Sierra Wireless DART 200 CDPD Modem - Manual (Page 85)

DART 200 CDPD Modem User’s Guide 5 DART Supported Protocols
PN1197-00 Revision 1.0 5-31
New for this version
The telnet binary mode (\Bn) was removed from the AT command set,
because a telnet remote login session should not be started with this
function enabled.
Binary mode considerations
Binary operation is available for telnet but only as a telnet escape
command. Requesting binary mode does not guarantee that it can be
established because the option is negotiated with the remote host. Query
telnet status after requesting binary mode to determine this, but do so
with caution.
Software flow control cannot be used since XON/OFF characters in the
data stream can not be distinguished from data with the same bit format.
Also, escape data streams containing the telnet escape command
character should be escaped by doubling the character. For example, if
the escape character is ^^ (decimal 30) and it appears in the binary data
stream, then modify the data by inserting a second escape character
adjacent to the first, for example:
1. Original data stream
• Data to modem [...69,123,24,30,49,....]
• Data from modem [...69,123,24,49,....]
2. Modified data
• Data to modem [...69,123,24,30,30,49,....]
• Data from modem [...69,123,24,30,49,....]
If binary data transfer is needed, the telnet mode of operation is probably
not the appropriate mechanism to use. The need to negotiate the option,
and the need for doubling the telnet escape character tend to make the
function awkward. Non-telnet modes such as UDP or TCP are much
better suited to binary data transfer.
Telnet operation
When the setup options are complete (\O1, \F0, \M1, \T0 are
recommended) establish a telnet session by dialing a telnet server, for
example, a bulletin board with an ATDTn.n.n.n/p command; where
n.n.n.n is the IP Address of the telnet server. The port number (p) is not
required because it defaults to the standard telnet port number (23).
? ?
NOTE:
Telnet servers are usually
quite slow, so be patient
when waiting for the
CONNECT message, and
again for the login
screen. Usually, after the
LOGIN session
operations speed up.
Follow the instructions
from the server to run
and terminate your
session. Usually, when
you quit the telnet session
the server breaks the
connection and a NO
CARRIER message
appears. If this does not
happen, escape from
online mode with the +++
escape sequence and
hang up with an ATH0.