On Thu, 19 Nov 1998, Basham, Richard R wrote:
> In case some of you do not know anything about LabView, it is a graphical
> language. It allows the "programmer" to attach icons, that define
> functions, together to create a program. I am a tried and true C programmer
> myself and believe that it is a better language. However, LabView has one
> standout quality. It has the ability to let the "programmer" build nice
> looking graphical user interfaces. It is a fast easy way of producing data
> displays with graphs, thermometers, gauges, buttons, etc. What I have found
> is that for my applications, 1 ms periods and better, it does not perform
> well by itself. However, combined with RT-Linux I think it can be a very
> useful tool. I do not have it myself. I plan on purchasing it soon. If
> there are others out there who have been using it or are planning on using
> it, I would like to here your reviews.
LabVIEW is a good hook for some beginners that need to get something done
quickly; it is, in a sense, the "Visual Basic" of data acquistion and
instrument control. I would say its performance is poor and unsuitable for
real-time tasks requiring sub-Hz periods (this has a lot to do with the
fact that I have run it on Windows systems (i.e. 95/NT) which are not
really suitable for real-time work with a short period). The Linux version
could be coupled to an RT-Linux task through a custom C-interface module,
so I guess it could make a reasonable, albeit expensive, front end.
I have used it for a few straight acquisition projects and found that it
was just 'ok' - I did not find graphical programming to be faster or
better than C (especially if it was used to read older binary data files
- I found building "structures" somewhat painful), and you lose easily
parsed text. I also did not find that it was easy enough for
non-programmers to use, which was an initial selling point. Programming is
a skill in itself, the tools don't create programmers from non-programmers
no matter how pretty they are.
The graphical controls, or widgets, are quite pretty though; I have used
the NI Component Works library on NT/95 just to get those pretty widgets.
There has been talk recently on the llp list and elsewhere of building a
better LabVIEW-like (but non-graphical) system for Linux. I believe Tcl/Tk
was being thrown about as the top-level programming interface.
> If there are other easy to use graphical display builders or libraries out
> there I would like to know.
Many projects given here have used the much ballyhooed Qt library from
http://www.troll.no/ - this library is used in some example programs from
Victor Yodaiken's lab (Bill Crum's examples?), I believe, and David
Christini employed it as well. It is very nice. Qt is now sort of open
source, and free for non-commercial software, it is the basis of the KDE
project.
I have taken to using FLTK (fltk.easysw.com) which is LGPL'd and cross-
platform between Win9X/NT, Linux, and SGI. It has a few nice widgets
(look at the 'valuators' - especially the roller), and is under active
development. It's big advantages are in its OpenGL support and the fact
that it is a small static library - the execs are small and distribution
is mindless.
Other folks on llp have used Tk with BLT to handle the GUI
(http://www.scriptics.com/).
None of these toolkits contain the variety of pretty widgets from National
Instruments. On the upside, all of them are open source in one sense or
another, so there is less of a problem with vendor lock-in or
inflexibility. They are all cross-platform in some sense as well, although
Tk is the only solution which excels in this area (Qt will cost $$ to
move back to Windows and there is no Mac support; for FLTK, Mac support
is "in the works" but is not yet available).
My opinion on LabVIEW (and by extension Visual Basic) is that it is great
for small projects and prototyping. The downside (of both) is that they
are relatively difficult to interface with outside code, can be difficult
to maintain as projects grow, and they lock you in to a proprietary
technology. You say that there is an educational discount for LabVIEW, but
my copy of 4.0 still ran over $700.00, If I recall correctly, and to setup
the same code on all of the researchers' desks would cost a mint in
additional licenses. The runtime kit did not seem to be an attractive
option either. Either way, in the end, you pay.
-Don
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