OPC Data Client - OPC DA - Using State Object When Subscribing to a Tag

Example code demonstrating how to bind a value to a form object using the State property in a subscription is shown below.

C#

 private void StateObjectExample_ItemChanged(object sender, OpcLabs.EasyOpc.DataAccess.EasyDAItemChangedEventArgs e)
 {
     try
     {
         //reference the state object passed from the subscription call, send value to placeholder object
         TextBox tb = (TextBox)e.State;

         //set textbox.text to the tag's returned value
         tb.Text = e.Vtq.Value.ToString();

     }
     catch (Exception ex)
     {
         MessageBox.Show("Error {0}", ex.ToString());
     }
 }

 private void Form1_Load(object sender, EventArgs e)
 {
     //Create the client object
     OpcLabs.EasyOpc.DataAccess.EasyDAClient StateObjectExample = new OpcLabs.EasyOpc.DataAccess.EasyDAClient();

     //assign the callback event to the OPC Client object
     StateObjectExample.ItemChanged += new System.EventHandler<OpcLabs.EasyOpc.DataAccess.EasyDAItemChangedEventArgs>(this.StateObjectExample_ItemChanged);

     //Subscribe to the tag, and pass the State Object (there is a text box object on the form in this example)
     StateObjectExample.SubscribeItem("127.0.0.1", "SWToolbox.TOPServer.V5", "Simulation Examples.Functions.User1", 100, textBox1);
 }

VB.NET

Public Class Form1

    Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
        '
        'Create an instance of the EasyDAClient object
        Dim EasyDAClient As New OpcLabs.EasyOpc.DataAccess.EasyDAClient
        '
        'Add the event handler for the ItemChanged event
        AddHandler EasyDAClient.ItemChanged, AddressOf EasyDAClient_ItemChanged
        '
        'Subscribe to the tag passing in: computer name, server name, tag name, scan rate,
        'and state object (i.e. object you want to bind the value to)
        EasyDAClient.SubscribeItem("", "SWToolbox.TOPServer.V5", "Channel1.Device1.Tag1", 1000, TextBox1)

    End Sub

    '
    'This is the callback event for the subscription
    Private Sub EasyDAClient_ItemChanged(sender As Object, e As OpcLabs.EasyOpc.DataAccess.EasyDAItemChangedEventArgs)


        'set the returned value property of the vtq equal to the textbox property of the state object
        'which in this example is a textbox on the form
        e.State.Text = e.Vtq.Value.ToString
    End Sub

End Class