Xylem 205546 Modbus Communication Modules for Displays - Manual (Page 11)

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2.1.5 Connection Examples
2.1.5.1 One Connected Unit
This example illustrates connection, termination and ID configuration of a
single unit 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
B
A
GND
PE
PLC
Unit #1
Figure 3. One Connected Unit
Exampe ID settings
If the connected unit has ID=1 (seen from the com module), and the com
module has ID offset=200, the SRO Modbus ID is “201” (200 + 1, seen from
the PLC).
Termination
Modbus RS 485 communication requires bus termination. Therefore the con-
nected COM module’s termination dip switch is set in “ON” position.
2. Communication Modules
Modbus Communication Modules