On 4/10/2019 11:31 AM, andy pugh wrote:
On Wed, 10 Apr 2019 at 17:12, Danny Miller <dan...@austin.rr.com> wrote:
I have been wondering- can emcmot be separated from the HAl and emctask
and become a true dedicated realtime stage to control the joints?
I suspect not as it stands. This is based on the observation that
motmod is a HAL module.
?
http://wiki.linuxcnc.org/cgi-bin/wiki.pl?EMC_Components
Shows EMCMOT as a discrete module, and emcmot.c and emcmot.h are
supposed to be discrete files. The motor PWMs and switch IO is under
the realtime veil, which is easy to integrate into hw.
I see the shared memory (inherently fast) with EMCTASK, but I doubt
ethernet latency would be a dealbreaker. Correct me if I'm wrong.
I also have this diagram:
https://www.researchgate.net/figure/EMCMOT-Structure_fig2_265199849
which depicts the HAL with servo feedback (not essential as we use
steppers) and fault/limit switches going to EMCMOT on a separate port.
That seems functionally identical just a different artistic style.
I'd like to be able to integrate 2.8's circular arc blending trajectory
planning into laser cutter and 3d printer control HW. This might
eventually mean EMCTASK is also on hardware and Windows machines or
anything else with whatever bastard config they happen to have installed
can keep it fed with G-code. The subset of common g-codes may be
preferable, you don't need G73 high speed peck drills or G74 left-hand
tapping cycle for 3D printers or laser cutters. I don't think any of
the CAM pkgs would even generate subroutines which is best to leave
unsupported as it's nonlinear.
Ideally, a bit ambitious, and not entirely within G-code, but I'd like
to take a stab at nontrapezoidal acceleration profiles and multiple
acceleration models. This would be useful- in transitioning from the
end of a laser cut path into a rapid, it's "as fast as the machine can
go" once the beam is off, whereas in starting a cut you may want a
smoother stop because of belt stretch causing some oscillation that
would persist briefly as the beam turns on. With lasers you typically
want to fullstop briefly at the start and end of every cut, but then why
slam it to a rushed G0 stop only to do a
G0-to-cold-dwell-then-powerup-dwell-then-go.
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