Public Class Form1
    Dim WithEvents SerialPort1 As New IO.Ports.SerialPort()
    Dim input As String
    Dim buf As Byte()
    Private Delegate Sub DelegateSub()
    Private txtactualise As New DelegateSub(AddressOf exchange)
 
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles MyBase.Load
        With SerialPort1
            If .IsOpen Then
                .Close()
            End If
            .PortName = "COM1"
            .BaudRate = 9600
            .Parity = IO.Ports.Parity.Even
            .DataBits = 7
            .StopBits = IO.Ports.StopBits.One
            'Port öffnen
            .Open()
            Return
        End With
    End Sub
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button1.Click
        End
    End Sub
 
    Private Sub SerialPort1_DataReceived(ByVal sender As System.Object, ByVal e _
      As System.IO.Ports.SerialDataReceivedEventArgs) Handles _
      SerialPort1.DataReceived
        input = SerialPort1.ReadLine
        Me.Invoke(txtactualise)
    End Sub
 
    Private Sub exchange()
        Label1.Text = input
    End Sub
End Class