Command Line Interface
Command Line Interface Convention
Software Switching to Command Mode
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20 ms toggling on CTS control line needed to acknowledge switching from Data to Command
mode and vice versa.
Happy Flow
1. In data-mode the unit starts looking for the Escape-sequence if there is no data from DTE
(Data Terminal Equipment) for more than 20 ms (Start Guard Time).
2. If the unit detects the Escape-Sequence:
• The transmitter continues sending over the air the data received from DTE before Escape-
Sequence and buffers the data from DTE;
• The Receiver immediately stops forwarding to DTE the data received over the air and
buffers it instead.
3. The radio unit waits for 20 ms and then sends Escape-Acknowledge to DTE if there is no
data from DTE during 20 ms of Stop Guard Time.
4. The unit goes to command mode and discards Escape-Sequence from input buffer. The
modem is immediately ready to receive commands. At the same time it continues
buffering the data received over the air since step 2.
Escape-Sequence in Data
During its waiting in step 3, the unit receives data from DTE:
• The unit sends buffered Escape-Sequence from DTE to the air;
• The unit sends all buffered data received from the air since step 2 to DTE and stays in
data-mode (i.e. transmits data received from DTE over the air – including the just
received, unexpected, data and forwards data received over the air to DTE.)
