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Connecting Eaglehawk Via Its Rs485-2 Interface To A Modbus - Honeywell CENTRA LINE EAGLEHAWK Installation & Commissioning Instructions

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EAGLEHAWK CONTROLLER – INSTALLATION & COMMISSIONING INSTRUCTIONS

Connecting EAGLEHAWK via its RS485-2 Interface to a Modbus

With regards to Fig. 38, 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).
NOTE:
Between devices equipped with non-isolated RS485 bus interfaces, potential differences of max. ±7 V are allowed.
Further, this bus should not extend beyond a single building.
Example: EAGLEHAWK Modbus Master Controller and Connected Modbus Slaves (with inserted termination
resistor)
EAGLEHAWK
2930 31
GND-2
+5V
GND-2
Module #2
550 OHM
130 OHM
550 OHM
RS485-2 (+) RS485-2 (-)
NO EFFECT ON RS485-2
1 2
Modbus
Module #1
F1
24 V
230 V
Fig. 38. Connection of an EAGLEHAWK Modbus master controller via its RS485-2 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 RS485-2 interface is itself to be used as a Modbus RTU slave,
then it must be situated in a position at the beginning or at the end of the Modbus; this is because the bias and
termination resistors of its RS485-2 interface are always ON (see Fig. 14).
EN1Z-1005GE51 R0216
Modbus
Modbus
Module #3
*CONNECT GND, IF AVAILABLE.
L
Modbus
Module #4
24
Modbus
Modbus
Module #N-1
Module #N
R
T
120 OHM

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