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Error Control

12-7

V.42 Error Control

The Business Modem first tries for a V.42 connection, then an MNP
connection. The following information is based on the Business Modem's
setting of &M4.

This international standard includes a two-stage hand-shaking process:

■

A

Detection

phase that is based on an exchange of predefined

characters.

■

A

Link Access Procedures for Modems (LAPM) Negotiation

phase, during which the devices identify their capabilities concerning
maximum data block size and the number of outstanding data blocks
allowed before an acknowledgment is required.

MNP Error Control

The Microcom Networking Protocol (MNP) is supported by the ITU-T V.42
Recommendation. MNP is based on special protocol frames. If the remote
device doesn't recognize an MNP Link Request, error control isn't
possible. (In HST asymmetrical mode, 3Com devices use a proprietary
scheme similar to MNP.)

Error Control and

Flow Control

Flow control of data from the computer is required under error control for
two reasons:

■

The transmitting device buffers a copy of each frame it transmits to
the remote end until it is acknowledged by the receiving device.

■

If errors are encountered, retransmission activity can cause a steady
stream of data from the computer to overflow the buffer.

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Содержание OfficeConnect 56K Business

Страница 1: ... http www 3com com 3Com OfficeConnect 56K Business Modem Command Reference Published January 1999 ...

Страница 2: ...omputer Software as defined in DFARS 252 227 7014 June 1995 or as a commercial item as defined in FAR 2 101 a and as such is provided with only such rights as are provided in 3Com s standard commercial license for the Software Technical data is provided with limited rights only as provided in DFAR 252 227 7015 Nov 1995 or FAR 52 227 14 June 1987 whichever is applicable You agree not to remove or d...

Страница 3: ...our Internet Service Provider 1 2 Windows NT 4 0 and Later 1 8 What you need 1 9 Configuring Your modem 1 9 Setting up RAS 1 9 Determining if TCP IP is installed 1 10 Installing TCP IP 1 10 Configuring a PPP connection 1 10 Configuring a SLIP connection 1 11 Troubleshooting RAS 1 12 Macintosh 1 12 Handshaking Cable 1 12 System Configuration 1 13 Accessing the Internet 1 13 Macintosh 230K High Spee...

Страница 4: ...n S Register 2 3 Getting a list of S Registers 2 4 Understanding bit mapped S Registers 2 4 3 MODES OF OPERATION Command and Online Modes 3 1 Entering Online Command Mode 3 2 Returning to Online Mode 3 2 Controlling Local Echo 3 3 Command Mode Local Echo 3 3 Online Mode Local Echo 3 3 Data and Fax Modes 3 4 4 DIALING ANSWERING AND HANGING UP Dialing 4 1 Dial options 4 1 Carrier Loss Redial 4 3 Ans...

Страница 5: ...ng with RAM and NVRAM 5 2 Saving a Phone Number to NVRAM 5 2 Displaying S Register Value Information 5 3 Saving a Command String to NVRAM 5 3 Working with Flash Memory 5 3 Saving ROM Templates to NVRAM 5 4 Default Settings 5 4 6 CONTROLLING RESULT CODE DISPLAYS Result Code Display Commands 6 1 Additional Result Code Subsets 6 2 7 CONTROLLING EIA 232 SIGNALING Data Terminal Ready 7 1 Data Set Ready...

Страница 6: ...m 9 1 Other Remote Access Commands 9 3 Accessing the Host 9 3 At the Guest Device 9 3 Viewing and Changing the Host s Configuration 9 4 Remote Configuration Commands 9 5 Quitting a Remote Access Session 9 7 10 DIAL SECURITY Overview 10 1 Setting up Dial Security 10 2 Dialback options 10 3 Modifying Accounts 10 4 Autopass Prompting 10 5 Password Prompting 10 5 Maintaining Security Accounts 10 7 Rem...

Страница 7: ... 4 Lower speed V Protocols 12 5 Error Control 12 5 Error Control Commands 12 5 V 42 Error Control 12 7 MNP Error Control 12 7 Error Control and Flow Control 12 7 Data Compression 12 8 V 42bis versus MNP5 Data Compression 12 8 Getting Maximum Throughput 12 9 Maximum throughput results when 12 9 13 DISPLAYING QUERYING AND HELP SCREENS Overview 13 1 Querying 13 1 Displaying Help 13 3 14 TESTING THE C...

Страница 8: ...15 2 Double characters are appearing on your monitor 15 3 After you dial the Business Modem reports NO CARRIER and then hangs up 15 3 Hear ringing but the Business Modem won t answer 15 3 The Business Modem acts as though a data link has been established but no call was received 15 3 The Business Modem behaves as if Enter were pressed when you don t press any keys 15 3 Problems that Occur After Co...

Страница 9: ...ng Decimal Values A 3 Default S Register Settings A 3 A complete list of S Registers A 5 B ALPHABETIC COMMAND SUMMARY Basic Command Set B 1 Ampersand Command Set B 5 Percent Command Set B 11 Octothorpe Command Set B 13 C FLOW CONTROL TEMPLATE Hardware Flow Control C 1 Software Flow control C 3 No Flow Control C 4 D RESULT CODE MEANINGS AND SETS Result Code Meanings D 1 Result Codes Sets for Xn Val...

Страница 10: ... FAX INFORMATION FOR PROGRAMMERS Fax Service Class 1 Commands G 1 FAX Service Class 2 0 Commands G 1 Fax Mode Flow Control Setting G 2 FCC Notice G 2 Notes G 2 H VIEWING LEDS I S REGISTERS S Registers I 1 J WARRANTY 3Com Corporation Limited Warranty J 1 Notices J 4 FCC Certification Statement J 4 FCC Registration J 4 FCC Notice J 4 FCC Notice Radio and Television Interference J 5 IC Industry Canad...

Страница 11: ... this guide follow the instructions in the release notes Finding Specific Information in This Guide This table shows the location of specific information in this guide If you are looking for information about Turn to Connecting to your ISP Chapter 1 Upgrading Your Busniess Modem Chapter 3 Basic AT Commands Chapter 2 Display Querying and Help Screens Chapter 14 Testing a Connection Chapter 15 Troub...

Страница 12: ...orm of a command in uppercase and lowercase letters However you can abbreviate commands by entering only the uppercase letters and the appropriate value Commands are not case sensitive Screen displays This typeface represents information as it appears on the screen The words enter and type When you see the word enter in this guide you must type something and then press the Return or Enter key Do n...

Страница 13: ...0 Compliance For information on Year 2000 compliance and 3Com products visit the 3Com Year 2000 web page http www 3com com products yr2000 html Words in italicized type Italics emphasize a point or denote new terms at the place where they are defined in the text Words in bold face type Bold text denotes key features Table 2 Text Conventions continued Convention Description ...

Страница 14: ...4 ABOUT THIS GUIDE ...

Страница 15: ...ill not recognize your modem What You Need You need Windows 95 98 with Dial Up Networking installed to configure your modem for Windows 95 98 Configuring Your modem with Plug and Play Plug and Play mode allows Windows 95 98 to automatically detect your modem and determine which modem configuration file called an INF file to use Follow the steps below to install the INF file for Windows 95 98 1 Pow...

Страница 16: ...ou use the latest version of the modem software and information INF file from the 3Com U S Robotics Web site http www usr com home online Installing the Latest Software See Chapter 3 Upgrading your Modem for information about upgrading your Business Modem s software Accessing Your Internet Service Provider This section explains how to set up your modem to access the Internet or remote Local Area N...

Страница 17: ...to the Control Panel and double click on Add Remove Programs to open the Add Remove Programs Properties window 4 Click Windows Setup tab 5 Double click on Communications The following window appears 6 Click on Dial Up Networking to check the box 7 Click OK OK If Dial Up Adapter Do this Is listed Go to the section Installing TCP IP Support to install Dial Up Networking Is not listed Go to Step 3 ...

Страница 18: ...ted 4 Type a name for the connection and click Next 5 Type a phone number for the connection and click Next 6 You should see a message indicating that a new connection was created successfully 7 Click Finish 8 A New Connection icon will be created in the Dial Up Networking Window Move your cursor to the new icon you have just created and click the right mouse button Select Properties on the menu t...

Страница 19: ...Windows 95 98 1 5 9 On the My Connection window click Server Type and deselect the following Log on to Network NetBEUI IPX SPX Compatible ...

Страница 20: ...ouble click My Computer and double click Dial Up Networking to display all the connections you can customize 2 Right click the icon you created and select Properties to display the My Connection properties window 3 On the My Connection properties window click the Server Type tab 4 Click TCP IP Settings If your ISP Do this Gives you a specific IP or Domain Name server addresses Go to Step Four Cust...

Страница 21: ...ddress Click Specify an IP address and enter the IP address provided by your ISP Does not give you a specific IP address Click Server assigned IP address If your ISP Do this Gives you specific name server addresses Click Specify name server addresses and enter the server address es provided by your ISP Does not give you specific name server addresses Click Server assigned server address ...

Страница 22: ... for Windows NT users CAUTION Before you use these procedures contact your ISP to determine if they have any special requirements For you to Use this connection Use a dial up connection to connect over the Internet SLIP only allows you to connect using IP and does not allow for server assigned IP addresses or server assign name server addresses Serial Line Internet Protocol SLIP Use a dial up conn...

Страница 23: ... 1 Go to Start Settings Control Panel Modems 2 Click Add 3 Check Don t detect my modem I will select it from a list 4 Click Next 5 Click Have Disk 6 Place the diskette or CD ROM that was packaged with your Business Modem into your floppy disk or CD ROM drive Select the INF file found on the disk 7 Select the COM port for your Business Modem 8 When the installation is complete Windows NT will reque...

Страница 24: ...cols to find TCP IP Protocol Adapter 4 If TCP IP Protocol is listed skip to section Configuring a PPP Connection If TCP IP Protocol is NOT listed move to the next section Installing TCP IP To install TCP IP perform the following actions 1 Select Start Settings Control Panel 2 Double click Network 3 On the Protocol tab click Add and select the TCP IP protocol from the list Configuring a PPP connect...

Страница 25: ... address provided by your ISP 6 Enter the primary DNS and secondary DNS server IP addresses in the appropriate name server address boxes 7 If your ISP requests that you use a specific frame size select the desired frame size in the Frame Size box If your ISP Do this Gives you a specific IP address Click Specify an IP address and enter the IP address provided by your ISP Does not give you a specifi...

Страница 26: ... any authentication including clear text Make sure only the necessary network protocols are selected In the Connect to window after you click Dial there should be no domain set This is only for logging into NT domains Make sure that the TCP IP settings are correct This is a general setup for your Business Modem using Windows NT If you are having problems connecting to you ISP configuring Dial Up N...

Страница 27: ...usiness Modem and 25 mhz Business Modem you first must install the Macintosh 230K High Speed Script and then configure Open Transport PPP Installing the script 1 Download the USRARA HQX file This file can be found on the internet at http www usr com home online in the software library area It can also be downloaded from the BBS at 847 262 6000 2 After the file is downloaded it needs to uncompresse...

Страница 28: ...e system responds with a proper speed Configuring Open Transport PPP Selecting the correct modem 1 Go to Apple Menu Control Panels Modem 2 In the Modems Window choose the port that your modem is connected to in the Connect via drop down box 3 Select the correct modem in the Modem drop down box ...

Страница 29: ...rol Panel TCP IP 2 In the TCP IP window select PPP in the Connect via drop down box 3 Set the Configure drop down box to Using PPP Server 4 Type in your internet service providers Domain Name Server Address DNS numbers in the Name server addr box 5 Leave the other fields empty ...

Страница 30: ... Panels PPP 2 In the PPP window select Registered User 3 Type in your Internet Service providers login name and your password in the name and password boxes 4 Put the phone number that you dial to connect to your internet provider in the number box You ve successfully configured Open Transport PPP ...

Страница 31: ...00 bps it is recommended that you use a third party communications software package If You Are Using MS DOS Because there is no communications software built in to MS DOS you must install and run a third party communications software package to operate your modem RapidComm which is included on the Connections CD ROM contains MS DOS and Windows 3 1 versions of RapidComm You must choose the COM port...

Страница 32: ...1 18 CHAPTER 1 CONNECTING TO YOUR ISP ...

Страница 33: ...erminal mode what you type is sent directly to the modem General rules for using AT commands You must follow some general guidelines to send AT commands to your modem Type AT before each command and press ENTER after each command The exceptions are A A and which require neither AT nor ENTER Leave zeroes off the end of AT commands A missing numeric parameter is assumed to be a zero For example ATE ...

Страница 34: ...iming parameters redefinitions of selected ASCII characters and other configuration settings are stored Initially the S Register settings for each of the NVRAM templates are the same You can overwrite an S Register s stored value See the default values listed in Appendix A S Registers for a complete listing of the initial settings AT Attention a command follows K3 Disable MNP5 data compression use...

Страница 35: ...manually CAUTION If you do not write an S Register setting with W the setting will be retained only until the next reset or power off Example Sending ATS0 2 changes the setting for S Register 0 to 2 This setting will cause the Business Modem to answer in Auto Answer Mode on the second ring In the command ATSr n r is the register s number and n is a decimal value from 0 255 unless otherwise indicat...

Страница 36: ...bit mapped S Register uses one number to describe a collection of settings Bit mapping allows us to pack a lot of information in a small space Bit mapped registers are in the form of Sr b n where r is the bit mapped register b is the bit n is 0 off or 1 on See Appendix A S Registers to see how bits are mapped into decimal values and for information about setting bit mapped S Registers To display C...

Страница 37: ... Set the modem to Use this command Control the modem using AT commands Command Mode Escape Code Your modem set to revert to Command Mode when the Escape Code is used ATS14 0 0 Your modem to Disconnect when the Escape Code is used ATS14 0 1 Return to your connection after an Online Command Mode session Online Mode ATO0 Send the modem commands while you are on line with another device Online Command...

Страница 38: ...data 6 Type 7 Wait for OK to appear before typing any data You can change the characters used to revert to Command Mode or the wait time by resetting Register S2 or S12 For more information about resetting these S Registers see Appendix A S Registers Returning to Online Mode There are two ways to return online using the ATOn command Example Sending ATO1 will allow you to resynchronize if you exper...

Страница 39: ... transmitted on your screen you can use the ATFn command Example Sending ATF0 will allow you to see what you are typing in the display window You may see the term duplex used in place of online local echoing although the term is not technically accurate If you want the commands you type to Command NOT appear on screen Command Mode echo OFF ATE0 Appear on your screen Command Mode echo ON ATE1 As th...

Страница 40: ...n you exit the program Example Sending AT FCLASS 1 allows you to receive faxes from fax machines Class 1 and Class 2 0 Fax Modes refer to standards set by the Electronic Industries Association Telecommunications Industry Association Class 1 Fax Mode is the minimal standard for computer faxmodem interface Class 2 0 Fax Mode refers to the extended computer faxmodem interface If you want the modem pr...

Страница 41: ...s in Data or Fax mode use the AT FCLASS command Whenever the modem is reset using the ATZ command or by turning the power off and then on it will reset to Data Mode If the modem returns a value of This indicates 0 Data Mode 1 Class 1 Fax Mode 2 0 Class 2 0 Fax Mode ...

Страница 42: ...3 6 CHAPTER 3 MODES OF OPERATION ...

Страница 43: ...ed phone number and execute dial options DO NOT use spaces or dashes ATD phone number Tone dial ATDT Pulse dial ATDP Pause for the length of time specified by S Register 8 The default is 2 seconds ATD Comma Pause for 125 milliseconds ATD Slash Wait for a second dial tone before continuing dialing This command only works only if the X3 or higher command has been issued see Chapter 7 Controlling Res...

Страница 44: ...dditional command IMPORTANT With the exception of the above Dial options your modem will ignore any commands issued after the D in the same command string Call a device that can only originate calls It forces the modem to dial out at the answer frequency or Reverse frequencies You can put the R either before or after the number ATDR Display different sets of result codes See Chapter 6 Controlling ...

Страница 45: ...conds then redial Make a maximum of 10 attempts To stop the repeating press any key during the pause between dial attempts If you press any key while the modem is dialing that dial attempt is canceled but the cycle will continue Dial the last dialed number and repeat it just as the command does Also can be used to repeat any command A For your modem to Command For your modem to Command Disable car...

Страница 46: ...nnection If there is no response within 60 seconds the Business Modem hangs up For more information about adjusting the 60 second wait for connection time using S Register 7 see Appendix A S Registers When a call is disconnected the Business Modem hangs up and returns the NO CARRIER result code If S0 0 Auto Answer is disabled To determine if Auto Answer is NOT disabled send the command ATI4 and be...

Страница 47: ...for making analog international calls above 1200 bps Handshaking options The ATBn command controls the handshake options Example Sending ATB1 will allow your modem to use Bell answer tone selecting HST modulation If you want your modem Command To answer all V 34 type calls as well as calls from overseas use ITU T formerly CCITT answer sequence ATB0 Default NOT to answer V 34 type calls Use Bell an...

Страница 48: ...l Detection Call Detection allows the modem to recognize whether an incoming call is analog data or fax Call Detection is an optional Service Class 2 0 feature and is also implemented by 3Com for Fax Class 1 applications To set your modem for Command Required in these countries No guard tone AT G0 Default United States and Canada 550 Hz guard tone AT G1 Some European countries 1800 Hz guard tone A...

Страница 49: ... associated with the calling party s telephone number in addition to the Basic service information The information the Business Modem actually receives depends on the service type to which you ve subscribed the information that the calling party s telephone company provides and whether the equipment in between supports caller ID At minimum you will always receive the date and time that a call arri...

Страница 50: ...15 TIME 2038 NMBR 8475550001 NAME U S ROBOTICS OK Using the CID command described below you can have the Business Modem send the information to your computer between the first and second RING messages The caller ID information is displayed only once RING DATE 1015 TIME 2038 NMBR 8475550001 NAME U S ROBOTICS RING The information remains in memory until either you reset the modem or until it receive...

Страница 51: ...nal An Example of Formatted caller ID presentation RING DATE 1015 TIME 2038 NMBR 8475550001 NAME U S ROBOTICS RING An Example of Unformatted caller ID presentation RING 801E01083130313532303338020A37303835353530303031070C552E532E 524F424F5449435322 RING Commands The following table describes the AT CID n settings Caller ID Action Command Disable Caller ID detection and reporting AT CID 0 Default E...

Страница 52: ...ber is associated with a different ring pattern and devices that recognize distinctive ring like the Business Modem can be set to answer only on certain incoming ring patterns For example a fax machine answering machine telephone and modem could all share the same line Each device would have its own phone number and respond only to calls intended for that number Enable Caller ID with formatted out...

Страница 53: ...0 seconds off C 0 4 second on 0 2 second off 0 4 second on 0 2 second off 0 8 second on 4 0 seconds off D 0 3 second on 0 2 second off 1 0 second on 0 2 second off 0 3 second on 4 0 seconds off For your modem to Command Enable recognition of Ring A ATS70 0 1 Disable recognition of Ring A ATS70 0 0 Enable recognition of Ring B ATS70 1 1 Disable recognition of Ring B ATS70 1 0 Enable recognition of ...

Страница 54: ...tical to that of other 3Com modems that do not support distinctive ring If only one ring type is enabled the Business Modem will recognize only the enabled ring type and ignore all others It will send the result code RING only when it detects the ring type that s enabled If more than one ring type is enabled the Business Modem will recognize only the enabled ring types and ignore the others When a...

Страница 55: ...ory RAM nonvolatile random access memory NVRAM and Flash memory Memory type Applies to Loss of power will Command RAM The current settings Cancel any changes you make To save settings before resetting the modem use W See the section Working with RAM for more detailed information ATI4 NVRAM Saved settings any configurations you can store retrieve and change NOT affect your settings ATI5 Flash Three...

Страница 56: ...he example above you would send AT N8 W to the modem The new default setting for your Business Modem will only allow a 14400 bps connection to a remote device To restore NVRAM factory defaults use the AT Fn command See Appendix B Alphabetic Command Summary for more information on setting Fn Saving a Phone Number to NVRAM CAUTION Do not include modem commands in AT Zn s Example To store the phone n...

Страница 57: ...lash memory You can use the Fn command to load one of the three configuration templates from Flash memory into current memory Example Sending AT F1 to your modem will load the Hardware Flow Control Template into RAM Memory For your modem to Command View the contents of a particular S Register ATSr where r is the number of the S Register For your modem to Command Store a command string in NVRAM The...

Страница 58: ...ttings When the Business Modem is turned on it loads the settings stored in NVRAM By default these settings are that same as the F1 template You can save any of the three templates or save modified versions of them in NVRAM for use as power on defaults See Appendix C Flow Control Templates for a complete listing of the default values For your modem to Command Example Display NVRAM settings F1 sett...

Страница 59: ...m to Command Display result codes ATQ0 NOT display result codes ATQ1 NOT display result codes while in Answer mode See Chapter 4 Modes of Operation for a description of modes ATQ2 Display result codes in numeric form ATV0 Display result codes in verbal form ATV1 Display result codes when originating answering and retaining a call ATS14 1 0 Display result codes ONLY when originating a call ATS14 1 ...

Страница 60: ...and A3 you won t be able to distinguish A2 from A3 codes For your modem to Command Display only connection rate AT A0 Display connection rate and ARQ result codes AT A1 Display connection rate ARQ result code and protocol information V32 VFC V34 or x2 v 90 If your software cannot handle the added protocol information select A1 or A0 AT A2 Display connection rate ARQ result code protocol error cont...

Страница 61: ...S stands for Recommended Standard For your modem to Command Ignore the state of DTR and act as if DTR is always present Use this command with equipment that cannot provide DTR AT D0 If issued before connecting with another device enter online Command Mode during a call by dropping DTR Most communications software packages have a method for toggling DTR Refer to your software s manual for details A...

Страница 62: ...modem Command To send the DSR signal at all times AT S0 Default When originating a call to send the DSR signal after dialing when the Business Modem detects the remote analog device s answer tone AT S1 When answering a call to send DSR after the Business Modem sends its answer tone AT S1 After sending Carrier Detect CD to send a pulsed DSR signal followed by a Clear to Send CTS signal Use this opt...

Страница 63: ...sends a Carrier Detect CD signal in response to establishing a connection with another modem You can use the AT Cn command to control how the Business Modem sends the CD signal For your modem to Command Have CD always ON AT C0 Send CD normally the Business Modem sends a CD signal when it connects with another device and drops the CD signal when it disconnects AT C1 ...

Страница 64: ...7 4 CHAPTER 7 CONTROLLING EIA 232 SIGNALING ...

Страница 65: ...ction rates Serial port rates pertain to data transferred between your computer and the Business Modem Connection rates pertain to data transferred between the Business Modem and the device at the other end of a connection Serial Port Rates You set a fixed serial port rate to get the highest possible throughput and the best performance Set a variable rate to allow the Business Modem to match the c...

Страница 66: ...ecify using your communications software for example 38 4 Kbps when the Business Modem connects in ARQ mode If the connection is not under error control the Business Modem behaves as if it was set to B0 and switches its serial port rates to match the connection rate of each call Fixed for ARQ calls and AT B2 To implement this feature first set your software to the desired rate Then send AT B2 W to...

Страница 67: ...ly allow connections with remote devices that are operating at 14 4 Kbps To allow your modem to Set connection rate as Command Negotiate for the highest possible rate Variable AT N0 Connect only if the remote device is operating at the rate you specify See below Fixed AT N1 AT N16 To connect at this rate Command To connect at this rate Command 300 bps AT N1 16 8 Kbps AT N9 1200 bps AT N2 19 2 Kbps...

Страница 68: ...Highest Possible Connect Speed The N command when used in conjunction with the U command allows you to limit the highest possible connect speed If a remote modem attempts to connect to your Business Modem at a speed higher than N your Business Modem will not allow it to connect For a complete list of connect speeds see the table in section N and U Command Values To limit the Use Highest possible c...

Страница 69: ...m does not connect to 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 To limit the Use this command Where x is Lowest possi...

Страница 70: ...nk speeds and their associated indexes Link Speed Index Highest 0 300 1 1200 2 2400 3 4800 4 7200 5 9600 6 12000 7 14400 8 16800 9 19200 10 21600 11 24000 12 26400 13 28800 14 31200 15 33600 16 28000 17 29333 18 30666 19 32000 20 33333 21 34666 22 36000 23 37333 24 38666 25 40000 26 41333 27 42666 28 44000 29 45333 30 ...

Страница 71: ...DTE rate of your Business Modem has been increased to 230 kbps to enhance throughput This command is only supported on Business Modems attached to high speed serial cards 46666 31 48000 32 49333 33 50666 34 52000 35 53333 36 54666 37 56000 38 57333 39 Link Speed Index ...

Страница 72: ...8 8 CHAPTER 8 CONTROLLING DATA RATES ...

Страница 73: ...You should be familiar with these terms before you continue Setting Up Remote Access At the Host Business Modem 1 Prepare to send AT commands by putting your communications software in Terminal Mode Local The device that is directly connected to the computer you are using Remote The device at the other end of a telephone connection Host The Business Modem that will be accessed and controlled by ot...

Страница 74: ...two remote access passwords You can set two passwords to allow different levels of access to each Business Modem Example Sending AT P1 corn will allow a remote user to log in with the password corn The user can view and change the Business Modem s configuration Remote access passwords can be up to eight alphanumeric characters long and are not case sensitive To allow guest users to Use this comman...

Страница 75: ...ice has enabled remote access and is set to auto answer ATS0 1 Know the password if you will need one 2 Call the host device although it doesn t matter which device originates the call 3 After a connection is established do this a Pause 4 seconds b Type 4 tildes c Pause 4 seconds The administrator of the host device can change the remote access character using S Register 42 and the pause duration ...

Страница 76: ...e remainder of the connection When the host accepts the password the following message and prompt will appear on your screen Remote Access granted Remote You may not be prompted for a password If you aren t password security is not active The following prompt appears on your screen after you type the four tildes Remote Access granted query only Remote During a remote access session the maximum num...

Страница 77: ...ness Modem s serial port rate to 9600 bps If you have this access privilege You can use View only Any of the inquiry ATI commands View and Configure Any of the Business Modem commands except those that cannot be used while online for example ATD or ATA You can also use remote configuration commands See the next section for examples To change the host Business Modem s serial port rate to Command To...

Страница 78: ...l not be restored to their previous settings when you send the host AT C1 After you make changes to the host s configuration the remote access prompt changes from Remote to Remote To change the data format to Command No Parity 8 data bits AT F0 Mark parity 7 data bits AT F1 Odd Parity 7 data bits AT F2 Even parity 7 data bits AT F3 For your modem to Command Defer configuration changes to when the ...

Страница 79: ...l C or typing ATO After you ve entered the password you can quit by sending one of these commands Before you disconnect issue the ATI5 command to the remote modem and check its S41 setting Make sure S41 is set for a value of 1 or greater If S41 is set to 0 when you disconnect you will not be able to access the remote modem again To prevent this send ATS41 1 W before you disconnect To end the remot...

Страница 80: ...9 8 CHAPTER 9 ACCESSING AND CONFIGURING THE BUSINESS MODEM REMOTELY ...

Страница 81: ...ounts one administrative account for you and nine accounts for guest users The account profiles are stored in the host Business Modem s nonvolatile random access memory NVRAM There are two forms of Dial Security each will be explained later in this chapter Autopass Password Prompting Local The device that is directly connected to the computer you are using Remote The device at the other end of a t...

Страница 82: ...ty method Enable Dial Security Activate the Dial Security settings 1 Set up an account for yourself Use any of the 40 available accounts numbered 0 39 for your account Use the AT An command to set up user accounts See the figure below for the five fields to concern yourself with The AT An command is automatically written to NVRAM It does not require you to send W WARNING Do not insert spaces betwe...

Страница 83: ...Be sure to remember your administrative password If you enable Dial Security and then forget your administrative password you To make the host Business Modem Command Example Hang up and then dial back a guest device at a specified number Expect a pause of approximately 1 5 minutes before the modem dials back You cannot alter the duration of the pause AT A0 password y y n 1 area code and phone numb...

Страница 84: ...up an account you can modify each field independently If a field is to remain unchanged from its original setting just insert a comma as shown AT A1 Y The command above allows the guest user to supply a dialback number that is different from the one stored in the original account record 4 Enable Local Security WARNING If you do not enable Local Security the Dial Security settings will not be prote...

Страница 85: ... Autopass and Password prompting When using Autopass Prompting When using Password Prompting Both the host and guest devices are made by 3Com and have Dial Security enabled Guest devices don t have to support 3Com Dial Security The connection between the Business Modems or modems is under V 42 error control See Appendix B Alphabetic Command Summary for information about using AT M4 or AT M5 V 42 e...

Страница 86: ...t or power off the Business Modem Dial Security will be disabled If you need a reference when setting these command you can use the ATI10 command See Appendix B Alphabetic Command Summary for more information about the ATI10 command 7 Send ATZ or ATZ to activate the Dial Security settings For your modem to enable Command Autopass Dial Security ATS53 0 1 Dial Security with Password Prompting this a...

Страница 87: ...d Remote Configuration Dial Security accounts may be configured remotely See Configuring Dial Security Remotely at the end of this chapter For your modem to Command Access accounts by disabling local security AT S administrative password View account information once access has been granted Remote users may only use this command during remote access sessions if local access security is disabled AT...

Страница 88: ...istrator asked you to use See Setting Up Dial Security earlier in this chapter for instructions b You need to assign the password as your Autopass password Example Sending AT V PW3 will assign the password as an Autopass password for account 3 c Check to see that you set your Autopass password correctly by using the ATI10 command Your Autopass password appears beside AUTOPASS PASSWORD if you have ...

Страница 89: ...our remote access password Dialing In From the Remote Site 1 From the remote site connect to the host using Dial Security Once a connection is made follow the instructions for beginning a remote access session as described in Chapter 10 Accessing and Configuring the Business Modem Remotely 2 When remote access has been granted use the AT S command to access the Dial Security accounts See Maintaini...

Страница 90: ...NING If you do not use the ATZ command to end a remote access session Dial Security will remain disabled at the host and anyone dialing in to the host for remote access will have access to the ATI10 screen and all Dial Security accounts ...

Страница 91: ...er and one for data received from the phone line Flow control provides a system for stopping and starting transmission depending on how full the buffers are Flow Control s purpose is to prevent overfilling the buffers which may cause data to be lost We recommend that you use hardware flow control If you do depending on your communications software you will also need to enable hardware flow control...

Страница 92: ...uffer is 90 full and then sending special characters in the data stream to stop the flow of data When the buffer drops back to 50 full the Business Modem sends special characters in the data stream to restart the flow of data The problem with software flow control is that the characters used to stop Ctrl Q and start Ctrl S the flow of data can occur naturally in the data flow Enabling software flo...

Страница 93: ...erfere with XON XOFF signaling between the remote computer and remote device see AT I2 AT I1 Force the Business Modem to act on your XON XOFF commands but remove them from the data stream instead of passing them to the remote computer This ensures that the remote computer does not confuse your XON XOFF characters with those from its attached device This is the recommended setting for ARQ mode AT I...

Страница 94: ...te system The error control protocol enables the devices to control the flow of data on the phone link In non ARQ mode a Business Modem set to AT I5 operates as though flow control were disabled AT I0 it does not look for your typed XON XOFF commands However it does look for XON XOFF characters coming in over the phone link When the remote device sends XON XOFF commands the Business Modem either r...

Страница 95: ...d Disable transmit data flow control AT H0 Enable Hardware flow control Requires that your computer and software support Clear to Send CTS at the EIA 232 interface AT H1 Enable Software flow control Requires that your software support XON XOFF signaling AT H2 Use both hardware and software flow control If you are unsure about what your equipment supports select this option AT H3 ...

Страница 96: ...11 6 CHAPTER 11 FLOW CONTROL ...

Страница 97: ...ossible speed when they attempt to connect with another modem 56 Kbps If the remote device is not V 34 capable a connection is made using the highest compatible modulation scheme x2 V 34 V FC V 32 terbo V 32 bis and so on down to as low as Bell 103 or 300 bps Selective Reject The Business Modem supports Selective Reject for analog calls Selective Reject improves performance on noisy lines by reduc...

Страница 98: ...he following conditions for an x2 connection to be made A digital connection at one end ISPs or other online services must have a digital connection to the public switched telephone network PSTN Most major online services have a digital connection to the PSTN Only one digital to analog conversion There can be only one digital to analog conversion in the telephone network between the x2 server mode...

Страница 99: ...establish speeds up to 56K downstream Other Protocols x2 x2 client modems can receive data at speeds up to 56 kbps and send data at V 34 speeds To use x2 the client x2 modem must connect to a server x2 modem If clients attempt to connect to ISPs that do not use x2 the client modem will negotiate the next available modulation For example an x2 client modem calling into an ISP that only supports V 3...

Страница 100: ...r tone which is the prevalent standard in the U S and Canada for connections at 2400 bps and lower At higher speeds the Business Modem also recognizes the ITU answer tones necessary for connecting with V protocol modems and adjusts to the answering device However when answering a call a Business Modem sending out the Bell answer tone B1 won t be recognized by V protocol modems The calling modem in...

Страница 101: ...m in answering older V 32 modems at 9600 bps Use Register S28 to modify the duration of the extra tones used in V 32 negotiations in the rare instance that this may be necessary See Appendix A S Registers Error Control Business Modems can employ error control techniques during data connections High speed data calls are vulnerable to errors unless the data is protected by error control If your Busi...

Страница 102: ...patibility 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 For your modem to Command Have no error control Normal Mode Due to the nature of phone line channels thi...

Страница 103: ...wed before an acknowledgment is required MNP Error Control The Microcom Networking Protocol MNP is supported by the ITU T V 42 Recommendation MNP is based on special protocol frames If the remote device doesn t recognize an MNP Link Request error control isn t possible In HST asymmetrical mode 3Com devices use a proprietary scheme similar to MNP Error Control and Flow Control Flow control of data ...

Страница 104: ... in the CONNECT message if the modem is set to A3 V 42bis versus MNP5 Data Compression Business Modems using V 42bis compression negotiate the following options and report them in the ATI6 display Dictionary size that is the amount of memory available for compression table entries Entries are codes devised for redundant data The data is packed into shorter data units called code words and unpacked...

Страница 105: ... by the remote modem When transferring such files it s best to set the modem to K3 See the information in data compression This allows V 42bis compression to work dynamically with the compressed data but disables MNP5 Getting Maximum Throughput The following guidelines should help you to make the most of the Business Modem s advanced performance features In many instances experimentation and exper...

Страница 106: ...rsion of ZMODEM file transfer protocol For example certain public domain file transfer protocols have the following effects The protocols listed above further reduce throughput when an error control connection is established The accuracy of the data is checked both by the file transfer protocol and the Business Modem To avoid redundancy use the above protocols only for non ARQ connections and only...

Страница 107: ...d also be used for non ARQ connections Leave the Business Modem at its M4 and K1 settings for both error control and data compression YMODEM G is another good choice but never use it unless both the local and remote devices are using error control if YMODEM G detects an error it aborts the transfer Do not use either protocol with software flow control XON XOFF signaling ...

Страница 108: ...12 12 CHAPTER 12 HANDSHAKING ERROR CONTROL DATA COMPRESSION AND THROUGHPUT ...

Страница 109: ... current settings product code and call duration Querying Here is a complete list of ATIn commands Common Inquiry Commands For your modem to display Command Current settings ATI4 NVRAM settings ATI5 Link diagnostics summary ATI6 For your modem to Command Display a four digit product code ATI0 Perform a checksum of the modem s read only memory ROM and display the results This function is used only ...

Страница 110: ... stores information about link operations When the call is ended you can request a diagnostic summary The duration of the last call or the real time is displayed depending on the modem clock setting For calls under data compression the number of characters sent may be less than the number of octets sent due to data compression operations ATI6 Display the product configuration ATI7 Display the Dial...

Страница 111: ...mand options D S Registers S and the octothorpe command set To see the remainder of the screen for any given command press any key For your modem to display Command A partial summary of the basic command set AT A partial summary of the ampersand command set AT A partial summary of S Register functions ATS A partial summary of percent command set AT A summary of the octothorpe command set AT ...

Страница 112: ...13 4 CHAPTER 13 DISPLAYING QUERYING AND HELP SCREENS ...

Страница 113: ...k tests You can use these tests to check the operations of the transmitter and receiver or to locate a problem with a remote device or a telephone line Testing is done by sending the AT Tn command or by setting Register S16 Only one test can be performed at a given time If you send a test command while the modem is in test mode you ll receive an ERROR message All loopback testing conforms to ITU T...

Страница 114: ...nd Summary before testing If the modem is detecting errors and retransmitting the affected data your results will be invalid For your modem to Command End testing AT T0 Enter analog loopback AL mode and send a CONNECT message Data is shown on your screen AT T1 Enter analog loopback mode and send a CONNECT message The Business Modem sends a internal test pattern to the transmitter and loops the pat...

Страница 115: ... end the test by sending ATH or ATZ Be careful though because ATZ resets the modem in addition to ending the test In either case the modem responds with OK If the modem sends an ERROR message you have issued an invalid command 5 Send AT M4 unless you used a reset command ATZ If the Business Modem is in online mode that is still connected to a remote modem and you send AT T1 or AT T8 it drops the c...

Страница 116: ...omputer interface 1 Send AT M0 N3S14 0 0 to the modem prepare for testing This command disables error control fixes the connection rate at 2400 bps and makes the Business Modem return to command mode when you type 2 Send AT T8 to begin the test The Business Modem enters analog loopback AL mode and sends a CONNECT message The MR status light flashes The V Everyhing then sends its internal test patt...

Страница 117: ...Send the Business Modem the escape code to bring it back to Command mode 4 Send AT T3 to the modem to enter Digital Loopback mode 5 Have the remote user type a short message It will be looped back by your Business Modem s transmitter for verification on the remote user s screen You will not see the message or any other data 6 When the remote user has completed the test send the escape code and the...

Страница 118: ...keyboard data sent to the modem by returning it over the phone lines and displaying it on your screen Granting a Digital Loopback Test Request AT T4 Using AT T4 causes the Business Modem to grant a remote device s request for a remote digital loop back test Canceling All Digital Loopback Test Requests T5 Using AT T5 cancels AT T4 and the Business Modem fails to acknowledge remote digital loopback ...

Страница 119: ... remote digital loopback mode and the MR status light flashes 5 Type a short message It will be looped back to your modem by the remote device and to your screen for verification The remote user will not see your data 6 Send the escape code and then AT T0 to end the test Alternatively you can end the test by sending ATH ATZ or ATZ Be careful because ATZ and ATZ reset the Business Modem in addition...

Страница 120: ...oopback request For example older 3Com modems need to be set to S16 8 4 Send AT T7 to the modem The modem enters remote digital loopback mode and the MR status light flashes The Business Modem sends its built in test pattern to the remote device which loops it back to your Business Modem You will not see the data on your screen 5 Send the escape code and then AT T0 to end the test You can also end...

Страница 121: ...ee RDL Testing Using a Built in Test Pattern S16 4 1 Send AT M0 N3S14 0 0 to the modem to prepare for testing This command disables error control fixes the connection rate at 2400 bps and makes the Business Modem return to command mode when you type 2 Send ATS16 1D The modem enters AL mode and sends a CONNECT result code The MR status light flashes 3 Type data to the modem for it to transmit loop ...

Страница 122: ... device to enter remote digital loopback mode The MR status light flashes during this operation 5 Type a short message It will be looped back to your Business Modem by the remote device and to your screen for verification The remote user will not see your data 6 Send the escape code and then ATS16 0 to end the test If you issue an invalid command the Business Modem sends an ERROR message If you se...

Страница 123: ...ttern Ending Testing That Uses the Test Pattern Pressing any character key cancels all tests and hangs up the Business Modem If you used Register S16 be sure to reset Register S16 and return to the error control default Send ATZ or AT M4S16 0 to the modem To use the test pattern during testing with Command S Register 16 AT M0S16 12 The T test The test pattern is used for testing equipment and the ...

Страница 124: ...14 12 CHAPTER 14 TESTING THE CONNECTION ...

Страница 125: ...AT For Windows users make sure that you set the correct COM port and IRQ in your communications software and if applicable in Windows Control Panel Ports For Macintosh users make sure that you set the correct serial port modem port or printer port and that AppleTalk is disabled Make sure that your communications software is in Terminal mode Be sure that your communications software is set to the c...

Страница 126: ...at the Business Modem If so see the chapter about Controlling EIA 232 Signaling Make sure that the phone line from your wall jack connects to JACK port of the Business Modem Make sure the Business Modem is connected to a standard analog phone line and not to a digital system typically found in offices and hotels If the Business Modem responds NO DIAL TONE when you attempt to dial first make sure t...

Страница 127: ...ou finish the call Hear ringing but the Business Modem won t answer Look at the TR LED to make sure that your terminal or computer is sending a DTR signal via the EIA 232 interface Send ATI4 to the Business Modem and check that S0 is set to a value higher than 0 Set F1 and S0 1 then try again The Business Modem acts as though a data link has been established but no call was received Carrier Detect...

Страница 128: ...on may be one of the following Your computer may not support the higher serial port rate If this is the case fix your software rate at 9600 bps If you use memory resident programs TSRs Terminate and Stay Resident programs or disk caching programs they may be interfering Try disabling them before you run your communications software Check that your software and the Business Modem are set for the sa...

Страница 129: ...ng on whether the connection is to be made with a facsimile device or a data device See Chapter 2 Modes of Operation for information on switching between Fax and Data modes Make sure the proper bit rate word length parity and number of Stop bits have been selected Send ATI4 and check to see that your modem is at the correct Bn setting to connect with either an HST modem B1 setting or V modem B0 se...

Страница 130: ...wer serial port rate If your computer doesn t have a 16550 UART set your communications software to use a slower serial port You can also try running the program on a different PC An idiosyncrasy of an off brand PC or an uncommon version of DOS may lock up the SDL program If You Still Have Problems The problems described above are by far the most common ones that users encounter If the suggestions...

Страница 131: ...enty of packing material b Be sure to include your SRO number inside the package along with your name and address Put your return address and your SRO number on the shipping label as well c Ship the package to the following address 3Com Corporation SRO _______________ attn Dock 15 PCD 1800 West Central Mount Prospect IL 60056 3Com will not accept packages sent COD so be sure to send the modem post...

Страница 132: ...15 8 CHAPTER 15 TROUBLESHOOTING ...

Страница 133: ...operating software which are made publicly available from our Web site BBS and ftp site Checking Your Business Modem s Software Version Issuing the ATI7 command produces the following information ati7 3Com OfficeConnect 56K Business Modem Configuration Profile Product type US Canada External Options HST V32bis Terbo V FC V34 Fax Options Class 1 Class 2 0 Clock Freq 20 16Mhz Eprom 256k Ram 32k Supe...

Страница 134: ...ware web page Call the 3Com Bulletin Board Service BBS at 847 262 6000 From the main menu select Files Select area 5 USR Business Modem Download the newest Business Modem file with the extension ZIP Remember to select the proper ZIP file for your Business Modem If you have problems with downloading the current shipping version of the modem s software call 3Com Technical Support at 888 326 6099 Sen...

Страница 135: ... your modem using the XMODEM Checksum or XMODEM CRC protocol Since this is a test the modem s existing software is not erased 4 After you ve completed the test transfer successfully use your communications software to send the XMD file using the XMODEM Checksum or XMODEM CRC protocol See below at x SDL Xmodem file transfer Y es N o T est y Begin Xmodem file transfer now CC SDL Xmodem file transfer...

Страница 136: ... 1 Power your modem off The power switch is in the rear right corner of the back panel 2 While holding in the RESET button between the RS 232 and USB jacks turn the modem back on 3 Start your communications software package Set your port speed to 57 600 bps type AT and press Enter If the Business Modem reports Corrupt Firmware issue the AT X command and repeat the flash process found on the previo...

Страница 137: ... Register as a decimal value between 0 and 255 The modem however understands the decimal value as a collection of binary digits bits How bits are mapped to decimal values Bits can be mapped into decimal values Each bit can be either on 1 or off 0 Eight bits create 256 unique combinations of 1s and 0s Each of the eight bits can be assigned a number corresponding to its position b b b b b b b b 7 6 ...

Страница 138: ...s to bits by finding the largest decimal equivalent that is less than the decimal value Subtract the decimal equivalent and mark the equivalent bit 1 Continue until the decimal value is zero See the example below 113 113 64 49 01 49 32 17 011 17 16 1 0111 1 1 0 01110001 Setting Bit Mapped S Registers You can set bit mapped S Registers using either bits or decimal values While it may be simpler for...

Страница 139: ...e as the one in Using Bits above Default S Register Settings The table below lists all default values for S Register settings S Registers Function NVRAM Default Setting S0 Auto Answer 0 S1 Counts stores rings from incoming calls 0 S2 Escape code character 43 S3 Carriage Return character 13 S4 Line Feed character 10 S5 Backspace character 8 S7 Carrier wait time sec 60 S8 Dial pause sec 2 S9 Carrier...

Страница 140: ...ndshake time 100 ms 8 S29 V 21 handshake time 100 ms 20 S33 Bit mapped functions 0 S34 Bit mapped functions 0 S38 Disconnect wait time sec 0 S41 Allowable remote log in attempts 0 S42 Remote Access ASCII character 126 S43 Remote guard time 200 ms 200 S51 Bit mapped functions 0 S53 Bit mapped functions 0 S54 Bit mapped functions 0 S55 Bit mapped functions 0 S56 Bit mapped functions 0 S69 Bit mapped...

Страница 141: ...er of seconds the Business Modem waits for a dial tone S7 60 Sets the number of seconds the Business Modem waits for a carrier May be set for much longer duration if for example the Business Modem is originating an international connection S8 2 Sets the duration in seconds for the pause option in the Dial command and the pause between command reexecutions and A commands S9 6 Sets the required dura...

Страница 142: ...P Level 3 used for testing Level 2 7 128 Hardware reset works like powering off and then on S14 1 Bit mapped register See the beginning of this appendix for information about setting bit mapped registers Bit Value Result 0 1 Disconnect on escape code S15 0 Bit mapped register See the beginning of this appendix for information about setting bit mapped registers Bit Value Result 0 1 Disable the Busi...

Страница 143: ...r with X and Y modem type File Transfer Protocols without using flow control The 128 byte option allows remote users with slower modems to stop your transmitted data from scrolling off their screens When remote users send your computer an XOFF Ctrl S and you stop transmitting the data in transit doesn t exceed the size of their screen S16 0 Bit mapped register See the beginning of this appendix fo...

Страница 144: ...ts S27 0 Bit mapped register See the beginning of this appendix for information about setting bit mapped registers Bit Value Result 0 1 Enable ITU T V 21 modulation at 300 bps for overseas calls In V 21 mode the Business Modem answers both Bell 103 and V 21 calls but only originates V 21 calls 1 2 Enable unencoded non trelliscoded modulation in V 32 mode this option is part of the ITU T V 32 recom...

Страница 145: ...on to be pushed in order to dial try lengthening the duration of the extra tones Setting S28 to zero eliminates the extra tones resulting in a faster connect time if for example the Business Modem is set to use V 21 modulation 300 bps or V 23 modulation 1200 bps S29 20 Sets the duration in tenths of a second of the V 21 answer tone S34 0 Bit mapped register See the beginning of this appendix for i...

Страница 146: ...l login attempts exceeds the limit set by this register the Business Modem returns online and any further login attempts during the remainder of that connection are refused S42 126 Stores the ASCII decimal code for the remote access escape character The default character is a tilde S43 200 Sets the duration in fiftieths of a second of the guard time for the remote access sequence S44 15 Sets the d...

Страница 147: ...sable 2400 symbol rate 1 2 Disable 2743 symbol rate 2 4 Disable 2800 symbol rate 3 8 Disable 3000 symbol rate 4 16 Disable 3200 symbol rate 5 32 Disable 3429 symbol rate 6 64 Disable Call Indicate CI 7 128 Disable V 8 S55 0 Trellis code bit mapped register used primarily by 3Com Technical Support for debugging purposes Bit Value Result 0 1 Disable 8S 2D mapping 1 2 Disable 16S 4D mapping 2 4 Disab...

Страница 148: ...nables Disables V 90 S69 0 Bit mapped register See the beginning of this appendix for information about setting bit mapped registers Bit Value Result 0 1 Disable Plug and Play signaling 1 2 Disable Multi link Tones S70 0 Bit mapped Register See the beginning of this appendix for information about setting bit mapped registers Bit Value Result 0 1 Enable recognition of Ring A 1 2 Enable recognition ...

Страница 149: ...Wait 1 second before typing any data When you type the modem will either hang up or stay on line depending on how you set S14 Repeat command If you include the repeat command in the Dial string the modem will dial the number and wait 60 seconds for a carrier If the line is busy the modem will pause for 2 seconds and then redial The modem makes a maximum of 10 attempts A Reexecute the last issued c...

Страница 150: ...accepted The maximum number of characters allowed is 36 including the AT prefix punctuation and spaces Optional parameters P Dial using pulses Accepted but ignored T Dial using tones Accepted but ignored Comma Pause for 2 seconds or the time in S Register 8 Accepted but ignored Semicolon Remain in Command mode after dialing Dial the letters that follow W Wait for a second dial tone before continui...

Страница 151: ...ode echo OFF Your typing will not appear on the screen E1 Command mode echo ON Your typing will appear on the screen Command Function Fn Online local echo If ON a modem displays on your screen the data that it is transmitting to another modem F0 Online echo ON Sometimes called half duplex F1 Online echo OFF Sometimes called full duplex Hn Go on or off hook H0 Go on hook hang up H1 Go off hook pick...

Страница 152: ... command and online modes O0 Return online normal O1 Return online and retrain Use O1 if there were errors in a non ARQ data transfer Qn Enable or disable the display of result codes Q0 Display result codes Q1 Suppress result codes quiet Q2 Suppress result codes when answering S Display help screens for the S Registers Sr n Set S Register value r is any S Register n must be a decimal number betwee...

Страница 153: ...RQ result codes A2 In addition to ARQ result codes display HST V 32 V FC or V 34 modulation indicator A3 In addition to ARQ and modulation indicators display an error control indicator LAPM HST MNP or NONE and a data compression type V42bis or MNP5 Bn Set the serial port rate to variable or fixed B0 Variable The serial port rate adapts to match the speed of the connection B1 Fixed The modem always...

Страница 154: ... that are stored permanently in read only memory Appendix C Flow Control Templates lists the settings for each template To load a template into current memory enter AT Fn To write a template to NVRAM enter AT Fn W F0 is always loaded into memory at power on or when the RESET button is pressed F0 Load No Flow Control template settings F1 Load Hardware Flow Control template settings F2 Load Software...

Страница 155: ...tting for ARQ mode I3 Hewlett Packard Host mode Applies only to modems attached to an HP mainframe that uses the ENQ ACK protocol Use in ARQ mode only I4 Hewlett Packard Terminal mode Applies only to modems attached to terminals in an HP system that uses the ENQ ACK protocol Use in ARQ mode only I5 This setting is designed to enable flow control on the phone link when the connection is not under e...

Страница 156: ...ates in Normal mode as though it were set to M0 Nn Sets fixed link speed Nn UN Sets highest and lowest link speeds n 1 Variable rate The modem negotiates with the remote device for the highest possible connection rate depending on the capabilities of the remote device n 1 16 Fixed rate The modem connects only if the remote device is operating at the same rate You can use this feature to filter out...

Страница 157: ...40000 bps n 27 41333 bps n 28 42666 bps n 29 44000 bps n 30 45333 bps n 31 46666 bps n 32 48000 bps n 33 49333 bps n 34 50666 bps n 35 52000 bps n 36 53333 bps n 37 54666 bps n 38 56000 bps n 39 57333 bps Rn Received data RTS hardware flow control R0 Delay Clear to Send CTS response after Request to Send RTS R1 Ignore RTS This setting is required if your computer or terminal or software does not s...

Страница 158: ... without the CTS signal S4 Send the computer DSR at the same time as CD S5 Send DSR normally and follow CTS with CD Tn Test the modem T0 End testing T1 Enter Analog Loopback AL mode Your modem will send a CONNECT message Data is shown on your screen T2 Enter AL mode and send a CONNECT message The Business Modem sends an internal test pattern to the transmitter and loops the pattern back to the rec...

Страница 159: ...6 characters long including any Dial command options Example AT Z2 555 6789 In the following example M0 no error control is inserted before the Dial command AT M0 DS2 This command functions differently when Dial Security is enabled Also do not include modem settings in the Zn string If the call requires a special setting insert it in the command string before the DSn command Zn L Stores the last d...

Страница 160: ... Cn Remote configuration control C0 Defer configuration changes until the call is ended Changes take effect for ensuing connections C1 Cancel configuration changes and restore the original configuration Using C1 will not reverse any changes that you wrote to NVRAM with W or forced with C2 C2 Force configuration changes to take effect immediately Command Function E n Erase security settings E 1 Era...

Страница 161: ...rtain software programs For example T could be used in a security program to identify incoming tone security codes To return the modem to Command mode press any key or drop the computer s or terminal s DTR signal The modem responds OK V PWn Assign the password in account n in your modem s security account as your Autopass password Command Function Command Function Display the help panels for the o...

Страница 162: ...B 14 APPENDIX B ALPHABETIC COMMAND SUMMARY ...

Страница 163: ...during dial through connect Result codes Q0 Enabled Verbal or numeric result codes V1 Verbal result codes Result code subset X7 Extended Includes all codes except VOICE Protocol response codes A3 Full protocol codes Serial port rate select B1 Serial port rate fixed higher than connect rate Carrier Detect C1 Normal operations Data Terminal REady D2 Normal operations Guard tone G0 U S Canada Transmi...

Страница 164: ...dem the AT W string Error control M4 Normal error control Link rate select N0 Variable Pulse dialing type P0 U S Canada Record data hardware flow control R2 Enabled Data Set Ready S0 Always on Remote Digital Loopback RDL T5 Deny RDL Break handling Y1 Clear buffer send immediately Stored telephone number Z0 9 0 Blank Caller ID CID 0 Caller ID disabled Word length 8 Parity 0 None DTE rate Kbps 19 2 ...

Страница 165: ...ult code subset X7 Extended Includes all codes except VOICE Protocol response codes A3 Full protocol codes Serial port rate select B1 Serial port rate fixed higher than connect rate Carrier Detect C1 Normal operations Guard tone G0 U S Canada Transmit data hardware flow control H2 Software flow control Record data software flow control I2 Enabled Analog data compression K1 Enabled Normal lines L0 ...

Страница 166: ...th 8 Parity 0 None DTE rate Kbps 19 2 _ NVRAM Options Setting Description NVRAM Options Setting Description Handshake option B0 ITU T answer sequence Transmitter C1 Enabled Command mode echo E1 Enabled Online local echo F1 Disabled Training tone volume L2 Medium Speaker control M1 ON during dial through connect Result codes Q0 Enabled Verbal or numeric result codes V1 Verbal result codes Result co...

Страница 167: ...a software flow control I0 Disabled Analog data compression K1 Enabled Normal lines L0 Normal lines Error control M4 Normal error control Link rate select N0 Variable Record data hardware flow control R1 Disabled Data Set Ready S0 Always on Remote Digital Loopback RDL T5 Deny RDL Break handling Y1 Clear buffer send immediately Stored telephone number Z0 9 0 Blank Word length 7 Parity 1 Even DTE ra...

Страница 168: ...C 6 APPENDIX C FLOW CONTROL TEMPLATE ...

Страница 169: ...uring the default 2 seconds set in Register S6 7 BUSY Busy signal detect modem hangs up 8 NO ANSWER After waiting 5 seconds for an answer modem hangs up returned instead of NO CARRIER when the option is used 11 RINGING The modem has dialed remote phone line is ringing 12 VOICE Voice answer at remote site modem hangs up 170 RING A Incoming distinctive ring detected 171 RING B Incoming distinctive r...

Страница 170: ...IAL TONE 7 BUSY 8 NO ANSWER 10 CONNECT 2400 11 RINGING 12 VOICE 13 CONNECT 9600 18 CONNECT 4800 20 CONNECT 7200 21 CONNECT 12000 25 CONNECT 14400 43 CONNECT 16800 85 CONNECT 19200 91 CONNECT 21600 99 CONNECT 24000 103 CONNECT 26400 107 CONNECT 28800 151 CONNECT 31200 155 CONNECT 33600 171 RING A 172 RING B 173 RING C 174 RING D Functions Wait for 2nd Dial Tone W Wait for Answer ...

Страница 171: ...Modulation TCM V FC 28 8 26 4 24 21 6 19 2 16 8 14 4 kbps asynchronous TCM V 32 terbo 21 6 19 2 16 8 14 4 12 kbps 9600 7200 bps asynchronous TCM 4800 bps asynchronous Quadrature Amplitude Modulation QAM HST 16 8 14 4 12 kbps 9600 7200 bps asynchronous asymmetrical 450 bps back channel with automatic handshake adjustment to 300 bps TCM and QAM 4800 bps asynchronous asymmetrical 450 bps back channel...

Страница 172: ...s Frequency Shift Keying FSK This modulation Supports This Supports ITU T V 42 LAPM error control 1200 bps and higher MNP Levels 2 3 and 4 error control level 5 data compression 1200 bps and higher HST Asymmetrical mode at 16 8 14 4 12 kbps 9600 7200 4800 bps 450 300 bps back channel ITU T V 42 bis Data compression 1200 bps and higher ITU T V 54 Digital and remote digital loopback testing This Sup...

Страница 173: ...cal speeds in V 32 bis Data format Binary serial defaults to 8 bit word length no parity and 1 stop bit Word Length Parity 1 Bit Stop Bits 7 Even odd mark space 1 7 None 2 8 None 1 Flow Control Buffers Variable sizes Command Buffer 56 characters excluding the AT prefix Carriage Return and spaces Test Options Remote digital loopback digital loopback test pattern and dial test Failed Call Timeout 60...

Страница 174: ...DB 25 to DB 9 Cable DB 9 connectors for PCs should be wired at the computer end of the cable as shown below Minimum Requirements Some computer terminal equipment supports only a few of your modem s EIA 232 signals The minimum required for your modem to operate asynchronously follows DB 25 DB 9 Supports this signal Pin Pin Function 2 3 Transmitted Data 3 2 Received Data 7 5 Signal Ground 20 4 Data ...

Страница 175: ...ow control R2 Pin 4 DB 25 or Pin 7 DB 9 is required For Macintosh Computers If you re connecting your modem to a Macintosh computer we strongly recommend that you purchase a hardware handshaking cable to get the most reliable performance Mac Pin Mac Pin Description Modem Pin Modem Pin Description 1 Output Handshake 4 20 Request to Send and Data Terminal Ready 2 Input Handshake 5 Clear to Send 3 Tr...

Страница 176: ...E 6 APPENDIX E TECHNICAL INFORMATION Serial Ports Macintosh modem These are the signals generated or accepted by your modem s serial port ...

Страница 177: ...8 BS 40 28 72 48 H 104 68 h 09 09 HT 41 29 73 49 I 105 69 I 10 0A LF 42 2A 74 4A J 106 6A j 11 0B VT 43 2B 75 4B K 107 6B k 12 0C FF 44 2C 76 4C L 108 6C l 13 0D CR 45 2D 77 4D M 109 6D m 14 0E SO 46 2E 78 4E N 110 6E n 15 0F SI 47 2F 79 4F O 111 6F o 16 10 DLE 48 30 0 80 50 P 112 70 p 17 11 XON 49 31 1 81 51 Q 113 71 q 18 12 DC2 50 32 2 82 52 R 114 72 r 19 13 XOF F 51 33 3 83 53 S 115 73 s 20 14 ...

Страница 178: ... 19 EM 57 39 9 89 59 Y 121 79 y 26 1A SUB 58 3A 90 5A Z 122 7A z 27 1B ESC 59 3B 91 5B 123 7B 28 1C FS 60 3C 92 5C 124 7C 29 1D GS 61 3D 93 5D 125 7D 30 1E RS 62 3E 94 5E à 126 7E 31 1F US 63 3F 95 5F _ 127 7F DEL Dec Hex Char Dec Hex Char Dec Hex Char Dec Hex Char ...

Страница 179: ... ms FRS n 0 255 Wait for silence 10 ms FTM n 3 24 48 72 73 74 96 121 122 145 146 Transmit data with carrier FRM n 3 24 48 72 73 74 96 121 122 145 146 Receive data with carrier FTH n 3 24 48 72 73 74 96 121 122 145 146 Transmit HDLC data with carrier FRH n 3 24 48 72 73 74 96 121 122 145 146 Receive HDLC data with carrier FNS 0 1 Pass through nonstandard negotiation byte string FCR 0 1 Capability t...

Страница 180: ...clearly contains in a margin at the top or bottom of each transmitted page or on the first page of the transmission the date and time it is sent and an identification of the business other entity or individual sending the message and the telephone number of the sending machine or of such business other entity or individual Telephone facsimile machines manufactured on and after December 20 1992 mus...

Страница 181: ...ax operation ARQ On Is making a data connection using an error control protocol Off Is making a data connection without using an error control protocol AA On Is ready to accept calls Blinking Has detected an incoming call Off Is not ready to accept calls OH On Has control of the line Off Does not have control of the line TD On Is transmitting data Off Is not transmitting data RD Flashing Is sendin...

Страница 182: ...gistration CD On Has detected a carrier from a remote device or carrier detect has been forced on Off Has not detected a carrier RS On Has detected the Ready to Send RTS signal from your computer Off Has not detected the RTS signal from your computer CS On Is sending your computer the Clear to Send CTS signal Off Is not sending your computer the CTS signal This LED Status Means your Business Modem...

Страница 183: ...ge is 0 127 S4 10 Stores the ASCII decimal code for the Line Feed character Valid range is 0 127 S5 8 Stores the ASCII decimal code for the Backspace character A value of 128 255 disables the Backspace key s delete function S6 0 Sets the number of seconds the Business Modem waits for a dial tone S7 60 Sets the number of seconds the Business Modem waits for a carrier May be set for much longer dura...

Страница 184: ...r 1 Using the AT Command Set for instructions about how to set bit mapped registers Bit Value Result 0 1 Reset when DTR drops 1 2 Reverse normal Auto Answer operation On incoming RING enter Originate Mode and look for an answer tone 2 4 Disable 250 ms pause before result code display 3 8 On DTR signal autodial the number stored in NVRAM at position 0 4 16 At power on reset autodial number stored i...

Страница 185: ...er of errors during a call 5 32 Set Backspace key to delete 6 64 Some earlier 2400 bps MNP modems not made by 3Com U S Robotics or Microcom were not fully compatible with the MNP protocol If you have difficulty making a successful 2400 bps MNP connection with a remote MNP modem it may be because of this incompatibility Set S15 to 64 and try again to make the connection 7 128 Custom applications on...

Страница 186: ...ks sent from the Business Modem to the computer or terminal Applies to ARQ mode only S22 17 Stores the ASCII code for the XON character S23 19 Stores the ASCII code for the XOFF character S24 150 Sets the duration in 20 millisecond units between pulsed DSR signals when the Business Modem is set to S2 or S3 The default is 3 seconds S25 5 Sets DTR recognition time in 10 millisecond units S27 0 Bit m...

Страница 187: ...on phase S28 8 Sets the duration in tenths of a second of the extra 3000 600 Hz answer tones sent during V 32 hand shaking This gives V 32 modems additional time to connect in V 32 mode before timing out If there is difficulty answering older manually operated V 32 modems for example modems that require a button to be pushed in order to dial try lengthening the duration of the extra tones Setting ...

Страница 188: ...ts the number of allowable remote access login attempts thus enabling or disabling remote access The default setting of zero allows no remote login attempts thus disabling remote access A value of 1 or greater enables remote access If the number of unsuccessful login attempts exceeds the limit set by this register the Business Modem returns online and any further login attempts during the remainde...

Страница 189: ... Symbol rate bit mapped register used primarily by 3Com Technical Support for debugging purposes Bit Value Result 0 1 Disable 2400 symbol rate 1 2 Disable 2743 symbol rate 2 4 Disable 2800 symbol rate 3 8 Disable 3000 symbol rate 4 16 Disable 3200 symbol rate 5 32 Disable 3429 symbol rate 6 64 Disable V 8 Call Indicate CI 7 128 Disable V 8 Mode S55 0 Trellis code bit mapped register used primarily...

Страница 190: ...le V FC S58 0 Bit mapped register primarily used by 3Com Technical Support for debugging purposes Bit Value Result 0 1 Disable x2 1 2 Reserved 2 4 Reserved 3 8 Reserved 4 16 Reserved 5 32 Disable V 90 6 64 Reserved 7 128 Reserved S70 0 Bit mapped register primarily used by 3Com Technical Support for debugging purposes Bit Value Result 0 1 Enable ring type A 1 2 Enable ring type B 2 4 Enable ring t...

Страница 191: ...f 3Com Replacement products may be new or reconditioned 3Com warrants any replaced or repaired product or part for ninety 90 days from shipment or the remainder of the initial warranty period whichever is longer YEAR 2000 WARRANTY In addition to the Hardware Warranty stated above 3Com warrants that each product sold or licensed to Customer on and after January 1 1998 that is date sensitive will co...

Страница 192: ...to 3Com s Corporate Service Center must be pre authorized by 3Com with a Service Repair Order SRO number marked on the outside of the package and sent prepaid and packaged appropriately for safe shipment and it is recommended that they be insured or sent by a method that provides for tracking of the package The repaired or replaced item will be shipped to Customer at 3Com s expense not later than ...

Страница 193: ...CLUDING NEGLIGENCE FOR INCIDENTAL CONSEQUENTIAL INDIRECT SPECIAL OR PUNITIVE DAMAGES OF ANY KIND OR FOR LOSS OF REVENUE OR PROFITS LOSS OF BUSINESS LOSS OF INFORMATION OR DATA OR OTHER FINANCIAL LOSS ARISING OUT OF OR IN CONNECTION WITH THE SALE INSTALLATION MAINTENANCE USE PERFORMANCE FAILURE OR INTERRUPTION OF ITS PRODUCTS EVEN IF 3COM OR ITS AUTHORIZED RESELLER HAS BEEN ADVISED OF THE POSSIBILI...

Страница 194: ...munications Commission helpful The CIB Interference Handbook and The CIB Telephone Interference Bulletin These documents are available on the Internet through the FCC Compliance and Interference Bureau Home Page at http www fcc gov cib listed under documents Select CIB Interference Handbook or CIB Telephone Interference Bulletin Any changes or modifications not expressly approved by the party resp...

Страница 195: ...he equipment off and on the user is encouraged to try to correct the interference by one or more of the following measures Reorient or relocate the receiving antenna Increase the separation between the equipment and receiver Connect the equipment into an outlet on a circuit different from that to which the receiver is connected Consult the dealer or an experienced radio TV technician for help The ...

Страница 196: ...ice may be extended by means of a certified connector assembly telephone extension cord The customer should be aware that compliance with the above conditions may not prevent degradation of service in some situations Repairs to certified equipment should be made by an authorized Canadian maintenance facility designated by the supplier Any repairs or alterations made by a user to this equipment or ...

Страница 197: ...ceives at the low frequency The transmit receive frequencies are the re verse of the calling modem which is in originate mode application application program A computer program designed to perform a specific function such as a word processor or a spreadsheet ARQ See Automatic Repeat Request ASCII American Standard Code for Information Interchange A 7 bit binary code 0 s 1 s used to represent lette...

Страница 198: ...mission of defective blocks of data See HST MNP and V 42 baud rate The number of discrete signal events per second occurring on a communications channel Although not technically accurate baud rate is commonly used to mean bit rate binary digit bit A 0 or 1 reflecting the use of a binary numbering system only two digits Used because the computer recognizes either of two states OFF or ON Shortened f...

Страница 199: ...nternational Telecommunication Union ITU Telecommunication standards are now covered under Telecommunications Standards Sector TSS ITU T replaces CCITT For example the Bell 212A standard for 1200 bps communication in North America was referred to as CCITT V 22 It is now referred to as ITU T V 22 central office CO The facility to which devices such as telephones fax machines and modems within a spe...

Страница 200: ... In the ARQ protocol implemented in 3Com high speed modems the receiving modem accepts no more data until a defective block is received correctly data communications A type of communications in which computers and terminals are able to exchange data over an electronic medium data compression When the transmitting modem detects redundant units of data it recodes them into shorter units of fewer bit...

Страница 201: ...to the screen for verification digital signals Discrete uniform signals In this manual the term refers to the binary digits 0 and 1 DSR See data set ready DTE See Data Terminal Equipment duplex Indicates a communications channel capable of carrying signals in both directions See Half Duplex Full Duplex echo See local echo EIA Electronic Industries Association which defines electronic standards in ...

Страница 202: ...ached The added information usually includes a frame number block size data error check codes and Start End indicators file transfer protocol FTP A TCP IP application that allows users of an internet to send put and receive get files FTP See file transfer protocol full duplex Signal flow in both directions at the same time In micro computer communications may refer to the suppression of the online...

Страница 203: ...ur computer s expansion bus IP Internet Protocol IPX Novell s Internet Packet Exchange protocol IRQ See interrupt request ISA See Industry Standard Architecture ITU T International Telecommunication Union Telecommunication sector Formerly referred to as CCITT An international organization that defines standards for telegraphic and telephone equipment For example the Bell 212A standard for 1200 bps...

Страница 204: ...manual originate Used when equipment other than the modem does the dialing In such installations the modem does not respond to AT commands but when taken off hook immediately goes into call originate mode MNP See Microcom Networking Protocol modem A device that transmits receives computer data through a communications channel such as radio or telephone lines The Business Modem is a telephone chann...

Страница 205: ...e character even or odd depending on which type of parity is used Plug Play ISA A variation of the standard ISA bus that attempts to automate the troublesome process of resolving the IRQ and COM port conflicts that can arise when new devices are installed in ISA bus computers Point to Point Protocol PPP A protocol used to send data over serial lines PPP provides error checking link control and aut...

Страница 206: ...sal Standard Order Code USOC standard for wiring a single line two wire phone network interface passing tip and ring signals typically from the public switched network ROM See Read Only Memory Serial Line Internet Protocol SLIP A simple protocol that permits sending IP data over a serial line SLIP is being superseded by the Point to Point Protocol PPP serial port A computer port that enables the t...

Страница 207: ...cessor Keyboard entries go directly to the modem whether the entry is a modem command or data to be transmitted over the phone lines Received data is output directly to the screen The more popular communications software products control Terminal mode as well as enable more complex operations including file transmission and saving received files throughput The amount of actual user data transmitte...

Страница 208: ...m communications Among other things V 25 specifies an answer tone different from the Bell answer tone All 3Com modems can be set with the B0 command so that they use the V 25 2100 Hz tone when answering overseas calls Not applicable to the Business Modem V 25 bis An ITU T standard for synchronous communications between the mainframe or host and the modem using the HDLC or character oriented protoc...

Страница 209: ... of ITU T V 42 that defines a specific data compression scheme for use with V 42 error control V Fast Class V FC Proprietary modulation scheme developed by Rockwell International for data communication speeds up to 28 8 Kbps word length The number of bits in a data character without parity start or stop bits XMODEM The first of a family of error control software protocols used to transfer files be...

Страница 210: ...14 GLOSSARY ...

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