Abstract: The invention relates to a device for monitoring a yarn (1), which is moving in its longitudinal direction, using a measuring head and an evaluation unit (7) which is spatially separate from and connected to the measuring head. To enable optimum use of measuring heads operating according to different physical principles without unduly increasing the outlay, the measuring head includes a first part (2) operating according to a first measuring principle and having a connection (5) to a first part (6) of the evaluation unit for making an evaluation according to the first measuring principle. The measuring head then comprises a further part (9) operating according to a further measuring principle and having a releasable connection (8, 10) to the first part. In addition, the evaluation unit likewise comprises a further part connected by a releasable connection for the evaluation according to the further measuring principle.

Abstract: A number of sensors, each including a light source, illuminating and imaging optics and a detector, are arranged decentrally on a spinning or winding machine having a number of thread lines to provide online monitoring of the winding quality of a number of bobbins during the production of the bobbins. The sensors are preferably mounted on bobbin changers to traverse back and forth across a plurality of thread lines to examine a plurality of bobbins as they are being wound. These sensors are used on spinning or winding machines equipped with an electronic yarn-clearing system, with an interlinking of the measurement signals.