Have no error control Normal Mode, AT&M0, AT&M4, AT&M5 | 3Com 56K

12-6CHAPTER 12: HANDSHAKING, ERROR CONTROL, DATA COMPRESSION, AND THROUGHPUT

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For your modem to	Command

Have no error control (Normal Mode)	AT&M0
Due to the nature of phone line channels, this is never
recommended for analog calls above 2400 bps

Operate in Normal mode if an ARQ connection can’t be	AT&M4
made (Normal/ARQ mode)

Hangs up if it can’t make an ARQ connection (ARQ	AT&M5
Asynchronous Mode)

Example: Sending AT&M4 allows your modem to operate in Normal Mode is an ARQ connection can’t be made.

Error control is available for calls at 1200 bps and above. It can be disabled, although high-speed calls (9600 bps or higher) should always be under error control. The operations defined in an error-control protocol include:

■Establishing compatibility.

■Formatting data frames.

■Detecting errors using Cyclic Redundancy Checking (CRC).

■Retransmitting corrupt data frames.

The Business Modem is set at the factory to try for an error-control connection and, if that isn't possible, to proceed with the call in Normal mode. This means that &M4 is set.

Image 102

3Com 56K manual Have no error control Normal Mode, AT&M0, AT&M4, AT&M5, Asynchronous Mode

Contents

3Com OfficeConnect 56K Business Modem Command Reference 3Com Corporation 3800 Golf Rd Rolling Meadows, Illinois United States Government Legend Contents Other Operating Systems If You Are Using MS-DOSCommand and Online Modes Making International calls Data Terminal Ready Data Set Ready Carrier Detect Result Code Display Commands Additional Result Code SubsetsOverview Overview Serial Port Rates Connection Rates Password Prompting Setting DTE Rate to 230 KbpsSetting up Dial Security Remote Configuration Testing the Business Modem using AT&Tn Error ControlMNP Error Control Received Data Flow Control Canceling All Digital Loopback Test Requests &T5 Digital Loopback Testing AT&T3Remote Digital Loopback Testing AT&T6, AT&T7 Testing Using Keyboard Data AT&T6 If Your Modem Doesn’t Respond Getting New Operating SoftwareSending New Software to your modem Hardware Flow Control Software Flow control No Flow Control Additional Specifications Serial Ports Serial Ports Macintosh modemRegisters Finding Specific About this GuideIntroduction Information This Guide Convention Description ConventionsIcon Description Wait n seconds between losing the connection Related About this Guide Connecting to Your ISP Windows 95/98 Your modem is now ready to use This file Does thisModem software If Dial-Up Adapter Do this Is listed NetworkingIs not listed Go to Step Click Finish If TCP/IP Dial-Up Adapter Do thisClick Add Protocol Microsoft TCP/IP OK Windows 95/98 Click OK, and OK Step Four Customizing the TCP/IP SettingsClick TCP/IP Settings If your ISP Do this Click Specify name server addresses and enter Specify an IP address, if neededClick Server assigned IP address Click Server assigned server address For you to Use this connection Select Remote Access Service and click Properties Go to Start Settings Control Panel ModemsSetting up RAS Check Don’t detect my modem I will select it from a list Go to Start Programs Accessories Dial Up Networking Click Continue to complete RAS setupSelect Start Settings Control Panel Click Network Select Enable software compression Specify an IP address by clicking TCP/IP settingsDouble-clickDial-Up Networking Macintosh Make sure Use Telephony Dialing Properties is uncheckedMacintosh computers Installing the script System Configuration Accessing InternetInstallation Script and then configure Open Transport PPP Slip or PPP dialing software Transport PPP Go to Apple Menu Control Panels Modem Macintosh Go to Apple Menu Control Panels PPP Systems If You Are UsingOther Operating Windows 18CHAPTER 1 Connecting to Your ISP Overview Using the AT Command SETUsing AT commands General rules for Re-execute the last-issued command Dial the following number using tone dialingTo configure your modem to Command Use the X2 result code subset To change Command Settings for a register in the current configurationTo display Command ATI5 Registers UnderstandingBit-mapped Getting a list Registers Modes of Operation Command and Online ModesIf you want to Set the modem to Use this command ATO0 Return online and retrain If you want to Command Return onlineMode ATO1 Online Mode Controlling LocalEcho Modes Or Fax modeData and Fax Software manual Class 1 Fax Mode If the modem This indicates Returns a value 6CHAPTER 3 Modes of Operation DIALING, ANSWERING, Hanging UP DialingDial options Atdr ATD@ATD Atdl Enable carrier loss redial Command does. Also can be used to repeat anyDisable carrier loss redial Redialing This command also defines the interval in seconds ATA Force Answer ModeGo through the answer sequence when it hasnt Received an incoming call Manually answer a call International calls If you want your modem CommandMaking International calls above 1200 bps Call Detection Make/Break RatioPulse dialing Caller ID Functions Modem Handles Caller ID AT#CID=0 Caller ID Action CommandAn Example of Unformatted caller ID presentation AT#CID=1 Distinctive Ring SupportReferences Are graphical depictions of each ring pattern.These CommandsThere are four ring patterns in common use Ring Result Codes Verbal Numeric Memory type Applies to Loss of power will Command Working with MemoryNVRAM, and Flash memory Saving a Phone Number to Nvram ATDS2 AT&F0 Saving a Command String to NvramDisplaying S-Register Value Information AT&F1 Substitute a template other than &F1 AT&F2&W Additional Result Code subsets CommandsControlling Result Code Displays What format they are displayed AT&A1 Additional Result Code SubsetsAT&A0 AT&A2 Data Terminal Controlling EIA-232 SignalingTells the modem how to respond to the DTR signal Ready Signal Data Set Ready AT&C0 Business Modem sends the CD signalCarrier Detect AT&C1 4CHAPTER 7 Controlling EIA-232 Signaling Controlling Data Rates Serial Port Rates To allow your modem Set the serial port Command Rate as AT&B0AT&B2 AT&N9 AT&N0AT&N1 AT&N2 Speeds Command ValuesSpeeds with &N and &U AT&N To limit Use this command Where x is Lowest possible connect If &U Then your modem Link Speed Index Kbps Enhance throughput46666 48000 49333 50666 52000 53333 54666 56000 57333 8CHAPTER 8 Controlling Data Rates Its configuration remotely Accessing and Configuring Business Modem RemotelySetting Up Remote Access You should be familiar with these terms before you continue AT%P0=password Accessing the Host Configuration computer You should see a display similar to this AT%B1 AT%B0AT%B6 AT%B7 You can use the AT%Fn command to control the data format Commands Remote-AccessPassword, return online by pressing CtrlC or typing ATO Quitting aPage Dial Security Setting up Dial Security To make the host Business Command Example Modem For your modem to Command ExampleAT%L AT%L=PW0 Enable Local Security Enabled When using Autopass Prompting When using Password Prompting For your modem to enable Command Dial Security with Password PromptingAutopass Dial Security Security Accounts Example Sending AT%E=3 erases passwords for accountsMaintaining Account information User Needs to Do For your modem to Command Enable Dial SecurityWhat the Guest Dial Security by entering ATS53.0=1 Security Remotely For your modem to be set CommandFor your modem to Command Disable Auto Answer Dialing In From the Remote Site 10-10CHAPTER 10 Dial Security Received-data flow control Flow ControlHardware and software flow control Transmit-data flow control Hardware Software FlowControl AT&R2 AT&R0AT&R1 AT&I1 AT&I4 Enable Hewlett Packard-Terminal mode. Applies only toDoes not look for your typed XON/XOFF commands Characters from the data stream Transmit-Data Flow By its attached computer 11-6CHAPTER 11 Flow Control HANDSHAKING, Error Control Data COMPRESSION, Throughput Handshaking Attaining 56 K Connections For your modem to Command Enable the call indicate toneAttaining Speeds Above 28.8 Kbps Controlling the V.8 Call Indicate Tone Capabilities EnableDisable Other Protocols Leveling ASL Lower-speed Error ControlError-Control Protocols AT&M0 Have no error control Normal ModeAsynchronous Mode AT&M4 Two reasons Scheme similar to MNPFlow Control Remote end until it is acknowledged by the receiving device AT&K2 For the modem to CommandAT&K0 AT&K3 Maximum Getting MaximumThroughput Throughput results Public Domain Effects Getting Maximum Throughput Page Querying Here is a complete list of ATI n commandsDisplaying Querying and Help Screens Product code, and call duration ATI7 ATI2ATI3 ATI11 For your modem to display Command AT$ 13-4CHAPTER 13 Displaying Querying and Help Screens Testing the Business Modem using S-Register Testing the ConnectionTesting the Business Modem using AT&Tn All loopback testing conforms to ITU-T Recommendation Testing the Business Modem usingAT&Tn Using AT&T1 Using AT&T8 Loopback DL testing There are two remote digital loopback options AT&T6, AT&T7Phone line. Data flow is shown in the figure below Request AT&T4 Testing Using Keyboard Data AT&T6 14-8CHAPTER 14 Testing the Connection Remote digital loopback using keyboard data Testing the Business Modem using S-ResisterFor your modem to use Use one of these command Remote digital loopback with built-in test pattern Testing Using Keyboard Data ATS16=8 When S16 is set to 4, the Business Starting Testing That Uses the Test PatternTo use the test pattern during Command Testing with Register 14-12CHAPTER 14 Testing the Connection Troubleshooting Problems That Occur Before Connecting For your modem to Command Enable message display Business Modem wont dialDisplay verbal messages Double characters are appearing on your monitor Hear ringing but the Business Modem wont answer Problems that Occur After Connecting Your screen displays random or garbage characters Mainframe computer keeps dropping your connection Errors during software download If You Still Have Problems Problems that Occur After Connecting 15-8CHAPTER 15 Troubleshooting Upgrading Your Modem Checking Your Business Modem’s Software Version Sending New Getting NewOperating Software Software to your Enter AT~X!. The modem should respond as follows If Your Modem Doesn’t Respond Mapped to decimal RegistersHow bits are Values 01001111 Converting Bits toDecimal Values 113 Settings Using BitsUsing Decimal Values of the bits and entering the total Bit-mapped registers have up to eight functions Register Default Function Complete list of S-Registers Bit Value Result Off their screens. When remote Be a problem if you expect a greatNumber of errors during a call Information about setting bit-mapped registers. For Default is 3 seconds Up. S19=0 disables the timerTo ARQ mode only Enable ITU-T V.21 modulation at Bit Result Thus enabling or disabling remote access Disable the remote-access busy128 Disable V.32 terbo S38 Default setting of zero allows no remote login Enabled Dial security enabledPrompting enabled Disable 2400 symbol rate Disable V.34+ Disable precodingDisable shaping 128 Disable V.FC S58 Alphabetic Command Summary Basic Command SetCommand Function Optional parameters Display help for the dial commands When other modems share the lineStore the number in memory using the &Z command Command mode echo ON. Your typing will Between command and online modes Display the actual time. Set the clock usingControl when the speaker sounds Errors in a non-ARQ data transfer Ampersand Command Set With the Hn command CD when it disconnectsMode during a call by dropping DTR DTR signal. Dropping DTR ends a call Mode only Software support XON/XOFF signalingRecommended setting for ARQ mode Error control. For this to work, the remote device Negotiates only for V.42bis compression, This setting to transfer compressed filesSelective data compression. The modem Line type Normal Ampersand & Command Set B-9 Originate mode Send DSR after dialing, on Enable hardware flow control of received dataSend the computer a Data Set Ready DSR signal via When Carrier is lost, send a pulsed DSR signal Percent % Command Set B10 115200 bps Remote configuration control Create and configure security accountsRemotely configure a modems serial port rate Cancel configuration changes and restore Octothorpe # Command Set 14APPENDIX B Alphabetic Command Summary Flow Control Template Hardware FlowTemplate send AT&F1 to your modem None DTE rate* Kbps19.2 Template send AT&F2 to the modem Software flow control Basic Even 9600 6APPENDIX C Flow Control Template Result Code Meanings Sets Result Code MeaningsResult Code Meaning Functions Result Codes Sets for Xn Values10/CONNECT Wait for 2nd Dial Tone W Wait for Answer @ Technical SpecificationsTechnical Information Schemes are supported Adheres to the following standards Error Control, DataDialing This Supports This feature Supports AdditionalWord Length Parity 1 Bit Stop Bits Pin Function Transmitted Data Received Data Signal Ground Operate asynchronously followsDB-25 DB-9 Most reliable performance Mac Pin Mac Pin Description Modem Pin Modem Pin Description Macintosh modem Ascii Chart 2APPENDIX F Ascii Chart Following optional Class 2.0 fax commands Fax Service Class 1 CommandsFAX Service Class FAX Information for Programmers Fax Mode Flow Control SettingFCC Notice This LED Status Means your Business Modem Is making a data connection using an error controlViewing Leds Protocol Off RS232 mode has not detected DTR RS232 mode has detected DTR signalUSB mode has detected successful USB registration Off Has not detected the RTS signal from your computer Character. Valid range is 0*127 Registers Their Functions and Default SettingsCounts and stores the number of rings from an incoming Valid range is 0*127 At power-on/reset, autodial number Disable 250 ms pause before resultOn DTR signal, autodial the number Disable HST From 1.5K bytes to 128.* for Problem if you expect a greatFor HST modulation only Calls from remote users of slower Disable V.32 modulation used for Line, and at the timeout the Business Modem hangs upS19=0 disables the timer Remote digital loopback Register Default Function Bit Value Result To acknowledge receipt of all transmitted data. Default = Disable the faster retrains that occur128 Disable V.32terbo S38 Thus enabling or disabling remote access. The default Disable V.8 Call Indicate CI 128 Enable phase roll detectionReserved Enable ring type B Disable preemphasisEnable ring type a Enable ring type C Warranty Corporation Limited Warranty 3Com Client SRO# 3COM Corporation Limited Warranty J-3 FCC Registration FCC CertificationStatement FCC Notice Radio Television Interference Canada Glossary Glossary Glossary Glossary Glossary Glossary Glossary Glossary Glossary Glossary Transmission rate See it rate Receiver/Transmitter Glossary Glossary Glossary