Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
  System.EventArgs) Handles Button1.Click
        Try
            SerialPort1.PortName = TextBox1.Text
            SerialPort1.BaudRate = TextBox2.Text
            SerialPort1.Open()
            Button1.Enabled = False
            Button2.Enabled = True
            Button3.Enabled = True
        Catch ex As Exception
            MsgBox("Verbindungsfehler!")
        End Try
    End Sub
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    Private Sub Form1_FormClosing(ByVal sender As Object, ByVal e As _
      System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing
 
If SerialPort1.IsOpen = True Then
            SerialPort1.Close()
 
        End If
    End Sub
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    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button2.Click
 
SerialPort1.Write("50-01-00-00-00-00-00-00-00-00-00-00-00-00-00-00" & vbCr)
    End Sub
-------------------------------------------------------------------------------_
  ------
    Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As _
    System.EventArgs) Handles Button3.Click
 
SerialPort1.Write("50-02-55-55-55-00-00-00-00-00-00-00-00-00-00-00" & vbCr)
    End Sub
End Class