On Monday 16 July 2012 23:34:22 Jon Elson did opine: > Gene Heskett wrote: > > On Sunday 15 July 2012 23:29:40 Jon Elson did opine: > >> Now, I'm not too clear on the +/- 3 fluctuation in terms of > >> REVOLUTIONS rather > >> than COUNTS, which you seem to be saying above. > > > > That is exactly what I am saying Jon, using the hal encoder module. > > > >> I completely expect > >> jumps of +/- 2 counts/sample, but that should be divided by the > >> number of encoder counts/rev. If the measured speed is jumping by > >> +/- 3 RPS, > > > > It is. > > > >> something seems to be really wrong. > > Well, something IS really wrong. Detective work is needed. Have you > run the > latency tests, with something like glxgears running, to simulate the > axis 3-D > preview load on the graphics system?
Yes, overnight even, latency is very very good, 2.3 u-secs. > I gather now you are using the hal encoder component. You need to be > sure that the > update-counters function is called from the base thread, and that the > hal_parport > is also called from the base thread. If these are being called from the > servo thread, > it will introduce higher latency and cause it to miss counts. > > What is the base thread set to? 23,000 > What is the encoder resolution 39 slots, 156 edges in quadrature mode. > and the > top speed you intend to achieve? You have mentioned 20 RPS = 1200 RPM. The spindle has a gear shift and in high gear can make 2500 revs. Thats a hair over 40 rps, and the encoder doesn't appear to be suffering from skipped counts. > For it to work, you need to be sure that the base thread is running > fast enough that it samples more than once per count from the encoder. > So, for 20 RPS x 400 counts/rev (100 tooth encoder wheel) that is 8000 > counts/second. Your base thread should be twice that rate, so 16000 > samples/second, or BASE_PERIOD=62500 Way faster than that, 23000, and the wheel has only 39 slots. > > I have not been able to see/find a signal with > > > > halscope that zeros itself on the index pulse. > > This only occurs when an axis is synched to the spindle, at the > beginning of a threading operation such as G33 or G33.1 > > OK, so you've checked the sensors themselves, but maybe there is > something interfering wit the computer reading the sensor signal. > Since you are using the hal encoder component, the A and B quadrature > signals are available to Halscope. Maybe there will be some > disturbance there. None visible. If I run the speed open loop, the worst I can see if the reset falling edge is jittering at nominally 1 count of the base thread, one pixel's worth of jitter in the halscope. > It really HAS to be on these signals, the encoder > component works as designed, and hasn't needed any adjustments in the > counting section since 2009. I was going to copy my .hal file over and post it, but for some unk reason I suspect I'll have to reboot this box to restore NFS to usable. I did have it working a couple days after the last reboot, but the /net directories on all 3 machines are now empty except for the lathe box, it can see its name as /net/lathe, but /net/lathe is empty on lathe.coyote.den. Is there a way to setup nfs that Just Works(TM)? This is all a private network, using host files. I _think_ all the usual suspects have been properly configured. Thanks Jon. Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) My web page: <http://coyoteden.dyndns-free.com:85/gene> is up! Etiquette is for those with no breeding; fashion for those with no taste. ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
