[Introduction]：E840-DTU(4G-02)E is an industrial 4g modem developed for serial port devices and network servers to transmit data to each other through a network. It is an LTE-FDD/WCDMA/GSM wireless communication data transmission modem with diverse receiving functions, supporting LTE-FDD, DC-HSDPA, HSPA+, HSDPA, HSUPA, WCDMA, EDGE, and GPRS network