# Serial Programming/Modems and AT Commands/Commands N - Z

Serial Programming: Introduction and OSI Network Model -- RS-232 Wiring and Connections -- Typical RS232 Hardware Configuration -- 8250 UART -- DOS -- MAX232 Driver/Receiver Family -- TAPI Communications In Windows -- Linux and Unix -- Java -- Hayes-compatible Modems and AT Commands -- Universal Serial Bus (USB) -- Forming Data Packets -- Error Correction Methods -- Two Way Communication -- Packet Recovery Methods -- Serial Data Networks -- Practical Application Development -- IP Over Serial Connections
* Hayes-compatable Modems and AT Commands References:
* -- Special AT Commands and Character Sequences
* -- AT Commands A - M
* -- AT Commands N - Z
* -- AT& Commands

## AT Commands N - Z

This module explains the AT commands N to Z as used by a "generic" Hayes-compatible modem. Different modems use slightly different commands. However, this list is supposed to be as "generic" as possible, and should not be extended with modem-specific commands. Instead it is recommended to provide such command lists in an Appendix.

### N: Negotiation of Handshake Options

Syntax:
Description:
Controls whether during the handshake it is acceptable to fall back to a lower connection speed than specified by the S37 register. N0 indicates that fall back is not acceptable, N1 indicates that fall back is acceptable.
Result Codes:
Result Codes :
| Code | Description |
| OK | Parameter was valid |
| ERROR | Otherwise |
Related Commands and Registers:
* B: Select Communication Standard (in modems that also specify speed via this command)
* S37: Desired DCE Line Speed

### O: On-Line Command

Command Description Template
Syntax:
Description:
Return a modem to data mode when it is on line and in command mode.
Result Codes:
Result Codes :
| Code | Description |
| OK | Parameter was valid <description of success> |
| ERROR | Otherwise <description of failure> |
Related Commands and Registers:
* <Link list of related commands and registers>

### P: Select Pulse Dialing Method

Syntax:
Description:
Sets the default dialing method to pulse (rotary) dialing. The setting is valid until it is either changed by using the T command, or a T modifier with the D command.
Result Codes:
Result Codes :
| Code | Description |
| OK | Parameter was valid |
Related Commands and Registers:
* #D: Dial Command
** #P: Pulse Dialing Modifier
** #T: Tone Dialing Modifier
* #T: Select Tone Dialing Method
* #S14: General Bit Mapped Options Status Bit 5

### Q: Result Code Display Options

Syntax:
Description:
The command allows to configure if result codes are supposed to be send to the DTE or not.

#### Q

or

#### Q0

    (default) Result codes are send to the DTE.

#### Q1

    No result codes are send (silent mode).
Result Codes:
Result codes are only send if the option is turned on.
Result Codes :
| Code | Description |
| OK | Parameter was valid |
| ERROR | Otherwise |
Related Commands and Registers:'
* S14: General Bit Mapped Options Status Bit 2

### Sr=: Write to an S-Register

Command Description Template
Syntax:
Description:
<Description of the command, including information about the purpose and effects>
Result Codes:
Result Codes :
| Code | Description |
| OK | Parameter was valid <description of success> |
| ERROR | Otherwise <description of failure> |
Related Commands and Registers:
* <Link list of related commands and registers>

### Sr?: Read an S-Register

Command Description Template
Syntax:
Description:
<Description of the command, including information about the purpose and effects>
Result Codes:
Result Codes :
| Code | Description |
| OK | Parameter was valid <description of success> |
| ERROR | Otherwise <description of failure> |
Related Commands and Registers:
* <Link list of related commands and registers>

### T: Select Tone Dialing Method

Syntax:
Description:
Sets the default dialing method to tone (DTFM) dialing. The setting is valid until it is either changed by using the P command, or a P modifier with the D command.
Result Codes:
Result Codes :
| Code | Description |
| OK | Parameter was valid |
Related Commands and Registers:
* #D: Dial Command
** #P: Pulse Dialing Modifier
** #T: Tone Dialing Modifier
* #P: Select Pulse Dialing Method
* #S14: General Bit Mapped Options Status Bit 5

### V: Result Code Format Options

Syntax:
Description:
Sets result code format to words or digits:

#### V

or

#### V0

    digit responses (e.g. 1)

#### V1

    (default) word responses (e.g. CONNECT)
Result Codes:
Result Codes :
| Code | Description |
| OK | Parameter was valid |
| ERROR | Otherwise |
Related Commands and Registers:
* #Q: Result Code Display Options to turn on/off the responses.

### W: Negotiation Progress Message Selection

Syntax:
Description:
The command controls the contents and format of the CONNECT message:

#### W

or

#### W0

    (default). When connecting, the modem reports the DTE/DCE speed in the CONNECT message. The speed is reported only once, upon initial set up of the connection. Subsequent reports are disabled.

#### W1

    When connecting, the modem reports the line speed, error correction protocol, and the DTE/DCE speed. The data is reported only once, upon initial set up of the connection. Subsequent reports are disabled.

#### W2

    When connecting, the modem reports the line speed in the CONNECT message. The data is reported only once, upon initial set up of the connection. Subsequent reports are disabled.
Result Codes:
Result Codes :
| Code | Description |
| OK | if parameter was valid (0, 1, 2) |
| ERROR | Otherwise. |
Related Commands and Registers:'
* #X: Call Progress Options for selecting the details of the reporting message.
* #S31: Bit Mapped Options Status Bits 2-3.

### X: Call Progress Options

Syntax:
Description:
The command governs the type and verbosity of connect message responses. If the modem is in facsimile mode (+FCLASS=1), the only message sent to indicate a connection is CONNECT without a speed indication.

#### X

or

#### X0

    blind dial, no busy detect, CONNECT.

#### X1

    blind dial, no busy detect, CONNECT xxxx.

#### X2

    dial tone detect, no busy detect, CONNECT xxxx.

#### X3

    blind dial, busy detect, CONNECT xxxx.

#### X4

    full monitor, all messages, CONNECT xxxx.
where xxxx = DTE rate or DCE rate.
Note that the connect message response is a function of Wn, Xn and \Vn.
Result Codes:
Result Codes :
| Code | Description |
| OK | Parameter was valid (0,1,2,3,4,5) |
| ERROR | Otherwise |
Related Commands and Registers:
* W: Negotiation Progress Message Selection

### Y: Long Space Disconnect Options

Command Description Template
Syntax:
Description:
<Description of the command, including information about the purpose and effects>
Result Codes:
Result Codes :
| Code | Description |
| OK | Parameter was valid <description of success> |
| ERROR | Otherwise <description of failure> |
Related Commands and Registers:
* <Link list of related commands and registers>

### Z: Soft Reset Command

Syntax:
Description:
Soft reset is started. If modem is connected, connection is dropped. Last saved profile is loaded from NVRAM to RAM. No more commands are read from the command line.
Result Codes:
Result Codes :
| Code | Description |
| OK | Soft reset succeeded. |
| ERROR | Command failed. |
Related Commands and Registers:
* Serial Programming:Modems and AT Commands/& Commands#&F: load profile from ROM
* Serial Programming:Modems and AT Commands/& Commands#&V: show current profile or profile from NVRAM
* Serial Programming:Modems and AT Commands/& Commands#&W: save current profile to NVRAM
Serial Programming: Introduction and OSI Network Model -- RS-232 Wiring and Connections -- Typical RS232 Hardware Configuration -- 8250 UART -- DOS -- MAX232 Driver/Receiver Family -- TAPI Communications In Windows -- Linux and Unix -- Java -- Hayes-compatible Modems and AT Commands -- Universal Serial Bus (USB) -- Forming Data Packets -- Error Correction Methods -- Two Way Communication -- Packet Recovery Methods -- Serial Data Networks -- Practical Application Development -- IP Over Serial Connections
* Hayes-compatable Modems and AT Commands References:
* -- Special AT Commands and Character Sequences
* -- AT Commands A - M
* -- AT Commands N - Z
* -- AT& Commands