QuickOPC User's Guide and Reference
ItemDescriptor Property (DAItemArguments)
Example 



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OpcLabs.EasyOpcClassicCore Assembly > OpcLabs.EasyOpc.DataAccess.OperationModel Namespace > DAItemArguments Class : ItemDescriptor Property
Gets or sets the OPC item descriptor that is an argument to the operation.
Syntax
'Declaration
 
<DataMemberAttribute()>
Public Property ItemDescriptor As DAItemDescriptor
 
'Usage
 
Dim instance As DAItemArguments
Dim value As DAItemDescriptor
 
instance.ItemDescriptor = value
 
value = instance.ItemDescriptor
Example

.NET

// Shows how to write into multiple OPC items using a single method call, specifying their requested data types.

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

namespace DocExamples.DataAccess._EasyDAClient
{
    partial class WriteMultipleItemValues
    {
        public static void RequestedDataType()
        {
            // 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_I2", 12345) 
                        { ItemDescriptor = { RequestedDataType = VarTypes.I2}}, // <-- the requested data type
                    new DAItemValueArguments("", "OPCLabs.KitServer.2", "Simulation.Register_R4", 234.56)
                        { ItemDescriptor = { RequestedDataType = VarTypes.R4}}  // <-- the requested data type 
                });


            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);
                }
            }

            Console.WriteLine("Reading multiple item values...");
            ValueResult[] valueResultArray = client.ReadMultipleItemValues("OPCLabs.KitServer.2",
                new DAItemDescriptor[] { "Simulation.Register_I2", "Simulation.Register_R4" });

            for (int i = 0; i < valueResultArray.Length; i++)
            {
                Debug.Assert(valueResultArray[i] != null);
                Console.WriteLine("valueResultArray[{0}]: {1}", i, valueResultArray[i]);
            }
        }
    }
}
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