Real-time Analysis And Application Of Lonworks Bus

With the development of the fieldbus technology, there are more and more communication protocols, nowadays, communication protocols can't be unified, and will coexist for a long time. So it is general trend that improving real-time performance to enhance the station of each fieldbus and widen their application area.Firstly, starting with the MAC (Media Access Control) protocol of the Lonworks bus and according to collision resolved and collision avoidance, relative improved schemes are presented after analyzing the hard and soft real-time performance of LonTalk protocol. Considering soft real-time, conclusion is drawn that unacknowledged service can only be used. It can't satisfy soft real-time requirement because the collision probability is high. So a way of analyzing and improving the backoff scheme is adopted, the parameter of which is dynamically estimated, so the result indicates that collision probability is reduced by the enhanced backoff scheme, especially under heavy traffic load it can get a higher throughput. Under hard real-time environment, a new LonTalk protocol is given to improve arbitration architecture and its maximum response time and fastest response time were endued. It reduces the bandwidth waste effectively comparing with the TDMA scheme when the load is light, and comparing with the hard real-time improved scheme presented by Alexander Bauer, the maximum response time of improved arbitration architecture becomes shorter.The thesis details the application of Lonworks bus on the terrestrial-heat heating system, and the network structure is described. What's more, the field-layer temperature gathering nodes are designed. At last, the control and supervision are realized by the LiKong software and DDE technology.