Andy, Since Dewey released the homemod functionality that allows you to build custom homing routines, I've been working with Dan Dempsey on developing a custom homing component for cia402 compliant drive. Dominc Braun released a component that can home cia402 (eg an Ethercat canopen standard) drives. See: https://github.com/dbraun1981/hal-cia402 I have played enough with this component enough to know it has homing shortcomings where absolute encoders are not used. The CIA402 standard allows connecting external home and limit switches and a plethora of homing methods that define direction of travel and latching, many of which reflect the Linuxcnc homing configuration documents. Some drives support home by stalling without using any home or limit switches. So to implement these features, all you do is tell the drive to home and wait until it tells you it is homed. As you can imagine Linuxcnc is not very happy with motion it has not commanded so this is a recipe for instant following errors that need to be handled.
The approach I have taken is to expand homing read_homing_in_pins() and write_homing_out_pins() functions to incorporate Dominic's read_all() and write_all() functions. It's been pretty slow going as in a homemod, you need to manage all joints whereas using Dominc's component, this is managed as a separate instance of the component for each joint. I have got as far as seeing some motion when jogging before homing but its rough so I have not got it right yet. I am also not resetting the status words correctly when turning linuxcnc off from the axis orange button. When I get that working, I will be able to code a much simplified state machine in do_homing(). The one unknown is how the execution order in the servo thread loop in relation to a homemod and the lcec ethercat driver. We may end up being 1 servo cycle behind.. In answer to Gene's question re advantages, wiring can be much reduced and homing should be more accurate because the drive should respond to a change in homing state between servo thread invocations and wait patiently for Linuxcnc to see the homed state when it next looks. Now if only I could get etherlabmaster installed on a Raspberry Pi running the later Bullseye or Bookworm kernel. But that's another story... Rod Webster *1300 896 832* +61 435 765 611 Vehicle Modifications Network www.vehiclemods.net.au On Wed, 4 May 2022 at 01:30, gene heskett <ghesk...@shentel.net> wrote: > On Tuesday, 3 May 2022 10:11:46 EDT andy pugh wrote: > > On Tue, 3 May 2022 at 14:24, gene heskett <ghesk...@shentel.net> wrote: > > > Homing can be a complex subject, what we have in master seems to > > > work, if you play by its rules. Does this change them? > > > > Only if you want it to. > > Advantages? > > 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, 1940) > If we desire respect for the law, we must first make the law respectable. > - Louis D. Brandeis > > > > > > _______________________________________________ > Emc-developers mailing list > Emc-developers@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-developers > _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
