【作者】 胡文山；

【导师】 周洪；

【作者基本信息】 武汉大学 ， 控制理论与控制工程， 2004， 硕士

【摘要】 以太网技术是建立在CSMA/CD这样的非确定网络协议基础之上的,它的优点是可以实现很大的吞吐量,并且软硬件设备非常廉价。然而,在需要实时应用的工业领域,网络传输的确定性变成了重要的因素,传统以太网协议就变的难以胜任了。 为了将以太网从商用领域移植到工业领域,建立工业以太网,必须用实时的网络协议来替换不确定的商用以太网协议。因此,基于DSP技术,本文设计了一套新的工业以太网体系来保证数据传输的实时性。在这套体系中,本文引入了网络枢纽控制器这个设备。它作为网络的中枢控制设备,控制着整个网络的运行,其他网络设备必须在它的控制下收发送数据。 在所设计的工业控制网络体系中,所有的数据被分为三个优先级,第一优先级的数据为控制信号,它们必须在规定的时间内送达;第二优先级的数据为多媒体数据;第三优先级的数据为一些重要性和实时性都较低的数据,它们的可靠性主要靠上层协议保证。当网络负荷超载时,网络枢纽控制器就会通过丢弃一些低优先级的数据,来保证高优先级数据的实时性。 本文介绍了具体的工业以太网控制器的网络控制算法;为了证明这套算法的可行性,作者还对这套算法建立了数学模型,进行了计算机仿真,并进一步分析了仿真结果;在以上的基础上,作者开发了系统的关键设备。 文本还对网络枢纽控制器和一些网络设备的软硬件设计进行了介绍。 以上诸研究结果表明,本文所提出的工业控制网络体系是切实可行的,具有十分广阔的应用前景。更多还原

【Abstract】 The Ethernet technology is based on the non-deterministic protocols such as CSMA/CD, which can performance well on office environment due to their big throughput and cheap price. But in the real time application of industrial environment, the deterministic behaviors become the most important issue which can not be satisfied by these protocols. It is difficult to build a real time control network using standard Ethernet, because its MAC protocol is based on CSMA/CD. The transport of a packet from one node to another node may experience a large delay which is unable to be predicted.Therefore, in order to achieve transplant from the office Ethernet to industrial Ethernet, we must replace the non-deterministic Ethernet protocols by deterministic protocols. We build a new kind of Ethernet which can guarantee the real time application under the office Ethernet media. A device called Central Network Control Unit is introduced in the thesis, which is the central control unit of the network and is used to arbitrate the usage of network media. All other devices in the network must work under its control. They can only send packets when it orders them to do so.The packets are divided into three priorities duo to their importance. The first priority packets are the control packets which must be sent to the destinations in a certain time. The second priority packets are the multimedia packets. The third priority packets are other less important packets which have no real time requires and whose reliabilities can be achieved by upper level protocols. When the network is overloading, the Central Network Control Unit can perceive it and dropout some low priorities fluent to keep the real time behavior of high priorities fluent.The details of the network control rules are introduced in the thesis and the computer emulations are provide to prove the feasibility of these rules.The designs of the Central Network Control and some devices under the control of it are also introduced by the author.更多还原