> Do you have a dual trace 'scope? Spin the spindle and look at the input > and output of the opto-isolator. See if there really is a lag. If you > have a new scope would you have it capture the screen and post it. I'm > really skeptical that those isolators are THAT bad. > > Here is the datasheet for the opto. > https://www.mouser.com/datasheet/2/143/EL817-G-26528.pdf > They claim an 18 uS rise and fall time. A 1KHz square wave will have a > 1000 uS period and a 500 uS pulse width at 2 KHz the pulse width is still > more than 10X the raise time of the opto. But maybe the opto is a fake > counterfeit part with very poor performance.
Opto couplers are rather slow. With a high resolution encoder frequency could be maybe up to a few hundred kHz, 2000*period/revolution*3600rpm=120000period/second=120kHz, 200PPR will be 12kHz at 3600rpm, 1/(2*18µs) = about 27778Hz = about a little bit below 28kHz if mad no misstake. _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
