YASKAWA Sigma-7 SGD7S Series - Page 656

Problem Possible Cause Confirmation Correction Reference
The P-OT/N-OT (For-
ward Drive Prohibit or
Reverse Drive Pro-
hibit) signal malfunc-
tioned.
Check for fluctuation
in the external power
supply (+24 V) voltage
for the input signals.
Eliminate fluctuation
from the external
power supply (+24 V)
voltage for the input
signals.
–
Check to see if the
operation of the over-
travel limit switches is
unstable.
Stabilize the operating
condition of the over-
travel limit switches.
–
Check the wiring of
the overtravel limit
switches (e.g., check
for cable damage and
loose screws).
Correct the wiring of
the overtravel limit
switches.
–
There is a mistake in
the allocation of the P-
OT or N-OT (Forward
Drive Prohibit or
Reverse Drive Pro-
hibit) signal in Pn50A
= n.X or Pn50B
= n.X.
Check to see if the P-
OT signal is allocated
in Pn50A = n.X.
If another signal is
allocated in Pn50A =
n.X, allocate the
P-OT signal instead.
Ä Chap. 6.11 ‘Over-
travel and Related
Settings’ page 160
Check to see if the N-
OT signal is allocated
in Pn50B = n.X.
If another signal is
allocated in Pn50B =
n.X, allocate the
N-OT signal instead.
The selection of the
Servomotor stopping
method is not correct.
Check the servo OFF
stopping method set
in Pn001 = n.X
or Pn001 = n.X.
Select a Servomotor
stopping method other
than coasting to a
stop.
Ä Chap. 6.11.4 ‘Motor
Stopping Method for
Overtravel’ page 162
Check the torque con-
trol stopping method
set in Pn001 =
n.X or Pn001 =
n.X.
Select a Servomotor
stopping method other
than coasting to a
stop.
Improper Stop Posi-
tion for Overtravel
(OT) Signal
The limit switch posi-
tion and dog length
are not appropriate.
– Install the limit switch
at the appropriate
position.
–
The overtravel limit
switch position is too
close for the coasting
distance.
– Install the overtravel
limit switch at the
appropriate position.
–
Position Deviation
(without Alarm)
Noise interference
occurred because of
incorrect Encoder
Cable specifications.
Turn OFF the power
supply to the servo
system. Check the
Encoder Cable to see
if it satisfies specifica-
tions. Use a shielded
twisted-pair wire cable
or a screened twisted-
pair cable with con-
ductors of at least
0.12 mm
2
.
Use cables that satisfy
the specifications.
–
Sigma-7 Series SERVOPACKs
Maintenance
Troubleshooting Based on the Operation and Conditions of the Servomotor
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