浅析Profibus网络的FDL

Analysis of Profibus FDL

对Profibus的令牌传递与主从结合的访问机制进行了详细分析;由帧格式分析了FDL的编码效率与有效数据传输率;给出并研究了ProfibusFDL获得令牌后报文调度的四种模式调度流程;对调度模式中涉及TTR、TRR、TTH三个参数研究了它们之间的关系,这三个参数影响着报文的调度与实时应用。

The token passing access mechanism, which is combined with master-slave, are analyzed. Encoding efficiency and effective data transmission rate of FDL are calculated according the frame format of FDL. Four scheduling profiles are given, which individually called immediate unconstrained low-priority traffic profile, immediate constrained low-priority traffic profile, unimmediate unconstrained low-priority traffic profile, unimmediate constrained low-priority traffic profile, are researched to give their message handling flow diagrams. Based on several time conceptions, the relations of TIR, TRR and TTH, which impact on message scheduling and real time application, are presented.