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  • ffffrf
  • ffffrf
29 Apr 2025 21:19

Frustrated - cant figure out how to display encoder speed on any gui for lathe

Category: Gmoccapy

So...I am not 100% sure if this is a gmoccapy issue or a deeper linuxcnc issue but I suspect it is something with the GUI.

A long time ago, I made a generic XZ lathe + analog motor + external incremental rotary encoder HAL/INI via AXIS gui. All worked well, and the side of the AXIS GUI displayed the spindle speed bar plus the red button indicating if spindle was at speed or not. It worked correctly.

However, now I have build a different machine: a custom XZC lathe with a STEPGEN controlled servo spindle, and I am trying to simply have the same thing work where when I run the servo motor, I see the RPM based on what the encoder sees. The wiring of this machine is all the same as the last one minus a C axis and servo.

BUT... NOTHING I do allows me to see this information and I cant figure out what it is. Axis GUI does not display any spindle speed displays. I thought maybe it was an AXIS issue and switched to gmocappy, which I atleast was now seeing a spindle speed bar. However, when i turn the spindle on, I just see the default comanded rpm instead of what the encoder sees.

This is the relevant section of the HAL:


#Original 4 lines from "MODLATHE" working hal/ini
setp     lowpass.spindle.gain 1.000000
net spindle-vel-fb-rpm => abs.spindle.in
net spindle-vel-fb-rpm-abs abs.spindle.out => lowpass.spindle.in
net spindle-fb-rpm-abs-filtered lowpass.spindle.out

net spindle-actual-rpm spindle-fb-rpm-abs-filtered => gmoccapy.spindle_feedback_bar
net spindle-actual-rpm spindle-fb-rpm-abs-filtered => gmoccapy.spindle_at_speed_led

#above 2 lines added in attempt to get gmocappy to display the correct 


HOWEVER, any time I try to run the program, I get "spindle-fb-rpm-abs-filtered" but no matter what input i place into those two lines it says that pin does not exist

HALMETER: IN halmeter, I see abs.spindle.out and abs.spindle.in working correctly. Also, if I remove the belt from my encoder and monitor spindle-at-speed, if I command the spindle to move and then manually rotate the encoder, I get the value to change from true to false - which makes me think my setup is working and its more of a GUI issue?


Can someone help me figure out what I am doing wrong and how I can get gmoccapy to display my encoder RPM and if the spindle is at speed or not correctly?

my MODLATHE hal/ini is my original machine that had the working gui to show the encoder rpm and if the spindle was at speed or not.
my C+TURN axis hal/ini is my new custom machine i am trying to set up
  • scotta
  • scotta's Avatar
29 Apr 2025 21:12

Remora - Rpi Software Stepping Using External Microcontroller via SPI

Category: Computers and Hardware

Nice work! Using PIO board variants might be the way to go. That's how Marlin has managed it and it's so much like how Mbed uses custom targets. They use some custom python scripts to make the magic work.
  • PCW
  • PCW's Avatar
29 Apr 2025 20:57 - 29 Apr 2025 22:25
Replied by PCW on topic LinuxCNC S-Curve Accelerations

LinuxCNC S-Curve Accelerations

Category: General LinuxCNC Questions

OK it does work, my test configuration was missing the
default/max velocity and accel settings in the TRAJ section
of the .ini file. This (missing values) seems to work with the
standard TP (maybe it has some kind of working defaults)
but fails with  the S-Curve TP.

Note that I can still trigger following errors with actual
hardware as  the S-Curve TP does not seem to obey joint
acceleration constraints.

The TRAJ and joint accelerations are both set to 200 here:

 

But that acceleration is exceeded (and trips a following error when
it exceeds the hardware's accel limit of 240)
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