A device sends data to the XBee/XBee-PRO DigiMesh 2.4's UART through pin 3 DIN as an asynchronous serial signal. When the device is not transmitting data, the signals should idle high.
For serial communication to occur, you must configure the UART of both devices (the microcontroller and the XBee/XBee-PRO DigiMesh 2.4) with compatible settings for the baud rate, parity, start bits, stop bits, and data bits.
Each data byte consists of a start bit (low), 8 data bits (least significant bit first) and a stop bit (high). The following diagram illustrates the serial bit pattern of data passing through the device. The diagram shows UART data packet 0x1F (decimal number 31) as transmitted through the device.