On Sat, 25 Apr 2020, David Berndt wrote:
Date: Sat, 25 Apr 2020 03:23:20 -0400
From: David Berndt <ber...@uberwin.com>
Reply-To: "Enhanced Machine Controller (EMC)"
<emc-users@lists.sourceforge.net>
To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net>
Subject: Re: [Emc-users] Encoder reset on homing to index
After a few more hours tonight putzing around with this thing. Here's where
I'm at.
I've wired up the shared index. It completes both the encoder's index-enable
cycles. encoder.NRotary.position and encoder.nLinear.position both reset to
~0. Home is also at 0 as is homeoffset, so once index is found there should
be no need for the axis to move. However it takes off and gets caught by a
fairly strict ferror.
If I then home it again the result seems to be close enough that the small
post-index-enable completion jump is within f-error. The axis moves a few
.001" and settles. I'm not sure what's causing this jump in the first/second
homing. Because of the ferror the first homing attempt does not actually
complete the homing cycle, ishomed is not set.
For the homing thing, I may setup a mux to turn off the pid.yLinear.output.
Maybe leave it off until everythings homed, or everythings homed + some time,
or some other benchmark. My machine spends very little of it's time in an
unhomed state and the control tends to stay on 99% of the time so
homing/rehoming isn't really much of a priority. Or maybe abandon indexed
homing.
It would also be nice to be able to feed pid.yLinear.feedback into
axis.1.motor-pos-fb. But that's a recipe for the axis taking off/tripping
ferror instantly. I'm not sure why, I can watch the pid.yRotary.feedback and
pidyLinear.feedback and they're quite close to each other. I think this works
fine pre-homed and breaks after homing but I'd have to re-run that experiment
to be sure. Seeing the machine @actual position being off a few thou is
really disconcerting. I can always press the @ to switch to machine
commanded, which is (hopefully, if the linear is more accurate) much closer
to reality.
-Dave
Is the index enable signal wired to both PID components in hal?
Also What is the thread order?
(it should be hardware_read, motion, PID, hardware_write)
Peter Wallace
Mesa Electronics
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