User's Guide

User’s Guide CDPD Operation

2110059 Rev 1.0 Proprietary and Confidential Page 41

3. Optionally assign a channel with +WPCHAN=n where n is the channel to use.

4. Optionally verify the channel acquisition with +WPRSSI looking for the second value in the

return string to be 3.

If the modem is using auto-registration (+WS173=1) skip to step 7.

5. +WS197=n where n is the index (1-4) of the NEI to register, to select the NEI

6. +WPREG to register on the CDPD network. The modem will reply as noted in the section

above on manual registration.

7. +WS56? to query the registration status. Repeat this command until it returns a value of

1 (registered) or until the host chooses to timeout, failing the connection.

8. +WS212=<port> where <port> is the port number (1025-4999) that the modem will be

calling on and listening to. The modem will only accept packets addressed to this port. The

factory default is 2100.

9. D<dest> where <dest> is the destination IP and port number to send your data to. See the

AT Command Reference for details on this command. The modem will reply with

CONNECT at which point you are in data state.

The modem is now ready to accept host data for packet assembly and transmission to the network.

Any incoming packets, from an originator other than the <dest> will be ignored. Incoming

packets from the <dest> address will be passed to the host. This allows the host to exchange data

with a specific station.

Detailed Discussion

The first two steps simply place the modem in CDPD UDP mode. The modem’s packet service is

set in register +WS45 (Packet Service) by step 2. Setting this value to 0 will enable the modem’s

UDP stack. This can be done before or after registration on the network so auto-registration can

occur before this step.

The registration process can be more closely controlled with steps 3 through 6. Steps 3 and 4 can

be used in auto-register as well as manual register settings.

To send data over the network in a UDP client session the user must enter a data state connection

to the network with a specific IP address and port number. The On-line command (O) can be used

with the modem using the default IP address and port. Unfortunately, there is no way for you to

verify what this destination is, so we recommend you issue the dial command with an explicit

destination each time you start a client session.

The listening port (+WS212) must be set to the desired port number to communicate over. Both

the client and server must share this port number.

The IP of the destination can be any valid IP. Client sessions do not apply the Friends Only

restrictions. If the Dial command is given bad syntax including an invalid destination IP or port

number, then it will return the ERROR result code.

The Dial command can handle the network registration process using the NEI indexed by the auto-

for details. This means steps 3 through 6 can be omitted if desired.

The response to the Dial command will depend on the setting of register +WS179 (Registration

Wait Status). If the setting is 0 (the default) then the CONNECT code is returned regardless of the

success or failure of the modem to register. If the modem was not registered then the dial

command must perform the task. The UPD PAD is ready and you may start assembling data into

a packet while the registration process proceeds in parallel. The modem will buffer the data until

the modem registers. A failure to register is NOT reported to the host, and the packet can be lost.