Battery Life And Replacement Procedure - Mitsubishi Q01CPU User Manual

11
MAINTENANCE AND INSPECTION

11.3 Battery Life and Replacement Procedure

The batteries installed in the CPU module and SRAM card are used for data retention of
the program memory, standard RAM, and latch device 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 retained 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 or SRAM card is
lowered.
To identify the specific battery of the memory of which voltage is lowered, check the
contents of the special resisters SD51 and SD52.
SD51, SD52
For details of SD51 and SD52, refer to Section 12.8.
Power supply
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
POINT
The cases for memory retention by the CPU module battery and the SRAM card
battery are described below.
The important points are:
1) The CPU module battery cannot retain the SRAM card memory.
2) The SRAM card battery cannot retain the CPU module memory.
Table11.3 Cases for memory retention by the CPU module battery and the SRAM card battery.
Battery of CPU
Module Module
Connected
ON
Not connected
Connected
OFF
Not connected
b4 b3 b2 b1 b0
Battery error for CPU module
Battery alarm for SRAM card
Battery error for SRAM card
Diagram 11.1 Bit pattern
SRAM card Memory of CPU
battery
Installed
Not installed
Installed
Not installed
Installed
Not installed
Installed
Not installed
11.3 Battery Life and Replacement Procedure
When the battery
voltage is low, the
value is "1."
Memory of SRAM
Module Card
: Retained, : Not retained
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