Re: EMC problem/question

Jon:

I got a chance to try "freqmod" as you suggest. After some futzing I
was able to get good motion from both X & Y. The P parameter was the
original problem. I went down to 100 and then started back up getting
to around 500 with good motion. I did set a dwell of .0005" which
stopped the dithering. I think I'm getting faster motion from freqmod
than steppermod but as yet have no numbers. I didn't put the
opto-isolation back in to see if it works with freqmod though.

I need to find the time to optimize the setting and see which works
best. But great progress is being made here. Thank you for your help.

On 6 Aug, Jon Elson wrote:

>>
>> I just tried this on a 450MHz PIII.
>
> Oh, of course! Freqmod.o simulates a servo, as I mentioned in a previous
> comment. Well, that means all the PID servo calculations are performed,
> and loop stability is an issue. If the P (proportional gain) is too high,
> unstable
> performance will be seen. that is what I think is happening there. Turn P
> down to around 100 and try some motion. If that works OK, turn it up
> in small increments (you'll get a bit snappier performance) until either
> the steppers lose steps or the motors start to sound rough, then go back
> down some safe interval. You may have to set a larger following error
> limit as lower P causes more lag.

--
Hugh Currin
Klamath Falls, OR