An intravenous coupling apparatus is disclosed for fluid delivery to a patient. The amplifier herein receives a reference voltage and outputs a regulating voltage. A scanning device deflects the fixation light to produce a fixation pattern of the fixation light on the eye, and deflects the procedure light to produce a procedure pattern of the procedure light on the eye. The present technology can support a high number of concurrent continuous queries using a scalable and efficient shared query evaluation scheme, support on-the-fly addition of continuous queries into a mechanism that implements the shared evaluation scheme, reuse RDBMS modules such as relational operators and expression evaluators, and visualize results of continuous queries in real time. The method includes: generating a control physical layer preamble; generating a header, wherein the header includes a mode indicator; modulating and encoding a payload according to the mode indicator; generating a packet according to the control physical layer preamble, the header and the payload; and transmitting the packet. Based on the trouble state detection result, a driving operation of a main motor is varied, and a notice of the trouble state of the printer engine is issued, thereby easily discriminating trouble contents by using only the printer engine without any personal computer or another specific jig, etc.