So the spindle spins about up to about 3,000 RPM. That is 50 rev. per second. You have a 1,000 line encoder so that is 50,000 lines per second on each channel. You should seeing a 50 KHz square wave on both A and B channels. I don't understand the 1.8 MHz reference.
On Wed, Nov 29, 2017 at 4:38 PM, Gene Heskett <[email protected]> wrote: > Greetings all; > > Does anyone have a 256 line/rev encoder that would like a 1000 line > version? > > Sitting on the rear of the motor, with the encoder filter in a 5i25 > turned off, I can get to around 1750 spindle rpms before the 5i25 > encoder falls over and the tach drops to zero. > > Looking at the signals, it may yet be in the SainSmart BOB as the encoder > has a differential output, and I'm only useing 1 of the leads. When > enabled, the motor settles at about 3x what the encoder can track, and > looking at the bob with a scope, I see its something north of 1.8 MHz > with an rc slew rate limited waveform, which the bob cleans up to a > square wave but nowhere near a 50% duty cycle, 15% high time maybe. > > I have some comparators of the *86 variety that I can make differential > receivers out of, which should even up the duty cycle to around 50%. But > I'm not sure that will be enough since the motor, in high gear, can do > 2950 at the spindle until a thermal in the windings stops it for about a > minute. So I normally don't run it above 2750. > > So I'll make the differential to single ended gizmo to see if it might be > enough. If thats not enough, maybe somebody wants a higher resolution > encoder they can direct couple to their spindle? > > I just noted the encoder_sample is set for 500000 in the ini file. Would > turning that up help, or is that the limit? > > Thanks all. > > 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> > > ------------------------------------------------------------ > ------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > -- Chris Albertson Redondo Beach, California ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
