5.7 Troubleshooting Based on the Operation and Conditions of the Servomotor
5-49
5
Maintenance
Overtravel
Occurred
There is a mistake in
the allocation of the P-
OT or N-OT (Forward
Drive Prohibit or
Reverse Drive Prohibit)
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 allo-
cated in Pn50A
=n.X
, allocate the P-
OT signal instead.
*
Check to see if the N-OT
signal is allocated in Pn50B
= n.
X.
If another signal is allo-
cated in Pn50B
=n.
X, allocate the N-
OT signal instead.
The selection of the
Servomotor stopping
method is not correct.
Check the servo OFF stop-
ping method set in Pn001 =
n.
X or Pn001 =
n.
X
.
Select a Servomotor stop-
ping method other than
coasting to a stop.
*
Check the torque control
stopping method set in
Pn001 = n.
X or Pn001
= n.
X
.
Select a Servomotor stop-
ping 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 conductors of at least
0.12 mm
2
.
Use cables that satisfy the
specifications.
–
Noise interference
occurred because the
Encoder Cable is too
long.
Turn OFF the power supply
to the servo system.
Check the length of the
Encoder Cable.
The Encoder Cable length
must be 50 m max.
–
Noise interference
occurred because the
Encoder Cable is dam-
aged.
Turn OFF the power supply
to the servo system.
Check the Encoder Cable to
see if it is pinched or the
sheath is damaged.
Replace the Encoder
Cable and correct the
cable installation environ-
ment.
–
The Encoder Cable
was subjected to
excessive noise inter-
ference.
Turn OFF the power supply
to the servo system.
Check to see if the Encoder
Cable is bundled with a
high-current line or installed
near a high-current line.
Correct the cable layout so
that no surge is applied by
high-current lines.
–
There is variation in the
FG potential because
of the influence of
machines on the Ser-
vomotor side, such as
a welder.
Turn OFF the power supply
to the servo system.
Check to see if the
machines are correctly
grounded.
Properly ground the
machines to separate
them from the FG of the
encoder.
–
There is a SERVOPACK
pulse counting error
due to noise.
Turn OFF the power supply
to the servo system.
Check to see if there is
noise interference on the I/O
signal line from the encoder
or Serial Converter Unit.
Implement countermea-
sures against noise for the
encoder wiring or Serial
Converter Unit wiring.
–
Continued on next page.
Continued from previous page.
Problem
Possible Cause
Confirmation
Correction
Reference
