Bill Gatliff: > Karl Hammar wrote: > > Do anyone of you where the proper place to discuss open hardware is? > > I am going to start a project to replace plc's. > I've gone down this route many times. Never found the end, however. :) > > I would consider gEDA over kicad, it's more mature. But a somewhat > steeper learning curve, perhaps.
I'll check that out, thanks. > The main challenge isn't going to be the hardware, it's going to be the > programming environment. Lots of hardware can produce signals that look > like signals produced by PLCs, but those systems won't be as easy to > program as existing commercial PLCs without a pretty considerable > integration effort. For the moment I'm most interested of the hardware part. It should look like a plc, be rugged, and have exchangeable io-cards. I think I'll rule out single board systems and stacked systems like pc104. It should be easy to exchange io-cards, if possible hot-pluggable. Software is another project, but for now I'll do it in c. And I don't think I'll invest time to make it that plc-like. My main points is to make better hw that my current programs could run on. And in that sense it might be better to call it something else than open-plc. > If you do your job right, you'd be able to realize your "plc" hardware > as a PC with a USB-connected GPIO device, at least for some definitions > of "plc". And that would be a pretty interesting achievement in itself! Yes, I've thought about that, but I don't want to have a mess of usb-cables. I could use printed circuit usb lines, but spi looked more suited for the job. > The MatPLC software is one place you might look for the software > pieces. There are other examples, like EMC2, and so on. Google is > your friend here, for sure! > > This article is a little old, but might still be relevant: > > http://www.linuxjournal.com/article/1339 > > A communications stack, among countless others: > > http://www.ctiplcio.com/ > > The "beagleboard" would be a super-fast CPU, but with 1.8V i/o it would > need a daughtercard in order to make it useful. Cogent's CSB740 uses > the same CPU, but has a little friendlier 3.3V i/o. But neither comes > with any software stack to make it as programmable as a PLC. Both > support Linux already, however. I have looked at beagleboard, but it does not have ethernet. > Have fun! Yes I will! > http://www.linuxjournal.com/article/4603 > http://en.wikipedia.org/wiki/IEC_61131 Thanks for all the links. I'll put up some pages att http://aspodata.se/openhw/ when I have something to show. Regards, /Karl ----------------------------------------------------------------------- Karl Hammar Aspö Data [email protected] Lilla Aspö 148 Networks S-742 94 Östhammar +46 173 140 57 Computers Sweden +46 70 511 97 84 Consulting ----------------------------------------------------------------------- -- To UNSUBSCRIBE, email to [email protected] with a subject of "unsubscribe". Trouble? Contact [email protected]
