Rockwell Automation 1791-IOBB USER MANUAL - Manual (Page 18)

Installing Block I/O
Chapter 2
2Ć9
Termination Resistor
A termination resistor must be installed on the last block in a series.
Connect the resistor as shown in Figure 2.8. Use the resistor as identified
in Table 2.D.
Figure 2.8
Installing the Termination Resistor
Tighten screw to clamp
wires and termination resistor.
Termination Resistor
Connect termination
resistor across terminals
1 and 2
10835-I
Table 2.D
Terminator Requirements
System Terminator Resistor
PLC-2, PLC-3, PLC-5 family,
SLC 500 family
150 ohm - 57.6K and 115.2K baud
82 ohm - 230.4K baud
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 configurations can 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