'letzte Dateneingabe  per Max ermitteln
                Dim letzteDateneingabe As Date = CDate(lastAblesedate) 'oder so 
                ' ähnlich
                Dim Heute As Date = CDate(Now)
                Dim Dauer_TotalMinuten = (Heute - _
                  letzteDateneingabe).TotalMinutes
                Dim Gesamtdauer As TimeSpan
                Gesamtdauer = TimeSpan.FromMinutes(Dauer_TotalMinuten)
 
                Label_letzteEingabeStrom.Text = String.Concat("letzte Eingabe" & _
                  "vor: " & _
                                                              String.Format( _
                                                              "{0:00}", _
                                                              Gesamtdauer.Total_
                                                              Days) & " Tagen")

Private Function FormatTimeSpan(ByVal time_span As TimeSpan, Optional ByVal _
  whole_seconds As Boolean = True) As String
    Dim txt As String = ""
 
    If time_span.Days > 0 Then
        txt &= ", " & time_span.Days.ToString() & " days"
        time_span = time_span.Subtract(New TimeSpan(time_span.Days, 0, 0, 0))
    End If
    If time_span.Hours > 0 Then
        txt &= ", " & time_span.Hours.ToString() & " hours"
        time_span = time_span.Subtract(New TimeSpan(0, time_span.Hours, 0, 0))
    End If
    If time_span.Minutes > 0 Then
        txt &= ", " & time_span.Minutes.ToString() & " " & "minutes"
        time_span = time_span.Subtract(New TimeSpan(0, 0, time_span.Minutes, 0))
    End If
 
    If whole_seconds Then
        ' Display only whole seconds.
        If time_span.Seconds > 0 Then
            txt &= ", " & time_span.Seconds.ToString() & " " & "seconds"
        End If
    Else
        ' Display fractional seconds.
        txt &= ", " & time_span.TotalSeconds.ToString() & " " & "seconds"
    End If
 
    ' Remove the leading ", ".
    If txt.Length > 0 Then txt = txt.Substring(2)
 
    ' Return the result.
    Return txt
End Function