Turning old into new: adding LoRaWAN connectivity to PLC in brownfield installations

Industry 4.0 paradigm improves industrial automation systems efficiency leveraging on the Industrial Internet of Things (IIoT), offering pervasive connectivity with field devices and paving the way to innovative services. Updating legacy machines in brownfield installations is needed for preserving investments. This paper discusses the design and the experimental validation in a real-world use case of a low-cost solution aiming at providing LoRaWAN Class A connectivity to a Programmable Logic Controller (PLC). Widespread modules, offering full compatibility with the standard, are considered. They behave as “modems” controlled by AT-like commands via simple serial links (RS232), minimizing the need for additional glue logic. The developed solution has been connected to a public LoRaWAN infrastructure, showing average uplink delays in the order of 300–500 ms; on the contrary, downlink messages are constrained by uplink interarrival time. The experiments also highlighted strong correlation between the LoRaWAN network congestion and the end-to-end delay.