Ultrasonic sensors employ a special sonic transducer, which allows for alternate transmission and reception of sound waves. The transducer emits a series of sonic pulses and then "listens" for their return as they are reflected from the target. Once the reflected signal is received, the ultrasonic sensor signals an output to a control device such as a PLC. Ultrasonic sensors are capable of reliably detecting targets such as solids, liquids, granules or powders irrespective of color and opacity at sensing ranges up to 2.5 meters. While standard diffuse units will give simple presence/absence of target information, some units can produce analog outputs that offer actual distance measuring. This ultrasonic senor output can easily be converted into useable distance information for continuous level detection.