Johnson Controls Metasys N2 User Manual

Network Communications—N2 Communications Bus
3
Introduction
The N2 Communications Bus is a local network that links contr
ollers and
point interfaces to the Network Control Module (NCM). The N2 Bus uses
a manager/subordinate protocol, in which the manager device, the NCM,
initiates all communication with the N2 Bus devices. These N2 Bus
devices include the Digital Control Modules (DCMs), Point Multiplex
Modules (XBN, XRE, XRL, XRM), and all Application Specific
Controllers (ASCs).
Figure 1 shows an example of several devices connected to the N2 Bus.
Note that the N2 Bus is wired in a daisy-chained fashion, in which
multiple devices are connected in series. The N2 Bus can use either solid
or stranded wire. It can also use optical fiber when special fiber modems
are used. Choices include:
• 3-wire twisted cable
• two twisted pair telephone cable
• two twisted pair cable with a shield
• duplex optical fiber (requires pair of fiber modems)
N2EXAMPL
NCU
N2 Bus
N1 LAN
ASC
(ILC Shown)
NEU
NEU
Figure 1: Example of an N2 Bus Layout
Application
Details

Johnson Controls Metasys N2 Specifications

General

Brand	Johnson Controls
Model	Metasys N2
Category	Cables and connectors
Language	English