/**
         * @brief RequestTimer start procedure.
         */
        private void StartTimer()
        {
            if (RequestTimer == null)
            {
                RequestTimer          = new Timer(config.SampleTime);
                RequestTimer.Elapsed += new ElapsedEventHandler(RequestTimerElapsed);
                RequestTimer.Enabled  = true;

                ChartHumid.ResetAllAxes();
                ChartPress.ResetAllAxes();
                ChartTemp.ResetAllAxes();
            }
        }
        //updates pressure chart
        private void UpdatePlotP(double t, double d)
        {
            LineSeries lineSeries = ChartPress.Series[0] as LineSeries;

            lineSeries.Points.Add(new DataPoint(t, d));

            if (lineSeries.Points.Count > config.MaxSampleNumber)
            {
                lineSeries.Points.RemoveAt(0);
            }

            if (t >= config.XAxisMax)
            {
                ChartPress.Axes[0].Minimum = (t - config.XAxisMax);
                ChartPress.Axes[0].Maximum = t + config.SampleTime / 1000.0;;
            }

            ChartPress.InvalidatePlot(true);
        }