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

On Sat, Feb 11, 2006 at 11:35:30PM +0100, Daniel Nilsson wrote:
> I still however get error message after a few minutes of running my
> application: 
> 
> read failed while reading DAQ data: Broken pipe
> 
> 
> The kernel reports the following through dmesg:
> ni_mio_common: ai error a_status=e4f3
> 
> That is the only message from the kernel though. I know that while I
> was having buffer overflow problems the kernel driver did report
> buffer overflow which doesn't seem to be the case now. I don't know
> what this e4f3 status means, is there an error in my application (the
> way I use the card/drivers) or is there some other kind of problem?

Hi All,

I have done some more debugging on my problem, using the "scope"
application from comedi_examples. While running the scope application
at 10kHz sampling rate on 4 channels I get almost the same problem:

Scope reports:

scope: read: Broken pipe

and the kernel reports:

ni_mio_common: ai error a_status=e433

This happens after a while though, usually a few minuted of running
the application but sometimes longer. The PC is an Pentium Pro 200,
the card is a NI AT-MIO-16E-10 (ISA bus), driver version 0.7.69 and
kernel version is 2.6.8. The machine is diskless, root filesystem is
NFS mounted.

Based on the source for the kernel driver I come to the conclusion
that this is the FIFO buffer on the HW that is getting full. Since the
buffer is 512 bytes and I sample at 10kHz I calculated that the buffer
needs approximately 25.6ms to fill up (assuming 2 bytes per sample). I
seems like a long time to me taking into account that the HW will
interrupt the kernel to empty the buffer, which should take that long?

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 think the hardware is capable of doing DMA, but the driver doesn't
seem to be using that for some reason? Is it safe to assume DMA would
help this issue? Should I consider using RTlinux?

Best Regards
Daniel Nilsson

Received on 2006-02-13Z19:26:23