Re:Re: Encoders

Gecko step and direction servo drives don't seem to care about the pulse
spacing. The pulses just drive an accumulator that is used to drive an
comparator. The other side of the comparator is driven by an accumulator
that is drive from the encoder. The comparator provides the error signal
to drive the servo amp section (this is not a detailed analysis of how a
G320 works, just a high level view). So you don't have the problems you
see with steppers being driven with an erratic pulse.

As far as the encoder count, I aim for a step increment of about .0001 -
.0002" with G320s. So you have to look at any reduction between the
motor and the screw along with the screw pitch and figure out what you
should use.

Tim
[Denver, CO]
Visual Mill 5.0 Basic at a price too low to post!

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----------------------Original message-----------
If you are driving the screw direct I would not go
any less then 500 cpr = 2000 pulses per revolution
i guess up to 1000 cpr would probably work but may
get close to the limits of the software.
Keep in mind that as you aproch the software limitations
the pulse train spacing will get more erratic and
depending on the tolerance of your drivers and motors to
this you may not be able to get as fast as the software
claims you could theoretically go.
If you are using pulleys or any other form of further reduction
reduce my recommedations by this ratio also.
Good Luck