User`s manual

Maintenance and inspection Battery life and replacement procedure
10 – 4
10.3.1 Battery life
Buffer battery for CPU
The battery life depends on the CPU type. From Q02CPU on, the battery life is also determined
by the CPU version (serial number). Refer to section 4.6 for checking the CPU serial number.
Extending the battery life with the universal model CPU
The universal model CPU has a pro-longing function to extend the battery life. When setting
"switch 3" of the intelligent function module switch setting on the tab "I/O assignment", to the
value 0001
H , only the internal clock is buffered by the battery. All other data, which are normally
buffered by the battery get lost during power shut off.
The current supplied by the battery for these CPU modules, what means the battery consump-
tion, is divided in four categories:
The following describes measures for reducing battery consumption:
– Enable the battery life-prolonging function.
– When storing a file register in standard the RAM, minimize the file register file.
– By performing the latch data backup function (to standard ROM).
If not powering on the programmable controller for a long period of time for shipment or other rea-
son, back up the data to the standard ROM.
NOTES
When the battery (Q6BAT) is not connected to the CPU module, its service life is five years.
Replace the battery after this time.
Do not use the battery exceeding the guaranteed value of the battery life.
If the battery life for data buffering has expired the guaranteed time of the following table,
– store program and data into a ROM, so that the data don’t get lost, if the PLC is powered
down or the battery voltage is low,
– during the time given in the right column of the following table, save program and data on
a PC, after special relay SM52 is set.
When the battery-low special relay SM52 turns on, immediately change the battery.
Factors of battery consumption
Battery consump-
tion category
Battery life-prolonging
function
Size of file register file in standard RAM (S
R
)
Set — 1
Not set No file registers or 0 k words < S
R
≤ 128 k words
2
128 k words < S
R
≤ 384 k words
3
384 k words < S
R
4
Tab. 10-5: Factors influencing the battery life time