1.1 Introduction Welcome to the world of data communications. You have acquired one of the finest intelligent desktop data/fax modems available today, model MT1432BA, from Multi-Tech Systems. Your MT1432BA modem provides data communication at 14,400-9600 bps (V.32bis/V.32), as well other prevalent datacomm standards. The MT1432BA also includes adaptive protocol enhancing used in typical Unixr batch file transfers and support for IBM's AS/400TM and System3xTM environment. This Owner's Manual will help you install, configure, test and use your MT1432BA data/fax modem. 1.2 How To Use This Manual This manual is divided into nine chapters. There are also several appendices at the end of this manual, most of which repeat information contained in the chapters, but in a more condensed form. These appendices can be used as a quick reference. The information contained in each chapter and appendix is as follows: Chapter 1 - Introduction and Description This chapter begins with a short introduction, followed by a guide (which you are now reading) to the use of this manual. There is a discussion about what components you can expect to be in the MT1432BA package. We then provide a more detailed description of the modem, as well as the modem's technical specifications. Chapter 1 includes sections covering power, LED indicators and a brief summary of PC board controls. (Chapter 8 covers switch settings more thoroughly.) Chapter 2 - Installation and Connection This chapter covers the information for connecting the MT1432BA to your terminal/computer and the phone lines and also which RS232C circuits are used. Chapter 2 explains how to install your MT1432BA modem to the point of operation. You will also find an illustration showing the modem's back-panel connectors. Chapter 3 - Manual Dial and Automatic Answer This chapter covers some modem operations, but delays discussion of Command mode operation until Chapter 4. This chapter covers Manual Dial mode, and Answer mode operation in detail, as well as the handshaking procedures employed between two modems in an auto-answer application. There is also some discussion of various ways of how to terminate a call. Chapter 4 - AT Command Mode Operation This may be the most important chapter of this manual. It begins with an introduction and discussion of the MT1432BA Command Mode fundamentals. A flow chart is provided to illustrate Command Mode and On- Line Mode operation and the methods used in each mode. Next, there is a summary of the modem's commands and responses. We then go into a detailed explanation of each MT1432BA command, providing examples where applicable. Chapter 5 - S-Registers This chapter covers the MT1432BA's S-Registers, which are used to store and/or configure various modem options. All of the S-Registers are charted and explained, followed by instructions on accessing the S- Registers and reading or changing their values. Chapter 6 - Callback and Remote Configuration This chapter covers how the MT1432BA's Callback and Remote Configuration features operate. This Chapter describes the usage of LOGIN Passwords, Set-Up Passwords and Remote Escape Characters as network management tools. Chapter 7 - Testing Your Modem This Chapter covers the modem's built-in test features. These are: Power-on Self Test, Local Analog Loopback, Digital Loopback and Remote Digital Loopback Tests. We have included a description of each test and how to use each test procedure. Chapter 8 - DIP-Switches and Jumpers The MT1432BA printed-circuit board options are covered in this chapter. Sixteen DIP-Switch settings, several berg jumpers,and the modem's speaker volume control are explained in detail, including all default settings. Chapter 9 - Service, Warranty, Technical Support & BBS Chapter 9 provides instructions for getting modems serviced at the factory, statements on your five-year warranty and information about our user Bulletin Board Service (BBS). Appendix A - ASCII/HEX/Decimal Conversion Chart (not in this text version) Appendix B - Pulse Dial and Tone-Dial Frequencies Appendix C - AT Command Summary Appendix D - DIP Switch Summary Appendix E - S-Register Summary Appendix F - Result Code Summary Appendix G - V.25bis Operation Appendix H - MT1432BA Cables Appendix I - RS232 Interface Specifications Appendix J- Multi-Tech Systems' Escape Methods 1.3 What is in Your Modem Package? Your MT1432BA is made up of many components. Make sure you have them all before trying to operate your modem. Your package should include: ù MT1432BA data/fax modem (Figure 1-1) ù RJ11 telephone cord ù AC Power Transformer ù This MT1432BA Owner's Manual If any of these items are missing, please contact Multi-Tech Systems, or your dealer/distributor. Figure 1-1. The MT1432BA Modem 1.4 Description Your MT1432BA modem is designed according to the international CCITT V.32bis specification for data signalling rates as high as 14400 bps full-duplex mode connections on Public Switched Telephone Networks (dial-up/2-wire lines). The MT1432BA also supports CCITT V.17 Group 3/EIA TR-29 Class 2 fax operation. This enables the modem to send and receive text, graphics and images to and from any Group 3 fax machine. The MT1432BA is downward compatible at speeds as low as 300 bps. This means the MT1432BA communicates with other vendor's V.32bis compatible modems, which insures your modem against obsolescence. The modem's reliable full duplex performance at high speeds over dial- up/2-wire lines is made possible through the latest trellis coding, echo cancellation, and automatic adaptive equalization techniques, and its VLSI technology makes the MT1432BA both small and affordable. The MT1432BA is AT command set compatible and incorporates a number of capabilities beyond the basics of V.32bis operation. Other capabilities include CCITT V.25bis standard for synchronous/asynchronous dialing, compatibility with CCITT V.42 error correction and V.42bis data compression in which data communication speeds can approach 57,600 bps (depending on the file content and the receiving modem's capability) and the data sent will be 100% error free. V.42 error correction incorporates both MNP Classes 3, 4 and LAPM. Data compression can be V.42bis for 4 to 1 throughput improvement or the popular MNP Class 5 for 2 to 1 throughput (depending on file content). The MT1432BA offers interactive automatic dialing capability, as well as Command mode option configuration. Up to ten command line/telephone numbers, of up to 60 digits each, can be stored in the modem's non-volatile memory. The modem uses pulse and/or tone dialing methods, and has the ability to recognize dial tones and busy signals for reliable call-progress detection; and the MT1432BA has the capability to detect AT&T "call card" tones for the purpose of accessing the user's calling card before an on-line connection is made. The MT1432BA is FCC-Registered for connection to the telephone networks. No Data Access Arrangements (DAA's) are required. Callback Security provides MT1432BA users with a new means of protecting their networks from unauthorized users. By use of the modem's automatic login routines and phone number/password directory, host sites can, after receiving a call, "callback to" a remote site at a predetermined number. This feature can also be used to reduce phone line costs for users through host site call origination. Remote Configuration gives users network management capability. Users can configure modems at remote sites from local modems, without having to visit the sites or rely on users to follow instructions. 1.5 FCC Regulations for Telephone Line Interconnection 1. This equipment complies with Part 68 of the Federal Communications Commission (FCC) rules. On the outside surface of this equipment is a label that contains, among other information, the FCC registration number and ringer equivalence number (REN). If requested, this information must be provided to the telephone company. 2. A suitable jack (Universal Service Order Code connecting arrangement) for this equipment is needed (see section 2.3). If applicable, the facility interface codes (FIC) and service order codes (SOC) are required. 3. The ringer equivalence number (REN) is used to determine the quantity of devices which may be connected to the telephone line. Excessive REN's on the telephone line may result in the devices not ringing in response to an incoming call. In most, but not all areas, the sum of the REN's should not exceed five (5.0). To be certain of the number of devices that may be connected to the line, as determined by the total REN's, contact the telephone company to determine the maximum REN for the calling area. 4. If this equipment causes harm to the telephone network, the telephone company will notify you in advance. But if advance notice isn't practical, the telephone company will notify the customer as soon as possible. Also, you will be advised of your right to file a complaint with the FCC if you believe it is necessary. 5. The telephone company may make changes in its facilities, equipment, operations, or procedures that could affect the operation of the equipment. If this happens, the telephone company will provide advance notice in order for you to make necessary modifications in order to maintain uninterrupted service. 6. If trouble is experienced with this equipment (the model of which is indicated below) please contact Multi-Tech Systems, Inc. at the address shown below for details of how to have repairs made. If the trouble is causing harm to the telephone network, the telephone company may request you remove the equipment from the network until the problem is resolved. 7. No repairs are to be made by you. Repairs are to be made only by Multi-Tech Systems or its licensees. Unauthorized repairs void registration and warranty. 8. This equipment cannot be used on public coin service provided by the telephone company. Connection to Party Line Service is subject to state tariffs. (Contact the state public utility commission, public service commission or corporation commission for information.) 9. If so required, this equipment is hearing-aid compatible. Manufacturer: Multi-Tech Systems, Inc. Trade Name: MultiModemIITM Model Number: MT1432BA FCC Registration #: AU7USA-65636- MD-E Ringer Equivalence: 0.5B Modular Jack (USOC) RJ11C or RJ11W (single line) Service Center in USA: Multi-Tech Systems Inc. 2205 Woodale Drive Mounds View, MN 55112 Voice (612) 785-3500 FAX (612) 785-9874 1.6 Canadian Limitations Notice Notice: The Canadian Department of Communications (DOC) label identifies certificated 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 malfunctions, 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 for this product is 5. This digital apparatus does not exceed the Class B limits for radio noise for digital apparatus set out in Department of Communications. 1.7 Technical Specifications Your MT1432BA data/fax modem meets the specifications listed below: Tradename MultiModemIITM Model Numbers MT1432BA, MT1432BAI, MT1432BA-MAC Data Rates (modem) 14,400, 9600, 4800, 2400, 1200, 0-300 bps Data Rates (fax) 14,400, 9600, 4800 bps Data Format Serial, binary, asynchronous at 0-300, 1200, 2400, 4800, 9600 bps; synchronous at 1200, 2400, 4800, 9600 bps Compatibility CCITT V.42bis, V.42, V.32bis, V.32, V.21*, V.22bis, V.22, V.23*,V.25bis, Bell 212A and 103/113, CCITT Group 3 T.4, T.30 and EIA TR-29 Class 2 (*V.21/V.23 Int'l models only) Error Correction V.42 (LAP-M or MNP 3 & 4) error correction Data Compression V.42 bis, (4:1 throughput) or MNP 5 (2:1 throughput) data compression Speed Conversion Serial port data rates adjustable to 300, 1200, 2400, 4800, 9600, 19,200, 38,400 and 57,600 bps Flow Control Xon/Xoff, Hardware RTS/CTS, ENQ/ACK, Options Unix-to- Unix Copy Protocol (UUCP) "Spoofing" Mode of Operation Half or Full duplex over both dial-up lines and 2-wire leased lines; automatic or manual dialing, automatic or manual answer Intelligent Features Fully "AT command" compatible, microprocessor controlled remote configuration, autodial, redial, repeat dial, dial linking, pulse or tone dial, dial pauses, call status display, auto-parity and data rate selection, keyboard-controlled modem options, non-volatile memory and on-screen displays for modem option parameters and up to ten telephone numbers/ command lines of up to 60 digits each, help menus Command Buffer 60 characters Modulation Trellis Coded Modulation (TCM) at 14,400, 12,000, 9600 bps, Quadrature Amplitude Modulation (QAM) at 9600 (non-trellis), 4800 and 2400 bps, PSK at 1200 bps, FSK at 300 bps Fax Modulations V.21CH2 FSK at 300 bps V.27ter DPSK at 4800 and 2400 bps V.29 QAM at 9600 and 7200 bps V.17 TCM at 14400, 12000, 9600, and 7200 bps Fax Carrier V.21CH2 (Half Duplex) Frequencies 1650Hz Mark, 1850Hz Space for Transmit Originate 1650Hz Mark, 1850Hz Space for Transmit Answer V.27ter 1800Hz Originate/Answer V.29 QAM 1700Hz Originate/Answer V.17 TCM 1800Hz Originate/Answer Carrier Frequencies 1800 Hz V.32bis/V.32 14.4K/12K/9.6K/4.8K Carrier Frequencies Transmit Originate: 1200 Hz 2400 & 1200 bps Transmit Answer: 2400 Hz (V.22bis/V.22 or Receive Originate:2400 Hz Bell 212A Standard) Receive Answer: 1200 Hz Carrier Frequencies, 1270 Hz Mark, 1070 Hz Space for 300 bps Transmit Originate (Bell Standard) 2225 Hz Mark, 2025 Hz Space for Receive Originate 2225 Hz Mark, 2025 Hz Space for Transmit Answer 1270 Hz Mark, 1070 Hz Space for Receive Answer Carrier Frequencies 980 Hz Mark, 1180 Hz Space for V.21 Transmit Originate 1650 Hz Mark, 1850 Hz Space for Transmit Answer 1650 Hz Mark,1850 Hz Space for Receive Originate 980 Hz Mark, 1180 Hz Space for Receive Answer V.23 390 Hz Mark, 450 Hz Space for Transmit Originate 1300 Hz Mark, 2100 Hz Space for Transmit Answer 1300 Hz Mark, 2100 Hz Space for Receive Originate 390 Hz Mark, 450 Hz Space for Receive Answer Transmit Level -10dBm (dial-up), 0 dBm (leased-line); dBm level selectable with DIP-Switch #3 in leased line setting Frequency Stability ñ0.01% Receiver Sensitivity -43 dBm under worst case conditions AGC Dynamic 43 dB Range Interface EIA RS232C/CCITT V.24 Connectors One DB25 RS232C connector; two RJ11 for phone line and telephone set; power Diagnostics Power-on Self Test, Local Analog Loop, Local Digital Loop, Remote Digital Loop. Indicators LEDs for Transmit Data, Receive Data, Carrier Detect, 14,400 bps, 9600 bps, 4800 bps, 2400 bps, 1200 bps, Off Hook, Terminal Ready, Error Correction and Fax Controls Toggle switches for Voice/Data with Originate or Answer, Power On/Off; Option Jumpers and DIP Switches for various modem options. Speaker Speaker for call progress monitoring Operating 0ø to 50ø C (32ø to 120ø F) Temperature Power 115 Volts AC, 60Hz, 0.3amp (2-prong outlet- Requirements mounted transformer) 240V/50Hz optional (International). Dimensions 6.150" x 9.00" x 1.375" 15.6 cm x 22.9 cm x 3.5 cm Weight 1.6 pounds/0.72 Kg (without transformer) 2.6 pounds/1.18Kg (with transformer) Limited Warranty Five Years 1.8 Power Power is supplied through an AC power transformer terminated with a standard two-prong plug. The transformer supplies low voltage AC to the modem, and plugs into any conventional 115 volt AC, 60 Hz, two-prong power outlet. The power transformer supplied with the modem is the only one that should be used. Use of any other transformer could cause damage to the modem. A Power On/Off switch is located on the back of the modem. 1.9 Modem LED Indicators The MT1432BA has twelve diagnostic LED indicators. They are: 1) Transmit (Send) Data (SD). This LED blinks when data is being transmitted, on for a space, off for a mark. The state of this LED matches the TD circuit on Pin 2 of the RS232C/V.24 interface. 2) Receive Data (RD). This LED blinks when data is being received, on for a space, off for a mark. The state of this LED matches that of the RD circuit on Pin 3 of the RS232C/V.24 interface. 3) Carrier Detect (CD). This LED is lit when a valid carrier tone has been detected. 4) 14400 bps (14.4). This LED is lit when the modem is connected at 14400 bps. Note: if the modem falls back to 12000 bps while in V.32bis mode, both 14.4 and 96 LEDs light. 5) 9600 bps (96). This LED is lit when the modem is set for 9600 bps operation. 6) 4800 bps (48). This LED is lit when the modem is connected at 4800 bps. 7) 2400 bps (24). This LED is lit when the modem is connected at 2400 bps. 8) 1200 bps (12). This LED is lit when the modem is connected at 1200 bps. 9) Off Hook (OH). This LED is lit when the phone line is "off hook". This occurs when the modem is dialing, on-line, or answering a call. This LED also flashes when the modem is pulse dialing in Command mode. 10) Terminal Ready (TR). When the TR LED is lit, the modem is permitted to answer an incoming call. When it goes off, a connected modem will disconnect. The state of the TR LED matches that of the DTR circuit on Pin 20 of the RS232C/V.24 interface. 11) Error Correction (EC). This LED is lit when the modem is set for V.42 error correction, and it will flash on and off when data compression is activated. 12) FAX (FX). This LED is lit when in connected in FAX mode. 1.10 Controls on PC Board The MT1432BA is designed on a single printed circuit (PC) board. This board contains one 16-position DIP-Switch (numbered 1-16), a 2-position "Flip"-Switch and several berg jumpers. The Switches are accessible through a cut-out on the side of the modem and the berg jumpers are accessible when the PC board is removed from its chassis. There is also a knob which is used to adjust the speaker volume. This knob is accessible through the modem's rear panel. The sixteen DIP-Switches, "Flip"-Switch and berg jumpers control various modem options or set default values for Command Mode operation. There is a difference in how several of the switches operate depending on whether you are in synchronous or asynchronous mode. Refer to the switch label on the bottom of the MT1432BA for an exact list of the switch functions in asynchronous and synchronous operation. Chapter 8 of this manual provides detailed instructions on configuring all of the MT1432BA's PC board options. 2.1 Introduction The installation of the MT1432BA consists of making the physical connections necessary to render the modem functional with your computer. This includes making the proper serial, phone line, and power connections. It is important to remember throughout this manual that all commands must be issued in terminal mode. This is the natural state of a computer/terminal; however, if you connect the MT1432BA to a PC, you must run a compatible datacomm program to enter terminal mode. (Refer to the proper corresponding datacomm software manual for this procedure.) This chapter covers MT1432BA installation and connection. The installation process involves: 1. Verify remote modem's current configuration settings with your MT1432BA in terms of data compression, error correction, transmission rate, etc. (per Chapter 4, Section 4.4.12/ATL5 and ATL7 Commands). 2. Attach MT1432BA to dial-up phone lines (Section 2.3.1) and/or leased lines (2.3.2) and verify DIP-Switch #10 and #5 settings. Refer to Figure 2-1. 3. Make sure modem and computer/terminal serial port baud rates are adjusted (Section 2.3.2). 4. Set both local and remote modems to either Normal (&E0&W0) mode or to Reliable (&E2&W0) mode (Section 2.3.3). 5. Verify leased line transmit level (DIP-Switch #3) setting (Section 2.3.3). 6. Attach your MT1432BA to your PC or terminal with an RS232 (or V.24) cable (Section 2.4). 7. Connect telephone set to phone jack (if desired) (Section 2.5). 8. Attach your MT1432BA to the AC Power transformer and plug the AC connector into a live AC outlet (Section 2.6). 9. Verify self-test results (Section 2.6). 10. Proceed to Chapter 3 of this manual. 2.2 DIP-Switch Settings Most communications software packages have installation procedures of their own, which call for certain modem DIP-Switch settings. If you are using a package other than MultiExpress, follow the software's instructions. The vast majority of installations are similar, with the MT1432BA being used to dial up a remote installation where the call is automatically answered. The factory default DIP-Switch settings are based on this assumption. Refer to Chapter 8 if the DIP-Switch settings must be changed. 2.3 Phone Line Connection 2.3.1 Dial-Up Lines The MT1432BA is designed for communications over Public Switched- Network Telephone lines. (It can also be connected to 2-wire leased lines.) Connection to the phone system is made via RJ11 type jacks such as an RJ11C or RJ11W. It can also be connected to an RJ41 or an RJ45S jack, but would not use these jack's dB-level programming features. The MT1432BA is designed to transmit at a permissive level of - 10dB. The MT1432BA uses two RJ11 jacks to connect the modem to the telephone lines, and if desired, a standard telephone set. One of the jacks is labeled Line Jack and the other is labled Phone Jack. To connect the modem to the phone lines, plug one end of the RJ11 cable that is provided with the modem into the Line Jack connector and the other into the phone- company-provided RJ11C or RJ11W modular phone jack. Make sure that DIP-Switch #10 is in the UP position (default) when in dial-up mode. DIP-Switch #10 must be DOWN when in leased line mode. 2.3.2 Leased Lines Although the majority of installations involves dial-up lines, the MT1432BA can also connect to two-wire leased lines (sometimes referred to as dedicated, private, or 3002 lines). No special line conditioning is needed, and operation is full-duplex over two wires. To connect the modem to leased lines, first determine the type of line termination provided by the phone company. Most phone companies provide a terminal block with a pair of screws. Some provide a conventional RJ11 type of connector. If the RJ11 connector is used, you can use the same cable that is used for dial-up connection. If the screw terminal type connector is used, you may need to order the #CA167 cable from Multi-Tech Systems. (Refer to Appendix H). Next, you need to make two DIP-Switch setting changes on the modem's PC board. The first involves DIP- Switch #10. This is used to change the modem from dial-up to leasedline operation. Place this switch in the DOWN position to accomplish this. The second DIP-Switch change is to set one of the two modems on the leased line circuit as the "originate" modem, and set the other as the "answer" modem. Although there is no dialing in leased line operation, the two modems still need to have their frequencies reversed so that they can talk to each other. This is what we mean by the terms "originate" and "answer". To do this you must change the setting of DIP-Switch #5. When you changed the DIP-Switch #10 setting, you also changed the function of DIP-Switch #5. Now the UP position selects answer mode frequencies while the DOWN position selects originate mode frequencies. On one of the two modems, place DIP-Switch #5 in the UP position, and on the other modem, place Switch #5 in the DOWN position. It doesn't matter which is which, just so you have one of each. When switching from dial-up to leased line mode, make certain that modem baud rate and serial port baud rate are adjusted correctly to your computer. Many computer's maximum serial port speed is 19.2K bps, and in switching from dial-up to leased line mode, the MT1432BA defaults to 57.6K bps (see $SB--Serial Port Adjust Command in section 4.4.11.). Once you have installed your modem on leased lines, operation is simpler than it was with dial-up lines. With leased lines, there is no more dialing. You're always on-line with the other modem as long as there is power connected to both modems. When the modems are operating asynchronously, both local and remote modems should be set identically in either &E2 Reliable or &E0 Normal mode. Some leased lines may require alternate transmit levels. The MT1432BA provides a choice of either 0 or - 10 dB. To increase the transmit level to 0 dB, place DIP-Switch #3 in the DOWN position (default). This should be done only for leased lines and should not be done for dial-up lines. Modems that are set for 0dB transmit level may not work "back-to -back" (with no phone line). Call Tech Support for further instructions. 2.4 Computer or Terminal Connections Your computer or terminal is connected to the MT1432BA via the modem's RS232C interface connector (or V.24 equivalent). This connector is a standard interface, with a 25-socket female connection. Therefore, your computer or terminal requires a standard RS232C cable with a male connector on the modem end, and a male or female connector at the computer or terminal end, depending upon the computer or terminal connector. Plug the RS232C cable into the RS232C connector on the modem, and secure it with screws which are included in most cable hood assemblies. Pin multi-tech eia CCITT signal circuit assignment designation circuit circuit source function 1 pg -- 101 -- Protective Ground 2 SD BA 103 DTE Transmitted Data 3 RD BB 104 DCE Received Data 4 RTS CA 105 DTE Request to Send 5 CTS CB 106 DCE Clear to Send 6 DSR CC 107 DCE Data Set Ready 7 SG AB 102 -- Signal Ground 8 CD CF 109 DCE Carrier Detect 9** +v +v -- DCE Test Voltage 12 HS -- -- DCE High Speed 15*** TC DB 114 DCE Transmit Clock 17*** RC DD 115 DCE Receive Clock 20 TR**** CD 108/2 DTE Terminal Ready 22 RI CE 125 DCE Ring Indicator 24 XTC DA 113 DTE External Transmit Clock 25 OOS CN 142 DTE Terminal Busy **Pin 9 need not be present in your RS232C cable ***Pins 15 and 17 are necessary only for synchronous operation ****Also known as DTR (Data Terminal Ready) Although the RS232C/V.24 interface connector is designed for 25 signal paths, only 14 or 15 of these signals are used by the MT1432BA. If your computer or terminal did not come with an RS232C/V.24 cable, you can get one from any supplier of computer equipment. A standard "straight-through" RS232C/V.24 cable will usually work. Note: any cables connected to the computer should be shielded to reduce interference. 2.5 Connecting a Telephone Set If you wish to have a telephone set connected to the same telephone line for voice communications, you may plug the telephone set into the modem's connector labeled PHONE Jack. This connector is provided as a convenience. It is possible to originate a data call with the MT1432BA using a telephone set and the Voice/Data switch. It is much easier to originate data calls using the Command Mode dialing features, and that method is recommended in nearly all applications. 2.6 Powering Up Power is supplied to the MT1432BA through the AC power transformer included with the modem. This transformer has a 2-prong AC connector, and an attached cord with a 2-pin connector at the end. The transformer bears the Multi-Tech logo. Connect the modem's AC power transformer to a live AC outlet, and connect the end of the power cord to the POWER connector on the back of the modem. As soon as you connect power to the modem, it performs a diagnostic self-test, indicated by the five speed indicators flashing in sequence for approximately four seconds, then the 14.4 indicator should light. If this does not happen, check that the transformer is solidly connected and that the AC outlet is live. Refer to Chapter 7 for more information on modem testing. The TR indicator should also light at the same time for most installations. The SD, RD, CD and OH indicators should also remain off at this time. 3.1 Introduction We'll assume that yours is the very common application, where you are using a MT1432BA to dial up a remote computer. The MT1432BA modem has been factory preset for originating a call to another compatible 14,400 bps modem (also set up for V.42 error correction, V.42bis data compression and CTS/RTS operation). If the answering modem is not set up similarly, the MT1432BA automatically adjusts to the appropriate protocol (Bell/CCITT Standards--not proprietary). 3.2 Dialing/On-Line/Answering There are several basic steps for "originating" and "answering" in data communication mode: 1. Load communication software 2. Dial 3. Establish On-Line connection 4. Terminate Call A simple way to dial is from the keyboard of your computer or terminal. You enter a command on the keyboard to tell the MT1432BA to dial. If you use one of the more sophisticated communications software packages, the software tells you to enter phone numbers and other information. If this is the case, the software, and not you, gives the dialing commands to the modem. All of the commands, option registers and intelligent features of the MT1432BA will be taken care of by the software. If you are giving commands directly to your modem (and not through your software), each command must begin with AT (ATtention Characters). AT characters may be entered in upper or lower case. Entering AT automatically sets the modem's speed to match the speed of the computer or terminal, and also sets the modem's parity. The AT characters alert the modem that a command follows. The AT Command can also be used to clear the command buffer, by simply typing AT and hitting RETURN. The letter D in a command causes the modem to dial the numbers immediately following it (e.g., ATD6127853500). You have a choice of either pulse (ATDP) or tone (ATDT) dialing methods. The MT1432BA responds with "CONNECT" on your video display after the number is dialed and a connection signal is detected (since the MT1432BA defaults to V.32bis/V.42/V.42bis, the actual response is "CONNECT14400 LAPM COMPRESSED"), if the MT1432BA "connects" with a similar modem (see section 4.3 Result Code Summary). The modem is now in "On-Line" mode, and is ready to communicate with a host site. If no connection signal is detected within 45 seconds (this time period can be adjusted by S-Register S7), the MT1432BA goes On Hook/hangs up and returns to Command mode. At this point, your video displays "NO CARRIER". Enter ATH to Hang Up On-Line (bring modem on-hook), and terminate the modem's On-Line mode. At this point, your video displays "OK". In addition to the call originating capabilities, the MT1432BA can also automatically answer incoming calls. You need not be present. You can, however, control the situation by configuring the modem to either answer or not to answer, or to answer after a specified number of rings. This is done by setting the value of S-Register S0 (modem defaults to automatically answer an incoming call after one ring). Refer to Chapter 5 for S-Register details. 3.3 Manual Call Origination You can use the MT1432BA to both originate and answer calls. To originate calls in the Asynchronous mode, you will most likely use the MT1432BA's Command mode, and give the modem automatic dialing commands. (We will delay our discussion of the Command Mode until Chapter 4.) When using your modem in the Synchronous mode, the Command mode is disabled, so you must automatically dial your calls with a telephone set. To use manual dialing, you must first connect an ordinary telephone set (either touch tone or rotary dial) to the modem's PHONE Jack connector. Next, you must set the speed selection, which is controlled by DIP-Switches #13 and #14, to the speed at which you wish to communicate. These DIP-Switches are located on the side of the modem (refer to Chapter 8 for DIP-Switch settings). Once your telephone set is connected, you can use it to dial the modem you wish to call. Simply dial the number, and then listen to the dialed modem's answer tone. When you hear it, press the Voice/Data switch on the front of the modem down (to the Originate position). You don't have to hold it down. Just press it once and let it go. Once you press the switch, the tone you hear should change to another pitch, or change into a rough-sounding scrambled noise. You then replace the telephone handset in its cradle, and your data communications can begin. Note that the MT1432BA may call manuallY via the keyboard command ATD, or by pressing the Voice/Data switch on the modem's front panel downward. To force the MT1432BA to automatically answer calls, either type ATA, or press the Voice/Data switch on the modem's front panel upward. 3.4 Automatic Answering The MT1432BA can be used as an automatic answering modem. No special modifications or settings are required other than making sure that the Auto-Answer select switch is set to auto-answer enabled (DIP-Switch #5 UP). The MT1432BA, when in its idle state, is set for originate mode frequencies. An incoming ring signal automatically switches the modem into answer mode. You can program the modem to answer a call after a certain number of rings using S-Register S0 (see Chapter 5). Refer to Section 3.6 for the handshaking procedures used by the MT1432BA when in automatic answer mode. In many originate only applications, you may wish to disable the automatic answer capability of the modem. If a telephone set is connected to the modem, you may wish to receive incoming calls in a voice mode for normal voice conversation. If auto-answer is not disabled, all incoming calls are answered by the modem, preventing voice communications. To disable automatic answer, place DIP-Switch #5 to the DOWN (Disable Auto Answer) position (refer to Chapter 8). Another way to disable automatic answer is to use S-Register S0 to configure the modem to answer on the nth ring, where n equals zero (0). Another alternative is to have the modem answer after five or six rings, which gives you time to answer it manually if you wish. (See Chapter 5 for S-Register information.) 3.5 Manual Answering We have shown that the MT1432BA can automatically answer incoming calls. The MT1432BA can also answer manually, under your control. The most typical application involves you and another person, who, after carrying on a voice conversation, want to convert to data communications between your modems without having to hang up and dial again. The problem here is that both modems are in originate mode. For two modems to communicate, one of them must be in originate mode and the other must be in answer mode. The solution here is to force either one of the two modems to answer mode, and the other to originate mode. The MT1432BA can be forced into either answer mode or originate mode, using the Voice/Data switch on the front of the modem. In our example, let's say that you and your friend Bill have just had a voice conversation. Both of you have your telephones connected to your MT1432BAs, and your modems are connected to computers or terminals. Set the speed switches to the proper speed on both modems. To switch to the data mode from the voice mode, you would switch the Voice/Data switch Down (to the Originate position), and Bill would switch his up to Answer. This switches your modem to the originate on-line mode, and Bill's to the answer on-line mode. You would both then hang up your telephone handsets, and continue the conversation via your keyboards. 3.6 Handshaking Details The following briefly explains what happens between two modems in a normal call. We are assuming that there are MT1432BAs at both the originating and at the answering end of the telephone line. (If other brands of modems are used with our modems, they will still communicate, but each manufacturer tends to use slightly different delay timings and sequences, and many of the brands vary in their LED designations.) When a call is dialed from the originating modem, the called modem responds to the ringing by switching into the answer mode and by turning on its RI (Ring Indicator, RS232C/V.24 Pin 22) signal as the rings are detected. Note that in order for the called modem to be able to answer the call, it must have a high DTR (Data Terminal Ready) signal. This signal comes from the computer or terminal to which it is attached, on RS232C Pin 20. (Note that the MT1432BA-MAC does not use DTR.) When the called modem answers the call, its OH (Off Hook) circuit comes on and the ringing stops. Two seconds after the call is answered, the called modem begins transmitting its answerback tone. The originating modem, which has been off hook and waiting for the answerback tone, turns on its transmitter when it hears the tone. Then after a one second delay, CD (Carrier Detect) will come on. The called modem then responds to the originating modem by turning on its CD (Carrier Detect) signal, and the handshaking is completed. Note: If you are using the Reliable or Auto-Reliable mode, some additional handshaking takes place. This is explained in Chapter 4, "Auto-Reliable Mode" ( section 4.4.8.). 3.7 Call Termination There are a number of methods by which you can terminate a call, or simply stated, hang up. They are: 1. Command Mode Control. To terminate a call by Command Mode, enter +++ATH then RETURN; or, send a BREAK signal followed by ATH and a RETURN. 2. DTR Control. If DTR (Data Terminal Ready) is turned off for 50 milliseconds or more, a disconnect occurs. This is probably the most common method used by computer systems at the automatic answer end of the line to cause the answering modem to disconnect after logging off procedures. 3. Loss of Carrier. After a data connection is established, the modem disconnects if a loss of carrier occurs for 700 milliseconds (0.7 seconds) or more. Note that one cause of carrier loss would be if one of the modems were to disconnect normally. 4. Abort Timer. Answer Mode: When OH (Off Hook) comes on, the called modem starts a forty-five-second timer and waits for a carrier signal from the originating modem. If carrier is not detected within this period, the modem disconnects (hang up) and is ready for another call. Originate Mode: The abort timer functions the same as in answer mode, except that the timer begins after the modem has completed dialing, instead of when it first goes off hook. It is possible to change this forty-five second wait period to any other value (from 0 seconds up to 255 seconds), or to disable the timer completely by reconfiguring S-Register S7 (see Chapter 5.) 5. Inactivity Timer. Causes the modem to disconnect if no data is being transmitted or received for a specified time. The timer is restored any time a character is passed through the serial port in either a send or receive state. This timer runs in both normal or reliable connections and is controlled by S-Register S30. The Inactivity Timer can be disabled by setting S30 to 0, which is the factory default setting. 4.1 Introduction AT commands are the means by which you, and your communications software, are able to communicate with and configure your modem. They enable you to establish, read, and modify parameters in addition to dialing. The following provides both a summary and a detailed explanation of the AT commands recognized by the MT1432BA. 4.1.1 AT Command Editing The BACKSPACE key on your keyboard can be used to edit characters in the AT command line. An AT command is not executed until the RETURN key is pressed. The BACKSPACE key erases the previous character for reentering. The BACKSPACE key does not erase the AT characters once they are entered. If your keyboard has no BACKSPACE key, CTRL-H does the same thing. The character recognized by the modem as BACKSPACE may be changed to any other ASCII character with S- Register S5. If you wish to cancel an entire command that has been entered but not yet executed, enter CTRL-X. This also clears the command buffer. The effect is the same as backspacing to cancel the entire command, only quicker. Characters entered in a command are stored in the modem's Command Buffer (memory) until executed by hitting RETURN. The Command Buffer's capacity is sixty characters. The Attention Characters AT do not count in the sixty allowed Command characters. Spaces, which may be used for increased display readability, may be used when entering a command, but are not stored in the Command Buffer and are not counted in the sixty allowed characters. Hyphens, parentheses, etc. are not allowed. If the sixty character limit is exceeded or if invalid characters are entered, the Command Buffer automatically erases, and an ERROR message appears. You would then re-enter your command within the sixty-character maximum, using only the allowed characters. 4.1.2 Functional Modes The MT1432BA can be in one of two functional states (see Figure 4-1). These are "Command mode" and "On-Line mode". (There is also an in-between state, "Wait-for-Carrier", where the modem is out of Command mode but not yet really On-Line. When the modem is initially powered up, it is in Command mode and is ready to accept commands from your keyboard or software. The MT1432BA enters On-line mode after dialing, making a connection with another modem, and then detecting a valid carrier signal. If no carrier is detected within a certain time frame, the modem abandons the call and re-enters Command mode. Once on line, the modem exits On-line mode if one of two conditions is met. If the carrier is lost or intentionally dropped, the modem hangs up and re-enters Command mode. Also, if the MT1432BA recognizes the Escape sequence for which it is configured (i.e., either the Escape characters in the serial data stream, the Remote Escape characters in the modulated data stream, or the Break signal), the MT1432BA will exit On-line mode, retain the datacomm link, and enter Command mode. You can force the MT1432BA into On-line mode without dialing by sending the ATD or ATA command to the modem. 4.2 Summary of AT Commands A wide variety of autodial operations and modem options can be controlled when the MT1432BA modem is in Command Mode. A brief summary of these commands follows below (remember, nearly all commands begin with AT.) These commands are organized into several functional groups. An alphabetical summary of commands is provided in Appendix C. HOW TO COMMANDS DIAL D Dial (Section 4.4.1) A: or : Continuous Redial $D DTR Dialing $VD Voice/Data Dialing $MI MI/MIC Dialing N Dial a Stored Number MODIFY DIALING P/T Pulse/Tone Dialing PROCEDURES &P Set Pulse Dial Ratios (Section 4.4.2) , Automatic Pauses in dialing Y Long Space Disconnect W Wait for New Dial Tone ; Return to Command Mode After Dial Command R Reverse Mode of Operation ! Flash On Hook $ "Call Card" Tones Detect @ Quiet Answer MEMORIZE PHONE NUMBERS D...N Store Phone Numbers (Section 4.4.3) NN Number Linking L List Numbers Stored in Memory STORE MODEM &F Load Factory Defaults CONFIGURATIONS &W Store Configuration & S-Register AND DEFAULTS Parameters (Section 4.4.4) Z Reset Modem V Result Code Terse/Verbose $SP UNIX/"Spoofing" &M Sync/Async Mode Select &X Synchronous Transmit Clock Select CONFIGURE Q Result Codes Enable/Disable Response COMMAND &Q Result Code Selection RESPONSES E Echo Command Characters (Section 4.4.5) V Result Code Terse/Verbose X Result Code...Basic/Extended/Call Progress CONDITION &G Guard Tones PHONE LINE M Monitor Phone Line (Section 4.4.6) &T Remote Digital Loop Signal #T Enable/Disable Trellis Coded Modulation B Bell/V.21 Tones #F Fallback When On-Line #A Auto-Speed Detect CONTROL RS232C &C Carrier Detect Control INTERFACE &D Data Terminal Ready Control (Section 4.4.7) &R Clear To Send Control &S Data Set Ready Control &RF CTS/RTS Control &SF DSR/CD Control CONFIGURE &E0 Normal Mode ERROR &E1 Auto-Reliable Mode CORRECTION &E2 Reliable Mode (Section 4.4.8) #L0 Negotiate V.42 Mode During Handshake #L1 MNP On/LAPM Off #L2 LAPM On/MNP Off #L3 Direct LAPM/Phase Out Handshake $A Auto-Reliable Buffering $F Enable/Disable Auto-Reliable Fallback Character $R Retransmit Count $E Error Correction at 300 bps CONFIGURE &E3 Flow Control Disabled FLOW CONTROL &E4 Hardware Flow Control (Section 4.4.9) &E5 Xon/Xoff Modem-Initiated &E6 Xon/Xoff Modem Responds/No Pass- Through &E7 Xon/Xoff Modem Responds/Pass- Through Allowed #X Send Single/Multiple Xoff Characters &E8 Enq/Ack Off &E9 Enq/Ack On &E10 Normal Mode Modem Flow Control Off &E11 Normal Mode Modem Flow Control On &E12 Computer-Initiated/Off &E13 Computer-Initiated/On FLOW CONTROL &BS Maximum Block Size CONFIGURE... $EB 10/11 bit Asynchronous Format (Section 4.4.9) #P Parity Selection CONFIGURE DATA &E14 Data Compression Disabled COMPRESSION &E15 Data Compression Enabled (Section 4.4.10) CONFIGURE SPEED $BA0 Speed Conversion On CONVERSION $BA1 Speed Conversion Off (Section 4.4.11) $MB Set modem speed (e.g.,$MB14400) $SB Set serial port speed (e.g.,$SB57600) EXECUTE $H Help IMMEDIATE I Product Code Inquiry ACTION L5 List Current Operating Parameters COMMANDS L6 List S-Register Values (Section 4.4.12) L7 List additional Configuration Parameters L8 List On-Line Diagnostics H Off Hook +++AT EscapeSequence:Entering Command Mode while On-Line %E EscapeSequence Options. . .Entering Command Mode while On-Line A Force Answer Mode O Exit Command Mode/Go Back On-Line READ AND Sr? Read Current S-Register Value ASSIGN Sr= Assign S-Register Value S-REGISTER VALUES (Section 5.1) REMOTE #CBN Passwords for Callback Phone Numbers CONFIGURATION #DB Callback Security Enable/Disable & CALLBACK #I Change LOGIN Password SECURITY #RCBNxx Erase Password (Section 6.1) Linked with Memory Location xx #S Change SETUP Password TEST MODEM U Self-Test Modem (Chapter 7) (Chapter 7) &T Enable/Disable Digital Loopback Signal 4.3 Result Codes The MT1432BA Command mode provides you with several responses, or "Result Codes", that can aid you in Command mode operation. These Result Codes are displayed on your video monitor. You can choose result codes that closely match those of the standard AT command set, or choose enhanced function result codes that have been used in Multi-Tech modems ("Multi-Tech" responses). The &Q command selects which result codes will be used. You can choose to have these Result Codes displayed in either "verbose" (full words) or "terse" (digits) format. This is controlled by the ATV0 (terse) or ATV1 (verbose) commands. The MT1432BA defaults to verbose format. AT&Q0 selects Multi-Tech responses with Reliable/Compression modifiers. The terse response code for CONNECT 2400 is 9. AT&Q1 selects Standard AT command set responses. The terse result code for CONNECT 2400 is 10. The following tables define the result codes generated by the &Q command (refer to Appendix F for Result Code Summary). &Q0 "Multi-Tech" Result Codes TERSE VERBOSE 0 OK 1 CONNECT 2 RING 3 NO CARRIER 4 ERROR 5 * CONNECT 1200 6 NO DIALTONE 7 BUSY 8 NO ANSWER 9 * CONNECT 2400 11 * CONNECT 4800 12 * CONNECT 9600 13 * CONNECT 14400 * When error correction is used, the word RELIABLE (verbose) or the letter R (terse) is added to these responses. When data compression is activated, the word COMPRESSED (verbose) or the letter C (terse) will be added to these responses. &Q1 "Standard AT" Result Codes TERSE VERBOSE 0 OK 1 CONNECT 2 RING 3 NO CARRIER 4 ERROR 5 CONNECT 1200 6 NO DIAL TONE 7 BUSY 8 NO ANSWER 10 CONNECT 2400 11 CONNECT 4800 12 CONNECT 9600 13 CONNECT 14400 Error Correction/Data Compression modifiers are not displayed with "Standard AT" Result Codes. 4.4 Dialing Commands 4.4.1 Dialing Action Commands Dial The letter D in a command causes the Command MT1432BA to dial the telephone number immediately following it. For example, if you D enter ATD5551212 and hit RETURN, the MT1432BA dials the number 555-1212. The D command is also used in conjunction with a telephone set for manual dialing. You dial the number on your telephone set, and after hearing the answer tone on your handset, you type ATD on your keyboard and hit RETURN. Then hang up the headset. Unless you have a specific need to dial in this manner, we recommend you use the first method, where the telephone number is entered on your keyboard. The MT1432BA gives you several choices of dialing methods. You can use tone or pulse dialing, by inserting a letter T or a P in the command string. (See Section 4.4.2 on Dial Modifiers). You can also configure the modem to either wait for and detect dial tones and busy signals (which we call "Wait-for-Dial-Tone" dialing or "Smart" dialing), or work with timed pauses without dial tone and busy signal detection (which we call "Blind" dialing; see Section 4.4.5, "X" Command.) Note: There is another method of dialing, called "DTR Dialing", where by manipulating the DTR signal on pin 20 of the RS232C/V.24 interface, a number stored in the modem's memory is automatically dialed. See Section on DTR Dialing ($D command) for details. Continuous Redial If you select the Wait-For-Dial-Tone method (not used in of dialing (see X3 or X4 command), you can MT1432BAI) command the MT1432BA to continuously redial (up to 10 redials for DOC units) a busy A: or : number until your call is answered. This is done with the A: command. This command would be used only if you had already reached a busy number after executing a normal dial command. You simply enter A: (you need not enter AT, nor do you need to hit RETURN), and the modem will redial the number for you. If you again reach a busy signal, it redials again and again until it no longer detects a busy signal. You can stop the MT1432BA from redialing by pressing any key. Another method used to cause the modem to redial a phone number continuously is to enter a colon : at the end of the phone number. The result is the same as if you had entered A: after personally observing that the number was busy on the first dialing attempt. Using the colon in the Dial command is a step saver. Dialing a Stored A telephone number that you have stored in the Number MT1432BA's number memory may be automatically dialed by entering ATNn where N n = 0, 1, 2, 3, 4, 5, 6, 7, 8 or 9. For example, a number stored at N3 would be dialed by entering ATN3 and RETURN. Do not include the letter D in this command, or the stored number will be erased (also see Section 4.4.3., on Phone Number Memory Commands). DTR An alternate method of causing the Dialing MT1432BA to automatically dial is DTR Dialing. Data Terminal Ready (DTR) is a signal that $D comes into the modem from the terminal or computer to which it is connected, on pin 20 of the RS232C interface. In DTR dialing, the modem automatically dials a stored number as soon as it receives a high DTR Signal. The DTR dialing method is popular in synchronous applications. To activate DTR Dialing, enter AT$D1 and hit RETURN. The modem dials the phone number stored in the N0 location of memory when it receives a high DTR signal. DTR must remain high for the duration of the call, until disconnect. To deactivate DTR dialing, enter AT$D0 and hit RETURN. Note when using DTR Dialing in a synchronous application, be sure DIP-Switch #8 is in the UP position to disable V.25bis Command mode. Voice/Data Another alternate method of causing the Dial MT1432BA to automatically dial is Voice/Data Dialing. With Voice/Data Dialing, the modem $VD automatically dials the phone number stored in the N1 position of memory whenever the Voice/Data switch is toggled. To enable Voice/Data Dialing, enter the command AT$VD1 and hit RETURN. To disable Voice/Data Dialing, enter the command AT$VD0 and hit RETURN. MI/MIC The MT1432BA is available with a modified Dialing dial-up phone line interface, called the " MI/MIC" option. This option is used in $MI applications where the modem's dialing capability is not used, and dialing is done by an external device (such as an 801 dialer, a computer, or a PBX/CBX systerm dialer). To activate MI/MIC option you must first move the MI/MIC jumper plugs as described in Chapter 8. The command $MI, then controls this function. AT$MI1 enables MI/MIC operation and AT$MI0 disables it. With the MI/MIC option enabled, the MT1432BA's A and A1 output leads of the telephone line interface are replaced with MI and MIC imput leads. (Tip and ring remain unaffected.) When MI and MIC are connected together, the modem goes off-hook in the originate mode, for a time period specified by the modem's Abort Timer (S-Register S7). The default setting for the Abort Timer is 30 seconds, but can be set to any value from 1 second up to 255 seconds. A 30 second Abort Timer means that if the modem does not detect a carrier tone within 30 seconds after it goes off-hook, it disconnects. 4.4.2 Dial Modifier Commands There are several command characters that can be included within a dialing command (following the letter D), called "Dial Modifiers". They have various functions, including the selection of Pulse or Tone Dialing, pauses in the dial sequence, automatic redials if a number is busy, and reverting to the Command mode or switching to the Answer Mode after dialing. Pulse or Tone Dial The MT1432BA dials numbers using either pulse or tone dialing, or a combination P of both methods. Pulse dialing is a method used by rotary-dial telephones, which T involves the timed opening and closing of line relay. Tone dialing is the method used by pushbutton (touch tone) telephones, and is sometimes referred to as DTMF, or Dual-Tone Multi-Frequency dialing. The method used is selected by including a P for Pulse or a T for Tone in the dialing command, right before the digits you wish to have dialed in that manner. For example, you would pulse-dial the number 555-1212 by entering ATDP5551212 and hitting RETURN. You could tone-dial the same number by entering ATDT5551212 and hitting RETURN. If neither Pulse nor Tone dialing is specified in the dial command, the MT1432BA uses whatever method used last. If the modem has been reset or just powered up, it uses Pulse dialing, even if the letter P is not included in your dial command. Nearly all telephone systems in the U.S. are now compatible with tone dialing. Since that is the faster method, you will probably choose the tone method for your dialing. An example of combining pulse and tone dialing could involve a PBX system where 9 had to be pulse-dialed first, then the rest of the number tone-dialed after pausing for a second dial tone. The number would be dialed by entering ATDP9, T5551212 and RETURN. (The comma causes a pause, which we'll explain soon.) Set Pulse This command sets the time ratios between Dial Ratios the open and closed portions of the dialing pulse frequencies. To set the dialing pulse &P ratio of 60 mSec to 40 mSec, enter AT&P0. To set a ratio of 67 mSec to 33 mSec, enter AT&P1. The factory default is &P0 (refer to Appendix B). Automatic You can cause the MT1432BA to pause during Pauses in the dialing sequence by entering a comma Dialing character where the pause is desired. , This pause will last two seconds. If a longer pause is desired, more than one comma may be entered consecutively, with each comma causing a two second pause. You also have the option of changing the length of the pause caused by the comma, from two seconds to any other value from 0 up to 255 seconds. This is done by setting S-Register S8 (refer to Chapter 5). Each comma in a dialing command counts as one of the sixty allowed characters. Long Space When two modems are connected in Normal Disconnect mode (i.e. without error correction) there is no "polite" means of requesting a disconnect. A link disconnect request packet is sent under Y reliable connections. As a result some "garbage" may be received when a hangup command is issued. The Y1 command enables the modem to use the break signal which accomplishes the hangup as an instruction to shut off its receiver and disconnect (both modems must have Y1 enabled for this feature to be effective). Y0 (factory default) disables this function. Wait for New A W inserted in the dialing command causes Dial-Tone the MT1432BA to wait for another dial tone, and not resume dialing until another dialtone is detected. W It is not necessary to enter a W at the beginning of the dialing command to wait for a modem dial tone, because the modem will do that first (pause automatically). In order for this command to work, you must select Wait-For-Dial Tone dialing with the X2 or X4 command, so that your modem will be able to detect the dial tone. Return to A semicolon (;), entered as the last character Command Mode of a dialing command causes the MT1432BA After Dial to return to the Command mode immediately Command after executing the command, instead of waiting Execution for a carrier signal and going on line. For example, entering ATDT5551212; would tone-dial the ; number, and do nothing afterwards except go back into Command mode. This can be useful in dialing applications where modem data transfer is not desired, such as voice communications, or in applications involving the use of touch tones as a data entry method, such as bank-by-phone. Reverse the In certain operations you may need to reverse Mode of the mode of operation for your modem from Operation originate to answer or answer to originate so that it would answer the phone and go into answer mode. R This command turns off the reversing function with the R0 command and turns it on with the R1 command with the modem in either command mode. If you want to reverse from the originate mode, use R (with no number) in the dialing string. Flash On Hook Some switchboard systems react to a momentary On Hook. An exclamation mark inserted ! in the command causes the modem to "flash" on hook for a half of a second, just as if you had held the switch hook button on a telephone set down for a half second. For example, to flash On Hook after dialing the number 555-1234 in order to transfer to Extension #5678, you might enter ATDT5551234,,!5678. The commas cause a 4 second pause (just to be safe). "Calling Card" The MT1432BA has the capability to detect Detect Tones AT&T "calling card" tones for the purpose of $ utilizing the user's calling card number to originate an on-line connection. An $ symbol placed in the dialing string causes the modem to pause and wait for an AT&T "calling card" or a 1600 Hz tone (prevalent in the United Kingdom). When the tone is detected, the rest of the dialing string is processed. If no tones are detected within the time period set by S-Register S7 (default 45 seconds), the modem will abort by indicating a NO CARRIER message. Hitting any key also aborts the $ command. An example of this command: Quiet Answer The @ command causes the MT1432BA to wait before processing the next symbol in the @ dialing string. The wait is for one or more ringbacks followed by 5 seconds of silence. If the time specified by S-Register S7 passes before the rings and silence, a NO ANSWER (R) result code is processed. The @ command is used for accessing a system that does not provide a dial tone. For example, ATDT5551212@6313550 causes the MT1432BA to dial the first number (555-1212) and wait for the time specified in S7 for at least one ringback and 5 seconds of silence. If a busy signal is detected, the MT1432BA hangs up and generates a BUSY result code. If it does not detect 5 seconds of silence, a NO ANSWER result code is generated after hanging up. If 5 seconds of silence is detected, the second number (631-3550) is then dialed. 4.4.3 Phone Number Memory Commands Storing Phone A telephone number and command line of up Numbers to sixty characters may be stored in the MT1432BA's number memory. As many as ten of these numbers D...N may be stored. Each number will be given a name, using the codes N0, N1, N2 up to N9. A phone number is stored by entering ATD, then the number as it would be dialed, along with any P, T, R, ; or comma characters, and then entering N followed by the number's "name," which would be any number from 0 through 9, and then hitting RETURN. For example, the tone-dialed number 1-612-631-3550 would be stored as number N3 by entering ATDT16126313550N3 and RETURN. The number is not dialed with this store command. When phone numbers are stored, the entire command line is also stored so that you can effectively create a macro for each number. For example, if you know a particular number needs to have extended result codes, detect busy or dial tone, error correction, Xon/Xoff flow control, pacing, and data compression enabled, the command line would be: ATX4&E1&E5&E13&E15DT16126313550N3. This would store the entire command at location N3. Number Linking You may command the MT1432BA to dial another number automatically if the first NN number dialed is busy. This would be useful in a situation where a computer can be accessed through more than one phone number. This is called "linking". To link the number in N1 to the number N2, simply enter ATN1N2 and hit RETURN. Several numbers can be linked in the same command. For example, you could link N1 to N2 to N3 to N4 by entering ATN1N2N3N4 and RETURN or you could link N1 to N2 and back to N1 and then back to N2 by entering ATN1N2N1N2 and RETURN. The only limit on the number of numbers that can be linked is the 60 characters allowed in a command line. Number linking can not be used with blind dialing, since busy signals would not be detected. You would have to select the Wait-for-Dial tone dialing method using the X Command in order to use the Number Linking feature. Listing Numbers Telephone numbers that you have stored in the Stored in MT1432BA's memory may be listed and Memory displayed with the L command. It will display all ten stored N numbers in a format like that L shown below. All digits and command letters will be shown. The number's "name" (0 thru 9) is shown first, followed by the complete dialing command and telephone number as originally entered. Simply enter ATL and hit RETURN to display these numbers on your video screen or printer. An example of an L Command listing is shown below : 0 T14082345678 1 T16125551212; 2 P9,T14089876543 3 T3738315,12101,16126313550 4 T6313551R 5 6 P9,4258513 7 8 X4&E1&E5&E13&E15DT16126313550 9 T12138880123 4.4.4 Configuration and Default Storage Commands Store Configuration The MT1432BA can store configuration & S-Register parameters and S-Register values Parameters in in its non-volatile read/write Random Access Non-Volatile Memory(RAM) memory. The &W command Memory does this, which prevents any reconfiguration &W from being lost on a power-down or Reset (ATZ) condition. &W0 (or AT&W) causes the MT1432BA to store your customized AT command settings and S-Register values in its nonvolatile RAM. &W0 also sets the modem so that it reads your customized settings stored in nonvolatile RAM when powered down or reset. (The &W0 command only changes the settings stored in nonvolatile RAM that you specifically intend to alter. All other default parameters are applicable.) W1 causes the MT1432BA not to store your customized settings to nonvolatile RAM so that,after powering down or resetting the modem, it reads the factory default settings stored in ROM. Loading Factory The &F command provides a choice between Defaults customized configuration settings in RAM &F and the factory default configuration settings in ROM. The &F8 and &F9 commands define the function of the &F command. The MT1432BA is shipped from the factory with a pre-configured set of command and S-Register default settings. This set of factory defaults can be recalled by issuing the &F command. In addition to being able to recall the factory-installed defaults, the &F command can also recall those defaults stored under &W0. This is done using the &F9 command. If you have stored parameters with the &W0 command and wish these settings to always be used as your defaults, you would enter &F9&W0.To return the &F command to read factory installed defaults, enter &F8&W0. &F8 is the factory default. Many datacomm programs, including MultiExpressTM and MultiExpress for WindowsTM, issue the &F command automatically- the &F9 command allows the user to select their own defaults.Note that the &F8/&F9 commands should be used with &W0. Modem Reset The Z command can be used to reset the entire Command Mode buffer and the result is Z the same as if you had disconnected, and then reconnected power to the modem. When an ATZ command is executed, the state of the &W command determines where the default values originate. &W0 defaults come from RAM and &W1 defaults come from ROM. Unix UUCP The MT1432BA can be configured in a Unix Spoofing environment that employs ACK flow control as a means of monitoring data integrity. The $SP MT1432BA can do "UUCP spoofing", where the modem is able to generate ACKs at the DTE interface. Data is transmitted more time efficiently because the delay of waiting for data to be received, then for an ACK to be returned at the remote end, is eliminated. The $SP1 command enables UUCP spoofing and the default command $SP0 disables UUCP spoofing. Async/Sync This command can be used to set the on-line Mode mode to either synchronous or asynchronous. Switching AT&M0 will set the MT1432BA to Asynchronous mode, and all communications will be &M Asynchronous, in both On-line and Command modes. AT&M1 causes the MT1432BA to communicate asynchronously when in Command mode and switch to synchronous mode while on-line. The modem defaults to &M0 (asynchronous communications) on reset or power-up. Synchronous The &X command selects the Synchronous Transmit Clock Transmit Clock Source in conjunction with Select DIP-Switch #11. DIP-Switch #11 in the UP position enables External clocking. DIP- &X Switch #11 in the DOWN position enables Internal clocking (default position). External clocking is when the DTE provides transmit clocking to the modem on pin 24 of the RS232C interface. &X0 is the default setting, which allows DIP-Switch #11 to control Internal/External Clocking (default Internal). Internal clocking is when the modem provides transmit clock to the DTE on pin 15 of the RS232C/V.24 interface. The &X1 command overrides DIP-Switch #11 and selects External clocking. If DIP-Switch #11 is UP (External clocking), you can not override Internal clocking. &X2 enables Slave Clocking. The &X2 Command causes the MT1432BA to generate the transmit clock timing (pin 15) from the receive clock (pin 17) from the DTE (therefore 15 and 17 are the same). In this mode (Slave Clocking), all timing is controlled by the receive clock. 4.4.5 Command Response (Result Code) Commands Echo Command If the MT1432BA is connected to a full-duplex Mode Characters computer, it may be necessary for the modem to be configured to echo back characters entered E while in the Command mode in order for them to be displayed. The E command is used to configure the Command Mode echo, with ATE0 disabling the echo and ATE1 enabling the echo (default). Result Codes The Q command enables or disables Result Enable/Disable Codes and the No Response Answer mode of operation and No Response Result Codes may be disabled altogether in Answer certain applications, such as computer-controlled auto dialing, using the Q command. ATQ1 disables Result Code transmissions. ATQ0 (or ATQ) enables Result Code transmission. Regarding No Response Answer, you may want the answer mode handled without responses and echo turned off, but want the originate mode still intelligent. This is called the No Response Answer mode. ATQ2 selects the No Response Answer mode. If you do not select any mode, the factory default setting (enable Result Codes) is automatically selected. Result Codes The MT1432BA gives you a choice between ("Multi-Tech" or the Multi-Tech Result Codes, and Result "Standard AT") Codes that more closely match the standard AT command set responses (see section 4.3). &Q AT&Q1 selects AT responses with no Reliable/Compression modifiers. With this command, the terse result code for CONNECT 2400 is 10. AT&Q0 selects Multi-Tech responses with Reliable/Compression modifiers. With this command, the terse result code for CONNECT 2400 is 9. Result Codes The V command controls whether the (Verbose/Terse) MT1432BA's result codes are displayed as word ("verbose") or single digit ("terse") messages. V For example, if after dialing, no carrier signal is detected, the resulting message can be displayed either as NO CARRIER, or as the digit 3. Entering ATV0 (or ATV) causes the MT1432BA to display the Result Codes as digits, while ATV1 displays them as words. If you do not select a method, the factory default setting causes the modem to display Result Codes as words. Result Codes (Basic The X Command is used to select and Extended) and one of two possible dialing methods Call Progress ("dumb" or "smart"), and to select various Selection response combinations related to these methods. You can choose to have certain X responses suppressed, or whether or not you want speed indications along with the CONNECT responses. You can also pick and choose certain responses in order to match up with "Standard AT" responses. (Refer to Appendix F for a summary of Result Codes.) The MT1432BA provides "Basic" and "Extended" Result Code sets. The difference between the two is the Basic set provides one response (CONNECT) to indicate a connection, while the Extended set provides several responses for different speeds (CONNECT, CONNECT 2400, CONNECT 4800, CONNECT 9600 and CONNECT14400). When the Extended set is chosen, you also have the option of matching them up with Standard AT 2400 response code sets, by including or not including the BUSY and/or NO DIAL TONE responses while excluding the DIAL TONE response. The X command is used to select which responses are provided. Regarding the MT1432BA's method of dialing, the MT1432BA can detect standard dial tones and busy signals. This capability ("smart dialing") allows the modem to wait for a dial tone, and when one is detected, to begin dialing immediately. The MT1432BA also can detect a distant busy signal, if after dialing, it reaches a busy number. This is useful because it allows the modem to immediately abandon a call, rather than wait 45 seconds for a carrier signal that will never come. S-Register S7 defines the wait for carrier time (refer to Chapter 5). The MT1432BA gives you a choice between the wait-for-dial- tone ("smart") method we just described, and blind ("dumb") dialing, where instead of detecting actual dial tones, the modem relies on timed pauses. When the wait-for-dial-tone method is chosen, the busy signal detection capability is also activated. The X command is also used to select which dialing method is used. Five different X commands are available (X0 through X4), with five different affects on the MT1432BA's Result Codes. X0 Provides the basic (short) result codes and provides "dumb" dial capabilities. X1 Provides the extended result codes and provides "dumb" dial capabilities. The remaining X commands affect Call Progress, and turn on Extended Result Codes. X2 Looks for dial tone only and will not provide a busy response. X3 Looks for busy only and not look for dial tone. X4 Looks for dial tone and for busy. The factory default setting is X0, which selects Basic Result Codes and the blind ("dumb") method of dialing. 4.4.6 Phone Line Conditioning Commands Guard Tones The &G command is used to control the presence or absence of guard tones from the transmitter when &G in Answer mode, at either 1200 or 2400 bps. Guard tones are used in Europe and other areas for the modem to function in the telephone systems. Guard tones are not used in the United States. &G0 (default), turns off CCITT guard tones. &G1 turns on 550 Hz guard tones. &G2 turns on 1800 Hz guard tones. Bell or V.21 Tone The B command selects the frequency that the modem uses for its answer tone. (The B answer tone is the tone transmitted by a modem receiving a call to the modem that called it, which initiates the handshaking between the two modems.) At higher speeds (2400 to 28.8 K bps) there is no conflict, because all use CCITT frequencies. At lower speeds (0-1200 bps), in the U.S., some modems use the Bell frequency of 2225 Hz. However, the CCITT specification for V.22 has an answer tone frequency of 2100 Hz. The ATB0 command enables CCITT frequencies including V.21 (300 bps) and V.23 (1200/75 bps). The ATB1 command enables Bell frequencies including Bell 103 (300 bps). The MT1432BA default is ATB0. Phone Line The MT1432BA has an internal on-board, Monitoring speaker which functions like the speaker in a Speaker telephone handset to enable you to monitor phone line activity. The M command can be used to determine when the speaker is operational. Entering ATMO disables M the speaker completely, while ATM1 causes the speaker to be on only until a carrier signal is detected. ATM2 causes the speaker to remain on at all times. ATM3 causes the speaker to be on during dialing and off during handshake. ATM1 is the default setting, and the one that should be used in most applications. Enable or Disable The MT1432BA has several self-test features Recognition (covered in Chapter 7). The tests are of Remote activated with different U commands, such as Digital Loop Signal ATU1, and so forth. The &T command is a phone line conditioning command that &T enables &T or disables the modem's ability to recognize the Remote Digital Loop (RDL) test signal. The AT&T4 command lets the MT1432BA respond to a RDL signal, and places itself in digital loop. The AT&T5 command causes the modem to ignore the RDL signal. The factory default is &T5. Enable/Disable This command enables or disables the Trellis Trellis Coded Coded Modulation of the MT1432BA. There is Modulation usually no need to disable (turn-off) Trellis codings except under an unusual line condition called impulse noise. AT#T0 turns Trellis coding off and AT#T1 turns Trelis coding on (factory default). Fallback Modes If line conditions deteriorate, the MT1432BA When On-Line automatically drops its transmission speed ("fallback"). The #F command controls the #F different ways the MT1432BA falls back. During operation, if the error rate becomes too great, the modem performs a retrain. If after the retrain, the error rate is still too high for 14400 bps operation, the modem initiates a retrain at 4800 bps. If after the first retrain the modem returns on line at 14400 bps, the modem then starts a counter and a timer. If three retrains occur within a two minute period, the modem falls back to 4800 bps. Entering AT#F0 (or AT#F) allows no fallback when on-line. AT#F1 allows the MT1432BA to fallback (based on the error rate or if three retrains have occurred within a two minute period) from 14.4K to 12K to 9.6K to 4.8K bps (factory default). The AT#F2 command enables incremental fallback from 14.4K to 4.8K but also enables fall forward (from 4.8K to 14.4K incrementally). AT#F2 is the factory default Auto Speed Detect The function of the #A command is to detect and select the operational data rates (the "starting" speeds) with which the MT1432BA uses for initial handshake and speed selection. #A Remember, this command does not control the originating data rate of the modem (that is done by the Modem Baud Rate command $MBn), but only the Answer mode "starting" speeds. Entering AT#A0 (or AT#A) causes the MT1432BA to operate starting at 14400 bps, with incremental fallback to 9600, 4800, 2400,1200 and to 300 bps. AT#A1 uses 14400 bps only. AT#A2 causes the modem to operate at starting speeds of 14400 bps, with incremental fallback to 9600 and 4800 bps. The AT#A3 command causes the modem to begin operation as a V.22bis modem at 2400 bps, with incremental fallback to 1200 and to 300 bps. AT#A0 is the factory default value. 4.4.7 RS232C Interface Control Commands Carrier Detect The &C command allows you to control the Control status of the Carrier Detect signal (CD-Pin 8) on the RS232C line. You have four choices. &C You can force the signal high, or allow it to act normally, or force the modem to reset when CD drops, or set it to stay high until the modem disconnects, go low momentarily, and then go high again. The last option is useful with some CBX phone systems and mainframe front ends, which require CD to act in this manner. To allow CD to act normally, enter the command AT&C1 (the factory default setting). To force CD on, enter AT&C0. To reset the modem to its current parameters when CD drops, enter AT&C4. o set up CD so that it drops for one second on disconnect and then comes up again, enter AT&C2. (If you want the drop time to be something other than one second, use S-Register S24 to change this value. Refer to the Chapter 5 instructions for S24. Data Terminal Data Terminal Ready (DTR) on pin 20 of the Ready Control RS232C interface is required in order for the MT1432BA to operate. A high DTR signal &D tells the modem that the device to which it is connected is active, or "ready" to communicate through the modem. If the signal is not being provided on the RS232C interface, you can force DTR high with DIP-Switch #1 (Chapter 8). DTR has some other MT1432BA functions. DTR can be used to trigger a dialing sequence, called DTR Dialing. The condition of DTR can also be used to cause the modem to reset to its default parameters, just as if you had given the modem an ATZ command. To do this, enter the command AT&D3 and hit RETURN. The modem will now reset itself whenever DTR is dropped from On to Off, and will also go on-hook (hang up) if it is on-line. Entering AT&D0 or AT&D causes the MT1432BA to ignore DTR. Entering AT&D1 causes the modem to go on-hook (hang up) with loss of DTR. The modem enters Command mode when DTR goes high again. Auto-answer is disabled while DTR is low. Entering AT&D2 causes the modem to go on hook with loss of DTR. The modem enters command mode when DTR goes high again. CTS Control The &R command allows you to control the Clear to Send signal (CTS-Pin 5) on the RS232C &R interface. You have three choices. You can force the CTS signal high, allow it to act normally, or set it to stay high hntil the modem disconnects, go low momentarily, and then go high again. The last option is useful with some CBX phone systems and mainframe front ends, which require CTS to act in this manner. To allow CTS to act normally, enter the command AT&R0. To force CTS on, enter the command AT&R1 (this is the factory default setting). When the modem goes on-line, CTS still provides flow control. To set up CTS so that it drops for one second on disconnect and then comes up again, enter the command AT&R2. (If you want the drop time to be something other than one second, use S-Register S24 to change this value. Refer to Chapter 5). Data Set Ready The &S command allows you to control the Control status of the Data Set Ready signal (DSR - pin 6) on the RS232C interface. You have &S three choices. You can force the signal high, allow it to act normally, or set it to stay high until the modem disconnects, go low momentarily, and then go high again. The last option is useful with some CBX phone systems and mainframe front ends, which require DSR to act in this manner. To allow DSR to act normally, enter the command AT&S1 (the default setting). To force DSR on, enter the command AT&S0. To set up DSR so that it drops for one second on disconnect and then comes up again, enter AT&S2. (If you want the drop time to be something other than one second, use S-Register S24 to change this value. Refer to Chapter 5.) CTS/RTS In typical operation, Clear to Send will follow Interaction Control Request to Send when the modem is on-line. In other words, if RTS goes off, CTS will go &RF off in response. The &RF0 command enables CTS to follow RTS. In some applications, however,it may be necessary for CTS to operate independent of RTS. &RF1 allows CTS to operate independently regardless of the state of RTS, and is the factory default. If this is the case, refer to the &R command for control of the Clear to Send signal. DSR/CD In typical applications, Data Set Ready (DSR) Interaction Control will follow Carrier Detect (CD). &SF0 enables DSR to follow CD, and is the factory default. &SF &SF1 enables DSR to operate independent of CD. If this is the case, refer to the &S command for control of the Data Set Ready signal. 4.4.8 Error Correction Commands You can use AT commands to place your MT1432BA one of three V.42 (error correction) modes of operation. These are the Normal, Auto-Reliable, and Reliable modes. Normal Mode In Normal mode of operation, the MT1432BA's V.42 error correction capabilities &E0 are disabled, and the modem functions as a non-error-correcting modem. Auto-Reliable Mode In Auto-Reliable mode during the handshaking procedures at the start of &E1 the on-line connection, the MT1432BA automatically determines whether or not the modem with which it is communicating is using V.42 error correction. If the MT1432BA determines that the other modem is using V.42, it switches itself into Reliable (V.42) mode and its error-correction capability is enabled. If it is determined that the other modem is not using V.42, the MT1432BA remains in Normal mode, without error correction. The default setting is Auto-Reliable mode (&E1). The method the MT1432BA uses to determine if the modem it calls is a V.42 modem involves the use of a "Link Request". When the MT1432BA is in Auto-Reliable mode and originates a call, it goes through normal handshaking procedures just like any dial-up modem. After establishing the on-line connection, the MT1432BA transmits a Link Request message to the answering modem. (The Link Request message is generally about 33 coded characters.) If the answering modem replies with an appropriate V.42 acknowledgment response, the MT1432BA switches into Reliable mode. Otherwise it stays in Normal mode. This V.42 Link Request handshaking procedure generally takes about five seconds. When operating in V.42 Reliable mode, the MT1432BA uses its memory, or buffer, to store data as it is received. During periods of error-caused retransmissions or compression slowdowns, this buffer may fill up. To prevent buffer overflow and subsequent loss of data, the modem uses "flow control" to signal the computer attached to its RS232C port that the modem buffer is close to being full. This causes the computer to pause in its data transmission until the modem is able to empty its buffer sufficiently to accept more data, at which time the modem signals the computer that it may resume transmission. (Flow Control is discussed in section 4.4.9). Reliable Mode In Reliable mode, the MT1432BA uses its V.42 error correction capabilities during all &E2 transmissions, and must be connected to another modem with a similar protocol activated (MNP or LAP-M). V.42 Mode Select The V.42 standard implements both MNP Class 3 & 4 and LAP-M error correction #L methods. The V.42 Mode Select command (#L) selects which type of error correction (MNP or LAP-M) your MT1432BA uses for transmissions. The various #L command options are as follows. #L0 Command The #L0 Command allows a pair of modems to negotiate which V.42 mode (MNP or LAP-M) will be used in their transmissions. Originate Mode a. If both modems have AP-M capability, the modems use LAP-M mode. b. If one or both modems do not have LAP-M capability and both have MNP, the modems use the MNP mode. Answer Mode a. The answering modem responds to either an MNP Link Request or LAP-M Originator Detection Pattern (ODP) signal depending on which the originating modem issues. #L1 Command The #L1 Command sets your modem to MNP error correction and disables LAP-M. This command is for Originate mode only. In Answer mode, the modem still accepts MNP or LAP-M. #L2 Command The #L2 Command sets your modem to LAP-M error correction, and disables MNP. This command is for Originate mode only. Answer mode still accepts MNP or LAP-M. #L3 Command In the prior commands, the modems use a two phase process to establish a V.42 connection (detection to establish whether the remote modem is also error correcting, and then protocol establishment to determine parameters and to establish the error correction connection). If you know that the other modem is a V.42 error correcting modem, and you wish to use LAP-M, the #L3 command disables the detection phase and goes directly to protocol establishment. Both modems must have #L3 in effect. Auto-Reliable In Auto-Reliable mode, the modem is given Buffering four seconds to establish a Reliable connection. After this four-second period, the $A modem drops to Normal mode. Any data which is received during this period is typically discarded. The $A command can be used to cause the modem to buffer (save) data that is received during this Auto-Reliable time-out period. This data will then be output by the modem after the CONNECT message. AT$A0 = Discard data received during auto-reliable time period. AT$A1 = Buffer data received during auto- reliable time period. The factory default is $A0. Enable/Disable In Auto-Reliable mode, the modem is given Auto-Reliable fourseconds to establish a Reliable connection. Fallback Character Ifa single CARRIAGE RETURN is received from the remote modem during this four $F second period, the Auto-Reliable modem assumes that the remote modem is not in Reliable mode and drops to Normal mode. The CARRIAGE RETURN is the only character which causes the modem to drop to Normal mode. Any other character will either be buffered or discarded. The $F command can be used to disable this fallback-to-Normal-due-to-CARRIAGE-RETURN feature. The Auto-Reliable fallback character ($F) and Auto Reliable buffering ($A) commands can be used together to cause the modem to buffer all data received up until the CARRIAGE RETURN, and then drop to Normal mode. All data received will then be output following the CONNECT message. AT$F0 = Do not fall back to Normal if CARRIAGE RETURN received. AT$F1 = Fall back to Normal mode if CARRIAGE RETURN received. The factory default is $F1. Retransmit Count If errors are received during a Reliable connection, the modem re-sends the block of $R data which contained an error. With the $R0 command, if another error occurs, the block will be re-sent again. The modem counts the number of times that a data block is re-sent. If the same block of data is resent 12 times and still has not been received properly, the modem assumes that the transmission line is unsuitable for transmission, and abort the connection. This retransmit counter is disabled by the $R1 command. When the retransmit counter is disabled, the modem keeps trying to send data and will not abort, no matter how many times the same block is resent. AT$R0 = Disconnect if retransmit count is exceeded. AT$R1 = Do not disconnect due to retransmits. The factory default setting is $R0. V.42 Error At 300 bps, error correction is not typically Correction/300bps used. $E1 lets the MT1432BA function at 300 bps in either Normal (&E0), Auto-Reliable (&E1) $E or Reliable (&E2) mode. $E0, which is the MT1432BA's default, disables 300 bps/V.42 error correction altogether. 4.4.9 Flow Control Commands Flow control refers to the techniques used by computer devices to stop and restart the flow of data to and from each other. Flow control is necessary so that a device does not receive more data than it can handle. In the case of the MT1432BA, there is a need for flow control in both directions. As illustrated on the next page, flow control for data passing from your computer to the modem is called Modem-Initiated Flow Control and flow control for data passing from the modem to your computer is called Computer/Terminal-Initiated Pacing. The MT1432BA supports both hardware and software Modem Initiated Flow Control. On the Computer/Terminal-Initiated Pacing side, it supports hardware and software flow control, and a special version used by Hewlett-Packard compatible systems called ENQ/ACK Pacing. The MT1432BA allows hardware and software pacing to be passed through the modem to the other end of the link so that your computer or terminal can control data start/stop activity through your modem. This is called Xon/Xoff Pass- Through. To state it simply, "Flow Control" is something the modem does to the computer, while "Pacing" is something the computer does to the modem. Hardware Flow With Hardware Flow Control, the modem uses its RS232C Control interface to control the flow of data from the computer or terminal to which it is attached. The CTS (Clear to &E4 Send) signal on Pin 5 of the RS232C interface is brought low to stop the flow of data, and is brought high to restart it. When you select Hardware Flow Control as your Modem Initiated Flow Control method, you will also be selecting it for Pacing. The difference between the two, however, is that Modem-Initiated Flow Control uses the Pin 5 CTS output signal, while Pacing uses the Pin 4 RTS input signal. Modem commands are used to select the method of flow control used by the MT1432BA when its error correction capabilities are used. These commands are covered in Section 4.4.9. If neither method is selected, the modem defaults to no flow control (&E3). Xon/Xoff Flow Xon/Xoff is the most commonly used method of flow Control control. Under this method, control characters known as "Xon" and "Xoff" are inserted by the modem into the &E% data to start and stop the flow of data from the computer or terminal to which the modem is attached. Xoff, which is a Control-S, stops the flow of data, and Xon, which is a Control-Q, restarts it. With regard to Binary Data, Xon/Xoff flow control is not recommended because an Xoff character may be part of the data and would trigger an Xoff of the modem or software package, which would halt data flow. Xon/Xoff So far, you have had three choices to make regarding Pass-Through pacing: &E7 1. You can set the modem to respond to Xon/Xoff pacing. 2. You can set the modem to respond to RTS pacing. 3. You can set the modem to ignore pacing completely. Well, we're not done with pacing yet. There's another choice you can make (which actually can apply to both pacing and modem-initiated flow control, although it applies mainly to pacing) and that is something called Xon/Xoff Pass-Through. This means that if your modem is set to respond to Xon/Xoff commands, you can have the modem do one of the following: 1. The modem responds to the Xon and Xoffpacing commands while at the same time allowing these commands to pass through the modem and on to the remote location. We call this "Respond, Pass-Through". 2. The modem responds to Xon/Xoff pacing, but does not allow the pacing signals to pass through the modem and on to the remote location. We call this "Respond, No Pass- Through". When Xon and Xoff commands are allowed to pass through the modem, the computer or terminal at the remote site will receive these commands, and depending on how it is configured, the computer or terminal may respond to them also. When two MT1432BAs are connected in Normal mode (not using error correction), Xon/Xoff can be used to control the flow of data between the modems. Flow Control can be turned on or off with the Normal Mode Modem Flow Control commands. When the modems are connected in Reliable mode, a different method of modem Flow Control is used, and the commands for Normal Mode Modem Flow Control are ignored. When you are using Speed Conversion in Normal Mode, you must activate the modem's Normal Mode Modem Flow Control. (Speed Conversion is explained in Section 4.4.11.) Send Xon/Xoff The #X phone interface command allows the MT1432BA Characters to send either a single or multiple Xoff characters at the modem's buffer full level. When the MT1432BA's buffer #X reaches it's "buffer full" level, the next character received causes another Xoff to be sent for for every character subsequently received by the MT1432BA. The AT#X0 command ( factory default setting) causes one Xoff to be sent until the buffer reaches the Xon level. The AT#X1 command causes an Xoff to be sent for every character received after the modem reaches its buffer full level. Hewlett-Packard If the MT1432BA is being used with Hewlett Packard ENQ/ACK Pacing (or similar) equipment that employs ENQ/ACK pacing, the modem can be configured to respond to ENQ/ACK commands, &E9 making it compatible with HP systems. Doing so does not affect any other flow control or pacing already configured in the modem. When configured for ENQ/ACK, the ENQ (Control-E) and ACK (Control-F) signals from the HP equipment will be accepted and responded to according to Hewlett-Packard protocol. Normal Mode When two MT1432BA's are connected in Normal mode Modem Flow (not using error correction), Xon/Xoff can be used to Control On to control the flow of data between the modems. Flow Control can be turned on or off with the Normal Mode &E11 Modem Flow Control commands. When the modems are connected in Reliable mode, a different method of modem flow control is used, and the commands for Normal Mode Modem Flow Control are ignored. When you are using Speed Conversion in Normal Mode, you must activate the modem's Normal Mode Modem Flow Control. (Speed Conversion is explained in Section 4.4.11.) Terminal/Computer As mentioned earlier, the MT1432BA can iniate flow Initiated Pacing control by issuing Xon/Xoff commands or toggling the CTS signal on the RS232C interface. The modem can also be configured to react to similar commands and &E13 signals from the computer or terminal to which it is attached via the RS232C interface. We refer to the computer or terminal initiated flow control as Pacing. When the modem is set for Pacing On, the modem will respond to the terminal or computer pacing. When the modem is set for Pacing Off, it will ignore pacing. In order for the MT1432BA to be set for Pacing On, a modem-initiated method of flow control must be previously selected. Once this is done, the MT1432BA will respond to either Xon/Xoff commands, or to the toggling of the RTS (Request to Send) signal on Pin 4 of the RS232C interface, depending on what you selected earlier as your Modem-Initiated Flow Control method. Maximum The maximum size of Reliable mode data blocks can be Block Size controlled with the &BS command. MNP 3 sends blocks of 1 to 64 characters. MNP 4 and 5 typically send &BS blocks of 1 to 256 characters and LAP-M typically send 128 characters. For MNP Classes 4 and 5/LAP-M, reducing the block size to 64 characters may give a smoother flow of data, and better throughput on noisy phone lines. Using smaller block sizes over good phone lines may cause a slight loss in throughput (speed). AT&BS0 = Maximum transmit block size of 64 characters AT&BS1 = Maximum transmit block size of 128 characters (LAP-M) 256 characters (MNP) The factory default setting is &BS1. Asynchronous The MT1432BA has an 11-bit capacity when operating Word Length asynchronously. The $EB command selects between Selection 11-bit and 10-bit operation. AT$EB1 enables the modem to function in an 11-bit format (one start bit, eight $EB data bits, one parity bit and one stop bit). $EB0 is the modem's default setting and enables the MT1432BA to operate in 10-bit format (one start bit, seven data bits, one parity bit and one stop bit). $EB is functional in both command and on-line mode. $EB0 automatically detects parity when any AT command is issued. Parity Selection The #P command enables the setting of parity. AT#P0 selects no parity. AT#P1 selects odd parity. #P AT#P2 selects even parity and is the default value. 4.4.10 Compression, Error Correction, Flow Control, Pass-Through and Pacing Commands The MT1432BA has a variety of commands to control its error correction and data compression options. These additional commands are listed below. (Remember to precede each command with the AT characters.) Normal/Auto-Reliable/Reliable Mode Commands: &E0 = Normal Mode &E1 = Auto-Reliable Mode* &E2 = Reliable Mode Modem-Initiated Flow Control Commands: &E3 = Disables flow control (no flow control) &E4 = Hardware flow control (CTS on/off and RTS on/off)* &E5 = Xon/Xoff flow control Xon/Xoff Pass-Through Commands: &E6 = Modem responds to Xon/Xoff characters, but does not allow Xon/Xoff characters to pass through to remote site.* &E7 = Modem responds to Xon/Xoff characters, and allows them to pass through to remote site. #X0 = Selects single Xoff character until Xon level returns* #X1 = Selects multiple Xoff characters after buffer levels is full. Enq/Ack Pacing Commands: &E8 = Enq/Ack method of pacing off* &E9 = Enq/Ack method of pacing on Normal Mode Modem Flow Control Commands: &E10 = Normal Mode Modem Flow Control off* &E11 = Normal Mode Modem Flow Control (Xon/Xoff) on Computer-or Terminal-Initiated Flow Control (Pacing) Commands: &E12 = Pacing off* &E13 = Pacing on (either RTS on/off or Xon/Xoff depending on the setting of &E4 or &E5).* Data Compression Commands: &E14 = Data Compression disabled &E15 = Data Compression enabled* *Factory Default setting 4.4.11 Speed Conversion Commands Speed conversion is a necessary part of data compression since data must be presented to the modem faster than it can handle data, if data compression is to be effective. Speed conversion allows the MT1432BA to communicate at one speed over the phone line, and at another speed at the RS232C interface. The speed (also referred to as "data rate" or "baud rate") can be fixed at the RS232 interface independently of the baud rate of the on-line transmissions.In addition to data compression, another popular application for speed conversion involves an auto-answer MT1432BA connected to a computer that does not have autobaud capability. This means that the computer must be set at a fixed baud rate, regardless of whether the modem is communicating over the phone line at 300, 1200, 2400, 9600 or 14,400 bps. In this application, speed conversion allows the modem to match its speed to that of the calling modem, while at the same time communicating with the attached computer through its RS232C port at a fixed baud rate, which can be preselected at 300, 1200, 2400, 4800, 9600, 19,200, 38,400 or 57,600 bps. Speed Conversion When using speed conversion, you must set the modem so that it does not adjust its speed at the RS232C $BA serial port, even if the modem does adjust its data rate. To turn Speed Conversion ON, enter the command AT$BA0. To turn Speed Conversion OFF, enter AT$BA1 and hit RETURN. The modem will now match its RS232C speed to that of the computer, and will adjust its speed to any changes in the computer's speed in Originate mode, or to the speed of the originating modem in Answer mode. The speed at which the modem communicates over the phone line will always be the same as the speed at which it communicates via its RS232C serial port. Modem Baud Rate The $MB command presets the MT1432BA's transmission baud rate for originate operations, (i.e .,the speed of the modem's transmissions over the telephone $MB lines when originating a call). With speed conversion, this transmission speed can be a different baud rate than the serial port speed. When the MT1432BA receives (answers) a call from another modem, it automatically switches its phone line transmission speed to match the calling modem. However, if the MT1432BA originates a call to another modem that is unable to connect at the baud rate of the MT1432BA, it automatically drops to a lower baud rate in an attempt to match the speed of that modem. For example, if the MT1432BA is set for 14400 baud and calls another modem that has a top speed of 2400 baud, it drops to 2400 baud. The command to set the Modem Baud Rate is AT$MBn, where n can be 75 (in CCITT V.23 mode) 300,1200, 2400, 4800, 9600 or 14400 as listed below: AT$MB75 = CCITT V.23 AT$MB300 = 300 bps AT$MB1200 = 1200 bps AT$MB2400 = 2400 bps AT$MB4800 = 4800 bps AT$MB9600 = 9600 bps AT$MB14400 = 14400 bps The factory default is 14400 bps. Serial Port Baud The $SB command presets the speed of the MT1432BA's Rate serial (RS232C) port, in both Originate and Answer modes. Speed conversion allows you to set this serial $SB port baud rate at a fixed speed of up to 57,600 bps, regardless of the modem's transmission speed setting. In order for this command to be effective, the modem's Speed Conversion feature must first be turned off with the $BA command. When Baud Adjust is on, the MT1432BA automatically adjusts its serial port baud rate to match the speed of the computer or terminal it is connected to, as soon as it receives its first AT command. However, in many applications, such as automatic answer, the modem may not receive AT commands, in which case it is very useful to be able to preset the serial port baud rate with this $SB command. In addition to setting the MT1432BA's serial port speed, this command also sets the speed at which the modem issues Command mode responses. The MT1432BA will accept AT commands at any speed, regardless of the speed preset by the $SB command. If the modem receives such a command at a speed that is different than the preset speed, the modem switches its serial port baud rate to match the new AT command speed, although the baud rate value stored by the $SB command remains the same. This provides you with a convenient way to switch the serial port speed, and still make it easy to go back to the original speed automatically the next time the modem is powered up or reset with an ATZ command. The command to set the Serial Port Baud Rate is AT$SBn, where n can be 300, 1200, 2400, 4800, 9600, 19,200, 38,400 or 57,600 bps as listed below: AT$SB300 = 300 bps AT$SB1200 = 1200 bps AT$SB2400 = 2400 bps AT$SB4800 = 4800 bps AT$SB9600 = 9600 bps AT$SB19200 = 19,200 bps AT$SB38400 = 38,400 bps AT$SB57600 = 57,600 bps The factory default is 57,600 bps. *Some serial ports, particularly those in older PC-compatible computers, may limit the performance of ahigher speed modem like the MT1432BA. The limiting factor is a circuit called a Universal Asynchronous Receiver/Transmitter, or UART. All data from your modem flows through it. 8250, 16450, and 16550 are UARTs typically used in PC-compatible computers. The 8250 is unreliable above 9,600 bps and the 16450 is unreliable above 19,200 bps. The 16550 UART, however, is reliable to at least 115,200 bps. With V.42bis data compression enabled, the MT1432BA can achieve throughputs approaching 57.6K (depending on line quality and file content). If you presently do not have a 16550 UART in your PC, we recommend that it be replaced with one. An alternative too, is to consider replacing your slow serial card with a Multi-Tech high speed Intelligent Serial Interface (ISI) card. It comes in two-port and eight-port versions for DOS/Windows and UNIX systems, and includes a 32 K buffer that eliminates data loss even at high speeds. See your dealer for details. 4.4.12 Immediate Action Commands Help Screens The Help command is designed to give you short $H explanations on how to use each MT1432BA command. The Help command can be quite useful if your manual is not handy and you are in the middle of a communications session. Although the explanations are quite abbreviated compared to those in this manual, they should prove to be helpful reminders when needed. At the time of this writing, we have three screens of Help information (Screen #1, #2 and #3), and more screens may be added in the future. The Help commands are structured so that you can call up one of three Help screens, as follows: AT$H1 = Help Screen #1 AT$H2 = Help Screen #2 AT$H3 = Help Screen #3 Inquiry for Some systems or software packages automatically Product Code check the "identification" of the modem with which they are communicating, by using the I command. I This "read" command lets the software determine the type of modem with which it is communicating. When ATI or ATI0 is entered, the MT1432BA responds with 247. When ATI1 is entered, the modem responds with a three-digit code indicating the firmware version number. When ATI2 is entered, the modem responds with MT1432BA. Listing Current The L5 and L7 commands list the current operating Operating parameters of your modem. This information can be Parameters very useful when you are changing communications software or when you are changing modem default L5 settings. The command to list the MT1432BA's current operating parameters is ATL5 for the basic parameters. The L7 ATL7 command will list additional parameters on the MT1432BA. Listing S-Register The L6 command lists the current values stored in Values the modem's S-Register. This information can be very useful if you wish to change S-Register values. L6 (Refer to Chapter 5 for more information on S-Registers). Listing On-Line The L8 command displays the current Diagnostics on-line CONNECT status of the MT1432BA. L8 This display can be printed and used as a modem status report or as diagnostic information (such as when calling Tech Support).This report is given only when on-line. To activate this command first type +++AT(on-line escape command while maintaing command mode), then type ATL8. What then displays on your monitor is your modem's current on-line condition (e.g., Link Type, Line Speed, Serial Speed, Type of Error Correction/Data Compression, Number of past Retrains,etc.). An example of L8 listing is shown below: ATL8 ****** ONLINE DIAGNOSTICS ****** LINK TYPE V.32bis LINE SPEED 14400 SERIAL SPEED 57600 ERROR CNTRL/COMPRESS LAPM COMPRESSED FALL BACK/FORWARD LOCALLY ENABLED LINE TYPE DIAL UP DATA FORMAT ASYNCHRONOUS LINE QUALITY 001 0=EXCELLENT, 8=FAIR, 16=BAD RECV. SIGNAL LEVEL -016.5 dBM TRANS SIGNAL LEVEL -013 dBM NUMBER OF RETRAINS 000 ROUND TRIP DELAY 000 ms (MEANINGFUL IN V32 MODE ONLY) Off Hook You can make the MT1432BA hang up (go On Hook). ATH1 brings the line Off Hook, just as ] if you picked up the telephone set. You can H hang up by entering ATH0 or ATH (the default is 0 when no number is entered). Escape Sequences- It is possible to cause the MT1432BA to enter Entering Command Command Mode after the modem has gone on- Mode While Still line with a remote modem, without disconnecting On-Line the call. This is done by entering an Escape Code. The default Escape Code used by the MT1432BA is +++AT three plus signs (+++) followed by the letters A and T,up to sixty command characters (most typically "H", to hang up), and a RETURN. The number of command characters allowed after +++ AT , is defined by S-Register S34. S-Register S34 defaults to ten command characters. When this is done, the modem escapes to Command Mode, executes the command (if any), and then remain in Command mode. For example, to hang up the modem at the end of a call, enter +++ATH and hit RETURN. There is no need to incorporate pauses before and after the plus signs, as done in earlier modems. BREAK The MT1432BA provides an alternative Escape method, using a Break signal as the Escape Code. The Break signal AT allows the start-stop DTE (data terminal equipment) to signal the modem without loss of character transparency. With this method, a BREAK signal is used instead of the three plus signs. The BREAK is followed by the letters A and T, up to 60 command characters, and RETURN. When this is done, the modem executes that command, but remains in On-Line mode unless the command was to hang up and/or reset the modem (an H or Z), in which case the modem would be in the Command Mode after executing that command. Readers interested in further information on the use of BREAK signals as escape codes may wish to consult the CCITT X.28 Recommendation. In the "Provisional Recommendation X.28 (Geneva 1977)", information on the topic can be found in Section 4.9, entitled "Escape from the data transfer state". More recent editions have been published in 1980, 1984 and 1988. CCITT publications can be obtained from Omnicom, Inc., 112 Park Street SE, Vienna, VA 22180, Phone 703/281-1135, FAX 703/281-1505. Escape Sequence As mentioned, the default escape sequence Options - Entering setting is for the modem to respond to the Command Mode +++ escape method. Optional settings are for While On-Line the modem to respond to the Break method, for the modem to respond to either the +++ or the Break %E Methods, for the modem to ignore both methods and not escape, for the modem to respond with no "OK" to +++, and for the modem to respond with "OK" to +++. The %E command is used to select these options, as follows: %E0 = Modem Won't Escape %E1 = +++ AT Method (default) %E2 = Break Method %E3 = Either +++ or Break Methods * %E4 = No "OK" Response to +++ * %E5 = "OK" Response to +++ *The %E4 and %E5 commands enable or disable an "OK" response, which is required by some software packages during an escape sequence. Force Answer Mode You can force the MT1432BA into Answer mode with the modem's A command. Entering ATA when A in Command mode immediately brings your modem off -hook, out of Command mode and into On-Line Answer mode, and causes it to transmit its carrier signal over the phone line. If no responding carrier tone is received by your modem within forty-five seconds (or some other time as determined by S-Register S7), your modem stops transmitting its tone, hangs up, and goes back into Command mode. Exiting Command You can bring the MT1432BA out of Command Mode, Going mode and back into On-Line mode by entering Back On-Line ATO (where O is the letter O, not the number 0). In this case, the O command reverses what was done by O entering the Escape Code. The O command will bring the modem into the same On-Line mode (Originate or Answer) that it was in prior to going into Command mode.