CNC router x axis homing issue

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rhscdn
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Junior Member

11 Sep 2025 02:12 #334803 by rhscdn

CNC router x axis homing issue was created by rhscdn

I am having a little trouble trying to understand axis homing that I am hoping someone can explain. I am trying to use my minimum x-axis limit switch for homing. It is currently working ok as a limit switch.

From the documentation , I have SEARCH_VEL negative and LATCH_VEL negative so I expected the homing sequence to follow the 2nd diagram, i.e.

move in the negative x direction at SEARCH_VEL speed until the home/limit switch is activated,
back off the home/limit switch at SEARCH_VEL speed in the positive x direction,
move in the negative x direction at LATCH_VEL speed until the home/limit switch is activated,
move in the positive direction at HOME_FINAL_VEL to the home position.

However, in the last step (4), the tool moves opposite to what I expect (the negative x direction) and crashes into the endstop.

Relevant settings are:

machine.hal

...
# --- MIN-X ---
net min-x <= hm2_7i96s.0.inm.00.input-00
...
# https://www.linuxcnc.org/docs/html/config/ini-homing.html#_home_ignore_limits
# If you do not have a separate home switch set HOME_IGNORE_LIMITS to YES
# and connect the limit switch signal to the joint home switch input in HAL
# Original
#net x-home-sw => joint.0.neg-lim-sw-in
net min-x => joint.0.neg-lim-sw-in joint.0.home-sw-in
net x-pos-limit => joint.0.pos-lim-sw-in

machine.ini

[AXIS_X]
MAX_VELOCITY = 5.483333333333333
MAX_ACCELERATION = 4.0
MIN_LIMIT = -0.001
MAX_LIMIT = 39.0

[JOINT_0]
TYPE = LINEAR
FERROR = 0.5
MIN_FERROR = 0.05
MAX_VELOCITY = 5.483333333333333
MAX_ACCELERATION = 4.0
STEPGEN_MAXVEL = 6.85
STEPGEN_MAXACCEL = 5.00
P = 1000.0
I = 0.0
D = 0.0
FF0 = 0.0
FF1 = 1.0
FF2 = 0.0
BIAS = 0.0
DEADBAND = 0.0
MAX_OUTPUT = 0.0
# these are in nanoseconds
DIRSETUP = 6000
DIRHOLD = 6000
STEPLEN = 3000
STEPSPACE = 3000
STEP_SCALE = 2037.25
MIN_LIMIT = -0.001
MAX_LIMIT = 39.0
HOME_SEARCH_VEL = -0.2
HOME_LATCH_VEL = -0.05
HOME_FINAL_VEL = 0.1
HOME = 1.0
HOME_OFFSET = 5.0
HOME_IGNORE_LIMITS = YES
HOME_IS_SHARED = 1
HOME_SEQUENCE = 2

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rhscdn
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Junior Member

11 Sep 2025 02:58 #334806 by rhscdn

Replied by rhscdn on topic CNC router x axis homing issue

I should also say that I'm using a 7i96s and originally used pncconf to generate these, In the wizzard, I specified my inputs 0,1,2 as X,Y,Z Limit Switches. Would it be better to specify these as Home Switches?

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