Bacnet™ Ms/Tp Wiring Example; Bacnet ™ Ms/Tp Wiring Setup Using Signal Common Example - Honeywell Unitary Installation Instructions Manual

HONEYWELL UNITARY CONTROLLER - 230 VAC - INSTALLATION INSTRUCTIONS
TM
BACnet MS/TP Wiring Example
RS485
RS485 Reference
PLANT CONTROLLERS
NOTE:
• Suppose any of the devices are electrically isolated. It is recommended that those devices be connected to
the ground terminal (SHLD). See TIA/EIA 485 Cable Specifications.
• The 120 Ω termination resistor must be inserted directly into the terminals of both end devices.
• If shielding is used, the shielding of each individual bus segment should be separately connected at one end
to a verified earth ground.
• Always power each controller and the connected slaves via separate transformers.
• Between devices equipped with non-isolated RS-485 bus interfaces, potential differences of max. ±7 VDC are
allowed. Further, this bus should not extend beyond a single building.
• The SHLD (terminal 44) on the BACnet™ MS/TP controller is a free-floating terminal and is not connected to
any signal common.
TM
BACnet MS/TP Wiring Setup Using Signal Common Example
RS485
RS485 Reference
PLANT CONTROLLERS
NOTE:
1) A single twisted pair has to be used for terminal 42 (+) and terminal 43 (-).
2) Terminal 47 can be used as COM for BACnet™ MS/TP wiring.
3) The plant controller is displayed on the above diagram for illustration purpose only. Kindly refer to the plant
controller documentation for more details about the wiring.
31-00610-01
Shield
RS485 +
-
Fig. 22 Connection to a BACnet™ MS/TP Bus
Shield
Signal Common
+
RS485
-
Fig. 23 Connection to BACnet MS/TP Bus (signal common)
BACnet MS/TP CONTROLLER
+ - SHLD
BACNET MS/TP UNITARY CONTROLLER
LEGACY CONTROLLER
MS/TP 1
C1+ C1- +
GND
42
26
BACnet MS/TP CONTROLLER BACnet MS/TP CONTROLLER
+ - SHLD
LEGACY CONTROLLER
RS485 1
+ -
- COM
SHLD
43 44 45 46 47
Shield
+
- SHLD
120
Shield
C1+ C1- GND
120
Signal Common