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 <[email protected]> > > Reply-To: "Enhanced Machine Controller (EMC)" > > <[email protected]> > > To: [email protected] > > 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 > > [email protected] > > 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 )
No direct feed via FF0? > FF1 = 1.000 > > FF2 = number of seconds between HM2 read and write (probably about > .00005 or 50 usec on a PCI system) > > > 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. > > > Peter Wallace > Mesa Electronics > These were originally set by PNCConf, and I have not touched the p.i.d values that were assigned. Latency jitter on the servo-thread is less than 50000 ns, or 50 microseconds. The box I took away was an amd, and ran in the 30000ns range, with virtually zero problems as long as the box hadn't stopped or crashed. Which was x times daily. I was just watching the axis f-error with a halmeter, and it seems to be a time * speed that builds up as it moves until it finally trips, and if I run it a few inches and stop, the .5xxxxx reading at the stop point, bleeds off like a leaky capacitor, reaching its minimum value in about 10 to 15 seconds. I don't recall ever seeing it behave like that before X & Y P's are set to 50, Z's P is 75, and all I's and D's are set to 0.0, as were FFO and FF2. I'll go set it up as you recommend & report back. Thanks Peter. 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 [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
