U.S. Robotics 56K Business Modem Commands
This card provides a quick reference for the most commonly used AT commands. Defaults in bold type. NOTE: Refer to the Alphabetic Command Summary, in the Command Reference on the Installation CD-ROM for additional commands, like the Percent (%) and Octothorpe (#) command sets.

BASIC COMMAND SET

Command/Description
$ +++ > A A/ A> AT Bn Displays Help for the basic command set Escape code Repeat command (up to 10 attempts) modem answers when theres no incoming call Reexecutes the last-issued command Repeats the last issued command until canceled Attention prefix Sets handshaking options: B0 ITU-T V.32 originate mode B1 HST originate mode; Bell answer tone Sets transmitter C0 Transmitter off C1 Transmitter on Dials phone numbers and issues commands for dialing options: P Pulse dial T Tone dial , (Comma) Pause for 2 seconds ; (Semicolon) Return to command mode after dialing Dial the letters that follow W Wait for a second dial tone (if X3 or higher) @ Wait for an answer (with X3, X4 or X7) / Pause for 125 milliseconds R Reverse frequencies ! Flash the switchhook L? Display the last-dialed number L Redial the last number Sn Dial number stored in non-volatile random access memory (NVRAM) at position n $ Display Help for the dial commands Command mode echo E0 Echo OFF; What you type will not display E1 Echo On; What you type will display Online local echo F0 Echo ON F1 Echo OFF On/Off hook control H0 Go on hook (hang up) H1 Go off hook (pick up) Queries the modem I3 Banner I4 Current settings

Sr=n Sr.b=n Sr? S$ T Vn

Xn X3 X4 X7 Z Z!
I5 NVRAM settings I6 Statistics for preceding call I7 Product configuration I10 Dial security account status I11 Extended Link Screen I15 Caller ID information Controls the modem clock K0 If online, current call duration K1 Displays real time Controls speaker volume L0 Low volume L1 Low volume L2 Medium volume L3 High volume Controls when the speaker sounds M0 Always OFF M1 ON until call is negotiated M2 Always ON M3 ON after last digit is dialed Return online; use with escape code (+++) O0 Return online O1 Return online and retrain Pulse dial Enables or disables the display of result codes Q0 Display Q1 Suppress (quiet) Q2 Suppress when answering Sets S-register value; r is any S-Register; n must be a decimal between 0 and 255 Sets bit-mapped register; r is the S-register, b is the bit, and n is 0 (OFF) or 1 (ON) Queries contents of S-register r Displays s-register help Tone dial Displays result codes verbally or numerically V0 Numeric V1 Verbal Call progress reporting Ignore dial tone Microsoft default Courier V.Everything Modem default Software reset Hardware reset

&Bn

&Cn

&Dn

&Fn

&Gn

&Hn

&In

&Kn
AMPERSAND (&) COMMAND SET

&Mn

&$ &An Displays Help for the ampersand (&) command set Enables or disables the additional result code subsets &A0 Disables the display of additional result codes &A1 Displays ARQ result codes &A2 Displays ARQ result codes, modulation indicators
Displays ARQ result codes, modulation indicators, and error control indicator Sets the serial port rate &B0 Variable Fixed &B1 &B2 Fixed serial port rate in ARQ mode; variable rate in non-ARQ mode Controls Carrier Detect (CD) &C0 CD always on Normal CD operations &C1 Controls Data Terminal Ready (DTR) &D0 Ignore DTR &D1 Online command mode with DTR toggle &D2 Normal DTR operations &D3 Modem resets with DTR toggle Loads configuration template &F0 Loads No flow control template &F1 Loads Hardware flow control template &F2 Loads Software flow control template Sets guard tone &G0 No guard tone (U.S., Canada) &G1 Guard tone (Some European countries) &G2 Guard tone (UK); requires ATB0 Transmit Data flow control &H0 Disables Transmit Data flow control &H1 Hardware Clear to Send (CTS) flow control &H2 Software flow control (XON/XOFF) &H3 Hardware and software flow control Received Data software flow control &I0 Disables XON/XOFF flow control &I1 Modem acts on XON/XOFF commands and passes them to the remote device &I2 Modem acts on XON/XOFF commands and removes commands from the data stream (recommended for ARQ mode) &I3 External: Hewlett Packard-Host mode (ARQMode Only) &I4 External:Hewlett Packard-Terminal mode (ARQMode Only) &I5 XON/XOFF in non ARQ Mode Enables or disables data compression &K0 Disable &K1 Auto enable/disable &K2 Enable &K3 Selective compression (V.42 bis only) Error control &M0 Normal mode; no error control &M4 Normal /ARQ mode &M5 Asynchronous ARQ mode &A3

&Nn Sets fixed link speed &Nn&Un Sets highest and lowest link speeds Variable connection rate n=0 n=bps n = 21 33.3 Kbps 1200 bps n = 22 34.6 Kbps n=2 n=bps n = 23 36.0 Kbps 4800 bps n = 24 37.3 Kbps n=4 n=bps n = 25 38.6 Kbps n=bps n = 26 40.0 Kbps 12.0 Kbps n = 27 41.3 Kbps n=7 n=8 14.4 Kbps n = 28 42.6 Kbps n=9 16.8 Kbps n = 29 44.0 Kbps 19.2 Kbps n = 30 45.3 Kbps n = 10 n = 11 21.6 Kbps n = 31 46.6 Kbps n = 12 24.0 Kbps n = 32 48.0 Kbps n = 13 26.4 Kbps n = 33 49.3 Kbps 28.8 Kbps n = 34 50.6 Kbps n = 14 n = 15 31.2 Kbps n = 35 52.0 Kbps 33.6 Kbps n = 36 53.3 Kbps n = 16 n = 17 28.0 Kbps n = 37 54.6 Kbps n = 18 29.3 Kbps n = 38 56.0 Kbps n = 19 30.6 Kbps n = 20 32.0 Kbps &Rn Received Data (RTS) hardware flow control &R0 Delay clear to send (CTS) response after RTS &R1 Ignore RTS &R2 Send data to the computer on receipt of RTS &Sn Data Set Ready (DSR) signal from modem to pc &S0 DSR always on &S1 Originate mode: Send DSR after dialing Answer mode: Send DSR after tone &S2 Pulsed DSR with CTS following CD &S3 Same as &S2, but without CTS &S4 Simultaneous DSR with CD &S5 Send DSR, and follow CTS with CD &W Writes the current settings to NVRAM &Zn=s Stores up to 10 phone numbers in NVRAM at position n where n = 0-9 &Zn? Displays the stored phone number

S-REGISTERS

Register Default Function
S0 S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 S11 S12 S6 Sets the number of rings before Auto Answer Counts and stores number of rings from calls Stores code for the escape code character Stores the code for the carriage return Stores the code for the line feed character Stores the code for the back space character Stores the wait time for dial tone Stores the wait time for carrier Sets the comma time in seconds Sets duration (1/10 of sec.) of remote carrier signal before modem recognition 14 Sets duration (1/10 of sec.) modem waits after loss of carrier before hanging up 70 Set touch tones spacing in 1/10 seconds. 50 Sets the guard time for the escape code 0 Bit-mapped register Bit Value Result Reset when DTR drops Originate mode in Auto Answer Disables pause before result codes Auto Dial the number stored in NVRAM position 0 on DTR At power on, Auto Dial number stored in NVRAM at position 32 Disable HST Disable MNP Level 128 Hardware Reset 0 Bit-mapped register Bit Value Result Disconnects on Escape code 0 Bit-mapped register Bit Value Result Disables high frequency equalisation Disables online fallback Disables 450 bps back channel Sets non-ARQ buffer to 128 bytes Disables MNP Level 32 Set backspace key to delete Unusual MNP incompatibility Custom applications only 0 Sets the inactivity timeout, in minutes 10 Length of break in ARQ mode, 1/100 seconds 17 Stores the ASCII code for the XON character 19 Stores the ASCII code for the XOFF character 150 Sets DSR pulse time in 20-milliseconds

S25 S26 S27

S28 S29 S34

S38 S41 S42 S43 S44 S51

S19 S21 S22 S23 S24
Sets DTR recognition in 10-milliseconds Sets the RTS/CTS delay, 10-milliseconds Bit-mapped register Value Result 1 Enables V.21 modulation at 300 bps 2 Disables Trellis Code modulation 4 Disables V.32 modulation 8 Disables 2100 Hz answer tone 16 See Bit 4 and Bit 5 below 32 See Bit 4 and Bit 5 below 128 Unusual software compatibility Bit5 Result 0 Complete handshaking sequence 0 Disables MNP 32 Disables V.42 detection and LAPM 32 Disables detection phase Sets duration, in tenths of a second, of extra 3000/600 Hz answer tones 20 Sets, in tenths of a sec, of the V.21answer tone 0 Bit-mapped register Bit Value Result Disables V.32 bis Disables enhanced V.32 Mode Disables Quick V.32 Retrain Enables V.23 modulations Externals: Forces MR LED to show DSR Disables remote access busy message Disables V.32 terbo 0 Sets duration, in seconds, before a forced hang up 0 Sets number of attempts for remote access 126 Stores the ASCII code for remote access escape 200 Sets the guard time for the remote access sequence, in 1/50th of a second 15 Leased line delay timer 0 Bit-mapped register Bit Value Result Disables MNP/V.42 in V.2 Disables MNP/V.42 in V.22bis Disables MNP/V.42 in V.64 Disables selective reject 0 Bit-mapped register Bit Value Result Enables dial security Enables prompting Enables local password protection 64 Symbol bit-mapped register Bit Value Result Disable 2400 symbol rate Disable 2743 symbol rate

0 Bit 7 Bit16 8

0 Bit Bit 0 Bit 0 Bit 0 Bit 2 3
4 Disable 2800 symbol rate 8 Disable 3000 symbol rate 16 Disable 3200 symbol rate 32 Disable 3429 symbol rate 64 Disable Call Indicate (CI) 128 Disable V.8 Trellis code bit-mapped register Value Result 1 Disable 8S-2D trellis code 2 Disable 16S-4D trellis code 4 Disable 32S-2D trellis code 8 Disable 64S-4D trellis code 128 Enable phase roll detection Bit-mapped register Value Result 1 Disable non-linear coding 2 Disable TX level deviation 4 Disable preemphasis 8 Disable precoding 16 Disable shaping 32 Disable V.34+ 64 Disable V.Disable V.FC Bit-mapped register Value Result 32 Disables V.Disables V.92 Bit-mapped register Value Result 1 Disables plug/play signalling 2 Enables carrier loss redial Bit-mapped register Value Result 1 Enables recognition of Ring A 2 Enables recognition of Ring B 4 Enables recognition of Ring C 8 Enables recognition of Ring D

U.S. Robotics 56K Business Modem

Quick Reference Card

PN R24.0368.00 Copyright 2003 U.S. Robotics Corporation. All rights reserved. U.S. Robotics and the U.S. Robotics logo are registered trademarks of U.S. Robotics Corporation. Other product names are for identification purposes only and may be trademarks of their respective companies. Product specifications subject to change without notice.

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