3.1 FT82 SERVOPACKs with Analog Voltage/Pulse Train References
3.1.7 Troubleshooting Based on the Operation and Conditions of the Servomotor
3-46
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.
Check the Encoder Cable
to see if it satisfies speci-
fications. 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.
Check the length of the
Encoder Cable.
The Encoder Cable
length must be 50 m
max.
–
Noise interference occurred
because the Encoder Cable
is damaged.
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.
–
Replace the Encoder Cable
and correct the cable instal-
lation environment.
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.
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.
Check to see if there is
noise interference on the
I/O signal line from the
encoder or Serial Con-
verter Unit.
Implement counter-
measures against noise
for the encoder or
Serial Converter Unit
wiring.
–
The encoder was subjected
to excessive vibration or
shock.
Check to see if vibration
from the machine
occurred.
Check the Servomotor
installation (mounting sur-
face precision, securing
state, and alignment).
Reduce machine vibra-
tion. Or, improve the
mounting conditions of
the Servomotor.
–
A failure occurred in the
encoder.
–
Replace the Servomo-
tor.
–
A failure occurred in the SER-
VOPACK.
–
Replace the SERVO-
PACK.
–
Host Controller Multiturn
Data or Absolute Encoder
Position Data Reading Error
Check the error detec-
tion section of the host
controller.
Correct the error detec-
tion section of the host
controller.
–
Check to see if the host
controller is executing
data parity checks.
Perform parity checks
for the multiturn data or
absolute encoder posi-
tion data.
–
Check for noise interfer-
ence in the cable
between the SERVO-
PACK and the host con-
troller.
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.
Continued from previous page.
Problem
Possible Cause
Confirmation
Correction
Reference