OPC Studio User's Guide and Reference
WriteMultipleItemValues Method (IEasyDAClient)
Example 



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OpcLabs.EasyOpcClassicCore Assembly > OpcLabs.EasyOpc.DataAccess Namespace > IEasyDAClient Interface : WriteMultipleItemValues Method
Array of argument objects for the operation.

The value of this parameter cannot be null (Nothing in Visual Basic).

The individual elements of the parameter value cannot be null (Nothing in Visual Basic).

Writes values into named items in an OPC server or OPC servers. Only the item values are written (qualities and timestamp are not written).
Syntax
'Declaration
 
<NotNullAttribute()>
Function WriteMultipleItemValues( _
   ByVal argumentsArray() As DAItemValueArguments _
) As OperationResult()
 
'Usage
 
Dim instance As IEasyDAClient
Dim argumentsArray() As DAItemValueArguments
Dim value() As OperationResult
 
value = instance.WriteMultipleItemValues(argumentsArray)

Parameters

argumentsArray
Array of argument objects for the operation.

The value of this parameter cannot be null (Nothing in Visual Basic).

The individual elements of the parameter value cannot be null (Nothing in Visual Basic).

Return Value

The function returns an array of OpcLabs.BaseLib.OperationModel.OperationResult objects. The indices of elements in the output array are the same as those in the input arrays.

This method never returns null (Nothing in Visual Basic).

The individual elements of the returned value are never null (Nothing in Visual Basic).

Exceptions
ExceptionDescription

A null reference (Nothing in Visual Basic) is passed to a method that does not accept it as a valid argument.

This is a usage error, i.e. it will never occur (the exception will not be thrown) in a correctly written program. Your code should not catch this exception.

Remarks

The size of the input array will become the size of the output array. The element positions (indices) in the output array are the same as in the input array.

This method does not throw an exception in case of OPC operation failures. Instead, the eventual exception related to each item is returned in Exception property of each returned OpcLabs.BaseLib.OperationModel.OperationResult element.

The server(s) can be local or can be remotely accessed via DCOM.

Optionally, a specific data type can be requested, or an access path can be specified (OPC DA 1.0 only).

 

This is a multiple-operation method. In a properly written program, it does not throw any exceptions. You should therefore not put try/catch statements or similar constructs around calls to this method. The only exceptions thrown by this method are for usage errors, i.e. when your code violates the usage contract of the method, such as passing in invalid arguments or calling the method when the state of the object does not allow it. Any operation-related errors (i.e. errors that depend on external conditions that your code cannot reliably check) are indicated in the result objects returned by the method. For more information, see Multiple-operation Methods and Do not catch any exceptions with asynchronous or multiple-operation methods.
Example
// 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 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.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, specifying their requested data types.
//
// 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.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]);
            }
        }
    }
}
// This example measures the time needed to write 2000 item values all at once, and in 20 groups by 100 items.
// Note that the writes will currently all fail, as we do not have the appropriate writeable items available.
//
// 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.Diagnostics;
using System.Threading;
using OpcLabs.BaseLib.OperationModel;
using OpcLabs.EasyOpc.DataAccess.OperationModel;
using OpcLabs.EasyOpc.DataAccess;

namespace DocExamples.DataAccess._EasyDAClient
{
    partial class WriteMultipleItemValues
    {
        const int NumberOfGroups = 100;
        const int ItemsInGroup = 20;
        private const int TotalItems = NumberOfGroups * ItemsInGroup;

        // Main method
        public static void TimeMeasurements()
        {
            // Make the measurements 10 times; note that first time the times might be longer.
            for (int i = 1; i <= 10; i++)
            {
                // Pause - we do not want the component to use the values it has in memory
                Thread.Sleep(2 * 1000);

                // Write all item values at once, and measure the time
                var stopwatch1 = new Stopwatch();
                stopwatch1.Start();
                WriteAllAtOnce();
                stopwatch1.Stop();
                Console.WriteLine("WriteAllAtOnce has taken (milliseconds): {0}", stopwatch1.ElapsedMilliseconds);

                // Pause - we do not want the component to use the values it has in memory
                Thread.Sleep(2 * 1000);

                // Write item values in groups, and measure the time
                var stopwatch2 = new Stopwatch();
                stopwatch2.Start();
                WriteInGroups();
                stopwatch2.Stop();
                Console.WriteLine("WriteInGroups has taken (milliseconds): {0}", stopwatch2.ElapsedMilliseconds);
            }
        }

        // Write all item values at once
        private static void WriteAllAtOnce()
        {
            // Instantiate the client object.
            var client = new EasyDAClient();

            // Create an array of arguments for all items
            var arguments = new DAItemValueArguments[TotalItems];
            int index = 0;
            for (int iLoop = 0; iLoop < NumberOfGroups; iLoop++)
                for (int iItem = 0; iItem < ItemsInGroup; iItem++)
                    arguments[index++] = new DAItemValueArguments(
                        "OPCLabs.KitServer.2",
                        String.Format("Simulation.Incrementing.Copy_{0}.Phase_{1}", iLoop + 1, iItem + 1),
                        0);

            // Perform the OPC write
            OperationResult[] operationResults = client.WriteMultipleItemValues(arguments);

            // Count successful results
            int successCount = 0;
            for (int iItem = 0; iItem < TotalItems; iItem++)
            {
                Debug.Assert(operationResults[iItem] != null);
                if (operationResults[iItem].Succeeded)
                    successCount++;
            }

            if (successCount != TotalItems)
                Console.WriteLine("Warning: There were some failures, success count is {0}", successCount);
        }

        // Write item values in groups
        private static void WriteInGroups()
        {
            var client = new EasyDAClient();

            int successCount = 0;
            for (int iLoop = 0; iLoop < NumberOfGroups; iLoop++)
            {
                // Create an array of item arguments for items in one group
                var arguments = new DAItemValueArguments[ItemsInGroup];
                for (int iItem = 0; iItem < ItemsInGroup; iItem++)
                    arguments[iItem] = new DAItemValueArguments(
                        "OPCLabs.KitServer.2",
                        String.Format("Simulation.Incrementing.Copy_{0}.Phase_{1}", iLoop + 1, iItem + 1),
                        0);

                // Perform the OPC write
                OperationResult[] operationResults = client.WriteMultipleItemValues(arguments);

                // Count successful results (totalling to previous value)
                for (int iItem = 0; iItem < ItemsInGroup; iItem++)
                {
                    Debug.Assert(operationResults[iItem] != null);
                    if (operationResults[iItem].Succeeded) successCount++;
                }
            }

            if (successCount != TotalItems)
                Console.WriteLine("Warning: There were some failures, success count is {0}", successCount);
        }
    }
}
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