On the Ethernet use for real-time publish-subscribe based applications

Ethernet is very attractive for the automation area due to its availability and low implementation cost. Due to its media access control (CSMA/CD), Ethernet is not deterministic in general and its behaviour under transient overload is not sufficient for any real-time application. On the other hand, if the applications have predictable and bounded number of requests, behaviour of Ethernet is "nearly" real-time (very low probability of delayed data delivery). This article tests ORTE (open real-time Ethernet), an open-source implementation of RTPS middleware (real-time publish-subscribe), built upon UDP/IP and tested on Ethernet. This middleware can be used in real-time control applications, which typically have limited and relatively small input load compared to the high bandwidth. To derive the influence of the operating system, we combined the application response time measurement with the simulation.