19
®
RS485 interface
The RS485 cabling must be overall shielded 3-conductor PVC insulated 22AWG-7/30, 300V 80°C
(7/0.2mm) wire. Terminate the screen shield at one unit only using the cable clamp provided.
For details on connecting NX Series integrated burner controllers and a PC onto the communications
bus, refer to bulletins NEX-1501(ComView combustion analysis tool) or NEX-SO (boiler sequenc-
ing). Refer to the following table for terminal identification.
FIGURE 8.
FIGURE 9.
Display Connection
The display cabling must be overall shielded 6 conductor PVC insulated 22AWG-7/30, 300V 80°C
(7/0.2mm) wire. Wiring must comply with all applicable codes, ordinances and regulations and,
where required, must comply to the NEC Class 1 (Line Voltage) wiring. Since this cable may be run
in conduit with other wiring, its voltage rating must exceed the maximum voltage carried by any
other cable in the same conduit.
RS485
EXPANSION MODULE/SEQUENCING
COMFIRE/COMMUNICATIONS
+
PD8
PD11
GROUND
PD7
PD10
-
PD9
PD12
SHIELD
ON ONE UNIT ONLY
ON ONE UNIT ONLY
RS485
COMMS
BUS
TO
PC/NX
PD10
CONTROLLER
CABLE SHIELD
PD12 PD11
+ GND -
PD10 PD12 PD11
+ GND -
PD10 PD12 PD11
+ GND -
INTEGRATED BURNER CONTROLLER
DISPLAY BOARD
•
1 +5v
•
2 KEY RETURN
•
3 DATA
•
4 CLOCK
•
5 SERIAL
•
6 Ov
PD 1 (+5v)
PD 2 (KEY RETURN)
PD 4 (CLOCK)
PD 5 (SERIAL)
PD 6 (Ov)
PD 3 (DATA)
•
SHIELD SHOULD BE SECURED
TO THE ENCLOSURE USING
CABLE CLAMP BAR.
MAXIMUM SHIELD TAIL LENGTH
SHOULD BE 4” (100mm).
CUT BACK INSULATION, EXTRACT
SCREENING BRAID AND COVER WITH
SLEEVING. FIT CRIMP RING TO END OF TAIL.
•
•
•
•
•
•
7
*Pay particular attention to the corresponding
terminal location on the display: PDI to #1,
PD2 to #2, PD3 to #3, PD4 to #4, PD5 to #5,
PD6 to #6, #7 on the display is unused.
