P/N PM000223A • Rev. 1 • ISS 9 August 2017
15
Installation Manual
NU-Series Hardware
System Cabling
2.5
Hallway Bus
The hallway bus connects the Gateway II to Passive Bus Concentrators (NUPBC), Dome
Lights (NUDL2S / NUDL4S).
Figure 12 Hallway bus with dome light and NUPBC
Legend:
(1) Gateway II
(2) Power from Gateway II to hallway devices (+36V and GND)
(3) Hallway bus from Gateway II to hallway devices,
see “Daisy Chaining Hallway Devices”
(4) Passive Bus Concentrator (NUPBC)
(5) Dome Light (NUDL2S or NUDL4S)
The hallway bus uses unshielded Cat5/5e/6/7 cable. The hallway bus consists of four
unshielded twisted wire pairs that carry microphone, speaker, and ground. The data lines
use an RS485 bus. The voice lines are balanced microphone and speaker lines with one
twisted wire pair. One wire is for ground and the last wire is not used.
Figure 13 Hallway Bus connections