Mitsubishi MELSEC-A A2USHCPU-S1 User Manual page 165

10. MAINTENANCE AND INSPECTION
POINT
(1) Use the battery within the time shown by the guaranteed value of the battery
life.
(2) If the battery may be used exceeding the guaranteed time, perform ROM
operation to protect data in case that the battery will be exhausted during
power-off of the programmable controller. Or, after M9006 turns on, back up
data within the backup power time.
(3) When the battery (A6BAT) is not connected to the CPU module, its service
life is five years.
(4) When the battery-low special relay M9006 turns on, immediately change the
battery.
Even if an alarm has not yet occurred, it is recommended to replace the
battery periodically according to the operating condition.
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