Chapter 3 - Basic Modem Operation
3-7

Saving Settings and User Profiles

There are some cases where you may wish to save the settings you have made as
the default settings that are recalled when the Omni 288S is powered up. The
AT&WZ command selects the current settings as the power-on profile.
There are four profiles that can be changed by the user, and one factory default
profile. The following table lists the syntax for the command involved in storing,
recalling, and viewing the profile settings.
AT&VnViews the settings in profile (n-1); n=0 to 5; n=0 views current settings
AT&WnStores the current settings in user profile ‘n’; n=0 to 3
ATZnResets the current settings with the settings in profile ‘n’, n=0 to 4
Profiles 0 to 3: User profiles
Profile 4: Factory default profile
Helpful Hints for PC Computers
Most PCs are equipped with more than one serial port. Standard cables are
readily available from many suppliers. Usually, serial ports are manufactured in
two forms, either with a 25-pin male jack or a 9-pin male jack. For high speed
serial connections at 230.4Kbps or 460.8Kbps, use a low-capacitance cable.
Also, keep the cable as short as possible.
The serial port is driven by interrupts. Every interrupt needs a certain amount of
overhead processing time. Too many interrupts reduce the computer's efficiency.
The UART 16450 is very commonly used in serial port devices. For every
character (byte) received, it generates an interrupt. If your hardware allows it and
if your software supports it, replace the 16450 UART with a 16550 model. This
newer chip has an internal buffer and generates an interrupt for up to every 16
characters (several trigger levels are available). With this UART installed, you
may drive your serial port at 57600 bps and above.
While data is written from the transfer-buffer to your hard-disk, characters may be
lost at the serial port. This is due to the fact that disk-access interrupts have a
higher priority than serial port interrupts. If you are running at a high serial speed,
e.g. 230.4Kbps or 460.8Kbps, on your PC, be sure to enable the disk cache by
including SMARTDRV execution in your AUTOEXEC batch file.

Default Modem Settings for PC’s

The Omni 288S factory settings are configured for operation with PC type
computers and comm software. In most cases, no additional settings will be
required. The following are some of the default settings that are used for
operation with PC computers and software.