Rockwell Automation 1761 MicroLogix 1000 Programmable Controllers - Manual (Page 83)

Programming Overview
4–7
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When the processor file is downloaded to the micro controller, it is first stored in the
volatile RAM. It is then transferred to the non-volatile EEPROM, where it is stored
as both backup data and retentive data.
CPU
EEPROM
Backup Data
Retentive Data
Program Files
RAM
CPU Workspace
Retentive Data
Program Files
Programming Device
Note If you want to ensure that the backup data is the same for every micro controller you
are using, save the program to disk before downloading it to a micro controller.
Normal Operation
During normal operation, both the micro controller and your programming device
can access the processor files stored in the RAM. Any changes to retentive data that
occur due to program execution or programming commands affect only the retentive
data in the RAM.
The program files are never modified during normal operation. However, both the
CPU and your programming device can read the program files stored in RAM.
CPU
RAM
CPU Workspace
Retentive Data
Program Files
EEPROM
Backup Data
Retentive Data
Program Files
Programming Device
Programming