On Tuesday 06 October 2015 19:56:00 Peter C. Wallace wrote: > On Tue, 6 Oct 2015, Gene Heskett wrote: > > Date: Tue, 6 Oct 2015 16:44:41 -0400 > > From: Gene Heskett <ghesk...@wdtv.com> > > Reply-To: "Enhanced Machine Controller (EMC)" > > <emc-users@lists.sourceforge.net> > > To: emc-users@lists.sourceforge.net > > Subject: [Emc-users] joint following errors by the kiloton > > > > Greetings all; > > > > I gave up on that crashomatic box, and went out and found me one of > > those Dell 745's with an Intel dual core running at 2.6GHz, and > > 4Gigs of DDR-2. But I couldn't move that drive, no PATA connectors > > on the mainboard. So I had to install fresh, which went rather > > swimmingly, taking perhaps a half hour after I'd put my only new > > SATA drive in it, a 2 Terrabyte Seagate I had more or less reserved > > for amanda's useage. > > > > I of course installed some of my personal pets, like mc, sshfs, > > unclutter and synaptic. > > > > I let the package manager update aroun 350 packages including > > switching our repo to master-rt, and about mid-morning there was > > another update to the 2.8.0pre, which I automatically installed. > > > > But at that point I was still hacking up low profile brackets for > > the 5i25 and its p2 breakout. > > > > Getting that going, I was amazed that there was not a > > /home/gene/linuxcnc directory made by the installer! Is that a bug, > > or is that a function of running pncconf the first time? > > > > I got sshfs working, and copied the 5i25.zip over to the new box, > > unpacked that and installed the 2 files my 5i25 card needed. > > > > And installed boot.ko, needed to start Jon's pwm servo amp. > > > > And convinced amanda I needed to recover my /home/gene/linuxcnc tree > > so I had all my configs and gcode back. > > > > And I've been the last 4 hours trying to get the machine to > > succesfully home. I don't care how slow you set the speeds in the > > trajectory or axis# sections, it will throw a joint following error, > > either while cruising along at 10 IPM (last week it could move 70 > > IPM except for Z & it could do 45!) or in making the stop when a > > home switch has been hit. Its also moving some faster than any > > setting in the .ini file. > > > > Somewhere along the line it WILL throw a joint following error. On > > axis X, or axis Z. > > > > Latency test has been run, and the servo-thread jitter is about 40 > > microseconds. isolcpus=1 is in effect and working. > > > > Can this be an sms problem? Or is this something all aglay in the > > 2.8 development branch? > > > > What is the best way to switch it back to the current 2.7.0 & see if > > that fixes this? > > > > Thanks. > > > > 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> > > > > -------------------------------------------------------------------- > >---------- _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > Hardware stepgen following errors usually come from the servo thread > jitter > > If the built in position mode stepgen driver is used, its quite > intolerant of servo thread jitter and goes bonkers if you have > significant servo thread jitter and you dont bound its acceleration. > The normal fix for this is setting the stepgens max_accel parameter to > about 20% greater than the machines max_accel setting. > > This works acceptably in most cases but if you need better servo > thread jitter tolerance, using the hardware stepgens in velocity mode > and using a PID loop for position feedback (from the stepgens feedback > counter) works much better > > In this case you set the PID parameters thusly: > > P = 1/servo period ( that is P= 1000 at 1 mS servo thread ) > > FF1 = 1.000 > > FF2 = number of seconds between HM2 read and write (probably about > .00005 or 50 usec on a PCI system) > I may have blown that, I won't swear on the usual book that I had 4 zeros in there. May have been 3. > > MAX_ERROR = ~.0005 > > In addition to PID, in drastic cases, a config that incorporates the > DPLL component can deal with latencies up to a few hundred usec. > The above settings seem to have brought it under control, but one question, 2 actually, remain.
1. MAX_OUTPUT was set for 32.5 by PNCconf, but looking at it with a halmeter it appeared to be setting a restriction on how much "catchup" was available, so I had raised that to 50 some months ago, and tonight I raised it to 100, which seemed to alleviate the Z coasting far enough after it had hit the home switch, to hit the top of the slot in the post with the nut holder brackets leg about 2mm above the switch. With MAX_OUTOUT at 100, and some pretty aggressive accels that I may raise some more, it stops a few thou short of banging the top of the slot in the post. I came back in with it working, but the FERROR at 0.0001 is a nothing add, because MIN_FERROR is still 1.0. And it was tripping off at that 1.0 & very small change. Was this correct for a millimeter machine? Thanks Peter, I can go back to checking why some hal code isn't running a transistor which is supposed to be running a bigger relay, turning a vacuum cleaner on and off so it sucks up the sawdust I about to make a few bushels of. I made a centrifical separator out of PVC stuff so as to dump the majority of the sawdust into a 5 gallon bucket on its way to a shop-vac "Bucket Max". I've cleaned up the floor a couple times awith it and it seems to be doing a decent job of separating the sawdust into dust & semi-clean air. Makes a $30 HEPA filter last a lot longer. Thats tied to the flood checkbox, while the mist button is tied to a motor via a DPDT relay to flip the jigs locator bar and touch points in and out of the way. So tomorrow I go pay the guy for his computer. It is going to do the job I believe. When he found out who I was, and what I wanted to do with it, he refused to take my money before I found out if it would work. Now I know it will. ;-) I like doing business with folks who actually know something. Thanks Peter. > > Peter Wallace > Mesa Electronics > 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> ------------------------------------------------------------------------------ Full-scale, agent-less Infrastructure Monitoring from a single dashboard Integrate with 40+ ManageEngine ITSM Solutions for complete visibility Physical-Virtual-Cloud Infrastructure monitoring from one console Real user monitoring with APM Insights and performance trend reports Learn More http://pubads.g.doubleclick.net/gampad/clk?id=247754911&iu=/4140 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
