The radio wave is used to complete the read and write operations between the non-contact and the card reader
. The communication frequency between the two is 13.56MHZ. The non-contact nature itself is a passive card. When the reader reads and writes to the card, the signal sent by the reader is composed of two parts: one is the power signal, which is received by the card, and its own L/ C generates an instantaneous energy to supply the chip to work. The other part is the instruction and data signal, which instructs the chip to complete data reading, modification, storage, etc., and returns the signal to the reader to complete a read and write operation. The reader is generally composed of a single-chip microcomputer, a dedicated smart module and an antenna, and is equipped with a communication interface with a PC, printing port, I/O port, etc., so as to be used in different fields.