Re: non blocking read (fwd)

From: Manuel Perez <perez_at_esrf.fr> · Date: Thu, 20 Jun 2002 07:55:37 +0200 (MET DST)

Hi Dave

Thanks for your help,

> 
> On Wed, Jun 19, 2002 at 04:19:55PM +0200, Manuel Perez wrote:
> > I'm observing that comedi_get_front_count() return 0 bytes while the
> > acquisition is taking place.When this one is finished then 
> > comedi_get_front_count() return the full acquisition size in bytes.
> 
> Perhaps you're just noticing that most Comedi drivers have a
> default chunk size in the hundreds or thousands of bytes.
> 
Yes, further tests show that there is a 4KB buffer in the driver.

> > I put also a call to comedi_poll(...) before calling comedi_get_front_count()
> > but without change in the behavior.
> 
> Not every driver supports comedi_poll().
> 
I'm using ni_pcimio with a NI PCI-6025E board. Isn't there a way to "flush"
driver internal buffer to get available data at any moment without having
to wait for two thousand data?

This is mandatory for us as our acquisition is based on a slow (100Hz) 
external clock and therefore we need to know during the acquisition if
things are going on correctly by displaying current acquired data.

	manuel
> 
> 
> dave...
> 
> 
> 
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