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Replacing User-serviceable Parts Section 11-2
data area and other data are not correct for the user program, unexpected
accidents may occur.
11-2 Replacing User-serviceable Parts
The following parts should be replaced periodically as preventative mainte-
nance. The procedures for replacing these parts are described later in this
section.
• Battery (backup for the CPU Unit’s internal clock and RAM)
Battery Functions The battery maintains the internal clock and the following data of the CPU
Unit’s RAM while the main power supply is OFF.
• Retained regions of I/O memory (such as the Holding Area and DM Area)
If the battery is not installed or battery voltage drops too low, the internal clock
will stop and the data in RAM will be lost when the main power supply goes
OFF.
Battery Service Life and
Replacement Period
At 25°C, the maximum service life for batteries is five years whether or not
power is supplied to the CPU Unit while the battery is installed. The battery’s
lifetime will be shorter when it is used at higher temperatures.
The following table shows the approximate minimum lifetimes and typical life-
times for the backup battery (total time with power not supplied).
Note The minimum lifetime is the memory backup time at an ambient temperature
of 55°C. The typical lifetime is the memory backup time at an ambient temper-
ature of 25°C.
Model Approx.
maximum lifetime
Approx. minimum
lifetime (See note.)
Typical lifetime
(See note.)
CP1L-M@@D@-D
CP1L-L@@D@-D
5 years 13,000 hours
(approx. 1.5 years)
43,000 hours
(approx. 5 years)
Memory Backup Time
Ambient temperature
This graphic is for reference only.
5 yr
4 yr
3 yr
2 yr
1 yr
CP1L CPU Unit
25°C
40°C
55°C
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