WriteItem(IEasyDAClient,ServerDescriptor,DAItemDescriptor,DAVtq) Method

Writes into a named item in an OPC server. Value, quality and timestamp are written. Writes DAVtq into a named item using descriptor objects for the OPC server and OPC-DA item.

Syntax

Visual Basic
C#
C++/CLI

'Declaration
 
<ExtensionAttribute()>
Public Overloads Shared Sub WriteItem( _
   ByVal client As IEasyDAClient, _
   ByVal serverDescriptor As ServerDescriptor, _
   ByVal itemDescriptor As DAItemDescriptor, _
   ByVal vtq As DAVtq _
)

'Usage
 
Dim client As IEasyDAClient
Dim serverDescriptor As ServerDescriptor
Dim itemDescriptor As DAItemDescriptor
Dim vtq As DAVtq
 
IEasyDAClientExtension.WriteItem(client, serverDescriptor, itemDescriptor, vtq)

[Extension()]
public static void WriteItem( 
   IEasyDAClient client,
   ServerDescriptor serverDescriptor,
   DAItemDescriptor itemDescriptor,
   DAVtq vtq
)

[Extension()]
public:
static void WriteItem( 
   IEasyDAClient^ client,
   ServerDescriptor^ serverDescriptor,
   DAItemDescriptor^ itemDescriptor,
   DAVtq^ vtq
)

Parameters

client: The client object that will perform the operation.
serverDescriptor: The OPC server involved in the operation.
itemDescriptor: The OPC item involved in the operation.
vtq: The object containing the value, timestamp and quality to be written.

Exceptions

Exception	Description
OpcLabs.EasyOpc.OperationModel.OpcException	Thrown when the OPC operation fails.
System.ArgumentNullException	A `null` reference (`Nothing` in Visual Basic) is passed to a method that does not accept it as a valid argument.

Remarks

The server can be local or can be remotely accessed via DCOM. Optionally, an access path can be specified or a specific data type can be requested.

Example

CSharp
Object Pascal
VBScript

// This example shows how to write a value, timestamp and quality into a single item.

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

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

            try
            {
                client.WriteItem("", "OPCLabs.KitServer.2", "Simulation.Register_I4", 
                    12345, DateTime.SpecifyKind(new DateTime(1980, 1, 1), DateTimeKind.Utc), 192);
            }
            catch (OpcException opcException)
            {
                Console.WriteLine($"*** Failure: {opcException.GetBaseException().Message}");
                return;
            }
            Console.WriteLine("Success");
        }
    }
}

// This example shows how to write a value, timestamp and quality into a single item.

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

  try
    Client.WriteItem('', 'OPCLabs.KitServer.2', 'Simulation.Register_I4', 12345, EncodeDate(1980, 1, 1), DAQualities_GoodNonSpecific);
  except
    on E: EOleException do
    begin
      WriteLn(Format('*** Failure: %s', [E.GetBaseException.Message]));
      Exit;
    end;
  end;

end;

Rem This example shows how to write a value, timestamp and quality into a single item.

Option Explicit

Dim Client: Set Client = CreateObject("OpcLabs.EasyOpc.DataAccess.EasyDAClient")
On Error Resume Next
Client.WriteItem "", "OPCLabs.KitServer.2", "Simulation.Register_I4", 12345, DateSerial(1980, 1, 1), 192
If Err.Number <> 0 Then
    WScript.Echo "*** Failure: " & Err.Source & ": " & Err.Description
    WScript.Quit
End If
On Error Goto 0

Requirements

Target Platforms: .NET Framework: Windows 10 (selected versions), Windows 11 (selected versions), Windows Server 2012, Windows Server 2016; .NET Core, .NET 5, .NET 6: Linux, macOS, Microsoft Windows

Reference

IEasyDAClientExtension Class
IEasyDAClientExtension Members
Overload List