12.4 Troubleshooting Based on the Operation and Conditions of the Servomotor
12-61
Absolute
Encoder
Position
Deviation
Error (The
position
that was
saved in the
host con-
troller when
the power
was turned
OFF is dif-
ferent from
the posi-
tion when
the power
was next
turned ON.)
Noise interference occurred
because the Encoder Cable
is too long.
Check the length of the
Encoder Cable.
• Rotary Servomotors:
The Encoder Cable
length must be 50 m
max.
• Linear Servomotors:
Make sure that the
Serial Converter Unit
cable is no longer
than 20 m and that
the Linear Encoder
Cable and the Sensor
Cable are no longer
than 15 m each.
–
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.
–
The Encoder Cable was sub-
ject to excessive noise inter-
ference.
Check to see if the
Encoder Cable is bundled
with a high-current line or
installed near a high-cur-
rent line.
Correct the cable lay-
out 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
Servomotor side, such as a
welder.
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.
Check to see if there is
noise interference on the
I/O signal line from the
encoder or Serial Con-
verter Unit.
Implement counter-
measures against noise
for the encoder or
Serial Converter Unit
wiring.
–
The encoder was subjected
to excessive vibration or
shock.
Check to see if vibration
from the machine
occurred.
Check the Servomotor
installation (mounting sur-
face precision, securing
state, and alignment).
Check the linear encoder
installation (mounting sur-
face precision and secur-
ing method).
Reduce machine vibra-
tion. Improve the
mounting state of the
Servomotor or linear
encoder.
–
A failure occurred in the
encoder.
–
Replace the Servomo-
tor or linear encoder.
–
A failure occurred in the
SERVOPACK.
–
Replace the SERVO-
PACK.
–
Host Controller Multiturn
Data or Absolute Encoder
Position Data Reading Error
Check the error detec-
tion section of the host
controller.
Correct the error detec-
tion section of the host
controller.
–
Check to see if the host
controller is executing
data parity checks.
Perform parity checks
for the multiturn data or
absolute encoder posi-
tion data.
–
Check for noise interfer-
ence in the cable
between the SERVO-
PACK and the host con-
troller.
Implement counter-
measures against noise
and then perform parity
checks again for the
multiturn data or abso-
lute encoder position
data.
–
Continued on next page.
Continued from previous page.
Problem Possible Cause Confirmation Correction Reference
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