Public in_put As String
 
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
  System.EventArgs) Handles Button1.Click
 
    'SerialPort1 ist schon geöffnet und parametriert
 
    SerialPort1.Write(TextBox1.Text)
 
End Sub
 
'***********  Anfang: Thread zum auslesen der RS232 und schreiben in TextBox2   
' *******************
 
Private Delegate Sub Data()
Private Empfang As New Data(AddressOf Empf)
 
Private Sub SerialPort1_DataReceived(ByVal sender As Object, _
    ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) _
    Handles SerialPort1.DataReceived
 
    in_put = SerialPort1.ReadExisting
    Me.Invoke(Empfang)
 
End Sub
 
Private Sub Empf()
    TextBox2.Text = in_put
End Sub
 
'***********  Ende: Thread zum auslesen der RS232 und schreiben in TextBox2   
' *******************