10.2.2 Troubleshooting of Warnings
Refer to the following table to identity the cause of a warning and the action to be taken. Contact your
Yaskawa representative if the problem cannot be solved by the described corrective action.
Warning
Display
Warning Name
Situation at Warning
Occurrence
Cause Corrective Actions
A.900
Position Error
Pulse Overflow
Wiring of the servomo-
tor U, V, or W line is
incorrect.
Check the wiring of the cable for
motor main circuit.
Check whether there is any loose con-
nection in motor wiring or encoder
wiring.
The SERVOPACK gain
is too low.
Check the SERVOPACK gain.
Increase the servo gain by using the
function such as advanced autotuning.
The position reference
pulse frequency is too
high.
Lower the position reference pulse
frequency.
Lower the position reference pulse
frequency or the position reference
acceleration, or correct the electronic
gear ratio.
The position reference
acceleration is too high.
Lower the position reference accelera-
tion.
Apply a smoothing function, such as a
position reference acceleration/decel-
eration time constant (Pn216).
The excessive position
error alarm level
(Pn520) is too low for
the operating condi-
tions.
Check the excessive position error
alarm level (Pn520).
Set an appropriate value for the
Pn520.
A SERVOPACK fault
occurred.
−
Turn the power supply OFF and then
ON again. If the alarm still occurs, the
SERVOPACK may be faulty. Replace
the SERVOPACK.
A.901
Position Error
Pulse Overflow
Alarm at Servo
ON
When the /S_ON signal
was OFF, the servomo-
tor moved without
cleaning the counter for
position error pulses.
The number of position
error pulses exceeded
the maximum number
of pulses allowed.
−
Set Pn200.2 to 0 to clear the number
of position error pulses when the
/S_ON signal is OFF. Or set an appro-
priate value for the excessive position
error warning level at servo ON
(Pn528) when the /S_ON signal is
ON.
A.910
Overload:
Warning before
alarm A710 or
A720 occurs
The servomotor or
encoder wiring is incor-
rect or the connection is
faulty.
Check the wiring.
Correct the servomotor and encoder
wiring if they are wrong.
The servomotor is in
excess of the overload
protective characteris-
tics.
Check the overload characteristics of
the servomotor and reference input.
Reconsider the load and operation
conditions.
Or, check the servomotor capacity.
The servomotor is not
driven due to a mechan-
ical factor and the oper-
ating load has become
excessive.
Check the reference input and motor
speed.
Improve the mechanical factor.
A SERVOPACK fault
occurred.
−
The SERVOPACK may be faulty.
Replace the SERVOPACK.
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