Waddington Electronics Inc., Cranston, R.I., says its SONA-trOL® ST-6 Ultrasonic Loop Controller
measures true diameters during unwinding and rewinding, providing non-contact tension control and
ensuring smooth converting operations.The device features a sensor head that can be mounted from 18
inches to 20 feet above a roll of material. It measures distance changes as small as 0.01 inch. Up
to 100 loop measurements per second are performed, and an alarm sounds if seven consecutive
measurements per second do not conform to present limits.The SONA-trOL ST-6 is designed to be
controlled externally using a programmable logic controller (PLC) or computer. Other features
include adjustable distance zero offset, receiver sensitivity and gain.