Rockwell Automation 5720 DriveLogix System - Manual (Page 225)

1 Publication 20D-UM002C-EN-P - November 2003
Chapter
12
DriveLogix Back-Up on DeviceNet
Using This Chapter
This chapter offers a solution to back-up your DriveLogix controller on
DeviceNet. DriveLogix Back-Up on DeviceNet is a simple, low-cost, back-up
system most effective when used in smaller applications that require fast
switchovers from a primary to a secondary controller.
This back-up solution will:
• minimize downtime in case of controller failure when the same program
is used in both programs.
• mitigate the risk of changes adversely affecting the application (use old,
proven program in one controller and new, untested program in other
controller). If the new untested program causes a problem, a forced
switchover can be made to the older proven program without
downloading the program again.
The DriveLogix Back-Up on DeviceNet solution takes advantage of Shared
DeviceNet Mastership of Slave I/O Devices technology. Typically, only a single
DeviceNet master exists for any particular slave. With Shared DeviceNet
Mastership, two masters can exist. Heartbeat communications between
primary and secondary controllers determines which scanner is the master and
which scanner remains in stand-by mode.
For information about: See page
How the Back-up Works 12-2
Power-Up and System Start-up 12-4
Developing the DriveLogix Back-Up Application 12-6
Using Indicators to Check Status 12-13
Development and Debugging Tips 12-13