Public Class Form1 
Sub SendSerialData(ByVal data As String) 
Using com1 As IO.Ports.SerialPort = _
My.Computer.Ports.OpenSerialPort("COM1", 9600, IO.Ports.Parity.None, 8, 1)
 
com1.Write(data)
End Using
End Sub
 
Function ReceiveSerialData() As String 
' Receive strings from a serial port.
Dim returnStr As String = ""
 
Using com1 As IO.Ports.SerialPort = _
My.Computer.Ports.OpenSerialPort("COM1")
Do
Dim Incoming As String = com1.ReadLine()
If Incoming Is Nothing Then
Exit Do
Else
returnStr &= Incoming & vbCrLf
End If
Loop
com1.Close()
End Using
 
Return returnStr
End Function
 
Private Sub Form1_Load (ByVal sender As System.Object, ByVal e As _
  System.EventArgs) Handles MyBase.Load
 
Dim Empfangenes As String
Dim Returnstr As String = ""
 
 
Do
 
 
ReceiveSerialData()
Empfangenes = Returnstr
If Returnstr = "" Then
TextEmpfang.Text = "nichts Empfangen"
Else
TextEmpfang.Text = Returnstr
 
End If
 
 
 
 
 
 
Loop
End Sub
 
Private Sub TextEmpfang_TextChanged (ByVal sender As System.Object, ByVal e As _
  System.EventArgs) Handles TextEmpfang.TextChanged
 
End Sub
 
Private Sub ButtSenden_Click (ByVal sender As System.Object, ByVal e As _
  System.EventArgs) Handles ButtSenden.Click
Dim Senden As String
Senden = TextEingabe.Text
SendSerialData(Senden)
End Sub
 
Private Sub ButtLöschen_Click (ByVal sender As System.Object, ByVal e As _
  System.EventArgs) Handles ButtLöschen.Click
TextEmpfang.Text = ""
 
End Sub
End Class