Research And Application Of BACnet-based Gateway In Building Enertgy-saving Control System

Building energy efficiency is one of the hot issues of common concern in today's society, the establishment of building energy-saving control system provides a new direction for realizing an effective energy-saving building. With the development of computer technology and control technology, building energy-saving automation system is growing forward to intelligence, integration and network. BACnet protocol is a communication protocol which is especially to carry out the integrated control problem of building device,it has solved the problems that the equipment is not compatible and difficult to integrate in building automation system, and also provides a unified communication language for the realization of different building automation system. BACnet protocol will be applied to building energy-saving control system for systematic control and management of construction equipment, optimizing the operation of various types of construction equipment. It is an effective way to reduce building energy construction.Firstly , this dissertation analyzes the limitations of traditional building energy-saving control systems, proposes to combine the BACnet protocol with building energy-saving control system, analyzes the theory of the BACnet protocol and embedded technology, and on this basis apply the BACnet protocol to establish a building energy-saving control system, which improves the system's openness and integration.Secondly, based on analyzing of the system's function, the dissertation is researched and designed an important part of the system-the gateway. Hardware part is designed by modular chips, it has simple and reliable structure, on the base of chip choosing of CPU core module, communication interface module, external expansion memory module and the basic modules, it has designed the chip schematic. Using the procedure, software part achieves the communication of the underlying low-speed control device and the upper control center. From the perspective of gateway application, it has achieved the cutting of TCP/IP protocol stack, defined and selected the BACnet object and application services of underlying communication. It has put emphasis on the encoding and decoding of BACnet application layer and network layer, also on the creation of MS/TP frames in the data link layer.Lastly,through the starting self-test and data transceiver tests of the gateway, it has demonstrated the correctness, reliability and security of gateway software.