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Bacnet Ms/Tp Bus Connection; Considerations; Connecting Rs485-1 To Bacnet Ms/Tp Buses - Honeywell Centra Line EAGLE Installation & Commissioning Instructions

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BACNET MS/TP BUS CONNECTION

The EAGLE Controller features two RS485 interfaces to which BACnet MS/TP devices can be connected: RS485-1 (consisting
of push-in terminals 24 [GND-1], 25, and 26) and/or RS485-2 (consisting of push-in terminals 29, 30, and 31 [GND-2]).
NOTE:
GND-2 is internally connected with 24V-0 (terminal 1) and system GND (terminals 19+37)

Considerations

RS485-1 (isolated)
˗
Max. BACnet MS/TP bus length: 800-1200 meters, depending on baud rate (see section "RS485 Standard" on pg. 8)
˗
Must conform to EIA-RS485 cabling guidelines
RS485-2 (non-isolated)
˗
Max. BACnet MS/TP bus length: 1200 meters
˗
Use only shielded, twisted-pair cable
˗
Ground noise should not exceed the EIA-485 common mode voltage limit
Must conform to EIA-RS485 cabling guidelines
˗
Max. no. of BACnet MS/TP devices per RS485 interface: 32
Max. no of BACnet MS/TP devices per EAGLE: 64

Connecting RS485-1 to BACnet MS/TP Buses

242526
GND-1
+5V
ISO
47 kOHM
RS485-1 (+) RS485-1 (-)
1 2
F1
24 V
230 V
NOTE:
Always power the EAGLE and connected BACnet MS/TP modules with separate transformers.
NOTE:
N = max. 30 modules.
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).
Termination resistors must be inserted directly into the terminals of the individual BACnet MS/TP modules. In the above figure,
the EAGLE is shown operating as the Master BACnet controller; its slide switch is hence set to "MID."
EAGLE CONTROLLER – INSTALLATION & COMMISSIONING INSTRUCTIONS
EAGLE
GND-1
47 kOHM
MID
Fig. 33. Connection of RS485-1 to a BACnet MS/TP Bus
L
*
BACnet
Module #1
*Connect, if available.
23
120 Ohm
*
BACnet
Module #N
EN1Z-0970GE51 R1112
R
T

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