Connecting A Serial Port To Multiple Rosemount 4088B Transmitter (Multi-Drop) (3Srsg4) - Emerson FB3000 Instruction Manual

2.11.6 Connecting a serial port to Multiple Rosemount 4088B
Transmitter (Multi-Drop) (3SRSG4)
You can wire any of the four serial ports for communication with multiple multi-dropped
Rosemount 4088B transmitters using RS-485 (2-wire).
When wiring to multiple Rosemount 4088B transmitters (multi-drop) using 2-wire RS-485,
follow this configuration:
Figure 2-35. COMn RS-485 (2-wire) Connection to Multiple 4088B Transmitters (Multi-
Drop)
1
2
3
4
Notes
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Installation
Enable AC termination using switches on last multi-dropped 4088B transmitter
RS-485 bus; twisted pair required
Up to ten 4088B transmitters allowed per port. All transmitters require an
external power supply. When communicating with more than six 4088Bs at 9600
baud, update times exceed once a second.
Connect cable shields to suitable Instrument Earth connection point
For COM1, n=1, pin numbers as follows: a=1, b=2, c=3, d=4, e=5
For COM2, n=2, pin numbers as follows: a=6, b=7, c=8, d=9, e=10
For COM3, n=3, pin numbers as follows: a=11, b=12, c=13, d=14, e=15
For COM4, n=4, pin numbers as follows: a=16, b=17, c=18, d=19, e=20
FB3000 RTU Instruction Manual
D301851X012
November 2023
45