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2 three connected units, Modbus communication modules, Gnd b a gnd gnd rs485 – Xylem 205546 Modbus Communication Modules for Displays User Manual

Page 12: Unit #3, Unit #2, B a gnd pe plc unit #1, Figure 4. three connected units, Termination off on

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EN 6.81 Modbus Communication Module 205546 Manual 1212

2.1.5.2 Three Connected Units

This example illustrates connection, termination and ID configuration of three
units each with a communication module and a PLC.

GND
B
A
GND

GND

RS485

Termination OFF

ON

GND GNDB

PCB no.: 510327-xxx
Communication RS485

3V3

5V5

5V
RTS

Rx

Tx

3V3

GND
B
A
GND

GND

RS485

Termination OFF

ON

Unit #3

GND
B
A
GND

GND

RS485

Termination OFF

ON

GND GNDB

PCB no.: 510327-xxx
Communication RS485

3V3

5V5

5V
RTS

Rx

Tx

3V3

GND
B
A
GND

GND

RS485

Termination OFF

ON

Unit #2

GND
B
A
GND

GND

RS485

Termination OFF

ON

GND GNDB

PCB no.: 510327-xxx
Communication RS485

3V3

5V5

5V
RTS

Rx

Tx

3V3

GND
B
A
GND

GND

RS485

Termination OFF

ON

B
A
GND

PE

PLC

Unit #1

Figure 4. Three Connected Units

Modbus Communication Modules