Rockwell Automation 1775-MX_S4A,D17756.3.1 User Manual PLC-3 BACKUP CONC(OR.DU1 - Manual (Page 35)

Installing a Backup System
Chapter 2
2-20
8. If the last scanner is a 1775-S4A or 1775-SR scanner module, install
a 1770-XT terminator to the I/O channel 1 terminals as shown in
Figure 2.15. For 1775-S5 and 1775-SR5 scanner modules, you can
either install a 1770-XT terminator or select a terminator by using the
internal switches as shown in Figure 2.17 on page 2-23.
9. Using the LIST function, configure I/O channel 1 in the backup
processor for peer-to-peer communication. Use the same peer-to-peer
station number as the primary processor. If the primary processor is a
master, configure the backup processor as a master. If the primary
processor is a slave, configure the backup processor as a slave.
Important: The master number must be different from all slave numbers
on the link. The master number and all slave numbers must be unique and
selected from numbers 81 through 89.
As shown in the above procedure, the twinaxial cable shield is always
connected on 1775-S5 or 1775-SR5 scanner modules but alternately
connected between 1775-S4A or 1775-SR scanner modules.