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Modbus Connection; Modbus Considerations; Connecting Eaglehawk Via Its Rs485-1 Interface To A Modbus - Honeywell CENTRA LINE EAGLEHAWK Installation & Commissioning Instructions

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MODBUS CONNECTION

The EAGLEHAWK 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: 800-1200 meters, depending on baud rate (see section "RS485 Standard" on pg. 8).
˗
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. 18).
RS485-2 (non-isolated)
˗
Max. Modbus length: 800-1200 meters, depending on baud rate (see section "RS485 Standard" on pg. 8).
˗
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. 18).
Should not extend beyond a single building.
˗
Max. no of Modbus devices per EAGLEHAWK: 32 (including the EAGLEHAWK, itself, which is counted twice)

Connecting EAGLEHAWK via its RS485-1 Interface to a Modbus

With regards to Fig. 37, please note the following:
NOTE:
Always power each EAGLEHAWK controller and the connected Modbus slaves via separate transformers.
NOTE:
For "L," see section "RS485 Standard" on pg. 8.
NOTE:
If any devices are not electrically isolated, signal ground connection is recommended. See section "RS485 Standard"
on pg. 8).
Example: EAGLEHAWK Modbus Master Controller and Connected Modbus Slaves (with inserted termination
resistor)
EAGLEHAWK
242526
GND-1
+5V
GND-1
ISO
Module #2
550 OHM
150 OHM
550 OHM
RS485-1 (+) RS485-1 (-)
END
1 2
Modbus
Module #1
F1
24 V
230 V
Fig. 37. Connection of an EAGLEHAWK Modbus master controller via its RS485-1 interface to a Modbus with slaves
The termination resistor must be inserted directly into the terminals of the last Modbus slave.
NOTE:
If an EAGLEHAWK connected to a Modbus via its RS485-1 interface is itself to be used as a Modbus RTU slave, and
if it is situated in a position other than the beginning or end of the Modbus, then its 3-position slide switch must be set
to "Mid" (see Fig. 11). When situated at the beginning or end of the Modbus, then its 3-position slide switch must be
set to "End" (see Fig. 13).
EAGLEHAWK CONTROLLER – INSTALLATION & COMMISSIONING INSTRUCTIONS
Modbus
Modbus
Module #3
*CONNECT GND, IF AVAILABLE.
L
Modbus
Module #4
23
Modbus
Modbus
Module #N-1
Module #N
EN1Z-1005GE51 R0216
R
T
120 OHM

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