Encoder index search finds multiple index positions

#1

The encoder index search process doesn’t find the same index location each time. Each time I initiate an index search the motor will spin for a couple degrees and then claim that it found the encoder index regardless of its absolute position.

I assumed there was something wrong with the wiring, but I’ve been able to verify that the index line is working properly with an oscilloscope (5V spike at the index, 0V everywhere else). Has anyone else had this problem/know any possible causes for this behavior?

Thanks

#2

Hello nikolaif399, I had noise issues with index pulse. Index pin looks OK with an oscilloscope without motor turning, but once it starts moving there was lot of noise. Did you check the signal while motor is doing the index search? Anyways, this post is a different encoder noise issue but was mitigated with a capacitor.

#3

Hi naktamello,

Thanks for the suggestion, noise was my first instinct as well. I’ve tried observing the index line during index search (motor running) and a 1.5V trigger does not trip despite the index search returning that it found the index. I can try adding a small cap to the line, but I’m still confused why the search thinks it’s found the index if the voltage doesn’t trip the scope trigger.

#4

This is another post that I remember was about encoder index issue, although this user’s index signal was abnormal on oscilloscope to begin with, in case this leads you to any clues. I hope you find an answer soon.

#5

I recently stopped getting the index’s pulse on one of my drives. I haven’t figured it out yet…

Before this I had a lot of issues getting a good index and ended up having to ground my encoders directly back to the ground of the power input.

#6

Hi Anthony,

Did attaching the encoder ground to power ground solve the issue?

#7

It solved my original issue of false index finds…I haven’t yet solved why I’m not getting the pulse altogether now.