If &U Then your modem | 3Com 56K guide

Controlling Link Speeds with &N and &U 8-5

Limiting the Lowest The &U command allows you to limit the lowest possible connect speed. Possible Connect If a remote modem attempts to connect to your Business Modem at a

Speed speed lower than &U, your Business Modem will not allow it to connect.

To limit the	Use this command	Where x is

Lowest possible connect	AT&U=x	A value from 0 to 32
speed

See the table in the section &N and &U Command Values for connect speed values.

Limiting a Range of By setting &N and &U values, you can limit the range of speeds at which Possible Connect your Business Modem connects. If a remote modem does not connect to Speeds your Business Modem at a range between the speeds designated by the

&N and &U commands, your Business Modem will not allow it to connect.

The link speed associated with the &U argument CANNOT be greater than the link speed associated with &N argument.

Use the following table to understand the relationship between &U and &N commands:

If &U	And &N	Then your modem

Equals zero	Equals zero	Connects at the highest possible
		speed.

Equals zero	Is greater than zero	Connects at the &N speed only.

Is greater than zero	Is greater than zero and	Connects at the highest possible
	greater than &U	speed in the range from &U to &N.

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3Com 56K manual To limit Use this command Where x is Lowest possible connect, If &U Then your modem

Contents

3Com OfficeConnect 56K Business Modem Command Reference United States Government Legend 3Com Corporation 3800 Golf Rd Rolling Meadows, Illinois Contents Command and Online Modes If You Are Using MS-DOSOther Operating Systems Making International calls Overview Result Code Display Commands Additional Result Code SubsetsData Terminal Ready Data Set Ready Carrier Detect Overview Serial Port Rates Connection Rates Setting up Dial Security Setting DTE Rate to 230 KbpsPassword Prompting Remote Configuration MNP Error Control Error ControlTesting the Business Modem using AT&Tn Received Data Flow Control Remote Digital Loopback Testing AT&T6, AT&T7 Digital Loopback Testing AT&T3Canceling All Digital Loopback Test Requests &T5 Testing Using Keyboard Data AT&T6 Sending New Software to your modem Getting New Operating SoftwareIf Your Modem Doesn’t Respond Hardware Flow Control Software Flow control No Flow Control Additional Specifications Serial Ports Serial Ports Macintosh modemRegisters Introduction About this GuideFinding Specific Information This Guide Icon Description ConventionsConvention Description Wait n seconds between losing the connection Related About this Guide Windows 95/98 Connecting to Your ISP 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 TCP/IP Settings Step Four Customizing the TCP/IP SettingsClick OK, and OK If your ISP Do this Click Server assigned IP address Specify an IP address, if neededClick Specify name server addresses and enter Click Server assigned server address For you to Use this connection Setting up RAS Go to Start Settings Control Panel ModemsSelect Remote Access Service and click Properties Check Don’t detect my modem I will select it from a list Select Start Settings Control Panel Click Continue to complete RAS setupGo to Start Programs Accessories Dial Up Networking 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 Installation Script and then configure Open Transport PPP System Configuration Accessing InternetInstalling the script Slip or PPP dialing software Transport PPP Go to Apple Menu Control Panels Modem Macintosh Go to Apple Menu Control Panels PPP Other Operating If You Are UsingSystems Windows 18CHAPTER 1 Connecting to Your ISP Using AT commands Using the AT Command SETOverview General rules for To configure your modem to Command Dial the following number using tone dialingRe-execute the last-issued command Use the X2 result code subset To display Command Settings for a register in the current configurationTo change Command ATI5 Bit-mapped UnderstandingRegisters Getting a list Registers If you want to Set the modem to Use this command Command and Online ModesModes of Operation ATO0 Mode If you want to Command Return onlineReturn online and retrain ATO1 Online Mode Controlling LocalEcho Data and Fax Or Fax modeModes Software manual If the modem This indicates Returns a value Class 1 Fax Mode 6CHAPTER 3 Modes of Operation DIALING, ANSWERING, Hanging UP DialingDial options ATD ATD@Atdr Atdl Disable carrier loss redial Command does. Also can be used to repeat anyEnable carrier loss redial Redialing This command also defines the interval in seconds Go through the answer sequence when it hasnt Force Answer ModeATA Received an incoming call Manually answer a call Making If you want your modem CommandInternational calls International calls above 1200 bps Call Detection Make/Break RatioPulse dialing Caller ID Functions Caller ID Modem Handles An Example of Unformatted caller ID presentation Caller ID Action CommandAT#CID=0 AT#CID=1 Distinctive Ring SupportReferences There are four ring patterns in common use CommandsAre graphical depictions of each ring pattern.These Ring Verbal Numeric Result Codes Memory type Applies to Loss of power will Command Working with MemoryNVRAM, and Flash memory ATDS2 Saving a Phone Number to Nvram Displaying S-Register Value Information Saving a Command String to NvramAT&F0 AT&F1 AT&F2&W Substitute a template other than &F1 Controlling Result Code Displays CommandsAdditional Result Code subsets What format they are displayed AT&A0 Additional Result Code SubsetsAT&A1 AT&A2 Tells the modem how to respond to the DTR signal Controlling EIA-232 SignalingData Terminal Ready Data Set Ready Signal Carrier Detect Business Modem sends the CD signalAT&C0 AT&C1 4CHAPTER 7 Controlling EIA-232 Signaling Serial Port Rates Controlling Data Rates To allow your modem Set the serial port Command Rate as AT&B0AT&B2 AT&N1 AT&N0AT&N9 AT&N2 Speeds with &N and &U Command ValuesSpeeds AT&N If &U Then your modem To limit Use this command Where x is Lowest possible connect Link Speed Index Kbps Enhance throughput46666 48000 49333 50666 52000 53333 54666 56000 57333 8CHAPTER 8 Controlling Data Rates Setting Up Remote Access Accessing and Configuring Business Modem RemotelyIts configuration remotely You should be familiar with these terms before you continue AT%P0=password Accessing the Host You should see a display similar to this Configuration computer AT%B6 AT%B0AT%B1 AT%B7 You can use the AT%Fn command to control the data format Password, return online by pressing CtrlC or typing ATO Remote-AccessCommands Quitting aPage Dial Security Security Setting up Dial To make the host Business Command Example Modem For your modem to Command ExampleAT%L AT%L=PW0 Enabled Enable Local Security When using Autopass Prompting When using Password Prompting For your modem to enable Command Dial Security with Password PromptingAutopass Dial Security Maintaining Example Sending AT%E=3 erases passwords for accountsSecurity Accounts Account information What the Guest For your modem to Command Enable Dial SecurityUser Needs to Do Dial Security by entering ATS53.0=1 For your modem to Command Disable Auto Answer For your modem to be set CommandSecurity Remotely Dialing In From the Remote Site 10-10CHAPTER 10 Dial Security Hardware and software flow control Flow ControlReceived-data flow control Transmit-data flow control Hardware Software FlowControl AT&R1 AT&R0AT&R2 AT&I1 Does not look for your typed XON/XOFF commands Enable Hewlett Packard-Terminal mode. Applies only toAT&I4 Characters from the data stream By its attached computer Transmit-Data Flow 11-6CHAPTER 11 Flow Control Handshaking HANDSHAKING, Error Control Data COMPRESSION, Throughput Attaining Speeds Above 28.8 Kbps For your modem to Command Enable the call indicate toneAttaining 56 K Connections Controlling the V.8 Call Indicate Tone Disable EnableCapabilities Other Protocols Leveling ASL Error-Control Error ControlLower-speed Protocols Asynchronous Mode Have no error control Normal ModeAT&M0 AT&M4 Flow Control Scheme similar to MNPTwo reasons Remote end until it is acknowledged by the receiving device AT&K0 For the modem to CommandAT&K2 AT&K3 Throughput Getting MaximumMaximum Throughput results Public Domain Effects Getting Maximum Throughput Page Displaying Querying and Help Screens Here is a complete list of ATI n commandsQuerying Product code, and call duration ATI3 ATI2ATI7 ATI11 AT$ For your modem to display Command 13-4CHAPTER 13 Displaying Querying and Help Screens Testing the Business Modem using AT&Tn Testing the ConnectionTesting the Business Modem using S-Register All loopback testing conforms to ITU-T Recommendation Testing the Business Modem usingAT&Tn Using AT&T1 Using AT&T8 Loopback DL testing Phone line. Data flow is shown in the figure below AT&T6, AT&T7There are two remote digital loopback options Request AT&T4 Testing Using Keyboard Data AT&T6 14-8CHAPTER 14 Testing the Connection For your modem to use Use one of these command Testing the Business Modem using S-ResisterRemote digital loopback using keyboard data Remote digital loopback with built-in test pattern Testing Using Keyboard Data ATS16=8 To use the test pattern during Command Testing with Starting Testing That Uses the Test PatternWhen S16 is set to 4, the Business Register 14-12CHAPTER 14 Testing the Connection Problems That Occur Before Connecting Troubleshooting For your modem to Command Enable message display Business Modem wont dialDisplay verbal messages Hear ringing but the Business Modem wont answer Double characters are appearing on your monitor Your screen displays random or garbage characters Problems that Occur After Connecting Mainframe computer keeps dropping your connection If You Still Have Problems Errors during software download Problems that Occur After Connecting 15-8CHAPTER 15 Troubleshooting Checking Your Business Modem’s Software Version Upgrading Your Modem Operating Software Getting NewSending New Software to your Enter AT~X!. The modem should respond as follows Doesn’t Respond If Your Modem How bits are RegistersMapped to decimal Values Decimal Values Converting Bits to01001111 113 Using Decimal Using BitsSettings Values of the bits and entering the total Bit-mapped registers have up to eight functions Complete list of S-Registers Register Default Function Bit Value Result Number of errors during a call Be a problem if you expect a greatOff their screens. When remote Information about setting bit-mapped registers. For To ARQ mode only Up. S19=0 disables the timerDefault is 3 seconds Enable ITU-T V.21 modulation at Bit Result 128 Disable V.32 terbo S38 Disable the remote-access busyThus enabling or disabling remote access Default setting of zero allows no remote login Prompting enabled Dial security enabledEnabled Disable 2400 symbol rate Disable shaping Disable precodingDisable V.34+ 128 Disable V.FC S58 Alphabetic Command Summary Basic Command SetCommand Function Optional parameters Store the number in memory using the &Z command When other modems share the lineDisplay help for the dial commands Command mode echo ON. Your typing will Control when the speaker sounds Display the actual time. Set the clock usingBetween command and online modes Errors in a non-ARQ data transfer Ampersand Command Set Mode during a call by dropping DTR CD when it disconnectsWith the Hn command DTR signal. Dropping DTR ends a call Recommended setting for ARQ mode Software support XON/XOFF signalingMode only Error control. For this to work, the remote device Selective data compression. The modem This setting to transfer compressed filesNegotiates only for V.42bis compression, Line type Normal Ampersand & Command Set B-9 Send the computer a Data Set Ready DSR signal via Enable hardware flow control of received dataOriginate mode Send DSR after dialing, on When Carrier is lost, send a pulsed DSR signal Percent % Command Set Remotely configure a modems serial port rate Create and configure security accountsB10 115200 bps Remote configuration control 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 Software flow control Template send AT&F2 to the modem Basic 9600 Even 6APPENDIX C Flow Control Template Result Code Meanings Sets Result Code MeaningsResult Code Meaning 10/CONNECT Result Codes Sets for Xn ValuesFunctions Wait for 2nd Dial Tone W Wait for Answer @ Technical Information SpecificationsTechnical Schemes are supported Dialing Error Control, DataAdheres to the following standards 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 Mac Pin Mac Pin Description Modem Pin Modem Pin Description Most reliable performance Macintosh modem Ascii Chart 2APPENDIX F Ascii Chart FAX Service Class Fax Service Class 1 CommandsFollowing optional Class 2.0 fax commands FAX Information for Programmers Fax Mode Flow Control SettingFCC Notice Viewing Leds Is making a data connection using an error controlThis LED Status Means your Business Modem Protocol USB mode has detected successful USB registration RS232 mode has detected DTR signalOff RS232 mode has not detected DTR Off Has not detected the RTS signal from your computer Counts and stores the number of rings from an incoming Registers Their Functions and Default SettingsCharacter. Valid range is 0*127 Valid range is 0*127 On DTR signal, autodial the number Disable 250 ms pause before resultAt power-on/reset, autodial number Disable HST For HST modulation only Problem if you expect a greatFrom 1.5K bytes to 128.* for Calls from remote users of slower S19=0 disables the timer Line, and at the timeout the Business Modem hangs upDisable V.32 modulation used for Remote digital loopback Register Default Function Bit Value Result 128 Disable V.32terbo S38 Disable the faster retrains that occurTo acknowledge receipt of all transmitted data. Default = Thus enabling or disabling remote access. The default Disable V.8 Call Indicate CI 128 Enable phase roll detectionReserved Enable ring type a Disable preemphasisEnable ring type B Enable ring type C Corporation Limited Warranty 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 Receiver/Transmitter Transmission rate See it rate Glossary Glossary Glossary