3Com 980/000048/001 manual On-line Operation, Private-line Operation, Dial Backup Operation

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3-6 CHAPTER 3: TROUBLESHOOTING

On-line Operation

Data is scrambled

Check that the character format (data bits, parity, and stop bits) is set to the same value in both modems.

Missing data during a transfer

Check that you are using the same method of flow control for both the modem and the DTE.

If using XON/XOFF flow control, check that the modem’s parity matches the DTE’s parity.

Private-line Operation

Modems do not train-up on private lines

Check that the correct cabling is used for your application.

Check that one modem is configured for answer mode and the other is configured for originate mode.

Check that both modems are using the same modulation scheme.

Dial Backup Operation

Modems do not establish a PSTN link when the Private line fails

Check that the communicating modems are configured to support dial backup, as described in the AccessBuilder 7000 AT Command Reference.

Check that one modem is configured to initiate the backup (i.e. is the master modem, and has the backup telephone number stored in its directory location 8) and the other modem is configured to be a slave (its directory location 8 is empty).

Check that both modems are using the same modulation scheme over their PSTN line.

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Contents Accessbuilder Triple Modem Module User Guide 3Com Corporation 5400 Bayfront Plaza Santa Clara, California Important Safety Information Wichtige Sicherheitshinweise ’INFORMATION DE Sécurité Importante Page Contents Modem Specification and Interface PIN Assignments Index Limited Warranty FCC Class a Verification Statement Page How to Use This Guide This table shows where to find specific informationAbout this Guide IntroductionConventions Icon conventions that are used throughout this guide areText conventions used in this guide are Additional Safety Information Keep the unit away from radiators and heat sourcesAbout this Guide Triple Modem Module Principal Features Support for dial-up transmission protocolsImplementation of V.32terbo Triple Modem Module Typical Applications Modem Connections To The Central SitePack Contents Checklist Registering Ownership of your Triple Modem ModulePre-installation Requirements Triple Modem Module Installation and Operation OverviewInstalling The Module Installing the Rear Card Installing The Rear CardInstalling the Front Card Example of Installing a Front CardConnecting the Cables Front Panel LEDs Front Panel LEDs Installation and Operation Troubleshooting Troubleshooting GuideModem Health Modem does not accept or echo back AT commands Modem DTE ConnectionModem Telephone Line Connection Troubleshooting Perform a local analogue loop test Dial Backup Operation On-line OperationPrivate-line Operation Modem Specification Transmitter / Receiver SpecificationsInterface PIN Assignments Autodial Autoanswer Physical Description ProtocolsApprovals Information General Approvals RequirementsAll the other apparatus shall comprise only Appendix a Modem Specification and Interface PIN Assignments Ringer Equivalence DTE Port Pin Assignments 21/V.1124/V.28 35/V.36 Pstn Port Cable Pin Assignments Private Line Port Cable Pin Assignments On-line Technical Services 3Com Bulletin Board ServiceWorld Wide Web Site Call the telephone number nearest youSupport from Your Network Supplier Support from 3Com Returning Products for Repair Appendix B Technical Support Index NumericsSend LED Limited Warranty 408 764-5000 3/18/96 How to Identify and Resolve Radio-TV Interference Problems