Communications wiring
RTU Open v3
Carrier Proprietary and Confidential
CARRIER CORPORATION ©2016
Integration Guide
All rights reserved
10
EXAMPLE
To set the controller's Modbus slave address to 01, point the arrow on the
MSB
(
SW1
) switch to 0
and the arrow on the
LSB
(
SW2
) switch to 1.
3
Set the
SW3
Comm Selector DIP switches
DS1
and
DS2
for the appropriate communications speed (9600,
19.2k, 38.4k, or 76.8k bps).
NOTE
Use the same baud rate and communication settings for all controllers on the network segment. The
RTU Open is fixed at 8 data bits, No Parity, and 1 Stop bit for this protocol's communications.
Baud Selection Table
Baud Rate
SW3/DS2
SW3/DS1
9,600
Off
Off
19,200
On
Off
38,400
Off
On
76,800
On
On
4
Set
SW3
Comm Selector DIP switches
DS3
through
DS6
for Modbus. See example below.
5
Leave
DS7
and
DS8
in the OFF position. These switches are not applicable to Modbus.
SW3 Protocol Switch Settings for Modbus
DS8
DS7
DS6
DS5
DS4
DS3
Off
Off
Off
On
On
Off
The following example shows the DIP switches set for 9600 baud and Modbus.
6
Connect the Modbus EIA-485 network to the RTU Open's
J19
port. Connect to
Net+
,
Net-
, and
SHLD
.