
No. LED display Description Countermeasure
251
Input data 2 is invalid. Check input data 2, specified with a function
code.
254
A function code or mode is invalid. Check the command code, specified with a
function code. Check the mode.
255
Operation cannot be activated because an
invalid mode is specified or because block
execution is in progress.
Check the mode. Check whether a block is
being executed.
290
The interface switch signal (DRC) was
switched during block execution.
Switch the signal after block execution stops.
291
The speed of an axial movement specified by
an external pulse has exceeded the upper
limit. This occurs only when the EPEXA bit of
parameter No.001 is set to 1.
Check the speed specified by the external
pulse. Check the magnification of the external
pulse (parameters No.062 and 063).
292
A checksum error for the non-volatile memory
was detected.
Parameters are cleared. Set the parameters
again. If this alarm subsequently recurs,
replace the unit.
P
ulse coder alarms
No. LED display Description Countermeasure
300
A communication error (DTER) for the serial
pulse coder was detected.
Check the connection of the signal cable. If the
cable is normal, the pulse coder may be
defective. Turn the power off. If the alarm
recurs when the power is reapplied, replace
the serial pulse coder, together with the motor.
301
A communication error (CRCER) for the serial
pulse coder was detected.
Check the connection of the signal cable. If the
cable is normal, the pulse coder or servo
amplifier unit may be defective. This error can
also be caused by external noise.
302
A communication error (STBER) for the serial
pulse coder was detected.
Check the connection of the signal cable. If the
cable is normal, the pulse coder or servo
amplifier unit may be defective. This error can
also be caused by external noise.
303
An LED disconnection (LDAL) was detected in
the serial pulse coder.
Turn the power off. If this alarm recurs when
the power is reapplied, replace the motor.
304
A mispulse alarm (PMAL) for the serial pulse
coder was detected.
Turn the power off. If this alarm recurs when
the power is reapplied, replace the motor.
305
A miscount alarm (CMAL) for the serial pulse
coder was detected.
Turn the power off. If the alarm recurs when
the power is reapplied, replace the motor.
If the alarm does not recur, restart the
operation from reference position return.
306
The motor has overheated (OHAL). This alarm is issued when the motor has
overheated, causing the thermostat to trip.
Possible causes include an excessively high
ambient temperature and excessively strict
operating conditions. Check the actual cause.
If it occurs again when the motor is cooled, the
motor or servo amplifier may have failed.
Replace the faulty motor or servo amplifier.
EDIT
DATE DISIGNE
DESCRIPTION
TITLE
DRAW
ALARM FOR FANUC SERVO MOTOR β series I/O Link OPTION (FANUC Series
16i/18i/21i/20i/160i/180i/210i– MODEL A MAINTENANCE MANUAL),(FANUC Series
16i/160i/160is/18i/180i/180is/21i/210i/210is – MODEL B MAINTENANCE MANUAL)
B-63005EN/02-2, B-63525EN/02-1
SHEET
3/8
APPROV.
FANUC LTD