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14.4Kbps MODEM Using the 14.4Kbps Modem Documentation File. This file provides installation and operating instructions for the 14.4Kbps MODEM, including internal and external versions. The information assumes the user has basic computer skills but will attempt to explain modem operations and command structure. All sections should be read carefully before beginning any installation procedures. In addition to following the instructions provided here, you will also need to consult the documentation supplied with your communications software. IMPORTANT NOTICE FCC Requirements The Federal Communications Commission (FCC) restricts the way you can use modems. Read the FCC compliance statement found in Appendix C of this file. Telephone Company Requirements Some telephone companies require notification when any electronic communications equipment is connected to the telephone lines. Contact the phone company before connecting your modem to the telephone line and provide them with the following information: * The telephone number of the line that you are attaching the modem. * The modem's FCC registration number and ringer equivalence number. These numbers are printed on the FCC label which appears on the main chip in the center of the internal modem board, or on the underside of the external modem. You can connect the modem to various types of telephone jacks. The acceptable phone jack types are RJ-11, RJ-12, RJ-13, RJ-41S, and RJ-45S. Most homes and businesses use one of these jacks. If your phone system does not have a modular jack, you can purchase an adapter to convert your jack into an RJ-11C jack. Adapters may be purchased from any local phone or electronics store. *************************************************************** QUICKSTART If you are familiar with personal computers and modems, you may follow the accompanying diagram to quickly install either the INTERNAL or EXTERNAL version of the 14.4Kbps modem in your system. Make all necessary connections as shown in those diagrams. To verify line connection, lift your telephone receiver to check for a dial tone. If you are using a dedicated line, plug the line into any phone. After hearing the tone, power on your computer, load your communication software, and put the program into command mode. If you do not hear a dial tone, see Section Eight: Troubleshooting. **************************************************************** Introduction The 14.4Kbps modem (internal or external version) combines high-speed data, modem, and fax capability on a single device. It features V.32bis, which provides high-speed data transmission plus support for V.42bis (error correction) and MNP5 (data compression). Features * Data transmission rates of 14.4K, 12K, 9600, 7200, 4800, 2400, 1200, or 300bps. * 100% data compatibility with the Hayes 'AT' command set. * Programmable speaker volume control * Automatic voice and data switching. * Auto-speed sensing. * V.32bis, V.42bis, and MNP5 are supported as well as V.42 and MNP 2-4 error correction, offering throughput speed of 57,600 bps. * Group III send and receive fax capability with support for Class 1 and Class 2 fax commands. * Supports 100 x 196 high resolution and 100 x 98 low resolution. * Supports high-level data-link control framing. * Communication ports selectable as COM1, 2, 3, or 4 using interrupts 3, 4, 5, or 7 (INTERNAL ONLY). To get started, go to: * SECTION ONE IF YOU HAVE THE INTERNAL MODEL. * SECTION TWO IF YOU HAVE THE EXTERNAL MODEL. NOTE ON TERMINOLOGY: When you encounter the following acronyms, keep in mind their meanings: DTE. Data Terminal Equipment. The computer or terminal, either local (yours), or the remote (the one you're communicating with). (computer-to-modem link) DCE. Data Communications Equipment. The local and/or remote modem. (modem-to-modem link) DTR. Data Terminal Ready. Computer provides this signal to the attached modem indicating that it is ready to receive data. Suggested Additional Technical Resource: * The Complete Modem Reference, Gilbert Held, John Wiley & Sons, Inc. Installation Hints Your MODEM has been initialized during factory final test for optimum performance with included fax communications software. The following initialization (INIT) string has been found to work with many popular communication packages: AT&F~~~E1V1X4&C1&D2%E1 Some bulletin boards and information services have problems with data compression. If so, add %C0 (0=zero) to the init string. If you experience difficulties sending or receiving faxes, please disable all TSR (terminate and stay resident) programs. A TSR program is a program which remains in memory after it loads. The easiest way to test the fax send/receive function by disabling the TSRs is to boot your computer with a plain DOS boot diskette (no config.sys or autoexec.bat files on the boot diskette). Change to the directory containing your fax software. Load the software and send a fax. If you experience a data connection difficulty with a U.S. Robotics HST Dual Standard Modem on a BBS, the following should allow you to connect. First, set the modem software to a DTE speed of 9600. Then enter: ATN0 Follows the S37 Register ATS37=9 Forces modem to connect at 9600 bps. HOW THIS FILE IS ORGANIZED Quick Start. If you are familiar with modem operations, this abbreviated procedure provides a short cut for installing either an internal or external version of the 14.4Kbps modem. Otherwise, read Section One before continuing. Section One and Two : Getting Started. These sections provide communication settings (internal only), physical installation instructions (including how to connect the phone line), and procedures for testing the connection). Refer to your Communications Software Manual for fax command operation. Section Three: Data Modem Operation. A discussion of data modem functions and AT commands and syntax. Also included are definitions of the modem's S-Registers. These registers are used to change certain operating characteristics and obtain information about the modem's state of readiness, as well as test operation. Section Four: MNP Operation. This section explains how to make use of the Microcom Networking Protocols. MNP is an error correction protocol developed by Microcom and is widely supported by modem manufacturers. Section Five: Error Correction: V.42/V.42bis. V.42 and V.42bis are CCITT (Consultative Committee on International Telegraph and Telephone) standards for error correction and data compression, respectively. This section describes the AT commands and S-registers which activate and control these functions. Section Six: V.32bis/V.32 Operation: A brief discussion of these CCITT standards for high-speed data transmission. Section Seven: Diagnostics. Tests may be used to evaluate the modem's state of operation, its connection, and the communications link between the 14.4K Modem and the remote modem. Section Eight: Troubleshooting. This provides a description of the most common problems which may be encountered during installation and operation along with possible solutions. Appendices. These include technical specifications and FCC compliance information as well as a comprehensive glossary. Contents Introduction Section One: Getting Started (Internal) 1.1 14.4Kbps modem Package 1.2 Communication Settings 1.3 Installing the 14.4Kbps modem 1.4 Connecting the Phone Line 1.4.1 Connecting the Line to the 14.4Kbps Modem 1.4.2 Testing the Connection Section Two: Getting Started (External) 2.1 14.4Kbps modem Package 2.2 Operational Requirements 2.3 Connecting the Phone Line 2.4 Preparing the System 2.5 Testing the Modem 2.6 Testing the Connection Section Three: Data Modem Operation 3.1 Making a Call 3.2 Touch-Tone and Pulse Dialing 3.3 Pause While Dialing 3.4 Using the Hook Flash 3.5 Wait for a Subsequent Dial Tone 3.6 Wait for Silence 3.7 Resume Command State after Dialing 3.8 Switch Hook Control 3.9 Manual Dialing 3.10 Manual Answer 3.11 Controlling the Speaker 3.12 Dial Stored Number 3.13 The AT Command Set 3.13.1 Basic Command Set 3.13.2 Extended Command Set 3.14 S-Registers Section Four: MNP Operation 4.1 Introduction 4.2 MNP Data Mode 4.3 AT Commands for MNP Operation 4.4 S-Register Values for MNP Operation Section Five: Error Correction (V.42bis) 5.1 Introduction 5.2 S-Register Values for Error Correction 5.2.1 Negotiation Fallback 5.2.2 Delay Before Forced Connect 5.2.3 Protocol Selection 5.2.4 Negotiation Action 5.2.5 Bit-Mapped Registers 5.2.7 Connect Failure Cause 5.2.8 Extended Results Code 5.3 AT Commands for Error Correction Section Six:V.32bis/V.32 Operation Section Seven: Diagnostics 7.1 Local Analog Loopback Test 7.2 Local Analog Loopback With Self-Test 7.3 Remote Digital Loopback Test 7.4 Remote Digital Loopback With Self Test Section Eight: Troubleshooting Appendix A: How to Set Bit-Mapped Registers Appendix B: Technical Specifications Appendix C: Compliance Information Glossary Section One: Getting Started: Internal Model This section explains how to install the 14.4Kbps internal Modem into your computer. 1.1 14.4Kbps Modem Package Verify that your modem package contains the following items: * 14.4Kbps modem Board * RJ-11 Telephone Cable * Communication Software and manual * Software diskette containing this file, and sheet with diagrams. 1.2 Communication Settings The 14.4Kbps Modem can be configured as COM1, COM2, COM3, or COM4. The default setting for the modem is COM1 utilizing IRQ4. The following shows standard COM port and IRQ settings: COM1/IRQ4 COM2/IRQ3 COM3/IRQ4 COM4/IRQ3 Because two COM ports will share a single interrupt, you must be careful in choosing which device will share the same interrupt with the modem. Generally, the modem cannot share the same interrupt with any device that is driven by a TSR (terminate and stay resident) program. For example, if you have a mouse on COM1, the modem cannot be set to COM3; if the mouse is on COM2, the modem cannot be set to COM4. One way to avoid interrupt sharing is to select a non-standard interrupt (i.e., IRQ) if it is available, such as IRQ5. However, your communications software must be able to select this non-standard interrupt as well. 1. Remove the 14.4Kbps Modem from its anti-static bag handling it by its edges and metal retaining bracket. Be careful not to touch the edge connector or any of the components on the modem. 2. Determine how many serial ports are already installed in your system. Set the jumpers on the 14.4Kbps Modem for the next available port. See the accompanying illustration for assistance in jumper settings. 1.3 Installing the 14.4Kbps modem This section provides step by step instructions for installing your 14.4Kbps Internal Modem. 1. Power off the computer and disconnect any attached devices and power cords. 2. Remove the computer's cover and locate an available 8- or 16-bit expansion slot. Remove that expansion slot cover and save the screw. 3. Carefully insert the 14.4Kbps modem into the expansion slot applying pressure to the upper metal edge until it snaps into place. 4. Secure the 14.4Kbps modem card into place by aligning the 14.4Kbps modem's metal retaining bracket with the hole in the top edge of the system's unit rear panel. Fasten the metal bracket with the screw removed earlier from the expansion slot cover. 5. Replace the computer cover. 1.4 Connecting the Phone Line An RJ-11 cable is provided with the purchase of your 14.4Kbps modem. This section contains information you will need before you connect the telephone line to the 14.4Kbps modem and explains how to make the proper connections from the 14.4Kbps modem to your telephone line. Before you connect the telephone line to the 14.4Kbps modem, you should familiarize yourself, if you haven't done so already, with the information provided at the beginning of this file concerning FCC and telephone company requirements. 1.4.1 Connecting the Phone Line to the 14.4K Modem 1. Make sure that your computer is still powered down. Plug either end of the RJ-11 cable provided with the 14.4Kbps modem into the "LINE" jack on the modem board. 2. If a phone is connected to the telephone wall jack, unplug the phone cable. Then plug the other end of the 14.4Kbps modem cable into the telephone wall jack. 3. To continue using the phone, connect the phone cable into the "PHONE" jack on the 14.4Kbps modem. See Quick Start! illustration on page 2. 1.4.2 Testing the Connection 1. Check for a dial tone. If a dial tone is heard, proceed with the next step. If you do not hear a dial tone, check the connections you made in the previous subsection (1.4.1) 2. Power on the computer. 3. Load your communications software and put the program into command mode. 4. Type in the command ATZ followed by ENTER and the 14.4Kbps modem will respond with OK after about three seconds. If the 14.4Kbps modem does not respond with OK, refer to the Troubleshooting section of this file. 5. Type ATH1 followed by ENTER and you should hear a dial tone from the speaker on the modem. To adjust speaker volume, see the section on AT Commands. 6. Type ATH followed by ENTER to put the modem on hook. This confirms that the 14.4Kbps modem has been successfully installed into the computer. 7. Your 14.4Kbps internal Modem is now ready for use. Proceed to Section Three for Data Modem Operation. Section Two: Getting Started: External Model This section explains how to connect the 14.4Kbps external Modem to your computer. 2.1 14.4Kbps modem Package Verify that your modem package contains the following items: * 14.4Kbps modem * RJ-11 Telephone Cable * 25-pin to 9-pin RS-232 cable * 9-pin to 25-pin converter * AC adapter with cord * Communication Software and Manual * Software diskette containing this file, and sheet with diagrams. 2.2 Operational Requirements The 14.4Kbps Modem has few requirements and is easy to use. Be sure to read the information on page 1 about connecting to the phone company. In addition, note the following: * The communication settings are controlled by the RS-232 interface present in your system. The external modem is connected to that interface. * Operating the 14.4Kbps modem with a computer requires communication software, either as a stand-alone product as included here, or as part of an application program. * The 14.4Kbps modem takes a DB-25P (25-pin male connector), but computer equipment varies. Check the serial ports at the rear of your machine. * The serial port requires a socket (female connector) or plug (male connector) with either 25 or 9 pins. For example, the IBM PC, XT, and some compatibles require a DB-25S socket connector, while the IBM AT and some compatibles require a DB-9S socket connector. 2.3 Connecting the Phone Line An RJ-11 cable is provided with the purchase of your 14.4Kbps modem. This section contains information you will need before you connect the telephones line to the 14.4Kbps modem and explains how to make the proper connections from the 14.4Kbps modem to your telephone line. Before you connect the telephone line to the 14.4Kbps modem, you should familiarize yourself, if you haven't done so already, with the information provided at the beginning of this file concerning FCC and telephone company requirements. 2.4 Preparing the Modem Follow these simple steps to connect the modem to your computer: 1. Turn off your computer and all peripheral devices. 2. Examine the back of the modem and review the attached interfaces as shown on the accompanying illustration. 3. Check to make sure that power switch is OFF. Then plug the small end of the power adapter into the power jack on the back of the modem, and plug the power adapter into a standard 115V AC wall socket. Disconnect your present phone cord from the wall jack. Plug the end of the phone cord that came with the modem into the wall jack, and the other end into the phone jack at the rear of the modem marked LINE. If you want to keep your telephone connected for conventional calls, plug its cord into the other jack at the rear of the modem labeled PHONE. 4. Lastly, connect the modem to the computer's serial port with the RS-232 cable. Attach the appropriate connectors to the modem and to the serial port. The modem is now ready to be tested and operated. 2.5 Testing the Modem To verify that your modem is working properly, follow these steps: Turn on your computer and clear the screen. Then turn the modem's power switch ON. The following status indicators will flash accordingly as explained on below: Indicator Definition Status TM Test Mode FLASHES when modem is in test mode and if any errors are detected. AA Auto Answer/ ON when in Auto Answer Mode Answer Mode and when online with the host modem. HS High speed ON when the 14.4Kbps modem is powered on or communicating with another modem at 4800 bps or faster. OH Off Hook ON when the 14.4Kbps modem takes control of the telephone line to establish a data link. SD Send Data FLASHES when a data bit is sent to the 14.4Kbps modem by the computer. RD Received Data FLASHES when a data bit is received from the phone line, or when the modem sends result codes to the computer. TR Terminal ON when the modem receives a Ready Data Terminal Ready signal from the computer via the RS-232 cable. CD Carrier Detect ON when the 14.4Kbps modem receives a valid data signal (carrier) from a remote modem. Ready for data transmission. 2.6 Testing the Connection 1. Turn on the modem (PWR toggle switch) and check for a dial tone. If a dial tone is heard, continue with the next step. If you do not hear a dial tone, check the connections you made in 2.4 Preparing the Modem. Also, refer to Section Eight: Troubleshooting. 2. Power on the computer. 3. Load your communications software and put the program into command mode. 4. Type in the command ATZ followed by ENTER and the 14.4Kbps modem will respond with OK. If the 14.4Kbps modem does not respond with OK, refer to the Troubleshooting section of this file. 5. Type ATH1 followed by ENTER and you should hear a dial tone from the speaker on the modem. To adjust speaker volume, see the section on AT Commands. 6. Type ATH followed by ENTER to put the modem on hook. This confirms that the 14.4Kbps modem has been successfully installed into the computer. 7. Your 14.4Kbps external Modem is now ready for use. Proceed to Section Three for Data Modem Operation. Section Three: Data Modem Operation Introduction The purpose of this section is to define the most commonly used Hayes-compatible AT commands for use with your modem. In addition, we've also provided information on extended AT command sets, S-Registers. Subsequent sections discuss commands and registers for high-level protocols such as MNP, V.42/V.42bis, and V.32/V.32bis. Hayes-compatible commands consist of a basic command set and an extended command set. The basic set involves functions such as dialing a number, or putting the modem off- or on-hook (i.e., lifting or replacing the telephone handset). Extended commands allow more sophisticated control of the modem such as transmission speed, or initiating high-level functions like data compression or error correction. These functions are defined and controlled by the available protocols mentioned above. A protocol is a set of standards by which data communications operate. Every AT command includes an AT prefix, followed immediately by the command and, in many cases, additional parameters. Multiple commands can be entered at the same time from the DOS prompt. AT Command[parameter]AT Command[parameter] ... PRESS ENTER Example: ATH or ATH0 tells the modem to disconnect ATH1 tells the modem to connect, or go off-hook. Extended commands were developed to provide greater functionality and control over modem operations. Their format is the same as the basic command except that an additional parameter is required following the AT prefix and before the numerical parameter. This additional parameter comes in three different forms: the ampersand (&) character: extended AT command the backslash (\) character: extended AT command for MNP operation the percent (%) character: extended AT command for V.42/V.42bis Examples: AT&V tells the modem to display (view) its current configuration and user profile (providing the modem has non-volatile RAM, meaning it can store limited amounts of information when power is off. AT\J1 tells the computer to adjust its speed to match line speed when a connection is established. AT%E1 tells the modem to monitor line quality and request a retrain (adjustment) to the connection. S-Registers Modem command language also employs a set of indicators or registers, which are various numerical values all with a standard S prefix, hence S-Registers. To a large extent, the values defined in the S-Registers regulate the operation of the modem and the function of some commands in the AT command set. Example: S-Register 6, or S6=n, defines the length of time the modem will wait for a dial tone. In this case the acceptable range is 2-255 (in seconds) with a default value of 2. With S6=2, the modem will wait two seconds for a dial tone when going off-hook before dialing the first digit of its telephone number. Data Communication Protocols This can be more than a little confusing. These protocols represent various domestic and international standards which enhance modem performance and reliability. The protocols are activated and controlled by a variety of extended AT commands and S-Registers. MNP stands for Microcom Networking Protocol and is a protocol developed by Microcom for full-duplex, error-free communications. This protocol detects and corrects errors which can result from telephone line noise and other signal distortions. There are several classes of MNP operation also referred to as service classes. Class 5 maximizes data transfer rate and provides compression which can significantly increase data throughput. The V-Dot standards are more numerous, but have a single origin: the Consulting Committee for International and Telephone and Telegraph (or CCITT). Some of the lower-level standards such as V.21 and V.22 have domestic equivalents as developed by the former Bell System, also referred to as Bell standards. The V.Dot standards may be summarized as follows: V.21 The CCITT standard for 300bps communications. Domestic modems follow the Bell 103 standard, but V.21 can accept international calls at 300bps. V.22 The CCITT standard for 1200bps communications. The domestic equivalent is the Bell 212A standard. V.22bis The CCITT standard for 2400bps. V.23 CCITT for 1200bps with a 75bps back channel. This is mostly used in Europe and South America. V.32 CCITT standard for 9600bps and 4800bps communications. V.32bis CCITT standard for an extensive class of high-speed modems operating at 14,400bps, 12Kbps, 9600bps, 7200bps, and 4800bps. V.42 CCITT standard for detection and negotiation for LAPM (Link Access Procedure for Modems) error control. V.42 will also support MNP levels 2-4. V.42bis An extension of V.42 specifying the data compression protocol for use with V.42. Basic Modem Operation Use the D command to dial a telephone number with your modem from the command line, i.e., DOS prompt. The format of the command is ATD {string}. The string parameter can contain up to 40 characters, the phone number, and dial modifiers. The dial modifier instructs the modem how to place the call. 3.1 Making a Call To dial, issue the command ATD followed by the phone number. ATD 1234567 [ENTER] The modem dials the telephone number 1234567 and then waits for a carrier from a distant, or remote modem. If no carrier is detected within a given time (default time is 50 seconds), then the modem automatically releases the line and sends a NO CARRIER result code. If a carrier is detected, the modem gives a CONNECT result code and goes on-line, allowing communication with the remote modem. The connection between the two modems end when any of the following occurs: * The local modem loses the carrier signal from the remote modem. * The Hang Up command (ATH) is sent. * The DTR interface signal is dropped between the local DTE and modem with the &D2 or &D3 command in effect. Any of the above actions will cause the modem to hang up, return to command mode, and send the NO CARRIER response. Dial modifiers are summarized as follows: L Re-dial the last dialed string P Pulse dialing (default) T Tone dialing , Pause before sending the next character ! Hook flash W Wait for a subsequent dial tone @ Wait for quiet before proceeding ; Place modem in command state after dialing ^ Disable calling tone. S=n Dial stored number. 3.2 Touch-Tone and Pulse Dialing The modem can be used on telephone lines that require either touch-tone (DTMF) dialing or pulse (rotary) dialing. Pulse dialing is the default method when you turn on the modem but you can switch between pulse and tone dialing by using the P or T dial modifiers. To tell the modem which dialing method to use, type P or T in front of the numbers to be dialed. Examples: Touch-Tone Dialing: AT D T 555-1212 [ENTER] Pulse Dialing: AT D P 555-1212 [ENTER] Touch-tone and pulse dialing can also be combined in a dial command line when both dialing methods are required. The following command line is used to dial through a PBX that uses touch-tone dialing and the outside lines require pulse dialing: AT D T 9 W P 555-1212 [ENTER] This command line tells the modem to touch-tone dial 9 to get an outside line, wait (W) for a secondary dial tone (see Section Four on S-Registers), and then pulse dial the number 555-1212. 3.3 Pause While Dialing The , (comma) dial modifier causes the modem to pause while dialing. The modem will pause the number of seconds specified in the Register S8 and then continue dialing. The default value of Register S8 is two seconds. If a pause time longer than 2 seconds is necessary, it can be increased by either inserting more than one , in the dial command line or changing the value of Register S8. An example of a typical dial command line follows: AT D 9, 555-1212 [ENTER] This command accesses the outside (public) telephone line with the 9 parameter. The modem then waits 2 seconds with the , and then dials the telephone number 555-1212. 3.4 Using the Hook Flash The ! dial modifier causes the modem to go on-hook (hang up) for one-half second and is equivalent to holding down the switch-hook on your telephone for one-half second. This feature is useful when transferring calls. 3.5 Wait for a Subsequent Dial Tone The W dial modifier causes the modem to wait for an additional dial tone before dialing the numbers that follow the W. The length of time the modem waits is up to the value in Register S7 (default is 50 seconds). The modem can be instructed to dial through PBXs (Private Branch Exchanges) or long-distance calling services that require delays during dialing. This can be done with the W command to wait for a secondary dial tone or with a , command to pause for a fixed time and then dial. An example of a Dial command line when dialing through a PBX follows: AT D 9 W 555-1212 [ENTER]. The 9 accesses the outside (public) telephone line. The W causes the modem to wait 50 seconds for a secondary dial tone (unless the default value of Register S7 has been changed). The 555-1212 is the telephone number to be dialed. 3.6 Wait for Silence The @ command causes the modem to listen for 5 seconds of silence. If a 5-second silence has not been detected within the period specified in the S7 register (default is 50 seconds), the modem disconnects and returns the NO ANSWER result code. If it detects a busy signal, it returns a BUSY result code. If the 5 seconds of silence is detected, then the modem continues dialing the dial string. Example: AT DT 9 @ 1 (215) 555-1212 [ENTER] 3.7 Resume Command State after Dialing The ; (semicolon) dial modifier returns the modem to the command state after dialing the telephone number. The ; must come at the end of the command line. It does not connect to the remote modem, but holds the line for additional commands. When the modem has finished dialing the number, it returns the OK message. The semicolon dial modifier is useful when the number to be entered exceeds 40 characters. The semicolon dial modifier, breaks the number into two commands. Example: AT DT 1 123 456; [ENTER] OK AT DT 7890 [ENTER] These two commands dial a single phone number with the ; in the first command causing the modem to return to command mode without releasing the line. The second command dials the remaining numbers and makes the connection to the modem. 3.8 Switch Hook Control The H command is used to control the telephone line relay. This command is most commonly used to hang up the phone from command mode. The format of the command is ATHn where the n parameter (optional) governs how the line relay is controlled. Either ATH or ATH0 causes the phone line relay to go on-hook (disconnect). ATH1 causes the phone line relay to go off-hook (connect). 3.9 Manual Dialing To manually dial the phone, you should be in your communications software's command mode. Lift the receiver of the telephone and dial the number you wish to call. Type ATH1 [ENTER] to connect the modem and then hang up the receiver. Type ATO [ENTER] to tell the modem to go on-line. 3.10 Manual Answer When the automatic answer feature (Register S1) is not being used, incoming calls can be answered manually by typing ATA [ENTER] when an incoming call is received. The modem will answer the incoming call and enter on-line mode. 3.11 Controlling the Speaker The audio speaker is controlled by the M command. It can be adjusted with the following commands. Default settings are highlighted: AT M0 Turns the speaker off ATM1 Turns the speaker on until carrier is detected (DEFAULT) AT M2 Leaves the speaker on at all times AT M3 Turns the speaker on until carrier is detected except during dialing The L command is used to adjust the speaker volume. The volume levels available are: AT L0, 1 Selects low volume AT L2 Selects medium volume (DEFAULT) AT L3 Selects high volume 3.12 Dial Stored Number This number follows the dial command string, causing the modem to dial a telephone number previously stored using the command AT&Z. Up to four entries may be stored and used (0-3). 3.13 The AT Command Set The 14.4Kbps MODEM supports the standard and extended Hayes AT command set. These commands are the industry-standard language used to communicate with the modem. To use these commands, load your communications software package and enter into command mode. NOTE: AT commands pertaining to MNP, V.32bis/V.32, and V.42bis/V.42 operation are discussed in their own sections. The modem is always in one of three modes: the command mode, fax mode, or data mode. The modem enters command mode when it is turned on or reset, when it loses a connection with a remote modem, or when it is in on-line mode and you type certain escape characters. When the modem is in command mode, it accepts instructions in the form of commands and return responses. This mode allows the modem to be configured for a particular application or instructed to perform a function. These settings will remain active until the computer has been turned off except for configuration profile stored in non-volatile RAM. The modem then returns to its default settings. The modem enters data mode when it has made a connection with a remote modem and sends the CONNECT response confirming the connection has been established. Data can then be exchanged. Every modem command must begin with the characters AT, with the exception of the A/ command which is described later in this section. The AT characters are called the attention code. They signal the modem that one or more modem commands will follow. There are specific command line guidelines that must be followed: * Command lines must begin with the AT prefix. Characters must be in all uppercase or all lowercase. * Command lines may contain up to 40 characters. * Space characters in the command line are ignored. * Command lines must end by pressing the ENTER key * Line feed character after carriage return is optional and ignored by the modem. * Multiple commands may appear on a single line. * An error in the command line may be corrected by using the backspace key, with the exception of the AT prefix. Control-H can be used if the keyboard does not have a backspace key. Note: Use the command AT&V to display the active configuration and stored user profiles. On-Line State To transmit or receive data, the modem must be in the on-line state. When placing a call, the modem is put on-line with the dial command. At the remote end, the modem goes on-line when it is instructed to answer a call automatically by setting the Register S0 equal to any number greater than 0 and less than 255. You can also perform this function with the ATA command. Escape Sequence After a connection has been established with a remote modem, you can return to command mode without breaking that connection by typing the escape sequence. The escape sequence consists of three plus characters (+++). It is not necessary to begin this sequence with the AT attention code, nor do you need to press ENTER after typing the escape code. Return to On-Line State The modem can be returned to the on-line state after the escape sequence has been issued. To return the modem to the on-line state, issue the ATO command. To return the modem on-line and then initiate and equalized retrain sequence, use the command ATO1. Re-executing the Last Command Line Each command line sent to the modem remains in the command buffer until the next AT command is sent or until power to the modem is turned off. To repeat the last command issued, type in the command A/. The A/ command is neither preceded by the AT characters nor followed by ENTER. Omitting a Parameter Some commands require a parameter to completely define them. If a parameter is omitted from a command that requires one, the command will respond with the default value. Result Codes A response is sent by the modem after executing, or trying to execute a command. The response displays the modems status or the progress of a call, and can take the form of either words or digits. The default consists of word responses which are defined with the V1 command. To receive digit responses rather than word responses, use the V0 command. To disable the responses entirely, use the Q1 command. The tables on the next four pages list the word responses the modem can return, their numeric equivalent, and a short description of each. Result Codes Result Numeric Code Value Description OK 0 Modem successfully executed a command line. CONNECT 1 Connection made at 300 bps. RING 2 Modem detected an incoming call. NO CARRIER 3 Modem lost or could not detect a remote carrier signal within the Register S7 time. ERROR 4 Modem found an error in the command line. CONNECT 1200 5 Modem established a connection 1200 at 1200 bps. NO DIALTONE 6 Modem did not detect a dial tone within 5 seconds after going off-hook. BUSY 7 Modem detected a busy signal. NO ANSWER 8 Five seconds of silence was not detected when using the @ command in the dial command line. CONNECT 0600 9 Modem established a connection at 600 bps. CONNECT 2400 10 Modem established a connection at 2400 bps. CONNECT 4800 11 Modem established a connection at 4800 bps. CONNECT 9600 12 Connection made at 9600 bps. +FCERROR +F4 Fax carrier error. CONNECT 7200 13 Connected as data modem during an answer. CONNECT 12000 14 Connection made at 12000 bps. CONNECT 14400 15 Connection made at 14400 bps. CONNECT 19200 16 Connection made at 19200 bps. CONNECT 38400 17 Connection made at 38400 bps. CONNECT 57600 18 Connection made at 57600 bps. CONNECT 75TX/ 22 1200RX Modem returns this result code when upon establishing a V.23 originate connection when the modem has been instructed to report the DTE speed to the DTE upon connecting. CONNECT 23 1200RX/75RX Modem returns this result code when upon establishing a V.23 answer connection when the modem has been instructed to report the DTE speed to the DTE upon connecting. CARRIER 300 40 Carrier rate of 300 bps. CARRIER 1200/ 44 V.23 backward channel has been detected. 75 CARRIER 75/ 45 V.23 forward channel has been detected 1200 CARRIER 1200 46 Carrier rate of 1200 bps. CARRIER 2400 47 Carrier rate of 2400 bps. CARRIER 4800 48 Carrier rate of 4800 bps. CARRIER 7200 49 Carrier rate of 7200 bps. CARRIER 9600 50 Carrier rate of 9600 bps. CARRIER 12000 51 Carrier rate of 12000 bps. CARRIER 14400 52 Carrier rate of 14400 bps. COMPRESSION: CLASS 5 66 The modem has connected in MNP class 5 and COMPRESSION message reporting has been enabled. COMPRESSION: V.42bis 67 The modem has connected in V.42bis and COMPRESSION message reporting has been enabled. COMPRESSION: NONE 69 The modem has connected without data compression and COMPRESSION message reporting has been enabled. 3.13.1 Basic Command Set The following tables list the AT commands and their functions. Default settings are indicated. Command Options Description A none Answer command. The modem will go off-hook, transmit the answer tone, and wait for a carrier from the remote modem. A/ none Re-execute last command. The last command executed by the modem will execute again. This command does not require the AT prefix or ENTER. AT none Attention characters. The AT command must appear at the beginning of each command line or the modem will not execute the command line. Bn Select communications standard. n=0 Selects V.22 2100 Hz answer tone at 1200 bps. (DEFAULT) n=1 Selects Bell 212A 2225 Hz answer tone at 1200bps. Cn Turn modem transmit carrier signal on or off. n=0 Transmit carrier signal off. (DEFAULT) n=1 Transmit carrier signal on. D none Dial command. Puts the modem into originate mode, allowing it to work as an auto-dialer for connecting to another modem. See Section Two for additional information. En Echo back command characters. n=0 Disables echoing of commands to the screen. n=1 Enables echoing of commands to the screen. (DEFAULT) Fn Select Line Modulation. Selects the line modulation according to the parameter supplied. n=0 Auto-detect mode. n=1 Selects V.21 or Bell 103 according to the AT B command setting. n=2 Not supported. n=3 Selects V.23. n=4 Selects V.22 or Bell 212A 1200. n=5 Selects V.22bis 2400. n=6 Selects V.32bis 4800 or V.32 4800. n=7 Selects V.32bis 7200. n=8 Selects V.32bis 9600 or v.32 9600. n=9 Selects V.32bis 12000. n=10 Selects V.32bis 14400. Hn Switch hook control. n=0 Instructs the modem to go on-hook (hang-up or disconnect). n=1 Instructs the modem to go off-hook and enter command mode. In Identification. Requests the modem to return its product identification information. n=0 Displays the product identification code. n=1 Displays the ROM checksum. n=2 Displays ROM checksum as OK or ERROR. n=3 Displays the firmware revision level. n=4 Displays OEM-defined identifier string. n=5 Displays country code number. n=6 Displays modem data pump model. Ln Speaker volume. n=0 Off or low volume. n=1 Low volume. (DEFAULT) n=2 Medium volume. n=3 High volume. Mn Speaker Control. n=0 Disables the modem speaker. n=1 Turns on the modem speaker until carrier has been detected.(DEFAULT) n=2 Instructs the modem speaker to stay on at all time. n=3 Enables speaker after dialing until connection is established. Nn Automode Enable. n=0 Requires the speed of the connection be that specified by the value of S37. n=1 Permits handshaking at any speed supported by both modems. (DEFAULT) On Return to on-line state mode. n=0 Switches the modem from command mode to on-line mode without dialing. n=1 Switches from command mode to on-line mode and initiates an equalizer retrain sequence during 2400 bps operation. Qn Modem responses enabled or disabled. n=0 Enables result codes to be issued to the screen. (DEFAULT) n=1 Disables result codes to be issued to the screen. Sn Change the value of an S-Register. n is the number of the register whose value is to be changed (0-95) and n is the new value (0-255). Sn? Read the value of an S-register. n is the number of the register whose value is to be read (0-95). Vn Result code format. n=0 Numeric format. n=1 Verbal format. (DEFAULT). Wn Error Correction Message Control n=0 Report DTE speed in error correction mode. (DEFAULT) n=1 Report line speed, error correction protocol, and DTE speed. n=2 Report DCE speed in error correction mode. Xn Extended Result Codes. Determines which set of responses and calling characteristics are used. X3 allows blind dialing to be enabled by country parameters. X4 sends all messages. Response Code n=0 n=1 n=2 n=3 n=4 0 (OK) X X X X X 1 (CONNECT) X X X X X 2 (RING) X X X X X 3 (NO CARRIER) X X X X X 4 (ERROR) X X X X X 8 (NO ANSWER) X X X X X * (CONNECT XXXX) X X X X X 6 (NO DIAL TONE) O O X X X 7 (BUSY) O O O X X * Numeric response codes for "CONNECT" are 5, 9-12, 13-18, 22-23, 40, and 44-52. 1 (CONNECT) is a 300bps connection. Yn Control Long Space Disconnect. Determines whether or not modem disconnects when it receives a continuous break from a remote modem. n=0 Disabled. (DEFAULT) n=1 Enabled. Zn Soft Reset and Restore Profile. n=0 Restores stored profile 0. n=1 Restores stored profile 1. +++ none Escape characters. The escape characters are known as +++. They will switch from on-line mode to command mode while preserving the connection to the remote modem. This command allows a parameter to be checked or changed after connecting with a remote asynchronous modem. Escape characters involve a timed pause of 1 second (specified in Register S12), three keystrokes of the + escape character defined by Register S2) and another pause (again specified in Register S12). ? S-register contents. Displays the contents of the last addressed S-register. 3.13.2 Extended Command Set Commands Options Description &Cn Data Carrier Detect (DCD) signal. n=0 Forces DCD signal to be on at all times. (DEFAULT) n=1 DCD on indicates presence of data carrier. &Dn Data Terminal Ready (DTR) signal. Interprets the ON to OFF transition of the DTR signal from the DTE according to the & setting as follows: n=0 &Q 0, 5, 6. DTR ignored &Q 1, 4. Modem hangs up; auto-answer not affected. &Q 2,3. Modem hangs up; auto-answer inhibited. (DEFAULT) n=1 &Q 0, 1 4-6. Asynchronous escape sequence. &Q 2,3. Modem hangs up; auto-answer inhibited. n=2 &Q 0-6. Modem hangs up; auto-answer inhibited. n=3 &Q 0, 1 4-6. Modem does a soft reset as if the Z command were received; &Y determines which profile is loaded. &Q 2,3. Modem hangs up; auto-answer inhibited. &F Recall factory defaults. Instructs the modem to use the factory set parameters. n=0 Recall (restore) factory profile 0. n=1 Recall (restore) factory profile 1. &Gn Guard tone select in CCITT mode. Guard tones are always disabled in the U.S.A. n=0 Do not use guard tones. (DEFAULT) n=1 Disables guard tone. n=2 Selects a guard tone 1800 Hz. &Jn Telephone Jack Control. Included only for compatibility and performs no function other than to load the value of S Register 21 (n= 0 or 1). &Kn DTE/Modem Flow Control. Determines how the modem controls the flow of data between the local DTE and the modem. When the modem terminal buffer is nearly full, the modem will either send an XOFF or drop CTS to stop the data flow; when the buffer is nearly empty, the modem will either send an XON or raise CTS to resume the data flow. n=0 disable flow control n=3 enable RTS/CTS (DEFAULT for data modem) n=4 enable XON/XOFF n=5 enable transparent XON/XOFF n=6 enable both RTS/CTS and XON/XOFF (DEFAULT for fax modem) Note on Flow Control. XON/XOFF is a software-based flow control method, using standard ASCII control characters to pause or resume data transmission. RTS/CTS pacing, a hardware-based method, uses an electrical signal. Signals are exchanged as follows: RECEIVER TRANSMITTER CTS ON ------> START SENDING CTS ON <------ RTS ON (ready to send) CTS OFF ------>RTS OFF (stop sending) &Ln Line selection. Informs the modem of the type of telephone line to which it will be connected. (NOT SUPPORTED) n=0 Selects a dialup telephone line. (DEFAULT) n=1 Selects a leased telephone line. Each modem on a leased line has its transmitters turned on continuously, allowing transmission to occur in both directions at the same time. &Mn Asynchronous/Synchronous Mode Selection. Determines the DTR operating mode. The modem treats the &M command as a subset of the &Q command. n=0 Selects direct asynchronous mode. (DEFAULT) n=1 Selects synchronous connect mode with asynchronous off-line command mode. n=2 Same as &M1 except modem will disconnect if DTR is OFF for more than the period in S25. n=3 Selects synchronous connect mode with asynchronous off-line command mode. This mode allows the DTR to act as a talk/data switch. The call is initiated while the DTR is inactive. &Pn Select Pulse Dial Make/Break ratio. Determines the ratio between the off-hook (make) and the on-hook (break) pulse dialing intervals. n=0 Selects a make/break ratio of 39/61 at 10pps. Used in the United States and Canada. (DEFAULT) n=1 Selects a make/break ratio of 33/67 at 10pps. Used in the United Kingdom and Hong Kong. n=2 Same as 0 except at 20pps. n=3 Same as 1 except at 20pps. &Qn Sync/Async Mode. An extension of the &M command and is used to control the connection modes permitted. Used in conjunction with S36 and S48 (see also \N). n=0 Direct asynchronous mode. n=1 Synchronous connection with asynchronous off- line command mode. n=2 Same as 1 plus enable DTR dialing of directory zero. n=3 Same as 1 plus enable DTR to act as talk/data switch. n=4 Hayes auto-synchronous mode. n=5 Modem negotiates an error-corrected link. (DEFAULT) n=6 Selects asynchronous operation in normal mode (i.e., speed buffering). &Rn RTS/CTS Option. Controls the state of the CTS signal. CTS is always on in the asynchronous mode unless AT&K3 has been selected. n=0 CTS tracks RTS. n=1 CTS is always active (DEFAULT). &Sn Data Set Ready (DSR) signal. n=0 Causes DSR signal to be active at all times. (DEFAULT) n=1 Causes DSR signal to be active according to the V.25 protocol. &Tn Test and Diagnostics. Refer to the Diagnostics section for more information. n=0 Terminates any test in progress. n=1 Executes the local analog loopback test. n=3 Executes the local digital loopback test. n=4 Enables the modem to accept a request from a remote modem for a digital loopback test. (DEFAULT) n=5 Instructs the modem to deny a request from a remote modem for a digital loopback test. n=6 Executes the remote digital loopback test. n=7 Executes the remote digital loopback test with a self test. n=8 Executes the local analog loopback test with a self test. &V none View current configuration and user profile. Displays the active configuration and stored user profiles. &Wn Store user profile. Saves the current configuration into non-volatile RAM as one of two user profiles. Also use this command to write initialization strings. n=0 saves as user profile 0. n=1 saves as user profile 1. &Xn Select Synchronous Clock Source. Selects the source of the transmit clock for the synchronous mode of operation. The parameter value, if valid, is written to S27 (bits 4 and 5). In asynchronous mode, the transmit and receive clocks are turned OFF. (EXTERNAL modem only) n=0 Selects internal timing. n=1 Selects external timing. n=2 Selects slave receive timing. The transmit clock signal is derived from the incoming carrier. &Yn Designate Default User Profile. Specifies which of two user profiles will be loaded into the active configuration at power-up. n=0 Selects user profile 0. n=1 Selects user profile 1. &Zn=x none Store Phone Number. Stores a 36-digit dial string (x) in the specified entry (0-3) for later dialing. See the ATDS=n command (3.12 Dial Stored Number). An individual entry may be made up to 40 digits, but the total number of digits in all entries may not exceed 114. S=n none Dial Stored Number. Follows the dial command string, causing the modem to dial a telephone number previously stored using the AT&Zn command. 3.14 The S-Registers This section defines the purpose of the modem registers, explains how to read and change register values, how to access a register repeatedly, and sequentially lists the registers and describes their functions. These registers affect various operating characteristics and allow you to obtain information about the modem, as well as test the modem. Each register has a factory-set value, which you can read or change to fit your needs. To learn how to set bit-mapped registers and how their values are calculated, refer to Appendix A. Reading a Register Value To read the current value of a register, type: AT Sn? [ENTER], where n is a register number. The modem will respond with the decimal value of the register in three digit form. This will be followed by OK or 0. To read values from more than one register, type: AT Sn? Sn? [ENTER] from the command mode. To read the register values of S0 and S1, type AT S0? S1? [ENTER] The modem will display the first register value, a carriage return, the next register value, a carriage return, and OK or 0. Changing a Register Value To change a register value, use the Sn command (ATSn=v), where n is a register number and v is the new value you want to assign to the register. Type: AT S0=3 [ENTER] to have the modem automatically answer incoming calls after the third ring. The changed values remain in effect until the modem is turned off and on or reset. The modem then returns to its default settings. Accessing a Register Repeatedly The modem automatically places a pointer at the last register whose value was read or changed. The pointer provides a fast way of displaying or changing register values. Type: AT S0? [ENTER] to read the value of Register S0. The modem responds with the value of Register S0 and places a pointer at that register automatically. Type: AT=0 [ENTER] to change the value in Register S0 to 0. (Neither the S command nor the register number has to be specified; the pointer handles this task.) Type: AT? [ENTER] to read the S0 value. NOTE: The pointer remains set at the last register accessed until the S command is used to read or change the value of a different register. The pointer is then set to the register whose value is displayed or changed. S-Register Descriptions The following table lists the modems registers and their functions. Reg. Range Units Default Definition S0 0-255 rings 2 Auto-answer Description: Holds the number of rings the modem will wait before answering the phone. If this register is set to zero, the modem will not answer the phone. In terminal mode, make sure this is ON (S0 equal to anything but zero) with %C1 and %D1 in the active profile. S1 0-255 rings 0 Count incoming rings Description: Counts the number of rings detected on the line. The register is cleared if a ring is not detected over an eight second time period. If the register value equal the value contained in S0, the modem will answer the phone. S2 0-255 rings 43 Escape character value. Description: Contains the ASCII value of the character used as the Escape Code. This enables the modem to switch from on-line mode to command mode without losing the connection to the remote modem. S3 0-127 ASCII 13 Carriage return character. Description: Contains the ASCII value of the character used to send a carriage return. This character terminates both command lines and result codes. S4 0-127 ASCII 10 Line feed character. Description: Contains the ASCII value of the character used to send a line feed. The modem sends the line feed character after a carriage return only when word responses are sent. S5 0-32 ASCII 8 Backspace character. Description: Contains the ASCII value of the character used to backspace. This character is both the character created by pressing the Backspace key and the character echoed to move the cursor to the left. S6 2-255 seconds 2 Wait time for Blind Dialing. Description: Sets the length of time to pause after the modem goes off-hook before the modem dials the first digit of the telephone number. S7 1-255 seconds 50 Wait for carrier after dial. Description: Defines two delay times: (1) time that the local modem waits for the carrier from the remote modem before hanging up; (2) time that the modem waits when the Wait for Dial Tone call progress feature (W in dial string) is in effect. S8 0-255 seconds 2 Pause time for dial delay. Description: Determines how long the modem should pause when it sees a comma in the dialing string. S9 1-255 seconds 6/10 Carrier detect. Description: Determines the amount of time in tenths of a second from when the modem recognizes a loss of carrier to when it will hang up. S10 1-255 seconds 14 (1.4) Lost Carrier to Hang Up Delay. Description: Sets the length of time tenths of a second, that the modem waits before hanging up after the loss of a carrier. This allows for a temporary carrier loss without causing the local modem to disconnect. When register S10 is set to 255, the modem functions as if a carrier is always present. The actual interval the modem waits before disconnecting is the value in S10 minus the value in S9. If this value is set smaller than the value contained in S9, the modem disconnects before it recognizes its carrier. S11 Reserved. S12 0-255 seconds 50(1) Escape code guard time*. Description: Controls the delay time before and after typing escape sequence codes. *in one-fiftieth second increments S13 Reserved. S14 Bit Mapped AA,hex Bit mapped registers. Provides the following functions (defaults are highlighted): BIT Definition and Options Bit 0 IGNORED Bit 1 ATE (command echo) 0 Do not echo commands 1 Echo commands (DEFAULT) Bit 2 ATQ (result code display) 0 Send responses (DEFAULT) 1 Do not send responses Bit 3 ATV (word or number responses) 0 Send number responses 1 Send word responses (DEFAULT) Bit 4 RESERVED. Bit 5 Dial Method (ATP or ATT) 0 Touch-Tone (T) (DEFAULT) 1 Pulse (P) Bit 6 RESERVED. Bit 7 Answer/originate operation 0 Answer (A and R) 1 Originate (D) (DEFAULT) S15 Reserved S16 Bit Mapped 80,hex Modem test options. Provides the following functions (defaults are highlighted): Bit Definition and Options Bit 0 Local analog loopback test 0 Disabled (&T0) (DEFAULT) 1 Enabled (&T) Bit 1 NOT USED Bit 2 Local digital loopback test 0 Disabled (&T0) (DEFAULT) 1 Enabled (&T3) Bit 3 Remote digital loopback test 0 Disabled (&T0) (DEFAULT) 1 Enabled (&T6) Bit 4 Initiate remote digital loopback 0 Loopback not in progress (&T0) (DEFAULT) 1 Loopback in progress (&T7) Bit 5 Remote digital loopback with error count 0 Disabled (&T0) (DEFAULT) 1 Enabled (&T7) Bit 6 Local analog loopback with self test 0 Disabled (&T0) (DEFAULT) 1 Enabled (&T8) Bit 7 NOT USED S17 Reserved S18 0-255 seconds 0 Test timer. Description: Determines how long a diagnostic test will be allowed to run before being returned to the command mode. The test timer is disabled with the value set to zero. S19 Reserved S20 Reserved S21 Bit Mapped Bit mapped registers. 00,hex Provides the following functions: Bit Definition and Options Bit 0 Telephone jack type 0 RJ-11, RJ-41S, RJ-45S (&J0) (DEFAULT) 1 RJ-12, RJ-13 (&J1) Bit 1 RESERVED Bit 2 RTS (Request to Send)/CTS(Clear to Send) (&Rn) 0 CTS tracks RTS (DEFAULT) 1 Modem ignores RTS Bit 3,4 Data Terminal Ready (DTR) (&Dn) 0 = &D0 selected (DEFAULT) 1 = &D1 selected 2 = &D2 selected 3 = &D3 selected Bit 5 Data Carrier Detect (DCD) 0 DCD is always active (&C0) (DEFAULT) 1 DCD is active when remote carrier is detected (&C1) Bit 6 Data Set Ready (DSR) 0 DSR is always active (&S0) (DEFAULT) 1 DSR is active when handshaking begins (&S1) Bit 7 Long space disconnect 0 Disabled (Y0) (DEFAULT) 1 Enabled (Y1) S22 Bit Mapped 75,hex Bit mapped registers. Provides the following functions (asterisk indicates default): Bit Definition and Options Bit 0, 1 Speaker volume 0 = OFF (L0) 1 = Low volume (L1) (DEFAULT) 2 = Medium volume (L2) 3 = High volume (L3) Bit 2, 3 Speaker Control 0 = Speaker turned off (M0) 1 = Speaker on until carrier detected (M1) (DEFAULT) 2 = Speaker always on (M2) 3 = Speaker on until carrier detected, off when dialing (M3) Bit 4, 5, 6 Limit Result Codes 0 = X0 4 = X1 5 = X2 6 = X3 7 = X4 (DEFAULT) Bit 7 Reserved. S23 Bit Mapped 07, hex Bit mapped registers. Provides the following functions. Defaults are highlighted. Bit Definition and Options Bit 0 Request from remote modem for digital loopback test. 0 Ignore request (&T5) 1 Grant request (&T4) (DEFAULT) Bit 1, 2, 3 Communications Rate 0 0-300 bps 1 600 bps 2 1200 bps 3 2400 bps (DEFAULT) 4 4800 bps 5 9600 bps 6 19200 bps Bit 4,5 Parity Setting 0 even 1 not used 2 odd 3 none Bit 6, 7 Guard Tones 0 = none (&G0) (DEFAULT) 1 = none (&G1) 2 = 1800 Hz (&G2) S24 0-255 seconds 0 Sleep Inactivity Timer. Description. Sets the length of time that the modem operates in normal mode with no line activity before entering low power sleep mode. S25 0-255 seconds 5 Asynchronous DTR Delay Description: Determines the time interval that the modem will ignore a change in the DTR status. S26 0-255 seconds 1 Delay Interval. Description: RTS to CTS delay interval (in hundredths of a second). S27 Bit Mapped Bit mapped registers. 9, hex Bit 0, 1, and 3 are reserved. Bit Definition and Options Bit 2 Line Type (NOT SUPPORTED) 0 Dialup line (&L0) 1 Leased line (&L1) Bit 4,5 Clock Source Selection 0 Internal clock (&X0) (DEFAULT) 1 External clock (&X1) 2 Slave clock (&X2) Bit 6 0 CCITT V.22/V.22bis standard (B0)(DEFAULT) 1 Bell 212A standard (B1) Bit 7 Reserved. S28 Bit Mapped Bit mapped registers Bit Definition and Options Bit 0 V.23 split speed (\Wn) (DEFAULT) 0 = Disabled (\W0) (DEFAULT) 1 = Enabled (\W1) Bit 1 V.23 split speed direction 0 = 75bps transmit (%F0) (DEFAULT) 1 = 1200bps transmit (%F1) Bit 2 V.23 half-duplex 0 = disabled (DEFAULT) 1 = enabled (%F3) Bit 3, 4 Pulse dialing (&Pn) 0 = 512 (&P0) (DEFAULT) 1 = 1024 (&P1) 2 = 2048 (&P2) 3 = 4096 (&P3) Bit 5, 6, 7 Reserved S29 Reserved. S30 0-255 seconds 0 Inactivity Timer Description: Determines the length of time (in tens of a second) that the modem will wait before disconnecting when no data is sent or received. S31 2 Bit Mapped Options Bit Definition and Options Bit 0 RESERVED Bit 1 Controls auto line speed detection. 0 = disabled (N0) 1 = enabled (N1) (DEFAULT) Bit 2,3 Controls error correction progress messages (Wn) 0 = DTE speed only (W0) (DEFAULT) 1 = full reporting (W1) 2 = DCE speed only (W2) Bit 4-7 RESERVED S32 0-255 ASCII 17 XON Character Description: Sets the value of the XON character. S33 0-255 ASCII 19 XOFF Character Description: Sets the value of the XOFF character. S34-35 Reserved. S36 7 Bit Mapped Options Bit Definition and Options Bit 0-2 Indicates what happens during a LAPM failure. These fallback options take effect immediately upon connection if S48=128. If an invalid number is entered, the number is accepted into the register, but S36 acts as if the default value has been entered. 0 = modem disconnects 1 = modem stays online; establishes a direct mode connection. 2 = Reserved. 3 = modem stays online; establishes a normal mode connection. 4 = attempts MNP connection; if it fails, modem disconnects. 5 = attempts MNP connection; if it fails, establishes a direct mode connection. 6 = Reserved. 7 = attempts MNP connection; if it fails, establishes a normal mode connection. (DEFAULT) Bit 3-7 Reserved. S37 0-12 0 Telephone Line Speed Description: Desired Line Connection Speed. This is interlinked with the Fn command. If an invalid number is entered, the number is accepted into the register, but S37 will act as if the default value has been entered. Bit Definition and Options Bit 0-3 0 = Attempt auto mode connection (F0) (DEFAULT) 1-3 = Attempt to connect at 300 bps. (F1) 4 = Reserved. 5 = Attempt to connect at 1200 bps. (F4) 6 = Attempt to connect at 2400 bps. (F5) 7 = Attempt to connect at V.23 at 600/1200 bps. (F3) 8 = Attempt to connect at 4800 bps. (F6) 9 = Attempt to connect at 9600 bps. (F8) 10 = Attempt to connect at 12K bps. (F9) 11 = Attempt to connect at 14.4Kbps (F10) 12 = Attempt to connect at 7200 bps. (F7) Bit 4-7 RESERVED. S38 0-255 seconds 20 Delay Before Forced Hangup Description: Specifies the delay between the modems receipt of the H command to disconnect. Applies to error correction only. This register can be used to ensure that data in the buffer is sent before the modem disconnects. If S38=0-254, the modem will wait that number of seconds before disconnecting. If S38=255, the modem does not time out and continues to deliver data in the buffer until the connection is lost or the data is delivered. S39 Bit Mapped 3 Bit Mapped Registers Bit Definition and Options Bit 0-2 Status of Command Options 0 = no flow control 3 = RTS/CTS (&K3) (DEFAULT) 4 = XON/XOFF (&K4) 5 = Transparent XON/XOFF (&K5) 6 = Both methods (&K6) Bits 3-7 Reserved S40 Bit Mapped 105 Bit Mapped Registers Bit 0 MNP Extended Services 0 = disabled (-K0) 1 = enabled (-K1) (DEFAULT) Bit 1 Power Level Adjustment for Cellular Use ()Mn) 0 = auto adjustment ()M0) (DEFAULT) 1 = force adjustment ()M1) Bit 2 MNP Link Negotiation Speed (*H1) 0 = highest speed (*H0) (DEFAULT) 1 = 1200 bps (*H1) Bits 3-5 Break Handling (\Kn) 0 = \K0 1 = \K1 2 = \K2 3 = \K3 4 = \K4 5 = \K5 (DEFAULT) Bits 6-7 MNP Block Size 0 = 64 chars. (\A0) 1 = 128 chars. (\A1) 2 = 192 chars. (\A2) (DEFAULT) 3 = 256 chars. (\A3) S41 Bit Mapped 3 Bit Mapped Registers (for MNP) Bits 0-1 Compression selection (%Cn) 0 = disabled (%C0) 1 = MNP5 (%C1) 2 = V.42bis (%C2) 3 = MNP5 and V.42bis (%C3)(DEFAULT) Bit 2 Auto retrain 0 = retrains disabled (%E0) (DEFAULT) 1 = retrains enabled (%E1) Bit 3 Modem to Modem Flow Control 0 = disabled (\G0) (DEFAULT) 1 = enabled (\G1) Bit 4 Block Mode Control 0 = stream mode (\L0) (DEFAULT) 1 = block mode (\L1) Bits 5-7 Reserved S42-45 Reserved S46 136 or 138 138 Data Compression Control 136 = error correction protocol with no compression 138 = error correction protocol with compression (DEFAULT) S48 0, 7, 128 7 V.42 Negotiation Action 0 = Disable negotiation and proceed with LAPM. 7 = Enable negotiation. (DEFAULT) 128 = Disable negotiation and proceed with fallback action specified in S36. S49-81 Reserved S82 3, 7, 128 128 Break Handling Option Description: Used to get the attention of the remote modem. Three types of break signals are provided: 3 = Expedited. Modem sends a break immediately; data integrity is maintained. 7 = Destructive. Break is sent immediately and data being processed at time of break is destroyed. 128 = In Sequence. Modem sends a break in sequence; data integrity is maintained (DEFAULT). S86 N/A Connection Failure Cause Code Description: When the modem issues a NO CARRIER result code, a value is written to the S register to help determine the cause for the failed connection. The values are as follows: 0 = normal disconnect; no error occurred. 4 = loss of carrier 5 = V.42 negotiation failed to detect an error correction modem at the other end. 9 = the modems could not find a common protocol. 12 = normal disconnect initiated by remote modem. 13 = remote modem does not respond after 10 re-transmissions of the same message. 14 = protocol violation. S91 0 to -15 dBm 10 PSTN Transmit Level Description: Sets the transmit level, in dBm, for the PSTN mode. In some countries, this level cannot be changed and there are checks to prevent transmit level change. S92 0 to -15 dBm 10 Fax Transmit Level Description: Sets the transmit level, in dBm, for the fax mode. In some countries, this level cannot be changed and there are checks to prevent transmit level change. S95 SEE SECTION 4.4: S-Registers for MNP Operation Section Four: MNP Operation 4.1 Introduction MNP (Microcom Networking Protocol) is a data communications protocol developed by Microcom for full duplex, error-free communications over telephone lines. This protocol detects and corrects errors which can result from telephone line noise and other signal distortions. NOTE: MNP can only operate at speeds of 2400bps or higher. There are several levels of MNP operation available also referred to as service classes. The service class refers to the following techniques the modem uses to transfer data. The 14.4Kbps Modem supports classes 2, 3, 4, and 5 and these classes are summarized as follows: CLASS 2. Uses an asynchronous, byte-oriented format in which standard byte-framing techniques (start and stop bits) and full-duplex transmission are used. CLASS 3. Uses a synchronous, bit-oriented format in which standard byte-framing techniques are removed. This increases throughput by approximately 20%. CLASS 4. Optimizes performance by using more efficient framing techniques and allowing for transmission of large data blocks. Data block size is adjusted based on the quality of the telephone line (smaller for poor lines; larger for higher quality lines). This technique reduces the number of retransmissions and maximizes transfer rate based on the quality of the phone line. CLASS 5. Includes all the features of CLASS 4 and also features data compression. Both downloaded and interactive real-time data are compressed. A significant increase on most data throughput can be realized. The AT%C1 command enables this class. If MNP 5 is disabled, the Modem defaults to Class 4. MNP5 and MNP 4 are not compatible. 4.2 MNP Data Mode After establishing the MNP connection, the modem will perform all functions performed during normal data mode EXCEPT: (1) When retrains are performed. At 2400 bps operation or higher, the Modem may lose synchronization with the incoming line signal. Retraining is an adjustment process performed when one of the modems detects possible line problems which threaten data integrity. (2) When in the command mode following an escape sequence. The Modem will continue to acknowledge and accept data. This data is stored until the Modem is returned to data mode and then the data is delivered. In non-MNP mode, any data received while the Modem is in command mode is lost. Class 5 Data Compression. Class 5 may be enabled or disabled by using the AT%Cn command. During an MNP 5 connection, the Modem compresses data into tokens before transmitting to the remote modem, and de-compresses the data before it is received. Programmable Inactivity Timer. You can specify the length of time the modem will wait before disconnecting when no data is sent or received. In MNP mode, this timer is reset whenever data is sent or received. Use the AT\Tn command to set this value where N is a number between 0 and 42 minutes. Data Transfer. You may operate MNP in either block or stream mode. In stream mode, MNP sends data frames in varying lengths depending on the amount of time between characters being received. Stream mode is selected with the AT\Ln command. In block mode, MNP sends fixed data frames of 64, 128, 192, or 256 characters in length. Your communications software must support the use of block mode. 4.3 AT Commands for MNP Operation The 14.4K Modem supports all of the preceding classes. The following AT Commands apply to the MNP protocol: AT\An Maximum MNP Block Size AT\Bn Transmit Break AT\Gn Modem to Modem Flow Control A\Kn Break Control AT\Ln MNP Block Transfer Control AT\Nn Operation Mode Control AT\Wn Split Speed Operation AT\Z Switch to Normal Mode AT*H MNP Link Negotiation Speed Default selections are highlighted. Command: AT\An Maximum MNP Block Size. Use this command to transmit smaller blocks of data in a reliable data link connection. 0 = set maximum block size to 64 characters. 1 = set maximum block size to 128 characters. (DEFAULT) 2 = set maximum block size to 192 characters. 3 = set maximum block size to 256 characters. Command: AT\Bn Transmit Break. When this command is entered during a non-MNP connection, a break signal is sent to the remote modem. The length of the break is 100 times the n parameter (1-9) in milliseconds. The default is 3. Command: AT\Gn Modem to Modem Flow Control. Enables or disables modem to modem flow control during a normal mode connection. This command is ignored when error correction is selected. 0 = Disables flow control (XON/XOFF) (DEFAULT) 1 = Enables flow control (XON/XOFF) Command: AT\Kn Break Control. Determines the modem response when a BREAK is received from the DTE or the remote modem. The values of the parameters vary based on the three following conditions: (1) When a break is received from the DTE during NORMAL or MNP mode: 0, 2, 4 = modem enters command mode without sending a break to the remote modem. 1 = modem clears the terminal and modem buffers and sends a break to the remote modem. 3 = modem does not clear the buffers, but sends a break to the remote modem. 5 = modem sends a break to the remote modem in sequence with any transmitted data. (DEFAULT) (2) When a break is received from the remote modem during NORMAL mode: 0, 1 = modem clears the terminal and modem buffers and sends a break to the local DTE. 2, 3 = modem does not clear the buffers but sends a break to the local DTE. 4, 5 = modem sends a break in sequence with any data being buffered. (DEFAULT) (3) When a break is received from the DTE during DIRECT MODE: 0, 1, 3 = modem sends a break to the remote modem and enters command mode. 2, 4, 5 = modem sends a break to the remote modem. (DEFAULT) Command: AT\Ln MNP Block Transfer Control. Determines whether or not the modem will use block or stream mode for MNP link. 0 = uses stream mode for MNP link connections (DEFAULT) 1 = uses block mode for MNP connections Command: AT\Nn Error Correction Operating Mode. Selects the operating mode the modem uses while connected. 0 = NORMAL (speed buffering) mode. 1 = DIRECT (pass-through) mode. 2 = RELIABLE LINK mode. Specifies error correction for the modem-to-modem connection 3 = AUTO-RELIABLE LINK mode. Attempts error-correction connection but will fall back to normal mode if unable to establish an MNP link. 4 = LAPM error correction mode. 5 = MNP error correction mode Command: AT\Wn Split Speed Operation. Supports a split-speed DCE/DTE interface for applications which require a transmit speed of 75bps and receive speed of 1200bps at the DTE interface. 0 = disables (DEFAULT) 1 = enables Command: AT*H MNP Link Negotiation Speed. Controls the connection speed for link negotiations. 0 = link negotiation occurs at the highest supported speed. (DEFAULT) 1 = link negotiation occurs at 1200bps. 4.4 S-Register Values for MNP Operation The following S-Registers apply to the MNP protocol. S36 LAPM Failure Control S38 Delay Before Forced Connect S40 Bit-Mapped S46 Data Compression Control S95 Extended Result Codes S36 0-7 7 LAPM Failure Control Description: Indicates what happens during a LAPM failure. These fallback options take effect immediately upon connection if S28=148. If an invalid number is entered, the number is accepted into the register, but S36 acts as if the default value has been entered. 0 = modem disconnects 1 = modem stays online; establishes a direct mode connection. 2 = Reserved. 3 = modem stays online; establishes a normal mode connection. 4 = attempts MNP connection; if it fails, modem disconnects. 5 = attempts MNP connection; if it fails, establishes a direct mode connection. 6 = Reserved. 7 = attempts MNP connection; if it fails, establishes a normal mode connection. (DEFAULT) S38 0-255 20 Delay Before Forced Disconnect Description: This register specifies the delay between the modems receipt of the ATH command to disconnect. S40 Bit Mapped. Bit Mapped Registers (for MNP) Description: Indicates the status of command options. Bit 0 MNP Extended Services 0 = disabled (-K0) 1 = enabled (-K1) (DEFAULT) Bit 1 Power Level Adjustment for Cellular Use ()Mn) 0 = auto adjustment ()M0) (DEFAULT) 1 = force adjustment ()M1) Bit 2 MNP Link Negotiation Speed (*H1) 0 = highest speed (*H0) (DEFAULT) 1 = 1200 bps (*H1) Bits 3-5 Break Handling (\Kn) 0 = \K0 1 = \K1 2 = \K2 3 = \K3 4 = \K4 5 = \K5 (DEFAULT) Bits 6-7 MNP Block Size 0 = 64 chars. (\A0) 1 = 128 chars. (\A1) 2 = 192 chars. (\A2) (DEFAULT) 3 = 256 chars. (\A3) S46 136, 138 Data Compression Control 136 = error correction protocol with no compression 138 = error correction protocol with compression (DEFAULT) Description: Controls selection of compression. S95 none Extended Result Codes Bit 0 = CONNECT CODE indicates DCE speed instead of DTE speed. Bit 1 = Append /ARQ (automatic repeat request) to verbose CONNECT XXXX result code if protocol is other than none. Bit 2 = Enable CARRIER XXXX result code. Bit 3 = Enable PROTOCOL XXXX result code. Bit 5 = Enable COMPRESSION result code. Bits 4, 6, and 7 are reserved. Description: The bits in this register can be set to override some of the ATWn command options. Section Five: Error Correction: V.42/V.42bis 5.1 Introduction V.42 and V.42bis are two different communication protocol standards set by CCITT (Consultative Committee on International Telegraph and Telephone). V.42 is the CCITT standard for error correction in modems and is normally found in modems that are 2400bps or faster. V.42 supports LAPM and MNP 4 and is therefore compatible with modems using MNP 4. The V.42 specification is a standard that supports one of the Microcom MNP 2-4 error correction protocols or the LAPM error correction protocol. The V.42bis specification is a data compression standard that requires the LAPM error correction protocol, as well as providing data compression up to twice as fast as the MNP 5 data compression standard. MNP 5 is another data compression standard that requires the MNP 4 error correction protocol. It is not compatible with V.42bis and is slower than the V.42bis data compression standard. Detection. Immediately after the initial handshake , the communicating modems exchange a sequence of detection patterns to verify that both sides support the error correction technique. Negotiation. The communicating modems exchange configuration information. If the detection phase fails, or negotiation does not achieve the desired connection type, the modem can do one of the following: * hang up * fall back to MNP * fall back to a standard asynchronous mode In this case, you would use register S36 for Negotiation Fallback and/or S48 for Negotiation Action. Because MNP does not support a detection phase, you must select MNP 4 as a forced fallback with S36 and S48. The following S registers are used for V.42 LAPM operation: Register Description S36 V.42 Negotiation Fallback S38 Delay Before Forced Connect S41 Bit-Mapped Registers S46 Protocol Selection S48 V.42 Negotiation Action S82 Break Handling S86 Connection Failure Cause Code S95 Extended Results Code These registers are described in the balance of this section. 5.2 S Registers 5.2.1 V.42 Negotiation Fallback (S36) Register S36 specifies allows you to indicate what action to take when a desired connection cannot be made. The options are: S36=0 Modem hangs up. S36=1 Modem stays on-line and a direct mode connection is established. When running in direct mode, no flow control characters are recognized or transmitted. Flow control is when a receiving buffer tells the transmitting source to start and stop transmission. Direct mode is often used for compatibility with older style modems. S36=2 Reserved. S36=3 Modem stays on-line and a normal mode connection is established. Normal mode (or speed buffering) allows the modem to send and receive at a speed different from the speed of the physical, or modem to modem connection. S36=4 If S Register 48 is 128, an MNP connection is attempted; if it fails, the modem disconnects. S36=5 If S Register 48 is 128, an MNP connection is attempted; if it fails, a direct mode connection is established. S36=6 Reserved. S36=7 If S Register 48 is 128, an MNP connection is attempted; if it fails, a normal mode connection is established. (DEFAULT) 5.2.2 Delay Before Forced Connect (S38) S38 allows the following: S38 = 0-255 Specifies the delay between the modems receipt of the ATH command to disconnect (20 is the default). 5.2.3 Protocol Selection (S46) S46 allows the following: S46=136 Activates LAPM protocol with NO V.42bis compression. (DEFAULT) S46=138 Activates LAPM protocol WITH V.42bis compression. NOTE: In addition to V.42bis, the modem also implements MNP 5 data compression. V.42bis is used only with LAPM; MNP 5 is used only with MNP 4. 5.2.4 V.42 Negotiation Action (S48) Negotiation determines the capability of the remote modem. If the capabilities of the remote modem are known and negotiation is unnecessary, you can bypass this function. S48=7 Enables negotiation. (DEFAULT) S48=0 Disables negotiation. This bypasses the negotiation and detection phases and proceeds with LAPM. S48=128 Disables negotiation. This bypasses the negotiation and detection phases and proceeds at once with the fallback options specified in S Register 36. This option can be used to force MNP. 5.2.5 Bit-Mapped Registers These registers control compression selection, retraining, flow control, and block mode control. Bits 0,1 = Compression selection Bit 2 = Auto retrain Bit 3 = Modem to Modem Flow Control Bit 4 = Block Mode Control Bits 5-7 are reserved 5.2.6 Break Handling (S82) LAPM specifies three methods of break signal handling: * in sequence, expedited, or destructive S82=128 In sequence. Modem sends a break in sequence with any transmitted data; data integrity is maintained both ahead of and after the break. (DEFAULT) S82=3 Expedited. Modem sends a break immediately; data integrity is maintained both ahead of and after the break. S82=7 Destructive. Modem sends a break immediately; data being processed by each modem at the time of the break is destroyed. 5.2.7 Connection Failure Cause Code (S86) When the modem issues a NO CARRIER result code, a failure code is written to register S86. S86 records the first event that contributes to a NO CARRIER message. The result code definitions are as follows: S86=0 Normal disconnect; no error occurred. S86=4 Loss of carrier. S86=5 V.42 negotiation failed to detect an error correction modem at the other end. S86=9 The modems could not find a common protocol. S86=12 Normal disconnect initiated by remote modem. S86=13 Remote modem does not respond after 10 re-transmissions of the same message. S86=14 Protocol violation. 5.2.8 Extended Results Code (S95) You can set the bits in this register to override some of the ATWn command options. A bit to set to 1 in this register enables the corresponding result code regardless of the ATWn setting. Bit 0 = CONNECT result code indicates DCE speed instead of DTE speed. Bit 1 = Append/ARQ to verbose CONNECT XXXX result code if protocol is not NONE. Bit 2 = Enables CARRIER XXXX result code. Bit 3 = Enables PROTOCOL XXXX result code. Bit 5 = Enables COMPRESSION result code. Bits 4, 6, 7 are reserved. 5.3 AT Commands for Error Correction (V.42/V.42bis) The following AT commands apply to the V.42/V.42bis protocol: AT%Cn Compression Control AT%En Auto Retrain AT%Fn Split-Speed Direction Select AT%L Report Received Signal Level AT%Q Report Line Signal Quality Command: AT%Cn Compression Control. Determines whether or not modem will use data compression. 0 = disables data compression 1 = enables MNP5 data compression negotiation 2 = enables V42bis data compression 3 = enables both V.42bis and MNP5 data compression (DEFAULT) Command: AT%En Auto-retrain. Determines whether or not the modem automatically monitors the line quality and requests a retrain when necessary. 0 = disables line quality monitor auto-retrain (DEFAULT) 1 = enables line quality monitor auto-retrain 2 = enables line quality monitor auto retrain and auto fall back/forward. Command: AT%Fn Split-Speed Direction Select. Determines which direction (transmit or receive) has the 75bps channel and which has the 7500bps channel. Valid only if the \W1 command has been entered. 1 = selects 75Tx/1200Rx 2 = selects 1200Tx/75Rx (DEFAULT) Command: AT%L Report Received Signal Level. Possible values are: 009 = -9 dBm, 010 = -10dBm, etc. all the way to 043 (-43 dBm) Line signal and noise are determined by the unit of measurement dBm (decibel referenced to one milliwatt). To arrive at a signal/noise ratio, the noise level is subtracted from signal level in dBm. Command: AT%Q Report Line Signal Quality. Returns a high-order byte of the calculated EQM (eye quality monitor). This can range from 0 to 255. When the value is 8 or greater, the modem will automatically retrain if enabled by the AT%E1 command. The value for a normal connection ranges from 0 to 2 and approaches 8 for a progressively poorer connection. Returns an OK result code. 000 to 007 = no retrain 008 to 255 = retrain performed if enabled by %E1. Section Six: V.32/V.32bis Operation These CCITT protocols allow for high-speed data transmission and reception up to a maximum throughput speed of 57,600 bps (with V.42bis data compression). The 14.4Kbps modem is upwardly compatible to both of these high-speed modulation protocols. The V.32 CCITT standard enables full-duplex 9600 bps asynchronous transmission to occur synchronously over the switched telephone network and can attain throughput rates of 38,400 bps when combined with V.42 error control. The V.32bis modulation protocol extends the 9600 bps capability of V.32 to 14,400 bps while remaining compatible with V.32 modems. Possible modem to modem connection speeds are as follows: V.32 4800 bps 9600 bps V.32bis 14.4Kbps 12K bps 7200 bps The ATNn command (Modulation Handshake) determines whether or not the modem allows only particular connections, or automatically detects a remote modems desired connection. ATN1 (default) allows communicating at any speeds supported by both modems. Entering the command ATN0 requires that the speed of the connection be that specified by the value of S-Register 37 (see p. 53). If that value were not one supported by V.32, communication would not be possible. Section Seven: Diagnostics The 14.4Kbps modem includes several tests which evaluate the operation of the modem, its connection to the local DTE, and the communications link between the local and remote modems. Use of these tests requires setup of internal registers and may also require the use of two modems and a central office line simulator. A thorough knowledge of modem operation and registers is needed for their use. 7.1 Local Analog Loopback Test This test verifies the path between the local modem and the PC. 1. Set the DTE speed from 1200 to 14,400 bits per second. If the speed is less than 1200 or greater than 14,400 the test WILL NOT operate and a result code of ERROR will be generated if any tests are attempted. 2. Make sure the modem is in command mode (no connection made). 3. Issue an AT&Q0 command to the modem. This sets the modem to the direct mode. 4. Set the timer register (S18) for desired test time (in seconds). Example: ATS18=10 provides for a 10 second test. 5. To begin the test, type AT&T1 [ENTER]. The modem should respond with a CONNECT message. 6. After the number of seconds specified in S18, the modem will terminate the test and respond with OK. 7.2 Local Analog Loopback Test with Self-Test This test verifies the integrity of the local modems transmit and receive circuits. 1. Set the DTE speed from 1200 to 14,400 bits per second. If the speed is less than 1200 or greater than 14,400 the test WILL NOT operate and a result code of ERROR will be generated if any of the tests are attempted. 2. Make sure the modem is in command mode (no connection made). 3. Issue an AT&Q0 command to the modem. This sets the modem to the direct mode. 4. Set timer register (S18) for desired test time (in seconds). Example: ATS18=10 provides for a 10 second test. 5. To begin, type AT&T8 [ENTER]. The modem responds with OK. 6. After the number of seconds specified in S18, the modem should respond with 000 (meaning 0 errors were found during the self test). 7.3 Remote Digital Loopback Test 1. Set the DTE speed from 1200 to 14,400 Bits per second. If the speed is less than 1200 or greater than 14,400 the test WILL NOT operate and a result code of ERROR will be generated if the test is attempted. The baud rate is also limited to the highest baud rate supported by the telephone line (14,400 is possible if the telephone line is without distortion and noise free). If the telephone line has problems, bring the baud rate down to 9600 or 2400. If the line quality is too poor, use a line simulator to run this test. 2. Issue an AT&Q0 command to the local modem. This sets the modem to the direct mode. 3. Issue an AT&Q0 command to the remote modem, also setting it to the direct mode. 4. Issue an AT&T4 to the remote modem. This instructs the remote modem to grant a request for a remote digital loop back test. 5. Issue an ATS0=1 to the remote modem which allows it to auto-answer the incoming call. 6. Set the timer register (S18) of the local modem for desired test time (in seconds). Example: ATS18=10 provides for a 10 second test. 7. Issue a dial command to the local modem to instruct it to call the remote modem. Wait until the two modems have established a connection. 8. Type the escape sequence +++ to revert to command mode. The modem will respond with OK. 9. To start the test, type AT&T6 [ENTER]. The modem will return a CONNECT response if the loopback data link has been successfully completed, and an ERROR response if the link has failed. If a CONNECT response was received, key in a text message and it will echo on the screen. 7.4 Remote Digital Loopback Test with Self-test 1. Set the DTE speed from 1200 to 14,400 bits per second. If the speed is less than 1200 or greater than 14,400 the test WILL NOT operate and a result code of ERROR will be generated if the test is attempted. The baud rate is also limited to the highest baud rate supported by the telephone line (14,400 is possible if the telephone line is without distortion and noise free). If the telephone line has problems, bring the baud rate down to 9600 or 2400. If the line quality is too poor, use a line simulator to run this test. 2. Issue an AT&Q0 command to the local modem. This sets the modem to the direct mode. 3. Issue an AT&Q0 command to the remote modem, also setting it to the direct mode. 4. Issue an AT&T4 to the remote modem. This instructs the remote modem to grant a request for a remote digital loop-back test with self test. 5. Issue an ATS0=1 to allow the remote modem to auto-answer the incoming call. 6. Set timer register (S18) of the local modem for desired test time (in seconds). Example: ATS18=10 provides for a 10 second test. 7. Issue a dial command to the local modem to instruct it to call the remote modem. Wait until the two modems have established a connection. 8. Type the escape sequence (+++) to revert to the command mode. The modem will respond with OK. 9. Type AT&T7 [ENTER] to initiate the remote digital loopback test. The local modem will send a test pattern to the remote modem. This pattern will not be visible on the screen. 10. The modem will then send a three-digit value, indicating the number of errors detected during testing. If the result is 000, no errors were found. Section Eight: Troubleshooting This section lists the most common problems that may be encountered and their possible solutions. SYMPTOM: POSSIBLE REMEDY: No dial tone. Check the following: Verify that you have the cables plugged in correctly as instructed in Section One. Connect a telephone set directly to the wall jack and check for dial tone. If no dial tone is heard, the telephone line is not working. Contact the telephone company. No response when you type in AT commands. Check the following: There may be a conflicting port address. Re-configure the modem COM address. (INTERNAL ONLY) Verify that the communication software is set for the same COM address. Your RS-232 cable connection (EXTERNAL ONLY). AT commands are not visible. Check the following: Make sure the echo command is set to off. Change to echo with the ATE1 command. After data connection is established, data is displayed as garbled characters. Check the following: Make sure the local and remote modem configurations are compatible. Verify that both modems are operating with the same settings, speed, data, parity, and stop bits. The software may not be set for correct terminal emulation. Configure software to correct type. ANSI terminal emulation is most commonly used. Turn off your modem (EXTERNAL), exit, and re-run your communications software. Power down your system (INTERNAL) and re-run your communications software. A slowdown is noticed when running multi- tasking software. When multi-tasking with fast machines (e.g., 386DXs, 486/DXs), the CPU will easily handle a high number of interrupts. With slower CPUs such as 286 and 386SX machines, a slowdown can occur. Appendix A: How to Set Bit-Mapped Registers To set or change bit-mapped registers requires a sound working knowledge of binary notation and should not be undertaken casually. Bit-mapped S-Register values are calculated as follows. Each bit (0-7) has a corresponding decimal value as shown below. Of the bit is ON, it has that corresponding value; if the bit is OFF, its value is zero. Bit Decimal 0 1 1 2 2 4 3 8 4 16 5 32 6 64 7 128 Some bit-mapped registers combine bits which make calculating values even more complex. Example: if bits 3 and 4 were combined to offer four options ((0-3), the value would be calculated this way: BIT 4 (16) BIT 3 (8) OPTION VALUE 0 (0) 0 (0) 0 0 0 (16) 1 (8) 1 24 (16+8) 1 (32) 0 (16) 2 48 (32+16) 1 (48) 1 (24) 3 72 (48+24) Now, let's try a real example. Register S14 contains a set of bit-mapped registers for echoing commands, result code display, word/number responses, dial method, and answer/originate operation. On the next page are the default settings and corresponding values along with default settings. Value(Bit) 128(7) 64(6) 32(5) 16(4) 8(3) 4(2) 2(1) 1(0) value | | | | | | | |____ ignored 0 | | | | | | |_________ 0= no echo | | | | | | 1= echo 2 | | | | | |______________ 0= send resp. | | | | | 1= no send 0 | | | | |___________________ 0= send # | | | | 1= send word 8 | | | |________________________ reserved 0 | | |_____________________________ 0= touch tone 0 | | 1= pulse | |__________________________________ reserved 0 |_______________________________________ 0= answer 1= originate 128 The S-Register bit-mapped value would be 138 (2+8+128) Appendix B: Technical Specifications Modem Data Rate: 14.4K, 12K, 9600, 7200, 4800, 2400, 1200, or 300 bps Fax Data Rate: 14.4K, 9600, 7200, 4800, 2400 bps. Compatibility: Modem Modulation Protocols CCITT: Bell 103, 212A V.32bis, V.32, V.42bis, V.42, V.22, and V.21. Fax Modulation Protocols CCITT: V.17, V.29, V.27 ter, and V.21 Operation: Asynchronous operation (MNP 3: synchronous) Automatic format and/or speed sensing. Tone or Pulse dialing Programmable speaker volume control--recognizes busy signal, ringing, no answer, and no dial-tone status. Diagnostics: Local/remote digital and analog loopback. Automatic power-on self-test. Physical and Electrical Characteristics Size: 8" x 4 3/8" (INTERNAL); 5 1/2" x 5" x 2" (EXTERNAL) Power: 500 mA@ 5V(INTERNAL); 120V AC@ 100mA (EXTERNAL) 8- or 16-bit interface (INTERNAL) 2 RJ-11 modular phone connectors. RS-232 serial cable (EXTERNAL) Compatible with IBM PC systems (ISA and EISA). Appendix C: Compliance Information FCC Statement "This device complies with part 15 of the FCC rules. Operation is subject to the following two conditions: (1) This device may not cause harmful interference. (2) This device must accept any interference received including interference that may cause undesired operation. THIS UNIT COMPLIES WITH FCC PART 68 AS OF DATE OF MANUFACTURE. This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to Part 15 of FCC rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generates, uses, and can radiate radio frequency energy and, if not installed in accordance with the instructions, may cause harmful interference to radio communications. However, there is no guarantee that interference will not occur in a particular installation. If this equipment does cause harmful interference to radio or television reception, which can be determined by turning the equipment off and on, the user is encouraged to try to correct the interference by one or more of the following measures: * Re-orient or relocate the receiving antennae. * Increase the separation between the equipment and the 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. Note: This unit was tested with shielded cables on the peripheral devices. Shielded cables must be used with the unit to insure compliance. Note: The manufacturer is not responsible for any radio or TV interference caused by unauthorized modifications to this equipment. Such modifications could void the user's authority to operate the equipment." Notification to the Telephone Company Notification to the telephone company is no longer required prior to connecting the registered equipment but upon request from the telephone company the user shall tell the telephone company which line the equipment is connected to as well as the registration number and the ringer equivalence of the registered protective circuitry. In most, but not all areas, the sum of all RENs should be 5.0 or less. The FCC Registration number and Ringer Equivalence number are printed on the main chip in the center of the internal modem board, or on the underside of the external modem. Malfunction of the Equipment In the event that the MODEM should fail to operate properly, the customer shall disconnect the equipment from the telephone line to determine if it is the customer's equipment which is not working properly, or if the problem is with the MODEM, the user shall discontinue use until it is repaired. In the event service is needed the user should contact the vendor from whom you purchased the MODEM. Telephone Connection Requirements Except for telephone company-provided ringers, all connections to the telephone network shall be made through standard plugs and standard telephone company-provided jacks, or equivalent, in such a manner as to allow for easy and immediate disconnection of the terminal equipment. Standard jacks shall also be arranged that, if the plug connected thereto is withdrawn, no interference to the operation of the equipment at the customer's premises which remains connected to the telephone network, shall occur by reason of such withdrawal. Incidence of Harm Should terminal equipment or protective circuitry cause harm to the telephone network, the telephone company shall, where practical, notify the customer that temporary discontinuance of service may be required; however, where prior notices are not practical, the telephone company may temporarily discontinue service if such action is deemed reasonable in the circumstances. In the case of such temporary discontinuance, the telephone company shall promptly notify customers and will be given the right to bring a complaint to the FCC if they feel the disconnection is not warranted. Changes in Telephone Company Equipment or Facilities The telephone company may make changes in its communications facilities, equipment, operations, or procedures, where such action is reasonably required and proper in its business. Should any such changes render the customer's terminal equipment incompatible with the telephone company facilities, the customer shall be given adequate notice to make modifications to maintain uninterrupted service. General The FCC prohibits customer-provided terminal equipment be connected to party lines or to be used in conjunction with coin telephone service. Installation The MODEM is equipped with a USOC RJ-11 standard miniature modular jack and is designed to plug directly into a modular jack. DOC Compliance Statement (Canada) 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. Before installing this equipment, users should ensure that it is permissible to be connected to the facilities of the local telecommunications company. The equipment must also be installed using an acceptable method of connection. In some cases, the company's inside wiring associated with a single line individual service 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 the user to this equipment, or equipment malfunction, may give the telecommunications company cause to request the user to disconnect the equipment. Users should ensure, for their own protection, that the electrical ground connections of the power utility, telephone lines, and internal metallic water pipe system, if present, are connected together. This precaution may be particularly important in rural areas. CAUTION Users should not attempt to make such connections themselves, but should contact the appropriate electric inspection authority or electrician, as appropriate. The Load Number (LN) assigned to each terminal device denotes the percentage of the total load to be connected to a telephone loop which is used by the device to prevent overloading. The termination on a loop may consist of any combination of devices subject only to the requirement that the total of the load numbers of all the devices does not exceed 100. The Load number appears on either the lower inside portion of the modem's metal bracket (internal) or on the underside of the external modem. Glossary of Modem Terminology A ALGORITHM. A formula or procedure which employs various methods defining how data is to be used to give a prescribed result. ANALOG SIGNAL. Signals which can vary over a continuous range (e.g., the human voice over conventional telephone lines). Analog circuitry is more subject to distortion and noise, but it is more capable of handling complex signals than are digital signals which can have only discrete values. ARQ. Automatic ReQuest for retransmission. A type of communications link where the receiver asks the transmitter to re-send a block of data when errors are detected. ANSI. American National Standards Institute. A non-profit, private industry association which governs most USA-standards setting agencies. ASCII. Acronym for American Standard Code for Information Interchange. ASCII is an ANSI character set. The standard ASCII character set consists of 128 decimal numbers (0-127) for letters of the alphabet, numerals, punctuation marks, and common special characters. The extended ASCII character set extends to 255 characters and contains special mathematical, graphics, and foreign characters. ASYNCHRONOUS COMMUNICATION. A method of transmission in which data is sent one character is sent one bit at a time; also referred to as serial transmission. B BELL STANDARDS. Refers to the domestic modulation protocol standards developed by the former AT&T Bell Systems such as Bell 103 (300bps transmission) and Bell 212A (1200bps transmission). BIT-MAPPED REGISTERS. An S-register which contains multiple bit-oriented values. Example: the value of S22 is the sum of the bit values which you select (bits 0-1: speaker volume/value: 0-3; bits 2-3: speaker control/value: 0-3; bits 4-6: limit result codes/value: 0, 4-6, 7). BLIND DIALING. An automated process whereby the modem goes off-hook and dials without waiting for a dial tone. This is prohibited in many countries. BLOCK TRANSFER CONTROL. Determines whether or not the modem uses block or stream mode during an MNP connection. In stream mode, MNP sends data frames in varying length. Block mode sends fixed data frames of 256 characters and is selected with the MNP-based \L command. BREAK HANDLING. Determines how the modem responds when a BREAK signal is received from either the DTE (Data Terminal Equipment or computer/terminal) or the remote modem. This is controlled by the MNP-based AT extended command \K. A break signal is represented on the communications line by a steady space signal for a significant length of time. Break signals may be activated from the keyboard by pressing the BREAK key or the control (CTRL) and C keys. C CCITT. Consultative Committee for International Telephone and Telegraph. This advisory organization is part of the ITU (International Telecommunication Union) which is an agency of the United Nations. COMMAND MODE. The modem is in command mode when it is turned on or reset, when it loses its connection to a remote modem, when it is in on-line mode, or when escape characters (+++) are typed. To transmit data, the modem must be in data mode. The modem does not transmit data when in command mode. COMMUNICATIONS PROTOCOL. A set of procedures which controls how a data communications network operates. D DCD. Data Carrier Detect. Indicates to the terminal device that the modem is receiving a valid carrier signal from a remote modem. The carrier is a tone at a specified frequency. DCE. Data Communications Equipment. The local and/or remote modem. A DCE is usually connected to a DTE. DTE. Data Terminal Equipment. The computer or terminal, either local (yours), or the remote (the one you're communicating with). A DTE is usually connected to a DCE. DTR. Data Terminal Ready. The computer issues this signal to the attached modem indicating that it is ready to receive data. DATA COMPRESSION. A technique that examines transmitted data for redundancy and replaces strings (groups) of characters with special codes which the receiving modem interprets and restores to its original form. Transmission of compressed data results in shorter connect times and hence cost savings for connect charges. Data compression is sometimes called source encoding. DATA MODE. The modem is in data mode when a connection has been established with a remote modem and sends a CONNECT response confirming the connection. User data may then be transmitted or received. DIAL MODIFIER. Dial modifiers are special characters appended to the ATD command which instruct the modem how to place a call. DIGITAL SIGNAL. A discrete signal which can only take on one of several (usually only two) discrete levels in contrast to analog signals which can take a continuous range of levels. E ERROR DETECTION AND CORRECTION. The transmitting modem attaches a special pattern (called a frame check sequence) calculated according to a prescribed algorithm from user-defined data to the end of a block of data. The receiving modem performs the same algorithm and compares it to the one with the transmitted data. If these match, then the block of data has been received correctly. If not, the block of data is re-transmitted until no errors are detected. ESCAPE SEQUENCE. Also referred to as the escape command. This special command is entered as three plus symbols (+++) and places the modem in command mode and interrupts user data transmission, but does not terminate the data connection. This allows the entering of commands while the connection is maintained. EXTENDED AT-COMMAND. Extended commands were developed to provide greater functionality and control over modem operations than is available from the basic AT command set. F FAX MODE. The modem is in fax mode when, through use of fax communications software, it can send and receive faxes, print and display fax files, convert files to fax-files, and set certain fax-related features. Note: the modulation protocol used by the modem in fax mode is also different from the usual data mode modulation. FLOW CONTROL. Compensates for the difference between the rate at which data reaches a device and the rate at which the device processes and transmits. This is controlled by the extended AT command &K. The two common types of flow control are RTS/CTS signaling (a hardware based method, employing an electrical signal) and XON/XOFF (a software-based method using standard ASCII control characters to pause or resume transmission). FULL-DUPLEX. Two-way simultaneous transmission between modems, which may occur via a four-wire circuit on a leased line, or with a two-wire connection when the frequency bandwidth is divided into two distinct channels, or when echo cancellation is employed (e.g., Bell 103, 212, and V.22 use frequency division, while V.32 uses echo cancellation. G GUARD TONE. Guard tones are used in the United Kingdom and other countries. This requires that the modem transmit an 1800-Hz tone after it sends an answer tone. The guard tone is controlled by the &G command. Guard tones are not used in the U.S.A. H HALF-DUPLEX. Signal flow in both directions, but only one way at a time with each modem alternating between send and receive. HAYES-COMPATIBLE. Hayes Microcomputer Products, Inc. developed the AT command set which has become a de facto industry standard. Hayes commands are always initiated with an AT (attention code) prefix. HOOK FLASH. The dial modifier ! causes the modem to go on-hook (hang-up) for one-half second. Also controlled by the ATH command. L LAPM. Link Access Protocol Modem. A V.42 ARQ type of error correction protocol which is controlled by S-Register 46, where LAPM may be activated with or without V.42bis data compression. LEASED LINE. Also referred to as a private line. A leased line is obtained from a communications company (carrier) to provide a transmission medium between two points. The line consists of a permanent dedicated circuit between two points, or to set of previously arranged points. The cost of the line is usually based on the distance between locations. This is in contrast to switched or dial-up lines, which can be connected to any point on the network. LINE MODULATION. The means by which a carrier is varied to represent a signal carrying information. In a modem, the users digital data is used to modulate the modem's transmitters carrier or carrier to allow the digital signal to be carried over analog facilities. LONG SPACE DISCONNECT. Determines whether or not modem disconnects when it receives a continuous break from a remote modem. Controlled by the ATY command. LOOPBACK TESTS. There are four types of loopback tests which are as follows: (1) the local digital loopback tests the operation of the DTE, including whether or not data is leaving the terminal or computer port; (2) the local analog loopback tests the digital and analog circuits of the modem; (3) the remote digital loopback checks the operating condition of the line and remote modem; (4) the remote analog loopback tests the line to the remote modem. M MNP. Microcom Networking Protocol. A series of data communications protocols developed by Microcom for full-duplex, error-free communications. MAKE/BREAK RATIO. The &P command controls the ratio of the off-hook (make) to on-hook (break) interval used by the modem when it pulse dials. &P0 selects a 39%/61% make/break ratio for use in the U.S. &P1 selects a 33%/67% make/break ratio for use in the United Kingdom and Hong Kong. MODULATION HANDSHAKE. Also referred to as Automode Enable and is controlled by the ATN command. This determines whether or not the modem must connect at a particular speed, or allow connection at any speed supported by both modems. N NEGOTIATION FALLBACK. Controlled by S-Register 36 as part of the V.42 protocol. Setting this register indicates what action to take when a desired connection cannot be made (e.g., hang-up, direct mode connect, normal mode connect). NON-VOLATILE RAM. Also NVRAM. Random access memory whose data is retained when power is turned off. This is especially useful for modems to store user-defined default configuration settings. These settings would be loaded into modem RAM at power-up. O ON-LINE STATE. Same as data mode. To transmit or receive data, the modem must be in the on-line state. When placing a call, the modem is put on-line with the dial command. P PBX. Private Branch Exchange. A telephone switch at a customer site. PULSE DIALING. Also referred to as rotary dialing, i.e., dialing with the older-style rotary dial wheel. The dial modifier ATP sets the modem to pulse dialing, which is the default method as opposed to tone dialing (push-button touch-tone) which is enabled with ATT. All telephone exchanges will accept older-style pulse dialing and most exchanges will accept modern tone-dialing. Tone dialing is faster and more reliable since mechanical relays and their inherent failure mechanisms are avoided. R RESULT CODE. A response sent by the modem after executing a command. The response reports the modems status or the progress of a call and can take the form of either digits (numeric) or words (verbose). Issuing a V1 command enables word responses. A V0 (V-zero) command enables numeric responses. The Q1 command disables their use entirely. Example: OK (word), or 0 (numeric) indicates that the modem successfully executed a command. RETRAIN. An adjustment process performed when one of the modems detects signal distortion or line noise which threaten data integrity. RTS/CTS. Request to Send/Clear to Send. RTS and CTS are two control signal lines between the modem (DCE) and terminal (DTE) which allow the terminal to control the flow of information. See also flow control. S SLEEP INACTIVITY TIMER. Determines the length of time the modem operates in normal mode with no activity before entering low-power sleep mode. SPLIT-SPEED DIRECTION. Determines which direction (transmit or receive) has the 75bps channel and which has the 1200bps channel, but is only active if the \W command is set to 1. Used with V.23 modulation only. STANDARD AT-COMMAND. The basic AT command set, originated by Hayes Microcomputer Products, Inc. SYNCHRONOUS CLOCK SOURCE. Applies to synchronous modem operations and is set with the &X command. The command specifies the clocking source referred to as the transmit signal element timing. This can be controlled by either the modem or the terminal. SYNCHRONOUS COMMUNICATIONS. A method of transmission in which data bits are sent continuously at the same rate under the control of a fixed frequency clock signal. T TOUCH-TONE DIALING. Push-button tone dialing as used on contemporary phone sets. The dial modifier ATT sets the modem to tone mode. Tone dialing is faster and more reliable than older-style pulse dialing. X XON/XOFF. XON and XOFF are the names of two different control characters. See also flow control. Acknowledgements The Complete Modem Reference. Gilbert Held. John Wiley & Sons, Inc. 1991. Upgrading and Repairing PCs. (Second Edition). Que Corporation. 1992.