Re: EMC and stepper driver

Tim:

Thank you for the insitefull reply. You did a very good job of
explaining why the servo has less problems with a pulse train then a
stepper.

I have one other question for you. You talked about 30,000 steps per
second from emc to your servo system. Do you know what the upper
limit is for steps per second that EMC will output.

Wally K.

--- In CAD_CAM_EDM_DRO@egroups.com, Tim Goldstein <timg@k...> wrote:
> The servo is not looking at the step signals in the same manner the
stepper
> is. On the stepper if the pulse train gets unevenly spaced you are
very
> rapidly accelerating and decelerating the stepper and it will
stall. On the
> servo you are just loading an accumulator that is driving one side
of a
> comparator. The other side is loaded by the encoder. If there is a
> difference an error signal is generated that drives the servo
motor. The
> accumulator does not care about the evenness of the pulse as
acceleration is
> handled by the degree of the error signal, not the rat of the
steps. Also, a
> servo motor does not have the same sensitivity to acceleration as a
stepper.
>
> Tim
> [Denver, CO]
>
> > I have stolen the following post from a emc message site.
> >
> > http://www.nist.gov/itl/div896/emaildir/emc/msg01620.html
> >
> > It is from our very own Tim Goldstein, and deals with Steppers
and
> > servos under EMC. acording to Tim the G320 servo drive runs
great at
> > 30,000 steps per second and steppers with a stepper drive cant
run
> > any way near this fast.
> >
> > My question is. Is the front end of the G320 somehow
conditioning
> > the signal or are servos just more forgiving. If the G320 is
> > conditioning the signal then we should ask Mariss at geckodrive
to
> > put this conditioning in his line of stepper controllers.
> >
> > Wally K.
> >
> > FAQ: http://www.ktmarketing.com/faq.html