YASKAWA SGM7D-30F Product Manual page 161

3.2 FT82 SERVOPACK with MECHATROLINK-II Communications References
3.2.7 Troubleshooting Based on the Operation and Conditions of the Servomotor
Problem
Abnormal
Noise from
Servomotor
3-92
Possible Cause
Noise interference occurred
because of incorrect I/O sig-
nal cable specifications.
Noise interference occurred
because an I/O signal cable
is too long.
Noise interference occurred
because of incorrect Encoder
Cable specifications.
Noise interference occurred
because the Encoder Cable
is too long.
Noise interference occurred
because the Encoder Cable
is damaged.
The Encoder Cable was sub-
jected to excessive noise
interference.
There is variation in the FG
potential because of the
influence of machines on the
Servomotor side, such as a
welder.
There is a SERVOPACK
pulse counting error due to
noise.
The encoder was subjected
to excessive vibration or
shock.
A failure occurred in the
encoder.
Confirmation
Check the I/O signal
cables to see if they sat-
isfy specifications. Use
shielded twisted-pair wire
cables or screened
twisted-pair cables with
conductors of at least
2
0.12 mm .
Check the lengths of the
I/O signal cables.
Make sure that the rotary
or Linear Encoder Cable
satisfies the specifica-
tions. Use a shielded
twisted-pair wire cable or
a screened twisted-pair
cable with a conductors
2
of at least 0.12 mm .
Check the length of the
Encoder Cable.
Check the Encoder Cable
to see if it is pinched or
the sheath is damaged.
Check to see if the
Encoder Cable is bundled
with a high-current line or
installed near a high-cur-
rent line.
Check to see if the
machines are correctly
grounded.
Check to see if there is
noise interference on the
signal line from the
encoder.
Check to see if vibration
from the machine
occurred. Check the Ser-
vomotor installation
(mounting surface preci-
sion, securing state, and
alignment).
–
Continued from previous page.
Correction Reference
Use cables that satisfy
–
the specifications.
The I/O signal cables
must be no longer than
–
3 m.
Use cables that satisfy
–
the specifications.
Rotary Servomotors:
The Encoder Cable
–
length must be 50 m
max.
Replace the Encoder
Cable and correct the
–
cable installation envi-
ronment.
Correct the cable lay-
out so that no surge is
–
applied by high-current
lines.
Properly ground the
machines to separate
–
them from the FG of
the encoder.
Implement counter-
measures against noise
–
for the encoder wiring.
Reduce machine vibra-
tion. Improve the
–
mounting conditions of
the Servomotor.
Replace the Servomo-
–
tor.
Continued on next page.