A system having a sensor using one or more magnetic field detectors to determine its position on a path of travel relative to one or more magnets situated on the path. The magnets may be electromagnets arranged in regions along the path with a region between two electromagnets. One or more electromagnets may be selectively activated so as to define a region where the sensor is present. An indication from the system may provide a position of the sensor within a region and identify the region where the sensor is situated.