[Antenna Interface]： SMA-K [Size]：84*82*25mm [Interface]： RS232/RS485 [Weight]： 133±5g [Introduction]：E840-DTU(NB-02) can realize the communication between the serial port device and network server via the NB network. With simple AT commands, users can easily use this product to achieve bidirectional transparent data transmission from the serial port to the network. The transparent transmission is between UART devices（referring to PC） and net servers (replaced by TCP testing tools).