An operative device
For scanning or interrogating the individual measuring heads M1 to Mn a clock pulse generator CL supplies pulses at a high repetition frequency in the range of several kHz like, for example, 10 Hz. The mode of operation of the electronic scanner or interrogation system described heretofore will now be explained withreference to FIGS. An operative device containing a switching stage SS which, in the case of thread rupture turns-off either the textile machine or just the related thread running location, is connected to the signalling negative scanner or indicator line A. Furthermore, a third AND-gate or circuit A3including a negated first input connected to a respective one of the thread running locations, and a series of bistable controllers F1 and Fn, respectively. A second AND-gate or circuit A2 including a negated first input 66 and a further bistable controller F7 having a negated output Q connected in series thereto form an initiating or start circuit.