15.4 Troubleshooting Based on the Operation and Conditions of the Servomotor
15-57
15
Maintenance
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 of incorrect Encoder
Cable specifications.
Turn OFF the Servo Sys-
tem. Check the Encoder
Cable to see if it satisfies
specifications.
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 Servo Sys-
tem. 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.
Turn OFF the Servo Sys-
tem. 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
subjected to excessive noise
interference.
Turn OFF the Servo Sys-
tem. 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.
Turn OFF the Servo Sys-
tem. 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 Servo Sys-
tem. Check to see if there
is noise interference on
the I/O signal line from
the encoder or Serial
Converter Unit.
Implement counter-
measures against noise
for the encoder or
Serial Converter Unit
wiring.
–
Continued on next page.
Continued from previous page.
Problem
Possible Cause
Confirmation
Correction
Reference
