Mitsubishi Electric MELSERVO-JN Series - Page 21

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Introduction
№ Step of occurrence Fault Investigation Possible cause Reference
3 Input command
pulse.
(Test operation)
(In the position
control mode)
Servo motor rotates in
reverse direction.
Check the cumulative command
pulses on the status display or on
MR Configurator.
1. Mistake in wiring to controller.
2. Mistake in setting of parameter
No. PA14.
Section
4.1.12
Section
5.3
Check the set value of parameter
No.PA14 (rotation direction
selection).
4 Switch on forward
rotation start (ST1)
or reverse rotation
start (ST2).
(In the internal
speed control
mode)
Servo motor does not
rotate.
Check the ON/OFF status of the
input signal on the external I/O
signal display (refer to section
5.8).
LSP, LSN, ST1 or ST2 is off. Section
5.8
Check the internal speed
commands 0 to 7 (parameters No.
PC05 to PC08 and PC31 to
PC34).
Set value is 0. Section
4.3.2
Check the forward torque limit
(parameter No. PA11) or reverse
torque limit (parameter No. PA12).
Torque limit level is too low as
compared to the load torque.
Section
4.1.10
5 Switch on forward
rotation selection
(RS1) or reverse
rotation selection
(RS2).
(In the internal
torque control
mode)
Servo motor does not
rotate.
Check the set value of parameter
No.PC12 (internal torque
command).
Internal torque command is too
low as compared to the load
torque.
Section
4.3.2
Check the ON/OFF status of the
input signal on the external I/O
signal display (refer to section
5.8).
RS1 or RS2 is off. Section
5.8
Check the internal speed limits 0
to 7 (parameters No. PC05 to
PC08 and PC31 to PC34).
Set value is 0. Section
4.3.2
Check the forward torque limit
(parameter No. PA11) or reverse
torque limit (parameter No. PA12).
Set value is 0. Section
4.1.10
6 Switch on forward
rotation start (ST1)
or reverse rotation
start (ST2).
(In the positioning
mode)
Servo motor does not
rotate.
Check the ON/OFF status of the
input signal on the external I/O
signal display (refer to section
5.8).
LSP, LSN, ST1 or ST2 is off. Section
5.8
Check the values of position data
and servo motor speed set in the
point table or program.
Set value is 0. Chapter
13
Check the forward torque limit
(parameter No. PA11) or reverse
torque limit (parameter No. PA12).
Torque limit level is too low as
compared to the load torque.
Section
4.1.10
7 Gain adjustment
(In the position
control mode)
(In the internal
speed control
mode)
(In the positioning
mode)
Rotation ripples (speed
fluctuations) are large at
low speed.
Make gain adjustment in the
following procedure.
1. Increase the auto tuning
response level.
2. Repeat acceleration and
deceleration several times to
complete auto tuning.
Gain adjustment fault Chapter 6
Large load inertia
moment causes the
servo motor shaft to
oscillate side to side.
If the servo motor may be run with
safety, repeat acceleration and
deceleration several times to
complete auto tuning.
Gain adjustment fault Chapter 6
8 Cyclic operation
(In the position
control mode)
Position shift occurs. Confirm the cumulative command
pulses, the cumulative feedback
pulses and the actual servo motor
position.
Pulse counting error, etc. due to
noise.
(2) in this
section