Chapter 4 - S-Registers
4.4
AT Commands Affecting S-Registers
For maximum throughput, the MT2834MR6's default configuration is for originating a call to another 33,600 bps modem that supports error correction, data compression, and flow control. If the receiving modem is not compatible, the MT2834MR6 can match any ITU-T or Bell standard modem (but not proprietary protocols).
If you require a different configuration for your application, for example, if you want to use an MT2834MR6 modem strictly as an autoanswering device, or for service that does not support error correction, you can selectively change the command parameters and S-register values in active memory and save the new values by using the &W command.
The &W0 (or &W) command stores all current AT command and S-register values into 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 read-only memory [ROM] unless you also store the &F9 command. See Chapter
3.) For convenience, you can incude the &W command in the same command string that sets the new values in active memory, as in the following example:
AT&E2$SP1#L3$R0$MB19200$SB115200$EB1S0=10&W0<CR>
The &W1 command erases your custom settings in NVRAM the next time 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.
Before you use the &W command, check the modem’s current operating parameters by using the L5, L6, and
L7 commands.
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