Distributed control systems are currently evolving towards industrial Internet of Things (IoT) systems communicating fully using Internet protocols. This creates opportunities for streamlining costly commissioning processes, which today require substantial manual work for installing, configuring, and integrating thousands of actuators and sensors. The vision of "plug-and-produce" control systems has been pursued for more than 15 years, but existing approaches fell short regarding configuration tasks and vendor neutrality. This paper introduces the standards-based IoT reference architecture OpenPnP, which allows largely automating the configuration and integration tasks of industrial commissioning processes. The architecture includes a number of design and technology decisions and the required implementation can be scaled down to resource-constrained industrial devices. This paper demonstrates how OpenPnP can reduce configuration and integration efforts up to 90% in typical settings, while potentially scaling well up to tens of thousands of communicated signals. Practitioners can orient their implementations towards OpenPnP, therefore potentially enabling "plug-and-produce" in many thousands of control systems. KEYWORDS client-server systems, control engineering, Internet of Things, real-time systems, software architecture 246 of these tasks include a number of manually executed steps done by engineers, for example, the device identification, device wiring, entering configuration parameters, and interaction fine-tuning between devices, the control system, and workstations. Many of these tasks are even more complicated due to the lack of standardized parameter models, legacy communication interfaces, and proprietary software tools requiring profound knowledge and expertise. Hence, the entire process of commissioning a plant or a process including thousands or ten thousands of devices may last several calendar months, costing millions of dollars. [3][4][5] Taking this into account, there is a high interest from customer side to simplify the commissioning process. 6 Therefore, researchers and practitioners have been working on "plug and produce" (PnP) approaches in the last two decades. 7,8 They simplify the process for commissioning a device in process automation similar to the installation and usage of devices for consumer computers, so called "plug and play." Transferring this concept to the process automation world is complicated because such an PnP approach needs to be implemented on different levels in operation, starting from device level up to plant or even enterprise level. Existing proposals for PnP approaches 9-13 often focus on low-level network discovery of industrial field devices but neglect higher-level configuration and integration tasks, which cause most manual efforts. Especially, for PnP on the device level, network discovery of industrial field devices is only one task of many. The industrial field devices also need standardized and self-describing information models so that no additional informa...
