Emerson Network Router User Manual page 21

Installation and Setup
Figure 2-7 Modbus/RS-485 connection to transmitter or multidrop network
DCS or
PLC
Notes:
• Connect the interface leads to the RS-485 terminals on the transmitter, or to any point on the network.
• Ensure that no other Modbus master devices are currently active on the network.
• For RFT9712 transmitters, set the jumper for RS-485 communications.
• For long-distance communication, or if noise from an external source interferes with the signal, add two 120-Ω
terminating resistors (R1) at each end of the RS-485 network.
Installation and Use Manual
R1
Attach serial port or USB
adapter if necessary (not
shown)
RS-485 terminals
Transmitter
RS-232 <-> 2-wire RS-485
interface converter
15