Re: EMC and stepper driver

Mariss Freimanis:

After reading your post on the G210 i checked your web site for more
information read the manual, looked at your technical section read
the messages in your forum and searched here for old messages. Not
very much real world info out there. But also found out drive was
only released this month.

Do you have any real world performance stories on this drive. Like
how much faster it runs on EMC compared to other drives. Or speed
and torque curves showing improvment with this drive.

Also i looked back on the messages you left on updating the G201 and
noticed the G210 was not included. Personaly i would want the G210
to have the mods you talked about. The automatic current foldback
and the higher drive voltage. As I would like to drive M112 motors i
think these are size 42.

Wally K.

--- In CAD_CAM_EDM_DRO@egroups.com, "Mariss Freimanis"
<geckohall@h...> wrote:

> > Wally replys:
> >
> > I do not think the stepper drivers could have this feature. If

you

> > are running 2 or 3 axis and each drive is buffering the step
> signals
> > you would probally loose sync of the stepper signals in relation

to

> > each axis. This would be a disaster in circular interpolation.
> >
> > Wally K.
>
> Hi,
>
> Let me clarify two points:
>
> 1) The pulse multiplier does not buffer steps in the conventional
> sense. What it does is output 10 evenly spaced microsteps for every
> full step input. It anticipates what the next full step period will
> be based on previous periods in order to evenly space the

microsteps

> for every new full step input. This has the benefit of making the
> motor more tolerant of poorly spaced (ragged) full steps at high
> speed. Because there are 10 microsteps for every input step, the
> resolution is the same as a full step drive except the motor moves
> with microstep smoothness at low speeds.
>
>
>
> 2) The servodrive has a +/- 128 step "buffer"(This buffer could
> overflow/underflow except for the FAULT detector. It shuts the

drive

> off when the error reaches +/- 120 counts).
>
> Every step sent to the drive adds to the buffer; every step taken

by

> the motor subtracts from it. When both match (step issued, step
> taken), the contents are zero regardless of speed.
>
> The contents of this buffer is "0" steady-state because the PID
> compensation does not permit a steady-state error. As long as what

is

> asked of the motor is within its ability (accel/decel), the

contents

> of the buffer stays zero. The only time it is other than zero is

for

> transient events.
>
> One example is asking the motor to instantly change speed, say from
> 500 RPM to 1,000 RPM. The buffer initially goes negative (falls
> behind) because it would take infinite torque to instantly change
> speed. A negative-going buffer pours coals to the motor and it
> accelerates to make up the difference between where it is and where
> it ought to be.
>
> As it catches up with the moving target, the buffer goes to zero,
> acceleration ceases and the motor's speed and position match the
> target.
>
> Mariss