Re: start_src=TRIG_EXT and NI PCI 6035e --- fixed

From: Adam Weiss <adam_at_signal11.com> · Date: Tue, 1 Aug 2006 08:09:15 -0700 (PDT)

I got this working the way we thought it should, so I thought I'd follow
up to the list so it ends up in the archives:

I needed the lastest comedi and comedilib from CVS.  I also wasn't or-ing
in CR_EDGE.

Here's my command structure:

  cmd.flags = 0;

  cmd.start_src      = TRIG_EXT;
  cmd.start_arg      = NI_EXT_PFI_0 | CR_EDGE;

  cmd.scan_begin_src = TRIG_TIMER;
  cmd.scan_begin_arg = floor(1.0E9/freq);

  cmd.convert_src    = TRIG_TIMER;
  cmd.convert_arg    = 0;

  cmd.scan_end_src   = TRIG_COUNT;
  cmd.scan_end_arg   = nchans;

  if (nscans == 0) {
    cmd.stop_src   = TRIG_NONE;
    cmd.stop_arg   = 0;
  }
  else {
    cmd.stop_src   = TRIG_COUNT;
    cmd.stop_arg   = nscans;
  }

--adam

On Tue, 1 Aug 2006, Adam Weiss wrote:

>
> Hey Folks,
>
> Has anyone gotten start_src=TRIG_EXT to work with NI-PCI-6035e cards?
> We've been playing with it for a few days and haven't been getting the
> results we were expecting.
>
> Either our expectations are wrong, the code is wrong or something is wrong
> with our environment.
>
> We expect that when start_src=TRIG_EXT is used with comedi_command(), any
> subsequent calls to read() or select() would indicate that no data is
> available until a signal is received on the input specified by
> start_src_arg.
>
> In reality, when we attempt this, both read() will start returning samples
> and select() will indicate data is available even if nothing is plugged
> into the input.  We've even tried unplugging everything from the box and
> we still see this behavior.
>
> Is this behavior by design or is something going wrong here?
>
> If something is going wrong here, has anyone been able to get
> start_src=TRIG_EXT to work with NI-PCI-6035e cards?  (or any NI card for
> that matter?)
>
> I can dig up the docs and would be more than happy to hack on the driver
> if this functionality is buggy or not implemented.  (At first glance, it
> appears there is some code in ni_mio_common that deals with this)  But
> before I get too carried away, I want to make sure it really is supposed
> to work the way we think it does and whether or not there might be
> something wrong in our envrionment.  (ie: does it work for other people?)
>
> If anyone has any information to offer regarding this issue, I'd much
> appreciate it.
>
> Thanks!
>
> --adam
>
>
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