Re: Data acquisition in Octave

[Dotan Cohen]

2008/11/19 Olaf Till <address@hidden>:
> On Wed, Nov 19, 2008 at 12:04:21PM +0200, Dotan Cohen wrote:
>> Can Octave perform DAQ (data acquisition) directly from National
>> Instruments DAQ cards, as does MatLAB Simulink?
>>
>
> Data aquisition on Linux is mostly done (and should be done) with the
> so called Comedi drivers and the Comedi library. They have good
> support for National Instruments cards.
>
> AFAIK there is no general interface of Octave to Comedi as
> yet. However, since dynamically linked functions (in Oct-files) can be
> generated, you can integrate self-made C-code, which accesses the
> Comedi library, into such files and use them from Octave.
>
> Writing such C-code for Comedi is in fact not much more tedious than
> using Matlabs DAQ toolbox (I have done both) --- the amount of
> learning to use Comedilib is surely not much higher than that for
> using all features of the DAQ toolbox (and you need quite a few
> features for serious work). An exception is that you need to use some
> general Unix functions, e.g. 'select', if you work with Comedilib;
> that is where the effort is greater than with the DAQ toolbox. That is
> also where some general functions for use with Comedi would probably
> be worth making ... OTOH, I ran into a couple of bugs when I tried to
> achieve the equivalent functionality with Matlabs toolbox (with an
> adapter for 'Data Translation').
>
> I have a C function specialized on simultaneous AI and AO (possibly on
> multiple boards) with Comedilib, which can be used from an
> Oct-file. It has to get passed a C structure with configuration
> information, and pointers to callback-functions to produce/accept
> data. It is probably not general enough to be offered to Octave ...
>
> Olaf

Thank you for your informative post, Olaf. While Octave seems to be
good enough for my own use (Numerical Analysis course), I see that for
an experienced lab tech to switch to Octave would mean that he has to
learn DAQ from scratch, again.

-- 
Dotan Cohen

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