Characterization of electrical rotary distributors for real-time data communication

In modern connected factories, network access has typically to be provided to all the devices involved with the industrial control applications. If rotating parts of an industrial machinery are involved, a practical and widespread solution to ensure signal continuity with the fixed section is the use of Electrical Rotary Distributors (ERDs). In their general structure, these electro-mechanical devices exploit sliding contacts over conducting rings to propagate the signals. Such implementation requires adequate care, in particular when ERDs are used to convey high bandwidth signals, such as those typical of Real Time Ethernet (RTE) networks, that are communication systems widely deployed in factory automation. In this framework, this work actually considers a specific ERD that showed communication impairments when deployed to implement a link of a RTE network and carefully investigates the root causes of this behavior. To this aim, a specific test procedure has been implemented, and a measurement campaign has been executed. The relevant outcomes actually highlight that the communication performance losses are due to a problematic ERD design. The analysis carried out allowed to propose a possible solution to this issue and, more importantly, to design a measurement system suitable for the prototyping of ERDs for real-time communication.