Fwd: Re: NI SCXI and E series boards

On Monday 14 October 2002 03:39 pm, Calin A. Culianu wrote:
> Greetings all,
>
> What do you guys/gals know about SCXI systems?  Namely, what's the idea?
> I understand it's some sort of signal-conditioning system that is
> software-configurable and that scales well to high channel counts.  Is
> that the case?  If so, how does one talk to the thing?  Do they make you
> use Windows drivers?  Is it some simple serial-line protocol any monkey
> can code up?  Or am I asking this in the wrong place?  I know I am lazy
> and should probably ask NI, but I know you guys are data acquisition and
> control geniuses, so I decided to ask you guys..  :)

Calin,

We use an SCXI chassis on our comedi daq systems with a lot of success.  I
 use the patch that Brad Keryan wrote for comedi 0.7.63 with some
 modifications to make it work with our own system.  I'd like to see it
 integrated into comedi, but in it's current state Dave didn't like how it
 was built (and I agree with him) and we never thought of a much better way
 of doing it.

Aside from that, I think of the modules as signal conditioning multiplexers.
We use them for thermocouple and pressure transducer measurements.  It
basically turns 4 of the DIO lines into serial data channels to communicate
with the SCXI box, and you are able to select which channel you want to
measure.  It basically puts the signal you select onto Analog Channel 0 and
then you measure it using a comedi_data_read.  That's strictly for analog in;
my experience is quite a bit less for analog out and anything digital, though
I assume they work very similiarly.

If you want to use linux, and need high channel counts or really good signal
conditioning, it's the way to go (in my opinion).  Especially if your budget
isn't all that tight - these modules can get quite pricy.

Caleb

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Received on 2002-10-14Z10:03:47