Gecho 210 step multiplier, was Re: [CAD_CAM_EDM_DRO] Stepper Math

Hi,

The pulse multiplier (G901) is a phase-locked loop circuit. Its
output goes to a G201 10 microstep drive. Its purpose is to appear
like a full-step or half-step drive to the user while it moves the
motor with microstep smoothness.

In full-step mode, all motor movements are in 10 microstep
increments. If you send it 200 step pulses, it will output 10 times
200 or 2,000 pulses to the 10 microstep drive it sits in. The motor
will take 1 revolution, just like a full-step drive, except the motor
will turn without vibration or resonance.

Here's how it works in full-step mode:

The steps you send it increment a 4-bit up/down counter. The
counter's outputs go to a 4-bit D to A converter. The D to A output
goes thru a PID compensation amplifier. Its output goes to a VCO
(voltage controlled oscillator). The oscillator output goes to the
G201 step input and to a divide by 10 counter. The counter's output
decrements the 4-bit up/down counter, which closes the loop.

In operation, the VCO frequency divided by 10 exactly tracks the
input step pulse rate. This means the VCO frequency is exactly 10
times higher than the input step frequency. It tracks the input
whether it is accelerating, decellerating or running at a constant
speed. The microstep smoothness is set by the PID loop co-efficients.
These values are based on optimum loop transient (lag-lead) response.

Mariss

--- In CAD_CAM_EDM_DRO@y..., "Guy Sirois" <guys@w...> wrote:
>
>
> Paul,
>
> I was talking about the Gecko G201, not the G210.
>
> Your comments are true regarding the G210.
> It is used to smooth out or speed-up a drive's output.
>
> I would like Mariss to comment/explain how the 210 responds to a
pulse train
> that is accelerating or slowing down in frequency. It seems to me
that the
> pulse spacing can not be very regular until the frequency has
stabilized.
>
> Regards,
> Guy
>
>
> -----Original Message-----
> From: Paul R. Hvidston [mailto:paul_hvidston@y...]
> Sent: Monday, February 25, 2002 12:34 PM
> To: CAD_CAM_EDM_DRO@y...
> Subject: Gecho 210 step multiplier, was Re: [CAD_CAM_EDM_DRO]
Stepper
> Math
>
>
> Guy,
>
> I think there's some confusion about the Gecho210's step
multiplier. The
> manual says:
>
> "The G210 has a built in STEP PULSE MULTIPLIER. This circuit puts
out 1, 2,
> 5 or 10 pulses for every input STEP pulse."
>
> This is the opposite from microstepping. It seems like the only use
for a
> step multiplier is if your system cannot spit out step pulses fast
enough to
> keep you happy, and or your "gearing" is way off and you need to
speed it
> up. To me, the multiplier feature of the 210 doesn't seem all that
useful.
> Am I missing something?
>
> Regards,
>
> Paul R. Hvidston, N6MGN
> ACKSYS Engineering
> Upland, CA
> ----- Original Message -----
> From: "Guy Sirois" <guys@w...>
> To: <CAD_CAM_EDM_DRO@y...>
> Sent: Monday, February 25, 2002 2:05 PM
> Subject: RE: [CAD_CAM_EDM_DRO] Stepper Math
>
>
> > Yes, Sean.
> >
> > the drives can change the number of steps it takes for one
revolution of
> > the motor.
> >
> > The common motor is a 200 step/revolution as a base value. When
it is
> being
> > driven by a drive that runs in "Full step mode", it will take 200
pulses
> to
> > make it turn one rev. This is rarely seen/used.
> >
> > You are most likely to encounter a drive that runs in "Half-step
mode",
> > meaning it will take 400 pulses to make one rev. The motor just
follows
> that
> > and stops at every half-step instead of every full-step of its
200 steps.
> >
> > Likewise, there are drives that run in quarter-step, eight-step,
or tenth
> > step like the Gecko G201. You are now at 2000 pulses per
revolution. Your
> > motor runs 10 times slower than on a full-step drive but it is 10
times
> more
> > precise (theoretically) and most importantly, much more than 10
times
> > smoother.
> >
> > The speed versus resolution is a compromise you have to make, but
the
> > smoothness factor of fractional step drives is maybe more
important,
> > depending on your application.
> >
> > Hope this helps,
> > Guy
> >
> >