Modbus-OPC UA Wrapper Using Node-RED and IoT-2040 with Application in the Water Industry

In the context of connecting the physical and the digital worlds, common grounds must be established in several areas. Industry 4.0, Industrial Internet of Things (IIoT) principles are focused on interoperability. Regarding the interfacing, the OPC UA (OPC Unified Architecture) protocol is considered to be the most important. Descending from the PC based supervisory levels to the automation level (automation panels, machine and sensorial levels), achieving OPC UA interfacing is harder. Legacy systems, specific protocols, the need of lower cost hardware/software middleware equipment for existing systems that supports the industrial environment, flexibility to augment the existing structure with additional software modules, to develop easy knowledge transfer for integrators with lower software skills, are representing current issues on the automation level. Considering that a large part of the existing automation structures is using Modbus protocol, especially serial Modbus, the paper proposes a Modbus-OPC UA wrapper, considering a middleware IoT 2040 hardware equipment and Node-RED software environment, in order to provide interoperability. The work focuses on the serial Modbus client interface, but it can be extended within the same proposed structure to other protocols. The concept is tested first in the laboratory and then in a real scenario consisting of an existing wastewater pumping station (WWPS).