values..."
$resultArray = $client.WriteMultipleItemValues(@(
    (New-Object DAItemValueArguments("", "OPCLabs.KitServer.2", "Simulation.Register_I4", 12345)),
    (New-Object DAItemValueArguments("", "OPCLabs.KitServer.2", "Simulation.Register_BOOL", $true)),
    (New-Object DAItemValueArguments("", "OPCLabs.KitServer.2", "Simulation.Register_R4", 234.56))
    ))

for ($i = 0; $i -lt $resultArray.Length; $i++) {
    $result = $resultArray[$i]
    if ($result.Succeeded) {
        Write-Host "Result $($i): success"
    }
    else {
        Write-Host "Result $($i) *** Failure: $($result.ErrorMessageBrief)"
    }
}

Write-Host 
Write-Host "Reading multiple item values..."
$valueResultArray = [IEasyDAClientExtension]::ReadMultipleItemValues($client, 
    "OPCLabs.KitServer.2", @(
        (New-Object DAItemDescriptor("Simulation.Register_I4")),
        (New-Object DAItemDescriptor("Simulation.Register_BOOL")),
        (New-Object DAItemDescriptor("Simulation.Register_R4"))
        ))

for ($i = 0; $i -lt $valueResultArray.Length; $i++) {
    $valueResult = $valueResultArray[$i]
    Write-Host "valueResultArray[$($i)]: $($valueResult)"
}


# Example output:
#
#Writing multiple item values...
#Result 0: success
#Result 1: success
#Result 2: success
#
#Reading multiple item values...
#valueResultArray[0]: Success; 12345 {System.Int32}
#valueResultArray[1]: Success; True {System.Boolean}
#valueResultArray[2]: Success; 234.56 {System.Single}

# Shows how to write into multiple OPC items using a single method call, and read multiple item values back.
#
# 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 .
# The QuickOPC package is needed. Install it using "pip install opclabs_quickopc".
import opclabs_quickopc

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


# Instantiate the client object.
client = EasyDAClient()

print('Writing multiple item values...')
operationResultArray = client.WriteMultipleItemValues([
    DAItemValueArguments(ServerDescriptor('OPCLabs.KitServer.2'), DAItemDescriptor('Simulation.Register_I4'),
                         12345),
    DAItemValueArguments(ServerDescriptor('OPCLabs.KitServer.2'), DAItemDescriptor('Simulation.Register_BOOL'),
                         True),
    DAItemValueArguments(ServerDescriptor('OPCLabs.KitServer.2'), DAItemDescriptor('Simulation.Register_R4'),
                         234.56),
    ])

for i, operationResult in enumerate(operationResultArray):
    assert operationResult is not None
    if operationResult.Succeeded:
        print('operationResultArray[', i, ']: success', sep='')
    else:
        assert operationResult.Exception is not None
        print('operationResultArray[', i, '] *** Failure: ', operationResult.ErrorMessageBrief, sep='')

print('Reading multiple item values...')
try:
    valueResultArray = IEasyDAClientExtension.ReadMultipleItemValues(client, ServerDescriptor('OPCLabs.KitServer.2'), [
        DAItemDescriptor('Simulation.Register_I4'),
        DAItemDescriptor('Simulation.Register_BOOL'),
        DAItemDescriptor('Simulation.Register_R4'),
    ])
except OpcException as opcException:
    print('*** Failure: ' + opcException.GetBaseException().Message)
    exit()

for i, valueResult in enumerate(valueResultArray):
    assert valueResult is not None
    if valueResult.Succeeded:
        print('valueResultArray[', i, '].Value: ', valueResult.Value, sep='')
    else:
        assert valueResult.Exception is not None
        print('valueResultArray[', i, '] *** Failure: ', valueResult.ErrorMessageBrief, sep='')
' This example shows how to write values into multiple items.
'
' Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

Imports OpcLabs.BaseLib.OperationModel
Imports OpcLabs.EasyOpc.DataAccess
Imports OpcLabs.EasyOpc.DataAccess.OperationModel

Namespace DataAccess._EasyDAClient
    Partial Friend Class WriteMultipleItemValues
        Public Shared Sub Main1()
            Dim client = New EasyDAClient()

            Dim argumentsArray = New DAItemValueArguments() { _
                New DAItemValueArguments("", "OPCLabs.KitServer.2", "Simulation.Register_I4", 12345), _
                New DAItemValueArguments("", "OPCLabs.KitServer.2", "Simulation.Register_BOOL", True), _
                New DAItemValueArguments("", "OPCLabs.KitServer.2", "Simulation.Register_R4", 234.56) _
            }

            Dim resultArray As OperationResult() = client.WriteMultipleItemValues(argumentsArray)

            For i = 0 To resultArray.Length - 1
                Debug.Assert(resultArray(i) IsNot Nothing)

                If resultArray(i).Succeeded Then
                    Console.WriteLine("Results[{0}]: success", i)
                Else
                    Console.WriteLine("Results[{0}] *** Failure: {1}", i, resultArray(i).ErrorMessageBrief)
                End If
            Next i

            Console.WriteLine("Reading multiple item values...")
            Dim valueResultArray() As ValueResult = client.ReadMultipleItemValues("OPCLabs.KitServer.2", _
                New DAItemDescriptor() { _
                    "Simulation.Register_I4",
                    "Simulation.Register_BOOL",
                    "Simulation.Register_R4"})

            For i = 0 To valueResultArray.Length - 1
                Debug.Assert(valueResultArray(i) IsNot Nothing)
                Console.WriteLine("valueResultArray[{0}]: {1}", i, valueResultArray(i))
            Next i

        End Sub
    End Class
End Namespace

COM

// This example shows how to write values into 3 items at once.
//
// Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

class procedure WriteMultipleItemValues.Main;
var
  Arguments: OleVariant;
  Client: OpcLabs_EasyOpcClassic_TLB._EasyDAClient;
  I: Cardinal;
  ItemValueArguments1: _DAItemValueArguments;
  ItemValueArguments2: _DAItemValueArguments;
  ItemValueArguments3: _DAItemValueArguments;
  Results: OleVariant;
  OperationResult: _OperationResult;

begin
  ItemValueArguments1 := CoDAItemValueArguments.Create;
  ItemValueArguments1.ServerDescriptor.ServerClass := 'OPCLabs.KitServer.2';
  ItemValueArguments1.ItemDescriptor.ItemID := 'Simulation.Register_I4';
  ItemValueArguments1.Value := 23456;

  ItemValueArguments2 := CoDAItemValueArguments.Create;
  ItemValueArguments2.ServerDescriptor.ServerClass := 'OPCLabs.KitServer.2';
  ItemValueArguments2.ItemDescriptor.ItemID := 'Simulation.Register_R8';
  ItemValueArguments2.Value := 2.34567890;

  ItemValueArguments3 := CoDAItemValueArguments.Create;
  ItemValueArguments3.ServerDescriptor.ServerClass := 'OPCLabs.KitServer.2';
  ItemValueArguments3.ItemDescriptor.ItemID := 'Simulation.Register_BSTR';
  ItemValueArguments3.Value := 'ABC';

  Arguments := VarArrayCreate([0, 2], varVariant);
  Arguments[0] := ItemValueArguments1;
  Arguments[1] := ItemValueArguments2;
  Arguments[2] := ItemValueArguments3;

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

  // Modify values of nodes
  TVarData(Results).VType := varArray or varVariant;
  TVarData(Results).VArray := PVarArray(
    Client.WriteMultipleItemValues(Arguments));

  // Display results
  for I := VarArrayLowBound(Results, 1) to VarArrayHighBound(Results, 1) do
  begin
    OperationResult := IInterface(Results[I]) as _OperationResult;
    if OperationResult.Succeeded then
      WriteLn('Result ', I, ' success')
    else
      WriteLn('Result ', I, ' *** Failure: ', OperationResult.Exception.GetBaseException.Message);
  end;
  
  VarClear(Results);
  VarClear(Arguments);
end;
// This example shows how to write values into 3 items at once.
//
// Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

$ItemValueArguments1 = new COM("OpcLabs.EasyOpc.DataAccess.OperationModel.DAItemValueArguments");
$ItemValueArguments1->ServerDescriptor->ServerClass = "OPCLabs.KitServer.2";
$ItemValueArguments1->ItemDescriptor->ItemID = "Simulation.Register_I4";
$ItemValueArguments1->Value = 23456;

$ItemValueArguments2 = new COM("OpcLabs.EasyOpc.DataAccess.OperationModel.DAItemValueArguments");
$ItemValueArguments2->ServerDescriptor->ServerClass = "OPCLabs.KitServer.2";
$ItemValueArguments2->ItemDescriptor->ItemID = "Simulation.Register_R8";
$ItemValueArguments2->Value = 2.34567890;

$ItemValueArguments3 = new COM("OpcLabs.EasyOpc.DataAccess.OperationModel.DAItemValueArguments");
$ItemValueArguments3->ServerDescriptor->ServerClass = "OPCLabs.KitServer.2";
$ItemValueArguments3->ItemDescriptor->ItemID = "Simulation.Register_BSTR";
$ItemValueArguments3->Value = "ABC";

$arguments[0] = $ItemValueArguments1;
$arguments[1] = $ItemValueArguments2;
$arguments[2] = $ItemValueArguments3;

$Client = new COM("OpcLabs.EasyOpc.DataAccess.EasyDAClient");
$results = $Client->WriteMultipleItemValues($arguments);

for ($i = 0; $i < count($results); $i++)
{
    $OperationResult = $results[$i];
    if ($OperationResult->Succeeded)
        printf("Result %d: success\n", $i);
    else
        printf("Result d: s\n", $i, $OperationResult->ErrorMessageBrief);
}
// Shows how to write into multiple OPC items using a single method call, and itemValue multiple item values back.

mle_outputtext.Text = ""

// Instantiate the client object
OLEObject client
client = CREATE OLEObject
client.ConnectToNewObject("OpcLabs.EasyOpc.DataAccess.EasyDAClient")

// Prepare arguments. 

OLEObject itemValueArguments1
itemValueArguments1 = CREATE OLEObject
itemValueArguments1.ConnectToNewObject("OpcLabs.EasyOpc.DataAccess.OperationModel.DAItemValueArguments")
itemValueArguments1.ServerDescriptor.ServerClass = "OPCLabs.KitServer.2"
itemValueArguments1.ItemDescriptor.ItemID = "Simulation.Register_I4"
itemValueArguments1.Value = 12345

OLEObject itemValueArguments2
itemValueArguments2 = CREATE OLEObject
itemValueArguments2.ConnectToNewObject("OpcLabs.EasyOpc.DataAccess.OperationModel.DAItemValueArguments")
itemValueArguments2.ServerDescriptor.ServerClass = "OPCLabs.KitServer.2"
itemValueArguments2.ItemDescriptor.ItemID = "Simulation.Register_BOOL"
itemValueArguments2.Value = TRUE

OLEObject itemValueArguments3
itemValueArguments3 = CREATE OLEObject
itemValueArguments3.ConnectToNewObject("OpcLabs.EasyOpc.DataAccess.OperationModel.DAItemValueArguments")
itemValueArguments3.ServerDescriptor.ServerClass = "OPCLabs.KitServer.2"
itemValueArguments3.ItemDescriptor.ItemID = "Simulation.Register_R4"
itemValueArguments3.Value = 234.56

OLEObject itemValueArgumentsList
itemValueArgumentsList = CREATE OLEObject
itemValueArgumentsList.ConnectToNewObject("OpcLabs.BaseLib.Collections.ElasticVector")
itemValueArgumentsList.Add(itemValueArguments1)
itemValueArgumentsList.Add(itemValueArguments2)
itemValueArgumentsList.Add(itemValueArguments3)

// Modify value of nodes

OLEObject operationResultList
operationResultList = client.WriteItemValueList(itemValueArgumentsList)

// Display results
Int i
FOR i = 0 TO operationResultList.Count - 1
    OLEObject operationResult
    operationResult = operationResultList.Item[i]
    IF operationResult.Succeeded THEN
        mle_outputtext.Text = mle_outputtext.Text + "Result " + String(i) + ": success" + "~r~n"
    ELSE
        mle_outputtext.Text = mle_outputtext.Text + "Result " + String(i) + ": " + operationResult.Exception.GetBaseException().Message + "~r~n"
    END IF    
NEXT

mle_outputtext.Text = mle_outputtext.Text + "~r~n" 
mle_outputtext.Text = mle_outputtext.Text + "Finished." + "~r~n" 
REM This example shows how to write values into 3 items at once.
REM
REM Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

Private Sub WriteMultipleItemValues_Main_Command_Click()
    OutputText = ""
    
    Dim itemValueArguments1 As New DAItemValueArguments
    itemValueArguments1.serverDescriptor.ServerClass = "OPCLabs.KitServer.2"
    itemValueArguments1.ItemDescriptor.itemId = "Simulation.Register_I4"
    itemValueArguments1.SetValue 23456
    
    Dim itemValueArguments2 As New DAItemValueArguments
    itemValueArguments2.serverDescriptor.ServerClass = "OPCLabs.KitServer.2"
    itemValueArguments2.ItemDescriptor.itemId = "Simulation.Register_R8"
    itemValueArguments2.SetValue 2.3456789
    
    Dim itemValueArguments3 As New DAItemValueArguments
    itemValueArguments3.serverDescriptor.ServerClass = "OPCLabs.KitServer.2"
    itemValueArguments3.ItemDescriptor.itemId = "Simulation.Register_BSTR"
    itemValueArguments3.SetValue "ABC"
    
    Dim arguments(2) As Variant
    Set arguments(0) = itemValueArguments1
    Set arguments(1) = itemValueArguments2
    Set arguments(2) = itemValueArguments3

    ' Instantiate the client object
    Dim client As New EasyDAClient

    ' Modify values of nodes
    Dim results() As Variant
    results = client.WriteMultipleItemValues(arguments)

    ' Display results
    Dim i: For i = LBound(results) To UBound(results)
        Dim operationResult As operationResult: Set operationResult = results(i)
        If operationResult.Succeeded Then
            OutputText = OutputText & "result " & i & " success" & vbCrLf
        Else
            OutputText = OutputText & "result " & i & " *** Failure: " & operationResult.ErrorMessageBrief & vbCrLf
        End If
    Next
End Sub
Rem This example shows how to write values into 3 items at once.
Rem
Rem Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

Option Explicit

Dim ItemValueArguments1: Set ItemValueArguments1 = CreateObject("OpcLabs.EasyOpc.DataAccess.OperationModel.DAItemValueArguments")
ItemValueArguments1.ServerDescriptor.ServerClass = "OPCLabs.KitServer.2"
ItemValueArguments1.ItemDescriptor.ItemID = "Simulation.Register_I4"
ItemValueArguments1.Value = 23456

Dim ItemValueArguments2: Set ItemValueArguments2 = CreateObject("OpcLabs.EasyOpc.DataAccess.OperationModel.DAItemValueArguments")
ItemValueArguments2.ServerDescriptor.ServerClass = "OPCLabs.KitServer.2"
ItemValueArguments2.ItemDescriptor.ItemID = "Simulation.Register_R8"
ItemValueArguments2.Value = 2.34567890

Dim ItemValueArguments3: Set ItemValueArguments3 = CreateObject("OpcLabs.EasyOpc.DataAccess.OperationModel.DAItemValueArguments")
ItemValueArguments3.ServerDescriptor.ServerClass = "OPCLabs.KitServer.2"
ItemValueArguments3.ItemDescriptor.ItemID = "Simulation.Register_BSTR"
ItemValueArguments3.Value = "ABC"

Dim arguments(2)
Set arguments(0) = ItemValueArguments1
Set arguments(1) = ItemValueArguments2
Set arguments(2) = ItemValueArguments3

Dim Client: Set Client = CreateObject("OpcLabs.EasyOpc.DataAccess.EasyDAClient")
Dim results: results = Client.WriteMultipleItemValues(arguments)

Dim i: For i = LBound(results) To UBound(results)
    Dim OperationResult: Set OperationResult = results(i)
    If OperationResult.Succeeded Then
        WScript.Echo "Result " & i & ": success"
    Else
        WScript.Echo "Result " & i & ": " & OperationResult.Exception.GetBaseException.Message
    End If
Next

Example 2

.NET

// This example shows how to write values into 3 items at once, test for success of each write and display the exception 
// message in case of failure.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

using System;
using System.Diagnostics;
using OpcLabs.BaseLib.OperationModel;
using OpcLabs.EasyOpc.DataAccess;
using OpcLabs.EasyOpc.DataAccess.OperationModel;

namespace DocExamples.DataAccess._EasyDAClient
{
    partial class WriteMultipleItemValues
    {
        public static void TestSuccess()
        {
            // Instantiate the client object.
            var client = new EasyDAClient();

            Console.WriteLine("Writing multiple item values...");
            OperationResult[] resultArray = client.WriteMultipleItemValues(
                new[] { 
                    new DAItemValueArguments("", "OPCLabs.KitServer.2", "Simulation.Register_I4", 23456),
                    new DAItemValueArguments("", "OPCLabs.KitServer.2", "Simulation.Register_R8", 
                        "This string cannot be converted to VT_R8"),
                    new DAItemValueArguments("", "OPCLabs.KitServer.2", "UnknownItem", "ABC")
                });


            for (int i = 0; i < resultArray.Length; i++)
            {
                Debug.Assert(resultArray[i] != null);
                if (resultArray[i].Succeeded)
                    Console.WriteLine("Result {0}: success", i);
                else
                {
                    Debug.Assert(!(resultArray[i].Exception is null));
                    Console.WriteLine("Result {0} *** Failure: {1}", i, resultArray[i].ErrorMessageBrief);
                }
            }
        }


        // Example output:
        //
        //Writing multiple item values...
        //Result 0: success
        //Result 1 *** Failure: Type mismatch.  [...]
        //Result 2 *** Failure: The item is no longer available in the server address space. [...]
    }
}
' This example shows how to write values into 3 items at once, test for success of each write and display the exception 
' message in case of failure.
'
' Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

Imports OpcLabs.BaseLib.OperationModel
Imports OpcLabs.EasyOpc.DataAccess
Imports OpcLabs.EasyOpc.DataAccess.OperationModel

Namespace DataAccess._EasyDAClient
    Partial Friend Class WriteMultipleItemValues
        Public Shared Sub TestSuccess()
            ' Instantiate the client object.
            Dim client = New EasyDAClient()

            Console.WriteLine("Writing multiple item values...")
            Dim resultArray As OperationResult() = client.WriteMultipleItemValues(New DAItemValueArguments() {
                New DAItemValueArguments("", "OPCLabs.KitServer.2", "Simulation.Register_I4", 23456),
                New DAItemValueArguments("", "OPCLabs.KitServer.2", "Simulation.Register_R8",
                        "This string cannot be converted to VT_R8"),
                New DAItemValueArguments("", "OPCLabs.KitServer.2", "UnknownItem", "ABC")
            })

            For i = 0 To resultArray.Length - 1
                Debug.Assert(resultArray(i) IsNot Nothing)

                If resultArray(i).Succeeded Then
                    Console.WriteLine("Result {0}: success", i)
                Else
                    Debug.Assert(resultArray(i).Exception IsNot Nothing)
                    Console.WriteLine("Result {0} *** Failure: {1}", i, resultArray(i).ErrorMessageBrief)
                End If
            Next i
        End Sub

        ' Example output
        '
        'Writing multiple item values...
        'Result 0: success
        'Result 1 *** Failure: Type mismatch.  [...]
        'Result 2 *** Failure: The item Is no longer available In the server address space. [...]
    End Class
End Namespace

COM

// This example shows how to write values into 3 items at once, test for success of each write and display the exception 
// message in case of failure.
//
// Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

$ItemValueArguments1 = new COM("OpcLabs.EasyOpc.DataAccess.OperationModel.DAItemValueArguments");
$ItemValueArguments1->ServerDescriptor->ServerClass = "OPCLabs.KitServer.2";
$ItemValueArguments1->ItemDescriptor->ItemID = "Simulation.Register_I4";
$ItemValueArguments1->Value = 23456;

$ItemValueArguments2 = new COM("OpcLabs.EasyOpc.DataAccess.OperationModel.DAItemValueArguments");
$ItemValueArguments2->ServerDescriptor->ServerClass = "OPCLabs.KitServer.2";
$ItemValueArguments2->ItemDescriptor->ItemID = "Simulation.Register_R8";
$ItemValueArguments2->Value = "This string cannot be converted to VT_R8";

$ItemValueArguments3 = new COM("OpcLabs.EasyOpc.DataAccess.OperationModel.DAItemValueArguments");
$ItemValueArguments3->ServerDescriptor->ServerClass = "OPCLabs.KitServer.2";
$ItemValueArguments3->ItemDescriptor->ItemID = "UnknownItem";
$ItemValueArguments3->Value = "ABC";

$arguments[0] = $ItemValueArguments1;
$arguments[1] = $ItemValueArguments2;
$arguments[2] = $ItemValueArguments3;

$Client = new COM("OpcLabs.EasyOpc.DataAccess.EasyDAClient");
$results = $Client->WriteMultipleItemValues($arguments);

for ($i = 0; $i < count($results); $i++)
{
    $OperationResult = $results[$i];
    if ($OperationResult->Succeeded)
        printf("Result %d: success\n", $i);
    else
        printf("Result d: s\n", $i, $OperationResult->ErrorMessageBrief);
}
Rem This example shows how to write values into 3 items at once, test for success of each write and display the exception 
Rem message in case of failure.
Rem
Rem Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

Option Explicit

Dim ItemValueArguments1: Set ItemValueArguments1 = CreateObject("OpcLabs.EasyOpc.DataAccess.OperationModel.DAItemValueArguments")
ItemValueArguments1.ServerDescriptor.ServerClass = "OPCLabs.KitServer.2"
ItemValueArguments1.ItemDescriptor.ItemID = "Simulation.Register_I4"
ItemValueArguments1.Value = 23456

Dim ItemValueArguments2: Set ItemValueArguments2 = CreateObject("OpcLabs.EasyOpc.DataAccess.OperationModel.DAItemValueArguments")
ItemValueArguments2.ServerDescriptor.ServerClass = "OPCLabs.KitServer.2"
ItemValueArguments2.ItemDescriptor.ItemID = "Simulation.Register_R8"
ItemValueArguments2.Value = "This string cannot be converted to VT_R8"

Dim ItemValueArguments3: Set ItemValueArguments3 = CreateObject("OpcLabs.EasyOpc.DataAccess.OperationModel.DAItemValueArguments")
ItemValueArguments3.ServerDescriptor.ServerClass = "OPCLabs.KitServer.2"
ItemValueArguments3.ItemDescriptor.ItemID = "UnknownItem"
ItemValueArguments3.Value = "ABC"

Dim arguments(2)
Set arguments(0) = ItemValueArguments1
Set arguments(1) = ItemValueArguments2
Set arguments(2) = ItemValueArguments3

Dim Client: Set Client = CreateObject("OpcLabs.EasyOpc.DataAccess.EasyDAClient")
Dim results: results = Client.WriteMultipleItemValues(arguments)

Dim i: For i = LBound(results) To UBound(results)
    Dim OperationResult: Set OperationResult = results(i)
    If OperationResult.Succeeded Then
        WScript.Echo "Result " & i & ": success"
    Else
        WScript.Echo "Result " & i & ": " & OperationResult.Exception.GetBaseException.Message
    End If
Next

Advanced topics

If you need to write a combination of value, timestamps, and status code be written, and your OPC server support this, see Writing value, timestamps and status code (OPC UA).  

 

 

See Also

Examples - OPC Data Access

Examples - OPC XML-DA