On Thu, 28 Jan 2010 22:28:45 -0800 Raymond Lillard <rlill...@sonic.net> wrote:
> 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 > Small world... --I'm also in Los Gatos, so if you want to give me a ring, contact me off list. I'm guessing GPIB would be over-kill for your situation? I've got one National Instruments GPIB card for Sun (sbus) and a second for x86 (ISA). I think I might even have a NI PCI GPIB card around here somewhere. I believe I have I GPIB/Ethernet and GPIB/Serial bridges. I've always thought it might be fun to write OpenBSD drivers for the NI cards. GPIB might be old, but it's extremely useful. >From what you wrote, I'd also guess you want to keep things *very* simple, so I doubt you'll be getting into driving lots of equipment in a manufacturing/test environment? --The only hint you gave to the contrary was the desire for DIN rail mounting? Depending on distance/environment requirements, serial can be a viable option for you, and is often less complex and less expensive than USB. -Jon
