Abstract: A precise, accurate and sensitive control method and system for actuating the stop motion mechanism of a weaving loom equipped with a weft yarn storage feeder unit is disclosed. The storage and feeder unit includes a device for applying tension to the weft yarn being delivered from a weft yarn supply to the storage and feeder device. The tension device is equipped with a switch which provides a first electrical signal when the weft yarn being supplied to the storage and feeder device becomes slack or interrupted. That switch is connected with the weft yarn storage and feeder unit motor circuit. The weft yarn storage and feeder unit may be intermittently driven as the need occurs for feeding a weft yarn length or pick into the loom.