On computing and real-time communication performance of containerized virtual PLCs

The Industry 4.0 has led to a significant transformation in manufacturing and industrial processes, characterized by increased connectivity and widespread digitalization. This revolution is driven by the convergence of IT (Information Technology) paradigms with OT (Operational Technology) domains. Virtualization technology plays a crucial role in this integration, thanks to its characteristics of agility, scalability, and efficiency. This work investigates the virtualization of Programmable Logic Controllers (PLCs) and it is focused on the need for evaluating their performance. PLCs are essential components of industrial automation and are being virtualized to increase flexibility, reduce hardware dependencies, and enable seamless integration with IT infrastructures. This work proposes a methodology for evaluating the execution time of a benchmark program and the PLC real-time behavior. Experiments on a real use case demonstrate that the PLCs implemented in containers may be 50 times faster than the real ones in executing data elaboration, while no significant differences were observed in real-time communication. In any case, virtual PLCs are characterized by greater jitter with respect to real PLCs.