je suis en cours de réaliser une application en VB.NET qui doit communiquer avec un automate Siemens S7-1200 en TCP/IP, le probléme c'est que j'arrive ni garder une communication permanant, ni envoyer des requettes à automate

Imports System.Net, System.Text
Imports System.Net.Sockets
Imports System.IO
Public Class Form1
    Dim t As New TcpClient

    Dim m As New TcpClient
    Dim k As TcpListener
    Dim buffer() As Byte
    Dim pingresult1 As Boolean
    Public clientsocket = New TcpClient("192.168.0.4", 2000)
    Dim netStream As NetworkStream = clientsocket.GetStream()
    Dim bytes(clientsocket.ReceiveBufferSize) As Byte

    'cnx sub
    Sub connect(ByVal ip As String, ByVal port As Integer)
        Try
            t.Connect(ip, port)
            If t.Available Then
                MsgBox("connected")
            End If
        Catch ex As Exception
            System.Threading.Thread.Sleep(10000)
            connect(ip, port)
        End Try
    End Sub
    'CNX
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        If ComboBox1.Text.Length < 4 Then
            MsgBox("please enter a valid ip")
        Else
            connect(ComboBox1.Text, ComboBox2.Text)
            Button1.Text = "connected"
            Dim pingresult As String = My.Computer.Network.Ping(ComboBox1.Text, ComboBox2.Text)
            If pingresult = True Then
                Button1.Text = "connected"
            Else
                Button1.Text = "disconnected"
            End If
        End If
    End Sub