Our 80's vintage matsuura started losing counts when the 5v supply started to lower.. don't remember how far down.. Maybe 4.7v?
On Sun, Oct 2, 2022, 11:54 PM gene heskett <ghesk...@shentel.net> wrote: > On 10/2/22 22:25, John Figie wrote: > > So if you missed an A or a B pulse from the encoder I think you should > see > > the position count go in the opposite direction for one count. Another > > words, instead of a position sequence of 0,1,2,3,4,5,6,7 you might see > > instead 0,1,2,3,2,3, and in addition the time spent in 3 followed by 2 > > would each be twice as long. So maybe if you can trigger on a non > > monotonic position sequence you can capture the event. > > > > John Figie > > > > On Sun, Oct 2, 2022, 7:49 PM Jon Elson <el...@pico-systems.com> wrote: > > > >> On 10/2/22 19:34, John Dammeyer wrote: > >>> Oh boy does that bring back memories. > >>> I started with the US Digital Encoders on the DC Servos. According to > >> the designer of the PIC upgrade board for the HP_UHU Servo drive the US > >> Digital were crap and caused nothing but problems. > >>> I switched to CUI and it appeared to be better. Until one day circle > >> milled inside a piece was off center. See photo. > >>> That’s when I started doing what you did and discovered that at very > >> slow speeds I could return to the same 0 position but faster moves lost > >> steps. The error happened in only one direction. > >>> Eventually I discovered that if I swapped the motor+encoder with the Y > >> axis the problem moved to the Y so it wasn’t the HP_UHU drive. Further > >> research showed the X axis motor winding resistance was almost double > that > >> of the working Y axis motor. > >>> It's possible I might have been able to fix the problem by doubling the > >> current setting on the motor. They were bought at the same time and > were > >> supposed to be identical. > >>> I don't know why the HP_UHU servo drive didn't catch the position loss. > >> Like yours, the encoder signals looked nice. The CUI encoders seem > to be > >> high > >>> One other point. I switched to the Bergerda AC Servo drives which to > >> date have been great. Talking to Donald Chen the sales guy at Bergerda > he > >> mentioned that their encoders are Japanese and more expensive than ones > >> used on a lot of their competitors. After that conversation I took one > >> apart and checked part numbers. Sure enough, Japanese design made in > China. > >>> So try different encoders. > >> Yes, I did see some really strange signals on the scope > >> before. I tore the whole motor/encoder set apart and cleaned > >> the inside of the encoder. But, optical components in the > >> encoder are held in place with glue, 39 year old glue! I'm > >> having doubts that everything is still properly aligned in > >> there. > >> > >> So, I'm leaning toward replacing the encoders with newer > >> high-end encoders with higher line count. But, that will > >> require machining adapter plates and making sure the > >> encoders are well-centered. > >> > >> Thanks, > >> > >> Jon > Jon and John, I'd vote for a lack of good "star' grounding. Somehow the > encoder is picking up noise from the > motors reversal. So you are getting an extra noise pulse into the > encoder wireng and its going to be direction > switch related. A good star ground, and all that just goes away. Even > with unshielded cables. > > The whole point of the star ground is that this common ground may not be > quiet. But everything is > referencing the same bolt. that bolt may not be grounded to earth, and > can be bouncing around 500 volts, but its > carrying ALL the logic with it and the logic is only sensitive to the > logic level between the wire from the encoder > and that star bolt. As far as individual line cords are concerned, only > one third pin should actually get to the wall, > More than one third pin is a ground loop and a noise src. > >> . > >> > >> > >> _______________________________________________ > >> Emc-users mailing list > >> Emc-users@lists.sourceforge.net > >> https://lists.sourceforge.net/lists/listinfo/emc-users > >> > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > 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, 1940) > If we desire respect for the law, we must first make the law respectable. > - Louis D. Brandeis > Genes Web page <http://geneslinuxbox.net:6309/> > > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
