2 Internal Memory in the CPU Unit
2-2
CP1E CPU Unit Software User’s Manual(W480)
2-1 Internal Memory in the CPU Unit
The internal memory in the CPU Unit consists of built-in RAM and built-in EEPROM. The built-in RAM is
used as execution memory and the built-in EEPROM is used as backup memory.
The built-in RAM is the execution memory for the CPU Unit.
The user programs, PLC Setup, and I/O memory are stored in the built-in RAM.
The data is unstable when the power is interrupted.
If a CP1W-BAT01 Battery (sold separately) is mounted to an N/NA-type CPU Unit, the data is backed
up by the Battery.
The user programs and parameters are backed up to the built-in EEPROM, so they are not lost.
The built-in EEPROM is the backup memory for user programs, PLC Setup, and Data Memory backed
up using control bits in the Auxiliary Area.
Data is retained even if the power supply is interrupted. Only the Data Memory Area words that have
been backed up using the Auxiliary Area control bits are backed up (Refer to 16-3 DM Backup Func-
tion). All data in all other words and areas is not backed up.
2-1-1 CPU Unit Memory Backup Structure
Built-in RAM
Built-in EEPROM
CPU Unit
Built-in EEPROM Built-in RAM
Backup memory
User Program Area
(Backup)
PLC Setup PLC Setup
DM Area DM Area
User Program Area
I/O Memory Areas
Data is retained even if the power
supply is interrupted for longer
than the backup time of the built-in
capacitor.
Execution Memory
Automatic backup
Read at startup
Automatic backup
Read at startup
Backup using bit in Auxiliary Area
DM Area data read at startup
If a CP1W-BAT01 Battery (sold
separately) is mounted to an N/NA-type
CPU Unit, which is normally backed up
by a built-in capacitor, data will be
backed up by the battery.
Area where data is backed up
even if the power supply is
interrupted for longer than the
back-up time of the built-in
capacitor. *
Area where data is cleared if
the power supply is
interrupted for longer than the
back-up time of the built-in
capacitor. *
* E-type CPU Units: 50 hours at 25,
N/NA-type CPU Units: 40 hours at 25
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