3.1 FT82 SERVOPACKs with Analog Voltage/Pulse Train References
3.1.7 Troubleshooting Based on the Operation and Conditions of the Servomotor
3-48
Position
Deviation
(without
Alarm)
The Encoder Cable was sub-
jected to excessive noise
interference.
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 wiring
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.
–
The coupling between the
machine and Servomotor is
not suitable.
Check to see if position
offset occurs at the cou-
pling between machine
and Servomotor.
Correctly secure the
coupling between the
machine and Servomo-
tor.
–
Noise interference occurred
because of incorrect I/O sig-
nal cable specifications.
Check the I/O signal
cables to see if they sat-
isfy specifications. 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.
–
If reference pulse input multi-
plication switching is being
used, noise may be causing
the I/O signals used for this
function (/PSEL and /PSELA)
to be falsely detected.
Check the I/O signal
cables to see if they sat-
isfy specifications. 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 an I/O signal cable
is too long.
Check the lengths of the
I/O signal cables.
The I/O signal cables
must be no longer than
3 m.
–
An encoder fault occurred.
(The pulse count does not
change.)
–
Replace the Servomo-
tor.
–
A failure occurred in the SER-
VOPACK.
–
Replace the SERVO-
PACK.
–
Continued on next page.
Continued from previous page.
Problem
Possible Cause
Confirmation
Correction
Reference
