Rockwell Automation 1775-S5_SR5,D17756.5.5 User Manual PLC-3 FAMILY I/0 - Manual (Page 39)

Configuring the Scanner through LIST
Chapter 2
2-13
4 - Backup Operation
Select the Backup Operation option from the configuration screen to
configure the DH and DH+ station numbers when backed up. See
Table 2.A.
Table 2.A
Backup Operation Options
If backup is: The DH and DH+ station number of the backup scanner module:
Selected is automatically modified before and after switchover. This allows you to
have identical configurations in both the primary and the backup
processor.
Not selected remains the same both before and after switchover. The primary and
backup processors must have unique station numbers.
Regardless of which mode you select, both the primary and the backup DH
and DH+ channels are active. There is no selection for the backup DH or
DH+ channel to remain silent on the link until switchover.
When you select backup operation, you assign the same DH or DH+
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 DH or DH+ channel in the backup processor is modified.
Table 2.B and Table 2.C show the station number modifications for DH
and DH+, respectively. At switchover, the DH or DH+ station number in
the backup processor assumes the station address assigned to it with the
LIST function.
Table 2.B
DH 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: Do not 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
.