Module mdlDownload
 
    Private WithEvents MCl As Net.WebClient
    Private Timer1 As New System.Windows.Forms.Timer()
    Private BytesNew As Long
    Private BytesOld As Long
    Dim dt As New DataTable("tblBytes")
 
    ...
 
  Private Sub DownloadItem()
 
        MCl = New Net.WebClient
        MCl.DownloadFileAsync(New Uri(MBUrl), DownlFile)
 
        'Timer zum ermitteln der Downloadgeschwindigkeit
        AddHandler Timer1.Tick, AddressOf Timer1Events
        Timer1.Interval = 10000   '10sec für ruhigere Anzeige
        Timer1.Start()
 
        'Tabelle zum protokollieren
        dt.Columns.Add("new")
        dt.Columns.Add("old")
        dt.Columns.Add("diff")
        Form1.DataGridView1.DataSource = dt
        Form1.Show()
 
    End Sub
 
    Sub Timer1Events(ByVal myObject As Object, ByVal myEventArgs As EventArgs)
 
        Dim FileInf As FileInfo = New FileInfo(DownlFile)
        Dim dr As DataRow = dt.NewRow
 
        BytesNew = FileInf.Length
        Timer1.Stop()
 
        frmMain.lblSpeed.Text = String.Format("Übertragungsrate: {0:0.0}kB/s", ( _
          BytesNew - BytesOld) / 10240)
        frmMain.lblSpeed.Visible = True
 
        dr(0) = Math.Round(BytesNew / 10240, 1)
        dr(1) = Math.Round(BytesOld / 10240, 1)
        dr(2) = Math.Round(BytesNew / 10240, 1) - Math.Round(BytesOld / 10240, _
          1)
        dt.Rows.Add(dr)
 
        Timer1.Enabled = True
        BytesOld = FileInf.Length
 
    End Sub
...
End Module

 new     old     diff
 5783,6  5545,1  238,5
 5910,9  5783,6  127,3
 6042,8  5910,9  131,9
 6325,3  6042,8  282,5
 6611,7  6325,3  286,4