Digi XBee, Руководство пользователя, Страница: 49 / 307

Operation Modes of operation
XBee/XBee-PRO® S2C ZigBee® RF Module 49
Receive mode
This is the default mode for the XBee/XBee-PRO ZigBee RF Module. The device is in Receive mode
when it is not transmitting data. If a destination node receives a valid RF packet, the destination node
transfers the data to its serial transmit buffer.
Command mode
Command mode is a state in which the firmware interprets incoming characters as commands. It is
only available over the UART when not using the Smart Energy firmware.
API Operation describes an
alternate means for configuring devices that is available with the SPI and with Smart Energy, as well
as over the UART with ZigBee code.
Enter Command mode
To get a device to switch into this mode, you must issue the following sequence: +++ and observe
guard times before and after the command character.
The default sequence to transition to Command mode is:
n
No characters sent for one second [ GT (Guard Times) parameter = 0x3E8].
n
Three plus characters ( +++ ) input within one second [ CC (Command Sequence Character)
parameter = 0x2B.].
n
No characters sent for one second [ GT (Guard Times) parameter = 0x3E8].
When you send the Command mode sequence, the device sends OK out the UART pin. The device may
delay sending the OK if it has not transmitted all of the serial data it received.
When the device is in Command mode, it starts the Command mode timer ( CT command) and can
receive AT commands on the UART port.
You can customize the command character, the guard times and the timeout in the device’s
configuration settings. For more information, see
CC (Command Character) , CT (Command Mode
Timeout) and GT (Guard Times) .
Troubleshooting
Failure to enter Command mode is often due to baud rate mismatch. Ensure that the baud rate of the
connection matches the baud rate of the device. By default, the
BD parameter = 3 (9600 b/s).
Send AT commands
Once the device enters Command mode, use the syntax in the following figure to send AT commands.
Every AT command starts with the letters
AT , which stands for "attention." The AT is followed by two
characters that indicate which command is being issued, then by some optional configuration values.
To read a parameter value stored in the device’s register, omit the parameter field.
The preceding example changes the device's destination address (Low) to 0x1F.