Is it possible to read/write tags in kepserver using VB.NET application?

Question

We are using following document for creating a VB.NET windows application to communicate with KepServerEx.

Title: ClientAce: Creating a Simple Windows Form Application

https://www.kepware.com/getattachment/66dac2e9-1496-4b22-9301-454e506a5ca6/clientace-simple-windows-form-application.pdf

Using the above document, we could successfully read data from KepServerEx.

However we also want to send the data inputted in VB.NET application back to the KepServerEx. Is this possible?

Answer 1

Solved by using following code -

"Kepware.ClientAce.OpcDaClient.DaServerMgt.Write(itemIdentifiers, OPCWriteValue)"

where -

itemIdentifiers(n)

• Kepware.ClientAce.OpcDaClient.ItemIdentifier
• contains tags definition

OPCWriteValue(n)

• Kepware.ClientAce.OpcDaClient.ItemValue
• contains tag values

Full code below:

Imports Kepware.ClientAce    

Public Class Form1
    Inherits System.Windows.Forms.Form

    Dim maxAge As Integer = 0
    Dim WithEvents daServerMgt As New Kepware.ClientAce.OpcDaClient.DaServerMgt
    Dim activeClientSubscriptionHandle As Integer
    Dim activeServerSubscriptionHandle As Integer
    Dim itemIdentifiers(1) As Kepware.ClientAce.OpcDaClient.ItemIdentifier
    Dim itemValues(1) As Kepware.ClientAce.OpcDaClient.ItemValue
    Dim OPCWriteValue(1) As Kepware.ClientAce.OpcDaClient.ItemValue

    Private Sub Form1_Load(sender As Object, e As System.EventArgs) Handles Me.Load

        Dim url As String
        url = "opcda://localhost/Kepware.KEPServerEX.V6"
        Dim clientHandle As Integer
        clientHandle = 1

        Dim connectInfo As New Kepware.ClientAce.OpcDaClient.ConnectInfo
        connectInfo.ClientName = "OPC UA Test Client"
        connectInfo.LocalId = "en"
        connectInfo.KeepAliveTime = 60000
        connectInfo.RetryAfterConnectionError = True
        connectInfo.RetryInitialConnection = False
        Dim connectFailed As Boolean
        connectFailed = False

        itemIdentifiers(0) = New Kepware.ClientAce.OpcDaClient.ItemIdentifier
        itemIdentifiers(0).ItemName = "Channel1.Device1.Tag1"
        itemIdentifiers(0).ClientHandle = 0
        itemIdentifiers(0).DataType = Type.GetType("System.Int16")

        itemIdentifiers(1) = New Kepware.ClientAce.OpcDaClient.ItemIdentifier
        itemIdentifiers(1).ItemName = "Channel1.Device1.Tag2"
        itemIdentifiers(1).ClientHandle = 1
        itemIdentifiers(1).DataType = Type.GetType("System.Int16")

        Try
            daServerMgt.Connect(url, clientHandle, connectInfo, connectFailed)
    
        Catch ex As Exception
            MsgBox("Handled Connect exception. Reason: " & ex.Message)

            ' Make sure following code knows connection failed:
            connectFailed = True

        End Try

        Dim clientSubscriptionHandle As Integer = 1
        Dim active As Boolean = True
        Dim updateRate As Integer = 1000
        Dim deadBand As Single = 0
        Dim revisedUpdateRate As Integer

        Try
            daServerMgt.Subscribe(clientSubscriptionHandle, active, updateRate, revisedUpdateRate, deadBand, itemIdentifiers, activeServerSubscriptionHandle)

            ' Handle result:

            ' Save the active client subscription handle for use in 
            ' DataChanged events:
            activeClientSubscriptionHandle = clientSubscriptionHandle

            ' Check item result ID:
            For itemIndex = 0 To 1
                If itemIdentifiers(itemIndex).ResultID.Succeeded = False Then

                    ' Show a message box if an item could not be added to subscription.
                    ' You would probably use some other, less annoying, means to alert
                    ' the user to failed item enrolments in an actual application. 
                    MsgBox("Failed to add item " & itemIdentifiers(itemIndex).ItemName & " to subscription")
                End If
            Next

        Catch ex As Exception
            MsgBox("Handled Subscribe exception. Reason: " & ex.Message)
        End Try

        Try

            daServerMgt.Read( _
            maxAge, _
            itemIdentifiers, _
            itemValues)

            ' Handle results

            Dim item As Integer

            For item = 0 To 1

                If itemIdentifiers(item).ResultID.Succeeded = True Then

                    Console.WriteLine( _
                    "Value: " & itemValues(item).Value & _
                    " Quality: " & itemValues(item).Quality.Name & _
                    " Timestamp: " & itemValues(item).TimeStamp)

                Else

                    Console.WriteLine("Read failed for item: " & _
                    itemIdentifiers(item).ItemName)

                End If

            Next

        Catch ex As Exception

            Console.WriteLine("Read exception. Reason: " & ex.Message)

        End Try

    End Sub

   Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
        OPCWriteValue(0) = New Kepware.ClientAce.OpcDaClient.ItemValue
        OPCWriteValue(0).Value = TextBox1.Text
        OPCWriteValue(1) = New Kepware.ClientAce.OpcDaClient.ItemValue
        OPCWriteValue(1).Value = TextBox2.Text
        Try
            daServerMgt.Write(itemIdentifiers, OPCWriteValue)
        Catch ex As Exception
            'Handle the write exception
            Console.WriteLine("Sync write failed with exception " & ex.Message)
        End Try

    End Sub

End Class