Optimize BACnet MSTP Data Throughput in Niagara R2 Systems

[Product_Support]

Issue

How can a BACnet system be customized to maximize data throughput?
The site has a Niagara R2 Enterprise Server and a UNC with multiple MSTP controllers connected.

Product Line

TAC IA Series

Environment

• Niagara R2 Enterprise
• UNC
• MSTP controllers

Cause

Improper BACnet configuration and default settings can lead to inefficient communication and slow system performance.

Resolution

Follow these best practices to improve BACnet MSTP performance:

1. Remove Unused BACnet Objects

   • Delete unnecessary BACnet objects learned into the station.
   • Move non-critical objects from Poll-Always to Poll-on-Demand containers.

2. Optimize Controller Addressing

   • Ensure all MSTP controllers are consecutively addressed.
   • Avoid gaps in addressing to reduce communication delays.

   Benefits of Consecutive Addressing:

   • Faster Token Passing: Token moves quickly without searching for missing addresses.
   • Reduced Token Search Overhead: Minimizes wasted polling cycles caused by gaps.
   • Easier Troubleshooting: Simplifies device identification and network verification.
   • Optimized MaxMaster Setting: Predictable and efficient configuration.

3. Set Correct MaxMaster Value

   • Configure MaxMaster in all controllers and the UNC to two greater than the highest MSTP address.
   • Example: If highest address = 20, set MaxMaster = 22.
   • Leaving MaxMaster at 127 with only 20 controllers causes unnecessary token searches.

4. Adjust MaxInfoFrames

   • Set MaxInfoFrames in the UNC or MNB-1000 to between 5 and 20.
   • Default is 1, which results in sluggish updates.
   • Start at 5 and increase gradually to find the optimal performance point.

5. Reference Documentation

   • See I/A Series MicroNet BACnet Wiring, Networking, and Best Practices Guide (F-27360) for detailed recommendations.