On Thursday 03 September 2015 05:09:53 andy pugh wrote: > On 3 September 2015 at 05:34, john mcintyre <[email protected]> wrote: > > The Mazak M3 lathe bed has six equally spaced limit switches, > > which are individually connected to a six pole rotary switch this > > allows, only one limit switch to be active. > > That should work fine with LinuxCNC as-is, but I don't think that > there is an easy way to change the homing direction on-the-fly. > Ideally each switch would define a different HOME_OFFSET so that each > switch homed to the same absolute home, and I don't think that is > trivial either. > > It _might_ be possible to make a HAL component that sends an NML > message to change the home offset when the switch is moved: > http://linuxcnc.org/docs/html/code/NML_Messages.html#_emc_axis_set_hom >e_offset_type
That maybe could be made to work, but with 6 positions to tally, the switch would need a 3 bit wide output in order to indicate which position it is in. That, for a 5i25 user, we would need to convert 3 unused gpio's to inputs so that would be easy to do in the hal file. However, there are not to my knowldge any breakout boards capable of having an output bit converted to an input bit unless we design one to be easily switched. Is there such a beast and I just haven't spotted it? A bit of googling seems to say that cnc4pc has a no active devices board, no buffers at all, for $9.12 Thats a bit scary around the electrical noise of a cnc machine. I didn't find anythng obvious at mesanet. The pmdx-122-d could be used on a 5i25's p2 connection (adding another cable to the cable count though) and set to make the 8 data bits inputs, so that is one possible solution. Maybe the only one that gives us that versatility. For my toy, just another switch at the right end of of the bed would suffice. But unless a method can be found to switch all the home seeking directions too, we would have to first move it beyond the switch before invoking the homeing command. Failing to do that would be an ex$pen$ive tool wrecker by running it into the fixed steady. I'm up too early, need nap or coffee. A nap sounds good. I did stumble over a bag of LM317's last night though, so I now have an isolated alu slab of 1/8" alu rigged as an insulated heat sink I can put where one of the fans will cool it. So I might have the lathe fully functional by the end of the day again. Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ Monitor Your Dynamic Infrastructure at Any Scale With Datadog! Get real-time metrics from all of your servers, apps and tools in one place. SourceForge users - Click here to start your Free Trial of Datadog now! http://pubads.g.doubleclick.net/gampad/clk?id=241902991&iu=/4140 _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
