Battery Life And Replacement Procedure - Mitsubishi Electric QS001CPU User Manual

11
MAINTENANCE AND INSPECTION

11.3 Battery Life and Replacement Procedure

The battery installed in the safety CPU module is used for data retention of the program
memory and operation/error history during the power failure. Special relays SM51 and
SM52 turn on due to the decrease of battery voltage. Even if the special relays turn on, the
program and operation/error data are not erased immediately.
After relay SM51 turns on, replace the battery quickly within the data retention time for
power failure (3 minutes).
SM51 and SM52 turn on when the battery voltage of the CPU module is lowered.
The battery voltage drop can be checked with the contents of the special registers SD51
and SD52.
SD51, SD52
For details of SD51 and SD52, refer to Section 12.7.
POINT
SM51 turns on when the battery voltage falls below the specified value, and
remains ON even after the voltage is recovered to the normal value.
SM52 turns on when the battery voltage falls below the specified value, and turns
OFF when the voltage is recovered to the normal value.
After SM51 and/or SM52 turns on, replace the battery quickly.
b15 to
Fixed at 0
b1 b0
Error of a CPU
module battery
Figure 11.1 Bit pattern
11.3 Battery Life and Replacement Procedure
When the battery
voltage is low, the
value is "1."
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9
10
11
12
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