Changing sample rate during acquisition

[Lancer]

I need to programmatically change sample rate during acquisition: My application involves sampling at slow rate most of the time but during "region of interest" I need to change sampling rate to fast (close to max rate of board).

[AndrewM]

Hi,

There are two ways of going about doing this. The first, which is the easiest, is to use the easy I/O functions in the DAQ palette. You can run the Acquire Waveforms VI inside of a loop. By doing this, each time the loop runs, you can specify what your frequency is. This is not the most effient way of acquiring data.

The second method is explained in the link below. This is an example program that does exactly what you want. It uses the AO clock to clock the AI. This program is a little more complex, but it works well.

http://zone.ni.com/devzone/explprog.nsf/6c163603265406328625682a006ed37d/94f6ea3c2401ff61862565e2004c0154?OpenDocument

Andrew

[Ronald]

I think it's also possible to use the same (high) sample rate during your
complete acquisition, but in the case you need the 'slow' rate only take
from the array sample 0, 10, 20 etc. or any number you prefer.
In the end I think you want to make sure your computer doesn't have to work
that hard all the way, or if you want to save the data, it's not that big...
If I'm wrong, please tell me.

Ron@ld
Lancer schreef in berichtnieuws
506500000008000000DF570000-1027480788000@exchange.ni.com...
> I need to programmatically change sample rate during acquisition: My
> application involves sampling at slow rate most of the time but during
> "region of interest" I need to change sampling rate to fast (close to
> max rate of board).