Mitsubishi Electric MELSEC Q Series Programming Manual page 418

6 POSITIONING CONTROL
(4) Cautions
(a) For the axis which executes the home position return by the limit switch
combined method, if the external input signal has not set in the system
settings, a minor error (error code: 142) will occur and home position return
is not executed.
(b) When the limit switch reverse to home position return direction is turned ON
to OFF, deceleration stop is made, home position return is not completed
and a major error (error code : 1101, 1102) will occur.
(c) Home position return retry function cannot be used in the limit switch
combined method.
(d) If the home position return is executed with the limit switch OFF, it is started
to reverse direction of home position return with creep speed.
(e) When it does not pass (zero pass signal: M2406+20n ON) the zero point
from home position return start to deceleration stop by limit switch OFF, a
minor error (error code: 120) will occur, a deceleration stop is made and
home position return does not end normally. However, when "1 : Not need to
pass motor Z phase after the power supply is switched on" is selected in the
"function selection C-4 (PC17)" of servo parameter (expansion setting
parameter), if the zero point is not passed until from home position return
start to deceleration stop by limit switch OFF, the home position return can
be executed.
(f) Deceleration stop is executed after the limit switch OFF. Set the limit switch
in expectation of deceleration distance.
(g) If the in-position signal (M2402+20n) is turned ON, home position return is
not ended.
(h) When the width is in a zero point, the home position differs from the home
position return by the proximity dog method 1, proximity dog method 2,
count method 1, count method 3, dog cradle method and scale home
position signal detection method.
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