Multilayer feed of materials such as paper, cardboard, metal, film or labels can lead to downtimes, process disruptions, and even material waste. Ultrasonic sensors for double sheet detection prevent a faulty material feed and ensure reliable processing and high availability. Combined with IO-Link, the user has full access to sensor parameters, and diagnostic and process data. The IO-Link interface enables comprehensive communication as well as simple commissioning and parameterization, while threshold values can be individually set via teach-in function.