Host-Based Architecture LON Communicat ion Gateway for Building Air-conditioner Monitoring System

Along with BACnet, LONWORKS is also increasingly accepted as a de-facto standard for building management communication protocol. A few years ago, Mitsubishi Heavy Industries developed these communication gateways for packaged air-conditioners,(1) but the recent market need is increasingly shifting to large capacity and high performance. In recent building management systems for packaged airconditioners, each of several hundred air-conditioners has about ten control points. When these air-conditioners are monitored and managed by LONWORKS, several thousand LON network variables must be handled. Because these variables are converted by LON communication gateways, the required number of gateway devices is determined depending on how many air-conditioners one gateway device can manage. Generally, it is said that gateway complexity increases but the total equipment cost and the required network configuration work both decrease when the number of gateway devices is reduced. Focusing on development technolog y, th is paper discusses the world's premier LON communication gateway for packaged air-conditioners that manages up to 96 aircondit ioners and ensures high speed communicat ion p er for ma nce w i t hout bot t lene cks even when L ON communication concentrates on one gateway.