User's Guide

The Operational View SB300 Series
Page 34 Proprietary and Confidential 2110059 Rev 1.0
5.3.1. Active and Auto-register NEI Indices
The modem keeps two separate index entries to the NEI table. These indices have an intricate
inter-relationship that you should understand.
Auto-registration uses the index at +WS176 (Auto-register NEI Index). Manual registration and
manipulation of the NEI table are based on an index at +WS197 (Active NEI Index).
When the modem registers an NEI, the index of the NEI used (manually or automatically) will be
stored in the Auto-register NEI Index (+WS176). This means that auto-registration will always
use the last registered NEI unless the Auto-register NEI Index is changed while the modem is de-
registered in manual (+WS173=0) mode.
Changing the setting in the Auto-register NEI Index while the modem is registered causes the
modem to de-register the old NEI address. This happens in both manual and auto-register modes.
If the modem is set to auto-register (+WS173=1) then the modem will go on to attempt to register
the new NEI.
Register +WS197 (Active NEI Index) is quite independent of any currently registered NEI and
can be changed freely. This allows access to other table entries while registered without affecting
the registration status.
The manual registration command (+WPREG) will use the Active NEI Index (+WS197) as the
address to register. It will also store the value of the Active NEI Index (+WS197) into the Auto-
register NEI Index (+WS176) so that it becomes the default address for future auto-registration.
This copying of the index takes place even if the manual registration fails.
In summary, the Auto-register NEI Index value will follow the Active NEI Index value if there is
an attempt to register manually. The Active NEI Index can change freely and is not influenced by
changes in the Auto-register NEI Index.
5.3.2. Manual Registration
When the modem is set for manual registration (+WS173=0) it will not attempt to locate a CDPD
channel until commanded to register (+WPREG) or the command to set a channel (+WPCHAN)
is set to 0 (automatic selection). You may select a channel first if desired. If you do not assign a
channel, or if you force automatic channel selection by setting +WPCHAN=0, the modem will
scan for one when the registration command is issued.
5.3.2.1. Select a Channel
If you assign a channel, the modem will use that channel for registration attempts. If registration
fails on the assigned channel NO automatic attempts are made to locate another channel.
NOTE: If you set SPNI matching and also use +WPCHAN to assign a channel manually, the
assigned channel will not lock if the SPNI fails to match. The modem will not be able to register
because it will not look for another channel if you have manually set a channel. The channel lock
can be checked using +WPRSSI.
Assign a Channel
To assign a channel for use by the modem issue the AT command +WPCHAN=n where n is the
channel number to assign. The modem will go to that channel. Subsequent use of +WPRSSI will
report the strength of signal and if the channel has been acquired.
Changing the channel assignment while the modem is registered will not change the registration
status. The modem may lose connectivity if the new channel does not present sufficient signal.
Where the cellular carrier forces CDPD channel hopping the modem will follow the hops
regardless of the user assigned channel.