PinPoint CDMA User Guide Version 1.0
AirLink Communications, Inc.
Page 23
February 22, 2003
6.2.1
AT Mode
AT commands are used to configure the modem, command it to do something, or
query a setting.
AT commands must always be terminated by
<CR>
(ASCII character 0x0D).
If
E=1
(Echo On), the AT command (including the terminating
<CR>
) will be output
before any responses defined in the next section.
Response Framing
Two settings affect the format of AT command output:
V
(
Verbose
) and
Q
(
Quiet
).
If
Q=1
(Quiet On), no result codes are output whatsoever, so there is no response
generated by a (non query) command. If
Q=0
(Quiet Off), result codes are output.
The format of this output if then affected by the
Verbose
setting.
If Quiet mode is off, the result code is affected as follows: For
V=1
(Verbose mode),
the textual result code is surrounded by
<CR><LF>
and any AT query response is also
surrounded by
<CR><LF>
; for V=0, (Terse mode), a numeric result code is output with
a single trailing
<CR>
(no
<LF>
is output), while any AT query response is followed
by
<CR><LF>
(there is no preceding output).
For example, possible output to the AT command “
AT<CR>
” (assuming quiet mode is
not on) is:
0
<CR>
- if V=0
<CR><LF>
OK
<CR><LF>
- if V=1
6.2.2
PPP Mode
In PPP mode, the modem acts as a PPP server, providing an IP address, and DNS
servers (if available) to the Host.
PPP mode is entered be using the “
AT\APPP”
command. It can also be entered by
issuing a Dial TCP to 10.0.0.1 (e.g. ATDT10.0.0.1) or entering the “CLIENT”
command. At this point the modem assumes that the host will start PPP negotiation.
The IP received by the host in the resulting negotiation will either be a private (non-
routable) IP or a public (network-routable) IP provided by the OEM Modem’s
network, depending on the settings of
S300
. The value of this IP can be determined
beforehand by querying
S110
.
Using a private IP insulates the PPP client from changes in IP addresses of the
underlying network, as the AirLink modem will perform basic NAT-like address
translation on all packets. However, if a public IP address is being used, any changes
in the IP (as determined by the underlying communications network) will result in
the PPP link to the host being disconnected, requiring the host to reinitiate it.
The host can exit PPP mode by deactivating DTR (if
S211=0
) or issuing the
+++
AT
escape sequence.
Note that DTR needs to be asserted (or
S211=1
) by the host before PPP mode can be
entered.
