The MNU Series ultrasonic liquid-level sensors from Automation Products Group, Inc. operate as slave devices. They are self-contained sensors that measure distance, level, or volume via a standard Modbus RTU protocol (RS-485) output. Available in sensing ranges from 4 in. to 40 ft., accuracy is specified as ±0.25% of detected range and with a resolution of 0.1 in. or 2.5 mm. Other features include a low current draw, making the MNU components suitable for use in remote locations where power conservation is critical.