On Wed, 03 Sep 2003 14:34:14 -0300, you wrote:
Thanks, the numbers help. It seems to indicate that the "normal" spincount
is too low and the current is almost 3 times the normal. This means a 3:1
reduction in speed is being sensed. This is obviously wrong and probably a
bug on my part due to spindle speed step/dir. I suspect the delay is
causing a screwed up number being computed.
Hi Art - just a follow up on painting the sensor disc, after that was
done Mach2's measured rpm changed slightly for the same spindle speed
settings, measured rpm dropped, which hints that the sensor was
picking up reflections. I can't see them on the old analogue scope, I
can only get it to trigger on the major pulses.
Moving the slotted disc very close to the detector gives a "low"
reading, moving it towards the emitter gives a higher reading for the
same selected motor revs. We are talking +/- 80 rpm!!
The only explanation I can get from this is Mach2 is so sensitive it
is triggering sometimes on the leading and trailing edges of the same
pulse giving spurious rpm readings. The actual spindle speed is NOT
changing.
I tested this by setting the speed to 1000 rpm. Moving the disc has
less effect, still there but only 20 rpm or so.
The sensor disc slot is about 2mm wide on about a 40mm radius (not
measured). The only options, in order of preference, I have is,
de-rate the emitter voltage, close the gap or change the sensor and
hope they help, but my gut feeling is that Mach2 maybe too sensitive?
What do you think?
--
Steve Blackmore
