Command mode
Command mode is a state in which the firmware interprets incoming characters as commands. It allows you to modify the device’s configuration using parameters you can set using AT commands. When you want to read or set any parameter of the XBee Smart Modem using this mode, you have to send an AT command. Every AT command starts with the letters AT followed by the two characters that identify the command and then by some optional configuration values.
The operating modes of the XBee Smart Modem are controlled by the AP (API Enable) setting, but Command mode is always available as a mode the device can enter while configured for any of the operating modes.
Command mode is available on the UART interface for all operating modes. You cannot use the SPI interface to enter Command mode.