Metasys NAE/NIE Architecture

Understanding the architecture of Johnson Controls Metasys Network Automation Engines (NAE) and Network Integration Engines (NIE) is fundamental to designing, programming, and maintaining Metasys building automation systems.

System Overview

Metasys Architecture Hierarchy

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NAE Series Overview

NAE Models

NAE55

• Mid-size automation engine
• 30,000 points capacity
• Integrated I/O options
• N2, BACnet, LON trunks

NAE85

• Large-scale engine
• Unlimited point capacity
• Enterprise integration
• High-performance processing

SNE Series

• Smaller footprint
• Cost-effective
• Limited capacity
• Ideal for small buildings

NIE vs NAE

Feature	NAE	NIE
Control Logic	Yes	No
Integration Only	No	Yes
Programming	Full	Limited
Cost	Higher	Lower
Use Case	Primary controller	Protocol gateway

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NAE Components

Hardware Architecture

Communication Interfaces

Ethernet Port

• Primary network connection
• Connects to BMS network
• Supports BACnet/IP
• Web interface access

N2 Bus

• Legacy JCI protocol
• RS-485 physical layer
• Up to 100 devices per trunk
• Multiple trunks supported

SA Bus

• Sensor/Actuator bus
• For integrated I/O
• Direct-wired points

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Software Architecture

Operating System

• Linux-based embedded OS
• Real-time control capability
• Web server integrated
• Database engine

Application Layers

Database Structure

• Object-oriented database
• Hierarchical organization
• Real-time data storage
• Historical data management

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Object Model

Object Hierarchy

Object Types

Hardware Objects

• NAE Engine
• Trunk definitions
• Device mappings
• I/O modules

Application Objects

• Analog/Binary/Multistate values
• Schedules
• Trends
• Alarm extensions

Logic Objects

• Control modules
• Calculations
• Sequences
• Interlocks

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Network Communication

BACnet Integration

NAE supports BACnet:

• BACnet/IP (primary)
• BACnet MS/TP (via router)
• Standard object types
• COV subscriptions

N2 Protocol

Legacy JCI protocol:

• Polling-based
• Master/slave architecture
• Device addresses 1-255
• Supports VMA, DX, etc.

IP Networking

NAE Network Requirements:
- Static IP or DHCP reservation
- Ports: 80 (HTTP), 443 (HTTPS)
- BACnet: 47808 (UDP)
- FTP: 21 (file transfer)

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Metasys UI Access

Web Interface

Access NAE via browser:

https://<NAE-IP-Address>/

MUI (Metasys UI)

• Modern HTML5 interface
• Dashboard views
• Equipment navigation
• Alarm management
• Trend viewing

SCT Access

System Configuration Tool:

• Windows application
• Engineering interface
• Programming capability
• Database management

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Redundancy Options

Server Redundancy

• Primary/standby ADS
• Automatic failover
• Database synchronization

NAE Considerations

• No native NAE redundancy
• Use parallel systems if critical
• Network redundancy possible

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Performance Considerations

Capacity Planning

NAE Model	Points	Devices	Trunks
NAE55	30,000	150	4 N2
NAE85	Unlimited	500+	8+

Optimization Tips

1. Distribute load across NAEs
2. Minimize cross-NAE references
3. Use appropriate poll rates
4. Archive historical data
5. Monitor memory usage

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Security Features

Authentication

• Local user accounts
• Active Directory integration
• Role-based access
• Session management

Network Security

• HTTPS encryption
• Certificate management
• Firewall configuration
• VLAN isolation

Audit Trail

• User action logging
• Configuration changes
• Alarm acknowledgments
• Access attempts

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Best Practices

Design

1. Right-size NAE selection
2. Plan trunk layouts
3. Minimize network hops
4. Document architecture
5. Plan for growth

Configuration

1. Use consistent naming
2. Organize object hierarchy
3. Configure appropriate alarms
4. Set up trending
5. Enable security features

Maintenance

1. Regular backups
2. Monitor performance
3. Apply firmware updates
4. Review alarm logs
5. Audit user accounts

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References

• Johnson Controls Metasys Technical Documentation
• Metasys NAE Technical Bulletin
• BACnet Standard (ASHRAE 135)

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Understanding NAE architecture helps you design better systems and troubleshoot faster. Take time to understand how the pieces fit together.