In article <8F6A9898Caledainupnawaycom@192.168.1.7>,
nospam@nospam (Alex) wrote:
> ursb@my-deja.com wrote in <8k1con$hn6$1@nnrp1.deja.com>:
>
> >Using CVI5 and NIDAQ 6.51 on Win9X I try to generate a continous
> >waveform output on the analog output. One application is sending a
pulse
> >to flash a lamp (1% duty cycle).
> >We are observing a strange 'jitter' on the pulse width although
there
> >is no update from the program. The amount of change and its
'frequency'
> > depends on the system (PC, DAQ Card...). Strange enough it gets
worth
> >when there is no data acquisition at the same time.
> >Is there a proper solution to eliminate this problem?
> >Has anybody written a continous pulse generator using on board timers
> >with NIDAQ/CVI or LabView?
> >
>
> There are some considerations to be made when doing analog out (under
> LabVIEW) at least. It might be that you are observing the reset of the
> board since (under LabVIEW) you can set up acquisition at easy,
> internediate or advanced levels. Usually the easy/intermediate levels
can
> re-initalise the board or be basically doing a "once off" each loop
> iteration. Check out the examples on buffered analog out which is
> effectively what you are trying to achieve.
>
> Hope this helps (unlikely since you are using CVI, but ...)
>
> Alex.
>
> --
>
> Alexander C. Le Dain, PhD
> ICON Technologies Pty Ltd
> http://www.icon-tech.com.au
>
>
Alex,
I do use CVI , but it is much more a (Ni)DAQ problem, isn't it?
The problem was 'solved' (driven around) by using on board counter which
can be programmed and DO work on their own.
I use the analog output in various projects as waveform genberators. I
set the parameters, download the waveform data and set the output length
to infinite. To my understanding it should run then for ever and with no
glitches, jitter and things like. In reality the card seems to fetch
data from the PC regularely and this causes the mentioned problems.
With faster cards and PC's the problems are less visible.
Does buffered analog out help?
thanks
Urs
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