Rockwell Automation 150 USE MN/SMC DIALOG + CONTROLLER - Manual (Page 70)

4-6 Programming
Parameter Management Before you begin programming, it’s important to understand how the
controller memory is:
• structured within the SMC Dialog Plus controller
• used on power-up and during normal operation
Refer to Figure 4.2 and the explanations below.
Figure 4.2 Memory Block Diagram
Random Access Memory (RAM)
This is the work area of the controller after it is powered up. When
you modify parameters in the Program mode, the new values are
stored in RAM. When power is applied to the controller, parameter
values stored in the EEPROM are copied to RAM. RAM is volatile
and the values stored in this area are lost when the controller is
powered down.
Read-only Memory (ROM)
The SMC Dialog Plus controller comes with factory default
parameter values. These settings are stored in nonvolatile ROM and
are displayed the first time you enter the Program mode.
Electrically Erasable Programmable Read-only Memory
(EEPROM)
The SMC Dialog Plus controller provides a nonvolatile area for
storing user-modified parameter values in the EEPROM.
EEPROM RAM ROM