An analysis of OPC UA communication with CNC turning machines: emphasis on synchronized data acquisition

Abstract. This paper delves into the operational efficacy of the OPC UA communication protocol in tandem with CNC machines. An OPC UA client, embedded within Node-Red, was devised to establish seamless communication with a CNC turning machine. A primary facet of our investigation centered on the protocol's performance during simultaneous multi-client interactions, with each client sending multiple queries—a scenario termed as "multi-client overlapping". Our analysis underscores the intricacies of the prioritization criteria employed to streamline queries. Findings indicate that queries from a single client aren't processed consecutively, leading to unsynchronized value retrievals. Comparative experiments, conducted directly between clients and server and via an intermediary switch, highlighted the marked advantages of the latter approach. Leveraging a switch bolstered the prioritization of queries, enhancing reliability. In essence, this research underscores the pivotal role of synchronized data acquisition in optimizing communication efficacy.