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Replacing User-serviceable Parts Section 12-2
tings. If data area and other data are not correct for the user program, un-
expected accidents may occur. Be sure to include the routing tables,
Controller Link Unit data link tables, network parameters, and other CPU
Bus Unit data, which are stored as parameters in the CPU Unit. Refer to
the CPU Bus Unit and Special I/O Unit operation manuals for details on the
data required by each Unit.
2. The simple backup operation can be used to store the user program and
all parameters for the CJ1-H CPU Unit, DeviceNet Units, Serial Communi-
cations Units, and other specific Units in a Memory Card as backup files.
A Memory Card and the simple backup operation can be used to easily re-
store data after replacing any of these Units. Refer to the CS/CJ Series
Programming Manual (W394) for details.
12-2 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
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 and when power
is not supplied to the CPU Unit for long periods.
The following table shows the approximate minimum lifetimes and typical life-
times for the backup battery (total time with power not supplied).
Model Approx.
maximum
lifetime
Approx. minimum
lifetime
(See note.)
Typical lifetime
(See note.)
CJ1H-CPU@@H-R 5 years 6,500 hours (0.75 years) 43,000 hours (5 years)
CJ1@-CPU@@H 5 years 6,500 hours (0.75 years) 43,000 hours (5 years)
CJ1G-CPU@@ 5 years 6,500 hours (0.75 years) 43,000 hours (5 years)
CJ1M-CPU@@ 5 years 13,000 hours (1.5 years) 43,000 hours (5 years)
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