Niagara R2 to G3 (AX) Data Exchange - oBIX vs. BACnet IP

Issue

Factors to consider using oBIX vs. BACnet IP to exchange data between Niagara R2 and G3 systems

Product Line

TAC I/A Series

Environment

Niagara R2 version 522 and later

Niagara G3 version 3.4 and later

Cause

Planning factors to consider as to which method is better suited for the customer

Resolution

Either solution has pros and cons regarding implementation. One needs to think about what fits and how much engineering is required.

 If the R2 UNCs (Jaces) are nearly full (CPU and/or memory or less than 40% idle time), then oBIX probably can't be used . It requires some resources to drop in the obix service. But if their CPU usage is good (> 40% idle time) and the resource count isn't near the limit, the obix service should fit into the UNC.

With oBIX, one has access to much more information in the R2 station than with BACnet. BACnet just gives access to its standard objects (BV, BO, AV, AO, etc). oBIX would provide access to just about anything in the station, though some things might be in a string format. One could get trend logs and such using oBIX.  Please also note that R2 oBIX is server only - no R2 "shadow objects" exists to obtain remote oBIX data (e.g. from an G3 station).

For additional details, refer to the following documents:

Niagara AX-3.x oBIX Guide

Niagara R2 to Niagara AX via oBIX Engineering Notes

 

With BACnet IP, one would need to set all the R2 points 'Foreign Address' field for any point to be available to the G3 station.  Then, configure the G3 BACnet network, discover the R2 devices and points (Note that if the G3 station is a supervisor, or Enterprise Server, a BACnet license feature with the appropriate number of BACnet points must be purchased).  

A G3 supervisor PC should handle 5000 obix or BACnet points, provided the station is properly licensed.