Re: RT-Control questions

On Wed, Aug 07, 2002 at 08:11:12PM +0200, Dominic wrote:
> Are their sourcecode examples available on the
> internet?

https://cvs.comedi.org/cgi-bin/viewcvs.cgi/comedi_examples/comedi_examples.tar.gz?tarball=1

> I don't think I'll be able to achieve 200kHz in a 
> closed-loop control system

The main limitation is RTAI or RTLinux (actually, the PC
architecture), which sets a maximum usable control rate
of about 10-20 kHz.

> the NI-6035 is only
> capable of 10 kS/s ;-) analog output.

Although I have not tried it, AO on the 6035 should be just as
fast as other boards (500 kS/s), with one condition -- there's
no FIFO, so you have to write each sample at the time you want
it to be output.  These specs were written for Windows, and
that's about as good as Windows gets.  (I'd claim about the same
for user-space Linux.)  However, using RTAI or RTLinux, you
should be able to get consistent 10 kS/s or more, depending on
how much CPU time you want to waste on it.

>      Are there good reasons to use RTLINUX for new projects or
>      wouldn't it be better for our department to port the yet small
>      code amount to RTAI.

Port.  It's not difficult.



dave...

Received on 2002-08-07Z18:14:02