Modes of operation
9XTend-PKG-R RS-232/485 RF Modem User Guide
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Send AT commands
Send AT commands and parameters using the syntax shown below.
To read a parameter value stored in the modem register, leave the parameter field blank.
The preceding example would change the modem’s Destination Address to "0x1F". To store the new value to non-
volatile (long term) memory, the Write (ATWR) command must subsequently be sent before powering off the modem.
When a command is sent to the modem, the modem will parse and execute the command. Upon successful execution
of a command, the modem returns an “OK” message. If execution of a command results in an error, the modem
returns an “ERROR” message.
To Exit AT Command Mode:
1. If no valid AT Commands are received within the time specified by CT (Command Mode Timeout) Command, the
modem automatically returns to Idle Mode.
[OR]
2. Send ATCN (Exit Command Mode) Command.
For an example of programming the RF modem using AT Commands and descriptions of each configurable
parameter, see
Use XCTU to configure the RF Modem
Binary Command mode
Sending and receiving parameter values using binary commands is the fastest way to change operating parameters
of the modem. Binary commands are used most often to sample signal strength [refer to DB (Received Signal
Strength) parameter] and/or error counts; or to change modem addresses and channels for polling systems when a
quick response is necessary. Since the sending and receiving of parameter values takes place through the same serial
data path as 'live' data (received RF payload), interference between the two types of data can be a concern.
Common questions about using binary commands:
•
What are the implications of asserting CMD while live data is being sent or received?
•
After sending serial data, is there a minimum time delay before CMD can be asserted?
•
Is a time delay required after CMD is de-asserted before payload data can be sent?
•
How does one discern between live data and data received in response to a command?
The CMD pin (GPI1) must be asserted in order to send binary commands to the modem. The CMD pin can be asserted
to recognize binary commands anytime during the transmission or reception of data. The status of the CMD signal is
only checked at the end of the stop bit as the byte is shifted into the serial port. The application does not allow control
over when data is received, except by waiting for dead time between bursts of communication.
If the command is sent in the middle of a stream of payload data to be transmitted, the command will essentially be
executed in the order it is received. If the modem is continuously receiving data, the radio will wait for a break in the
received data before executing the command. The CTS signal will frame the response coming from the binary
command request [refer to figure below].
A minimum time delay of 100 µs (after the stop bit of the command byte has been sent) must be observed before the
CMD pin can be de-asserted. The command executes after all parameters associated with the command have been
sent. If all parameters are not received within 0.5 seconds, the modem returns to Idle Mode.