Sierra Wireless DART 200 CDPD Modem - Manual (Page 71)

DART 200 CDPD Modem User’s Guide 5 DART Supported Protocols
PN1197-00 Revision 1.0 5-17
4. Once the data block is received it is ready for processing. Any
necessary error-checking, resequencing, and so on, is handled by the
TCP software and is not the responsibility of the MAS. The handling
of network connectivity issues (such as loss of carrier), as opposed to
data delivery and sequencing (provided by TCP), is the responsibility
of the MAS. Refer to Error recovery, p. 8-4, for guidelines on error
handling.
5. Once the first data block has been received, the server system (MAS
or central site depending on application design) could reply to the
client system with data of its own, or it could wait for additional data
from the client. The variations at this point are numerous and entirely
dependent on application design.
6. When data transfer is complete the session terminates. As with the
initial communication step, either end could terminate; it is another
application design decision, but usually, the client terminates.
7. If the MAS is the server, it receives a NO CARRIER message and
returns to command mode when the client terminates the session. If
the MAS is the client, it performs an escape function to return to
command mode followed by a hang-up command (H). Refer to
Appendix F, DART AT Command Set, for a description of H.
Setup options
The following items must be set to enable the DART 200 to operate on
the CDPD network:
• IP Address (^A)
• Side Preference - \N in the modem profile
• Channel restrictions - \J in the modem profile
Refer to Basic modem personalization, p. 2-6, for a review of the details
on the AT commands ^A, \N, and \J.
In addition the following items are required for basic TCP operation:
• Automatic registration. Refer to p. 8-6 for details
• PAD mode - \O0 in the profile. Refer to \O command in Appendix F,
DART AT Command Set
If application design dictates that the MAS accepts connection requests,
activate the TCP server by setting the
*A (select server type) AT
command to 1 with an AT*A1 . Selecting this option enables the TCP
server function. The default value for this parameter is *A0 (no server
active). The default option is appropriate if the MAS application always
operates in client mode; always originates the connection request with an
ATDT command.