Multi-Tech Systems MT4X56USB Remote Digital Loopback Test V.54 Loop, Remote digital loopback test

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MultiModemUSB User Guide

Remote Digital Loopback Test (V.54 Loop 2)

The remote digital loopback test tests the phone lines and the circuits of both your modem and a remote modem. In this test, your modem must be on line with another modem that is set up to respond to a request for remote digital loopback. (Note that some modems might not support remote digital loopback or might have it disabled.) Data from your computer or terminal is transmitted through your modem and over the phone line to the remote modem, where it is then looped back to your modem.

AT&T6

 

 

 

AT&T6

OK

 

 

 

OK

UUUUUUUUU

 

 

 

 

UUUUU

 

 

 

 

 

Digital Analog

Analog Digital

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Computer or Terminal

Local MultiModemUSB

Remote MultiModemUSB

Computer or Terminal

Figure 6-2. Remote digital loopback test.

Test procedure

1.Arrange to have &T6 set on the remote test modem.

2.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.

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

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

5.Type AT&T6 and press ENTER. The local modem responds to this command by transmitting an unscrambled marking signal, which causes the remote modem to place itself in digital loopback mode. Then the local modem exits online command mode and enters data mode.

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

7.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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MT4X56USB

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Contents MultiModemUSB Model MT4X56USB User GuidePatents User GuideRecord of Revisions TrademarksContents Glossary of Terms Index Introduction and Description MultiModemUSB User Guide FeaturesIntroduction Preview of this Guide Technical SpecificationsInstallation Introduction and DescriptionRelated Documentation Hub Front PanelModem Ports Ports 1, 2, 3, SystemUSB Type B Downstream Connector RJ-ll Modem ConnectorUSB Type a Upstream Connector Power ConnectorInstallation Safety Warning Telecom UnpackingInstallation Cabling your MT4X56USBMT4X56USB Software Loading and Configuration MT4X56USB Drivers for Windows System USB SupportLoading your Driver Software Software Loading and Configuration Uninstalling MultiModemUSB in Windows MT4X56USB Drivers for Windows Uninstalling MultiModemUSB in Windows MultiModemUSB Drivers Install dialog box displays Click Next MT4X56USB Drivers for Windows NTAdd/Remove Uninstalling MultiModemUSB in Windows NTSelect Add/Remove Programs MT4X56USB Drivers for Windows Click Finish Software Loading and Configuration Select Add/Remove Hardware Installing Your V.90 Modems Click Start Settings Control Panel ModemsRead Carefully Software Loading and Configuration MT4X56USB Installing Your V.90 Modems Windows Click Start Settings Control Panel Phone and Modems optionMT4X56USB Software Loading and Configuration Windows 95/98 Configuration Utility MT4X56USB Windows NT 4.0/2000 Configuration Utility MT4X56USB MT4X56USB AT Commands, S-Registers and Result Codes Repeat Last Command AT Command SummaryCommand Enter Key AnswerAT Commands, S-Registers and Result Codes Information Request Return Online to Data ModeResult Codes Enable/Disable Modulation HandshakeTone Dialing Modem ResetLoad Factory Settings Result Code FormatTest Commands Communications ModeAsynchronous Communications Mode Display Current SettingsCommand &Zy=x Store Dialing Command Store Current ConfigurationSelect Stored Configuration for Hard Reset \An Select Maximum MNP Block Size\Kn Break Control \Nn Error Correction Mode Selection\Tn Inactivity Timer \Qn Flow Control SelectionEnter Setup Password Command %DCn AT Command ControlCommand %En Fallback and Fall Forward Control Command #S=x Store Setup PasswordCommand +++ATCR Escape Sequence Command %%%ATCRRemote Configuration Escape SequenceRegister Unit Range Default Description RegistersS38 Upstream data ratesResult Codes Terse Verbose DescriptionFor more information on scripting, click the Help button Remote Configuration Changing the Setup Password Remote Configuration ProcedureSetup Changing the Remote Escape Character Remote Configuration CommandsRemote Configuration and Management MT4X56USB Troubleshooting Modem Dials But Cannot Connect None of the Indicators LightModem Does Not Respond to Commands Troubleshooting Modem Disconnects While OnlineModem Doesn’t Work with Caller ID Modem Cannot Connect When AnsweringLoopback Tests Fax and Data Software Can’t Run at the Same TimeTest procedure Local Analog Loopback Test V.54 LoopRemote Digital Loopback Test V.54 Loop Remote digital loopback testLocal Digital Loopback Test V.54 Loop Local digital loopback testInstalling Microsoft USB Support Windows 95/98 TroubleshootingDetermining Why USB Support Is Not Present Double-click the Universal Serial Bus Controller iconUpgrade Procedure Identify the Current Firmware Version Upgrade OverviewIdentify the MT4X56USB Firmware Multi-Tech Web SiteUpgrade Procedure Download the Upgrade FileExtract the Upgrade Files Clear Your Stored ParamentersUpgrade the Modem’s Firmware Restore Your ParametersService, Warranty and Tech Support Software User License Agreement Service, Warranty and Tech Support Limited WarrantyOn-line Warranty Registration Tech SupportService Contacting Tech Support via E-mailAppendices FCC Part Appendix a Regulatory InformationClass B Statement Industry CanadaFCC Part 68 Telecom AppendicesFAX Branding Statement Canadian Limitations NoticeNew Zealand Telecom Warning Notice EMC, Safety and Terminal Directive ComplianceCommission Decision CTR21 International Modem RestrictionsIntroduction TroubleshootingAppendix B V.90 Support Glossary of Terms MT4X56USB Glossary MT4X56USB Glossary MT4X56USB Glossary MT4X56USB Glossary MT4X56USB Glossary MT4X56USB Glossary MT4X56USB Index IndexConfiguration MT4X56USB Software user license agreement Speed