Rockwell Automation 1775-MX_S4A,D17756.3.1 User Manual PLC-3 BACKUP CONC(OR.DU1 - Manual (Page 100)

Programming Techniques
Chapter 5
5-19
When you select backup, you assign the same Data Highway or Data
Highway Plus station number to both the scanner module in the primary
processor and the one in the backup processor.
As long as the primary processor is controlling the outputs, the station
address of the Data Highway or Data Highway Plus channel in the backup
processor is modified. Table 5.E and Table 5.F show the station number
modifications for Data Highway and Data Highway Plus, respectively. At
switchover, the Data Highway or Data Highway Plus station number in the
backup processor assumes the station address assigned to it with the LIST
function.
Table 5.E
Data Highway Station Numbers for 1775ĆS5, ĆSR5 Modules
If the station address between:
The backup scanner module assumes a
station address that is:
000 and 276
8
100
8
higher than the assigned station number
300
8
and 376
8
100
8
lower than the assigned station number
Important: Never give the 1775-S5, -SR5 module the reserved station
address of 377
8
; and, when you select the backup operation, you cannot
give the module a station address of 277
8
.
Table 5.F
Data Highway Plus Station Numbers for 1775ĆS5, ĆSR5 Modules
If the station address between:
The backup scanner module assumes a
station address that is:
00 and 37
8
40
8
higher than the assigned station number
40
8
and 77
8
40
8
lower than the assigned station number