Communications wiring
RTU Open v5
CARRIER CORPORATION ©2019
Integration Guide
All rights reserved
11
If the network has greater than 32 devices or exceeds 2,000 feet, a Repeater should be installed.
If a controller begins or ends a network segment, a terminating resistor may be needed.
Software settings
defined through the Equipment Touch device. To confirm settings, obtain a Modstat of the
device. On the Equipment Touch, click the link to the Modstat.
Modbus
To set up the RTU Open for Modbus
Refer to
Appendix C
(page 56) for the Modbus Protocol Implementation Conformance Statement (PICS).
1
Turn
off
the RTU Open's power.
NOTE
Changes made to the switches when the controller is on will not take effect until the power is cycled!
2
Using the rotary switches, set a unique Modbus slave address for the RTU Open. Set the
MSB
(
SW1
) switch to
the tens digit of the address, and set the
LSB
(
SW2
) switch to the ones digit. Valid Modbus slave addresses
are 01-99.
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.
10's
1's
1
3
45
2
7
8
9
6
0
1
3
45
2
7
8
9
6
0
SW1
SW2
M SB
LSB
3
Set the
SW3
DIP switches
1
and
2
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 DIP switch settings
Baud rate
2
1
9,600 bps
Off
Off
19.2 kbps
On
Off
38.4 kbps
Off
On
76.8 kbps
On
On
