Multi-Tech Systems MT3334HD8 Speed Conversion Commands, $Rn Retransmit Count, $BAn Baud Adjust

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3 AT Commands

$Rn Retransmit Count

n = 0 or 1 Default: $R0

If errors are received during a reliable connection, the modem re-sends the block of data that contained an error. If another error occurs, it re-sends the block again. The modem counts the number of times that a data block is re-sent.

$R0 causes the modem to disconnect if the same block of data is re-sent 12 times without being received properly, on the assumption that the line is unsuitable for transmission.

$R1 causes the modem to disable the retransmit counter, so that the modem keeps trying to send data and will not abort, no matter how many times the same block is resent. Type AT$R0 to disconnect the modem if all attempts to re-send the block fail.

Speed Conversion Commands

Speed conversion allows the MT3334HD8 to communicate at a fixed speed through the serial port while communicating at an independent speed over the online communications link.

Speed conversion is necessary for data compression, since data compression requires data to be sent from the computer to the modem at a rate up to four times faster than the modem’s transmission speed.

Speed conversion is also useful for an auto answer modem connected to a computer that does not have auto baud capability, since the computer must be set at a fixed baud rate regardless of the speed at which the modem communicates over the phone line.

$BAn Baud Adjust

n = 0 or 1 Default: $BA0

Even though the term “baud adjust” sounds like it should mean the same thing as “speed conversion,” it actually means the opposite. Turning baud adjust off turns speed conversion on; turning baud adjust on turns speed conversion off.

When baud adjust is on, the modem matches its RS-232 serial port speed to any changes in the computer’s serial port speed in originate mode, or to the speed of the originating modem when it’s in answer mode. With baud adjust on, the speed at which the modem communicates over the phone line is always the same as the speed at which it communicates via its RS-232 serial port.

When speed conversion is on, the modem does not adjust its speed at the serial port to match its transmission speed. Serial port speed and transmission speed can therefore be set independently. Speed conversion is necessary for a high speed modem that is connected to a limited speed serial port.

$BA0 turns baud adjust off and speed conversion on.

$BA1 turns baud adjust on and speed conversion off.

CommPlete Communications Server

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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 Appendix F Testing the MT3334HD8Warranty, Service, and Technical Support Appendix DIntroduction Manual Organization LED IndicatorsPower Supplies IntroductionInstallation Data Rates Modem Technical SpecificationsIntroduction 2400 & 1200 bps MT3334HD8 User Guide Power Installation MT3334HD8 modem card Safety WarningsInstallation Procedure Pre-Installation NotesPage AT Commands Working with AT Commands Command StructureModes of Operation Command Editing AT Commands by Function $BA Continuous Redial Dialing CommandsDial Modifier Commands Ds DialWait for New Dial Tone Pulse or Tone DialingFlash On-Hook Rn Reverse Originate/Answer ModeReturn to Command Mode After Dialing Dialing PauseDsNd Store a Phone Number Phone Number Memory Commands@ Quiet Answer Call Card Tone DetectList Stored Telephone Numbers Configuration Storage and Recall CommandsWn Store Configuration NdNe Number LinkingModem Response Result Code Commands Fn Load Default ConfigurationReset Modem Echo Command Mode Characters Result Codes Verbose/Terse Bn Answer Tone Online Connection CommandsAn Answerback #An Auto Speed DetectionDCn AT Command Control CDn Cleardown at DisconnectDTn Dtmf Detection Pn Set Pulse-Dial Ratios #Fn Fallback ModesGn Guard Tones Hn Busy-Out After DisconnectRDn Square Wave Ring Detect $Tn Calling Tone#Tn Trellis-Coded Modulation RAn Asymmetric Bit Rate CommandsFn Echo Canceler Frequency Offset Compensation Yn Long Space DisconnectRS-232 Interface Commands Cn Carrier Detect ControlDn Data Terminal Ready Control SFn DSR/CD Interaction Control Rn Clear to Send ControlSn Data Set Ready Control RFn CTS/RTS Interaction ControlEn Data Compression Error Correction and Data Compression CommandsEn Error Correction Modes #Ln V.42 Error Correction Modes$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 $SBn Serial Port Baud Rate $MBn Modem Baud RateL5, L7 List Current Operating Parameters Immediate Action CommandsRepeat Last Command Inquire Product CodeFlow Control Commands E5 XON/XOFF Flow Control E3 Flow Control DisableEn Non-Error Correction Mode Flow Control E4 Hardware Flow Control#Xn Number of Xoff Characters Sent En Pacing Computer-Initiated Flow ControlBreakatcr Out-of-Band Escape Sequence Force Answer ModeEscape Sequences +++ATCR In-Band Escape SequenceGo Back Online Remote Configuration CommandsAtcr Remote Configuration Escape Sequence #Ixxxxxx Change Login PasswordDFn Format Line Probe Data Line Probe Commands#Syyyyyy Change Setup Password DPn Read Line Probe DataLn Display Line Probe Data Diagnostic CommandsTn Respond to Remote Digital Loopback Signal RP Immediate Line ProbeUn Loopback Test Modes MT3334HD8 User Guide Registers S2 Escape Code Character RegistersS0 Number of Rings Until Modem Answers S1 Ring CountS6 Wait Time for Dial Tone S7 Time for Carrier Abort TimerS4 Line Feed Character S5 Backspace CharacterS11 Tone Dialing Spacing and Duration S10 Carrier Loss Disconnect Delay TimeS13 Remote Configuration Escape Character S9 Carrier Detect Response TimeS25 DTR Dropout Time S30 Inactivity TimerS34 Command Buffer Length After Online Escape Sequence S24 PBX/CBX Disconnect Drop Time for DSR/CTS/CDS48 Maximum V.34 Connect Speed S94 Out-of-Service TimeS37 DTR Busy-In Time S43 Force V.34 Connect SpeedExamples of Reading Values AT Commands that Affect S-RegistersReading and Assigning S-Register Values Examples of Assigning ValuesAT&E2$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 SupportMulti-Tech BBS Logging onto the Multi-Tech BBSDownloading a File Bulletins About CompuServeReading a Message Leaving a MessageAbout 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 ChartAppendix B Dial Pulses and Tones Dial PulsesTone 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 Appendix F Remote Configuration Basic ProcedureSetup 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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