On 5/24/2013 12:18 PM, andy pugh wrote: > On 24 May 2013 17:02, Chris Radek<ch...@timeguy.com> wrote: > > >> I thought it was a pin already. I had always thought (in my "it >> shouldn't be too hard..." way) that keying off that would be a way >> to make an external component that slaves two motors and fakes all >> the home signals etc. It'd be pretty horrible but possible. >> > I suggested it earlier as a way to check that two slaved axes were > acceptably in-synch. > One unpleasant scenario in the machine described is the failure of one > home-switch, but not the other. I suggested a component that would > panic if one axis was still searching more than a few mS after the > other had started latching, > > >> To maintain this separately, it'd be great if you want to make a new >> branch off v2.5_branch with this change. Buildbot will even build >> and package it for you (seb pointed me to "Sorting of..." on >> http://buildbot.linuxcnc.org/dev.html when I asked about this) >> > The advantage of this would be that it is a less-experimental branch > than master, and so probably OK for Jon to use on a customer machine? > >> I still hope to work on joint slaving at fest next month - I have >> the test hardware built and with jepler's help (a loaner 7i30 and >> 5i20) I should have the hardware to run it. >> > I was planning on also bringing my Mesa harware collection. Which is > fairly extensive. > > >> I think that is the >> real and permanent answer. It's easy to hook two steppers together >> but to get index homing we really need to sort out how it should >> work and add it to motion's homing state machine. I don't think you >> can easily patch it up outside of motion. >> > I understand that gentrivkins and ja3 works acceptably, but I have no > idea if this also includes index-homing. It seems to me that it can > only really work if the two indexes are set up in the right place. > (or, I suppose, if the encoder components grew a fixed-offset pin) > >
I think index homing on a gantry would only be worthwhile if home offsets could be applied after the index/marker pulse was found. On a big servo system, you aren't going to want to rotate the motors to get the index/marker pulses aligned so the gantry is square. It just isn't practical. Dave Cole ------------------------------------------------------------------------------ Try New Relic Now & We'll Send You this Cool Shirt New Relic is the only SaaS-based application performance monitoring service that delivers powerful full stack analytics. Optimize and monitor your browser, app, & servers with just a few lines of code. Try New Relic and get this awesome Nerd Life shirt! http://p.sf.net/sfu/newrelic_d2d_may _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
