AT Commands N-Z

		AT Commands N-Z

N Automode detection :

Options : N0, N1 Default : N1

The N command is linked with register S37 to determine how the modem reacts when automode detection is disabled.

N0	When originating or answering, handshake only at the communication rate specified by Register S37 and Bn and no fallback. In brief this command disables automode detection.
N1	When originating or answering, start handshake only at the communication standard specified by Register S37 and Bn. During handshake, fallback to a lower speed may occur except in \N1 mode. In brief this command enables automode detection.

\N Error correction mode select :

Options : \N0, \N1, \N2, \N3, \N4, \N5 Default : \N3

The \N command sets the preferred error correction mode. See the chapter Error correction and data compression for more information.

\N0	disables error correction. Speed buffering is enabled.
\N1	enables direct mode. Both error correction and speed buffering are disabled.
\N2	enables an MNP error corrected connection only.
\N3	enables auto reliable mode. If an error corrected connection cannot be established the modem falls back to a non-error corrected correction.
\N4	enables reliable mode. This command should be used when an error corrected connection must be established.
\N5	same as \N3
\N7	same as \N3

"N V.42bis dictionary size :

Options : "N0, "N1, "N2 Default : "N2

This command controls V.42bis dictionary size.

"N0	512 bytes.
"N1	1024 bytes.
"N2	1536 bytes.

O Return to on-line mode :

Options : O0, O1, O3-14

Issuing the O0 command after the escape sequence has been issued or an ON-to-OFF DTR transition takes place (only with &D1 in operation) forces the modem to go back on-line and issue the appropriate connect message. With no connection established the O0 command returns the ERROR result message.

The O1 command begins an equaliser retrain sequence, then returns to on-line state.

Issuing O3-14 forces the modem to a new rate that is user defined. (New rates are defined in S62).

"O Select V.42bis Maximum String Length :

This command selects the string size for V.42bis compression. It can have values 6 to 64 and the default value is 32.

P Pulse dial :

By default the modem uses tone dialling when executing a dial string. However, entering the P command will return the modem to the pulse dialling option. Alternatively, the P can be entered in the dial string (e.g. ATD P 01234 567890). Pulse dialling will remain the default until tone dialling is specifically selected.

Q Quiet control :

Options : Q0, Q1 Default : Q0

The Q command enables or disables result codes and messages. By default the messages, such as ERROR or BUSY, are displayed at the DTE. This is a useful indication as to the status of the modem for users and software developers alike. It is sometimes desirable to disable these messages; for example, when printing hard copy of incoming data so that they do not appear in the listing.

Q0	enables result codes/messages.
Q1	disables result codes/messages.

&Q Communication Mode Option :

Options : &Q0

This command is the Hayes command and is the same as using the command &M command.

\Q DTE Flow Control Options :

Options : \Q0, \Q1, \Q2, \Q3 Default : \Q3

This command selects the flow control method the modem provides to the DTE to prevent the modem's buffer from overflowing with data. A data buffer holds the data until the modem is ready to transmit it. When the data buffer is full, flow control instructs the DTE to stop sending to the modem while the modem continues to send characters.

\Q0	Disables flow control.
\Q1	XON/XOFF software flow control.
\Q2	CTS flow control to DTE.
\Q3	RTS/CTS hardware flow control.

&R CTS/RTS Option (non-CTS flow control mode) :

Options : &R0, &R1 Default : &R0

The functions of CTS are determined by this command.

&R0	CTS follows RTS (Synchronous modes only).
&R1	CTS always true.

S Display/set S register :

Options : All S registers

The S command can be used either to set or to view the value in the S register nominated or to set the register specified as the currently selected register.

ATS10=255 <Return> sets register S10 with the value 255.

ATS3? <Return> displays the value in register S3.

ATS4 <Return> sets register S4 as the currently selected S register.

If an attempt to enter a value outside the range of the S register is made, the maximum or minimum value is assumed and stored in the register.

Note: Some S registers are read only.

&S DSR (Data Set Ready) control :

Options : &S0, &S1 Default : &S0

DSR is the signal sent to the DTE indicating that the modem is ready to communicate. The &S0 command forces DSR high (ON) at all times. This may be required by certain communications software.

&S1 makes DSR high (ON) when the modem is ready to communicate, i.e. after answer tone is detected until the loss of carrier.

T Tone dial :

Entering the T command selects tone dialling as the current dialling method until pulse dialling is explicitly selected. Tone dialling is the modem default and adaptive tone dialling is enabled on the first dialled call after a reset. See the chapter automatic dialling for full details.

Both pulse and tone dialling can be used in the same command line. For example, ATD T 9 W P01234 567890 uses tone dialling to dial the 9, waits for the secondary dial tone from the exchange and pulse dials the remainder of the dial string.

&T Modem self tests :

Options : &T0, &T1, &T3 to &T8 Default : &T4

The &T command selects one of five self tests used by the modem to pinpoint a failure in a communications link. Test duration is determined by the contents of register S18. See chapter Diagnostic and test facilities for more information.

&T0	terminates the current test in progress.
&T1	initiates a local analogue loopback test in accordance with ITU-T V.54 (loop 3).
&T3	initiates a remote digital loopback test of the local modem in accordance with ITU-T V.54 (loop 2).
&T4	grants a remote digital loopback request from the remote modem.
&T5	denies a remote digital loopback request from the remote modem.
&T6	initiates a remote digital loopback test in accordance with ITU-T V.54 (loop 2).
&T7	initiates a remote digital loopback test in accordance with ITU-T V.54 (loop 2) with self test.
&T8	initiates a local analogue loopback test in accordance with ITU-T V.54 (loop 3) with self test.

\T Set inactivity timer :

Options : \T0, \T1-90 Default : \T0

The \T command allows the modem to disconnect if no data activity has occured for the selected period of time.

\T0	Disable inactivity timer.
\T1-90	Length in minutes.

V Verbose/numeric result code selection :

Options : V0, V1 Default : V1

Result codes or messages returned to the DTE from the modem can be either numeric or verbose. In the numeric form a number is used to indicate the result code. This is useful when the modem is under software control as the codes can be more easily interpreted by a software program.

In the verbose or English form the messages appear as ERROR, NO CARRIER etc. and are more user-friendly when the modem is under manual control.

V0	selects the numeric form.
V1	selects the verbose form.

&V View current configuration :

The &V command displays the modem's current configuration.

\V Protocol Result Code :

Options : \V0, \V1 Default : \V1

This command option only responds with W0 and W2 options.

\V0	Disables the protocol result code (e.g. CONNECT 9600).
\V1	Enables the protocol result code (e.g. CONNECT 9600/LAPM).

W Select Extended Result Codes :

Options : W0, W1, W2 Default : W2

Result Code control determines which result codes will be used to describe the type of connection and protocol that results from handshaking and negotiation.

W0	CONNECT result code reports the DTE speed.
W1	CONNECT result code reports the DTE speed. The CARRIER, COMPRESSION, and PROTOCOL extended result codes are enabled.
W2	CONNECT result code reports the line speed (DCE speed).

X Select Result Codes/Call Progress Options :

Options : X0, X1, X2, X3, X4 Default : X4

This command enables tone detection options used in the dialling process. As these functions are chosen, the modem's result codes are also affected. This command is therefore frequently used to control the modem's responses. The primary function of this control is to control the modem's call response capabilities.

X0	Display CONNECT or "1" for all speeds.
X1	Display connect message according to ATW and AT\V, blind dial, and ignore busy tone.
X2	Display connect message according to ATW and AT\V, wait for dial tone and again ignore busy tone.
X3	Display connect message according to ATW and AT\V, blind dial, but check busy tone after dialling.
X4	Display connect message according to ATW and AT\V, wait for dial tone and check busy tone after dialling.

\X Set XON/XOFF Passthrough Option :

Options : \X0, \X1 Default : \X0

This command is valid only if XON/XOFF flow control is enabled, such as \G1 or \Q1; otherwise XON/XOFF will not be detected by the modem, so always passthrough.

\X0	Process XON/XOFF per \G and \Q option, if XON/XOFF flow control is enabled, do not pass XON/XOFF to the remote modem or local DTE.
\X1	Process XON/XOFF per \G and \Q option, always pass XON/XOFF to the remote modem or local DTE.

Y Dummy command :

Options : Y0, Y1
This is a dummy command for compatibility purposes

The Y0 command and Y1 command both do the same thing and Send OK to the DTE.

Z Reset modem to Factory Default :

The Z command restores all the modems parameters to their factory settings.

? Read selected S register :

This command reads and displays the currently selected S register. The currently selected S register is chosen by using the Sn command (where n equals the number of the register).