Multi-Tech Systems MT3334HD8 Working with AT Commands, Modes of Operation, Command Structure

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MT3334HD8 User Guide

Working with AT Commands

The MT3334HD8’s modems are controlled by instructions called AT commands, so called because the attention characters AT precede each command or command string (sequence of commands). You can send commands to the modem from your keyboard while in terminal mode, or you can use communi- cations software to issue these commands automatically.

A MT3334HD8 modem is in command mode when it is not dialing or online. When it is in command mode, you have access to a complete communications system that allows you to use several features, including the basic AT command set described in this chapter. Using the basic AT command set, you can enter phone numbers for automatic dialing, configure modem options, and monitor telephone activity. In addition, you can command your modem to perform advanced features such as error correction, data compression, speed conversion, and more.

This chapter describes the MT3334HD8’s operational modes, and shows you how to use each of the MT3334HD8’s AT commands. MT3334HD8 commands and responses are compatible with all systems and with all data communications software using the AT command set.

For easy reference, the MT3334HD8 has a help command that provides you with short, on-screen descriptions of the modem commands. The help command is explained later in this chapter.

Modes of Operation

The MT3334HD8 operates in two basic functional modes: command mode and online mode. (There is also an in-between state, wait-for-carrier, in which the modem is out of command mode but not yet online.) When you power up the modem, it is in command mode, and is ready to accept and respond to commands from your keyboard or software.

An MT3334HD8 modem enters online mode after it dials, connects with another modem, and detects a valid carrier signal. If it does not detect a carrier signal within the time frame controlled by register S7, the modem abandons the call and re-enters command mode.

You can make the modem enter online mode without dialing by typing either the D command or the A command.

The modem exits online mode if the carrier signal is lost or intentionally dropped. When this happens, the modem hangs up and re-enters command mode.

By sending certain “escape” characters to the modem while online, you can make it enter command mode without losing the carrier signal.

For auto answer-only applications, you can disable a modem’s ability to recognize AT commands by using the %DC1 command. When you do this, the MT3334HD8 ignores all commands, and functions as a non- intelligent modem. The %DC1 command and other MT3334HD8 commands are explained later in this chapter.

Command Structure

You can control a wide variety of modem operations and options when the modem is in command mode. AT commands tell the modem to dial a number, to answer a call, to operate at a certain speed, to use a certain compression technique, and many other functions. AT commands consist of one or two letters, which may be preceded by an ampersand (&), a dollar character ($), a pound character (#), a percent character (%), or a greater-than character (>). The Q command, for example, determines whether the modem returns result codes, while the &QcommandselectswhichATcommandsetthemodemuses.

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Contents MT3334HD8 Modem User Guide Multi-Tech Systems, Inc Woodale Drive Mounds View, Minnesota CommPlete Communications Server FCC Fax Warning Canadian Limitations NoticeTable of Contents Appendix D Testing the MT3334HD8Warranty, Service, and Technical Support Appendix FIntroduction Introduction LED IndicatorsPower Supplies Manual OrganizationInstallation Technical Specifications Data Rates ModemIntroduction 2400 & 1200 bps MT3334HD8 User Guide Power Installation Safety Warnings MT3334HD8 modem cardPre-Installation Notes Installation ProcedurePage AT Commands Working with AT Commands Command StructureModes of Operation Command Editing AT Commands by Function $BA Ds Dial Dialing CommandsDial Modifier Commands Continuous RedialPulse or Tone Dialing Wait for New Dial ToneDialing Pause Rn Reverse Originate/Answer ModeReturn to Command Mode After Dialing Flash On-HookCall Card Tone Detect Phone Number Memory Commands@ Quiet Answer DsNd Store a Phone NumberNdNe Number Linking Configuration Storage and Recall CommandsWn Store Configuration List Stored Telephone NumbersModem Response Result Code Commands Fn Load Default ConfigurationReset Modem Echo Command Mode Characters Result Codes Verbose/Terse #An Auto Speed Detection Online Connection CommandsAn Answerback Bn Answer ToneDCn AT Command Control CDn Cleardown at DisconnectDTn Dtmf Detection Hn Busy-Out After Disconnect #Fn Fallback ModesGn Guard Tones Pn Set Pulse-Dial RatiosRDn Square Wave Ring Detect $Tn Calling Tone#Tn Trellis-Coded Modulation Yn Long Space Disconnect CommandsFn Echo Canceler Frequency Offset Compensation RAn Asymmetric Bit RateRS-232 Interface Commands Cn Carrier Detect ControlDn Data Terminal Ready Control RFn CTS/RTS Interaction Control Rn Clear to Send ControlSn Data Set Ready Control SFn DSR/CD Interaction Control#Ln V.42 Error Correction Modes Error Correction and Data Compression CommandsEn Error Correction Modes En Data Compression$En V.42 Error Correction at 300 bps $Fn Auto-Reliable Fallback Character Enable/Disable$An Auto-Reliable Buffering Speed Conversion Commands $BAn Baud Adjust$Rn Retransmit Count $MBn Modem Baud Rate $SBn Serial Port Baud RateInquire Product Code Immediate Action CommandsRepeat Last Command L5, L7 List Current Operating ParametersFlow Control Commands E4 Hardware Flow Control E3 Flow Control DisableEn Non-Error Correction Mode Flow Control E5 XON/XOFF Flow ControlEn Pacing Computer-Initiated Flow Control #Xn Number of Xoff Characters Sent+++ATCR In-Band Escape Sequence Force Answer ModeEscape Sequences Breakatcr Out-of-Band Escape Sequence#Ixxxxxx Change Login Password Remote Configuration CommandsAtcr Remote Configuration Escape Sequence Go Back OnlineDPn Read Line Probe Data Line Probe Commands#Syyyyyy Change Setup Password DFn Format Line Probe DataRP Immediate Line Probe Diagnostic CommandsTn Respond to Remote Digital Loopback Signal Ln Display Line Probe DataUn Loopback Test Modes MT3334HD8 User Guide Registers S1 Ring Count RegistersS0 Number of Rings Until Modem Answers S2 Escape Code CharacterS5 Backspace Character S7 Time for Carrier Abort TimerS4 Line Feed Character S6 Wait Time for Dial ToneS9 Carrier Detect Response Time S10 Carrier Loss Disconnect Delay TimeS13 Remote Configuration Escape Character S11 Tone Dialing Spacing and DurationS24 PBX/CBX Disconnect Drop Time for DSR/CTS/CD S30 Inactivity TimerS34 Command Buffer Length After Online Escape Sequence S25 DTR Dropout TimeS43 Force V.34 Connect Speed S94 Out-of-Service TimeS37 DTR Busy-In Time S48 Maximum V.34 Connect SpeedExamples of Assigning Values AT Commands that Affect S-RegistersReading and Assigning S-Register Values Examples of Reading ValuesAT&E2$SP1#L3$R0$MB19200$SB115200$EB1S0=10&W0CR Testing the MT3334HD8 Test procedure Local Analog Loopback Test V.54 LoopTesting the MT3334HD8 Remote Digital Loopback Test V.54 LoopDial the remote modem and establish your online connection Local Digital Loopback Test V.54 Loop Local digital loopback testPage Warranty, Service, and Technical Support Limited Warranty ServiceTechnical Support Recording Product InformationMulti-Tech BBS Logging onto the Multi-Tech BBSDownloading a File Leaving a Message About CompuServeReading a Message BulletinsAbout the Multi-Tech Fax-Back Service About the InternetUsing FlashPro to Upgrade Firmware Upgrading the MT3334HD8 FirmwareMT3334HD8 User Guide Appendixes Appendix a Ascii Conversion Chart Ctrl Code HEX DECAppendix B Dial Pulses and Tones Dial PulsesTone Dial Frequencies Figure B-2. Standard Dtmf frequencies Appendix C Result Code Summary Multi-Tech Result Codes &Q0Standard AT Result Codes &Q1 Register Unit Range Default Description Appendix D S-Register SummarySets fixed V.34 connect speed = 28800 bps Appendix E AT Command Summary ReturnCDn AT Command Summary $Fn Command Values Description Command Values Description $MBn RAn Command Values Description SFn Command Values Description #Vn Breakatcr Appendix F Remote Configuration Basic ProcedureSetup Changing the Passwords Changing the Remote Escape CharacterIndex MT3334HD8 User Guide Index Long space break Pacing, 36, 37, 38 enable/disable, 38 ENQ/ACK Commands Loopback tests, 42, 43, 54, 56 tone detection
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