YASKAWA SGD7S Product Manual page 469

Problem Possible Cause
Noise interference occurred
because of incorrect Encoder
Cable specifications.
Noise interference occurred
because the Encoder Cable
is too long.
Absolute
Encoder
Position
Deviation
Noise interference occurred
Error (The
because the Encoder Cable
position
is damaged.
that was
saved in the
The Encoder Cable was sub-
host con-
ject to excessive noise inter-
troller when
ference.
the power
was turned
There is variation in the FG
OFF is dif-
potential because of the
ferent from
influence of machines on the
the posi-
Servomotor side, such as a
tion when
welder.
the power
was next
There is a SERVOPACK
turned ON.)
pulse counting error due to
noise.
The encoder was subjected
to excessive vibration or
shock.
A failure occurred in the
encoder.
A failure occurred in the SER-
VOPACK.
12.5 Troubleshooting Based on the Operation and Conditions of the Servomotor
Confirmation
Check the Encoder Cable
to see if it satisfies speci-
fications. Use shielded
twisted-pair cables or
screened twisted-pair
cables with conductors of
at least 0.12 mm
(stranded wire).
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
I/O signal line from the
encoder or Serial Con-
verter Unit.
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).
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Continued from previous page.
Correction
Use cables that satisfy
the specifications.
2
• 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.
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 or
Serial Converter Unit
wiring.
Reduce machine vibra-
tion. Improve the
mounting state of the
Servomotor or linear
encoder.
Replace the Servomo-
tor or linear encoder.
Replace the SERVO-
PACK.
Continued on next page.
Reference
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12
12-63