Evaluating TSN Preemption for Cyclic EtherNet/IP Communication

Technical Paper Abstract
Industrial Control systems use Ethernet-based protocols such as EtherNet/IP and Modbus TCP for cyclic communication to exchange process data, such as inputs, outputs, and motion commands and feedback. One limitation of Ethernet is its lack of determinism. For certain applications, like motion control, this has led to the development of protocols like SERCOS and EtherCAT, which rely on specialized hardware solutions.

Recently, Ethernet specifications have evolved to include time Sensitive Networking (TSN) which defines features like a Time Aware Shaper (TAS) to achieve predictable transport of Ethernet messages. However, not all cyclic communication used in industrial control systems need the determinism offered by TAS but do require a bounded message latency. TSN defines a feature called preemption that can address this use case.

This paper will provide an overview of TSN preemption and will analyze its use in Ethernet-based industrial control communication. A simulator, written in the Python programming language, is defined, allowing for analysis of varying topologies and cyclic rates. Interfering traffic is introduced to demonstrate the effectiveness of preemption to limit the disturbances.

Paper and presentation from the 2022 ODVA Industry Conference & 21st Annual Meeting

Rick Blair. Schneider Electric