I've seen this too. non-constant RPM when you know the rotating mass has enough inertia that the RPM can change so fast.
What I found is that the resolution of measuring the encoder is low and what I see is quantization noise. This means I'm not sampling with enough bits. You are sampling to fast and getting killed by the statistics of small numbers. There are two ways to read and encoder: 1) each "tick" samples a fast running clock and you measure the period and 2) each tick increments a counter and periodically sample the count. If you use the wrong method you get the variable RPM problem You want to get at least 100 counts per sample using whatever method. On Sat, Oct 27, 2018 at 6:47 PM Alan Condit <condit.a...@gmail.com> wrote: > I have a homemade encoder on my lathe spindle. I am feeding the encoder > outputs into the encoder spindle inputs on the 7I76. The reported rpm seems > to be fluctuating wildly. I want to look at the signals to see if the width > of the signals is about the same for the index on time and for channel A > and B on and off times. Is it possible to look at the encoder signals with > hal scope? Or do I need to drag my oscilloscope out to the shop. I don’t > see the pins in the hal file. > > Am I even thinking about this correctly? > > Alan > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > -- Chris Albertson Redondo Beach, California _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
