Survey on real-time communication via ethernet in industrial automation environments

For companies in the automation industry, the development of real-time Ethernet to connect devices is of high economic interest to replace conventional fieldbus systems. Therefore, many approaches for adapting Ethernet to real-time requirements come from industrial applications. This is a challenging task as the original Ethernet standard IEEE 802.3 was not designed for real-time data transmission. Likewise, protocols basing on Ethernet like TCP, UDP, and IP do typically not consider real-time requirements. Hence, adaptations on several OSI layers become necessary to make the industrial system meet hard real-time requirements. For this purpose, a multitude of realtime capable Industrial Ethernet systems has been developed, which solve the problems of standard Ethernet- and TCP/IP- or UDP/IP-based communication in a variety of ways. This paper gives a summary of different Industrial Ethernet protocols for the real-time data transmission via Ethernet in automation environments. Advantages and disadvantages of these protocols are analyzed with regard to their sustainability in terms of their realtime capability, reliability, scalability, self-configuration of the network, and hardware requirements. Against the background of connected devices tremendously growing in number and computational power in the prospective “Industrial Internet”, consequences for future developments are drawn.