Assessment of Different OPC UA Implementations for Industrial IoT-Based Measurement Applications

The industrial Internet of Things (IIoT) paradigm represents an attractive opportunity for new generation measurement applications, which are increasingly based on efficient and reliable communication systems to allow the extensive availability of continuous data from instruments and/or sensors, thus enabling real-time measurement analysis. Nevertheless, different communication systems and heterogeneous sensors and acquisition systems may be found in an IIoT-enabled measurement application, so that solutions need to be defined to tackle the issue of seamless, effective, and low-latency interoperability. A significant and appropriate solution is the open platform communications (OPCs) unified architecture (UA) protocol, thanks to its object-oriented structure that allows a complete contextualization of the information. The intrinsic complexity of OPC UA, however, imposes meaningful performance assessment to evaluate its suitability in the aforementioned context. To this aim, this article presents the design of a general yet accurate and reproducible measurement setup that will be exploited to assess the performance of the main open-source implementations of OPC UA. The final goal of this work is to provide a characterization of the impact of this protocol stack in an IIoT-enabled measurement system, in particular, in terms of both the latency introduced in the measurement process and the power consumption.