Rockwell Automation 1775-MX_S4A,D17756.3.1 User Manual PLC-3 BACKUP CONC(OR.DU1 - Manual (Page 48)

Chapter
4
4-1
Using the 1775ĆMX
Memory Communication Module
This chapter describes how to use 1775-MX memory communication
modules. Depending on your application, you can program the memory
communication module to:
transfer data from the primary processor to the backup processor to
ensure that the data table in the backup processor matches that in the
primary processor.
transfer data from the backup processor to the primary processor to
provide data or status back to the primary.
download memory from the primary processor to the backup processor
to initialize the backup processor with the same data and configuration
as the primary processor.
control on-line editing capability to prevent the primary processor or
backup processor from being programmed independently.
compare the ladder programs in the primary and backup processors to
ensure that all or part of the programs are identical.
voluntarily transfer control to the backup processor. For example, you
could switch over to the backup processor when performing
maintenance on the primary processor.
disable the backup processor from assuming control of the outputs after
switchover. For example, when on-line editing is occurring in the
primary processor but the changes have not yet been sent to the backup
processor.
Chapter Objectives