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Converging Information Technology (IT) and Operations Technology (OT) in modern factories remains a challenging task. Several approaches such as Cloud, Fog or Edge computing aim to provide possible solutions for bridging OT that requires strict real-time processing with IT that targets computing functionality. In this context, this paper contributes to ongoing Fog computing research by presenting three industrial use cases with a specific focus on consolidation of functionality. Each use case exemplifies scenarios on how to use the computational resources closer to the edge of the network provided by a Fog Computing Platform (FCP). All use-cases utilize the same proposed FCP, which allows drawing a set of requirements on future FCPs, e.g. hardware, virtualization, security, communication and resource management. The central element of the FCP is the Fog Node (FN), built upon commercial off-the-shelf (COTS) multicore processors (MCPs) and virtualization support. Resource management tools, advanced security features and state of the art communication protocols complete the FCP. The paper concludes by outlining future research challenges by comparing the proposed FCP with the identified requirements.

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Worst-case execution time (WCET) analysis is a prevalent way to ensure the timely execution of programs in timecritical systems. With the advent of new technologies such as fog computing and time-sensitive networking (TSN), the interest in timing analysis has increased in industrial communication. This paper highlights experiences made while adjusting the publisher of the open62541 OPC UA stack to enable WCET analysis, following a simple process combined with the open-source platform T-CREST. The main challenges are the required knowledge about the code and the specific communication software characteristics like variable message sizes. Other findings indicate the need for other types of annotation for indirect recursion or callback functions. The paper provides the foundation for further research on adjusting the implementation of existing industrial communication protocols for WCET analysis.