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评估一个网络控制器的性能,通常都只会注意到它本身具备了哪些功能,在一个通讯系统中它能实现哪些特殊的功能。我们很少会注意到,当该网络控制器与高速CPU数据接口相连时,传输批量数据所遇到的数据传输“瓶颈”问题,特别是对于实时性能要求特别苛刻的实时工业以太网系统。与传统的现场总线系统相比,实时以太网系统的循环周期要求更小,传输的报文长度也要求更长。另外,对于同步需求和时间抖动,其精度要小于10纳秒。如果还延续过去常使用的双端口内存DPM主机接口访问方式,显然已经不能满足其性能需求了。在接下去的文章中,将讲述如何选用灵活多样的netX控制器接口来满足不同的工业通讯系统的不同需求。
Assessing the performance of a network controller usually only notices what features it has and what special features it can implement in a communications system. It is seldom noted that the problem of data transfer “bulk bottleneck” encountered when transferring the bulk data when the network controller is connected to the high-speed CPU data interface is particularly problematic for real-time Industrial Ethernet systems that require particularly demanding real-time performance . Compared with the traditional field bus system, real-time Ethernet system cycle requirements smaller, the length of the message transmission also requires more. In addition, for synchronization requirements and time jitter, the accuracy is less than 10 nanoseconds. If you also continued in the past often used dual-port memory DPM host interface access, apparently can not meet its performance needs. In the following article, you will learn how to choose a flexible netX controller interface to meet the different needs of different industrial communication systems.