If I understand the question properly then I'm not sure that this problem
can be solved accurately.

For example, if I run the logger for 1 second then I expect to have
60 samples spaced at 16.7 mS apart.

If I run the logger for 1.4 seconds then I expect to have 60 samples
spaced at 23.3mS apart.

If I run the logger for 2 seconds then I expect to have 60 samples
spaced at 33.3mS apart.

etc

How could you maintain an even sampling rate to something that is not
constant? Time in this case.

If the operator can turn the logger off at ANY given time how could
there be 60 samples waiting for you when the logging interval was
never known?

If I start off with a 60 sample time frame of 100mS what is the next time
frame?  101mS, 110mS, 200.000054mS, double the first?

If I discard old samples that do not fit the current sample rate they are
lost forever, but I may need some of them to match a future sample
rate or I may not. It sounds like an exploding data base may form
here, with excruciating task of sorting it out on the fly.

Tony


Just when I thought I knew it all,
I learned that I didn't.