文档介绍：LonWorks总线实时通信协议的研究
摘要:从LonWorks总线的介质访问机制入手,本着冲突避免和冲突解决两个原则,论证了LonTalk协议在实时性方面存在的问题。对LonTalk协议的MAC仲裁机制进行了改进,提出了一种新的实时通信协议,解决了因较高优先级节点交替占用总线而使较低优先级节点长期得不到总线使用权的问题。实验结果表明,与原协议相比,新的实时通信协议在网络节点数大于10时,%以上,网络有效利用率提高了100%。新的实时通信协议在实时性、确定性等方面均优于原协议。
关键词:LonWorks总线;实时性;LonTalk协议;MAC机制
Study on the real munication protocol of LonWorks bus
Abstract:Starting from the media access control mechanism of the LonWorks bus and based on the principle of collision avoidance and collision resolution, the problem of real time property in the LonTalk protocol is proved, and the MAC arbitration mechanism of LonTalk protocol is improved. A new real munication protocol is proposed, which resolves the problem that low priority nodes can not obtain bus access authority over a long period of time, because the bus is occupied alternatively by high priority nodes. Experiments show pared with the previous protocol, when the number work nodes are more than 10, the new real munication protocol reduces the maximum delay time of message transmission at least by % and work utilization efficiency is enhanced by 100%. The new real munication protocol is superior to the previous protocol in real time property and confirmation.
Key words:LonWorks bus; real-time property; LonTalk protocol; MAC mechanism
1 引言
现场总线技术彻底改变了传统控制系统的体系结构,是一种典型的实时分布式控制网络技术。现场总线为底层控制网络,它不同于普通数据网络的最大特点在于,它必须满足对现场控制的