Abstract: A new signaling propagation mechanism based on carrier length sensing is described in this paper, where after a new real time Ethernet medium access control protocol generated. By making use of message length to carry priority information and blocking the access right of the low priority in the event of collision, the new protocol provides the bounded transmission delay for hard real time messages over the standard Ethernet bus. OPNET simulator is utilized to show the implementation method, and the new protocol is modeled as a finite state machine (FSM) in detail. The simulation results demonstrate the protocol’s correctness and effectiveness.

Key words: industrial Ethernet, medium access control, protocol modeling

摘要： 介绍了一种基于载波长度的信令传播机制，根据信元的包长建立优先级，新型的实时以太网介质访问控制协议通过引入信道阻塞模式，在标准以太网信道上为硬实时信息提供具有上限的传输时延保证。在OPNET仿真环境下，详细描述了用离散时间驱动的有限状态机实现协议的建模方法，并通过仿真验证了协议的正确性和有效性。

关键词: 工业以太网, 介质访问控制, 协议建模