Mitsubishi Q170MCPU, User Manual

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6 INSPECTION AND MAINTENANCE
6.5 Battery
The battery installed in the Motion controller is used for data retention during the
power failure of the program memory and latch device.
The data stored in the RAM built-in Motion controller are shown below.
• PLC CPU area : Clock data, Latch devices (L), Devices of latch range, Error history
and Data in standard RAM
• Motion CPU area : Programs, Parameters, Motion devices (#), Devices of latch
range, and Absolute position data
Special relays (SM51, SM52, SM58 or SM59) turn on due to the decrease of battery
voltage. Even if the special relays turn on, the program and retained data are not
erased immediately.
However, if these relays are overlooked, the contents may be erased.
After relay SM51 or SM58 turns on, replace the battery quickly within the data
retention time for power failure (3 minutes).
POINT
(1) SM51 or SM58 turns on when the battery voltage falls below the specified
value, and remains ON even after the battery voltage is recovered to the
normal value. SM51 or SM58 turns off by power supply on again or reset.
(2) After SM51, SM52, SM58 or SM59 turns on, replace the battery quickly.
• SM51 or SM52 turns on at the battery voltage 2.5V or less.
• SM58 or SM59 turns on at the battery voltage 2.7V or less.
(3) If SM51 turns on, the details for the data of RAM built-in Motion controller
cannot be guaranteed.
It is recommended to back-up the data periodically.