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Paradyne KeepInTouch 3766 User Manual

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  • Page 1 You have accessed an older version of a Paradyne product document. Paradyne is no longer a subsidiary of AT&T. Any reference to AT&T Paradyne is amended to read Paradyne Corporation. AREA CODE CHANGE Please note that the area code for Paradyne Corporation in Largo, Florida has changed from 813 to 727.
  • Page 2 3765-A2-GB90-10 Issue 2 May 1995 KeepInTouch PCMCIA Modem Models 3765 and 3766 User’s Guide Member Company Printed on recycled paper...
  • Page 3 Information Important Regulatory COPYRIGHT 1995 AT&T Paradyne Corporation* All Rights Reserved Printed in U.S.A. Notice This publication is protected by federal copyright law. No part of this publication may be copied or distributed, transcribed, stored in a retrieval system, or translated into any human or computer language in any form or by any means, electronic, mechanical, magnetic, manual or otherwise, or disclosed to third parties without the express written permission of AT&T Paradyne Corporation, 8545 126th Ave.

  • Page 4: Important Safety Instructions

    Important Regulatory Information Trademarks Bell is a registered trademark of the Regional Bell Operating Company. COMSPHERE is a registered trademark of AT&T. ETC is a trademark of AT&T. EXTRA! is a registered trademark of Attachmate Corporation. Hayes is a registered trademark of Hayes Microcomputer Products, Inc. KeepInTouch is a trademark of AT&T.

  • Page 5: Government Requirements And Equipment Return

    Important Regulatory Information 5. A rare phenomenon can create a voltage potential between the earth grounds of two or more buildings. If products installed in separate buildings are interconnected, the voltage potential may cause a hazardous condition. Consult a qualified electrical consultant to determine whether or not this phenomenon exists and, if necessary, implement corrective action prior to interconnecting the products.
  • Page 6 Important Regulatory Information 3. The Ringer Equivalence Number (REN) is used to determine the quantity of devices which may be connected to the telephone line. Excessive RENs on the telephone line may result in the devices not ringing in response to an incoming call. In most, but not all areas, the sum of the RENs should not exceed five (5.0).
  • Page 7 To comply with Part 15 FCC Regulations, do not remove or reposition the snap-on ferrite clamp that is attached to the Model 3766 modem’s cellular direct connect cable. To Users of Digital Apparatus in Canada: This Class [B] digital apparatus meets all requirements of the Canadian Interference-Causing Equipment Regulations.
  • Page 8 Important Regulatory Information Notice to Users of the Canadian Public Switched Telephone Network The Canadian Department of Communications label identifies certified equipment. This certification means that the equipment meets certain telecommunications network protective, operational and safety requirements. The Department does not guarantee the equipment will operate to the user’s satisfaction.
  • Page 9 Important Regulatory Information This page intentionally left blank. Issue 2 May 1995...

  • Page 10: Table Of Contents

    Contents Introduction Welcome to the World of Portable, High-Speed Data Communications! KeepInTouch PCMCIA Modem Package Supplied Equipment Additional Equipment You Will Need Where to Find Additional Information Where to Find Technical Support Telephone Numbers Installation Installing Your KeepInTouch PCMCIA Modem Connection to a Telephone Outlet Using the KIT Utilities Installing Fax Software...
  • Page 11 Contents Using Your Modem Viewing, Saving, and Loading Modem Settings View Active and Stored User Profiles Command (&V) Save (Write to Memory) Command (&W) Reload Factory Settings Command (&F) Reload Settings from a User Profile (&Y) Reset Modem and Load User Profile (Z) An Overview of File Transfers and Fax Operation File Transfers Fax Operation...
  • Page 12 Contents Cellular Communications Using Direct Connect Understanding ETC Understanding Automatic Cellular Setup Using Cellular Modem Pools Connecting with Non-ETC Modems Tips for Successful Cellular Operation Overview of Cellular Networks Advanced Modem Concepts Changing Modem Data Rates and Modulations Error Control Data Compression Flow Control Modem-to-Computer Flow Control...
  • Page 13 Figures Introduction Supplied Equipment Installation Modem Installation Using Your Modem Dial Data Network Advanced Modem Concepts Modem-to-Computer Flow Control Various Flow Control Methods Issue 2 May 1995 ....
  • Page 14 Tables AT Command Set and S-Registers AT Command Reference S-Register Reference Troubleshooting Modem Installation Computer Connection Connection Problems while Answering a Call Connection Problems while Placing a Call Online Operation Fax Operation Technical Specifications Technical Specifications Response Codes X Commands’ Effect on CONNECT Response Codes Basic Response Codes Extended Response Codes for...

  • Page 15: Introduction

    Portable, High-Speed Data Communications! Congratulations on your purchase of an AT&T KeepInTouch PCMCIA modem (Models 3765 and 3766). The KeepInTouch PCMCIA modem is a credit card size modem that combines high-speed V.34 data communications with send-and-receive fax capability. The modem fits into any notebook or laptop personal...

  • Page 16: Keepintouch Pcmcia Modem Package

    Introduction KeepInTouch Model 3766 also supports transmission over cellular networks, using the ETC Cellular) protocol. ETC improves data communications over cellular telephone channels. For more information about cellular operation, refer to Appendix D, Cellular Communications . The Hayes AutoSync feature is also supported. For more information on Hayes AutoSync, refer to the Using Hayes AutoSync section on page 3-16.

  • Page 17: Supplied Equipment

    Introduction Supplied Equipment The following hardware and software is included with the modem: One KeepInTouch PCMCIA modem One user’s guide A 2-pin modular telephone cord The following items are optional and may not be packaged with your modem: A KIT Utilities diskette (high-density 3.5 ) containing software for installing, enabling, upgrading, and testing your modem.

  • Page 18: Additional Equipment You Will Need

    For connection to a normal telephone line you need: A telephone outlet (RJ11C in the USA, CA11A in Canada). For connection to a cellular telephone (supported in Model 3766 only) you need: A cellular telephone, A Cellular Direct Connect Cable specific to your type and model of cellular telephone.

  • Page 19: Where To Find Additional Information

    Introduction Where to Find Additional Information Help text files (also called “readme” files) contain supplemental information, such as tutorials and AT command descriptions. They may also contain information that is more recent than what is printed in this user’s guide. Help text files are available through the following sources: KIT Utilities software.

  • Page 20: Installation

    Installation Installing Your KeepInTouch PCMCIA Modem This section describes how to install your KeepInTouch PCMCIA modem. Please take a minute to review these procedures before installing your modem. Use Figure 2-1 and the following steps to install your modem. 1. Locate an unused PCMCIA socket on your PC. Refer to your PC’s user’s guide for more information about the PCMCIA socket.

  • Page 21: Connection To A Telephone Outlet

    If you intend to use regular (land-line) telephone lines, use this procedure. If, however, you want to connect to a cellular telephone (supported in Model 3766 only), refer to Appendix D, Cellular Communications . 1. Plug the modular cord’s 2-pin connector into the modem’s 2-pin rear edge connector.
  • Page 22 Installation CAUTION: If you need to remove the modem from the PCMCIA socket, be sure to unplug the modular cord’s 2-pin connector from the modem before removing the modem from the PC. Refer to your PC’s documentation for instructions on removing the modem from the socket.

  • Page 23: Using The Kit Utilities

    Installation NOTE: If you do not use the KIT Utilities to enable your modem, the COM port and IRQ settings reserved for the modem will be determined by the PCMCIA card enablers on your PC. You need to know these values to set up your communications and fax software applications.

  • Page 24: Installing Fax Software

    Installation To select an option from a KIT Utilities menu, use the up and down arrow keys or press the first letter of the menu item. A brief description of each menu option is displayed as you scroll through the list of options. After you select (highlight) the menu option, press Enter.

  • Page 25: Using Your Modem

    Using Your Modem This chapter highlights some of the basic functions and commands necessary to operate your modem. Whether you consider yourself a novice or an experienced user in data communications, you may want to read through some of the examples to become familiar with your modem’s operation.

  • Page 26: Understanding Your Modem's Operating Modes (Command And Data)

    Using Your Modem Figure 3-1. Dial Data Network Understanding Your Modem’s Operating Modes (Command and Data) Before a modem connects with another modem over a telephone line, it is in Command mode. Command mode is an idle state where you can enter commands to change how the modem functions or to cause the modem to perform an action, such as dialing a telephone number.

  • Page 27: Using At Commands

    Using Your Modem The escape sequence is a series of characters (usually ‘+++’) that you type in to switch from Data mode to online Command mode. Use the escape sequence when you want to enter a command to the modem while it is in Data mode. Think of the escape sequence as a way to get the modem’s attention when it is busy sending or receiving data.

  • Page 28: Response Codes

    Using Your Modem The data character format for the AT command set must be one of the following. It can be set using your communications software: — 8 data bits + no parity + 1 stop bit. — 7 data bits + no parity + 2 stop bits. —...

  • Page 29: Making A Call With Your Modem

    Using Your Modem Making a Call with Your Modem The dial command (D) is used to place a call. When the modem receives this command, it goes off-hook and connects the modem to the phone line so that a call can be made (similar to picking up a telephone’s handset), and dials the telephone number specified in the command string.
  • Page 30 Using Your Modem W – Wait for Dial Tone. The modem waits for a specified time before expecting a second dial tone, then begins processing the dial string. For example, if you must dial a 9 to reach an outside telephone line, the W modifier delays the modem from dialing until it receives a second dial tone for the outside line.

  • Page 31: Examples Of Dial Command Strings

    Using Your Modem Examples of Dial Command Strings Local Call using Tone Dialing In this example, D is the dial command, T is the Tone dialing modifier, and 555-1234 is the telephone number. TYPE: ATDT 5551234 PRESS: Enter Calling through a Private Branch Exchange (PBX) In this example, Tone dialing is selected, a 9 is dialed to pass through the PBX (to get an “outside”...
  • Page 32 Using Your Modem If you would like to know more about the function of the dial command, refer to the following commands in Chapter 4: P (Pulse Dial), T (Tone Dial), &Z (Store Telephone Number), S6 (Blind Dial Pause Time), S7 (No Answer Time-out), and S8 (Pause Time Dial Modifier).

  • Page 33: Between Data Mode And Online Command Mode

    Using Your Modem Manually Answering a Call The best way to answer a call is to set the Auto-Answer Ring Number register (S0) to 1 or more rings. To enable this feature, set the value of S0 to 1 or more rings. If S0 = 0 (which is the setting from the factory), use the A command to manually answer incoming calls, as follows: TYPE:...

  • Page 34: G Viewing, Saving, And Loading Modem Settings

    Using Your Modem NOTE: The escape sequence character (+) and the escape guard time are determined by the S2 and S12 registers, respectively. To change these values, refer to the descriptions of these S-Registers in Chapter 4. For more information on Command and Data modes, see page 3-2.

  • Page 35: View Active And Stored User Profiles Command (&V)

    Using Your Modem View Active and Stored User Profiles Command (&V) The &V command displays a summary of the modem’s Active Profile, either User Profile 0 or User Profile 1, and any telephone numbers saved by the &Z command. To use the &V command: TYPE: AT&V n where n is...

  • Page 36: Reload Factory Settings Command (&F)

    Using Your Modem Reload Factory Settings Command (&F) The modem ships from the factory ready to operate with your computer and transfer data over a normal telephone line. If you have changed several configuration options that no longer apply to what you want to do, you can reload the original factory template with the &F command.

  • Page 37: Reload Settings From A User Profile (&Y)

    Using Your Modem Reload Settings from a User Profile (&Y) Use the &Y command to select whether the contents of either User Profile 0 or User Profile 1 are loaded into Active memory each time the modem turns on or when a reset command (Z) is issued.

  • Page 38: G An Overview Of File Transfers And Fax Operation

    Using Your Modem An Overview of File Transfers and Fax Operation The purpose of this section is to make you aware of the basic concepts involved when using your modem to transfer and receive files and fax messages. For information on how to use your communication or fax software, refer to the documentation provided with your software package.

  • Page 39: Fax Operation

    Using Your Modem A file transfer protocol sets the ground rules that your modem and the remote system use to move files back and forth. Check your communications software manual for descriptions of the various protocols it supports; the software program usually walks you through the download/upload process.
  • Page 40 The &F command is described pages 3-12 and 4-12. Using Cellular Channels KeepInTouch Model 3766 modems can be connected to selected cellular telephones. For more information on cellular operation, refer to Appendix D, Cellular Communications . 3-16...
  • Page 41 AT Command Set and S Registers AT Commands and S-Registers This chapter provides a list of all AT commands and S-Registers supported by the KeepInTouch PCMCIA modem. In general, AT commands are responsible for instructing the modem to do a task, such as dialing, hanging-up, loading factory default settings, etc.

  • Page 42: At Command Set And S-Registers

    AT Command Set and S-Registers Table 4-1. AT Command Reference (1 of 18) Command Description ESCAPE SEQUENCE The escape sequence allows the modem to exit Data mode and enter online Command mode. For more information on using this command, see page 3-9. REPEAT LAST COMMAND This command re-executes the last ‘AT’...
  • Page 43 AT Command Set and S-Registers Table 4-1. AT Command Reference (2 of 18) Command Description DIAL This command causes the modem to immediately go off-hook and dial a telephone number with corresponding dial modifiers. Dial modifiers are parameters that define how the modem should dial the telephone number.
  • Page 44 AT Command Set and S-Registers Table 4-1. AT Command Reference (3 of 18) Command Description COMMAND CHARACTER ECHO This command controls whether or not the characters you enter from your computer’s keyboard are echoed back to your monitor when the modem is in Command mode. Disables echo.
  • Page 45 AT Command Set and S-Registers Table 4-1. AT Command Reference (4 of 18) Command Description RESPONSE CODES This command determines whether or not the modem will send response codes to the computer. Enables response codes. Disables response codes. S n = x CHANGE S-REGISTER This command is used to change the value of an S-Register.
  • Page 46 AT Command Set and S-Registers Table 4-1. AT Command Reference (5 of 18) Command Description EXTENDED RESPONSE CODES, DIAL TONE DETECT, BUSY TONE DETECT This command controls three different configuration options. Extended Response Codes allow additional information to be displayed in response code messages. When disabled, only Basic response codes (OK, CONNECT, RING, NO CARRIER, and ERROR) are displayed.
  • Page 47 AT Command Set and S-Registers Table 4-1. AT Command Reference (6 of 18) Command Description Extended Response Codes (continued) X0 Disabled (CONNECT) X1 Enabled (CONNECT line rate) X2 Enabled (CONNECT line rate) X3 Enabled (CONNECT line rate) X4 Enabled (CONNECT line rate) X5 Enabled (CONNECT line rate/REL) X6 Enabled...
  • Page 48 AT Command Set and S-Registers Table 4-1. AT Command Reference (7 of 18) Command Description \A n MAXIMUM FRAME SIZE This command determines the maximum frame (or block) size used for V.42 or MNP error control operation. If the telephone connection is poor, a smaller frame size may improve the modem’s performance.
  • Page 49 AT Command Set and S-Registers Table 4-1. AT Command Reference (8 of 18) Command Description \G n MODEM-TO-MODEM FLOW CONTROL In normal mode (set by the \N0 command or after fallback), this command enables modem-to-modem flow control using XOFF and XON characters to stop and start transmission between modems, respectively.
  • Page 50 AT Command Set and S-Registers Table 4-1. AT Command Reference (9 of 18) Command Description \N n SET ERROR CONTROL MODE This command determines the type of connection attempted by the modem. If this command is entered while in online Command mode, the changes will not take effect until the next time a connection is established.
  • Page 51 AT Command Set and S-Registers Table 4-1. AT Command Reference (10 of 18) Command Description \Q n SET SERIAL PORT FLOW CONTROL This command specifies the DTE-to-modem flow control. Software flow control uses the XOFF and XON characters to stop and start data transmission, respectively, both to and from the DTE.
  • Page 52 AT Command Set and S-Registers Table 4-1. AT Command Reference (11 of 18) Command Description &C n CD CONTROL This command controls the CD (Carrier Detect) signal. &C0 State of carrier from the remote modem is ignored. CD is always on. (Also known as Forced On.) &C1 State of carrier from the remote modem is tracked.
  • Page 53 AT Command Set and S-Registers Table 4-1. AT Command Reference (12 of 18) Command Description &G n GUARD TONE This command determines whether guard tones are sent out while the modem is connected to a remote modem. Guard tones are not used in North America but are mandatory in some countries outside of North America.
  • Page 54 AT Command Set and S-Registers Table 4-1. AT Command Reference (13 of 18) Command Description &P n DIAL PULSE RATIO This command determines the make/break (off-hook/on-hook) ratio during pulse dialing. &P0 Make = 39%, Break = 61% (for use in the United States). &P1 Make = 33%, Break = 67% (not recommended for use in the United States).
  • Page 55 AT Command Set and S-Registers Table 4-1. AT Command Reference (14 of 18) Command Description &T n &T3 Local Digital Loopback test. This test causes your modem to return any data it receives back to the (continued) remote modem. The remote modem monitors the returned data for errors.
  • Page 56 AT Command Set and S-Registers Table 4-1. AT Command Reference (15 of 18) Command Description &V n VIEW ACTIVE AND STORED USER PROFILES This command displays a summary of the command and S-Register information in the Active Profile (currently being used) and in one of the two stored User Profiles.
  • Page 57 AT Command Set and S-Registers Table 4-1. AT Command Reference (16 of 18) Command Description &Z n = x STORE TELEPHONE NUMBER This command stores telephone number x into directory n . n = 0–3 (the directory location in which to store the number).
  • Page 58 AT Command Set and S-Registers Table 4-1. AT Command Reference (17 of 18) Command Description %B n MAXIMUM DATA RATE AND MODULATION This command sets the modulation, and the maximum data rate, at which the modem may establish a connection. The modem may use data rates lower than the values set with this command if Autorating (S76) and Automoding (S78) are enabled.
  • Page 59 For information on locating help text files, see page 1-5. This command is not reset to its factory setting when an &F is entered. NOTE: This command is supported only in Model 3766. Cellular connections are not supported in Model 3765. Issue 2 May 1995...

  • Page 60: S-Register Reference

    AT Command Set and S-Registers Table 4-2. S-Register Reference (1 of 5) S-Register Description S0= n AUTO-ANSWER RING NUMBER This S-Register determines the number of rings the modem counts before automatically answering a call. A ring count of 0 disables the auto answer feature. n = 0–255.
  • Page 61 AT Command Set and S-Registers Table 4-2. S-Register Reference (2 of 5) S-Register Description S6= n BLIND DIAL PAUSE TIME This S-Register determines how long (in seconds) the modem waits, after going off-hook, before dialing a telephone number when Dial Tone Detect has been disabled (X0, X1, or X3).
  • Page 62 AT Command Set and S-Registers Table 4-2. S-Register Reference (3 of 5) S-Register Description S11= n DTMF TONE TIMER This S-Register controls the length of the DTMF (touch tone) on time. This register is not used for pulse dialing. n = 50–255 milliseconds. Factory setting is 95ms.
  • Page 63 S-Register S78, and Appendix E, Advanced Modem Concepts. 0 = Enables autorating. 1 = Disable autorating. 2 = Enables autorating, starting at 4800 bps. (Available in Model 3766 only.) 3 = Enables autorating, starting at 9600 bps. (Available in Model 3766 only.) S78= n AUTOMODE CONTROL This S-Register determines whether or not your modem uses automoding.
  • Page 64 AT Command Set and S-Registers Table 4-2. S-Register Reference (5 of 5) S-Register Description CONSTANT DTE SPEED If disabled , the DTE speed is independent of the connection speed, allowing much greater throughput when using error control and data compression. If enabled , the serial-port speed (DTE) automatically changes to match the modem-connection (DCE) speed.

  • Page 65: Troubleshooting

    Troubleshooting This appendix points out basic problems that can occur when using a modem. It begins with simple actions and progresses to more detailed reasons as to why your modem may not work properly. Your modem may have come with a KIT Utilities diskette. If you have this diskette, there is a diagnostics program that can assist you in troubleshooting problems with your modem.

  • Page 66: Modem Installation

    Troubleshooting If the Diagnostics option detects that the firmware on your modem has been corrupted, you can download new firmware files from a BBS and then use the Upgrade option of the KIT Utilities to load the new firmware into your modem. Review the section, Where to Find Additional Information , which begins on page 1-5.
  • Page 67 Troubleshooting Use Table A-2 to isolate problems with the connection between your modem and computer. This table focuses on the modem not accepting AT commands from the computer. Table A-2. Computer Connection Symptom Action Modem does not Make sure that the communications software has accept or echo back the correct COM port selected.

  • Page 68: Connection Problems While Answering

    Troubleshooting Table A-3 provides some solutions to problems that can occur when your modem tries to answer a call. Table A-3. Connection Problems while Answering a Call Symptom Action Modem does not go Make sure the modem and PCMCIA socket are off-hook and answer configured for modem operation.

  • Page 69: Computer Connection

    Troubleshooting Table A-4 provides some solutions to problems that can occur when your modem tries to place a call. Table A-4. Connection Problems while Placing a Call (1 of 3) Symptom Action Modem does not go Make sure the modem and PCMCIA socket are off-hook and begin configured for modem operation.
  • Page 70 Troubleshooting Table A-4. Connection Problems while Placing a Call (2 of 3) Symptom Action Intermittent If you are using an operating mode that uses flow disconnects, high control (any \N setting except \N1), make sure error rates, or both modems are using the same type of flow excessive control.

  • Page 71: Call

    Troubleshooting Table A-4. Connection Problems while Placing a Call (3 of 3) Symptom Action Modem establishes You may have a poor telephone line connection. and disconnects a Try dialing again. call The remote modem may have encountered an error control disconnect, where the modem is configured to establish a call using error correction.

  • Page 72: Fax Operation

    Troubleshooting If the modems are having trouble passing data after connecting, check the recommendations and solutions to this problem in Table A-5. Table A-5. Online Operation Symptom Action Data is scrambled Use your communications software to verify that the character format (data bits, parity, and stop bits) is set to the same value in both modems.

  • Page 73: Technical Specifications

    Technical Specifications Table B-1 lists technical specifications for PCMCIA modem. Table B-1. Technical Specifications (1 of 2) Specifications APPROVALS FCC Part 15 FCC Part 68 DOC CS-03 COMPATIBILITY Dial-Line Modulations Fax Modulations ENVIRONMENT Operating Temperature Relative Humidity Shock and Vibration Storage Temperature the KeepInTouch Description...

  • Page 74: Technical Specifications

    16,800, 14,400, 12,000, 9600, 7200, 4800, 2400, 1200, or 300 bps. 115,200, 57,600, 38,400, 19,200, 14,400, 12,000, 9600, 7200, 4800, 2400, 1200, or 300 bps. CCITT V.42 and MNP 2–4 CCITT V.42bis and MNP 5 Enhanced Throughput Cellular (ETC). (Model 3766 only.)

  • Page 75: Response Codes

    Response Codes Response codes are messages sent from the modem which are displayed on your PC’s monitor. These messages are the modem’s response to commands you have sent to the modem. They can inform you of the status of a call (RING, NO ANSWER), or whether or not a command is valid (OK, ERROR), or whether or not the modem has connected using error control (CONNECT 14400/REL).
  • Page 76 Response Codes Table C-1 describes the X command’s effect on the type of information included in the CONNECT response code when when a connection is established. Table C-1. X Commands’ Effect on CONNECT Response Codes Modem-to- Modem (DCE) Line Rate X1–X4 For example, if you have X1 set, you may see a response message such as “CONNECT 57600”.

  • Page 77: Extended Response Codes For Failed Connections

    Response Codes Table C-2 describes the Basic response codes supported by PCMCIA modem (when Q0 and X0 are set). KeepInTouch Table C-2. Basic Response Codes Number Word Format Format (V0) (V1) CONNECT RING NO CARRIER ERROR Tables C-3 and C-4 list the Extended response codes. Table C-3 describes the Extended response codes that may appear when a connection fails.

  • Page 78: Extended Response Codes For Successful Connections

    Response Codes Table C-4. Extended Response Codes for Successful Connections Number Word Format Format (V0) (V1) CONNECT 1200 CONNECT 2400 CONNECT 4800 CONNECT 9600 CONNECT 14400 CONNECT 19200 CONNECT 7200 CONNECT 12000 CONNECT 16800 CONNECT 1200/75 Connection using V.23. Receives at CONNECT 75/1200 Connection using V.23.

  • Page 79: Cellular Communications

    NOTE: Cellular operations are supported in Model 3766 only. Model 3765 modems do not support cellular connections. For information on the models of cellular telephones which can be directly connected to your modem, and information on how to order a Cellular Direct Connect cable, refer to the help text file “cellv34.txt.”...
  • Page 80 Cellular Communications To connect the modem to a cellular telephone with a Cellular Direct Connect cable, first install and enable the modem in your PC, as described in Chapter 2, Installation . Then use the following steps and Figure 2-1 on page 2-2 to connect the modem directly to your cellular telephone: WARNING: Be sure to use an AT&T approved Cellular Direct Connect...

  • Page 81: Cellular Setup

    Cellular Communications Understanding ETC To ensure successful data transfer over a cellular channel, your modem supports the ETC (Enhanced Throughput Cellular) protocol, which increases modem performance and reliability when transferring data over cellular telephone channels. The ETC protocol provides a number of enhancements to both the V.42 error control protocol and the V.32bis modem protocol.

  • Page 82: Configuration Options Set By Automatic

    Cellular Communications Table D-1. Configuration Options Set by Automatic Cellular Setup Configuration Automatic Cellular Setting Option Maximum Frame Size 32 characters/frame Maximum Data Rate 14,400 bps, V.32bis Error Control Mode V.42 (4800 bps or higher), V.42 or MNP (2400 bps or lower) No Carrier Disconnect 10 seconds No Answer Timeout...
  • Page 83 Cellular Communications Connecting with Non-ETC Modems For best operation, it is recommended that the land-line modem also support the ETC protocol. When this is not possible, adequate operation can usually be obtained. The following describes changes to both the cellular site and land-line modems that can improve modem performance.
  • Page 84 Cellular Communications Tips for Successful Cellular Operation The following section lists several issues to be aware of when using cellular channels for data communications: When using a new software package, computer, or modem for the first time, always try a land-line connection first.
  • Page 85 Cellular Communications When using a transportable cellular telephone (a 3-watt telephone), better operation may be obtained by using an external antenna. Performance when stationary is usually better than when moving. If you encounter problems, stop the vehicle and place the call from a stationary position Z modem protocol is recommended for file transfers.
  • Page 86 Cellular Communications The following is a brief list of some of the interferences your signal is subject to when using cellular channels: Man-made and natural structures, such as buildings, tunnels, trees, hills, and valleys can block your signal. Your proximity to the cell’s transmission tower can affect your signal’s strength.

  • Page 87: Advanced Modem Concepts

    Advanced Modem Concepts Changing Modem Data Rates and Modulations Your modem is capable of communicating with other modems at several different data rates, from 300 bits per second (bps) up to 28,800 bps. When a connection with another modem is first being established, there are certain negotiations that take place between the two modems.
  • Page 88 Advanced Modem Concepts The %B command, S-Register S76 (Autorate), and S78 (Automode) work together: If Automoding and Autorating are both off, a connection can only be made if the remote modem agrees to use the data rate and modulation set by %B. If Automoding is on, modulations and data rates lower than the maximums set by %B can be used (even if Autorating is off).

  • Page 89: Error Control

    Advanced Modem Concepts Error Control Error control guarantees that data sent and received between your modem and the remote modem arrives with 100% accuracy. Your modem uses the CCITT standard V.42 and MNP error control protocols. These protocols make sure that errors are eliminated —...

  • Page 90: Modem-To-Computer Flow Control

    Advanced Modem Concepts The format for the command that controls data compression is: TYPE: AT%C n where n is 0 for off and 1 for on. PRESS: Enter Flow Control Flow control is a method of stopping and starting data flow between two devices.

  • Page 91: Various Flow Control Methods

    Advanced Modem Concepts Figure E-1. Modem-to-Computer Flow Control In turn, Modem B can use V.42 or MNP flow control techniques (if using error control), or it can send an XOFF to Modem C to stop data flow (if using modem-to-modem flow control). This is illustrated in link B—C of computer-to-modem flow control in Figure E-2.

  • Page 92: Computer-To-Computer Flow Control

    Advanced Modem Concepts If Modem C’s buffer begins to fill because of data sent from Computer D, Modem C stops data flow either by issuing an XOFF or by lowering its CTS signal to Computer D. This is illustrated in link C—D of computer-to-modem flow control in Figure E-2.
  • Page 93 Glossary Active Profile A nonvolatile configuration area containing the most recently saved configuration options. Any changes made to configuration options can be saved by issuing a &W command. analog signal A type of signal used to transmit data over telephone lines. Answer mode The modem is in a state where it is ready to receive an incoming call.
  • Page 94 Glossary Bell 103J An AT&T Bell standard for 300 bps data transmission. Bell 212A An AT&T Bell standard for 1200 bps data transmission. Bits per second. Indicates the speed at which data is transmitted between devices. buffer A storage area used to compensate for differences in data flow rate when transmitting data from one device to another.
  • Page 95 Glossary configuration option Modem software that sets specific operating parameters for the modem. Sometimes referred to as straps. Clear to Send. A signal sent to the computer which indicates that the modem is ready for the computer to transmit data. data compression The elimination of empty fields, redundancies, and gaps in order to reduce storage capacity needs and the amount of data to be...
  • Page 96 Glossary digital signal A signal used to transfer data between a locally attached computer and modem. download A file transfer in which a file is received from another computer. Data Set Ready. A signal from the modem to the computer that indicates the modem is turned on and connected to the computer.
  • Page 97 Glossary factory defaults A predetermined set of configuration options containing the optimum settings for operation on asynchronous dial networks. fax software Software installed on a computer that allows a modem to send and receive facsimiles from another fax modem or fax machine. flow control A process in which devices stop and start the flow of data in a network to avoid losing data.
  • Page 98 Glossary LAPM Link Access Protocol for Modems, used in V.42 and V.42bis modes. loopback test Any test that verifies the integrity of a device by sending data from one device to another, and then checking the received data for errors. Various loopback tests can be used to isolate a problem to the computer, modem, or telephone line.
  • Page 99 Glossary nonvolatile This term describes memory which does not lose its contents when the device is powered down. Modem options are saved in nonvolatile memory when you use the &W command. off-hook A telephone or modem is being used. on-hook A telephone or modem is not being used.
  • Page 100 Glossary PSTN Public Switched Telephone Network. This term is used to refer to a normal land-line telephone network (as opposed to a cellular telephone network). pulse dialing One of two dialing methods, in which telephone numbers are sent as pulses (brief changes in voltage or current intensity) across the telephone line.
  • Page 101 Glossary serial port The serial port is the connection between the PC and its attached modem. S-Registers Registers that contain information affecting the modem parameters. All S-Registers must be preceded by the AT prefix. synchronous transmission Data transmission that is synchronized by timing signals. Characters are sent at a fixed rate.
  • Page 102 Glossary upload A file transfer in which you send a file to another computer. User Profile 0 A user-defined configuration area containing customized configuration options for a specific application. User Profile 1 A user-defined configuration area containing customized configuration options for a specific application. Volatile This term describes memory which loses its contents when the device is powered down.
  • Page 103 Glossary V.32 A standard for modems operating full-duplex with asynchronous or synchronous data at 9600 or 4800 bps on dial or leased telephone lines. V.32bis A standard for modems operating full-duplex with asynchronous or synchronous data over dial or leased telephone lines at 14,400, 12,000, 9600, 7200, or 4800 bps.
  • Page 104 Index AutoSync. See Hayes AutoSync Active User Profile, 3-10 AT Commands. guidelines for use, 3-3 +++ (escape sequence), 3-9, A/ (repeat last command), 4-2 A (answer), 4-2 B (CCITT/Bell Mode), 4-2, E-2 C (automatic cellular setup), D-3 D (dial), 3-5, 4-3 E (command character echo), H (hook), 3-8, 4-4 I (modem identification), 4-4...
  • Page 105 Index backspace character (S5), 4-20 blind dial pause time (S6), 4-21 blind dialing, 4-6 break signal control (\K), 4-9 bulletin board system, 1-5 busy tone detection (X), 4-6, C-3 carriage return character (S3), 4-20 CD control (&C), 4-12 Cellular Direct Connect Cable, 1-4, D-1 cellular operation Automatic Cellular Setup, D-3...
  • Page 106 Index factory settings, 3-12, 4-1 fax, 1-1, 1-4, 2-5, 3-14, A-8 file transfers, 3-14 firmware revision display (I1), 4-4 flash hook dial modifier (!), 4-3 flow control, A-8, E-4 computer-to-modem, 4-11 modem-to-modem (\G), 4-9 XON/XOFF passthrough (\X), 4-11 frame size (\A), 4-8 guard tone selection (&G), 4-13 hanging up (H), 4-4 Hayes AutoSync, 1-2, 3-16...
  • Page 107 Index pause time dial modifier (S8), 4-21 PCMCIA, 1-1 pulse dialing (P), 4-4 readme files. See help text files reliable mode (\N2), 4-10 remote digital loopback test, 4-15 resetting and loading a User profile (Z), 4-7 response codes, 3-4, C-1 basic vs.
  • Page 108 Index loading on power-up, 4-16 V.17 fax. See fax V.42/MNP 5 data compression (%C), 4-19 W dial modifier – wait for dial tone, XON/XOFF passthrough flow control (\X), 4-11 ZMODEM, 3-14 Issue 2 May 1995 IN-5...

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