Rockwell-automation 1794-L34 FlexLogix Controller System User Manual Manuel d'utilisateur télécharger pdf (Page 103)

103 Publication 1794-UM001G-EN-P - January 2007

Appendix

FlexLogix Back-Up on DeviceNet

Using This Appendix

This chapter offers a solution to back-up your FlexLogix controller on

DeviceNet. FlexLogix 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 FlexLogix 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 104

Power-Up and System Start-up 106

Developing the FlexLogix Back-Up Application 108

Using Indicators to Check Status 115

Development and Debugging Tips 115

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Rockwell-automation 1794-L34 FlexLogix Controller System User Manual Manuel d'utilisateur Page 103