
B–62835EN/01
8.TROUBLESHOOTING
325
920: Watch dog alarm or local RAM of servo has occurred
The timer used to monitor the operation of CPU is called the watch dog
timer. The CPU resets timer time every time a constant time has passed.
When an error occurs in CPU or peripheral device, timer is not reset but
the alarm is informed.
Refer to alarm 910 to 911. Local RAM or module has been checked.
In the Power Mate–D (A02B–0166–B001, –B520), the servo module
includes servo RAM, watch dog timer circuit, etc. Defectiveness of
hardware, abnormality or malfunctioning of detection circuit or the like
is considered. Therefore, replace servo module.
In the Power Mate–D (A02B–0166–B501, –B502, –B531) and Power
Mate–F the Base PCB includes servo RAM, watch dog timer circuit, etc.
Defectiveness of hardware, abnormality or malfunctioning of detection
circuit or the like is considered. Therefore, replace base PCB.
In the Power Mate, software may not workpiece properly due to failure
of memory. Change memory. (See Sec.8.31)
DC output voltage of power supply printed board may be faulty. Replace
the power supply printed board.
8.31
ALARM 920
(WATCH DOG OR
RAM PARITY)
points
D Watch dog timer alarm
D RAM parity error
Causes and Remedies
D Servo module is faulty
D Base printed board is
faulty
D Memory is faulty
D Power supply printed
board is faulty