EAGLEHAWK NX CONTROLLER – INSTALLATION & COMMISSIONING INSTRUCTIONS
EN1Z-1039GE51 R1218
42
Connecting EAGLEHAWK NX via its RS485-2 Interface to a BACnet MS/TP Bus
With regards to Fig. 47 and Fig. 48, please note the following:
NOTE:
Always power each EAGLEHAWK NX controller and the connected BACnet MS/TP modules via separate transformers.
NOTE:
For "L," see section "RS485 Standard" on pg. 10.
NOTE:
If any of the devices are electrically isolated, it is recommended that those devices be connected to signal ground. See
section "RS485 Standard" on pg. 10.
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 1: Single EAGLEHAWK NX Controller and Connected BACnet Modules (with inserted termination
resistor)
1 2
24
V~
24
~
0
2930 31
GND-2
GND-2
+5V
RS485-2 (+) RS485-2 (-)
550 OHM
550 OHM
130 OHM
F1
230 V
24 V
R
T
BACnet
Module #2
RS
48
5
+
RS
48
5
-
GN
D
BACnet
Module #3
BACnet
Module #4
BACnet
Module #N-1
BACnet
Module #N
RS
48
5
+
RS
48
5
+
RS
48
5
+
RS
48
5
+
RS
48
5
-
RS
48
5
-
RS
48
5
-
RS
48
5
-
GN
D
GN
D
GN
D
GN
D
L
BACnet
Module #1
EN
D
BI
A
S
MID
NO EFFECT ON RS485-2
*CONNECT GND, IF AVAILABLE.
120 OHM
EAGLE-
HAWK NX
Fig. 47. Connection of a single EAGLEHAWK NX controller via its RS485-2 interface to a BACnet MS/TP Bus
The termination resistor must be inserted directly into the terminals of the last BACnet MS/TP module.
Example 2: Multiple EAGLEHAWK NX Controllers and Connected BACnet Modules
1
1
2
2
24
V~
24
V~
24
~
0
24
~
0
29
29
30
30
31
31
GND-2
GND-2
GND-2
GND-2
+5V
+5V
RS485-2 (+)
RS485-2 (+)
RS485-2 (-)
RS485-2 (-)
550 OHM
550 OHM
550 OHM
550 OHM
130 OHM
130 OHM
F1
F1
230 V
230 V
24 V
24 V
1
1
2
2
24
V~
24
V~
24
~
0
24
~
0
24
24
25
25
26
26
RS
48
5
+
RS
48
5
-
GN
D
BACnet
Module
RS
48
5
+
RS
48
5
-
GN
D
F1
F1
230 V
230 V
24 V
24 V
L
GND-1
GND-1
+5V
ISO
+5V
ISO
RS485-1 (+)
RS485-1 (+)
RS485-1 (-)
RS485-1 (-)
47 kOHM
47 kOHM
EN
D
BI
A
S
MI
D
MID
EN
D
BI
A
S
MI
D
MID
*CONNECT GND, IF AVAILABLE.
GND-1
47 kOHM
GND-1
47 kOHM
BACnet
Module #1
BACnet
Module #2
BACnet
Module #3
BACnet
Module #N-1
BACnet
Module #N
EN
D
BI
A
S
MID
NO EFFECT ON RS485-2
EN
D
BI
A
S
MID
NO EFFECT ON RS485-2
EAGLE-
HAWK NX
EAGLE-
HAWK NX
EAGLE-
HAWK NX
EAGLE-
HAWK NX
Fig. 48. Connection of multiple EAGLEHAWK NX controllers via their RS485-2 interfaces to a BACnet MS/TP Bus