Bidirectional immersive digital twin for real-time monitoring and supervisory interaction in PLC-controlled manufacturing

Digital Twins are increasingly used for monitoring and interaction with automated processes, but integrating immersive environments with active control systems while preserving controller authority remains challenging. This study presents an operational and supervisory immersive Digital Twin for a PLC-controlled automated filling process, enabling bidirectional communication between a physical module and its virtual representation. The architecture integrates a Siemens S7-1200 PLC, OPC UA, MQTT, and a virtual reality environment. PLC-reported process states are mapped to corresponding virtual components, while supervisory commands generated in the virtual environment are returned to the PLC and processed by its control logic before affecting the physical module. Experimental validation was conducted on a laboratory-scale automated bottling module over 100 operating cycles. Process-update latency averaged 78 ms, ranging from 64 to 92 ms, with a system availability of 99.4%. Evaluation of 100 supervisory commands yielded mean command transmission, controlled-process response, and end-to-end round-trip times of 42, 180, and 302 ms, respectively, with a command success rate of 99.0%. An interaction study with 26 participants showed comparable task completion times for WinCC and the immersive Digital Twin, with fewer operational errors, lower NASA–TLX scores, and a System Usability Scale score of 94/100. The results confirm bidirectional supervisory interaction and support physical–digital state correspondence during experimental operation while maintaining PLC control authority.