On 24 May 2013 04:36, Jon Elson <el...@pico-systems.com> wrote: > These rigid gantrys seem like you could get into trouble, and the homing > needs to be done the right way or it could throw the machine out of > square.
As I understand it, the one thing that gantrykins is good for is homing. As far as I know it Just Works. Both joints move at the same speed to their home switches, and then run through the latch sequence. If the gantry is perfectly square at the start, it will stay perfectly square throughout. If it is slightly out-of-square then it will only ever get ore square through the homing sequence. For peace-of-mind I would suggest an e-stop trigger on encoder position divergence. This needs to be masked by the homing state, as there is a sudden step in position at the homing point. I think I would put this mask in a HAL comp, and add in a timer that also throws an e-stop if there is more than a certain time difference between each side switching state: This was all looking very easy until I noticed that axis.N.home-state is a parameter (the only axis.N parameter in motion...) http://www.linuxcnc.org/docs/html/config/emc2hal.html#_parameters_2 if it _wasn't_ a parameter, and was instead a pin,then the comp body would jut need to be: ;; if (home_state(0) == home_state(1)){ timer = 0; if (fabs(position(0) - position(1)) > tolerance){ e_stop_out = 1; } else { timer += fperiod; if (timer > maxtime){ e_stop_out = 1; } } I have no idea how you escape from this e-stop condition, however. It may need an "enable" pin linked to an over-ride keyswitch. (though it will clear on a complete power-down when the encoders both zero) -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto ------------------------------------------------------------------------------ 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-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
