Public Class Form1
    Dim readBuffer As String = ""
    Dim comOpen As Boolean
 
' automatisch vom Formdesigner generierter Code:
'----------------------------------------------------------------------
    Private Sub InitializeComponent()
        Me.SerialPort1 = New System.IO.Ports.SerialPort(Me.components)
    end sub
 
    Friend WithEvents SerialPort1 As System.IO.Ports.SerialPort
'-----------------------------------------------------------------------
 
'  eigener Code:
'-----------------------------------------------------------------------
  Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As _
    System.EventArgs) Handles MyBase.Load
 
        ' Geräteparameter setzen
        With SerialPort1
            .PortName = "COM2"
            .BaudRate = 9600
            .Parity = IO.Ports.Parity.None
            .DataBits = 8
            .StopBits = IO.Ports.StopBits.One
            .Handshake = IO.Ports.Handshake.None
            .RtsEnable = False
            .ReceivedBytesThreshold = 30
        End With
 
        ' prüfen, ob Gerät verfügbar ist:
        Try
            SerialPort1.Open()
 
        Catch ex As Exception
            comOpen = False
            MsgBox(ex.Message)
 
        End Try
 
 
        If Not comOpen And SerialPort1.IsOpen Then
            ' Gerät kann verwendet werden
            comOpen = True
        Else
            If (Not comOpen) Then GoTo skip
            comOpen = False
            MsgBox("COM2 nicht geöffnet!")
        End If
 
        skip:
        RxD_buffer.Text = "init"
        TxD_buffer.Text = "init"
 
    End Sub
 
End Class

mfg
Ellen