Static Timing Analysis of OPC UA PubSub

Industrial automation is changing towards higher integration and seamless communication. A stepping stone is end-to-end real-time machine-to-machine communication, now becoming feasible with technologies such as time-sensitive networking (TSN) and OPC Unified Architecture (OPC UA) publish-subscribe. While TSN takes care of communication, the OPC UA stack's execution time behavior remains unknown. This paper highlights experiences made while adjusting the OPC UA subscriber of the open62541 stack for worst-case execution time (WCET) analysis. Two directly connected time-predictable T-CREST platforms hosting the publisher and subscriber delivered end-to-end timing measures validating the WCET estimates. The paper concludes by outlining further research with several time-predictable publishers and subscribers.