Simultaneous Buffered and Looped Acquisition

[jdubcarter@my-deja.com]

I'm a graduate student in Biomechanics at the University of
Washington. I'm running Labview 5.1 on a Windows NT box with a PCI-
6071E DAQ board. Using this board I will be taking in between 8 and 12
Analog signals.

I want to sample all the analog channels at around 40kHz using a
buffered acquisition, while simultaneously taking two of the signals
and computing the integral of one versus the other in real time using a
looped acquistion. I have been able to get each component working
independently, however, I haven't had any success running the buffered
acquisition and looped acquisition simultaneously. Can anyone help me
out with this dilemna?

Also, if I get these two operations running simultaneously I wou
ld like
to have them synchronized to start at the same time. If anyone can
offer some wisdom on that it would be greatly appreciated.

Cheers


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[Andrew Johnson]

jdubcarter@my-deja.com wrote:

> I want to sample all the analog channels at around 40kHz using a
> buffered acquisition, while simultaneously taking two of the signals
> and computing the integral of one versus the other in real time using a
> looped acquistion. I have been able to get each component working
> independently, however, I haven't had any success running the buffered
> acquisition and looped acquisition simultaneously. Can anyone help me
> out with this dilemna?
>
> Also, if I get these two operations running simultaneously I would like
> to have them synchronized to start at the same time. If anyone can
> offer some wisdom on that it would be greatly appreciated.

How are you storing the data you acquire? Initially into a circular
buffer, and th
en to disk? That's a lot of data at 40kHz for 8 - 12
channels...

But in a parallel loop, on the same diagram, you should be able to peel
off the two channels you need and perform the operations you need. Do
not try to do it inside the acquisition loop, let that loop run at its
fastest possible speed. In the second, slower loop, you can handle
display of you integrated data.

- andrew johnson, Berkeley CA