On Sunday 08 September 2019 15:10:54 Peter C. Wallace wrote: > On Sun, 8 Sep 2019, Gene Heskett wrote: > > Date: Sun, 8 Sep 2019 11:44:23 -0400 > > From: Gene Heskett <[email protected]> > > Reply-To: "Enhanced Machine Controller (EMC)" > > <[email protected]> > > To: [email protected] > > Subject: Re: [Emc-users] Step timing and max velocity > > > > On Sunday 08 September 2019 06:55:58 Peter C. Wallace wrote: > > > > On Sun, 8 Sep 2019, andy pugh wrote: > > > Date: Sun, 8 Sep 2019 10:50:54 +0100 > > > From: andy pugh <[email protected]> > > > Reply-To: "Enhanced Machine Controller (EMC)" > > > <[email protected]> > > > To: "Enhanced Machine Controller (EMC)" > > > <[email protected]> Subject: Re: [Emc-users] Step > > > timing and max velocity > > > > > > On Sun, 8 Sep 2019 at 04:41, andrew beck > > > <[email protected]> wrote: > > > > > >I can move the table at max speed but the Stepgen PID errors out. > > > > > > > > >Can you elaborate on this? > > >PID has no error messages, as far as I know. So what is the actual > > > error? > > > > > >What is PID.n.maxerror set to? > > > > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > > > > I almost guarantee this is the issue, Some earlier versions of > > pncconf set this to .0005 as a way to make the stepgen more robust > > with regard to host servo thread jitter but the number only makes > > sense in inches so fails on metric machines. This should be set so > > say .0127 on metric machines (or just 0) to disable the correction > > limit completely. > > > > Other values: > > FF1 = 1.0 > > P= 1/servo period (so normally 1000) > > and if you are very fussy: > > FF2 = seconds from position read to velocity write > > about 0.0001 on Ethernet cards > > And that is the first time I've seen a spec for FF2 that makes any > sense, thank you Peter. What would be roughly correct for a 5i25-7i76 > combo? > > Probably around 20 - 50 usec so .00002 to .00005 > > But it will not make a noticeble difference unless you need pulse > fidelity in the <100 uinch range at 1G acceleration hence the "if you > are very fussy" disclaimer
I doubt its super important then as most of my acells are in the 4 to 15 range, which I assume would overpower the fine tuning. Thanks Peter. > > >Is your FF1 correct? In a cruise, using > > >halscope, you should see the > > >velocity command and the actual velocity pretty much equal. > > > > > >-- > > >atp > > >"A motorcycle is a bicycle with a pandemonium attachment and is > > > designed for the especial use of mechanical geniuses, daredevils > > > and lunatics." ÿÿÿÿ George Fitch, Atlanta Constitution Newspaper, > > > 1916 > > > > > >_______________________________________________ > > >Emc-users mailing list > > >[email protected] > > >https://lists.sourceforge.net/lists/listinfo/emc-users > > > > Peter Wallace > > Mesa Electronics > > Cheers, Gene Heskett 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) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
