Rockwell Automation T7150A Regent+Plus Communications Modules RS-232, RS-422 and RS-485 - Manual (Page 11)

Communications Modules (T7150A)
P D - 7 0 0 2 M a r - 0 6
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Net Master/Net Slave
Used by the Regent for Guarded Peer-Link communications to
other multidrop Regents. These ports require a node number.
Modbus
Supports connection to external Modbus communications
equipment that acts as a Modbus Master (the Regent is a
Modbus Slave). A Modbus port supports the Modbus RTU
protocol. Modbus ports can be used in point-to-point or
multidrop configurations. These ports require a node number.
Jumper Settings for Point-to-Point and
Multidrop Communications
Each port can be independently configured for point-to-point
or multidrop connections. When shipped from the factory,
jumpers on-board the communications module are set for
point-to-point communications. These settings are
appropriate when a single Regent is connected to a PC or
other communications equipment. The port definition can be
COMM, ASCII or Modbus (point-to-point) as described above.
When the port definition is Multidrop, Net Master, Net Slave
or Modbus (multidrop) then the jumper settings on the
module must be changed.
Changing Jumper Settings
The jumper settings on the module are used to determine how
the transmit lines of the serial ports are controlled and also
determine if internal termination, pull-up and pull-down
resistors are connected to the serial lines. Table 2 shows the
proper jumper settings for point-to-point, multidrop (Regent
R2 or Modbus) and Guarded Peer-Link communications.