Research And Design On BACnet-MS/TP Based On The Embedded Technology

BACnet (A Data Communication Protocol for Building Automation and Control Network) is an open building automation network data communication protocol, designed specially for the building automation and control systems, funded by the United States Heating, Refrigeration and Air-conditioning Institution of Engineer (ASHRAE), declared a formal ISO standard by the International Standardization Organization (ISO). That is, ISO16484-5. The fundamental purpose of BACnet is to provide interoperable way for building automation systems, MS/TP (Master-Slave/Token-Passing) protocol as one of BACnet datalink layer options, widely used in BACnet product for its real-time performance, stability and reliability characteristics. Therefore, research and implementation of MS/TP protocol based on the embedded technology have a very important role in promoting the use and popularization of MS/TP and BACnet, accelerating the development process of intelligent building.The project researches on the software and hardware design scheme of MS/TP protocol in the embedded platform, proposed a modular design scheme, given the hardware and software realization details, finally carried on the network test with the standard BACnet equipment and passed the VTS testing of BACnet testing laboratory. For the problems of MS/TP protocol encountered in the practical project, we study on the MS/TP protocol itself in-depth, proposed a dynamic bandwidth allocation algorithm for MS/TP network real-time bandwidth, which can adjust the bandwidth distribution of various master nodes according to single master node network load and the entire network load dynamically, enhanced the real-time and network throughput, resolved the MS/TP protocol QoS guarantee in the MAC layer, and further enhanced the network reliability. The main tasks of this paper include the following:(1) Proposed a MS/TP protocol modular design program, given the MS/TP protocol software and hardware implementation program in the embedded platform. (2) Proposed two MAC layer QoS guarantee methods, provided a better solution to the MS/TP protocol transmission reliability problem.(3) Proposed a dynamic allocation algorithm for MS/TP real-time network bandwidth, enhanced the real-time performance and the network throughput.(4) Adopting the object-oriented analysis and design methods, BACnet standard has been applied to mechanical and electrical equipment industry, this is the first attempt of BACnet standard used in the practical project.(5) For the wireless network technology development status, proposed a self-organizing wireless token ring network based on MS/TP protocol, which will benefit the further expansion of MS/TP protocol applications.