在这种情况下，带模拟量输出的超声波传感器从下方检测材料的下垂度。并且通过下垂度的变化及时调整材料的进料速度。当下垂的材料环向一侧摆动时，如果从上方检测，声波很容易就发生偏转，所以这种情况就必须从下方检测材料环，如左图所示。
Depending on the width of the web material and the measurement range, two sensor families with different housing designs are available:
- mic+ with M30 threaded sleeve: Measuring range of 350 mm or 1,300 mm
- lcs with cubic housing: Measuring range of 350 mm or 1,300 mm
