Fax Modem (250-3581) AT Commands Faxback Doc. # 5797
This document describes alphabetically the commands available to your
Fax Modem, and show the range of possible selections and the default
values.
2.1 COMMAND GUIDELINES
Each AT command has a list of possible parameters with its default
value. The default value is loaded at initialization, i.e., power
turn on or ATZ command. If a command requires a parameter but no
parameter is entered, the Fax Modem assumes the parameter is zero.
Invalid commands or parameters return the ERROR message.
The command line may contain a single command or a series of
commands. The commands may be separated by a space for readability.
The command lines can be up to a terminating character is entered.
The default terminating character is a carriage return (ASCII 013),
but this may be changed by writing a different value to register S3.
The command line may be edited using the backspace character
(ASCII 088). This value may be programmed using the S5 register.
However, the backspace will not work for values of 0 and greater
than 127, or for the current value of the terminating character.
All command lines must begin with AT entered as capital or lower
case letters. A command line can be terminated at any time by
issuing CTRL-X (ASCII 018) after entering the AT attention code.
The command line will be ignored and an OK result message will be
issued. The A/ command may be used to repeat the last command line.
The A/ does not require a termination character or the AT attention
code.
The escape code sequence returns the FAX Modem to the command mode
from the data mode. A time delay must occur between the last
character transmitted and the first character of the escape code.
The guard time delay can be changed by writing a value to register
S12; (default 1 second). The escape code character must occur three
times in succession for and escape.
Parameters that are entered for the AT and AT& commands are limited
in value to 0-255, where the parameter is "MOD"ed with 256. The
result must be within the specified range; if it is not, the ERROR
message is issued.
Parameters entered for and S registers are also "MOD"ed with 256 and
the result is stored in the S register. Parameters that are out of
range are stored in the S register, however, no ERROR message is
reported. Functionally, however, the lower and higher limit is
observed.
Parameters entered for the AT/ and AT% commands follow the same
method, except that if the parameter is out of range, the upper
limit is stored and no ERROR message is reported.
COMMAND FUNCTION DEFAULT
A/ Re-execute Command none
ATA Answer none
ATBn Set CCITT or Bell Mode 1 (US) *
0 (Japan)
ATCn Carrier Control 1
ATDn Dial P
ATE Command Echo 1 *
ATHn Switch Hook Control none
ATIn Identification none
ATLn Speaker Volume 2 *
ATMn Speaker Control 1 *
ATNn Modulation Handshake 1 *
ATOn Return To The On-line State none
ATP Set Pules Dial as Default none *
ATQn Result Code Display 0
ATSn? Reading S Register none
ATSn=x Writing to S Register none
ATT Set Dial Tone as Default none *
ATVn Result code Form (Message Control) 1 *
ATWn Negotiation Progress Reporting 0 *
ATXn Extended Result Codes 4 *
ATYn Control Long Space Disconnect 0 *
ATZn Reset none
AT&Cn DCD Option 0 *
AT&Dn DTR Option 0 *
AT&F Restore Factory Configuration none
AT&Gn Set Guard Tone 0 *
AT&Jn Telephone Jack Selection 0 *
AT&Kn DTE/FAX Modem Flow Control 3 *
AT&Ln Line Type 0 *
AT&Mn Communication Mode (&Qn) *
AT&Pn Dial Pules Ratio 0 (US) *
AT&Qn Communication Mode 5 *
AT&Rn RTS/CTS Option 0 *
AT&Sn DSR Option 0 *
AT&Tn Test And Diagnostic 4 *
AT&V View current configuration and
Store User Profile none
AT&Wn Store User Profile none
AT&Yn Designate Default User Profile 0
AT&Zn=x Store Phone Number none
*Command is saved in NVRAM.
A/ RE-EXECUTE COMMAND
Re-executes the most recent AT command string. The principle
application of this command is to place another call (e.g., Dial
command) that failed to connect due to a busy line, no answer, or
a wrong number. This command must appear alone on a command line
and must be terminated by the "/" character. (A <CR>) should not
be entered to terminate the command.
ATA ANSWER
This must be the last command entered into the command line. The
FAX modem proceeds with the connect sequence in answer mode. The
FAX Modem will enter the connect state after exchanging carrier with
the remote FAX Modem. If no carrier is detected within a wait period
specified in register S7 (default = 30 seconds), the FAX Modem will
disconnect. Any character may be entered via the DTE during the
connect sequence to abort the command.
Bn SET CCITT OR BELL MODE
Selects between CCITT and Bell modes for 2400, 1200, and 300 bps.
This command is not valid when the ATNI command (automode detection
enabled) is in effect.
ATB0 = Selects CCITT V.22 bis, V.22, and V.21 standards for
communication at 2400, 1200, and 300 bps.
ATB1 = Selects Bell 212A and 103 standards for communication at 1200
and 300 bps
Cn CARRIER CONTROL
Controls the transmit carrier. The FAX Modem is preset to turn
carrier on and off as necessary (the C1 option). The signal is on
when the FAX Modem is calling, Answering or connected to a remote
FAX Modem, and is off when it is not. The C0 option is NOT Valid.
ATC0 = Not permitted; returns ERROR result code.
ATC1 = Normal transmit carrier switching (preset).
ATD DIAL
This must be the last command on a command line. ATD causes the FAX
Modem to go off-hook, dial according to the parameters entered, and
attempt to establish a connection. If there are no parameters, then
the FAX Modem goes off-hook to originate FAX Modem without dialing a
number.
Punctuation may be used for clarity. Parentheses, hyphens and spaces
are ignored. If an invalid character is entered, that character and
all subsequent characters in the dial string are ignored. The FAX
Modem truncates dial strings to 40 characters.
The ATD Parameters are:
L Dials the last dial string that was dialed.
P Use Pulse Dialing. Placed at the end of the command string and
before the dial string. Causes the FAX Modem to pulse dial the
numbers.
T Use DTMF Dialing. Placed at the end of the command string and
before the dial string. Causes the FAX Modem to use DTMF tones
to dial.
R Reverse FAX Modem. Allows the FAX Modem to call an originate
only FAX Modem by Forcing the call into "Answer Mode" most
entered as the last character of the command string (just
before the <CR>).
! Hookflash. Causes the FAX Modem to go on-hook for 700
milliseconds and then off-hook.
@ Causes the FAX Modem to listen for 5 seconds of silence.
If a 5 second silence has not been detected within the period
specified in S7 (default = 30 seconds), the FAX Modem
disconnects and returns the "No ANSWER" result code. If it
detects a busy signal, it returns a "BUSY" result code. If
the 5 seconds of silence is detected, then the FAX Modem
continues dialing the dial string.
W Wait for Dial Tone Before Dialing. Causes the FAX Modem to
wait for a dial tone up to the period of time specified in
register S7 (default = 30 seconds), before dialing the numbers
that follow. If the FAX Modem detects a dial tone before the
given time delay, it continues to dial, otherwise, it goes
on-hook.
, Pause During Dial. Inserted between digits in a dial string.
Causes the FAX Modem to pause for the value given by register
S8 (default = 2 seconds), before dialing the next digit. This
delay can be used in place of the "Wait For Dial Tone Before
Dialing".
; Return To Command Mode After Dialing. Added to the and of a
dial string. Causes the FAX Modem to remain in the command
mode after it dials the digits preceding the command. This
allows the user to issue additional dial commands or dial
strings without overflowing the command buffer. The FAX
Modem looks for the carrier after the final dial command is
issued. "ATHn" abort this command.
^ Turn On Calling Tone. Turns on the periodic 1300 Hz calling
tone if originating the call. Calling tone is enabled only
on a call-by-call basis.
S=n Dial Stored Number Follows the dial command string. Causes
the FAX Modem to dial a telephone number previously stored in
directory location "n" using AT&Zn command.
The ATD command will be aborted in progress upon receipt of any
character from the DTE before completion of the handshake.
ATE COMMAND ECHO
Controls the echo of characters received by the FAX Modem from the
local DTE while the FAX Modem is in the command mode.
ATE0 = Inhibits the echoing of commands.
ATE1 = Enables the echoing of commands.
ATHn SWITCH-HOOK CONTROL
Applies to asynchronous only. If the user enters the command mode
from the data mode by issuing the escape sequence (+++), or as a
result of an ON-to-OFF transition of STR with the AT&D1 option in
effect, the user may cause the FAX Modem to on-hook (disconnect) by
issuing the ATH command.
ATHO = Causes the FAX Modem to go on-hook (hang-up).
ATH1 = If FAX Modem is on-hook FAX Modem goes off-hook, returns an
OK response and awaits further commands.
Returns the product code, returns the checksum of the firmware ROM,
or computers the checksum at the firmware ROM and reports it's error
status. The product code contains 3 digits. The checksum result
consists of three ASCII numeric characters followed by a carriage
return and a line feed. The error status is either OK or ERROR.
ATI0 = Reports the product code.
ATI1 = Reports the checksum computed on the firmware ROM.
ATI2 = Performs a checksum on the firmware ROM and indicates OK or
ERROR.
ATI3 = Reports firmware manufacturer identification and checksum.
ATI4 = Reports product capabilities.
ATLn SPEAKER VOLUME
Controls the internal speaker volume.
ATL0 = Selects low speaker volume.
ATL1 = Selects low speaker volume.
ATL2 = Selects medium speaker volume.
ATL3 = Selects high speaker volume.
ATMn SPEAKER CONTROL
Controls the internal speaker while the FAX Modem is receiving a
carrier signal or dialing. This command also enables or disables
the speaker.
ATM0 = Speaker is always off.
ATM1 = Speaker goes off while the FAX Modem is receiving a carrier
signal from a remote FAX Modem.
ATM2 = Speaker is always on.
ATM3 = Speaker goes off while the FAX Modem is receiving a carrier
signal from a remote FAX Modem and while the FAX Modem is
dialing.
ATNn MODULATION HANDSHAKE
This command can be used to assure that a connection is made only
at the specified speed. If leased line is selected, these commands
are ignored and the FAX Modem operates as it ATN0 were selected.
ATN0 = Requires that the speed of the connected be that specified
by the value held in S37, if S37=0, the speed of the
connection must match that at which the last AT command was
issued. If the selected speed, can be achieved using more
that, one communication standard (e.g. Bell 212A or CCITT
V.22 at 1200 bps except V.23), the FAX Modem also references
the selection mode with the ATB command.
ATN1 = Permits handshaking to occur at any speed supported by both
FAX Modems. Enables automode detection. The ATB command is
ignored in this mode and the FAX Modem attempts only CCITT
mode connections.
AT0n RETURN TO THE ON-LINE STATE
Applies to asynchronous only. If the user enters the command mode
from the data mode by issuing the escape sequence, or as a result
of an ON-to-OFF transition of DTR with the AT&D1 option in effect,
the user may return to the data mode without terminating a call by
issuing the AT0 command.
The command may also be used to force a retrain. If the FAX Modem
is on-hook, then the FAX Modem behaves as it went off-hook to
originate without actually taking the relay off-hook.
ATO0 = Causes the FAX Modem to return to the data mode.
ATO1 = Causes the FAX Modem to return to the data mode and initiate
a retrain when operating at 2400 bps.
Causes the FAX Modem to assume that all subsequent dial commands
are pulsed dialed. The user may omit the "P" from the dial strings.
ATQn RESULT CODE DISPLAY
Determines whether or not the FAX Modem sends the result codes to the
DTE. (See ATXn command).
ATQ0 = Allows the FAX Modem to send result codes to the DTE.
ATQ1 = Prohibits the FAX Modem from sending result codes to the DTE.
ATQ2 = FAX Modem returns result codes to the DTE when originating a
call; does not return result codes when answering a call.
ATSn? READING S REGISTERS
Reads the contents for the S register. All the S registers may be
read.
ATSn=x WRITING TO S REGISTERS
Writes the value of "x" to the specified S registers. All the
registers will return the OK response if "x" is a legal value,
however, some registers will not actually write the value anywhere.
These registers are S1, S13-S15, S17, S20-S24, and S27.
ATT SET TONE DIAL AS DEFAULT
Causes the FAX Modem to assume that all subsequent dial commands are
tone dialed. The user may omit the "T" from the dial string.
ATVn RESULT CODE FROM (MESSAGE CONTROL)
Selects whether the FAX Modem sends long form or short form result
codes to the local DTE. All responses are ASCII values. Long-form
(verbose) responses are preceded and terminated with both carriage
return and line feed control characters. Short-form (numeric)
responses are only terminated with a carriage return control
character. (See ATXn command).
ATV0 = Allows short-form (numeric) result codes to be sent.
ATV1 = Allows long-form (verbose) result codes to be sent.
ATWn NEGOTIATION PROGRESS REPORTING
An additional set of result codes be enabled with the W command to
report progress of the negotiation phase of error-correction mode.
These codes report the carrier speed (300 bps-2400 bps) and the
error-correction protocol. These messages can also be reported in
either numeric or verbose form. For example, both 77 and PROTOCOL:
LAP-M indicates that the error correction protocol is LAP-M (see
ATXn command).
If the error-corrections link is negotiated and a connection is
made, the appropriate CONNECT XXXX message is reported.
When in error-correction mode, the CARRIER XXXX message may indicate
one speed, while the CONNECT XXXX message reports another.
ATW0 = Error-correction call progress NOT reported.
ATW1 = Error-correction call progress reported.
ATW2 = Error-correction call progress not reported. CONNECT XXXX
message reports DCE speed.
Continued on Faxback Document # 5799
(SMC/all-06/06/94)