How to make the x-Bottom scale fixed.

[Tavit]

Hi friends i have a problem with my Plotting program. I have a db in which i save the data i have acquired. Initially the db is empty with no values. I need to have a fixed time scale from 0 to 60 seconds. Now once i click the start acquisition button i have to start acquiring data from a external device and save it to the DB and plot it. Its real time plotting. so i have to plot as i acquire the data. But the x-bottom scale changes according to the amount of data present in the db.
example - If i have only 4 values acquired to the DB the scale is changed to [0 to 3]. It looks like the image i have attached named (3).

If have say 40 values are added to the db the scale is changed to 35. It looks like the image i have attached named (35)

I actually wanted the scale to stay fixed to 60 and the graph to grow from the initial value as the data keeps adding in the graph has to grow gradually.Some thing like the snapshot (60) i have attached.

what do i need to do so that the x-bottom scale is fixed and the data to be plotted with out changing the scale irrespective of the amount of data present in the DB like in the image named (60).


Thank You
Please looking forward for a reply.