User's Guide

User’s Guide CDPD Operation
2110059 Rev 1.1 Proprietary and Confidential Page 37
Note that it is possible to read a value of 1 indicating auto-registration is enabled while, in fact, the
modem is not registered and is not attempting to register. It is possible to detect situations where
this has happened by also reading the Registration Result Code (+WS201). If the result code is
254 – Unregistered by user – then the modem will not automatically attempt to register.
This situation arises when one of these events occur:
• Manually commanded to de-register (+WPDEREG).
• Manually commanded to hang-up and de-register (H1).
• \SHDN input signal has been activated.
Manual registration can still be used while auto-registration is inactive, unless the \SHDN signal
remains active (low).
The modem will resume auto-registration attempts when one of these events occur:
• Modem reset (soft or hard) or power-cycle
• Command to force auto-registration to enabled state (+WS173=1)
• CDPD mode is re-entered (on the SB320 only)
5.4.3. PING
PING is a utility to test connections across an IP network. PINGs are packets of data with special
flags in the header which advise the protocol stack at the receiving end to echo the packet back.
The sender typically times the duration from transmission to echo receipt to determine the speed
of the network link. The application at the receiving end of a PING has no knowledge of the
transaction. It handled within Layer 3 of the protocol stack.
When the modem is registered, you can issue PINGs to the modem and it should reply. If you are
using a SLIP connection, the stack on the host will be responsible for replies to PINGs. If you use
either the UDP or TCP packet services in the SB300 Series modem, then the modem will handle
the PING without the host’s knowledge.
5.4.3.1. Obtaining a PING from the Modem
A detailed discussion of this process follows the outline of steps to test the modem’s reply to a
PING. (AT is omitted for brevity):
1. +WS46=4 to place the modem in CDPD mode (only required on the SB320).
2. +WS45=0 or 1 to select UDP or TCP packet service.
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. Using a network-connected PC, open a MS-DOS Prompt window.
9. At the MS-DOS command line enter:
PING <ip> where <ip> is the address of the modem. Do not use leading zeros in the IP
address components (there is a bug in the PC service).
The modem should reply and the PC will indicate the echo time. Four PINGs are issued by
this command option.
If the requests timeout without success, try allowing a longer wait time by adding the parameter
–w 2000. That will allow 2 seconds (2000 ms) for the echo before the PC will time out the
attempt. For a full list of PING command options, enter the command PING without parameters.