
8. TROUBLESHOOTING
B–64115EN/01
484
A watchdog error or RAM parity error occurred in the circuit on an axis
control card.
Alarm 920 indicates that either of the above errors occurred in the control
circuit for axes 1 to 4.
The optical cable, axis control cards, CPU card, or motherboard may be
defective.
The servo control circuit monitors the operation of the main CPU. If a
fault occurs in the CPU or its peripheral circuit, so that the watchdog timer
is not reset, a watchdog error occurs.
Replace the optical cable. A defective optical cable may cause this
problem.
Replace the axis control cards.
Replace the CPU card.
If any of the above actions does not solve the problem, replace the main
board.
Axis control
card
CPU card
8.27
ALARM 920
(SERVO ALARMS)
Causes and actions
D Watchdog error
D Replacing the optical
cable
D Replacing the axis
control cards
D Replacing the CPU card
D Replacing the main
board
D Installation position of
each card