YASKAWA SGD7S-1R9D Product Manual page 537

Problem Possible Cause
Noise interference occurred
because of incorrect Encoder
Cable specifications.
Absolute
Encoder
Noise interference occurred
Position
because the Encoder Cable
Deviation
is too long.
Error (The
position
that was
saved in the
host con-
troller when
the power
Noise interference occurred
was turned
because the Encoder Cable
OFF is dif-
is damaged.
ferent from
the posi-
tion when
The Encoder Cable was
the power
subjected to excessive noise
was next
interference.
turned ON.)
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.
15.4 Troubleshooting Based on the Operation and Conditions of the Servomotor
Confirmation
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
Turn OFF the Servo Sys-
tem. Check the length of
the Encoder Cable.
Turn OFF the Servo Sys-
tem. Check the Encoder
Cable to see if it is
pinched or the sheath is
damaged.
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.
Turn OFF the Servo Sys-
tem. Check to see if the
machines are correctly
grounded.
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.
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.
Continued on next page.
Reference
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15
15-57