Sierra Wireless DART 200 CDPD Modem - Manual (Page 60)

DART 200 CDPD Modem User’s Guide 5 DART Supported Protocols
Sierra Wireless, Inc. 5-6
• Receive locking capability to allow the DART 200 to function as a
UDP server by holding off incoming messages until the preceding
message is answered
• Eliminates the need for the M-ES and Host modems to use a
common port number. The server uses the source address contained
in the incoming packet as the destination address for outgoing packet
• Backward compatibility with the basic UDP function in earlier
DART modems by an S-Register setting. When there are DART
modems involved in the UDP application that use non-server
software, activate this feature
These added features make the DART UDP server compatible with
industry standard client-server models where the client originates
communications and the server waits for incoming communications
requests.
UDP server setup options
In addition to the new options discussed here, the same setup options
used with basic UDP, as described on p. 5-4, also must be considered
before proceeding to step 1.
1. Set the defining setup parameter for the UDP server function ( *An -
select server type) to 2 with an AT*A2 command. Selecting this
option enables the UDP server function. The default value for this
parameter is *A0 (no server active). This is appropriate if the MAS
application always operates in client mode; always originates the
connection request with an ATDP command.
2. With the UDP server option enabled, choose the method used to
answer incoming calls. The preferred method is to set S-Register 0 =
1 with an ATS0=1
command, which puts the modem into permanent
auto answer mode. The alternative is for the MAS to use the answer
command, ATA. This command could be used in response to a
RING message, or in anticipation of an incoming call. However, in
the latter case, since the command is only active for 20 seconds it has
to be used in a programming loop to receive a call.
3. (Optional) Select the port to listen for incoming messages on. For
basic UDP the listening port is fixed at 2100. However, with the
UDP server the listening port can be set using the *L command. The
command format is AT*Ln where n is the desired listening port; a
decimal number in the range of 1025 to 4999 for compliance with
industry standards.
4. If the listening port is changed, save it with an AT&W. The default
value for the listening port is still 2100 for backward compatibility
with basic UDP.
The remaining setup options for the UDP server are controlled by the
contents of S-Register 82, including:
• Friends Only mode
? ?
NOTE:
When the listening port
is changed it is not
active until the server is
stopped and restarted,
or the modem is reset
with an AT-R or a
power cycle.