"Randy A." wrote:
> Dave:
> I too do CNC machine repair, install and retro fits with PC based controls.
> I have asked this same question several times and in almost every case the
> answers have been to use a quadrature decoder such as the HP or U.S. Digital
> ones to do it.  If you get ANY information that will allow us to input rates
> up to 60 KHz which would allow the use of a 1000 ppr incremental encoder to
> be used with a servo drive that runs at 3500 rpm.  The pulse rate seems to be
> the problem.

I would think so. Have you looked at your pulse train at speed with a
scope? If you are getting a good signal (at the end of the cable you
plan to use), then you can readily build a FPGA based interface.
There was an article in a very old magazine called "Robotics Age" circa
1980 on doing exactly that. Wasn't that complex. With today's improved
programmable logic, it should be much easier. It's basically a 4 state
diagraph clocking an up/down counter. You could also do it with
discretes
(yuk).

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