Sierra Wireless DART 200 CDPD Modem - Manual (Page 58)

DART 200 CDPD Modem User’s Guide 5 DART Supported Protocols
Sierra Wireless, Inc. 5-4
Because UDP is a connectionless protocol, a single M-ES can
communicate with multiple M-ESs at the same time as long as timing
considerations are closely followed.
When a DART 200 receives a datagram from another M-ES:
1. The DART 200 removes the source address information (IP Address
and port number) and saves it to use as the destination address for its
response message.
2. After the DART 200 responds to client #1, it is free to receive and
respond to requests from client #2, #3, and so on. The requests and
responses from clients can be interspersed, as long as no request
comes in from a client before a response is given to the previous
client. If that occurred, the response intended for #1 would go to #2,
followed by the normal response to #2.
Unless the timing of requests can be scheduled or controlled to prevent
this from happening, avoid this type of operation with basic UDP. The
UDP server is designed to handle this, as described in UDP server, p.
5-5.
The DART 200 with UDP server capability uses a bit in Status
(S)-Register 82 to enable and disable basic UDP operation; basic UDP
operation is enabled. If you do not have an older DART compatibility
requirement, it is strongly recommended that basic UDP not be used.
Refer to the bullet point on backward compatibility on p. 5-7, for
information on enabling and disabling the basic UDP mode of operation.
Basic UDP setup options
The following items must be set so the DART 200 can 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 using the
AT commands, ^A, \N, and \J.
In addition, the following items are required for basic UDP operation:
• Automatic registration - as described in Automatic registration,
p. 8-6
• PAD mode - \O0 in the profile. Refer to \O command in Appendix F,
DART AT Command Set for details on using this command.
• S-Register 82 set to 2 (default). Refer to the bullet point on backward
compatibility, p. 5-7, for details on setting this S-Register
Many of the following profile parameters may apply and need to be
evaluated. Some need to be set to provide the proper application
operating environment, others can be allowed to default.
? ?
NOTE:
The DART default is
basic UDP active. It is
strongly recommended
that this feature be
disabled so that the
UDP server function
will be active.