[NickDeal]

BACnet is becoming the industry standard for the most part. Siemens is pushing you that way because they never did LON very well and haven't pursued the protocol since the last iteration of their product line. If you go with LON chillers Siemens will either try and purchase MECs with a LON license and install them or will go to field server or some other manufacturer and get a gateway to translate the points into BACnet anyway. There are several issues with doing either of these options. Using the first option you would be getting obsolete controllers to which Siemens has abandoned support for the most part. All of the point mapping would have to go through Buffalo Grove making changes difficult and costly. Going the second route you have more costly repairs, difficulty making changes.

As for LON vs BACnet there are advantages and disadvantages to both protocols. LON's FT-10 is more robust when it comes to wiring issues and noise compared to EIA485, but LON chips require a credit and usually a thick client to setup and maintain the network database.