Honeywell ComfortPoint Open CPO-PC400-W Manual page 29

Connection to Modbus devices with non-isolated RS485 interfaces
R
T
5V_ISO
GND_ISO
Isola on
Barrier
5V
RX TX
GND
CPO-PC400-W/CPO-PC400-UW
Fig. 20. Connection (L > 3 m) of RS485 interfaces 1, 2, or 3 (RS485 interface 1 shown) to a Modbus
NOTES:
— N = max. 30 unit loads. Always power the CPO-PC400-W/CPO-PC400-UW and connected Modbus modules
with separate transformers. Termination resistors must be inserted directly into the terminals of the individual
Modbus modules.
— Signal ground (signal reference) connection is recommended. For more information, see "General Information
on the RS485 Standard" section on page 7.
— For communication cable lengths, transmission speeds, and termination, see "General Information on the
RS485 Standard" section on page 7. For fusing, see "Fusing" section on page 11.
110VAC/230VAC
24VAC
F1
29
CPO-PC400-W/CPO-PC400-UW HVAC CONTROLLER
L > 3m
Modbus
Module #1
Modbus
Module #N
R
T
EN0B-0085 IE10 R0420