Multi-Tech Systems MT4X56USB AT Command Summary, Command Enter Key, Answer, Repeat Last Command

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MultiModemUSB User Guide

Introduction

The AT commands are used to control the operation of your modem. They are called AT commands because each command must be preceded by the characters AT to get the ATtention of the modem.

AT commands can be issued only when the modem is in command mode or online command mode. The modem is in command mode whenever it is not connected to another modem. The modem is in data mode whenever it is connected to another modem and ready to exchange data. Online command mode is a temporary state in which you can issue commands to the modem while connected to another modem. To put the modem into online command mode from data mode, you must issue an escape sequence (+++) followed immediately by the AT characters and the command (e.g., +++ATH to hang up the modem). To return to data mode from online command mode, you must issue the command ATO.

To send AT commands to the modem you must use a communications program, such as the HyperTerminal application in Windows 95/98 and NT 4.0/200041

,or the communications program included with your modem. You can issue commands to the modem either directly, by typing them in the terminal window of the communications program, or indirectly, by configuring the operating system or communications program to send the commands automatically.

Fortunately, communications programs make daily operation of modems effortless by hiding the commands from the user. Most users, therefore, need to use AT commands only when reconfiguring the modem, e.g., to turn autoanswer on or off.

The format for entering an AT command is ATXn, where X is the command and n is the specific value for the command, sometimes called the command parameter. The value n is always a number. If the value is zero, you can omit it from the command; thus, AT&W is equivalent to AT&W0. Most commands have a default value, which is the value that is set at the factory. The default values are shown in the “AT Command Summary,” section below.

You must press ENTER to send the command to the modem. Any time the modem receives a command, it sends a response known as a result code. The most common result codes are OK, ERROR, and the CONNECT messages that the modem sends to the computer when it is connecting to another modem. For a table of valid result codes, see “Result Codes” in this chapter.

You can issue several commands in one line, in what is called a command string. The command string begins with AT and ends when you press ENTER. Spaces to separate the commands are optional; they are ignored by the command interpreter. The most familiar command string is the initialization string, which is used to configure the modem when it is turned on or reset, or when your communications software calls another modem.

AT Command Summary

Command: AT

Attention Code

Values:

n/a

Description:

The attention code precedes all command lines except A/, A:, and escape

 

sequences.

Command: ENTER Key

Values:

n/a

Description:

Press the ENTER (RETURN) key to execute most commands.

Command: A

Answer

Values:

n/a

Description:

Answer incoming call immediately.

Command: A/

Repeat Last Command

Values:

n/a

Description:

Repeat the last command string. Do not precede this command with AT. Do not

 

press ENTER to execute.

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MT4X56USB

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Contents MultiModemUSB Model MT4X56USB User GuideUser Guide Record of RevisionsPatents TrademarksContents Glossary of Terms Index Introduction and Description Introduction FeaturesMultiModemUSB User Guide Technical Specifications InstallationPreview of this Guide Introduction and DescriptionRelated Documentation Front Panel Modem Ports Ports 1, 2, 3,Hub SystemRJ-ll Modem Connector USB Type a Upstream ConnectorUSB Type B Downstream Connector Power ConnectorInstallation Safety Warning Telecom UnpackingInstallation Cabling your MT4X56USBMT4X56USB Software Loading and Configuration Loading your Driver Software System USB SupportMT4X56USB Drivers for Windows 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 NTSelect Add/Remove Programs Uninstalling MultiModemUSB in Windows NTAdd/Remove 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 AT Command Summary Command Enter KeyRepeat Last Command AnswerAT Commands, S-Registers and Result Codes Return Online to Data Mode Result Codes Enable/DisableInformation Request Modulation HandshakeModem Reset Load Factory SettingsTone Dialing Result Code FormatCommunications Mode Asynchronous Communications ModeTest Commands Display Current SettingsStore Current Configuration Select Stored Configuration for Hard ResetCommand &Zy=x Store Dialing Command \An Select Maximum MNP Block Size\Nn Error Correction Mode Selection \Tn Inactivity Timer\Kn Break Control \Qn Flow Control SelectionCommand %DCn AT Command Control Command %En Fallback and Fall Forward ControlEnter Setup Password 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 Setup Remote Configuration ProcedureChanging the Setup Password Remote Configuration and Management Remote Configuration CommandsChanging the Remote Escape Character MT4X56USB Troubleshooting Modem Does Not Respond to Commands None of the Indicators LightModem Dials But Cannot Connect Troubleshooting Modem Disconnects While OnlineModem Cannot Connect When Answering Loopback TestsModem Doesn’t Work with Caller ID 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 testWindows 95/98 Troubleshooting Determining Why USB Support Is Not PresentInstalling Microsoft USB Support Double-click the Universal Serial Bus Controller iconUpgrade Procedure Upgrade Overview Identify the MT4X56USB FirmwareIdentify the Current Firmware Version Multi-Tech Web SiteDownload the Upgrade File Extract the Upgrade FilesUpgrade Procedure Clear Your Stored ParamentersUpgrade the Modem’s Firmware Restore Your ParametersService, Warranty and Tech Support Software User License Agreement Limited Warranty On-line Warranty RegistrationService, Warranty and Tech Support Tech SupportService Contacting Tech Support via E-mailAppendices Appendix a Regulatory Information Class B StatementFCC Part Industry CanadaFCC Part 68 Telecom AppendicesFAX Branding Statement Canadian Limitations NoticeEMC, Safety and Terminal Directive Compliance Commission Decision CTR21New Zealand Telecom Warning Notice International Modem RestrictionsAppendix B V.90 Support TroubleshootingIntroduction Glossary of Terms MT4X56USB Glossary MT4X56USB Glossary MT4X56USB Glossary MT4X56USB Glossary MT4X56USB Glossary MT4X56USB Glossary MT4X56USB Index IndexConfiguration MT4X56USB Software user license agreement Speed