The basic working principle of RFID technology is not complicated: after the tag enters the reader, it receives the RF signal sent by the reader and uses the energy obtained by the induced current to send out the product information stored in the chip (passive tag, passive tag or passive tag ), Or the tag actively sends a signal of a certain frequency (Active Tag, active tag or active tag), after the reader reads the information and decodes it, it sends it to the central information system for related data processing.
A complete RFID system is composed of a reader, an electronic tag, a so-called transponder, and an application software system. Its working principle is that the reader emits radiofrequency energy of a specific frequency for The drive circuit sends out the internal data. At this time, the Reader receives the decoded data in order and sends it to the application for corresponding processing. 
From the perspective of communication and energy-sensing methods between RFID card readers and electronic tags, it can be roughly divided into two types: inductive coupling and backscatter coupling. Generally, the low-frequency RFID mostly adopts the first method, and the higher frequency mostly adopts the second method.
Depending on the structure and technology used, the reader can be a reading or reading/writing device and is an RFID system information control and processing center. The reader usually consists of a coupling module, a transceiver module, a control module, and an interface unit. The reader and the tag generally use half-duplex communication to exchange information. At the same time, the reader provides energy and timing to the passive tag through a coupling. In practical applications, management functions such as collection, processing, and remote transmission of object identification information can be further realized through Ethernet or WLAN.