3.1 FT82 SERVOPACKs with Analog Voltage/Pulse Train References
3.1.7 Troubleshooting Based on the Operation and Conditions of the Servomotor
3
Maintenance
3-47
Overtravel
Occurred
The P-OT/N-OT (Forward
Drive Prohibit or Reverse
Drive Prohibit) signal was
input.
Check the external power
supply (+24 V) voltage for
the input signals.
Correct the external
power supply (+24 V)
voltage for the input
signals.
–
Check the operating con-
dition of the overtravel
limit switches.
Make sure that the
overtravel limit switches
operate correctly.
–
Check the wiring of the
overtravel limit switches.
Correct the wiring of
the overtravel limit
switches.
*
Check the settings of the
overtravel input signal
allocations (Pn50A/Pn50B).
Set the parameters to
correct values.
*
The P-OT/N-OT (Forward
Drive Prohibit or Reverse
Drive Prohibit) signal mal-
functioned.
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 opera-
tion of the overtravel 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 allo-
cation of the P-OT or N-OT
(Forward Drive Prohibit or
Reverse Drive Prohibit) sig-
nal 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 Servo-
motor 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.
*
Check the torque control
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 position and
dog length are not appropri-
ate.
–
Install the limit switch at
the appropriate posi-
tion.
–
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.
Check the Encoder Cable
to see if it satisfies speci-
fications. 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.
Check the length of the
Encoder Cable.
The Encoder Cable
length must be 50 m
max.
–
Noise interference occurred
because the Encoder Cable
is damaged.
Check the Encoder Cable
to see if it is pinched or
the sheath is damaged.
Replace the Encoder
Cable and correct the
cable installation envi-
ronment.
–
Continued on next page.
Continued from previous page.
Problem
Possible Cause
Confirmation
Correction
Reference
