Rockwell Automation 1775-S5_SR5,D17756.5.5 User Manual PLC-3 FAMILY I/0 - Manual (Page 57)

I/O Communication
Chapter 3
3-9
Figure 3.7 shows example rungs using the run/backup bit (S000:3/17). To
use these rungs for backup communication, you must enter them into the
primary and backup systems. The run/backup bit is set in the primary
system and reset in the backup system. The counter is updated only in the
backup system.
In this example, both the primary and backup systems use input file 1 as
the input file and output file 1 as the output file for the backup
communication channel. For detailed information on the backup feature,
refer to the PLC-3 Family Controller Backup Concepts Manual
(publication 1775-6.3.1).
Figure 3.7
Example Rungs for a Backup Communication Channel
17
MOVE FROM A TO R
A : WCACC:0001
25
R : W0001:0007
0000000000011001
MOV
S0003
17
MOVE FROM A TO R
A : WI001:0007
25
R : WCACC:0001
MOV
S0003
0000000000011001