Rockwell Automation 1775-KA PLC-3 Communication Adapter Module User Manual - Manual (Page 41)

Installation
Chapter 2
2Ć29
2. Use the LIST function to disable the modem and Data Highway
ports.
3. Use the LIST function to select BACKUP OPERATION for both the
primary and backup 1775–KA modules. For more information, see
the PLC–3 Installation and Operation manual (publication
1775–6.7.1). Thus, when you select BACKUP OPERATION, the
condition appears like this:
5*BACKUP OPERATION
4. Use the LIST function to assign the same station address to the
modules for the primary PLC–3 and the backup PLC–3 processor.
You can never give the 1775–KA module a station address of 3778,
and when you select the BACKUP OPERATION, you can not give
the module an address of 2778.
Because you have chosen BACKUP OPERATION, the module in the
backup PLC–3 will assume an address other than the address you
assign it with the LIST function (Figure 2.12).
You assign both modules an identical address.
If the address
is between:
The backup module assumes
an address that is:
001
8
and 276
8
100
8
higher than the primary module
300
8
and 376
8
200
8
lower than the primary module
At switchover, the address for the backup module returns to the
station address you assigned to it with the LIST function.
5. Use the LIST function to enable whichever (Data Highway or
Modem) port you are using to connect primary to backup.