Multi-Tech Systems MT3334SMI Local Digital Loopback Test V.54 Loop, Local digital loopback test

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ModemModule Developer’s Guide

Local Digital Loopback Test (V.54 Loop 2)

The local digital loopback test is identical to the remote digital loopback test with one exception. Instead of using your modem to signal a remote modem to place itself in digital loopback mode, your modem is placed in digital loopback mode while the remote modem is not. Data is entered and transmitted from the remote modem, sent across the phone line to your modem, and looped back to the remote modem.

AT&T3										UUUUUUUUUU
OK										UUUUUUUUUU
OK										UUUUU
	Digital Analog				Analog Digital

Computer or Terminal

Local MultiModem

Remote MultiModem

Computer or Terminal

Figure 6-3. Local digital loopback test

Test Procedure

1.Open your communications software and go into terminal mode. Type AT and press ENTER; you should get an OK message. Type AT\N and press ENTER to disable error correction.

2.Dial the remote modem and establish your online connection.

3.Type the escape sequence +++AT and press ENTER to bring your modem into online command mode.

4.Type AT&T3 and press ENTER. Once you receive an OK message from your modem (if responses are enabled), your modem is placed in digital loopback mode.

5.Have someone enter data from the remote 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 data received by your modem enters its analog receiver, is converted to digital data, is reconverted into analog, and then is transmitted back to the remote modem. Your modem passes this test if the data received on the remote monitor is the same as the data entered from the remote keyboard.

6.To exit the test, type the escape sequence +++AT and press ENTER. This puts the modem in online command mode. The modem should respond with an OK message. If you wish to stay on line with the remote modem for normal data transmission, type AT&T and press ENTER to exit the test, then type ATO and press ENTER to return on line. If you wish to terminate the call, type ATH and press ENTER to hang up.

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MT3334SMI

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Contents Model MT3334SMI Evaluation Kit Data/Fax Socketed ModemRevision Description PatentsContents Index Introduction and Description Product Description FeaturesIntroduction ModemModule Developer’s GuideTechnical Specifications Introduction and Description1200 bps Physical Dimensions MT3334SMI Physical DimensionsDS1 Test/Demo Board SpecificationsLED1-LED4 Test/Demo Board Block Diagram MT3334SMI Test/Demo Board Block DiagramMT3334SMI Pin-out MT3334SMI PinoutTypical Application MT3334SMI Design Considerations Hardware ConsiderationsCalculating Z for Tip and Ring Traces PC Board Layout ConsiderationsRecommended Transceiver Key MT3334SMI PlacementQty Name Description Telecom Labeling Requirements FCC PartIndustry Canada CS-03 ReregistrationMultiple Listing AT Commands, S-Registers, and Result Codes Repeat Last Command AnswerAT Commands, S-Registers, and Result Codes Return Online to Data Mode Monitor Speaker VolumeMonitor Speaker Mode Result Codes Enable/DisableTone Dialing Modem ResetSr? Read Register Value Result Code FormatDisplay Current Settings Command &Fn Load Factory SettingsAsynchronous Communications Mode Store Current Configuration\Bn Transmit Break Command &Zy=x Store Dialing Command\An Select Maximum MNP Block Size \Jn Data Buffer Control\Qn Flow Control Selection \Nn Error Correction Mode Selection\Tn Inactivity Timer \Vn Protocol Result CodeCommand +ES=n Enable Synchronous Buffered Mode Command %DCn AT Command ControlCommand %En Fallback and Fall Forward Control Enter Setup PasswordRegister Unit Range Default Description RegistersS43 Result Codes Terse Verbose DescriptionClass 1 Fax Commands Class 1 Fax Command Summary Command DescriptionFunction Display Current Class Values Default Data modem Class 1 Fax Commands Fax MOD Modulation Parameter ValuesCommand Result Code MeaningFunction Select Service Class Values Default Data mode ModemModule Developer’s Guide CommandFunction Class 1 Fax Commands +FRS=? Enter+FRM=? Enter Result Codes Flow ControlSample Sessions Action by Command Respone Local Modem Remote PC AT+FRH=3 No Carrier ModemModule Developer’s Guide Class 2 Fax Commands +FAA Class 2 Fax Command ImplementationClass 2 Fax Commands EIA SP-2388 August +FAXERR+FCQ +FBOR+FCR +FDCS +FDCCFax Capability Parameters Current Session Results+FDIS +FDFFCData Compression Format Conversion Current Session Parameters+FECM +FDR+FDT +FET+FLNFC +FK+FLID +FLPL+FREL +FPTS+FRBC +FSPL+FHNG +FTSIMT3334SMI Remote Configuration Changing the Setup Password Basic ProcedureSetup ModemModule User GuideRemote Configuration Changing the Remote Escape CharacterMT3334SMI Troubleshooting Test procedure Local Analog Loopback Test V.54 LoopTroubleshooting Remote Digital Loopback Test V.54 LoopLocal Digital Loopback Test V.54 Loop Local digital loopback testUpgrade Procedure Identify the Current Firmware Version Upgrade OverviewIdentify the Modem Firmware Multi-Tech Web SiteUpgrade Procedure Download the Upgrade FileMulti-Tech BBS Restore Your Parameters Extract the Upgrade FilesUse FlashPro to Upgrade Modem Firmware Clear Your Stored ParamentersAppendixes MT3334SMI Canadian Limitations Notice FCC FAX UpdateInternational Modem Restrictions AppendixesEuropean Directives User Guide Statement EMC, Safety and Terminal Directive ComplianceNew Zealand Telecom Warning Notice Programming the Modem Appendix B Multi-Tech Flash Programming ProtocolIntroduction Handshake SequenceOther programming concerns Other supported boot code commandsModemModule Developer’s Guide Program Sequence Data Record Intel Hex FormatXxxx End of File Record Extended Address RecordEeee Index IndexMT3334SM MT3334SMI MT3334SM