| |
Often modem problems can be reduced
or eliminated by using the proper modem initialization string.
Unfortunately, there are literally hundreds of variations of the
"Hayes AT Command Set" and "s-register" settings.
In general read your modem documentation
carefully, and don't put more into the string than is
necessary. As an example, with a Supra on a PC, the string AT&F2 is an
adequate initialization string for many users; for a USR modem, AT&F1 is
frequently adequate.
These two examples demonstrate using a "template" --
a pre-defined set of modem initialization codes which can be invoked with
a single command. Most modems contain one or more default templates for
different common situations, and also let you save your own custom
"default" string. Many users use an init string that calls up a
template, and then invokes a few custom commands to tailor the defaults.
Read your modem docs to see if one of your modem manufacturer's default
templates will work for you (at least as a starting point).
The following are all the commands in the Hayes Extended Command Set.
These are generally supported by all modems, in addition to each modem's
specific command set.
For more on modem init strings for specific types
of modems, see the Modem Resource Page.
|
|
| |
| Command | Function |
| AT |
Command line prefix. The ATtention command
precedes all other commans listed below except
for A/ and the escape code. For example, the
command DT would be typed ATDT.
|
| A/ |
Repeat last command(not to be preceded by AT)
|
| A |
The modem is set to answer mode and goes
offhook immediately. Answer without waiting
for ring.
|
| Bn |
Bell mode - set 1200 bps protocol compatibility
Selects V.22 or Bell 212A in the 1200bps mode.
n=0, CCITT V.22 with 2100Hz Answer Back Tone.
n=1, Bell 212A with 2225Hz Answer Back Tone.
|
| Cn |
Carrier state: n=0, OFF
n=1, ON
ex. C1 = carrier state on
|
| Dn |
Dial telephone number. Dial the number immedi-
ately following this command, where n is the
number combined with other dial subcommands as
shown below. Any combination of the subcommands
listed below may be strung together to perform
the desired dialing sequence. The number is
dialed in the call progress or blind mode
depending on register S11.
| Dial Subcommand | Function |
| T |
Touch Tone Dialing |
| P |
Pulse dialing (some modems use by
default to Pulse if T or P not used |
| R |
Reverse mode. Puts modem in answer
mode immediately after dialing.
Use answer frequencies when origi-
nating a call. |
| S=n |
Dial a stored number. The numbers
are stored in the registers of the
microcontroller.
n=0,1,2,3 - stored number that has
been previously stored
in non-volatile RAM,
using &Zn command.
(see &Zn command below) |
| W |
Wait (for seconds dial or access
tone). Wait for a continuous tone
before dialing the next number.
Useful for dialing MCI or Sprint.
The modem waits S7 seconds (see
Appendix B about registers) for the
tone. If the tone is not heard,
BUSY or NO DIALTONE result code is
issued. |
| @ |
Wait for a "quiet answer" - one or
more rings followed by 5 seconds of
silence - for the length of time
defined by register S7. (see App.B) |
| , |
(comma) - Pause (a delay in dialing
sequence). Pause the length of time
specified by S8 (default time = 2s)
Each comma equals the pause length
specified. You may use as many
commas as you like.
ex. To disable call waiting in most areas use, *70,,413-9111 to connect to
UIC
|
| ! |
Flash(on-hook for 1/2 second). This
character can be used to go temporarily on-hook in order to get a
new dialtone. |
| ; |
Return to command mode after dialing. This command can only be
placed at the end of a dial command |
0-9
#
*
ABCD |
Digits and characters that may be
used in dialing. # * and ABCD may
only be used when tone dialing. |
| En |
Echo modem command. Determines whether the mo-
dem echoes the data received in the command
mode back to the host.
n=0, echo OFF ( or NO)
n=1, echo ON ( or YES)
ex. E1 = echoing turned on
|
| Fn |
Full or half duplex operation.
n=0, half duplex
n=1, full duplex
ex. F1 = full duplex operation
|
| Hn |
Hook. Controls the modem on/off hook relay
n=0, on hook(disconnected or hang up)
n=1, off hook |
| In |
Request product code and ROM checksum. Return
product ID/checksum.
n=0, Returns product ID. Modem sends its
3-digit product code.
n=1, Performs checksum, return checksum. Requ-
est numeric checksum of firmware ROM.
n=2, Performs checksum, returns result code.
Request OK or ERROR state of ROM checksum.
n=3, returns ROM part # and revison level. |
| Ln |
Loudness of speaker volume
n=0, low
n=1, low
n=2, medium
n=3, high
ex. L2 = this will give you the preferable medium setting |
| Mn |
Speaker control. Mode of speaker operation.
n=0, speaker always OFF
n=1, speaker ON when phone is off-hook
speaker OFF when Carrier Detected
n=2, speaker always ON
n=3, speaker ON after dialing until Carrier
Detected. Disable speaker when modem
receives a carrier signal while modem is
dialing.
ex. M1 = good way to listen in on a conversation without ever being
noticed |
| On |
On-line state. Puts modem in the online data
mode.
n=0, Online. Modem returns to the on-line state
n=1, Online with equalizer retrain sequence.
Modem returns on-line and retrains equali-
zer. (2400 bps mode only) |
| Qn |
Quiet command for result codes. Result codes
ON/OFF.
n=0, codes are sent
n=1, codes are NOT sent |
| Sn? |
Reads the contents of status register Sn.
Display value of S-register n.
ex. S7 contain how many seconds to wait after a ring |
| Sn=x |
S-register command. This command may be used to
modify an S register of the modem. It assigns
a value X to the status register N. They may
be reset to the default values by issuing an
'&F' or 'Z' command. See Appendix B for a list
of S registers.
n=S-register number
x=value to set register to |
| Vn |
Sets result code format. Verbose mode for
result codes.
n=0, use digits(numeric)
n=1, use words |
| Xn |
Sets dialing mode, result code format for dial
command. Enable extended result code and mode
setting.
n=0, basic(300bps).Dialtone and busy signal
not recognized (blind dialing). Result
codes 0-4 enabled.
n=1, extended(no dialtone or busy signal detec-
tion). Dialtone and busy signal not recog-
nized (blind dialing). Result codes 0-5
and 100 enabled.
n=2, extended(detects dialtone but not busy
signals). Dialtone detected. Busy signal
not detected. Result codes 0-6 and 10
enabled.
n=3, extended(no dialtone detect but detects
busies). Busy signal detected. Dialtone
not detected. Result codes 0-5,7 and 10
enabled.
n=4, extended(detects both dialtones and busies |
| Yn |
Long Space Disconnect Option
n=0, disabled
n=1, enabled; disconnects after receiving
1.6 sec break. |
| Z |
Causes a software reset with registers set to
default values. Fetch configuration profile
from non-volatile memory.
Basically resets the modem.
|
| &Cn |
Data Carrier Detect handling. Enables DCD.
n=0, DCD always on. Modem keeps DCD (RS-232
pin 8) always on.
n=1, DCD set by modem when remote carrier
detected. DCD tracks data carrier detected
by modem. |
| &Dn |
Data Terminal Ready handling. Enables DTR.
DTR ON/OFF time as specified by S25.
n=0, modem ignores DTR line (RS-232 pin 20)
n=1, switches to command mode when DTR goes off
modem assumes asynch command state when
DTR goes off.
n=2, same as n=1. Also hangs up, disables auto
answer. DTR off switches modem off hook,
out of answer mode and back to command
state.
n=3, initializes modem when DTR goes off.
DTR switching off initialized modem. |
| &F |
Fetch factory configuration profile from ROM.
Sets values for S Registers and Commands to
factory default. Same as powerup reset. |
| &Gn |
Guard tone selection (used only when in CCITT
modes)
n=0, no guard tones
n=1, 550 Hz guard tone
n=2, 1800 Hz guard tone
This command need never be used when communica-
ting over U.S. phone lines. Outside the U.S.
the modem may need to generate an additional
tone, along with its carrier, to disable echo
suppressors in the central office. The guard
tone varies by country. |
| &Jn |
Telephone jack selection
n=0, RJ-11/RJ-41S/RJ-45S
n=1, RJ-12/RJ-13 |
| &ln |
Leased-line or dialup line selection
n=0, dialup operation
n=1, leased-line
You'll almost always use &l0
|
| &Mn |
Asynchronous/Synchronous communication mode
selection
n=0, asynchronous
n=1, synchronous mode 1 -async dialing, then
switch to synchronous operation
n=2, synchronous mode 2 -stored number dialing
n=3, synchronous mode 3 -manual dialing |
| &Pn |
Pulse dial make/break pulse length selection
n=0, 39% make,61% break(US and Canada standard)
n=1, 33% make,67% break |
| &Qn |
Communications Mode Option
| Idle State | On-Line State |
| n=0 | Normal | Asynchronous |
| n=1 | Normal | Reserved |
| n=2 | Dial when DTR=1
Hangup when DTR=0 | Reserved |
| n=3 | Task/data, DTR=0/1 | Reserved |
|
|
|
| &Rn |
Requiest to Send/Clear to Send handling
(sync mode only)
n=0, CTS (RS-232 pin 5) tracks RTS (pin4)
n=1, modem ignores RTS and turns CTS on when
ready to receive synchronous data |
| &Sn |
Data Set Ready handling. Controls DSR. DRS ON
indicates that the modem is connected to a
communication channel and is ready.
n=0, DSR is always ON. Modem forces DSR ON
whenever modem is turned on
n=1, DSR (RS-232 pin 6) operates accong to EIA
specs. DSR turned ON at start of hand-
shaking, off in test mode, idle state, or
when carrier is lost |
| &Tn |
Control Test mode(not available in 300bps mode)
n=0, terminate any test in progress when last
command on a line. Ends current test and
returns to command mode
n=1, initiates local analog loopback test
n=3, initiate local digital loopback test
n=4, conditions modem to perform remote digital
loopback when requested by another modem
n=5, prohibits remote digital loopback
n=6, initiates remote digital loopback with
another modem
n=7, initiates remote digital loopback with
self-test
n=8, initiates local analog loopback with
self-test |
| &V |
Displays active configuration profiles (S Re-
gister settings, commands, and telephone
numbers. Inputs from DTE are ignored while
this information is being sent. |
| &Wn |
Write active configuration profile to memory.
Sends and stores acceptable values for certain
commands and S Registers to non-volatile RAM.
The last DTE speed and parity are also stored
Stored values are used on power-up or hard
reset.
n=0, store active profile in location 0
n=1, store active profile in location 1 |
| &Xn |
Select synchronous transmit clock source
(sync mode only)
n=0, Internal clock, modem generates timing
and sends through pin 15
n=1, modem's host computer generates timing
and sends it to modem on pin 24, which
modem routes to pin 15.
n=2, Receive clock, modem derives timing from
incoming signal and supplies it to pin 15 |
| &Yn |
Select Stored Profile on Power Up Option
n=0, Select profile 0 on power up or hard reset
n=1, Select profile 1 on power up or hard reset
See, the &Wn command for particular commands
and S Registers stored. The selected &Y command
survives a power outage. |
| &Zn |
Stores telephone number.
n=string of digits compatible with Dial command |
|
|
|
