EAGLEHAWK CONTROLLER – INSTALLATION & COMMISSIONING INSTRUCTIONS
Connecting EAGLEHAWK via its RS485-2 Interface to a Modbus
With regards to Fig. 38, please note the following:
Always power each EAGLEHAWK controller and the connected Modbus slaves via separate transformers.
For "L," see section "RS485 Standard" on pg. 8.
If any devices are not electrically isolated, signal ground connection is recommended. See section "RS485 Standard"
on pg. 8).
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
RS485-2 (+) RS485-2 (-)
NO EFFECT ON RS485-2
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.
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).
*CONNECT GND, IF AVAILABLE.