10 Troubleshooting
10-28
Improper Position
to Stop by
Overtravel (OT)
Signal
Improper limit switch position and
dog length
−
Install the limit switch at the
appropriate position.
The overtravel limit switch position
is too short for the coasting
distance.
−
Install the overtravel limit switch at
the appropriate position.
Position Error
(Without Alarm)
Noise interference due to improper
encoder cable specifications
The encoder cable must be tinned
annealed copper twisted-pair or
shielded twisted-pair cable with a
core of 0.12 mm
2
min.
Use encoder cable with the speci-
fied specifications.
Noise interference due to length of
encoder cable
Check the encoder cable length.
The encoder cable length must be
no more than 20 m.
Noise influence due to damaged
encoder cable
Check if the encoder cable is bent or
if its sheath is damaged.
Replace the encoder cable and cor-
rect the encoder cable layout.
Excessive noise interference to
encoder cable
Check if the encoder cable is bun-
dled with a high-current line or near
a high-current line.
Change the encoder cable layout so
that no surge is applied.
FG potential varies because of
influence of machines such as weld-
ers at the servomotor.
Check if the machines are correctly
grounded.
Ground machines correctly, and
prevent diversion to the FG at the
PG side.
SERVOPACK pulse count error due
to noise
Check if the input/output signal line
from the encoder is influenced by
noise.
Take measures against noise in the
encoder wiring.
Excessive vibration and shock to
the encoder
Check if vibration from the machine
occurred or servomotor installation
is incorrect (mounting surface accu-
racy, fixing, alignment, etc.).
Reduce the machine vibration or
mount the servomotor securely.
Unsecured coupling between
machine and servomotor
Check if a position error occurs at
the coupling between machine and
servomotor.
Secure the coupling between the
machine and servomotor.
Noise interference due to improper
I/O signal cable specifications
The I/O signal cable must be
twisted-pair or shielded twisted-pair
cable with a core of 0.12 mm
2
min.
and tinned annealed copper twisted
wire.
Use input signal cable with the
specified specifications.
Noise interference due to length of
I/O signal cable
Check the I/O signal cable length.
The I/O signal cable length must be
no more than 3 m.
An encoder fault occurred. (The
pulse count does not change.)
− Replace the servomotor.
A SERVOPACK fault occurred. − Replace the SERVOPACK.
Servomotor
Overheated
Ambient temperature too high
Measure the servomotor ambient
temperature.
Reduce the ambient temperature to
40°C or less.
Servomotor surface dirty Visually check the surface. Clean dust and oil from the surface.
Servomotor overloaded Check the load status with monitor.
If overloaded, reduce load or
replace with larger capacity servo-
motor.
Problem Probable Cause Investigative Actions Corrective Actions
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