How do you calculate the count in before a cue start?

Question

Here's what I can't figure out.
I have a quicktime loaded and I need to start a cue at, let's say, 1:05:07:10. I want the tempo to be, oh, 120. I arbitrarily say - this will be measure 41 but it doesn't really matter, I just need my downbeat at that TC and the tempo to be correct.
So far so good. I have no problem doing this with Tempo operations. I lock the time code, assign it a measure (in this case 41) and have logic calculate a single tempo from 1:00:00:00 (measure 1) to the desired start.
Now here's my real question. How do I calculate 4 or 8 beats before 1:05:07:10 so I can have a count it at the correct tempo (120)?
So I'm wonder how some of y'all handle this situation.
Thanks

Answer 1

As long as you are in the Fetch call, all other calls to the Scope
driver will block until Fetch exits.  That's why the Abort doesn't
do anything.  You have two options:
  1) Use a finite timeout.  Obviously, you are running into
cases in which the trigger does not arrive, and want to exit
cleanly.  This is exactly what the timeout is for.
  2) Determine the acquisition state before calling fetch. 
If this is a finite, single-record acquisition, poll on acquisition
status and do not call fetch until the status is 1 (acquisition
complete).  If you're doing a finite, multi-record acquisition,
poll on the Fetch>>Records Done property and only fetch the
records that have completed.  If you're doing a continuous
acquisition, poll on the Fetch>>Points Done or Fetch>>Fetch
Backlog property and only fetch the number of points that have been
acquired.
There's no clean way to break the infinite timeout fetch without forcing LabVIEW to close.