This needed a working sample, so I worked one up for you, based on List Pickers and sticking to measurement intervals that fit evenly into hours.
chart_by_HHMM.aia (6.8 KB)
The Time range List Pickers at the top are wired to keep the From Hours less than the To Hours.
The interval minutes choice is used to populate minute Elements in the List Pickers and in generating an Elements list for the data entry HH:MM List Picker.
That Elements List has all the HH:MM Labels for the graph, and is the foundation for determining the x value of any graph points, counting from 0.
Having the graph Labels pre-populated allows for gaps in the incoming data.