Steve:
> No, I think you misunderstand - If commanded is say, 400 and actual is
420 it takes ages. If commanded is 400 and actual is 400 adder starts
instantly and doesn't do this crazy counting to many millions.
Even this should not matter. The only numbers that are important are
"Normal SPinCount" and "Current SpinCount"...
I've just done a little more testing and it may well be that there is
some false triggering, the spindle speed is absolutely constant,
measured with both a mechanical and an external hand held tacho.
The external rev counters (which I borrowed) don't always agree with
Mach2!!
The speed Mach2 senses sometimes jumps slightly, the accel/decel
lights are always cycling, even though the spindle isn't varying in
speed.
This is a good sign, the acc and dec lights mean that one cycle is
slightly longer and the next slightly smaller. When your measureing to 20us
in resoution, no speed variation would benecessary for this to happe,the
lights are gone in the newest version...
>
? Perhaps the slot is too wide, or more
likely narrow?
I'm wondering, as my pulses are quite narrow, that it's sometimes
triggering on the "wrong" edge?
As long as a pulse is longer than 1 interrupt time ( 40us at 25Khz), it
shoudl grab it...
The system is always counting the number of interrupts from leading edge
of
the index pulse to leading edge of the next pulse. It averages these over
a
5 rotation period at all times..
Would it matter if the pulse is inverted? (then triggering on trailing
edge).
Nope, no matter, as long as the negative portion went low for at least
20us. (I think, I will check this...Just make sure low active is set if it
goes neg and hi if not..
Can't do any more tonight, but will test spindle pulses some more
tomorrow, with much longer time period on freq counter, only did a few
one minute tests at 400, 500 and 600rpm.
--
Thanks for the tests,
Art
Steve Blackmore
