RE: [CAD_CAM_EDM_DRO] Re: DOS/EMC aka DeskNCrt now freely available

I don't know the direct answer to your question, but the question is
actually a little more complex. EMC will put out a very high pulse rate, but
there can be some usability problems. IF using steppermod you will get lots
of steps, but the pacing of the steps is ragged and as your speed climbs
this uneven pacing can cause stalling and resonance problems. If you use
freqmod you will get much more even pulses, but it works on the basis of a
generated frequency and pulses are output based upon a pattern from this
reference frequency. For example, if you are going along and you are
outputting a step every 4th pulse of the base frequency and you want to go
faster it will switch to maybe every third pulse of the base. This gives
very even steps, but the problem becomes that the jump between possible
patterns can be more of an acceleration than the motors can deal with. The
faster the system you are using the higher a frequency you can run the
reference at and the higher the speed at which the jumps become too large.
On my K6 (450 or 500 don't remember) and with 4000 steps per inch I was
running into this problem in the 80 - 90 ipm range with freqmod. Using
steppermod I was limited to 40 ipm or so as I would get a resonance at about
48 ipm.

Now if you are using the Gecko G3X0 servos none of this matters as it just
uses the step count to drive one side of a comparator to generate the error
signal and doesn't care if the pulses are evenly paced. So, you can just use
steppermod and go for all the steps you want (OK, it didn't want to go to
4,000,000 steps per minute on a P200, 1000 line encoder, 2:1 belt reduction,
5 tpi screw, and 100 ipm, that would be more appropriate for the pulse
multiplied Gecko products).

Long answer, but hope it sheds some light on the considerations. Of course,
Jon Elson has developed a hardware pulse generator that eliminates all these
problems and will let EMC on a slow computer put out incredible evenly paced
pulse rates.

Tim
[Denver, CO]

> Can anyone tell me the maximum pulse rate that EMC can provide on a
> 300 to 400 Mhz Pentium II?
>
> How about DeskNCrt?
>
> Tom Murray
>
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