Private Sub Timer1_Tick(ByVal sender As System.Object, _
    ByVal e As System.EventArgs) Handles Timer1.Tick
        Dim buf(0) As Byte
        'M90.0 = Lebensbit, wird zyklisch im OB1 auf True gesetzt
        res = dc.readBits(libnodave.daveFlags, 0, 720, 1, buf)
        If buf(0) = 1 Then
            buf(0) = 0
            res = dc.writeBits(libnodave.daveFlags, 0, 720, 1, buf)
            btnAbbau.Enabled = True
            txtVerbindung.Text = "OK"
            txtVerbindung.BackColor = Color.Lime
        Else
            btnAbbau.Enabled = False
            txtVerbindung.Text = "Beendet"
            txtVerbindung.BackColor = Color.Red
            dc.disconnectPLC()
            di.disconnectAdapter()
            libnodave.closePort(fds.rfd)
            fds.rfd = 0
            di = Nothing
            dc = Nothing
            Timer1.Enabled = False
        End If
    End Sub