基于有色Petri网的TII协议建模与分析

TII Protocol Modeling and Analysis Based on Colored Petri Network

变送器独立接口(TII)协议有不同的应用方法且存在实施差异,需要对其进行建模、分析和验证.文中针对不同通道类型,建立层次化的TII协议有色Petri网(CPN)模型;采用数据传输平均延时、通道利用率、数据传输速率、数据帧丢失率作为性能评价指标,借助CPN Tools仿真软件对模型进行了性能分析;讨论了接口速率、采样速率比、采样数据长度、缓存队列长度等接口参数对性能指标的影响,提出了可控连续采样、增加通道数据长度、虚拟多通道、后进先出缓存及先进先出丢包等提高模型性能的方法与措施.该模型的实际应用表明,当STIM的通道类型为带缓存数据序列型时,数据帧丢失率为0,数据传输速率为1500B/s,数据传输平均延时为0.21ms.

For TII（Transducer Independent Interface） protocol,there are different application methods and implementations,which need to be modeled,analyzed and verified.In this paper,first,according to different channel types,a hierarchical CPN（Colored Petri Net） model of TII protocol is established.Then,by using the average delay of data transmission,the channel utilization,the data transfer rate and the loss rate of data frames as perfor-mance evaluation indexes,the performances of the model are analyzed with the help of CPN Tools.Moreover,the performance indexes,which are affected by such interface parameters as interface rate,sampling rate ratio,sampling data length and buffer queue length,are discussed,and several methods and measures are proposed to improve model performances,such as increasing the channel data length and adopting controllable continuous sampling,virtual multi-channel,last-in-first-out buffer and first-in-first-out packet loss.Application results of the proposed model show that,when STIM channel is BDS（Buffered Data Sequence）,the loss rate of data frames,the data transfer rate and the average delay of data transmission are 0,1500B/s and 0.21ms,respectively.