YASKAWA E-V Series User Manual page 319

9 Troubleshooting
Problem
Overtravel (OT)
(Movement over
the zone specified
by the host
controller)
9-26
Probable Cause
An overtravel signal is output (P-
OT (CN1-42) or N-OT (CN1-43)) is
at H.
The overtravel signal does not oper-
ate normally (P-OT or N-OT signal
sometimes changes).
Incorrect P-OT/N-OT signal selec-
tion
Incorrect servomotor stop method
selection
Improper overtravel position setting
Noise interference due to improper
serial converter unit connection
cable specifications
Noise interference because the
serial converter unit connection
cable distance is too long.
Noise influence due to damaged
serial converter unit connection
cable
Excessive noise interference to
serial converter unit connection
cable
FG electrical potential varies by
influence of such machines on the
servomotor side as welders.
SERVOPACK pulse count error due
to noise
Excessive vibration and shock to
the serial converter unit
Serial converter unit fault
SERVOPACK fault
Investigative Actions
Check if the voltage of input signal
external power supply (+24 V) is
correct.
Check if the overtravel limit switch
(SW) operates properly.
Check if the overtravel limit switch
(SW) is connected correctly.
Check the fluctuation of the input
signal external power supply (+24
V) voltage.
Check if the overtravel limit switch
(SW) activate correctly.
Check if the overtravel limit switch
wiring is correct. (check for dam-
aged cables or loosen screws.)
Check the P-OT signal mapping
(Pn50A.3).
Check the N-OT signal mapping
(Pn50B.0).
Check if "coast to stop" in servo
OFF status is selected.
Check if "coast to stop" in force
control mode is selected.
Check if the distance to the position
of OT (overtravel) is too short con-
sidering the coasting distance.
The serial converter unit connection
cable specifications must be:
Twisted-pair or twisted-pair
shielded wire with core
2
0.12 mm min. and tinned annealed
copper twisted wire.
The wiring distance must be 20 m
max.
Check if the serial converter unit
connection cable is bent or its
sheath is damaged.
Check if the serial converter unit
connection cable is bundled with a
high-current line or near high-cur-
rent line.
Check if the machine is correctly
grounded.
Check if the I/O signal cable from
the serial converter unit is influ-
enced by noise.
Check if machine vibration
occurred or serial converter unit
mounting such as mounting surface
precision, fixing is incorrect.
−
−
Corrective Actions
Connect to the external +24 V
power supply.
Correct the overtravel limit SW.
Correct the overtravel limit SW wir-
ing.
Stabilize the external +24 V power
supply voltage.
Adjust the overtravel limit SW so
that it operates correctly.
Correct the overtravel limit SW wir-
ing.
Correct the setting of P-OT signal
mapping (Pn50A.3).
Correct the setting of N-OT signal
mapping (Pn50B.0).
Check Pn001.0 and Pn001.1.
Check Pn001.0 and Pn001.1.
Correct the OT position.
Use serial converter unit connection
cable with the specified specifica-
tions.
The serial converter unit connection
cable distance must be within the
specified range.
Correct the serial converter unit
connection cable layout.
Change the serial converter unit
connection cable layout so that no
surge voltage is applied.
Ground the machine separately
from encoder side FG.
Take a measure against noise for the
serial converter unit wiring.
Reduce the machine vibration or
mount the serial converter unit
securely.
Replace the serial converter unit.
Replace the SERVOPACK.