Hosting functional safety applications in factory networks through Time-Sensitive Networking

Transmitting time-critical data like safety applications over the traditionally not real-time capable Ethernet standard (IEEE 802.1) requires modifications. Compared to devices, individually connected by signal wires, "network-attached" safety components offer more flexibility in their usage by making their data available to all factory entities instead of just one counter partner.openSAFETY – open-source standard for safety-related applications – enables functional safety, that can be integrated in any network with deterministic behavior. Time-Sensitive Networking (TSN) – a set of IEEE standards that can be applied to IEEE 802 networks – offers the possibility to run Ethernet traffic with real-time requirements without the traditional problems of Ethernet like frame dropping or timing issues.This paper proofs the concept of these two technologies being a suitable combination to transmit time-critical safety data and non-priority traffic within a single Ethernet-based network. Several tests were made to show how TSN can host an openSAFETY-application in different scenarios including background traffic. The results show adequate performance of this system in terms of reliability under worst possible conditions like external broadcast traffic blocking the entire bandwidth.