User manual

111 Publication 1768-UM001C-EN-P - November 2007
Chapter 10
Maintain Nonvolatile Memory
Introduction
This chapter explains how to maintain nonvolatile memory.
CompactLogix controllers support the 1784-CF64 CompactFlash card for
nonvolatile memory. Nonvolatile memory lets you keep a copy of your project
on the controller. The controller does not need power to keep this copy.
You can load the copy from nonvolatile memory to the controller’s user
memory:
• each time you apply power.
• whenever there is no project in the controller and you apply power.
• at any time via RSLogix 5000 programming software.
No Battery is Required
The 1768 controller does not require a battery. When it is being shut down, the
controller uses internal flash memory to store its program. Energy stored in
the 1768 power supply maintains controller power long enough to store the
program to internal flash memory, not the external CompactFlash card.
Topic Page
No Battery is Required 111
Preventing a Major Fault During a Load 112
Using a CompactFlash Reader 112
Additional Resources 112
IMPORTANT
Nonvolatile memory stores the contents of the user memory
when you store the project.
• Changes made after storing a project are not reflected in
nonvolatile memory.
• If you change the project but do not store those changes, you
overwrite them when you load the project from nonvolatile
memory. If this occurs, you have to upload or download the
project to go online.
If you want to store changes such as online edits, tag values, or
a ControlNet network schedule, store the project again after
you make the changes.