Multi-Tech Systems MT3334HD8 Error Correction and Data Compression Commands, En Data Compression

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3 AT Commands

Error Correction and Data Compression Commands

You can configure a modem to any of three different V.42 modes of operation (each mode can be with or without compression). They are the non-error correction, auto-reliable, and reliable modes. You can also turn data compression on or off.

&En Error Correction Modes

n = 0, 1, or 2 Default: &E1

Select the modem’s error correction mode using the &E0, &E1, or &E2 command.

&E0 disables the modem’s V.42 error correction capabilities, and the modem functions as a non-error correction modem.

&E1 enables auto-reliable mode. During the handshaking procedures at the start of the online connection, the modem queries whether the other modem is using V.42 error correction. If the modem determines that the other modem is using V.42, it switches itself into reliable (V.42) mode and enables error correction. If it determines that the other modem is not using V.42, the modem remains in non-error correction mode.

&E2 enables reliable mode, in which the modem uses its V.42 error correction capabilities for all transmissions. In reliable mode, the modem must be connected to a modem with a V.42 protocol (MNP or LAP-M).

The V.42 standard includes MNP Class 3 and 4 and LAP-M error correction methods. The V.42 mode select command (#L) selects which type of error correction the modem uses for transmissions.

&En Data Compression

n = 14 or 15 Default: &E15

Data compression is normally enabled, providing &E1 (auto-reliable mode) or &E2 (reliable mode) has also been selected. However, you may wish to turn it off in certain circumstances.

&E14 disables data compression.

&E15 enables data compression.

#Ln V.42 Error Correction Modes

n = 0–3 Default: #L0

The #L command selects the V.42 error correction method (MNP or LAP-M) the modem uses when originating a call. In answer mode, the modem ignores the #L command and accepts whichever V.42 mode, MNP or LAP-M, the originating modem offers.

#L0 causes the modem to negotiate the V.42 error correction method with the answering modem, and to begin negotiation with LAP-M. If both modems have LAP-M capability, the modems will use LAP-M mode. If one or both modems do not have LAP-M capability and both have MNP, the modems will use MNP.

#L1 enables MNP error correction and disables LAP-M.

#L2 enables LAP-M error correction and disables MNP.

#L3 enables LAP-M error correction and disables MNP, but skips the V.42 detection phase used by the other commands. Both modems must be set with #L3.

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Contents MT3334HD8 Modem User Guide Multi-Tech Systems, Inc Woodale Drive Mounds View, Minnesota CommPlete Communications Server Canadian Limitations Notice FCC Fax WarningTable of Contents Warranty, Service, and Technical Support Testing the MT3334HD8Appendix D Appendix FIntroduction Power Supplies LED IndicatorsIntroduction Manual OrganizationInstallation Data Rates Modem Technical SpecificationsIntroduction 2400 & 1200 bps MT3334HD8 User Guide Power Installation MT3334HD8 modem card Safety WarningsInstallation Procedure Pre-Installation NotesPage AT Commands Command Structure Working with AT CommandsModes of Operation Command Editing AT Commands by Function $BA Dial Modifier Commands Dialing CommandsDs Dial Continuous RedialWait for New Dial Tone Pulse or Tone DialingReturn to Command Mode After Dialing Rn Reverse Originate/Answer ModeDialing Pause Flash On-Hook@ Quiet Answer Phone Number Memory CommandsCall Card Tone Detect DsNd Store a Phone NumberWn Store Configuration Configuration Storage and Recall CommandsNdNe Number Linking List Stored Telephone NumbersFn Load Default Configuration Modem Response Result Code CommandsReset Modem Echo Command Mode Characters Result Codes Verbose/Terse An Answerback Online Connection Commands#An Auto Speed Detection Bn Answer ToneCDn Cleardown at Disconnect DCn AT Command ControlDTn Dtmf Detection Gn Guard Tones #Fn Fallback ModesHn Busy-Out After Disconnect Pn Set Pulse-Dial Ratios$Tn Calling Tone RDn Square Wave Ring Detect#Tn Trellis-Coded Modulation Fn Echo Canceler Frequency Offset Compensation CommandsYn Long Space Disconnect RAn Asymmetric Bit RateCn Carrier Detect Control RS-232 Interface CommandsDn Data Terminal Ready Control Sn Data Set Ready Control Rn Clear to Send ControlRFn CTS/RTS Interaction Control SFn DSR/CD Interaction ControlEn Error Correction Modes Error Correction and Data Compression Commands#Ln V.42 Error Correction Modes En Data Compression$Fn Auto-Reliable Fallback Character Enable/Disable $En V.42 Error Correction at 300 bps$An Auto-Reliable Buffering $BAn Baud Adjust Speed Conversion Commands$Rn Retransmit Count $SBn Serial Port Baud Rate $MBn Modem Baud RateRepeat Last Command Immediate Action CommandsInquire Product Code L5, L7 List Current Operating ParametersFlow Control Commands En Non-Error Correction Mode Flow Control E3 Flow Control DisableE4 Hardware Flow Control E5 XON/XOFF Flow Control#Xn Number of Xoff Characters Sent En Pacing Computer-Initiated Flow ControlEscape Sequences Force Answer Mode+++ATCR In-Band Escape Sequence Breakatcr Out-of-Band Escape SequenceAtcr Remote Configuration Escape Sequence Remote Configuration Commands#Ixxxxxx Change Login Password Go Back Online#Syyyyyy Change Setup Password Line Probe CommandsDPn Read Line Probe Data DFn Format Line Probe DataTn Respond to Remote Digital Loopback Signal Diagnostic CommandsRP Immediate Line Probe Ln Display Line Probe DataUn Loopback Test Modes MT3334HD8 User Guide Registers S0 Number of Rings Until Modem Answers RegistersS1 Ring Count S2 Escape Code CharacterS4 Line Feed Character S7 Time for Carrier Abort TimerS5 Backspace Character S6 Wait Time for Dial ToneS13 Remote Configuration Escape Character S10 Carrier Loss Disconnect Delay TimeS9 Carrier Detect Response Time S11 Tone Dialing Spacing and DurationS34 Command Buffer Length After Online Escape Sequence S30 Inactivity TimerS24 PBX/CBX Disconnect Drop Time for DSR/CTS/CD S25 DTR Dropout TimeS37 DTR Busy-In Time S94 Out-of-Service TimeS43 Force V.34 Connect Speed S48 Maximum V.34 Connect SpeedReading and Assigning S-Register Values AT Commands that Affect S-RegistersExamples of Assigning Values Examples of Reading ValuesAT&E2$SP1#L3$R0$MB19200$SB115200$EB1S0=10&W0CR Testing the MT3334HD8 Local Analog Loopback Test V.54 Loop Test procedureRemote Digital Loopback Test V.54 Loop Testing the MT3334HD8Dial the remote modem and establish your online connection Local digital loopback test Local Digital Loopback Test V.54 LoopPage Warranty, Service, and Technical Support Service Limited WarrantyRecording Product Information Technical SupportLogging onto the Multi-Tech BBS Multi-Tech BBSDownloading a File Reading a Message About CompuServeLeaving a Message BulletinsAbout the Internet About the Multi-Tech Fax-Back ServiceUpgrading the MT3334HD8 Firmware Using FlashPro to Upgrade FirmwareMT3334HD8 User Guide Appendixes Ctrl Code HEX DEC Appendix a Ascii Conversion ChartDial Pulses Appendix B Dial Pulses and TonesTone Dial Frequencies Figure B-2. Standard Dtmf frequencies Multi-Tech Result Codes &Q0 Appendix C Result Code SummaryStandard AT Result Codes &Q1 Appendix D S-Register Summary Register Unit Range Default DescriptionSets fixed V.34 connect speed = 28800 bps Return Appendix E AT Command SummaryCDn AT Command Summary $Fn Command Values Description Command Values Description $MBn RAn Command Values Description SFn Command Values Description #Vn Breakatcr Basic Procedure Appendix F Remote ConfigurationSetup Changing the Remote Escape Character Changing the PasswordsIndex 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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