Rockwell Automation 1791-XXXX Discrete I/O AC and DC Block I/O Input and Output Modules - Manual (Page 56)

Installing Block I/O
Chapter 3
3-37
Figure 3.26
Series Configurations for Block I/O Using the SLC Programmable
Controller
10834ĆI Install terminating resistor
on last block.
To 1747ĆSN
Scanner Module
1
2
15
16
Up to 16 blocks with
SLCĆ5/02 or SLCĆ5/03
If this is the last remote I/O adapter on the remote I/O link in a PLC
system, you must use a terminating resistor to terminate both ends of the
remote I/O link (scanner end and last block end). The size of the terminator
is determined by the system configuration.
Older system configurations must use a 150 ohm resistor at both ends.
With newer devices that can support it, you can use an 82 ohm termination
resistor at both ends. The 82 ohm terminators provide “extended node”
capability which allows you to have up to 32 physical devices on the
remote I/O link. (The number of logical racks capable of being addressed
by the scanner is not affected.)
ATTENTION: Devices that are operating at 230.4K baud must
have 82 ohm terminators in place for proper operation.
Extended Node Capability