Multi-Tech Systems MT3334HD8 Modem Response Result Code Commands, Fn Load Default Configuration

3 AT Commands

&Fn Load Default Configuration

n = 0, 8, or 9 Default: &F8

MT3334HD8 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 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:

Table 2. Where the Modem Reads Configuration Parameters

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

ZReset Modem

The Z command resets the modem to its default configuration and clears the command buffer. The result is the same as turning the modem off and on. When you type ATZ, the state of the &W command determines where the default values originate. &W0 defaults come from the customized configuration in NVRAM, and &W1 defaults come from the factory default configuration in ROM. Because Z clears the command buffer, it must be the last command in a command string; normally it is issued by itself: ATZ.

Note that the Z reset command operates differently from the &F reset command. See Table 2 on page 21.

Modem Response (Result Code) Commands

The MT3334HD8’s modems can give responses to commands. The most common one is OK, but the modems also can alert you or your software to dial tones, busy signals, connection speeds, and whether the connection is made with error correction or compression enabled. These responses are called result codes, and they can be terse or verbose, Multi-Tech or standard, basic or extended.

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