Mitsubishi A1SJH(S8) User Manual page 148

10. MAINTENANCE AND INSPECTION
Yardsticks for preventive maintenance are as follows:
[1] Replace in 4 to 5 years even when the total power failure time is less than the
guaranteed value shown in the table above.
[2] Replace when the total power failure time exceeds the guaranteed value shown
in the table above and the M9006 is ON.
POINT
(1) See to it that a battery life does not exceed the guaranteed value.
(2) When the battery life exceeds the guaranteed value, perform ROM operation
to protect a program in case that the battery dies at programmable controller
power supply OFF, or back up a program and data after M9006 is turned on
(within power failure compensation time after an alarm occurrence)
(3) The battery (A6BAT) life which is disconnected to the CPU module is 5 years.
(4) Replace the battery soon after the special relay M 9006 is ON, which means
battery low.
However, replace a battery periodically even before the alarm appearance
according to the status of use.
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