PowerChart Scroll Buttons

Can someone please help me with Power Chart.
I have a chart that is configured to open in realtime mode with unitOfTime 24 hours.
I would like to have a button that will that will scroll the chart back in time, to the value of the unitOfTime.
So if my UnitOfTime is set to 1 hour every time a press the button the chart will scroll back 1 hour.
I’m not sure were to start? I’m assuming I have to write to the RangeStartDate and RangeStopDate but not sure how I only write to the Hours of this value?

This is not how real time works, real time is last x time. You’ll need to use historical mode instead and then calc the dates