Metasys BACnet Integration
Metasys NAE controllers provide robust BACnet capabilities for integrating third-party devices and exposing Metasys points to other BACnet systems. This guide covers BACnet configuration and integration best practices.
BACnet Capabilities
Metasys as BACnet Server
NAE exposes Metasys objects as BACnet:
- All Metasys points visible as BACnet objects
- Standard BACnet services supported
- COV subscriptions available
- Alarm and event reporting
Metasys as BACnet Client
NAE integrates third-party BACnet devices:
- Device discovery
- Point mapping
- Polling and subscriptions
- Command execution
BACnet Configuration
NAE BACnet Settings
BACnet Network Configuration:
Device Instance: 100 (unique per site)
Device Name: "NAE-BLD1-01"
Network Number: 0
UDP Port: 47808
APDU Timeout: 3000ms
APDU Retries: 3
Device Instance Planning
Each BACnet device needs unique instance:
Device Instance Scheme:
100-199: NAE Controllers
200-299: Third-party AHU controllers
300-399: VAV controllers
400-499: Lighting controllers
500+: Reserved
Integrating Third-Party Devices
Device Discovery
- Configure BACnet trunk in SCT
- Set discovery parameters
- Right-click trunk → Discover
- Review discovered devices
- Add desired devices to database
Manual Device Addition
When discovery doesn't work:
Device Configuration:
Device Instance: 200
Device Name: "AHU-Controller"
MAC Address: 192.168.1.50
Network: 0
Max APDU: 1476
Point Discovery
After adding device:
- Select device in tree
- Right-click → Discover Points
- Select points to integrate
- Configure point properties
- Verify communication
Point Mapping
Object Type Mapping
| BACnet Object | Metasys Type | Notes |
|---|
| Analog Input (AI) | Analog Input | Read-only sensor |
| Analog Output (AO) | Analog Output | Commandable |
| Analog Value (AV) | Analog Value | Read/write |
| Binary Input (BI) | Binary Input | Status |
| Binary Output (BO) | Binary Output | Command |
| Binary Value (BV) | Binary Value | Configuration |
| Multi-State Input (MSI) | Multistate Input | Enumerated status |
| Multi-State Output (MSO) | Multistate Output | Mode command |
| Multi-State Value (MSV) | Multistate Value | Mode selection |
Point Configuration
BACnet Point Setup:
Object Type: Analog Input
Instance: 1
Property: Present Value
Poll Interval: 60 seconds
COV Enable: Yes
COV Increment: 0.5
Engineering Units: Deg F
Polling vs COV
Polling:
- Fixed interval requests
- Predictable network load
- Works with all devices
- Higher bandwidth usage
COV (Change of Value):
- Device sends on change
- Lower network traffic
- Requires device support
- May need fallback polling
BACnet MS/TP Integration
MS/TP Router Configuration
NAE as BACnet router:
MS/TP Trunk Setup:
Serial Port: COM1
Baud Rate: 76800
MAC Address: 1
Max Master: 127
Max Info Frames: 1
Network Number: 1
MS/TP Device Integration
- Configure MS/TP trunk
- Set network number (different from IP)
- Discover MS/TP devices
- Map devices and points
- Verify communication
MS/TP Best Practices
- Use highest supported baud rate
- Set Max Master appropriately
- Limit devices per trunk (32 recommended)
- Proper wiring and termination
BBMD Configuration
When BBMD is Needed
- Multiple IP subnets
- Devices across VLANs
- WAN connections
- Cloud integration
BBMD Setup
BBMD Configuration:
Enable BBMD: Yes
BDT (Broadcast Distribution Table):
Entry 1: 192.168.1.1/24
Entry 2: 192.168.2.1/24
Foreign Device TTL: 60 seconds
Foreign Device Registration
For devices on other subnets:
Foreign Device Setup:
BBMD Address: 192.168.1.50
Registration TTL: 60 seconds
Auto-Register: Enable
Exposing Metasys to BACnet
Object Visibility
Control which objects are BACnet-visible:
- Enable BACnet property per object
- Configure object instance numbers
- Set appropriate access (read-only/writable)
Security Considerations
- Limit writable objects
- Use BACnet authentication if available
- Monitor for unauthorized access
- Network segmentation
Alarms via BACnet
Alarm Notification
Configure alarm forwarding:
Notification Configuration:
Notification Class: 1
Priority: Normal
Transitions: To-Offnormal, To-Normal
Recipients: BACnet device list
Intrinsic vs Algorithmic
- Intrinsic: Built into point (high/low limits)
- Algorithmic: Separate alarm object
Troubleshooting
Communication Issues
Device Not Found
- Verify IP address/MAC
- Check firewall rules (47808/UDP)
- Confirm device instance unique
- Test with BACnet diagnostic tool
Points Not Updating
- Check poll interval
- Verify COV subscription
- Review device status
- Check network traffic
Intermittent Communication
- Check network stability
- Verify APDU settings
- Review timeout values
- Check for address conflicts
Diagnostic Tools
- BACnet traffic capture (Wireshark)
- SCT diagnostics
- Device vendor tools
- Third-party BACnet tools
Common Error Codes
| Error | Meaning | Solution |
|---|
| Timeout | No response | Check network/device |
| Unknown Object | Wrong instance | Verify object exists |
| Unknown Property | Property not supported | Use supported property |
| Write Access Denied | Not writable | Check device config |
Performance Optimization
Poll Rate Guidelines
| Data Type | Recommended |
|---|
| Critical alarms | 10-30 sec |
| Control values | 30-60 sec |
| Monitoring | 60-300 sec |
| Setpoints | 300+ sec |
Reducing Network Load
- Use COV where supported
- Increase poll intervals
- Limit monitored properties
- Group device polling
- Use appropriate timeouts
Best Practices
Design
- Plan device instance numbering
- Document all integrations
- Use consistent naming
- Plan for future expansion
- Consider bandwidth requirements
Implementation
- Test integration in lab
- Verify all points
- Configure appropriate polling
- Set up alarms
- Document configuration
Maintenance
- Monitor communication health
- Update firmware as needed
- Review performance regularly
- Backup configurations
- Document changes
References
- ASHRAE 135: BACnet Standard
- Johnson Controls BACnet Integration Guide
- BACnet International resources
- Metasys Technical Documentation
BACnet integration opens up Metasys to a world of third-party devices. Take time to understand both sides of the integration for the best results.