Dim currentDate As DateTime = Me.timepicker.Value
        Dim endDate As DateTime = currentDate.AddHours(9)
        Dim hCount As Integer = CInt(DateDiff(DateInterval.Hour, currentDate, _
          endDate))
        For i = 0 To hCount
            DataGridView1.Rows.Add(hCount, currentDate.AddHours(i).ToString( _
              "dd.MM.yyyy HH:mm"))
        Next

        Dim currentDate As DateTime = DateTime.Now
        Dim i As Double
        Dim delta As Double = 1.5
        Dim hCount As Integer = 5 'CInt(DateDiff(DateInterval.Hour, 
        ' currentDate, endDate))
 
        For i = 0 To hCount Step delta
            MessageBox.Show(currentDate.AddHours(i).ToString("dd.MM.yyyy" & _
              "HH:mm"))
        Next

        Dim dt As DataTable = DataSet1.Details
        '##########
        Dim currentDate As DateTime = timepicker.Value        'DateTime.Now
        Dim i As Double
        Dim delta As Double = 1.5
        Dim hCount As Integer = 10 'CInt(DateDiff(DateInterval.Hour, 
        ' currentDate, endDate))
 
        For i = 0 To hCount Step delta
            Dim NewRow As DataRow = dt.NewRow
 
            NewRow("Tagesdatum") = currentDate.AddHours(i).ToString("dd.MM.yyyy" & _
              "HH:mm")
            NewRow("Kommentar") = "das funzt-------"
            dt.Rows.Add(NewRow)
        Next
 
 
 
        DetailsDataGridView.Refresh()

        Dim d As DateTime = DateTime.Now
        Dim td As TimeSpan = TimeSpan.FromHours(1.5)
        MessageBox.Show(d.ToShortTimeString)
        d = d.Add(td)
        MessageBox.Show(d.ToShortTimeString)

        Dim currentDate As DateTime = DateTime.Now
        Dim lDate As New List(Of DateTime)
        Dim i As Double
        Dim delta As Double = 1.5
        Dim hCount As Integer = 5
 
 
        For i = 0 To hCount Step delta
            If lDate.Exists(Function(x) x = currentDate.AddHours(i)) = False _
              Then
                lDate.Add(currentDate.AddHours(i))
                MessageBox.Show(lDate.Item(lDate.Count - 1).ToString( _
                  "dd.MM.yyyy HH:mm"))
            End If
        Next
        For i = 0 To hCount + 2 Step delta
            If lDate.Exists(Function(x) x = currentDate.AddHours(i)) = False _
              Then
                lDate.Add(currentDate.AddHours(i))
                MessageBox.Show(lDate.Item(lDate.Count - 1).ToString( _
                  "dd.MM.yyyy HH:mm"))
            End If
        Next

   Dim dt As DataTable = DataSet1.Details1
        '##########
 
        Dim currentDate As DateTime = StartDate
        Dim currentEnde As DateTime = EndDate
 
        Dim delta As Double = nuddelta.Value
        Dim hCount As Integer = nudhcount.Value
 
        For i = 0 To hCount Step delta
            'prüfen
            'Pruefe Vorhandensein der Uhrzeit:
            Dim strPruefstring = currentDate.AddHours(i).ToString("HH:mm")
            If pruefe_Uhrzeit(strPruefstring) = False Then
 
                Fehler_Uhrzeit(strPruefstring)
            Else
                Dim NewRow As DataRow = dt.NewRow
                NewRow("Tagesdatum") = currentDate.ToString("dd.MM.yyyy HH:mm")
                NewRow("Uhrzeit") = currentDate.AddHours(i).ToString("HH:mm")
                NewRow("Kommentar") = ">"
 
                dt.Rows.Add(NewRow)
            End If
        Next

Private Function pruefe_Uhrzeit(ByVal strPruefstring As String) As Boolean
        Dim Anz = (From Eintrag In DataSet1.Details1
                   Where Eintrag.RowState <> DataRowState.Deleted AndAlso _
                     Eintrag.Uhrzeit.ToShortTimeString = strPruefstring.ToString
                   Select Eintrag).Count
 
        If Anz > 0 Then Return False
 
        Return True
    End Function

 ''' <summary>Ganze Stunde vor einem Zeitpunkt</summary>
    ''' <param name="dt">Zeitpunkt</param>
    Private Function FullHourBefore(ByVal dt As Date) As Date
        Return dt.Date.AddHours(dt.Hour)
    End Function
 
    ''' <summary>Liegen zwei Zeitpunkte innerhalb eines 
    ' Vergleichs-Intervalls</summary>
    ''' <param name="dt1">Erster Zeitpunkt</param>
    ''' <param name="dt2">Zweiter Zeitpunkt</param>
    ''' <param name="maxdiff">Intervall</param>
    Private Function AreDateTimesEqual(ByVal dt1 As Date, ByVal dt2 As Date, _
      maxdiff As TimeSpan) As Boolean
 
        If maxdiff < TimeSpan.Zero Then
            Throw New ArgumentException("Negative Schranke bei Zeitvergleich")
        End If
 
        Return New TimeSpan(Math.Abs(dt1.Ticks - dt2.Ticks)) <= maxdiff
    End Function
 
    ''' <summary>Erstellung einer Serie von gleichabständigen Zeitpunkten</summary>
    ''' <param name="dtStart">Startzeitpunkt</param>
    ''' <param name="dtEnd">Endzeitpunkt</param>
    ''' <param name="diff">Zeitintervall</param>
    Private Function GetTimeSeries(ByVal dtStart As Date, ByVal dtEnd As Date, _
      diff As TimeSpan) As List(Of Date)
 
        If diff <= TimeSpan.Zero Or
            dtStart >= dtEnd Then
            Throw New ArgumentException("Keine geeignete Parameterliste bei" & _
              "Zeitreihen-Erstellung")
        End If
 
        If Math.Abs(dtStart.Ticks - dtEnd.Ticks) \ Math.Abs(diff.Ticks) > _
          100 Then
            Throw New ArgumentException("Parameter definieren zu viele" & _
            "Zeitpunkte")
        End If
 
        Dim dt As Date = dtStart
        Dim dtList As New List(Of Date)
        dtList.Add(dtStart)
 
        Do Until dtEnd.Ticks < dt.Ticks + diff.Ticks
            dt = dt.Add(diff)
            dtList.Add(dt)
        Loop
 
        Return dtList
 
    End Function

    Dim NL As String = Environment.NewLine
        '--------------------------------------------------------------------
        Dim FirstDate As Date = CDate(dtp_start_Datetime.Value)
        Dim delta As Integer = CLng(nud_Sekunden.Value)
        Dim mCount As Integer = CInt(nud_mCount.Value)
 
        Dim Msg As String = Nothing
        Dim Daten As DataTable = DataSet1.Details
 
        For i = 1 To mCount
            FirstDate = DateAdd(DateInterval.Second, delta, FirstDate)
            If Daten.Select("Tagesuhrzeit = '" & FirstDate.ToString("dd.MM.yyyy" & _
              "HH:mm") & "'").Count = 0 Then
                ' Neue DRV
                Dim DR As DataRow = Daten.NewRow
                DR.Item("day") = FirstDate.ToString("ddd")
                DR.Item("Tagesdatum") = FirstDate.ToString("dd.MM.yyyy")
                DR.Item("Tagesuhrzeit") = FirstDate.ToString("HH:mm")
                DR.Item("Kommentar") = ">"
                'Neue Zeile
                Daten.Rows.Add(DR)
                'Me.Validate()
                'DetailsBindingSource.EndEdit()
                'In Dataset speichern 
 
            Else
                'abbrechen
                DetailsBindingSource.CancelEdit()
 
            End If
        Next
 
        Me.DetailsBindingSource.Sort = "Tagesuhrzeit Asc"

    'Einige Benutzereingaben in Controls
    Dim dtp As New DateTimePicker
    dtp.Value = New DateTime(2023, 5, 10, 13, 12, 45)
 
    Dim nudMinutes As New NumericUpDown
    nudMinutes.Value = 90
 
    Dim nudCount As New NumericUpDown
    nudCount.Value = 15
 
    'Umwandlung der Eingaben in die erforderlichen DateTime-Werte
    Dim startdatetime As DateTime = FullHourBefore(dtp.Value) 'siehe oben
    Dim interval As New TimeSpan(0, CInt(nudMinutes.Value), 0)
    Dim enddatetime As DateTime =
        startdatetime.AddMinutes(CInt(nudCount.Value) * interval.TotalMinutes)
 
    'Erstellung der Zeitpunktliste (siehe oben)
    Dim datetimelist As List(Of DateTime) =
            GetTimeSeries(startdatetime, enddatetime, interval)
 
    'Datentabelle
    Dim dt As New DataTable
    Dim dtColumnname As String = "Zeitpunkt"
    dt.Columns.Add(dtColumnname, GetType(DateTime))
 
    'Zwei Zeilen mit Zeitpunkten eintragen
    Dim dr As DataRow, fs As String
    dr = dt.NewRow
    dr(dtColumnname) = datetimelist(5).AddSeconds(15)
    dt.Rows.Add(dr)
 
    dr = dt.NewRow
    dr(dtColumnname) = datetimelist(10).AddSeconds(-25)
    dt.Rows.Add(dr)
 
    'Datenliste in Datatable übertragen unter Beachtung der 
    'bereits vorhandenen Zeitpunkte und
    'einer Genauigkeit von +/- 30 Sekunden
    For i As Integer = 0 To datetimelist.Count - 1
        dr = dt.NewRow()
 
        'Filterstring für Vergleich / Zeitangaben in Hochkommas
        fs = dtColumnname & ">'" & datetimelist(i).AddSeconds(-30) &
        "' And " & dtColumnname & "<'" & datetimelist(i).AddSeconds(+30) & "'"
 
        If dt.Select(fs).Count = 0 Then
           dr(dtColumnname) = datetimelist(i)
           dt.Rows.Add(dr)
        End If
    Next i
 
    'Für die getrennte Anzeige von Datum und Uhrzeit 
    'wird eine zweite Spalte (Expression) erstellt
    dt.Columns.Add("Uhrzeit", GetType(DateTime), dtColumnname)
 
    bs.DataSource = dt  'Bindingsource für Datenbindung

 Private Sub dgv_CellFormatting(sender As Object, 
     e As DataGridViewCellFormattingEventArgs) Handles dgv.CellFormatting
 
     If e.ColumnIndex = 0 Then
        If Not IsDBNull(e.Value) Then
           e.Value = CDate(e.Value).ToString("dd.MM.yyyy")
           e.FormattingApplied = True
        End If
     ElseIf e.columnindex = 1 Then
        If Not IsDBNull(e.Value) Then
           e.Value = CDate(e.Value).ToString("hh:mm")
           e.FormattingApplied = True
        End If
     End If
End Sub

'Zwei Zeilen mit Zeitpunkten eintragen
        Dim dr As DataRow, fs As String
        dr = dt.NewRow
        dr(dtColumnname) = datetimelist(5).AddSeconds(15)
        dt.Rows.Add(dr)
 
        dr = dt.NewRow
        dr(dtColumnname) = datetimelist(10).AddSeconds(-25)
        dt.Rows.Add(dr)

    Private Sub dgv_CellFormatting(sender As Object, 
        e As DataGridViewCellFormattingEventArgs) Handles dgv.CellFormatting
 
        If e.ColumnIndex = 0 Then
            If Not IsDBNull(e.Value) Then
                e.Value = CDate(e.Value).ToString("dd.MM.yyyy")
                e.FormattingApplied = True
            End If
        ElseIf e.columnindex = 1 Then
            If Not IsDBNull(e.Value) Then
                e.Value = CDate(e.Value).ToString("t",
                System.Globalization.CultureInfo.GetCultureInfo("DE-de"))
                e.FormattingApplied = True
            End If
        End If
    End Sub