YASKAWA SGD7S series Product Manual page 537

Problem Possible Cause
Noise interference occurred
because the Encoder Cable
is too long.
Noise interference occurred
because the Encoder Cable
is damaged.
The Encoder Cable was sub-
ject to excessive noise inter-
ference.
Absolute
Encoder
There is variation in the FG
Position potential because of the
influence of machines on the
Deviation
Servomotor side, such as a
Error (The
welder.
position
that was
There is a SERVOPACK
saved in the
pulse counting error due to
host con-
noise.
troller when
the power
was turned
OFF is dif-
ferent from
the posi-
The encoder was subjected
tion when
to excessive vibration or
the power
shock.
was next
turned ON.)
A failure occurred in the
encoder.
A failure occurred in the
SERVOPACK.
Host Controller Multiturn
Data or Absolute Encoder
Position Data Reading Error
12.4 Troubleshooting Based on the Operation and Conditions of the Servomotor
Confirmation
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).
–
–
Check the error detec-
tion section of the host
controller.
Check to see if the host
controller is executing
data parity checks.
Check for noise interfer-
ence in the cable
between the SERVO-
PACK and the host con-
troller.
Continued from previous page.
Correction Reference
• 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.
Correct the error detec-
tion section of the host
–
controller.
Perform parity checks
for the multiturn data or
–
absolute encoder posi-
tion data.
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.
12
12-61