Rockwell Automation T7150A Regent+Plus Communications Modules RS-232, RS-422 and RS-485 - Manual (Page 12)

Communications Modules (T7150A)
1 2
Industrial Control Services
Table 2. Communication Module Jumper Settings.
Note: n indicates jumper installed Point-to-
Point
Multidrop (Regent
R2 or Modbus)
Guarded Peer-
Link
Description Port 1 Port 2 End Middle End Middle
TX pair terminator E101 E201 n
RX pair terminator E102 E202 n n n
TX (-) pull-up E111 E211 n
RX (-) pull-up E112 E212 n n n
TX (+) pull-down E121 E221 n
RX (+) pull-down E122 E222 n n n
Transmit control E131 E231 n n n n
Transmit control E132 E232
Transmit control E133 E233 n n n n
Termination, Pull-up and Pull-down Resistor Jumpers
When the module is used for RS422 or RS485
communications, the jumper positions for the internal
termination, pull-up and pull-down resistors must be
considered. Each termination resistor connects an internal
120 Ohm resistor across a specific differential pair and the
pull-up and pull-down resistors connect a 1K Ohm resistor
between each signal line and +5V or Comm. These resistors
should be connected only at the end nodes of the multidrop
communication network. Nodes in the middle should not have
these jumpers connected.
Figure 7 identifies the signal lines, resistors and jumpers
associated with each port. Only the transmit (TX+ and TX-)
and receive (RX+ and RX-) signal pairs are shown. Other
jumpers and resistors for signal pairs CTS, RTS, DTR and
DSR are also located on the module but they are not used by
serial communications for the Regent and their jumper
positions are not important.
If desired, you can install the termination, pull-up and pull-
down resisters external to the communications module at the
ends of the multidrop network. In this case position the
jumpers in each communications module for a “middle”
Note: