Rockwell Automation 1775-MX_S4A,D17756.3.1 User Manual PLC-3 BACKUP CONC(OR.DU1 - Manual (Page 49)

Using the 1775ĆMX
Memory Communication Module
Chapter 4
4-2
As shown in Table 4.A, you can control operation of memory
communication modules by using:
LIST functions (see page 4-3).
message (MSG) instructions (see page 4-16).
Typically, you use LIST functions during the development of your
application. This approach lets you select and deselect options manually.
In addition to providing additional selections, you can use message
instructions to automate memory communication module setup once you
are sure of the application. By inserting message instructions into the
ladder program, the memory communication module can be configured
automatically when powering up in the run mode or whenever the system
changes from program mode to run mode.
Table 4.A
LIST Functions and MSG Instructions
By Using:
You can: LIST Function MSG Instruction
transfer the contents of the data table from the
primary to the backup processor continuously
Yes Yes
transfer the contents of selected files from the
primary to the backup processor continuously
Yes Yes
transfer the contents of the data table from the
primary to the backup processor one time
No Yes
transfer the contents of selected files from the
primary to the backup processor one time
No Yes
stop further continuous transfers once the transfer
in progress completes
Yes Yes
download memory from the primary to the backup
processor
Yes Yes
control onĆline editing capability for a
programmable terminal
Yes Yes
compare the ladder program in the backup
processor with the one in the primary processor
continuously
Yes Yes
transfer control to the backup processor No Yes
inhibit the backup processor from taking control of
outputs when the primary processor faults
No Yes
transfer backup processor data to the primary
processor
Yes Yes
Controlling the Operation
of Memory Communication
Modules