Communications wiring
RTU Open v3 Carrier Proprietary and Confidential CARRIER CORPORATION ©2016
Integration Guide All rights reserved
13
○ A dedicated 22 AWG shielded twisted pair wire (EIA 485)
○ Maximum wire length 2000 feet (610 meters) or 32 nodes
○ Devices should be daisy-chained and not star-wired
○ Attach the drain/shield wire to both ends of the network segment and through every controller
Use the same polarity throughout the network segment.
7 Turn
the RTU Open's power.
Troubleshooting N2
Check the following to troubleshoot your RTU Open:
1 Verify that the BAS and controller are both set to speak N2 protocol on the Comm Selector DIP switches
.
2 Verify that the BAS and the controller are both set for the same baud rate:
○ 9600 for N2
○ Baud rate DIP switches DS2 and DS1
○ Obtain a Modstat of the controller. Scroll to the bottom of the page to
to view
the active protocol and baud rate.
3 Verify that the BAS is configured to speak 2-wire EIA-485 to the controller. The BAS may have to configure
jumper or DIP switches on their end.
4 Verify that the BAS and the controller have the same communication settings (8 data bits, No Parity, and 1
stop bit).
5 Verify proper connection wiring between the BAS and the controller.
6 Verify that the rotary address switches are set for the controller's unique slave address.
7 BAS must be reading or writing to the proper point addresses on the controller.
8 BAS is sending requests to the proper slave address of the controller.
• Refer to Appendix A (page 35) for the Network Points list.
• Refer to Appendix D (page 49) for the Protocol Implementation Conformance Statement.