Re: Problems with at-mio-16e-10

Hi All,

On Mon, Feb 13, 2006 at 03:03:10PM -0700, Jim Benson wrote:
> On Mon, 13 Feb 2006, Daniel Nilsson wrote:
> 
> > > > Should I expect to be able to sample at 10kHz using this card? How can
> > > > I figure out why the FIFO is not emptied?
> > > > 
> > > 
> > > I don't know...though a few years ago I was running a
> > > NI AT-MIO-16E-1 (yup the 16E-1) with a 450 MHz machine,
> > > with RTAI. My scan rate was 200 kHz with 4 channels. The
> > > 16E-1 however has a 8196 byte fifo. When I switched to
> > > the PCI version of the card, which does only have
> > > a 512 byte fifo, my 3 GHz machine with RTAI
> > > was not fast enough, until I went to DMA.
> > 
> > Hmm, discouraging... I need a faster machine then, or sample slower
> > (which is actually a possibility for me). New HW is a little too
> > expensive though for this little project of mine...
> 
> Please wait for advice from the real comedi experts before
> getting discouraged. If you haven't tried already, 
> you might try slowing it down and/or try sampling 
> fewer channels and see if the problem goes away.  

So I made a few more attempts to resolve this problem... I upgraded to
the latest kernel (2.6.15.4), the latest comedi drivers (from CVS as
of yesterday). That didn't make any difference that I could notice.

I also lowered the sampling rate to 1000Hz, but I still get the same
error from the scope application:

scope: read: Broken pipe

dmesg says:
ni_mio_common: ai error a_status=e4b3

I'm now running the card at 1/100 of it's capacity (1kHz versus
100kHz) sampling rate. I must be missing something, because if that
still is too fast I don't know how to get to a stable situation. The
FIFO buffer should now be full every 250ms which is a rather long time
ever for my old Pentium Pro 200 CPU. The scope application also seems
to be failing after about the same amount of time (a few minutes)
regardless of the sampling rate so I don't really think it has to do
with the kernel getting to many interupts per second. In fact, if I
sample with 1kHz the counter in /proc/interrupts isn't even increasing
while the card is running (it is though at 10kHz). 

Maybe it's hard to give solid advice on the cause, but maybe someone
could suggest a method of debugging this issue?

Thanks!
-- 
Daniel Nilsson

Received on 2006-02-17Z18:33:53