N - Metasys - LIT-1201612 - General System Information - Metasys System - 12.0

Metasys System Glossary

Product name
Metasys System
Document type
Technical Bulletin
Document number
Revision date
Product status

N2 Bus

An RS-485 communications bus based on the Opto-22® Optomux® protocol. The N2 Bus is used primarily by legacy Metasys field controllers to communicate with supervisory controllers. Media choices for N2 Bus communication include two-wire, twisted pair telephone wire, a three-wire twisted cable, and duplex optical fiber. The MS/TP Bus supersedes the N2 Bus.


Network Automation Engine. The NAE is a Web-enabled, Ethernet-based supervisory controller that monitors and supervises networks of field-level building automation devices that control HVAC equipment, lighting, security, and building access. The NAE provides alarm and event management, trending, archiving, energy management, data exchange, scheduling, dial features, and password protection. Different models and options support various communications networks including the N2 Bus, BACnet network, and LonWorks network. Newer versions of the NAE also support third-party protocols, including Modbus, M-Bus, and KNX.

Navigation panel

A graphical representation of the spaces and network components of the building automation system as controlled by the Metasys UI. The Navigation panel is located on the left side of the screen and facilitates the navigation through the Spaces and Building Network trees.

Navigation tree

A tree-like representation of the Metasys network as shown in the Site Management Portal UI.


Network Control Engine. A controller that combines the network supervisor capabilities and IP network connectivity of an NAE with the input/output point connectivity and direct digital control capabilities of an FEC. Newer versions of the NCE also support third-party protocols, including Modbus, M-Bus, and KNX.

Network Address Translation (NAT)

A system of translation that enables a device on a LAN to use one set of IP addresses for internal traffic and a second set of addresses for external traffic.

Network Engine

Generic title used to identify any supervisory engine including NCEs, NAEs, NIEs, SNEs, and SNCs.

Network Sensors (NS)

Network sensors are devices that connect to a controller to monitor and record the physical conditions of the environment.

NT LAN Manager (NTLM)

A network authentication protocol developed by Microsoft Corporation. NTLM is the secondary protocol for authentication within an Active Directory service domain. If a domain client or domain server cannot use Kerberos authentication, then NTLM authentication is used.