5.
The modem's operating mode
Two operating modes are available:
•
Command mode (using AT commands).
•
Transmitter-receiver mode or normal mode (serial data is transmitted via the radio link).
On power-up, the transmitter-receiver is in normal mode: it is able to send/receive data to/from a radio link accor-
ding to its current configuration parameters.
5.1.
Command mode
Command mode is used to read and update the modem's configuration registers using AT commands.
NOTE
AT commands can be locked by using ATPWD commands.
In command mode, the radio is disabled (both for receiving and transmitting), except when the test command is
used.
Entry into command mode: broadcasts a +++ sequence on the serial link. The three consecutive + characters
are only accepted if there are no characters either before or after the + + + sequence. The register (S214)
defines the length of the silence.
TIP 1
If you are using a terminal (such as a Hyperterm), you should send the + + + sequence with a text file (first
create a text file only containing the +++ characters, then in «Hyperterm», use the «Send text file» command
from the «Transfer» menu).
TIP 2
Exiting command mode: (return to transmitter-receiver mode).
•
send the serial command: ATO <cr>
When it receives a correct command, the modem responds:
•
«O»<cr> (ASCII character 0x4F) in order to accept the command (command OK).
•
«E»<cr> for an error.
•
a specific string on request.
5.2.
Transmitter-receiver mode
In transmitter-receiver mode, two protocols are available:
•
Transparent mode, without flow control.
•
Addressed mode, with flow control (cf S216 register).
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