Specifications
Table Of Contents
- Introduction
- Installation Procedures
- Commissioning Procedures
- Troubleshooting Procedures
- Overview
- Checking for Good Wire Runs
- Checking for Proper Termination
- Checking the End-of-Line Device Settings
- Checking for Proper Channel Selection
- Checking the N2 Device
- Checking the Number of Defined N2€Devices
- Checking the Length of N2€Bus
- Checking for “T” or “Y” Connections
- Checking for a Ground Loop
- Checking the Repeater
- Checking the Surge Protector
- Checking the Communication Terminal Board
- Checking Communication Faults
- Ordering Instructions
Network Communications—N2 Communications Bus
3
Introduction
The N2 Communications Bus is a local network that links controllers and
point interfaces to the Network Control Module (NCM). The N2 Bus uses
a master/slave protocol, in which the master 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