microIoTSCADA: A Tool to Monitor and Control Renewable Energy-Based Systems Using MODBUS

The telecommunication protocol MODBUS TCP is an open industrial standard widely used for control and monitoring. It is based on the polling communication mechanism, which means that the client polls the server for measurements from sensors and controls connected devices via set points. The polling-based mechanism follows the synchronous request-and-response pattern. However, the simple mail transfer protocol (SMTP) is an example of message-oriented protocol. Hence, the standard is employed in this paper for email-based notifications of measurement values formatted in JavaScript object notation (JSON) for interoperability. While the former uses byte-oriented application messages to exchange data between communicating devices, the latter uses information-oriented messages between communicating people. This study investigates the collaboration between both protocols to realize a control and monitoring Internet of Things (IoT) scenario in environments fed by renewable energy sources (RESs). Nevertheless, MODBUS specifications do not specify a way to represent floating-point values; the standard IEEE 754 is employed here. The tool is applied to a water pump fed by a RES. However, the proposed tool can also be used to control and monitor systems fed by RESs, smart homes, and educational purposes. Moreover, it can be modified and adapted to monitor industrial production lines.