Private Sub btnAufzeichnungStarten_Click(ByVal sender As System.Object, _
    ByVal e As System.EventArgs) Handles btnAufzeichnungStarten.Click
        Dim Str As FileStream
        If File.Exists(CurDir() & "\Datei.txt") Then
            Str = New FileStream(CurDir() & "\Datei.txt", FileMode.Truncate, _
              FileAccess.Write, FileShare.None)
        Else
            Str = New FileStream(CurDir() & "\Datei.txt", FileMode.CreateNew, _
              FileAccess.Write, FileShare.None)
        End If
 
        'If Str IsNot Nothing Then - Abfrage müsste überflüssig sein!
        Str.Close()
        Str = Nothing
        'End If
 
        Timer2.Enabled = True
    End Sub

    Private Sub Timer2_Tick(ByVal sender As System.Object, _
    ByVal e As System.EventArgs) Handles Timer2.Tick
        Dim StreamW As StreamWriter
        i = i + 1
        StreamW = File.AppendText(CurDir() & "\Datei.txt")
        StreamW.WriteLine(i & "," & Now & "," & shortWert)
        StreamW.Close()
    End Sub