Do you see any relationship between the amount of O-counts and the speed at which you run the motor. IDo you get less O-count if you run the motor at 100rpm for a minute compared to if you run it at 1000rpm?
It could be a problem with PCB layout so switching noice from the powerstage upsets the controller. I've only used the HP-UHU so I have no experience with the other versions available but I've read numerous times that some are very sensitive to noice.
If you have a scope, look at the signals and verify the phase shift and signal levels etc. Try feeding the encoder with a separate +5V supply (common ground with the drive of course) and then run the motor very slow. Still getting O-counts?
/Henrik.
PS. I had HUGE problems with invalid counts and lost postion on my system and I worked on it for several weeks trying to figure out what was wrong. I had brand new USDigital E7P encoders with linedrivers and I tried just about every trick in the book (and some not in the book) regarding grounding, shielding, powersupply filtering, separate powersupply for the encoder, cable length, cable type, filtering - you name it. It simply refused to work. In the end I was convinced it was the encoders that was the cause. I threw the brand new USDigital encoder in the spare parts bin and got some RENCO encoders and the problem went away for good.  |