Digital four-electrode digital conductivity and salinity sensor is designed for reliable, continuous water quality monitoring in aquaculture, seawater systems, rivers, wastewater treatment facilities, and environmental engineering applications. Equipped with a dedicated four-pole alloy electrode, it minimizes polarization effects and provides stable, accurate measurements over a wide conductivity range of 0–500 mS/cm while simultaneously determining salinity levels in aqueous solutions. The sensor is built for long-term deployment in demanding environments and features a standard RS485 interface with Modbus RTU protocol, allowing seamless integration with PLCs, SCADA systems, data loggers, telemetry units, and IoT platforms for remote monitoring, data acquisition, and process control. Its robust construction, wide measurement range, and low maintenance requirements make it an ideal solution for professional water quality monitoring applications.