Online HelpPC 2.10 Quick Reference Utility Copyright 1991 David Jurgens
Hayes Command Set / Register Formats
+++ standard escape sequence (see S2 below)
Comma standard pause character (see S8 below)
AT standard attention sequence
ATA force immediate answer
ATC0 transmitter off
ATC1 transmitter on
ATD dial (ATD number)
ATDP pulse dial (ATDP number)
ATDT tone dial (ATDT number)
ATE0 disable local character echo
ATE1 enable local character echo
ATF0 Half Duplex (modem echoes characters)
ATF1 Full Duplex (modem does not echo characters)
ATH0 force line on hook
ATH1 force line off hook
ATH2 force line special off hook (used for HAM radio)
ATI0 request product code, formatted PPR, PP=prod., R=rev.
ATI1 request ROM check sum
ATL1 speaker volume low (modem specific)
ATL2 speaker volume medium (modem specific)
ATL3 speaker volume high (modem specific)
ATM0 speaker always off
ATM1 speaker on except while carrier present
ATM2 speaker always on
ATM3 speaker on except while dialing and carrier present
ATO force modem into on-line state
ATP sets modem to default pulse dial
ATQ0 modem returns result codes
ATQ1 modem does not return result codes
ATR sets modem to answer mode after dialing out
ATSn where Sn is S register number 'n' (see registers below)
ATT sets modem to default tone dial
ATV0 send numeric codes
ATV1 send word result codes
ATX0 basic result code set "CONNECT", no dial tone detect
ATX1 extended result code set "CONNECT 1200", no dialtone detect
ATX2 wait for dial tone, extended result codes
ATX3 detect busy signal, extended result codes
ATX4 wait for dial tone, detect busy, extended result codes
ATZ reset to power up condition
Hayes 2400 Compatible Modem Commands
ATB0 CCITT V.22 at 1200 bps
ATB1 BELL 212A at 1200 bps
AT&C DCD always on
AT&C1 DCD on while carrier present
AT&D DTR ignored
AT&D1 DTR fail disconnect enabled
AT&D2 DTR fail disconnect enabled (auto answer off)
AT&D3 DTR fail disconnect enabled (reset modem)
AT&F restore to factory configuration
AT&G no guard tone
AT&G1 550 Hz guard tone
AT&G2 1800 Hz guard tone
AT&J RJ11/RJ41S/RJ45 jack
AT&J2 RJ12/RJ13 jack
AT&L regular phone line
AT&L1 leased line
AT&M async operation
AT&M1 async/sync operation
AT&M2 sync auto dial
AT&M3 sync manual dial
AT&P 39/61 pulse make/break ratio
AT&P1 33/67 pulse make/break ratio
AT&T4 grant RDL test request
AT&T5 deny RDL test request
AT&W write current registers to non-volatile memory
AT&X sync clock internal
AT&X1 sync clock external
AT&X2 sync clock slaved
AT&Z store dial command line
Hayes Compatible Modem Registers
Not all modems support all of these registers and some modems have
registers other than those listed here. Also note, some are read only.
to set a register use: AT Sr=## (cr)
to read the register: AT Sr? (cr)
Where "r" is the register and (cr) is a carriage return
The following represent conventions used in the tables below:
() indicates defaults for Smartmodem 1200
** indicates possible inconsistencies across modems
Reg Values Register function
S0 0-255 ring to answer on (0=don't answer)
S1 0-255 ring count (clear after 8 sec) (read only)
S2 0-255 escape char, normally "+", 128-255 disable escape
S3 0-127 end of line character (0x0D/CR)
S4 0-127 line feed character (0x0A/LF)
S5 0-32,127 backspace character (0x08/BS)
S6 2-255 pause before dialing in seconds (2)
S7 1-255 wait for carrier in seconds (30)
S8 0-255 pause for comma in dial string in seconds (2)
S9 1-255 carrier detect response time in 1/10 second (6)
S10 1-255 carrier loss delay in 1/10 second, 255=ignore CD (7)
S11 50-255 touch tone dial speed, in milliseconds (70)
S12 20-255 escape guard time, in 1/50 second,0=no delay (50)
│7│6│5│4│3│2│1│0│ S13 power up async data format
│ │ │ │ │ │ │ └──── unused
│ │ │ │ │ │ └───── result code, 0=basic, 1=extended
│ │ │ │ │ └────── parity, 0=disabled, 1=enabled
│ │ │ │ └─────── parity, 0=odd ,1=even
│ │ │ └──────── data bits, 0=7 bits, 1=8 bits
│ │ └───────── undefined
│ └────────── buffer ovfw flag, 0=disabled,1=enabled
└─────────── 8th bit, 0=space,1=mark (8 bit only)
│7│6│5│4│3│2│1│0│ S14 option register status data format
│ │ │ │ │ │ │ └──── unused **
│ │ │ │ │ │ └───── local echo, 0=disabled, 1=enabled
│ │ │ │ │ └────── result codes, 0=enabled,1=disabled
│ │ │ │ └─────── result codes, 0=numeric,1=word
│ │ │ └──────── command recognition, 0=enable,1=disable
│ │ └───────── dial method, 0=touch tone, 1=pulse
│ └────────── unused **
└─────────── 0=answer, 1=originate **
S15 flag register **
│7│6│5│4│3│2│1│0│ S16 test status
│ │ │ │ │ │ │ └──── analog loop, 0=inactive, 1=active
│ │ │ │ │ │ └───── unused
│ │ │ │ │ └────── digital loop, 0=inactive, 1=active
│ │ │ │ └─────── remote req digital loop,0=inact.,1=active
│ │ │ └──────── remote digital loop,0=inact.,1=active
│ │ └───────── self test RDL, 0=inactive, 1=active
│ └────────── self test analog loop,0=inactive,1=active
└─────────── unused
S18 0-255 remote test timer in seconds
│7│6│5│4│3│2│1│0│ S21 option status
│ │ │ │ │ │ │ └──── jack type, 0=RJ11,RJ41,RJ45,1=RJ12,RJ13
│ │ │ │ │ │ └───── unused
│ │ │ │ │ └────── CTS state, 0=follows RTS, 1=forced on
│ │ │ └─┴─────── DTR modem behavior (see below)
│ │ └────────── DCD, 0=forced on, 1=follows carrier
│ └─────────── DSR, 0=forced on, 1=behaves normally
└──────────── long space disconnect,0=disabled,1=enabled
Bits
43 DTR Modem Behavior Bits
00 ignore DTR
01 assume command state when DTR drops
10 assume command state and disable auto-answer when DTR drops
11 reset when DTR drops
│7│6│5│4│3│2│1│0│ S22 option status
│ │ │ │ │ │ └─┴──── speaker volume, 01=low,10=med,11=high
│ │ │ │ └─┴─────── speaker setting (see below)
│ └─┴─┴────────── X command in effect
└─────────────── make/break ratio, 0=39/61, 1=33/67
Bits
32 S22 Speaker Setting
00 speaker always off
01 speaker on until carrier detected
10 speaker always on
11 speaker off during dialing, then on until CD
Bits
654 S22 X Command in Effect
100 X1 command in effect
101 X2 command in effect
110 X3 command in effect
111 X4 command in effect
│7│6│5│4│3│2│1│0│ S23 option status
│ │ │ │ │ │ │ └──── remote dig.loop request,0=denied,1=ok
│ │ │ │ │ └─┴───── baud rate (see table)
│ │ │ │ └──────── unused
│ │ └─┴───────── parity (see table)
└─┴──────────── guard tone setting
Bits
21 S23 Baud Rate Table
00 0-300 bps
01 600 bps
10 1200 bps
11 2400 bps
Bits
54 S23 Parity Setting
00 even parity
01 parity bit always 0
10 odd parity
11 parity bit always 1
Bits
76 S23 Guard Tone Setting
00 no guard tones
01 550 hz guard tone
10 1800 hz guard tone
S25 0-255 DTR detect delay in seconds (5)
S26 0-255 RTS to CTS delay in milliseconds (1)
│7│6│5│4│3│2│1│0│ S27 option status
│ │ │ │ │ │ └─┴──── synch/async mode (see table)
│ │ │ │ │ └─────── phone line, 0= public, 1=leased
│ │ │ │ └──────── unused
│ │ └─┴───────── clock type (see table)
│ └──────────── protocol, 0=CCITT V.22, 1=Bell 212A
└───────────── unused
Bits
10 S27 Sync/Async mode
00 asynchronous mode
01 async/sync mode
10 sync auto-dial
11 sync manual dial
Bits
45 S27 Clock Type
00 internal clock used
01 external clock used
10 slaved clock used
[helppc.bosbyte.nl] modem commands