Abstract: Various embodiments disclose a method for operating a printer apparatus that includes a print head. The method includes causing a media hub to retract a media in a retract direction along a media path. Further, the method includes causing a first media sensor to generate a first signal during retraction of the media. Furthermore, the method includes monitoring the first signal to detect at least one of a leading edge or a trailing edge of a label of the plurality of labels. Upon detecting the at least one of the leading edge or the trailing edge of the label, causing the media hub to retract the media by at least a predetermined distance, wherein the predetermined distance is a distance between the print head and the first media sensor.

Abstract: Disclosed is a sensor network for reporting based on the trigger of an event library, comprising a network and a monitoring terminal. The monitoring terminal is provided with a sensor unit, a data processing unit, a communication unit and a power source, wherein the sensor unit is connected to the data processing unit and is used for sending the data collected by the sensor unit to the data processing unit; the data processing unit communicates with the network through the communication unit; and the power source is used for supplying power.