32
Chapter 3 - AT Commands
3.5 Configuration Storage and Recall Commands
The MT2834MR6 stores parameters in two places. It stores factory default parameters in read-only memory
(ROM), and customized parameters in nonvolatile random access memory (NVRAM). You cannot change the
default parameters in ROM; however, you can change parameters in temporary memory and then store them
in NVRAM as custom settings. You can then recall the custom settings as if they were factory default settings.
&Wn Store Configuration
n = 0 or 1
Default: &W1
The &W command stores current AT commands and S-register values in nonvolatile
memory, so you won’t lose your custom settings when you turn off the modem or reset it.
&W0 (or &W) stores all current AT command and S-register values in nonvolatile random
access memory (NVRAM) and configures the modem so that it reads your custom settings
in NVRAM when the modem is turned on or when it is reset with the Z command. (The &F
reset command will continue to read the factory default settings in ROM unless you store
the &F9 command.)
&W1 erases your custom settings in NVRAM when the modem is turned off or reset,
causing the modem to read the factory default settings in ROM when it is subsequently
turned on or reset.
For further information on how the &W command interacts with the reset commands, see
Table 3-2.
&Fn Load Default Configuration
n = 0, 8, or 9
Default: &F8
The MT2834MR6 modems store factory default AT command settings and S-register values
in read-only memory (ROM); they store your custom AT command and S-register values in
nonvolatile random access memory (NVRAM).
The &F0 (or &F) command resets the modem to the factory default values stored in ROM or
to your custom values stored in NVRAM, depending on whether you last stored an &F8 or
an &F9 command.
When &F8 is stored and an &F command is issued, the modem reads the factory default
settings stored in ROM.
When &F9 is stored and an &F command is issued, the &W setting determines whether the
modem reads settings stored in NVRAM or ROM. If the modem is set to &W0, it reads your
custom settings stored in NVRAM. If the modem is set to &W1, it erases your stored settings
(including the &F9 command) and reads the factory default settings stored in ROM. Many
communications programs issue the &F command automatically—the &F9 command allows
you to select your own defaults.
Note that for either an &F8 or an &F9 command to be effective after a reset it must be stored
using the &W0 command.
Table 3-2 summarizes how the &F and Z reset commands interact with the &W command;
note that the &F reset command operates differently from the Z reset command: