SIERRA AT COMMANDS
AT Commands
Introduction
The Sierra Modem uses the standard Hayes AT command set. The
AT command set was developed by Hayes Microcomputer Products,
Inc.
In addition to normal modem commands, it also supports special AT
commands for Fax and MNP functions.
The commands are broken down by type of command, with the command
and their options explained. They should be issued in upper case
(capital) letters. Unless otherwise specified, all commands begin
with AT (Attention) and end with a carriage return.
Defaults
Most commands have a default setting. In other words, a setting
that is configured in the hardware of the modem. The defaults
will be indicated in the explanation of the commands.
The default settings can be changed by entering the appropriate
number or symbol after the command. This new setting will stay
in effect until it is changed by issuing another command, or
until the power is turned off. When the power is turned off, all
settings are returned to their hardware configuration.
Keep in mind that some communications software will change some
settings when you enter the program, and will not necessarily
reset them when you exit the program.
AT, although not strictly a command as defined here, is used to
signal that what follows is a command. When AT is entered, the
previous command is cleared from the memory of the modem.
Escape Sequence Command
The escape sequence command can be issued while online in order
to allow the modem to return to the command mode without hanging
up.
The normal escape sequence is three plus signs ( + ). This code
can be changed by changing the value of the S2 register. S-
Registers are memory locations of the modem.
The three +'s should be typed in quick succession. After typing
them in, you must pause long enough for the guard time to elapse
before typing anything else. The default guard time is one
second. This can be changed by changing the value of the S12
register.
You must pause after typing in the escape sequence code so that
the modem knows that it is a command, and not simply data being
transmitted.
General Commands
These commands are used to change certain settings that, once set,
will be generally used at those same settings.
B Bell/CCITT
B0 Instructs the modem to operate in CCITT V.22 mode
(1200 bps) or V.21 mode (300 bps).
B1 Instructs the modem to operate in Bell 212A mode
(1200 BPS) or Bell 103 mode (300 bps) This is the
default setting.
E Command Echo
E0 Disables echoing of commands to the screen.
E1 Enables echoing of commands to the screen. This is
the default setting.
L Speaker Volume (of modem)
L0 Minimum volume.
L1 Low volume.
L2 Medium volume. This is the default setting.
L3 Loud volume.
M Speaker Control (of modem)
M0 This command disables the modem speaker.
M1 This command turns on the modem speaker, and then
turns it off when a connection has been established.
This is the default setting.
M2 This command instructs the modem speaker to stay on at
all times.
M3 This command disables the modem speaker while dialing,
and also after a connection has been established.
Q Quiet
Q0 This command enables result codes to be issued to the
screen. This is the default setting.
Q1 This command disables the issuing of result codes to the
screen.
S S-Registers
S= This command is used to set a value to an S-register. S-
Registers are explained in detail in Chapter Six.
S? This command is used to inquire of the value of an S-
register. S-Registers are explained in Chapter Six.
V Result Code Type
V0 This command instructs the modem to display result
codes in the numeric (terse) format.
V1 This command instructs the modem to display result
codes in the verbal format. This is the default
setting.
X Result Code Sets
X0 This command specifies that the modem return the
minimum set of result codes.
X1 This command is similar to the X0 command. It adds
the speed when a connection has been established, such
as CONNECT 1200. Also, this command instructs the modem
not to wait for a dial tone before beginning to dial.
X2 This command is similar to the X1 command, but will
instruct the modem to wait for a dial tone before
beginning to dial.
X3 This command is similar to X1, but adds call progress
messages and tone detection. Like X1, it instructs the
modem not to wait for a dial tone before beginning to
dial.
X4 This command is like X3, but instructs the modem to wait
for a dial tone before beginning to dial. This is the
default setting.
&J Telephone Jack Selection
&J0 This command selects an RJ11 type of telephone jack.
This is the default setting.
&J1 This command selects an RJ12 type of telephone jack.
&L Line Selection
&L0 This command selects a dialup telephone line. This is the
default setting.
&L1 This command selects a leased line as the type of
telephone line to be used.
&M Async/Sync Mode Selection
&M0 This command selects the asynchronous mode, which is
used for modem communications. This is the default
setting.
&M1 This command selects synchronous mode 1.
&M2 This command selects synchronous mode 2.
&M3 This command selects synchronous mode 3.
&Y Select Profile
This command is only available if you have the optional non-volatile
RAM installed.
&Y0 This is the default setting. It will select the default,
or main, profile.
&Y1 This command will select the next profile from the non-
volatile RAM.
Immediate Action Commands
These commands perform a specific action at the time they are
issued. They do not change any settings, rather, the command is
issued and executed only.
A Answer
This command sets the modem to answer a call. Commands issued
after the A on the command line will not be executed.
A/ Repeat Command
This command is the only one that is not preceded by AT. When it
is issued, it will repeat the last command that was sent to the
modem.
D Dial
This command instructs the modem to go off hook and dial the
numbers that follow. This command can be followed by commands
in the Dial Modifier section shown later in this chapter.
H Switch Hook Control
H0 Instructs the modem to drop the line.
H1 The command instructs the modem to seize the line.
Normally, only H0 is used, and modem is allowed to
control the switch hook.
O Return to Online
This command switches the modem from command mode to online
mode. It instructs the modem to go on line without dialing.
Z Reset
This command resets all values to their default settings. It
should respond with OK. You should wait 1/2 second before
sending any other commands.
&Zn Store Telephone Number
This command is only available if you have the optional non-volatile
RAM installed. It stores the telephone number given in the non-
volatile RAM of the modem. The maximum number of characters
that can be stored are 33. Only valid digits and dial modifiers are
stored. Others are ignored.
&Z=### Stores ### in location 0
&Zn= ### Stores ### in location n where n is 1 -4.
Dial Modifiers
When dialing a phone number, the D (Dial) command can be modified
to dial in a particular way. This section lists the commands that can
be used after the D (Dial) command to modify it.
P Pulse Dial
Instructs the modem to dial the phone using pulse (rotary)
dialing.
S=n Recalls the dial string stored in location n
T Touch Tone Dial
Instructs the modem to dial the phone using touch tone dialing.
W Wait for Dial Tone
This command instructs the modem to wait a specified period of time
for a dial tone. The default time is 30 seconds. If the modem does
not detect a dial tone in the specified period of time, it will hang up.
The message NO DIAL TONE will be displayed.
, Delay
This command instructs the modem to pause for a specified period of
time before processing the next command. The default time is 2
seconds. This can be modified by setting the S8 register.
@ Quiet Answer
This command tell the modem to wait a specific amount of time for
one or more rings, followed by a 5 second pause. The next command
on the line will then be executed. You can use this command to
establish a connection with a system that does not have a dial tone.
! Initiate Hook Flash
This command sends a 1/2 second hook flash.
; Return to Command State
This command instructs the modem to return to the command state
at the end of the command line. It can be used for originating
voice calls, and can be placed anywhere on the command line.
International Commands
These commands change certain settings which may be required if
you are using the modem out of the United States.
&G Guard Tones
&G0 This command uses no guard tones. This is commonly
used in the United States.
&G1 This command selects a guard tone of 550 Hz. This is the
default setting.
&G2 This command selects a guard tone of 1800 Hz.
&P Make/Break Pulse Ratio
&P0 This command selects a make/break ratio of 39:61
without adaptive dialing. This is used in the United
States, and is the default setting.
&P1 This command selects a make/break ratio of 33:67
without adaptive dialing. It is used in the United
Kingdom and Hong Kong.
Self Test and Diagnostics
These commands are used to perform self-tests and diagnostic
routines on the modem.
I Identity
I0 Returns the product code.
I1 Returns 000.
I2 Returns OK.
I3 Returns modem code revision number
I4 Returns the modem configuration settings.
&T Test
&T0 This command terminates any test in progress.
&T1 This command executes the local analog loopback test.
&T3 This command executes the local digital loopback test.
&T4 This command enables the modem to accept a request
from a remote modem for a digital loopback test.
&T5 This command instructs the modem not to accept a
request from a remote modem for a digital loopback
test.
&T6 This command begins a remote digital loopback test.
&T7 This command begins a remote digital loopback test with
a self test.
&T8 This command begins a remote analog loopback test with
a self test.
Async Only Commands
These commands can only be used in the asynchronous (modem)
mode. They cannot be used in the synchronous (Fax) mode.
Y Long Space Disconnect
Y0 Turns off the long space disconnect.
Y1 Turns on the long space disconnect. The modem will
disconnect and hang up after any break of more than
1.6 seconds. This is the default setting.
&C DCD (Data Carrier Detect) Options
&C0 This command forces DCD to be on.
&C1 This command instructs DCD to follow the carrier.
This is the default setting.
&D DTR (Data Terminal Ready) Options
&D0 This command instructs the modem to ignore DTR.
This is the default setting
&D1 This command causes the modem to revert to the
command mode during the on-to-off transition of DTR.
&D2 This command causes the modem to go back on-hook and
disable auto-answer during the on-to-off transition of
DTR.
&D3 Causes the modem to reset with the on-to-off transition
of DTR.
&S DSR (Data Set Ready) Options
&S0 This command causes DSR to be always on.
&S1 This command causes DSR to follow the carrier.
Synchronous Only Commands
These commands can only be used in the synchronous mode, not the
asynchronous (modem) mode.
&R RTS-CTS (Ready to Send/Clear to Send)
&R0 This command instructs CTS to track RTS.
&R1 This command forces CTS to be true whenever the
modem is in the data mode.
&X Synchronous Mode Transmit Clock
&X0 This command selects the modem as the source for the
synchronous mode transmit clock.
&X1 This command selects DTE (data terminal equipment) as
the source for the synchronous mode transmit clock.
&X2 This command selects the slave (from the receive clock)
as the source for the synchronous mode transmit clock.
&X3 This command is the same as the &X2 command shown
above. It is the default setting.
FAX Commands
The commands that follow are a special subset of the AT command
set. They are used for FAX transmission only. All of the extended
commands in this section must be preceded indvidually by a plus
sign ( + ). The commands themselves must be preceded by AT, and
end with a carriage return. As with the other AT commands, they
should be typed in upper case (capital) letters.
Once the modem is put into the Fax mode, it will remain there
until a +F0 command is received, or a call disconnect frame is
received.
FAX Extended Command Set
Note: The format of these commands reflects the original
proposals presented at the TIA 29.2 committee at the time Seirra
introduced the Sendfax product. The "+" sign prefix was changed
to "#" to avoid conflict with the evolving standard. Sierra is
actively involved in developing the new standard command set for
Class 2 fax and data modems and will offer a compatible firmware
version as soon as the standard is stabilised. This is expected
to be in the Spring of 1990.
#B Speed Control
#B4 This command selects an initial Fax transmission speed
of 2400 bps.
#B5 This command selects an initial Fax transmission speed
of 4800 bps.
#B6 This command selects an initial Fax transmission speed
of 7200 bps.
#B7 This command selects an initial Fax transmission speed
of 9600 bps.
#E Received Data Display Format
#E0 This command disables the display of the received HDLC
frames.
#E1 This command will display the received frames in a binary
format.
#E2 This command will display the received frames in an
ASCII hex format.
#F Fax/Modem Mode Selection
#F0 This command put the modem into the normal modem
(asychronous) mode.
#F1 This command is used to put the modem into the Fax
mode.
#K DTE Flow Control
#K0 This command will disable flow control.
#K3 This command will select CTS flow control.
#K4 This command will select XON/XOFF flow control.
#P Number of Pages to be Transmitted
This command is used to transmit how many pages will be sent.
The syntax is #Pn, where n equals the number of pages to be sent.
The number of pages can be from 1 to 255.
#R Resolution Control
#R0 This command will send documents with normal
resolution.
#R1 This command will send documents with fine resolution.
#T Test Modes
#T0 This command will end the test mode.
#T1 This command will begin the test mode. This test will
dial a remote Fax machine and automatically send a
message that is stored on an EPROM.