Abstract

The Programmable-logical-controller (PLC) has been the key building block of industrial control systems throughout the whole automation revolution, where its role has been mainly to command low-level regulatory feedback control loops. Despite the great recent advances in automation technologies, driven by the paradigm of the Industry 4.0 and its hyper-connected ecosystem, the PLC has not seen yet a modernized version targeting the functionalities an Industry 4.0-oriented control system requires. In this work, a device named IoT-PLC is designed and prototyped, in an effort to generate a PLC tailored for the Industry 4.0 revolution. The proposed IoT-PLC operates as a containerized piece of equipment, with each functionality packaged within a separate container. The IoT-PLC has regulatory control capabilities, fog-computing functionalities as filtering and field data storage, and multiple wireless interfaces managed independently. Moreover, it uses a virtual device model that works as an abstraction method to represent real entities, so that IoT-PLC applications can interact transparently and with straightforward compatibility with upper cloud layers. Live migration functionalities add flexibility by allowing a loop reconfiguration without restarting the controller. Laboratory experiments illustrate the effectiveness and potential of the proposed device.