B&B Electronics ZXT9-MB2A-KIT - Manual - Manual (Page 65)

Document Number: ZXTxRM-5110m
Page
65
To exit the AT command mode, send the ATCN (Exit Command Mode)
command (followed by a carriage return).
6.3.6.6 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 (pin 10) 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.
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 sec-onds, the modem returns to Idle Mode.
Note
: When parameters are sent, they are two bytes long with the least
significant byte sent first. Binary commands that return one parameter
byte must be written with two parameter bytes.
Commands can be queried for their current value by sending the
command logically ORed (bit-wise) with the value 0x80 (hexadecimal)
with CMD asserted. When the binary value is sent (with no parameters),
the current value of the command parameter is sent back through the
DO pin.
IMPORTANT:
In order for the modem to recognize a binary command,
the RT (GPI1 Configuration) parameter must be set to one. If binary
programming is not enabled (RT parameter value is not equal to ‘1’), the
modem will not recognize that the CMD pin is asserted and therefore
will not recognize the data as binary commands.