Re: Yaskawa Servo Pack/Motor compatibility

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "vrsculptor"
<vrsculptor@h...> wrote:

>
> > Thanks for the tip, but it won't work. From the webpage: "The
> index
> > signal from the encoder is simply passed straight through from
> input
> > to output with no change."
> >
> > These motor have a special index (encoder C phase) signal, that
> also
> > has to be processed for this to work.
> >
> Arvid,
> Bummer. Never ran into a 3 phase encoder. You can build your own
> divide by 2 circuit for all 3 phases using 2 edge triggered flip
> flops (74F74 ~$0.35). See
> http://physics.uoregon.edu/~torrence/432/notes/notes4.pdf
> You would have to do a reset at power on with a simple RC circuit

to

> insure counter phases.
>
> Roger

It's not a 3 phase encoder, the C phase is still an index phase. But
it's not a single pulse once a turn index, it's a varying duty cycle
pulse train. It varies between (i think) 25%, 50% and 75% duty cycle,
with different phase relationships to the A and B phases thru the
turn. I guess this allows the servo driver to find the absolute angle
of the rotor several times each turn.

So it's not possible to simply divide-it-by-2. I could have done that
with simple discrete logic otherwise, as you say.

Arvid