Carrier OPN-RTUM2, Integration Manual, Page: 17 / 61

Communications wiring
RTU Open v3 Carrier Proprietary and Confidential CARRIER CORPORATION ©2016
Integration Guide All rights reserved
13
Wire specifications
○
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
NOTE Use the same polarity throughout the network segment.
7 Turn
on
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 DS3 -
DS6 .
2
Verify that the BAS and the controller are both set for the same baud rate:
○
9600 for N2
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Baud rate DIP switches DS2 and DS1
○
Obtain a Modstat of the controller. Scroll to the bottom of the page to Network Communications 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.
NOTES
•
Refer to Appendix A (page 35) for the Network Points list.
• Refer to Appendix D (page 49) for the Protocol Implementation Conformance Statement.