32
MultiModemBA User Guide
Loading Factory Defaults &F
The
&F
command provides a choice between customized configuration settings in RAM and the
factory default configuration settings in ROM. The
&F8
and
&F9
commands define the function of the
&F
command.
The modem is shipped from the factory with a pre-configured set of command and S-Register default
settings. This set of factory defaults can be recalled by issuing the
&F
command.
In addition to being able to recall the factory-installed defaults, the
&F
command can also recall those
defaults stored under
&W0
.
This is done using the
&F9
command. If you have stored parameters with the
&W0
command and
wish these settings to always be used as your defaults, you would enter
&F9&W0
.
To return the
&F
command to read factory installed defaults, enter
&F8&W0
.
&F8
is the factory
default.
Many datacomm program issue the
&F
command automatically- the
&F9
command allows the user
to select their own factory defaults. Note that the
&F8/&F9
commands should be used with
&W0
.
Following is a summary of how the &F and Z reset commands interact with the &W command; note
how the &F reset command operates differently from the Z reset command:
Previous Command AT&F Power-On and ATZ
AT&W1 (default) ROM ROM
AT&W0 ROM NVRAM
AT&F8&W0 ROM NVRAM
AT&F9&W0 NVRAM NVRAM
Modem Reset Z
The
Z
command can be used to reset the entire
Command Mode buffer and the result is the same as
if you had disconnected, and then reconnected power to the modem. When an
ATZ
command is
executed, the state of the &W command determines where the default values originate.
&W0
defaults
come from RAM and
&W1
defaults come from ROM.
Unix UUCP Spoofing $SP
The modem can be configured in a Unix environment that employs ACK flow control as a means of
monitoring data integrity. The modem can do
“UUCP spoofing”
, where the modem is able to generate
ACKs at the DTE interface. Data is transmitted more time efficiently because the delay of waiting for
data to be received, then for an ACK to be returned at the remote end, is eliminated. The $
SP1
command enables UUCP spoofing and the default command
$SP0
disables UUCP spoofing.
Async/Sync Mode Switching &M
This command can be used to set the on-line mode to either synchronous or asynchronous.
AT&M0
will set the modem to Asynchronous mode, and all communications will be Asynchronous, in both
On-line and Command modes.
AT&M1
causes the modem to communicate asynchronously when in
Command mode and switch to synchronous mode while on-line. The modem defaults to
&M0
(asynchronous communications) on reset or power-up.
Synchronous Transmit Clock Select &X
The &X command selects the Synchronous Transmit Clock Source in conjunction with DIP-Switch
#11. DIP-Switch #11 in the UP position enables External clocking. DIP-Switch #11 in the DOWN
position enables Internal clocking (default position). External clocking is when the DTE provides
transmit clocking to the modem on pin 24 of the RS-232C interface.