Communications wiring
RTU Open v5
CARRIER CORPORATION ©2019
Integration Guide
All rights reserved
15
5
Connect the N2 EIA-485 network to the controller's
J19
Network Comm
port. Connect to
Net+
,
Net-
, and
SHLD
.
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.
6
Turn
on
the RTU Open's power.
Troubleshooting N2 communication
The most common communication problems result from not properly following the configuration steps outlined
above in this manual. Review all of the steps and use the following list to check your settings.
Verify accuracy of the following:
Hardware settings
for N2 (8 Data bits, No Parity, and 1 Stop bit):
Baud rate DIP switches DS2 and DS1 set to 9600 bps
Protocol DIP switches DS3 - DS6
Jumper set to EIA-485
Proper connection wiring
Unique rotary address switches 1 – 99. If controllers have duplicate addresses, network communication can
be lost.
Unique BACnet Device Instance numbers. Default is 16101XX, with the rotary address switches defining XX. If
controllers have duplicate device instance numbers, 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.
