Private WithEvents tmrFertig As New Timer
Private oText As String = ""
Private Sub TextBox1_TextChanged(ByVal sender As Object,ByVal e As _
  System.EventArgs)Handles TextBox1.TextChanged
   tmrFertig.Interval = 100 'muss entsprechend der Geschwindigkeit des Scanners 
   ' angepasst werden...
   tmrFertig.Enabled = True
End Sub
Private Sub tmrFertig_Tick(ByVal sender As Object,ByVal e As _
  System.EventArgs)Handles tmrFertig.Tick
  If TextBox1.Text <> "" Then
    If oText = TextBox1.Text Then
       tmrFertig.Enabled = False
       Speichern()
    End If
  End If
  oText = TextBox1.Text
End Sub
Sub Speichern()
        If IO.Directory.Exists("\My Documents\testordner\") = False Then
            IO.Directory.CreateDirectory("\My Documents\testordner\")
        End If
        Dim sr As New IO.StreamWriter("\My Documents\testordner\Barcodes.txt", _
          True)
        sr.WriteLine(TextBox1.Text)
        sr.Flush()
        sr.Close()
        TextBox1.Text = "" 'hab ich vergessen^^
End Sub