QuickOPC User's Guide and Reference
ValueTypeCode Property (_UAWriteArguments)
Example 



OpcLabs.EasyOpcUA Assembly > OpcLabs.EasyOpc.UA.OperationModel.ComTypes Namespace > _UAWriteArguments Interface : ValueTypeCode Property
Specifies the type code that should be used when writing the Value attribute.
Syntax
'Declaration
 
Property ValueTypeCode As TypeCode
'Usage
 
Dim instance As _UAWriteArguments
Dim value As TypeCode
 
instance.ValueTypeCode = value
 
value = instance.ValueTypeCode
TypeCode ValueTypeCode {get; set;}
property TypeCode ValueTypeCode {
   TypeCode get();
   void set (    TypeCode value);
}

Property Value

The type code that should be used when writing the Value attribute.
Remarks

When the type code is System.TypeCode.Empty, and the OpcLabs.EasyOpc.UA.OperationModel.UAAttributeArguments.AttributeId is equal to OpcLabs.EasyOpc.UA.UAAttributeId.Value, it means that 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.

Example

.NET

COM

// This example shows how to write values into 3 nodes at once, specifying a type code explicitly. It tests for success of 
// each write and displays the exception message in case of failure.
//
// Reasons for specifying the type explicitly might be:
// - The data type in the server has subtypes, and the client therefore needs to pick the subtype to be written.
// - The data type that the reports is incorrect.
// - Writing with an explicitly specified type is more efficient.
//
// Alternative ways of specifying the type are using the ValueType or ValueTypeFullName properties.

using System;
using OpcLabs.BaseLib.OperationModel;
using OpcLabs.EasyOpc.UA;
using OpcLabs.EasyOpc.UA.OperationModel;

namespace UADocExamples._EasyUAClient
{
    partial class WriteMultipleValues
    {
        public static void ValueTypeCode()
        {
            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("Modifying values of nodes...");
            OperationResult[] operationResultArray = client.WriteMultipleValues(new[]
                {
                    new UAWriteValueArguments(endpointDescriptor, 
                        "nsu=http://test.org/UA/Data/ ;i=10221", 23456) 
                        {ValueTypeCode = TypeCode.Int32},    // here is the type explicitly specified
                    new UAWriteValueArguments(endpointDescriptor,
                        "nsu=http://test.org/UA/Data/ ;i=10226", "This string cannot be converted to Double")
                        {ValueTypeCode = TypeCode.Double},    // here is the type explicitly specified
                    new UAWriteValueArguments(endpointDescriptor,
                        "nsu=http://test.org/UA/Data/ ;s=UnknownNode", "ABC")
                        {ValueTypeCode = TypeCode.String}    // here is the type explicitly specified
                });

            for (int i = 0; i < operationResultArray.Length; i++)
                if (operationResultArray[i].Succeeded)
                    Console.WriteLine($"Result {i}: success");
                else
                    Console.WriteLine($"Result {i}: {operationResultArray[i].Exception.GetBaseException().Message}");


            // Example output:
            //
            //Modifying values of nodes...
            //Result 0: success
            //Result 1: Input string was not in a correct format.
            //+ Attempting to change an object of type "System.String" to type "System.Double".
            //+ The specified original value (string) was "This string cannot be converted to Double".
            //+ The node descriptor used was: NodeId="nsu=http://test.org/UA/Data/ ;i=10226".
            //+ The client method called (or event/callback invoked) was 'WriteMultiple[3]'.
            //Result 2: OPC UA service result - {BadNodeIdUnknown}. The node id refers to a node that does not exist in the server address space.
            //+ The node descriptor used was: NodeId="nsu=http://test.org/UA/Data/ ;s=UnknownNode".
            //+ The client method called (or event/callback invoked) was 'WriteMultiple[3]'.
        }
    }
}
# This example shows how to write values into 3 nodes at once, specifying a type code explicitly. It tests for success of 
# each write and displays the exception message in case of failure.
#
# Reasons for specifying the type explicitly might be:
# - The data type in the server has subtypes, and the client therefore needs to pick the subtype to be written.
# - The data type that the reports is incorrect.
# - Writing with an explicitly specified type is more efficient.
#
# Alternative ways of specifying the type are using the ValueType or ValueTypeFullName properties.

#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 "Modifying values of nodes..."
$operationResultArray = $client.WriteMultipleValues([UAWriteValueArguments[]]@(
        (New-Object UAWriteValueArguments($endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10221", 23456) `
            -Property @{ValueTypeCode = [TypeCode]::Int32}), # here is the type explicitly specified
        (New-Object UAWriteValueArguments($endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10226", 
            "This string cannot be converted to Double") `
            -Property @{ValueTypeCode = [TypeCode]::Double}), # here is the type explicitly specified
        (New-Object UAWriteValueArguments($endpointDescriptor, "nsu=http://test.org/UA/Data/ ;s=UnknownNode", "ABC") `
            -Property @{ValueTypeCode = [TypeCode]::String}) # here is the type explicitly specified
    ))

for ($i = 0; $i -lt $operationResultArray.Length; $i++) {
    if ($operationResultArray[$i].Succeeded) {
        Write-Host "Result $($i): success"
    }
    else {
        Write-Host "Result $($i): $($operationResultArray[$i].Exception.GetBaseException().Message)"
    }
}


# Example output:
#
#Modifying values of nodes...
#Result 0: success
#Result 1: Input string was not in a correct format.
#+ Attempting to change an object of type "System.String" to type "System.Double".
#+ The specified original value (string) was "This string cannot be converted to Double".
#+ The node descriptor used was: NodeId="nsu=http://test.org/UA/Data/ ;i=10226".
#+ The client method called (or event/callback invoked) was 'WriteMultiple[3]'.
#Result 2: The status of the OPC-UA attribute data is not Good. The actual status is 'BadNodeIdUnknown'.
#+ During writing or method calls, readings may occur when value type is not specified.
#+ The node descriptor used was: NodeId="nsu=http://test.org/UA/Data/ ;s=UnknownNode".
#+ The client method called (or event/callback invoked) was 'WriteMultiple[3]'.
# This example shows how to write values into 3 nodes at once, specifying a type code explicitly. It tests for success
# of each write and displays the exception message in case of failure.
#
# Reasons for specifying the type explicitly might be:
# - The data type in the server has subtypes, and the client therefore needs to pick the subtype to be written.
# - The data type that the reports is incorrect.
# - Writing with an explicitly specified type is more efficient.
#
# Alternative ways of specifying the type are using the ValueType or ValueTypeFullName properties.

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

# Import .NET namespaces.
from System import *
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()

print('Modifying values of nodes...')
writeValueArguments1 = UAWriteValueArguments(endpointDescriptor,
                                             UANodeDescriptor('nsu=http://test.org/UA/Data/ ;i=10221'), 23456)
writeValueArguments1.ValueTypeCode = TypeCode.Int32 # here is the type explicitly specified
writeValueArguments2 = UAWriteValueArguments(endpointDescriptor,
                                             UANodeDescriptor('nsu=http://test.org/UA/Data/ ;i=10226'),
                                             'This string cannot be converted to Double')
writeValueArguments2.ValueTypeCode = TypeCode.Double # here is the type explicitly specified
writeValueArguments3 = UAWriteValueArguments(endpointDescriptor,
                                             UANodeDescriptor('nsu=http://test.org/UA/Data/ ;s=UnknownNode'),
                                             'ABC')
writeValueArguments3.ValueTypeCode = TypeCode.String # here is the type explicitly specified

writeResultArray = IEasyUAClientExtension.WriteMultipleValues(client,
    [writeValueArguments1, writeValueArguments2, writeValueArguments3])

for i, writeResult in enumerate(writeResultArray):
    if writeResult.Succeeded:
        print('writeResultArray[', i, ']: success', sep='')
    else:
        print('writeResultArray[', i, '] *** Failure: ', writeResult.Exception.GetBaseException().Message, sep='')

print()
print('Finished.')
' This example shows how to write values into 3 nodes at once, specifying a type code explicitly. It tests for success of 
' each write and displays the exception message in case of failure.
'
' Reasons for specifying the type explicitly might be:
' - The data type in the server has subtypes, and the client therefore needs to pick the subtype to be written.
' - The data type that the reports is incorrect.
' - Writing with an explicitly specified type is more efficient.
'
' Alternative ways of specifying the type are using the ValueType or ValueTypeFullName properties.

Imports System
Imports OpcLabs.BaseLib.OperationModel
Imports OpcLabs.EasyOpc.UA
Imports OpcLabs.EasyOpc.UA.OperationModel

Namespace _EasyUAClient
    Partial Friend Class WriteMultipleValues
        Public Shared Sub ValueTypeCode()

            ' 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()

            ' Modify value of a node
            Dim operationResultArray() As OperationResult = client.WriteMultipleValues(New UAWriteValueArguments() _
                { _
                    New UAWriteValueArguments(endpointDescriptor, _
                        "nsu=http://test.org/UA/Data/ ;i=10221", 23456) _
                        With {.ValueTypeCode = TypeCode.Int32}, _
                    New UAWriteValueArguments(endpointDescriptor, _
                        "nsu=http://test.org/UA/Data/ ;i=10226", "This string cannot be converted to Double") _
                        With {.ValueTypeCode = TypeCode.Double}, _
                    New UAWriteValueArguments(endpointDescriptor, _
                        "nsu=http://test.org/UA/Data/ ;s=UnknownNode", "ABC") _
                        With {.ValueTypeCode = TypeCode.String} _
                } _
             )

            For i As Integer = 0 To operationResultArray.Length - 1
                If operationResultArray(i).Succeeded Then
                    Console.WriteLine("Result {0}: success", i)
                Else
                    Console.WriteLine("Result {0}: {1}", i, operationResultArray(i).Exception.GetBaseException().Message)
                End If
            Next i
        End Sub
    End Class
End Namespace
// This example shows how to write values into 3 nodes at once, specifying a type code explicitly. It tests for success of
// each write and displays the exception message in case of failure.
//
// Reasons for specifying the type explicitly might be:
// - The data type in the server has subtypes, and the client therefore needs to pick the subtype to be written.
// - The data type that the reports is incorrect.
// - Writing with an explicitly specified type is more efficient.
//
// Alternative ways of specifying the type are using the ValueType or ValueTypeFullName properties.

class procedure WriteMultipleValues.ValueTypeCode;
var
  Arguments: OleVariant;
  Client: OpcLabs_EasyOpcUA_TLB._EasyUAClient;
  I: Cardinal;
  WriteResult: _UAWriteResult;
  WriteValueArguments1, WriteValueArguments2, WriteValueArguments3: _UAWriteValueArguments;
  Results: OleVariant;
begin
  WriteValueArguments1 := CoUAWriteValueArguments.Create;
  WriteValueArguments1.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';
  WriteValueArguments1.NodeDescriptor.NodeId.ExpandedText := 'nsu=http://test.org/UA/Data/ ;i=10221';
  WriteValueArguments1.Value := 23456;
  WriteValueArguments1.ValueTypeCode := TypeCode_Int32;    // here is the type explicitly specified

  WriteValueArguments2 := CoUAWriteValueArguments.Create;
  WriteValueArguments2.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';
  WriteValueArguments2.NodeDescriptor.NodeId.ExpandedText := 'nsu=http://test.org/UA/Data/ ;i=10226';
  WriteValueArguments2.Value := 'This string cannot be converted to Double';
  WriteValueArguments2.ValueTypeCode := TypeCode_Double;    // here is the type explicitly specified

  WriteValueArguments3 := CoUAWriteValueArguments.Create;
  WriteValueArguments3.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';
  WriteValueArguments3.NodeDescriptor.NodeId.ExpandedText := 'nsu=http://test.org/UA/Data/ ;s=UnknownNode';
  WriteValueArguments3.Value := 'ABC';
  WriteValueArguments3.ValueTypeCode := TypeCode_String;    // here is the type explicitly specified

  Arguments := VarArrayCreate([0, 2], varVariant);
  Arguments[0] := WriteValueArguments1;
  Arguments[1] := WriteValueArguments2;
  Arguments[2] := WriteValueArguments3;

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

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

  // Display results
  for I := VarArrayLowBound(Results, 1) to VarArrayHighBound(Results, 1) do
  begin
    WriteResult := IInterface(Results[I]) as _UAWriteResult;
    if WriteResult.Succeeded then
      WriteLn('Result ', I, ' success')
    else
      WriteLn('Result ', I, ': ', WriteResult.Exception.GetBaseException.Message);
  end;

  VarClear(Results);
  VarClear(Arguments);
end;
// This example shows how to write values into 3 nodes at once, specifying a type code explicitly. It tests for success of
// each write and displays the exception message in case of failure.
//
// Reasons for specifying the type explicitly might be:
// - The data type in the server has subtypes, and the client therefore needs to pick the subtype to be written.
// - The data type that the reports is incorrect.
// - Writing with an explicitly specified type is more efficient.
//
// Alternative ways of specifying the type are using the ValueType or ValueTypeFullName properties.

const TypeCode_Int32 = 9;
const TypeCode_Double = 14;
const TypeCode_String = 18;

$WriteValueArguments1 = new COM("OpcLabs.EasyOpc.UA.OperationModel.UAWriteValueArguments");
$WriteValueArguments1->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";
$WriteValueArguments1->NodeDescriptor->NodeId->ExpandedText = "nsu=http://test.org/UA/Data/ ;i=10221";
$WriteValueArguments1->Value = 23456;
$WriteValueArguments1->ValueTypeCode = TypeCode_Int32;    // here is the type explicitly specified

$WriteValueArguments2 = new COM("OpcLabs.EasyOpc.UA.OperationModel.UAWriteValueArguments");
$WriteValueArguments2->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";
$WriteValueArguments2->NodeDescriptor->NodeId->ExpandedText = "nsu=http://test.org/UA/Data/ ;i=10226";
$WriteValueArguments2->Value = "This string cannot be converted to Double";
$WriteValueArguments2->ValueTypeCode = TypeCode_Double;    // here is the type explicitly specified

$WriteValueArguments3 = new COM("OpcLabs.EasyOpc.UA.OperationModel.UAWriteValueArguments");
$WriteValueArguments3->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";
$WriteValueArguments3->NodeDescriptor->NodeId->ExpandedText = "nsu=http://test.org/UA/Data/ ;s=UnknownNode";
$WriteValueArguments3->Value = "ABC";
$WriteValueArguments3->ValueTypeCode = TypeCode_String;    // here is the type explicitly specified

$arguments[0] = $WriteValueArguments1;
$arguments[1] = $WriteValueArguments2;
$arguments[2] = $WriteValueArguments3;

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

// Modify values of nodes
$results = $Client->WriteMultipleValues($arguments);

// Display results
for ($i = 0; $i < count($results); $i++)
{
    $WriteResult = $results[$i];
    if ($WriteResult->Succeeded)
        printf("Result %d success\n", $i);
    else
        printf("Result  s \n", $i, $WriteResult->Exception->GetBaseException()->Message);
}
Rem This example shows how to write values into 3 nodes at once, specifying a type code explicitly. It tests for success of
Rem each write and displays the exception message in case of failure.
Rem
Rem Reasons for specifying the type explicitly might be:
Rem - The data type in the server has subtypes, and the client therefore needs to pick the subtype to be written.
Rem - The data type that the reports is incorrect.
Rem - Writing with an explicitly specified type is more efficient.
Rem
Rem Alternative ways of specifying the type are using the ValueType or ValueTypeFullName properties.

Public Sub WriteMultipleValues_ValueTypeCode_Command_Click()
    OutputText = ""

    Const TypeCode_Int32 = 9
    Const TypeCode_Double = 14
    Const TypeCode_String = 18

    ' Instantiate the client object
    Dim Client As New EasyUAClient

    Dim WriteValueArguments1 As New UAWriteValueArguments
    WriteValueArguments1.endpointDescriptor.UrlString = "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
    WriteValueArguments1.nodeDescriptor.NodeId.expandedText = "nsu=http://test.org/UA/Data/ ;i=10221"
    WriteValueArguments1.SetValue 23456
    WriteValueArguments1.ValueTypeCode = TypeCode_Int32    ' here is the type explicitly specified

    Dim WriteValueArguments2 As New UAWriteValueArguments
    WriteValueArguments2.endpointDescriptor.UrlString = "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
    WriteValueArguments2.nodeDescriptor.NodeId.expandedText = "nsu=http://test.org/UA/Data/ ;i=10226"
    WriteValueArguments2.SetValue "This string cannot be converted to Double"
    WriteValueArguments2.ValueTypeCode = TypeCode_Double    ' here is the type explicitly specified

    Dim WriteValueArguments3 As New UAWriteValueArguments
    WriteValueArguments3.endpointDescriptor.UrlString = "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
    WriteValueArguments3.nodeDescriptor.NodeId.expandedText = "nsu=http://test.org/UA/Data/ ;s=UnknownNode"
    WriteValueArguments3.SetValue "ABC"
    WriteValueArguments3.ValueTypeCode = TypeCode_String    ' here is the type explicitly specified

    Dim arguments(2) As Variant
    Set arguments(0) = WriteValueArguments1
    Set arguments(1) = WriteValueArguments2
    Set arguments(2) = WriteValueArguments3

    ' Modify values of nodes
    Dim results As Variant
    results = Client.WriteMultipleValues(arguments)

    ' Display results
    Dim i: For i = LBound(results) To UBound(results)
        Dim Result As UAWriteResult: Set Result = results(i)
        If Result.Succeeded Then
            OutputText = OutputText & "Result " & i & " success" & vbCrLf
        Else
            OutputText = OutputText & "Result " & i & ": " & Result.Exception.GetBaseException().Message & vbCrLf
        End If
    Next
End Sub
Requirements

Target Platforms: .NET Framework: Windows 10 (selected versions), Windows 11 (selected versions), Windows Server 2016, Windows Server 2022; .NET: Linux, macOS, Microsoft Windows

See Also