Loopback Tests, Isdn Loopback test AT&T9 | NETGEAR XM128 ISDN

Reference Guide for the Model XM128 ISDN Digital Modem

Note: The LED lights up during the test and blinks if the test fails.

The LNK LED light s up for a half second to indicate the success of the power-on self-test. Then the LNK LED becomes the normal physical layer (layer 1) active indicator.

Loopback Tests

The Model XM128 modem performs several loopback tests as part of its diagnostic capabilities.

ISDN Loopback test (AT&T9)

The AT&T9 command invokes an ISDN loopback test connection. The loopback point is in the S/T interface chip (Siemens 2086 chip) or the U interface chip (Siemens 2091 chip) just behind the line transformers. It checks almost every part of the Model XM128 modem and RS-232 cable except the passive front end of the ISDN S/T or U interface.

During this test, data from the terminal or computer is sent through the DTE interface to the transmitter of the Model XM128 modem. Data is then packetized to the proper frame format according to the B channel protocol selected. Finally, the data is looped back to the receiver, depacketized, and sent through the DTE interface back to the terminal or computer screen. You can tell if anything is wrong by looking at the screen. The screen shows the data you sent to the Model XM128 modem.

Loopback with Self-test (AT&T10)

The AT&T10 command invokes an ISDN loopback connection with self-test. The data is generated by the Model XM128 modem and goes through the same path as the above loopback test does. The data pattern is printable ASCII characters, so you can see the result on the screen. The looped back data is compared with the transmitted data. Should an error occur, the LNK LED starts to flash. Any character sent through the DTE interface to the Model XM128 modem discontinues the test.

10-2	Troubleshooting

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NETGEAR XM128 ISDN manual Loopback Tests, Isdn Loopback test AT&T9, Loopback with Self-test AT&T10

Contents

NETGEAR, Inc USA Trademarks Statement of ConditionsEN 55 022 Declaration of Conformance VCCI-2 Statement Bestätigung des Herstellers/ImporteursCertificate of the Manufacturer/Importer Customer Support Bulletin Board Service World Wide Web Contents Reference Guide for the Model XM128 Isdn Digital Modem Error Correction and Data Compression with Chapter Advanced Isdn Appendix a Technical Specifications Appendix E Connector Pin Assignments Figures Xii Tables Tables Xiii 10-1 Table F-1 Xvi Tables Preface Purpose Conventions Special Message FormatsUse of Enter, Type, and Press Manual contents Related PublicationOther Conventions Manuals DSU Features Chapter Introduction Reference Guide for the Model XM128 Isdn Digital Modem Front Panel Interface OptionsInterface options LED descriptions Label Color Activity DescriptionPWR RTS DTRDSR CTS Rear Panel Rear panel of the Model XM128 modem with S interface Label Description PowerRear panel components ON/OFFPage Chapter Installation Package Contents Installing the Modem Model XM128 modem connections Verifying Hardware Installation Page Setup for Windows 95 and Windows NT Selecting the Appropriate Windows 95 Driver INF file Click on Close Chapter Configuration Configuring Your Isdn Line and NetworkConfiguring Your Modem Using a Terminal Program Operating system Program Understanding AT CommandsTerminal programs Unix Quick Tips for Issuing AT Commands Supported AT command typesType of AT command Example Result codes commands Communication Speed SetupUsing AT Commands to Verify Modem Response Command Description Switch Type Setup for North America Switches supported by the Model XM128 modem Spid Setup for North America Type ATSPIDO=n and Enter Setup for Europe and the United Kingdom Entering DNs Protocol AT command AT commands for setting protocolsAT commands for setting MSN Multiple subscriber number AT command Internet and Remote Access PPP and Slip Chapter Async to Sync PPPMaking Async to Sync PPP and Slip calls Model XM128 modem modem responds Keeping a Line Connection During Idle Time Making a call using Multilink PPP Answering Async to Sync PPP callsMultilink PPP S85 register values Dialing Pre-stored Phone NumbersEndpoint Discriminator Value Description Call Bumping Dynamic Channel Allocation Page Commands for Outgoing Calls Dialing Out Using Isdn ModeChapter Isdn Overview Dialing Out Using Isdn Mode Optional Speech Bearer Service Manually Switching Communication ModesDialing Out for Analog Adapter Port AT Command Dial string it maps to Dialing commandsCall placing commands Placing the Call Commands for Incoming Calls Digital Data Determining the Packet Length Answering a Call Using MSN Commands for assigning Isdn numbers Data over Speech Channel Best-effort Call Answering Command Function Ambiguity Resolution Switch for Voice CallsBest-effort call answering bit commands Multi Auto-Answering of Data Calls Isdn protocol specifications Understanding Isdn Communication ProtocolsParameter 110 120 Isdn Communications Configuration commandsAT Command Description Answering a V.110 Call Selecting V.120 for European Isdn DSS1 Switch Selecting V.120 for German National Isdn 1TR6 Answering a V.120 Call Making a V.120 Call Dialing in V.120 Mode Identifying Your Line Provisioning Kbps Speeds Isdn Communications Europe Answering an X.75 CallMaking an X.75 Call Making a Bundled Call with Dialing Prestored Phone Numbers Bundle Connection with V.42bis Data Compression Page Chapter Advanced Isdn Call Control for DSS1 Control of Outgoing Service Indicator Register values and functionsS108+n= Function Outgoing low-layer compatibility commands Control of Isdn Phone Numbers and SubaddressesS108.n= Function Reference Guide for the Model XM128 Isdn Digital Modem Call Control for 1TR6 Old German Isdn Command Function Control of EAZ Endgeräteauswahlziffer Answering a Call Answering a Call for DSS1 Answering a Call for 1TR6 Best-effort Call Answering Ambiguity Resolution Switch for Voice Calls Multi-Auto-Answering of Data Calls Disable Inbound Call Connection Data Call Indication Point-to-Point Configuration Placing a CallPlacing a Call for DSS1 Placing a Call for 1TR6 User-To-User Information Page Chapter Analog Call Handling Frequently used AT commands European switches AT Commands for Analog CallsFrequently used AT commands AT Command Description of command Making and Receiving Analog Calls Placing a Call from the Analog Adapter Accepting an Incoming Call Definitions for the d modifier Chapter Modem UpgradeUpgrading with Flash Eprom Modifier Definition Upgrade Instructions Kernel Mode Test Sequence Chapter TroubleshootingPower-on Self-test Test Description Loopback Tests Isdn Loopback test AT&T9Loopback with Self-test AT&T10 Diagnostic Command B1/B2 Loopback with Self-test Modem Reset Using The Embedded Protocol Analyzer Setting up the Embedded EPA Capturing the Protocol Data Analyzing the Captured Data EPA CommandsCommands for analyzing captured data Atct Control key functions Key Function DescriptionPage Network Protocols and Standards Compatibility Appendix a Technical SpecificationsGeneral Specifications Security Environmental Specifications Power AdapterPhysical Specifications Data Compression Appendix B Security Functions Security Types and Levels Table B-1 Types of security Level 1 SecurityLevel 2 Security Type 1 Security Type 2 Security Table B-2 Levels of security Setting and Modifying PasswordsLevel 3 Security Level AT*GC0 Nonpassword Auto Callback FunctionTable B-3 Auto callback commands AT*GC1 Appendix C AT Command Set Reference Operation Mode of the DTE InterfaceSimplex Mode AT Command Descriptions Table C-1 Basic AT command setCommand Options Function and description CH? CE0CE1 CL? CP0 CP1Dtmf USA Model XM128 modem returns result code SPID1 Description of ATI3 OutputSPID0 SPID? Table C-2 ATI3 command output Table C-3 Extended AT& command setOutput parameter Output value description Result Codes Knn =phone number Table C-4 lists the extended AT* command set Table C-4 Extended AT* command set Viewing and Setting S-Registers Appendix D Status Registers and Result Codes Setting S-Registers Examples for Setting S-Registers Bit Binary Decimal Hexadecimal Value Table D-2 Setting bitTable D-1 Binary conversion table Operation Example Decimal Hexadecimal Binary Command Function and description Default Register DescriptionsTable D-3 Basic S-registers ATSn=x Table D-4 Extended S-registers ATSn=x See also S-register ATX1 ATX2 ATX3 ATX4 S24= Bitmapped register S35= Bitmapped register When Data/Voice is pressed Do not send low-layer compatibility Enables loopback 4 test DCA function is enabled Reference Guide for the Model XM128 Isdn Digital Modem Reference Guide for the Model XM128 Isdn Digital Modem Reference Guide for the Model XM128 Isdn Digital Modem Message handling systems MHS Reference Guide for the Model XM128 Isdn Digital Modem Speed is greater than 19200 bps Table D-5 ATXn command setting options ATXn Result Code Option Table Connect Result Code Chart Symbol Reference Table D-6. Result code chartSupported Result Code Field Descriptions Table D-7 Result code field descriptionsField name Possible values Connect Strings for Error Corrected Connections Table D-8 Connect stringsPage Appendix E Connector Pin Assignments RJ-45 Plug and Connector Pin Assignment RCV + XMT + RJ-11 Plug and Connector Table E-3. RJ-11 connector pin assignmentsPage RS-232 Serial Interface Signal/pin description Signal direction Signal nameAppendix F Serial Port Interface Table F-1 Serial port interface TXD RXD RTS CTS DSR Asynchronous Cable ConnectionsTable F-2 Asynchronous flow control cable connection CD DCD DTR Appendix G Isdn Reference Isdn Overview Out-of-Band Signaling Basic Rate Interface Terminal Adapter or Digital Modem Isdn Basic Rate Interface Points Ordering Isdn Service Spid Setup Reference Guide for the Model XM128 Isdn Digital Modem Order Form for AT&T 5ESS Switch NI-1 Isdn Table G-1 Isdn line configuration Order Form for DMS-100 Switch NI-1 or Custom Isdn Table G-2 Isdn line configuration Table G-3 Isdn line configuration Order Form for Ewsd NI-1 Isdn Index Numerics Isdn Reference Guide for the Model XM128 Isdn Digital Modem Reference Guide for the Model XM128 Isdn Digital Modem