YASKAWA JUSP-MD D01A Series User Manual page 318

Problem Probable Cause
Overtravel (OT)
Incorrect servomotor stop method
(Continued from
selection
previous page.)
Improper limit switch position and
Improper Stop
dog length
Position by
The overtravel limit switch position
Overtravel (OT)
is too short for the coasting
Signal
distance.
Noise interference due to incorrect
encoder cable specifications
Noise interference due to length of
encoder cable.
Noise influence due to damaged
encoder cable.
Excessive noise to encoder cable.
The FG potential varies because of
influence from machines on the ser-
vomotor side such as the welder.
SERVOPACK pulse count error due
to noise
Excessive vibration and shock to
Position Error
the encoder
(Without Alarm)
Unsecured coupling between
machine and servomotor
Noise interference due to improper
I/O signal cable specifications
If the reference pulse input multipli-
cation switching function is being
used, noise may be causing the I/O
signals (/PSEL and /PSELA) used
for this function to be falsely
detected.
Noise interference due to length of
I/O signal cable
An encoder fault occurred. (The
pulse count does not change.)
A fault occurred in the multi-wind-
ing drive unit.
9.3 Troubleshooting Malfunction Based on Operation and Conditions of the Servomotor
Investigative Actions
Check the settings for parameters
Pn001.0 and Pn001.1 when the ser-
vomotor power is OFF.
Check the settings for parameters
Pn001.0 and Pn001.1 when in
torque control.
−
−
The encoder cable must be tinned
annealed copper shielded twisted-
pair or screened unshielded twisted-
pair cable with a core of 0.12 mm
min.
Check the length of the encoder
cable.
Check if the encoder cable is bent
and the sheath is damaged.
Check if the encoder cable is bun-
dled with a high-current line or near
a high-current line.
Check if the machines are correctly
grounded.
Check if the I/O signal line from the
encoder is influenced by noise.
Check if vibration from the machine
occurred or servomotor installation
is incorrect (mounting surface accu-
racy, fixing, alignment, etc.).
Check if a position error occurs at
the coupling between machine and
servomotor.
The I/O signal cable must be tinned
annealed copper shielded twisted-
pair or screened unshielded twisted-
pair cable with a core of 0.12 mm
min.
The I/O signal cable must be tinned
annealed copper shielded twisted-
pair or screened unshielded twisted-
pair cable with a core of 0.12 mm
min.
Check the I/O signal cable length.
−
−
Corrective Actions
Select a servomotor stop method
other than "coast to stop."
Select a servomotor stop method
other than "coast to stop."
Install the limit switch at the
appropriate position.
Install the overtravel limit switch at
the appropriate position.
Use the specified encoder cable.
2
The encoder cable must be no more
than 50 m.
Replace the encoder cable and mod-
ify the cable layout.
• Change the cable layout so that
no surge is applied.
• Use a double-shielded encoder
cable.
Properly ground the machines
encoder FG.
Take measures against noise in the
encoder wiring.
Reduce the machine vibration or
mount the servomotor securely.
Secure the coupling between the
machine and servomotor.
Use input signal cable with the
specified specifications.
2
Use input signal cable that satisfy
specifications.
2
The I/O signal cable length must be
no more than 3 m.
Replace the servomotor.
Replace the multi-winding drive
unit.
(cont'd)
9
9-29