Rockwell Automation 1791-I0VX BLOCK I/O - Manual (Page 26)

Installing Block I/O
Chapter 2
2-14
Termination Resistor
A termination resistor must be used on the last block in the series. A 150
ohm and 82 ohm termination resistors are built into the unit. To select the
termination resistor, position the switch to the desired position as shown in
Figure 2.5.
Figure 2.5
Installing the Termination Resistor
Position switch to connect termination resistor
across 1 and 2 as follows:
150 ohm - position switch at top;
82 ohm - position switch at bottom;
OFF - no resistor - position switch in middle.
2
(CLR)
Shield
1
(BLU)
24VDC
24VDC
RET
Chassis
GND
10930-I
- 150 OHM
- 82 OHM
-OFF
TERMINATION
RESISTOR
If this is the last remote I/O adapter on the RIO 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 RIO 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