Abstract: In this study, a design is proposed based on the cross-platform Modbus library Libmodbus’ navigational sea surface temperature monitoring system to address the current situation in which the sea surface water temperature observations are mainly conducted via manual processes. In this design, the sensors located under the waterline toward the side of the ship are used to obtain the surface water temperature. The RS485/Modbus protocol is adopted to implement a multistation multipoint network to obtain a distributed system for automatically obtaining the sea surface temperature. The host computer is based on the Modbus-RTU protocol and involves cyclic redundancy check to ensure remote control of the water temperature sensor and the reliability as well as safety of the surface water temperature collection function. The designed system is not only stable, simple, and easy to operate but also portable and scalable. The experimental results show that the designed system can monitor the sea surface temperature in a stable and reliable manner and realize online measurement of the surface water temperature with respect to a ship.

Key words: water temperature sensor, sea surface water temperature, Modbus-RTU protocol, RS485 bus