Also if you can go with serial, there are loads of cheap digital voltmeters with serial interfaces. A while back I got a bunch of Metex ME-11 meters for our workshop, which have a DB9 connector. They come with windows/DOS software but I suspect the interface is reasonably universal (or at least "basic"). There are a lot of utilities around to talk to these (eg http://home.arcor.de/magnos/linux/metex/metex.html) which would probably build ok on OpenBSD.
Of course you did say you needed to measure a few voltages, so with this you'd be limited by number of serial ports. Don't know if it would work for you, but it seemed like a possible option... On Fri, Jan 29, 2010 at 05:00:33PM +0100, Daniel Gracia Garallar wrote: > With a proto board and some skills, you could build a serial system with > a total cost around US$30, small enough to not even need a rail support. > > You could also try to hang on the I2C iface of your mainboard and add > you own devices, but if you're not so much into electronics... Go the > Arduino way; readily available, cheap as chips and infinite expansion > boards. > > Ralph Becker-Szendy escribis: > >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? > -- ------------------------------------------------------------------------- Graham Allan - I.T. Manager - al...@physics.umn.edu - (612) 624-5040 School of Physics and Astronomy - University of Minnesota -------------------------------------------------------------------------
