The effective pulse width is always zero if you look at the leading edge. Pulse length does not matter.
If you care about being the same in each direction then look at the leading edge when going in the normal direction and if running in reverse look at the trailing edge of the index pulse. The quadrature sensor will tell you the direction. Look at the last data from the A/B channel to determine direction then decide what index edge to use. The worst case is when a person turns the spindle by hand with the motor powered off and moves the spindle back and forth many times triggering the index from both directions. The above should track this well. But in real life, you never see this worst case. But still, it can be handled with just a few lines of code. On Thu, Nov 29, 2018 at 11:13 AM Peter C. Wallace <p...@mesanet.com> wrote: > On Thu, 29 Nov 2018, David Berndt wrote: > > > Date: Thu, 29 Nov 2018 12:13:25 -0500 > > From: David Berndt <ber...@uberwin.com> > > Reply-To: "Enhanced Machine Controller (EMC)" > > <emc-users@lists.sourceforge.net> > > To: emc-users@lists.sourceforge.net, Peter Blodow <p.blo...@dreki.de> > > Subject: Re: [Emc-users] Spindle Encoder AEDR-8300 Encoder Ring > > > > Ok, thanks guys. I'll go with a seperate encoder to pickup a once per > > rotation count. Are there any requirements about on/off span in relation > to > > A/B. The "centering" of the index pulse sounds like it could be a bit > > fiddly, and getting the pulse perfect would probably be difficult as > well, > > presumably linuxcnc won't be comparing A/B to index for any reason, just > > needs that index pulse (+A/B count scaled at 1RPS). > > Mesa encoder hardware has the option of gateing index with the quadrature > state but thsi is currently unused > > The only disadvantage I see from a wider index pulse is that the index > location would differ in different spindle directions. I dont think there > is > any circumstance in normal LinuxCNC machining operations where this makes > any > difference at all. > > Peter Wallace > Mesa Electronics > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > -- Chris Albertson Redondo Beach, California _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
