Honeywell ComfortPoint Open CPO-PC400-W Manual page 23

Recommended connection for BACnet MSTPMSTP Buses with non-isolated RS485
Interfaces
R
T
GND_ISO 5V_ISO
Isola on
Barrier
5V
TX
GND RX
CPO-PC400/CPO-PC400-W/
CPO-PC400-UW
Fig. 14. Connection (L > 3 m) of RS485 interfaces 1, 2, or 3 (RS485 interface 1 shown) to a BACnet Bus
NOTES:
— Always power the CPO-PC400-W/CPO-PC400-UW with a transformer separate to the connected BACnet MSTP
modules.
— N = max. 30 modules
— Signal ground (signal reference) connection is recommended if not all devices are electrically isolated. For more
information, see "General Information on the RS485 Standard" section on page 7.
110VAC/230VAC
24VAC
F1
23
CPO-PC400-W/CPO-PC400-UW HVAC CONTROLLER
L > 3m
#1 #N
R
T
EN0B-0085 IE10 R0420