Modbus Connection; Modbus Considerations - Honeywell CENTRA LINE EAGLEHAWK NX Installation & Commissioning Instructions

EAGLEHAWK NX CONTROLLER – INSTALLATION & COMMISSIONING INSTRUCTIONS

MODBUS CONNECTION

The EAGLEHAWK NX controller supports both Modbus RTU master and Modbus RTU slave functionality.
Modbus slaves can be connected to either or both of the two onboard RS485 interfaces: RS485-1 (consisting of push-in
terminals 24 [GND-1], 25, and 26) or RS485-2 (consisting of push-in terminals 29, 30, 31 [GND-2]).
NOTE: GND-2 is internally connected with 24V-0 (terminal 1)

Modbus Considerations


RS485-1 (isolated)
˗ Max. Modbus length: 1200 meters (9.6 – 78.8 kbps) or 800 meters (115.2 kbps) (see also section "RS485 Standard" on
pg. 10).
˗ Use only shielded, twisted-pair cable and daisy-chain topology.
˗ Must conform to EIA-RS485 cabling guidelines (see section "EIA 485 Cable Specifications" on pg. 35).

RS485-2 (non-isolated)
˗ Max. Modbus length: 1200 meters (9.6 – 78.8 kbps) or 800 meters (115.2 kbps) (see also section "RS485 Standard" on
pg. 10).
˗ Use only shielded, twisted-pair cable and daisy-chain topology.
˗ Ground noise should not exceed the EIA-485 common mode voltage limit.
˗ Must conform to EIA-RS485 cabling guidelines (see section "EIA 485 Cable Specifications" on pg. 35).
˗ Should not extend beyond a single building.

Max. no of Modbus devices per EAGLEHAWK NX RS485 interface: 32 (including the EAGLEHAWK NX, itself, which
is counted twice)
43 EN1Z-1039GE51 R1218