JMY604 series are RFID reader/writer module with RS232C serial ports. JMY604 has various functions and supports multi ISO/IEC standard of contactless IC card; the cards from different suppliers. The designer combined some frequent used command of RF IC card and then user could operate the cards with full function by sending simple command to the module. The module and antenna are integrated design. The impedance between RF module and antenna was tuned by impedance analyzer. And then the module has excellent performance and stability.