[FRPythoneers] Re: VB/Python article....

J. Wayde Allen wallen at its.bldrdoc.gov
Wed Jun 6 13:47:13 MDT 2001


On Wed, 6 Jun 2001, Ferdinand Schmid wrote:

> GPIB seems to be everywhere - at least in the high accuracy
> measurement business.

Yes, in the measurement instrumentation business where you want to control
a spectrum analyzer or retrieve a reading from a digital volt meter the
GPIB bus is the norm.  It is particularly common if you are working with
discrete pieces of equipment that can be assembled on the laboratory
bench.

However, in a certain sense the GPIB interface is starting to show some
signs of its age.  It is still very useful and effective, but it is no
longer new and exciting.  It also has some speed limitations so people
looking to do real-time data acquisition have to be careful.  For the
real-time folks, and those who are interested in a more integrated system
the VXI bus instruments start taking over.  I think there is some interest
in USB and possibly firewire too, but I'm not sure how serious people are
about implementing instrument control this way.

> Do you think it would be a reasonable effort to write a C
> wrapper for the C driver of GPIB interface cards to make those drivers
> work for Python applications?  Or could you even take advantage of those
> C driver kits directly from Python?

I think that this would be the most likely way to get instrument control
functionality into Python.  In fact, a while back Sean hooked me up with
Tim Hochberg <tim.hochberg at ieee.org> and Ken Koller
<kkoller at NewFocus.com>.  Maybe these guys are here on the list?  These
guys have written several wrapper programs that they have provided
me.  I just haven't had a chance to take a hard look at what they sent.

> It seems that C drivers are available for those cards - but again
> mostly for the Windows platform.  That's another rant I kept repeating
> for a long time now.

Yes, but there are a few possibilities.  The Linux Lab project, whose URL
I provided earlier, have developed a generic Linux driver, and National
Instruments finally did offer Linux drivers for their equipment:

http://digital.ni.com/public.nsf/3efedde4322fef19862567740067f3cc/da11427db450fdcb86256257005717d0?OpenDocument

Doesn't seem like it should be too hard to build a wrapper around these
pieces of code.  (Of course I've yet to successfully compile either of
these drivers on my machines.)

- Wayde
  (wallen at its.bldrdoc.gov)





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