Ralph Becker-Szendy wrote:
For one of my OpenBSD machines, I need to be able to measure a few
analog voltages, and act on them in a control process. The requirements
are quite simple compared to typical data acquisition: I absolutely
need two voltage inputs, either 0-20V or 0-100mV; doesn't have to be
differential, acquisition can be slow (1s is fine), and resolution can
be as small as 10-12 bits (1% accuracy is more than good enough). A few
extra input channels, more accuracy/resolution, and a few digital IOs
wouldn't hurt, but are not necessary. DIN rail mounting and connection
breakout would be nice, but can be improvised.
On the software side, there will be OpenBSD, with ad-hoc monitoring and
control scripts. With a little programming and script-writing, I can
adapt anything that the OS can reasonably access.
Now come the issues: I can't use PCI cards, only external units, most
likely connected via USB (as Ethernet and serial are expensive or rare).
And it needs to have some software support under OpenBSD - a Windows-
or Linux-only solution doesn't work. And this application is not worth
spending thousands of $$$. For Windows and LabView, solutions are easy
to find (for example EMant300, DAQPodMX, a variety of Omega products).
Does anyone now of a solution that would work with OpenBSD?
Ralph,
http://www.netburner.com/embedded_control.html
The PK70 with the analog board will give you everything you
asked for and quite a bit more at a hardware cost of US$400.
This may be over-kill, and you will need to write a bit of
code to run on the PK70. You will also need to add a voltage
divider if you want to go the 20V route.
The development environment is GCC based but unfortunately
hosted on Windows :-(. I have rolled my own cross-compilers
for other NB products on Linux, OpenBSD would probably be
possible. The development environment is not needed once
you have downloaded your code to flash on the PK70.It is
probably not worth the trouble as your requirements are small,
even though it's hard to be productive while holding your nose
with one hand while typing with the other.
I am assuming this is a hobby project and your time is
free (as in beer).
I have been using products from this company in volume for
a decade. They are good guys with very solid products.
I have no financial interest in the Netburner company.
I notice you are local to me. Contact me by off-line by
email if you want to talk about it by phone.
Ray
