Greetings Andy;
I'm having a hell of a time rebuilding my GO704 for a different A axis
that involves moving the spindle controls to the spin pins on a 7i76,
getting rid of both pwmgens in my current config.
The problem is the analog i/o sample_hold, I need the digital equ so I
don't have to do a jillion S32-float conversions.
Is there such a critter and I'm too old to see it?
What I need is a detector that compares the state of the spindle.0.out
with the current state of what is sent to hm2_5i25.0.7i76.0.0.spindir pin.
An xor2 does that and I'll use its output as a flipflop clk to clock the
new state into the spindle controller. But I need a sample_hold to hold
the current direction state until other logic has stopped the spindle.
Using motion's signal, which does not stop the spindle when reversing,
slams a 30 amp breaker in the service box but with my old code I'm
inserting a stop delay that doesn't allow the reverse signal thru until
the encoder says its stopped, but I have to use additional delays by
ramping the speed with a linear3 to keep it within the Z axis's ability
to follow for rigid tapping. By taking advantage of Jon's pwm-servo's 4
quadrant control and controlling the motors slowdown and speedups in the
other direction, I recover the energy in the motor, which seriously over
voltages the caps in the spindle power supply for a few milliseconds,
running that 126 volt supply with 2 65 volt caps in series, up to around
170 volts but then uses that energy to accellerate the motor in the
other direction. Currantly this takes around 350 milliseconds from 3000
fwd to -3000 reverse and vice-versa, and because most of it is recovered
by the stop, the shop lights don't blink and I run it on a 20 amp
breaker. Sounds crazy, but I've been doing it for about a decade. Zero
problems.
But I need a digital sample_hold. Can this be cobbled up with flipflops?
Cheers, Gene Heskett.
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author, 1940)
If we desire respect for the law, we must first make the law respectable.
- Louis D. Brandeis
Genes Web page <http://geneslinuxbox.net:6309/>
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