Multi-Tech Systems manual Remote Digital Loopback Test V.54 Loop, Testing the MT3334HD8

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5 Testing the MT3334HD8

3.Note that the CD LED is on. If you’re set for 14,400 bps or higher, the Speed LED should be on. If the CD LED is not on, there is a defect in your modem.

4.Enter characters from your keyboard. For this test, typing multiple uppercase U characters is a good way to send an alternating test pattern of binary ones and zeros. The characters entered should be displayed on your monitor. The TD and RD LEDs should flash when a character is entered.

5.For a more complete test, you should also test the modem in answer mode. To do this, you must first terminate the originate mode by entering an escape sequence (+++AT<CR> or <BREAK>AT<CR>). An OK should appear on your display. Then type ATU1 and press ENTER to place the modem in analog loopback in answer mode.

6.Note that the CD LED is on. If you’re set for 14,400 bps or higher, the Speed LED should be on. If the CD LED is not on, there is a defect in your modem.

7.Enter characters from your keyboard. Type multiple uppercase U characters to send an alternating test pattern of binary ones and zeros. The characters entered should be displayed on your monitor. The TD and RD LEDs should flash when a character is entered.

8.To exit the test, enter an escape sequence (+++AT<CR> or <BREAK>AT<CR>), which returns the modem to command mode.

9.Your modem passes this test if the data received on your monitor are the same as the data entered from your keyboard. If different data appear on your monitor, your modem is probably causing the problem, though it could also be your computer. If your modem passes this test, but you are receiving errors while on line, the remote modem or the phone line could be at fault.

Remote Digital Loopback Test (V.54 Loop 2)

In this test, your modem must be online with another modem, such as another ZDX, that is set up to respond to a request for remote digital loopback. With the ZDX, this ability to respond is controlled by the &T command. AT&T4 enables the response to remote digital loopback; AT&T5 disables the response. The modem defaults to &T5 on power-up, so this must be changed on the remote modem before initiating remote digital loopback.

Initiate remote digital loopback with the ATU2 command, which places the remote modem in digital loopback mode. Data from your computer or terminal are transmitted through your modem and over the phone line to the remote modem, where they are then looped back to your modem. See Figure 3.

Computer or Terminal Local MultiModem

Remote MultiModem Computer or Terminal

UUUUU

 

 

 

 

 

UUUUU

 

 

 

 

 

 

 

Digital Analog

Analog Digital

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Type AT in terminal mode; hit ENTER; dial remote modem; establish online mode; enter escape sequence; type ATU2 and hit ENTER

Figure 3. Remote digital loopback test.

Test procedure

1.Arrange to have &T4 set on the remote test modem.

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 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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