ARCHIVED: What AT commands can I use with a Hayes compatible modem?
This content has been archived, and is no longer maintained by Indiana University. Information here may no longer be accurate, and links may no longer be available or reliable.
The following is a list of Hayes compatible AT commands and S registers:
Command | Description |
---|---|
AT |
Attention command; defines speed, precedes
common line
|
A/ |
Re-executes last command line if
modem hasn't made connection
|
A |
Modem goes off-hook in answer mode
|
B0 |
Sets CCIT V.22 operation when at 1200bps
|
B1 |
Sets Bell 212A operation when at 1200bps
|
C0 |
Sets transmit carrier off |
C1 |
Sets transmit carrier on |
D |
Dial number following D in command line
|
E0 |
Modem doesn't echo commands back to terminal
|
E1 |
Modem echoes commands back to terminal
|
F0 |
Sets modem to half duplex |
F1 |
Sets modem to full duplex |
H0 |
Modem goes on-hook (hangs up) |
H1 |
Enables switchhook and auxiliary relay
|
I0 |
Displays product Identification Code
|
I1 |
Performs checksum on firmware
ROM; displays value
|
I2 |
Performs checksum on firmware
ROM; returns "Error" or "OK"
|
I3 |
Returns make, model, firmware of modem;
e.g., "U.S. Robotics 56K FAX EXT V5.1.4"
|
L1 |
Speaker volume low |
L2 |
Speaker volume medium |
L3 |
Speaker volume high |
M0 |
Speaker off |
M1 |
Speaker on until carrier detected
|
M2 |
Speaker always on |
M3 |
Speaker on until carrier detected except
when dialing
|
O0 |
Return to online |
O1 |
Return to online with retrain |
P |
Pulse (for rotary [dial] telephone service)
|
Q0 |
Modem returns result codes |
Q1 |
Modem doesn't display result codes
|
Sr=n |
Set S register r to value n |
Sr? |
Display S register contents |
T |
Tone (for touch-tone telephone service)
|
V0 |
Short numeric result codes |
V1 |
Full result codes |
X0 |
CONNECT; result codes enabled |
X1 |
CONNECT BBBB; result codes enabled, blind
dial, busy signal not detected
|
X2 |
Modem waits for dial tone before dialing,
all CONNECT BBB result codes enabled, busy signal not detected
|
X3 |
Modem blind dials, all CONNECT BBBB results
codes enabled, modem sends BUSY if busy signal detected
|
X4 |
Modem waits for dial tone before dialing,
all CONNECT BBBB results codes enabled, modem sends BUSY if busy
signal is detected
|
Y0 |
Long space disconnect disabled
|
Y1 |
Long space disconnect enabled |
Z |
Load stored profile configuration
|
&C0 |
DCD always ON |
&C1 |
DCD ON if data carrier present
|
&D0 |
Modem ignores DTR |
&D1 |
Modem assumes command state with
ON-to-OFF transition on DTR
|
&D2 |
Modem hangs up, assumes command state,
disables auto answer upon detecting ON-to-OFF transition on DTR
|
&D3 |
Modem assumes initialization state with
ON-to-OFF transition to DTR
|
&F |
Load factory profile configuration
|
&G0 |
No guard tone |
&G1 |
550Hz guard tone |
&G2 |
1800Hz guard tone |
&L0 |
Selects dial-up line |
&L1 |
Selects leased line |
&P0 |
Pulse dial make/break ratio 39/61
(USA/Canada)
|
&P1 |
Pulse dial make/break ratio 33/67
(UK/HK)
|
&R0 |
CTS follows RTS |
&R1 |
Modem ignores RTS; CTS always on
|
&S0 |
DSR always ON |
&S1 |
DSR compatible with EIA RS-232C
|
&T0 |
Ends test in progress |
&T1 |
Initiate Local Analog Loopback Test
|
&T2 |
RESERVED |
&T3 |
Initiate Digital Loopback |
&T4 |
Grants request from remote modem for
Digital Loopback
|
&T5 |
Denies request from remote modem for
Digital Loopback
|
&T6 |
Initiate Remote Digital Loopback Test
|
&T7 |
Initiate Remote Digital Loopback Test
with Self Test
|
&T8 |
Initiate Local Analog Loopback Test
with Self Test
|
&W |
Write present profile configuration to
nonvolatile RAM
|
&Z |
Stores a phone number in nonvolatile RAM
|
S registers
Command | Description | Duration | Default |
---|---|---|---|
S0 |
Ring to answer | 0-255 rings | 0 |
S1 |
Number of rings | 0-255 rings | 0 |
S2 |
Escape character | 0-127 ASCII | 43(+) |
S3 |
Carriage Return | 0-127 ASCII | 13(CR) |
S4 |
Line Feed | 0-127 ASCII | 10(LF) |
S5 |
Back Space | 0-127 ASCII | 8(BS) |
S6 |
Wait for dial tone | 2-255 seconds | 2 |
S7 |
Wait for carrier | 1-255 seconds | 30 |
S8 |
Comma pause time | 0-255 seconds | 2 |
S9 |
Carrier response | 1-255 .1 seconds | 6 |
S10 |
Carrier loss delay | 1-255 .1 seconds | 7 |
S11 |
Tone duration | 50-255 mseconds | 70 |
S12 |
Escape guard time | 20-255 .02 seconds | 50 |
S13 |
Bitmapped UART status register
|
||
S14 |
Bitmapped Option register | ||
S15 |
Bitmapped Flag register | ||
S16 |
Bitmapped Test options | ||
S17 |
RESERVED | ||
S18 |
Test times | 1-255 seconds | 0 |
S19 |
RESERVED | ||
S20 |
RESERVED | ||
S21 |
Bitmapped | ||
S22 |
Bitmapped | ||
S23 |
Bitmapped | ||
S24 |
RESERVED | ||
S25 |
Delay to DTR | 0-255 .01 seconds | 5 |
S26 |
RTS to CTS delay | 0-255 .01 seconds | 1 |
This is document aaqc in the Knowledge Base.
Last modified on 2018-01-18 09:01:15.