Communications wiring
RTU Open v5
CARRIER CORPORATION ©2019
Integration Guide
All rights reserved
13
Proper connection wiring
Wiring specifications are 18 - 28 AWG; twisted pair, and 50 feet (15.4 meters) maximum
Unique rotary address switches 1 – 99. If controllers have duplicate addresses, network communication can
be lost.
NOTES
If RX LED is solid, then the terminations are incorrect.
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.
The controller recognizes physical changes (DIP switches, rotary switches, and jumpers) upon power up.
BAS must be:
Set for the same baud rate
Sending requests to the proper address
Reading or writing to the proper point addresses on the controller
Set for the same communication settings (8 Data bits, No Parity, and 1 Stop bit)
Speaking 2-wire 485 to the controller
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.
NOTES
Refer to
Appendix A
(page 41) for the Network Points list.
Refer to
Appendix C
(page 56) for the Protocol Implementation Conformance Statement.
Modbus Exception Codes that might be returned from this controller
Codes
Name
Description
01
Illegal Function
The Modbus function code used in the query is not
supported by the controller.
02
Illegal Data
Address
The register address used in the query is not supported
by the controller.
04
Slave Device
Failure
The Modbus Master has attempted to write to a non-
existent register or a read-only register in the
controller.
