Re: [CAD_CAM_EDM_DRO] DeskNC Windows version

Alan:

Actually 8000 pulses per second is pretty good. EMC for example, at my last
reading was limited to 4096 steps per second. Even DOS or normal Linux is
hard pressed to exceed 8192 pulses per second and maintain any real-time
capabilities. This is due to the fact that you can olny interrupt the system
at a rate of 8192 times per second without using some kind of timing
generator. The last time I checked on the EMC kernal, it interrupted at 8192
but because it only set a pulse on one interrupt, then cleared it on the
next, its final frequency was 4096 steps per second. (I'm sure I'll get
corrected if I'm wrong :) )
The P6 chips with a built in ASIC can be programmed to interrupt at
any rate you wish. Since it uses the CPU Clock to achive this, It uses a
timing of 1.2GHZ on a 1.2GHZ machine. And with multiple timers on the chip,
it means you could set an X,Y and Z Timer at different and dynamically
changing frequencies to step the motors. This gives a much higher speed, and
an increased resolution in terms of the asyncronous nature. The problem is
legacy, even though its possible to probably beat the performance of those
black box pulsing units, most people are not using a 1.2GHZ machine for
their CNC work. (But we'll get there eventually). Using the CPU clock for
timing makes things much better. My 500Mhz pentium can time to about
2nanoseconds for accuracy of the pulse. It makes Master5 smoother than most,
though you can never really achieve linux real-time smoothness due to its
pre-emptive interrupt capability.

PS: Just got a wingman extreme joystick hooked up to Master5, kinda neat,
throttle for feed overRide, Joystick for multiple speed Jogging.....kewl..

Art

----- Original Message -----
From: "Alan Marconett KM6VV" <KM6VV@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Wednesday, April 18, 2001 2:49 PM
Subject: Re: [CAD_CAM_EDM_DRO] DeskNC Windows version


> Hi Art,
>
> Thanks for the reply. I'd heard that parallel was impossible, and
> serial possible under windows. Is there any EPP/ECP support under
> windows? Might that work better, similar to serial? But then, it
> wouldn't be a "simple" parallel port, I guess!
>
> By 8000 PPS, are assuming a 133Mhz Pentium class machine on Windoz? I
> thought I'd heard higher numbers, must be for Linux or DOS.
>
> I'd also like to hear about the P6 instruction(s) that aid in
> timing/step generation.
>
> Alan KM6VV
>
>
> Art Fenerty wrote:
> >
> > Alan:
> >
> > When sending to a serial port from windows, you don't hang the
system
> > as much. You simply send a series
> > of commands and let the intelligent box do the rest. Most windows
software
> > suffers greatly when sending to the parrallel port due to the time
involved.
> >
> > ""Sounds like a FlashCut!"" -- It is, thats just how flashcut does it
for
> > the most part. It tends to make it very smooth and is a good solution
for
> > the money.Without a black box, you really can't get higher than 8000
> > Pulses/Sec.
> >
> > Getting Master5 to be smooth under windows was a real challenge and
it's
> > easy to see why Black box idea's are starting to proliferate. You just
can't
> > go faster than 8000 pulses per second without such a black box, although
> > that may change under the P6 series chips. My experiments show that
variable
> > asynchronous velocities are possible with P6 processors at quite a
speed. I
> > may try to implement such a system in a year or so. But it will take
awhile
> > for most peoples computers to catch up with the latest motherboards. I
have
> > enough problems with the number of people out there using 133's.
> >
> > Art
>
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