Performance considerations - Verasys - LIT-12013606 - LC-SBH200-0 - BACnet integration - Verasys System - 4.0

Verasys BACnet MS/TP Integration Technical Bulletin

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Verasys System
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Technical Bulletin
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Network performance can degrade when you add third-party devices on the same MS/TP trunk if those devices do not meet the minimum requirements in the following table. To improve network performance, ensure that third-party devices also meet the preferred requirements.

Table 1. Third-party BACnet device performance requirements
Requirement group Requirement
Devices on MS/TP trunk MS/TP master device available on the MS/TP trunk Yes Minimum
Baud rate 38.4kbps Minimum
APDU size 480 bytes Acceptable
200 bytes Preferred
Segmentation on MS/TP Yes Acceptable
BACnet services BACnet protocol version Version 1 revision 4 or higher Acceptable
Version 1 revision 15 or higher Preferred
Device profile B-SA or B-SS Minimum
BACnet certified Yes Minimum
BACnet Interoperability Building Blocks (BIBBs) Read Property Multiple Preferred
Subscribe COV Preferred
Third-party BACnet devices have the following performance limits:
  • The maximum number of devices on system bus drops from 100 to 50 if a third-party BACnet device connects.
  • The maximum number of devices further drops to 30 if any third-party BACnet device does not support BACnet subscribe COV service.
  • Do not exceed 250 objects of a supported type for each BACnet device.
  • Do not exceed 30 alarm extensions for each device.
  • Do not exceed 30 trend extensions for each device.