I'm plotting data on the y-axis of a XY (scatter) chart, but I want to plot
it against time without the time looping back on itself, i.e. i want to have
the x-axis starting at midday on say the 18th of Feb and finishing at the
same time on the 19th of Feb. Is this possible?

At the moment the x-axis runs between midnight to midnight and doesn't
acknowledge the change of date so the data is being mixed up.