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Replacing User-serviceable Parts Section 12-2
Note 1. When replacing a CPU Unit, be sure that not only the user program but
also all other data required for operation is transferred to or set in the new
CPU Unit before starting operation, including DM Area and HR Area set-
tings. If data area and other data are not correct for the user program, un-
expected accidents may occur.
2. 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 pa-
rameters 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.
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 in the retained
regions of I/O memory while the main power supply is OFF.
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.)
CP1H-X/XA40DR-A
CP1H-X/XA40DT(1)-D
CP1H-Y20DR-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
CP1H CPU Unit
25°C
40°C
55°C
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