This manual is provided to you in electronic format. It is supplied for the sole purpose of documenting and supporting Mult-Tech Systems' products. Any translation, modification, or unauthorized copying of this manual is strictly prohibited. The information contained herein is protected by U.S. copyright laws and international treaties. This text only manual is based on the MT2834MR owner’s manual, P/N 82035702, Rev. C. 1.1 Introduction Welcome to the world of data communications. You have acquired one of the finest rack-mount intelligent modems available, the MT2834MR, from Multi-Tech Systems. This owner's manual will help you install, configure, test, and use your modem. Your MT2834MR is designed to operate in two modes. First, it functions as a 28,800 bps leased line modem with dialback security. Communications over leased lines have been popular for many years primarily over 4-wire lines using V.29 modulation techniques. There have been dial back-up features in some leased line modems, but the dial back-up was at a slower speed. Your MT2834MR uses V.34 modulation that is designed for full 28,800 bps full duplex operation over 2-wires. That means when the MT2834MR uses its dial back-up capability, performance does not suffer. The second MT2834MR mode of operation is as a standard ITU-T V.34 2-wire dial-up modem. As such, it has incorporated all the advanced features of other Multi-Tech intelligent modems. This manual documents all of the MT2834MR's features and capabilities, such as autodial, auto-answer, auto-fallback, number linking, option switches, phone number memory, call progress detection, and more. The next section will show you how to use this manual. The contents of each chapter are listed, so you will know where to turn for specific information. 1.2 How To Use This Manual This manual is divided into eight chapters. There are also several appendices at the end of the manual, most of which repeat information contained in the chapters, but in a more condensed form. The information contained in each chapter and appendix is as follows: Chapter 1 - Introduction & Description This chapter begins with a short introduction, followed by a guide (which you are now reading) to the use of the manual. We then provide a more detailed description of the modem, as well as a chart containing the modem's technical specifications. This is then followed by sections covering power, LED indicators and a brief summary of modem switch options. (Chapter 7 covers switch settings more thoroughly.) Chapter 2 - Dialing and Answering This chapter covers Answer mode operation in detail, as well as the handshaking procedures between two modems and an auto-answer application. Various methods of call termination are also discussed. Chapter 3 - Command Mode Operation This may be the most important chapter of this manual. It begins with an introduction and discussion of the MT2834MR's Command mode fundamentals. A flow chart is provided to illustrate Command mode and On-Line mode operation and the methods used to enter each mode. Next, there is a summary of the modem's commands and responses. We then go into a detailed explanation of each command, providing examples where applicable. Chapter 4 - S-Registers This chapter covers the MT2834MR's S-Registers, which are used to store and/or configure various modem options. All of the S-Registers are defined and explained, followed by instructions on accessing the S- Registers and reading or changing their values. Chapter 5 - Error Correction, Data Compression and Speed Conversion This chapter provides information concerning some of the advanced features of the MT2834MR. Features such as V.42 Error Correction, MNP 5 Data Compression, Speed Conversion and others enable your MT2834MR to operate at a higher level of efficiency than possible with standard AT command set features. Chapter 6 - Testing Your Modem This manual does not cover testing. For test information, refer to your MultiModemManager Owner's Manual. Chapter 7 - DIP Switches and Jumpers The MT2834MR's printed circuit board options are covered in this chapter. The DIP switch settings and on-board jumper plugs are explained in detail, including all default settings. Appendix B - Dial Pulses and Tone Dial Frequencies Appendix C - DIP-Switch Summary Appendix D - Result Code Summary Appendix E - S-Register Summary Appendix F - AT Command Summary Appendix G - V.25bis Operation Appendix H - RS232C Interface Specifications Appendix J - Escape Sequences Used by Multi-Tech Systems Appendix K - Remote Configuration 1.3 Description Each MT2834MR card has three integrated 28,800 bps MultiModems. Each of the three modems on the MT2834MR card can be configured independently from each other via the MultiModemManager (Model #MR4800). The rack can support and control up to 16 MultiModem cards, to a total of 48 modems per rack. Up to 254 racks can be networked, for a total of 12,192 modems on the network under control of a single PC. Refer to your MultiModemManager Owner's Manual for more information on the rack and its components. Perhaps the most significant extras incorporated in the MT2834MR are its V.42 error correction and V.42bis data compression features. With error correction and data compression, transmission errors are eliminated while increasing the modem's throughput by a ratio of up to 4:1, for an effective overall transmission rate approaching 115,200 bps. The MT2834MR 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. The MT2834MR is FCC-Registered for direct connection to the public telephone networks. No Data Access Arrangements (DAA's) are required. The MT2834MR is fully compatible with the Standard AT command set, and is therefore compatible with all of the popular communications software packages. 1.4 FCC Regulations for Telephone Line Interconnection 1. 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. Contact Multi-Tech Systems, Inc. for details of how to have repairs made. 2. When trouble is experienced, you must disconnect your modem from the telephone company's jack to determine the cause of the trouble, and reconnect your modem only when the trouble is corrected. 3. The modem cannot be connected to pay telephones or party lines. 4. If requested by the telephone company, you must notify them of the following before the MT2834MR is installed: a. The particular phone line (phone number) to which the connection is to be made. b. The FCC Registration Number: AU7USA-20673-MM-E c. The Ringer Equivalence: 0.3B d. Modems can only be connected to the phone lines through standard modular jacks. The Uniform Service Order Code (U.S.O.C.) for the standard modular jack which connect the modem to the phone lines are: RJ11C or RJ11W (single line) e. The manufacturer's name and model number: Multi-Tech Systems - Model MT2834MR 5. If the telephone company notifies you that your device is causing harm, unplug it. The telephone company may disconnect your service if necessary and also may change its facilities, equipment, operations or procedures which may affect operation of your equipment. Where practical, the telephone company must promptly inform you in writing of the temporary disconnect or change in service, give you the opportunity to make changes allowing uninterrupted service, and inform you of your rights to bring a complaint to the FCC. 1.5 Canadian Limitations Notice NOTICE: The Canadian Department of Communications 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. 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. CAUTION: Users should not attempt to make such connections themselves, but should contact the appropriate electric inspection authority, or electrician, as appropriate." This digital apparatus does not exceed the Class A limits for radio noise for digital apparatus set out in Department of Communications. 1.6 Compliance with BABT Requirements (MT2834MRK only) European Low Voltage Directive When correctly installed and maintained, the modem will present no hazard to the user. When correctly installed the modem will be connected to the PSTN or a PW and to a Data Terminal Equipment (DTE), whose modem connections comply with ITU-T recommendation V28. The DTE connections are therefore taken to be safe voltages (less than +30 volts). Approved for connection to telecommunications system specified in the instructions for use subject to the conditions set out in them Approval no. NS/3422/23/N/603030 (Model #MT2834MRK). Compliance with BS6305 Clause 6.2 BS6320 Clause 7.2 and BABT/SITS/82/005S/D a. The modem is suitable for connection to the Public Switched Telephone Network (PSTN) provided by British Telecommunications pic or Kingston Communications (Hull) plc. Circuit supply by British Communications, Mercury Communication or Hull City Council. Only direct exchange lines may be used, not shared service. The modem may be connected to private speech band. b. The modem is suitable for household, office and similar general indoor use. It is not suitable for use as an extension to a payphone. c. BT lines supplied must support either loop disconnect or multifrequency tone signalling. d. REN (Ringer Equivalence Number). The REN value of a unit is calculated from 3/n where n is the total number of units which can be connected in parallel which will still cause the standard bell (as defined in BS6305 Appendix D) to ring. REN values of less than 0.3 cannot be assigned. For apparatus which is not capable of forming part of a multiple installation, a REN value of 3 is assigned. REN = 1 If a telephone or other device is connected in parallel with the modem, the combined REN must not exceed 4. A BT supplied telephone may be assumed to have REN of 1.0 unless otherwise noted. The approval of this modem for connection to the British Telecom public switched telephone network is INVALIDATED if the apparatus is subject to modification in any material way not authorized by BABT or if it is used with or connected to: i. internal software that has not been formally accepted BABT. ii. external control software or external control apparatus which cause the operation of the modem associated call set-up equipment to contravene the requirements of the standard set out in BABT/SITS/82/005S/D. All apparatus connected to this modem and thereby connected directly or indirectly to the British Telecom public switched telephone network must be approved apparatus as defined in Section 22 of the British Telecommunications Act 1984. Compliance with BS6789: Section 3.1 and Part 2 a. The modem is not capable of allowing Auto Call using '999' or other PABX emergency numbers. b. Modes, other than modes 1,2 or 3 should not be used on the BT PSTN. This modem is a mode 1 device. c. Users are advised to check the numbers entered during the AutoCall set up phase prior to dialing. d. The user should not issue any sequence of commands to the modem which would cause the modem to exceed the maximum allowable pause of 8 seconds from the time the modem goes off hook until dialing begins. Compliance with BS6328 Part 1 and BABT/SITS/82/01/C (Use on Private Circuits) a. The modem is not suitable for use on circuits with British Telecommunications signaling at a nominal frequency of 2280Hz. b. The modem does not require signaling or otherwise employ the frequency range dc to 200Hz. c. The modem may be connected directly to a point-to-point two- wire or four-wire Private Circuit. d. The modem does not require dc from the Private Circuit for correct operation. The modem may be damaged if connected, in private circuit mode, to a circuit supplying dc current (the maximum permissible direct current is zero amps). e. The approval of this modem for connection to British Telecom Private Speech band circuits is INVALIDATED if the apparatus is subject to any modification in any material way not authorized by BABT or if it is used with, or connected to: i) internal software that has not been formally accepted by BABT. ii) external control software or external control apparatus which cause the operation of the modem or associated call set-up equipment to contravene the requirements of the standard set out in BABT/SITS/82/01/C. All apparatus connected to this modem and thereby connected directly or indirectly to British Telecom Private Speechband circuits must be approved apparatus as defined in Section 16 of the British Telecommunications Act. 1981. Compliance with DTI 83/009 a. The apparatus is only approved for compatible PBXs. Consult the supplier for an up to date list of compatible PBXs. b. There is no guarantee of correct working in all circumstances. Any difficulties should be referred to Multi-Tech. c. If sockets are required for connection to the PBX, use the BT post card only if BT owns the wiring to the PBX. This apparatus has been approved for the use of the following facilities: *Auto-calling *Loop disconnect and MF dialing *Phone number storage and retrieval by a predetermined code *Operation in the absence of proceed indication *Detection of initial and secondary proceed indication *Automatic storage of last number dialed *Tone detection-busy *Auto clear from the originating end *DTR dialing *Modem *PBX timed break register recall Any other usage will invalidate the approval of the apparatus if as a result, it then ceases to comply with the standards against which approval was granted. 1.7 Technical Specifications Tradename MultiModemV34 Model Number MT2834MR, MT2834MRK, MT2834MRI Data Rates (bps) Three independent modems(Modem A, B, C) each operating at 28,800, 26,400, 24,000, 21,600, 19,200, 16,800, 14,400, 12,000, 9600, 4800, 2400, 1200, or 0-300 bps Data Format Serial, binary, asynchronous at 0-300, 1200, 2400,4800, 9600, 14,000, 16,800, 19,200, 21,600, 24,000, 26,400,or 28,800bps; synchronous at 1200, 2400, 4800, 9600, 14,400, 16,800,19,200, 21,600, 24,000, 26,400, or 28,800 bps. Configuration Each of the card's 3 modems are independently configurable Compatibility ITU-T V.42, V.42bis, V.34, AT&T V.32terbo, ITU-T V.32, V.32bis, V.25bis, V.21, V.22bis, V.22, V.23, V.17, Bell212A* and 103/113* Error Correction MNP Classes 2, 3, 4, and LAPM Data Compression MNP 5, and V.42bis Speed Conversion Serial port data rates adjustable to 300, 1200, 2400, 4800,9600, 19,200, 38,400, 57,600, 115,200 bps Flow Control Xon/Xoff, Hardware CTS/RTS, ENQ/ACK Mode of Operation Full over both dial-up lines and 2-wire or 4- wire leased lines; automatic Dialback-up on separate lines in leased line operation, in dial-up mode; automatic or manual dialing, automatic or manual answer. Intelligent Features "Standard AT" command compatible, 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, Caller ID (optional feature), and on-screen displays for modem option parameters and up to ten telephone numbers/command lines of up to 60 digits each, help menus, remote configuration, and V.25bis dialing. Commands 100% compatible with "Standard AT" Compatibility Command Set Command Buffer 60 characters Automatic Dialing Choice of "Standard AT" command asynchronous dialing, "AT" command-controlled asynch-to-synch DTR dialing, or ITU-T V.25bis Synchronous or Asynchronous dialing. Automatic Leased When in dial back-up mode, modem will Line Restoral attempt leased line restoral periodically according to software configuration. Modulation Trellis Coded Modulation (TCM) at 28,800, 26,400, 24,000, 21,600, 19,200, 16,800, 14,400, 12,000, and 9600 bps; QAM at 9600 (non-trellis), 4800 and 2400 bps, PSK at 1200 bps, FSK at 300bps Carrier Frequencies Transmit Originate: 1200 Hz 2400 & 1200 bps Transmit Answer: 2400 Hz (V.22 or Bell 212A Receive Originate: 2400 Hz 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 Carrier Frequencies 1800 Hz (V.32) V.32 and V.32bis 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.21 CH2 (Half Duplex) Frequencies 1650 Hz Mark. 1850Hz Space for Transmit Originate 1650 Hz Mark, 1850Hz Space for Transmit Answer V.27ter 1800 Hz Originate/Answer V.29 QAM 1700 Hz Originate/Answer V.17TCM 1800 Hz Originate/Answer Transmit Level -10 dBm (dial-up) 0 dBm (leased line, MT2834MR) - 13 dBm (private wire MT2834MRK) -11dBm (MT2834MRI) Note: The Transmit Values apply to the domestic, U.K., and the standard International defaults only, country-specific modems may vary. Frequency Stability +0.01% Receiver Sensitivity -43 dBm under worst case conditions AGC Dynamic 43 dB Range Interface EIA RS232C Diagnostics On-line Diagnostics ITU-T V.54 Remote Loop, V.54 Digital Loop (with or without Pattern Generator) Offline Diagnostics ITU-T V.54 Analog Loop, Self-Tests Automatic Diagnostics Dial-up Tests Firmware Upgrades via Flash PROM technology on Multi-Tech's BBS Indicators LEDs for Transmit Data, Receive Data, Carrier Detect, 28,800 bps, 24,000 bps, 19,200 bps, 14,400 bps, 9600 bps, 2400 bps, Off Hook, Data Terminal Ready, Test and Out-Of-Service, Fax and Error Correction. Controls Toggle switches for Busy; DIP-Switches for various modem options. Operating 0 deg. to 50 deg. (32 deg. to 120 deg. F) Temperature Power 5 Volts DC at 0.95 Amp Requirements +/-16 Volts DC at 0.1 Amp Power Consumption Approximately 6 watts Dimensions, .9"x11"x15" (2.2x28x37 cm) HxWxD card modem Weight 2.5 Lbs. (1.1Kg) Limited Warranty Two Years Fuses F1 (+5V), F2 (-16V), F3 (+16V) 1.8 Power DC voltages are supplied to all of the modems in the CC4800 rack through one or two PS4800 power supplies, designed for conventional 115 or 230 VAC connection. The power supply is a universal input switching power supply. 1.9 Modem LED Indicators The MT2834MR has fifteen LED indicators. They are: 1. Transmit Data (XMT). This LED blinks when data is being transmitted, on for a space, off for a mark. The state of this LED matches that of the XMT circuit on Pin 2 of the RS232C interface. 2. Receive Data (RCV). This LED blinks when data is received, on for a space, off for a mark. The state of this LED matches that of the RCV circuit on Pin 3 of the RS232C interface. 3. Carrier On (CD). This LED lights when a valid carrier tone has been detected. 4. 28,800 bps (28.8K). This LED lights when the modem is set for 28,800 bps operation. 5. 24,000 bps (24K). This LED lights when the modem is set for 24,000 bps operation. 6. 19,200 bps (19.2K). This LED lights when the modem is set for 19,200 bps operation. 7. 14,400 bps (14.4K). This LED lights when the modem is set for 14,400 bps operation. 8. 9600 bps (96). This LED lights when the modem is set for 9600 bps operation. 9. 2400 bps (2400). This LED lights when the modem is set for 2400 bps operation. If the 2400 or 9600 indicators are not on, this indicates that the modem is set for 300 bps operation. 10. Off Hook (OH). This LED lights when the phone line is "off hook." This will occur when the modem is dialing, on line, or answering a call. The indicator will also flash when the modem is pulse dialing in Command mode. 11. Data Terminal Ready (DTR). When the DTR LED is lit, the modem is permitted to answer an incoming call. When it goes off, a connected modem will disconnect. The state of this LED matches that of the DTR circuit on Pin 20 of the RS232C interface. 12. Error Correction (V.42). This LED lights when the modem is in error correction mode, and flashes on and off when data compression is enabled. 13. Fax (Fax). This LED lights when the modem is in Fax mode. 14. Test Mode (Test). This LED lights during test mode operation. With the optional MultiModemManager Software installed, a full suite of modem tests can be controlled from a central PC. Refer to the MultiModemManager Owner's Manual for more test information. The Test LED lights during any of the software-control diagnostic tests. 15. Out-Of-Service (OOS). When the OOS LED is flashing, the leased line is down and the modem is in dialback mode or the self-test has failed. When OOS LED is continuously lit, the modem is in busy out/out of service (OOS) state. Note: The PS4800 modem rack power supply has one LED that indicates the presence of all supply voltages. 1.10 BUSY Switch The MT2834MR contains three two-position BUSY switches on the front panel. Each switch can be used to create a "busy out" (OOS) condition for one of the three on-board modems (i.e., Modem A, B, or C). To place a modem in the Busy condition, move the appropriate BUSY switch to the right. The selected modem goes off-hook, its OOS and OH LEDs light, and incoming calls to this modem get a busy signal. If you suspect a problem with a particular modem, you can use the BUSY switch to have an optional device (such as a "hunt group") that looks for a non-busy line to perform a "roll over" to the next available modem while you check the status of the Busy modem. NOTE: The MultiModemManager can perform the same function using software. 1.11 Controls on PC Board The MT2834MR modems contain three 16-position DIP-Switches and several jumper plugs. The DIP-Switches control various modem options or set default values for Command mode operation. There are also "jumper" option settings on the circuit board, which control V.54/Test (OOS) functions. The toggle switch positions on the MT2834MR are be labeled "Busy" for each of the three on-board modems (Modems A,B,C). Chapter 7 of this manual provides detailed instructions on configuring all of the MT2834MR's DIP-Switches and jumpers. 1.12 MT2834MRK Installation Notes The installation instructions include information about the use of blanking plates to cover empty slots in the card frame. Be sure to follow the instructions on installation that are provided in your MultiModemManager Owner's Manual. Warning: Interconnection directly, or by way of other apparatus, of ports marked 'SAFETY WARNING see instructions for use' with ports marked or not so marked may produce hazardous conditions on the network. Advice should be obtained from a competent engineer before such a connection is made. This product is intended to be hard wired to the network. The final connection to the network is the responsibility of the public telecommunications network operator or a person authorized by that operator. Any other apparatus, including cable and wiring, connected between the MT2834MRK modem and the point of connection to any speechband circuit shall comply with the following: (1) the overall characteristics of this apparatus shall be such as to introduce no material effect upon the electrical conditions presented to one another by the modem and the speechband circuit; (2) the apparatus shall comprise only; (a) apparatus approved (see note) for the purpose of connection between the modem and a speechband circuit; and (b) cable and wiring complying with a code of practice for the installation of equipment covered by this part of BS 6328 or such other requirements as may be applicable. Note: Such apparatus may have been approved subject to limitations in its use. 2.1 Introduction This chapter describes the dialing and answering capabilities of the MT2834MR. Since the modem can be either a leased line with dialback modem or a standard ITU-T V.34 full duplex dial-up modem, both modes are described (in terms of dialing features) in this chapter. 2.2 Automatic Leased Line Restoral Operation When the MT2834MR is in the dial back-up mode of operation, it will periodically check the leased line to see if it's operational and try to restore the leased line if possible. This is the automatic leased line restoral feature.* The frequency of the restoral feature attempts are determined by the contents of S-Register S18. The default for S18 is 30 minutes and can be set in one minute increments from 10 to 255 minutes. Setting the restoral frequency under 10 minutes causes excessive breaks in the dial-up operation. 2.3 Manual Dial Backup Call Termination If your MT2834MR is in the leased line mode (DIP Switch #10 in the Down ("Closed") position) and with a dial back-up operation in process, there are two ways to manually terminate (other than automatic leased line restoral) the dialback call. In each of these cases, you will be attempting to establish the leased line connection because it is back in operating condition. * Both local and remote modems should have S-Register S18 set identically. The methods of dial-back call termination are: 1. DTR Control. If DTR (Data Terminal Ready) is turned off for 50 milliseconds or more, a disconnect will occur. 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. 2. Command Mode Control. It is possible to enter Command Mode while remaining on-line by entering the Escape Sequence (+++AT in most cases). After you have entered Command mode, you may either return to the On-Line by typing ATO, or terminate the call with the H command. Typing ATH will hang up the line (bring it on-hook), bringing the modem out of the On-Line mode. So, the command to hang up a call is three plus signs, and then ATH. 3. Loss of Carrier. After a data connection has been established, the modem will disconnect if a loss of carrier occurs for 700 milliseconds (.7 seconds) or more. The 700 mSec time can be configured for any time from 0 to 25.5 seconds, in 100 mSec increments, with S- Register S10. Note that one cause of carrier loss would be if one of the modems were to disconnect normally. S10 works for speeds of 2400 bps or below, otherwise carrier loss will take about 20 seconds in a V.34 connection. 2.4 Dial Back-up Leased Line Restoral The dialing associated with the MT2834MR when it's operating in leased line with dialback mode, involves the placing of a call from the originating modem due to a leased line failure. The call can be placed automatically by the modem when the below described conditions are met. The dialback condition is indicated by the OOS LED blinking. After a preset period of time (determined by S-Register S18), the modem will try and restore the leased line automatically. The parameters used to determine whether a leased line is down (so that automatic dialback can occur), is based on the MT2834MR doing a retrain on the leased line due to an error condition in the transmission. An error condition is defined as a "hit" on the line (the Carrier gets interrupted). The retrain is a "handshake" procedure between the modems to establish the Carrier again. If the retrain fails, both modems (originate and answer modems) start their Dialback timers. The time is determined by the setting of S-Register S19. The default for the time is one minute. During that minute, the originate modem will try to establish the leased line link. If during that time, the leased line is established, the timer is cleared and everything is back to normal. If the timer expires the modems will go to dialback mode. The purpose of the timer for the Answer modem is to determine when it will accept a dial-up call. When both timers have expired and the leased line has not been established the dialback procedure will start. The number dialed is the one stored in location N9 of the originate modem's phone number memory. In preparation for proper dialback operation, you must enter the proper number in the N9 location using the commands detailed in Chapter 3. Keep in mind that the number also can be a V.25bis command for synchronous operation. 2.5 Dial-up Automatic Answering With your MT2834MR in the dial-up mode (12-Position DIP Switch #10 in the UP position), the MT2834MR can be used as an automatic answering modem. The MT2834MR, when in its idle state, will be set up with originate mode frequencies. An incoming ring signal will automatically switch the modem into answer mode. You can program the modem to answer a call after a certain number of rings by using the modem's S-Register S0. (See Chapter 4). Refer to Section 2.6 for the handshaking procedures used by the MT2834MR in an automatic answering application. 2.6 Dial-up Handshaking Details With your MT2834MR in the dial-up mode (12-Position DIP Switch #10 in the UP position), the following briefly explains what happens between two modems in a normal call. We are assuming that there are MT2834MR's 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.) Before V.34 negotiation takes place, remote and local modems transfer their functional capabilities using modulated calling and answering tones. First, the Calling Menu (CM), a data sequence using V.21 low- band modulation (a handshaking technique originally developed for 300 bps modems), is sent from the originating V.34 modem to the answering V.34 modem. This describes the range of functional capabilities the originating modem supports. The answering V.34 modem responds to the CM with a Joint Menu, or JM (using V.21 high- band modulation), indicating the common capabilities of the modem at each end. Once this is done, a probing signal is passed between the modems to identify impairments in the telephone channel. After receiving the results of the probing signal, the modem receivers and transmitters will start with the lowest speed and move up until reaching the highest speed at which they can exchange data. All this occurs in about five seconds. Note: 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, or it can be forced on by a switch in the modem. Note: If you are using the Reliable or Auto-Reliable mode, some additional handshaking takes place. This is explained in Chapter 5, in the "Auto-Reliable Mode" section. 2.7 Call Termination With your MT2834MR in the dial-up mode (12-Position DIP Switch #10 in the UP position), there are a number of methods by which you can terminate a call, or simply stated, hang up. They are: 1. Command Mode Control. It is possible to enter Command Mode while remaining on-line by entering the Escape Sequence (+++AT in most cases). After you have entered Command Mode, you may return to the On- Line state by typing ATO, or you may terminate the call with the H command. Typing ATH will hang up the line (bring it on-hook), bringing the modem out of the On-Line state. So the command to hang up a call is three plus signs and then ATH. 2. DTR Control. If DTR (Data Terminal Ready) is turned off for 50 milliseconds or more, a disconnect will occur. 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 log off procedures. 3. Loss of Carrier. After a data connection has been established, the modem will disconnect if a loss of carrier occurs for 700 milliseconds (.7 seconds) or more. The 700 mSec time can be configured for any time from 0 to 25.5 seconds, in 100 mSec increments, with S- Register S10. Note that one cause of carrier loss would be if one of the modems were to disconnect normally. S10 works for speeds of 2400 bps or below, otherwise carrier loss will take about 20 seconds in a V.32/V.32bis connection. S10 has no affect at V.32/V.32bis speeds. 4. Abort Timer. Answer Mode: When OH (Off Hook) comes on, the called modem will start a 45 second timer and wait for a carrier signal from the originating modem. If carrier is not detected within this period, the modem will disconnect (hang up) and be ready for another call. Originate Mode: The abort timer will function the same as in the answer mode, except that the timer will begin after the modem has completed dialing, instead of when it first goes off hook. It is possible to change this 45 second wait-period to any other value from 1 second up to 254 seconds by reconfiguring S-Register S7 (see Chapter 4). 5. Inactivity Timer. Causes the modem to disconnect if no data is being transmitted or received for a certain period of time. The timer is restored anytime a character is passed through the serial port in either a send or receive case. This function is controlled by S- Register S30. The inactivity timer can be disabled by setting S30 to 0, which is the normal factory default, or set to time out after the time selected by the state of S- Register S30. 3.1 Introduction The MT2834MR incorporates a microprocessor-based Command Mode, which allows you to use your computer keyboard or communications software to interact with your modem. When your modem is in Command mode, you have access to a complete communications system which allows you to use a number of features including the basic AT command set described in this chapter. The basic AT command set allows you to type phone numbers for automatic dialing without a telephone set, configure various modem options and monitor phone activity. Beyond the basic AT commands and capabilities, your modem can also perform advanced features such as error correction, data compression, speed conversion and more. Some of those features are covered in Chapter 5 of this manual. This chapter explains Command mode, and shows you how to use each of the basic AT commands. The MT2834MR AT commands and responses are compatible with all systems and software that have been programmed for automatic, software-controlled autodialing using the standard AT command set. The MT2834MR also provides V.42 error correction (using the MNP or LAP-M protocols), data compression (using the MNP) Class 5 and V.42bis protocol), speed conversion, and remote configuration. These advanced features are described in either Chapter 5 of this manual. 3.2 Typographic Conventions Used in This Manual It is important to point out the difference between the letter O and the number 0. Both of these characters will be used in the MT2834MR's commands. As you can see, the letter O is "fatter" than the number 0. We do not use the overstriken 0 to symbolize zero in this manual. The Carriage Return and Control keys are used in many of the MT2834MR commands. Some keyboards label the Carriage Return key as ENTER, others use the word ENTER, and still others use an arrow pointing down and then left. The symbol is also commonly used. In this manual, we symbolize Carriage Return with the word ENTER, and will usually use the phrase "hit ENTER" to instruct you to press the Carriage Return key. We symbolize the Control key with CTRL. For example, Control X, which is accomplished by pressing the X key while holding down the Control key, is written as CTRL-X. 3.3 Functional Modes The MT2834MR can be in one of two functional modes. These are "Command mode," and "On-Line mode." (There is also an in-between mode, "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, and respond to any Command Mode commands (described later). The MT2834MR enters On-Line mode after dialing and making a connection with another modem, and then detecting a valid carrier signal tone. If no carrier signal is detected within a certain time, the modem abandons the call and re-enters Command mode. Once On-Line, the modem exits On-Line mode if the carrier signal is lost or intentionally dropped. When this happens, the modem hangs up and re-enters Command mode. The MT2834MR can exit the On-Line mode without losing the carrier signal. This is accomplished by typing certain "escape" characters while on-line, which brings the modem back into Command mode without terminating the connection. The MT2834MR can also enter On-Line mode without going through the dialing process, by typing either the O command or the A command. This is explained later in this chapter, as are all of the MT2834MR's commands. 3.4 AT Commands A variety of autodial operations and modem options are controlled when the MT2834MR is in Command Mode. This chapter covers each command in detail. There are also several option configurations stored in "S-Registers", which can be accessed in Command Mode (refer to Chapter 6). Error Correction commands are covered in Chapter 5 of this manual. The MT2834MR commands are listed below in alphabetical order in a format that will help you remember the command. Modem Configuration - Command Letters AT ATtention code that precedes most commands A Answer mode A/ Repeat Last Command A: Continuous redial until call answered* &A Answerback (proprietary feature) $An Auto-Reliable Buffering #An Auto Speed Select $AS IBM AS/400 Support Bn Bell or ITU-T answer tone select &Bn Transmit Buffer size &BSn Maximum TX Block Size $BAn Baud Adjust &Cn Carrier Detect control *C Caller ID Detection (optional) Ds Dial DsDn Store Telephone Number &Dn DTR Control $Dn DTR Dialing En Echo Commands $En Enable/Disable Error Correction %En Escape Method $EBn Asynchronous Word Length &En Mode [normal, auto-reliable, or reliable] &En Flow control [None, CTS, or Xon/Xoff] &En Pass through XON/XOFF &En Enq/Ack pacing &En Normal mode flow control &En Pacing &En Data compression disable/enable $F Enable/Disable Auto-Reliable Fallback Character #F Fallback modes when on-line &F Fetch Factory default values $Fn Enable/Disable Fallback character #Gn Guard tones* H Hook on/off control, or Hang up $H Help screens I Identify modem model/revision #L V.42 mode select (LAP-M/MNP) L List stored telephone numbers L5 List current configuration parameters L6 List current S-Register Values L7 List additional configuration parameters L8 List On-Line Diagnostics &Ln Lease line commands $MI MI/MIC Control* Mn Sync/Async control $MBn Modem Baud Rate Nd Dial Stored Telephone Number NdNe Number Linking O On-line from Command Mode P Pulse Dial &Pn Set Pulse dial ratio* #Pn Parity Select Qn Result Codes &Qn Command set select Rn Reverse this mode &Rn CTS control &RFn CTS follow RTS control $Rn Retransmit count S= S-Register, set value S? S-Register, read value $SBn Serial port Baud rate &Sn DSR control &SFn DSR follow CD control $SP UNIX UUCP Spoofing T Tone dial #T Enable/Disable Trellis Coded Modulation &Tn Recognise RDL signal U U-loop test Vn Verbose or Terse result codes W Wait for new dial tone &Wn Store configuration in RAM X Extended or basic Result Codes and Call Progress &Xn Clock select Yn Long space disconnect Z Zap (reset modem) +++ Escape to Command Mode when on-line , Pause in dialing ; Revert to Command Mode after dialing ! Flash On-Hook @ Quiet Answer +++AT Escape Sequence: Entering Command Mode While On-Line BREAK AT Alternate Escape Sequence: Entering Command Mode While On-Line Refer to Appendix F of this manual for a summary of commands. 3.5 Result Codes You can choose result codes that closely match those of the "Standard AT" command set ("Standard AT" Responses) or enhanced function result codes that have been used in Multi-Tech modems in the past ("Multi-Tech responses"). The &Q command selects which result codes will be used. The 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 monitor or printout. You can choose to have these Result Codes displayed in a "verbose" format (complete words), or in a "terse" format (single digit numbers). The factory default setting is for the verbose format. To change this setting to the terse format, use the V command. You can also choose basic result codes (connect with no speed indication), extended result codes (with speed indication), and whether you want call progress indications (busy and no dial tone) added to the extended result code set. This is controlled with the X command. MT2834MR RESULT CODES CODE DESCRIPTION OK Your command was executed, and the MT2834MR is ready for your next command. CONNECT A carrier signal was detected at 300 bps.* RING A ring signal was detected from an incoming call. NO CARRIER No carrier signal was detected, or the carrier signal was lost. ERROR An error is present in your command sequence, (e.g., invalid character or too many characters). CONNECT 1200 A carrier signal was detected at 1200 bps.* NO DIALTONE** No dial tone was detected, and your modem will not dial.** BUSY** A busy signal at the number you dialed was detected.** NO ANSWER The Remote system did not answer. CONNECT 2400** A carrier signal was detected at 2400 bps.* CONNECT 4800 A carrier signal was detected at 4800 bps.* CONNECT 9600 A carrier signal was detected at 9600 bps.* CONNECT 14400 A carrier signal was detected at 14,400 bps.* CONNECT 19200 A carrier signal was detected at 19,200 bps.* CONNECT 21600 A carrier signal was detected at 21,600 bps.* CONNECT 24000 A carrier signal was detected at 24,000 bps.* CONNECT 26400 A carrier signal was detected at 26,400 bps.* CONNECT 28800 A carrier signal was detected at 28,800 bps.* CONNECT 1275 The modem is connected in V.23 mode. * These responses are used only in the Extended Result Code set, and the CONNECT response will indicate a bps connection. When the Basic Result Code set is used, the CONNECT response can mean either 2400, 4800, 9600, 14,400, 19,200, 21,600, 24,000, 26,400, or 28,800 bps. A connection using error correction will be indicated by the addition of the word LAP-M or RELIABLE (verbose) or the letter L or R (terse) to the CONNECT responses. A connection using MNP5 data compression will be indicated by the addition of the word COMPRESSED (verbose) or the letter C (terse) to the CONNECT responses. ** In the modem's default setting of blind dialing, these responses will not be used. 3.6 Command Mode Fundamentals This section discusses Command Mode fundamentals, Dialing commands, Immediate Action commands (except dialing), and Configuration commands. The rest of the commands are covered in Chapter 5. 3.6.1 Entering and Executing Commands When you type commands for the MT2834MR, each command must start with the Attention Characters AT. Attention characters can be typed in either upper case (capital) or lower case (small) letters. The AT characters alert the modem that a command follows. The Attention command can also be used to clear the command buffer, by typing AT and then hitting ENTER. Typing the AT characters automatically sets the modem's speed to match the speed of your computer or terminal, and also sets the modem's parity. The MT2834MR will not execute a command until you hit ENTER. Therefore, ENTER should be pressed when the entire command has been typed. There are some exceptions to this rule. The A/ (Repeat Last Command) command is executed without hitting ENTER. The A: command is also executed without hitting ENTER. Typing A/ will cause the MT2834MR to repeat the last command that was executed. This last command remains stored in the modem's command buffer until the Attention Command AT is typed. Therefore, AT must not be typed before A/ is typed. The A/ command will have no effect if there is no command stored in the command buffer. It is not necessary to hit ENTER to execute this command. Many MT2834MR commands consist of a letter, followed by a number (0, 1, etc.). If a command like this is typed without the number, the modem will assume that its value is zero (0). For example, if you type ATH as a command without a 0 or 1 following the H, the command will be ATH0. (In this example, the effect is that the modem hangs up.) As you become more familiar with the MT2834MR's commands, you will find yourself taking advantage of this shortcut. 3.6.2 Command Editing You can use the BACKSPACE key on your keyboard to edit characters in the command line. The command will not be executed until you hit ENTER. The BACKSPACE key erases the previous character for retyping. The BACKSPACE key will not erase the AT characters once they are typed. If your keyboard has no BACKSPACE key, CTRL-H will accomplish the same thing. The character recognized by the modem as BACKSPACE may be changed to any other ASCII character with S- Register S5. To cancel an entire command that has been typed but not yet executed, type CTRL-X. This also clears the command buffer. The effect is the same as backspacing to cancel the entire command, only quicker. Characters typed in a command are stored in the MT2834MR's Command Buffer (memory) until executed by hitting ENTER. 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 typing 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 typed, the Command Buffer is automatically erased, and an ERROR message appears. You then retype the command within the sixty-character maximum, using only the allowed characters. Note: In some applications, such as auto-answer only, you may disable the Command mode altogether. When you do this, the MT2834MR ignores all commands, and functions as an auto-answer non-intelligent modem. This is done with DIP-Switch #8 on the modem card (explained in Chapter 7). The factory default setting is Command mode enabled. 3.7 Dialing Commands 3.7.1 Dialing Action Commands D Dial Command The letter D in a command causes the MT2834MR to dial the telephone number immediately following it. For example, if you type ATD5551212 and hit ENTER, the MT2834MR 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, type ATD on your keyboard and hit ENTER. Then hang up the handset. Unless you have a specific need to dial in this manner, we recommend you use the first method, where you type the telephone number on your keyboard. The MT2834MR gives you several choices regarding dialing methods. You can use tone or pulse dialing, by inserting a letter T or a letter P in the command string. (See Section 3.7.2 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 3.9 X Command.) Note: There is another method of dialing, called "DTR Dialing", where by manipulating the DTR signal on pin 20 of the RS232C interface, a number stored in the modem's memory is automatically dialed. See Section 3.9 on DTR Dialing ($D command) for details. A: Continuous Redial (not used in MT2834MRK or MT2834MRI) If you select the Wait-For-Dial-tone method of dialing (see X3 or X4 command), it is possible for you to command the MT2834MR to continuously redial (maximum 10 redials for DOC units) a busy number until your call is answered. This is done with the A: command. This command is used only if you have already reached a busy number after executing a normal dial command. Type A: (you need not type AT, nor do you need to hit ENTER), and the modem redials the number. If you again reach a busy signal, it redials again and again until it no longer detects a busy signal. To stop the redialing, press any key. : Continuous Redial Another way to redial a phone number continuously is to type a colon(:) at the end of the phone number. The result is the same as if you had typed A: after observing that the number was busy on the first dialing attempt. Using the colon in the dial command is a step saver. H Hanging Up, and Bringing the Phone Line Off Hook You can make the MT2834MR hang up (go On Hook), or go Off Hook, with the H command. Type ATH1 to bring the line Off Hook, just as if you had picked up the telephone handset. To hang up, type ATH0 or ATH (remember that the default value is 0 when no number is typed). It is not necessary to type H1 to bring the line Off Hook when using the D command to dial, since the modem will go off hook automatically when you hit ENTER at the end of the dial command. 3.7.2 Dial Modifiers There are several commands 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 Command mode or switching to Answer mode after dialing. P, T Pulse or Tone Dialing The MT2834MR can dial numbers using either pulse or tone dialing, or a combination of both methods. Pulse dialing is the method used by rotary-dial telephones, which involves the timed opening and closing of a line relay. Tone dialing is that used by pushbutton Touch-Tone™ telephones, and is sometimes referred to as DTMF, or Dual-Tone Multi-Frequency dialing. The dialing method is controlled by typing 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, to pulse-dial the number 555-1212, type ATDP5551212 and hit ENTER. To tone-dial the same number, type ATDT5551212 and hit ENTER. If neither Pulse nor Tone dialing is specified in the dial command, the MT2834MR uses whatever method was last used. If the modem has been reset or was just powered up, it uses Pulse dialing, even if you do not include the letter P in your dial command. Nearly all telephone systems in the U.S. are compatible with tone dialing. Since that is the faster method, you will probably use tone dialing. An example of combining pulse and tone dialing could involve a PBX system where 9 has to be pulse-dialed first, then the rest of the number tone-dialed after pausing for a second dial tone. To dial the number, type ATDP9, T5551212 and hit ENTER. (The comma causes a pause, which is explained soon.) &P Set Pulse Dial Ratios The &P command sets the time ratios between the open and closed positions of the dialing pulse frequencies. To set a dialing pulse ratio of 60mSec to 40 mSec, type AT&P0. To set a ratio of 67 mSec to 33 mSec, type AT&P1. The factory default setting is &P0. The &P command is not available on the MT2834MRK. , Automatic Pauses in Dialing You can cause the MT2834MR to pause during the dialing sequence by typing a comma character where the pause is desired. This pause lasts two seconds (4.8 seconds on the MT2834MRK). If a longer pause is desired, more than one comma may be typed consecutively, with each one causing a two second pause. You can also change the length of the pause caused by the comma from 0 up to 255 seconds with S-Register S8 (refer to Chapter 4). Each comma used in a dialing command does count as one of the sixty allowed characters. Y Long Space Disconnect The Y command enables or disables the modem's ability to respond to a long space disconnect condition. The command Y0 disables it (factory default setting) and Y1 enables it. W Wait for New Dial-Tone A W inserted in the dialing command causes the MT2834MR to wait for another dial tone, and the modem will not resume dialing until another dial tone is detected. It is not necessary to type a W at the beginning of the dialing command to wait for a modem dial tone, since the modem will pause automatically. In order for this command to work, you must first select Wait-for-Dial- Tone dialing with the X2 or X4 command, so that your modem can detect the dial tone. ; Returning to Command Mode After Dial Command Execution A semicolon (;), when typed as the last character of a dialing command, causes the MT2834MR to return to Command mode immediately after executing the command instead of waiting for a carrier signal and going on-line. For example, type ATDT5551212; to simply tone-dial the number, and do nothing afterwards except go back into Command mode. This is 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. R Reversing the Mode of Operation In certain applications you may need to reverse the modem's mode of operation from originate to answer, or answer to originate, so that it answers the phone and goes into originate mode, or dials a number and goes into answer mode. This command turns off the reversing function with the R0 command and turn it on with the R1 command. ! Flashing On Hook Some switchboard systems react to a momentary On Hook. An exclamation mark inserted in the dialing command causes the modem to "flash" on hook for a half second, just as if you had held the switch hook on a telephone set down for a half second. (The flash is 90 mSec. on the MT2834MRK.) For example, to flash On Hook after dialing the number 555-1234 in order to transfer to Extension -5678, type ATDT5551234,,!5678. The commas cause a 4 second pause (just to be safe). @ Quiet Answer The @ command causes the MT2834MR 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@7853500 causes the MT2834MR to dial the first number (555-1212) and wait for the time specified in S- Register S7 for at least one ringback and 5 seconds of silence. If a busy signal is detected, the MT2834MR 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 then detected, 785-3500 is dialed. 3.7.3 Phone Number Memory Commands D...N Storing Phone Numbers A telephone number and command line of up to sixty characters may be stored in the MT2834MR number memory. As many as ten of these numbers may be stored. Each number is given a name, using the codes N0 to N9. To store a phone number, type ATD, then the number as it would be dialed along with any P, T, R, ; or , characters, and then type N followed by the phone number's "name," (any number from 0 through 9) and then hit ENTER. For example to store the number 1-612-631-3550 as number N3, type ATDT16126313550N3 and hit ENTER. The number is not dialed with this store command. After storing a phone number, check if it has been stored correctly by typing ATL and hitting ENTER. 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 extended result codes, detect busy/dial tone, error correction, Xon/Xoff flow control, pacing, and data compression, type: ATX4&E1&E5&E13&E15DT16126313550N3. N Dialing a Stored Number To automatically dial a telephone number that you a have stored in the MT2834MR number memory, type ATNn (where n = 0 through 9). For example, to dial a number stored at N3, type ATN3 and hit ENTER. Do not include the letter D in this command, or the stored number is erased. NN Number Linking You may cause the MT2834MR to dial a second number automatically if the first number you dialed is busy. This is useful in a situation where a computer can be accessed through more than one phone number. This is called "linking". To link the number at N1 to the number at N2, type ATN1N2 and hit ENTER. Several numbers can be linked in the same command. For example, to link N1 to N2 to N3 to N4, or link N1 to N2 and back to N1 and then back to N2, type ATN1N2N3N4 in the first example, and ATN1N2N1N2 in the second example. The only limit to 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 to use the Number Linking feature. Note: The NN command is not used in the MT2834MRK. L Listing Numbers Stored in Memory Telephone numbers stored in the MT2834MR's memory may be listed and displayed with the L command. It displays all ten stored numbers in a format like that shown below. All digits and command letters are shown. The number's "name" (0 thru 9) is shown first, followed by the complete dialing command and telephone number as originally typed. Type ATL and hit ENTER to display these numbers on your video screen or printout. 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 ATX4&E1E5&E13&E15DT16126313550N3 9 T12138880123 3.8 Immediate Action Commands $H Help Screens The $H command gives you short explanations on how to use each MT2834MR command. The $H command can be quite useful if your manual is not handy and you are in the middle of a communications session. Although the explanations are quite abbreviated compared to those in this manual, they should prove to be helpful reminders when needed. At the time of this writing, we have three screens of Help information (Screen #1, #2 and #3), and more screens may be added in the future. The Help commands are structured so that you can call up one of three Help screens, as follows: AT$H1 = Help Screen #1 AT$H2 = Help Screen #2 AT$H3 = Help Screen #3 +++AT Escape Sequences -- Entering Command Mode While Still On-Line It is possible to cause the MT2834MR to enter the Command mode after the modem has gone on-line with a remote modem, without disconnecting the call. This is accomplished by typing an Escape Code. The default Escape Code used by the MT2834MR is three plus signs (+++) followed by the letters A and T, up to sixty command characters (most typically H, to hang up), and an ENTER. 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 will escape to Command mode, execute the command (if any), and then remain in Command mode. For example, to hang up the modem at the end of a call, the command would be +++ATH followed by ENTER. There is no need to incorporate pauses before and after the plus signs, as done in earlier modems. BREAK AT The MT2834MR provides an alternative Escape method, using a Break signal as the Escape Code. The Break signal 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 ENTER. When this is done, the modem will execute that command, but remain in the normal 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 ITU-T 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. ITU-T publications can be obtained from Omnicom, Inc., 112 Park Street SE, Vienna, VA 22180, Phone 703/281-1135, FAX 703/281-1505. %E Escape Sequence Options -- Entering Command Mode While On-Line As mentioned, the default setting is for the modem to respond to the +++ escape method. Optional settings are for the modem to respond to the BREAK method, for the modem to respond to either the +++ or the BREAK Methods, and for the modem to ignore both methods and not escape. The %E command is used to select these options, as follows: %E0 = Modem Won't Escape %E1 = +++AT Method (factory default setting) %E2 = BREAK Method %E3 = Either +++ or BREAK Methods %E4 = Disable OK response to +++ %E5 = Enable OK response to +++ Note: The Escape Code for Remote Configuration (see Appendix K) has %%%AT for the factory default setting. O Exiting Command Mode, Going Back On-Line To bring the MT2834MR out of Command mode back into On-Line mode, type ATO (where O is the letter O, not the number 0). In this case, the O command reverses what was done by typing the Escape Code. The O command places the modem in the same On-Line mode (Originate or Answer) that it was in prior to going into Command mode. A Forcing Answer Mode With the A command you can force the MT2834MR into the Answer mode. Type ATA Mode when in Command mode to immediately bring your modem off-hook, out of Command mode and into the On-Line Answer mode, and cause it to transmit its carrier signal over the phone line. If no responding carrier tone is received by your modem within 45 seconds (or some other time as determined by S-Register S7), your modem will cease transmitting its tone, hang up, and go back into Command mode. I Inquiry for Product Code Some systems or software packages automatically check the "Identification" of the modem with which they are communicating, by using the I command. This "read" command lets the software determine the type of modem with which it is communicating. When ATI or ATI0 is typed, the MT2834MR responds with 247. When ATI1 is typed, the modem responds with a three-digit firmware version number. L5, L7 Listing Current Operating Parameters The L5 and L7 commands allow you to list the current operating parameters of your modem. This information can be very useful when reconfiguring your modem, such as when you are changing communications software or when you are changing your factory default settings. To list the MT2834MR's current operating parameters, type ATL5 for the basic parameters. Type ATL7 to list additional parameters. The parameters for all of the configuration commands (covered in section 5.9) are listed. L6 Listing S-Register Values The L6 command lists the current values stored in the modem's S- Register. This information can be very useful if you wish to change S- Register values. (Refer to Chapter 4 for more information on S- Registers.) L8 Listing On-Line Diagnostics The L8 command displays the current on-line CONNECT status of the MT2834MR. 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 type +++AT (on-line escape command while maintaining command mode), then type ATL8. 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.) is displayed. 3.9 Configuration Commands 3.9.1 Configuration Storage and Default Commands &F Loading Factory Defaults Because the modem has the capability of storing reconfigured parameters and S-Register values into its non-volatile Random Access Memory (RAM), you may wish to have a choice between these RAM stored parameters and values or the factory default parameters and values (as determined by the modem's ROM and DIP-Switches). The &F command lets you set the modem to the factory defaults in ROM. The modem will then ignore the parameters and values that remain stored in RAM. The command AT&F causes the MT2834MR to use the factory default setting ROM configuration parameters and S-Registers values. To replace the parameters and values stored in RAM with all factory default settings, combine the &F and &W commands by typing AT&F&W and hitting ENTER. The &F8 and &F9 commands determine the function of the &F command. If you type the &F8 command (the factory default setting), and later type a subsequent &F command, the modem reads the factory default settings, regardless of what is stored in non-volatile RAM (defined by the &W command). If you type the &F9 command, and then type a subsequent &F command, the modem reads the parameters and values stored in non- volatile RAM as the defaults. The result is that the setting of the &W command defines the source of the default parameters and values that your modem reads as its factory default settings. &W Storing Configuration & S-Register Parameters in the Modem's Non-Volatile Memory The MT2834MR can store its configuration parameters and S-Register values in its non-volatile read/write (RAM) memory. Type the &W command to store parameters and S-Register values in the modem's RAM, and to prevent any reconfiguration from being lost on a power-down or Reset (ATZ) condition. Type AT&W0 (or AT&W) to cause the modem to store its current parameters and values in its non-volatile RAM. This command also sets the modem so that when it is powered up, or when it is reset with the ATZ command, the modem will read all of its configuration and S- Register parameters from RAM, and not from the factory default setting in ROM. Type AT&W1 to set the modem so that it does not store its parameters to RAM, and, when a subsequent power on condition or ATZ command is executed, parameters will be read from the factory default settings in ROM and from the DIP-Switch settings. Z Modem Reset Type the Z command to reset all MT2834MR configurations to their factory default settings, and to clear the Command mode buffer. When you type ATZ, the result is the same as if you had disconnected, and then reconnected power to the modem. When the 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.) 3.9.2 Command/Response E Echoing Command Mode Characters If the MT2834MR is connected to a full-duplex terminal or computer, you may have to configure the modem to echo back characters typed while in 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. Q Result Codes (Enable or Disable) and No Response Answer The Q command enables or disables Result Codes and the No Response Answer mode of operation. Regarding Result Code Enable/Disable, you may want to disable the Result Codes altogether in certain applications, such as computer- controlled autodialing. The command ATQ1 disables Result Code transmissions and ATQ0 (or ATQ) enables them. In typical operation, the originate mode and answer mode are "intelligent" operations, controlled by the position of the modem DIP-Switches and previously executed commands. Regarding No Response Answer, you may want Answer mode handled without responses, and echo turned off but want 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 enables the Result Codes to be sent. &Q Result Codes - "Multi-Tech" or "Standard" The MT2834MR modems give you a choice between Multi-Tech responses (which include RELIABLE and COMPRESSED responses), and a set that more closely matches the Standard AT command set result codes. AT&Q0 selects Multi-Tech responses with Reliable/Compression modifiers, DIALTONE/BUSY/NO ANSWER. With this setting, the terse response for CONNECT 2400 is 9. This is the factory default setting. AT&Q1 selects Standard AT responses with no Reliable/Compression modifier. With this setting, the terse response for CONNECT 2400 is 10. Refer to Appendix D for a summary of Result Codes. V Result Codes - Word or Digit The V command controls whether the MT2834MR's result codes are displayed as words ("verbose") or single digits ("terse"). For example, if after dialing, no carrier signal is detected, the result can be displayed either as NO CARRIER, or as the digit 3. Type ATV0 (or ATV) to cause the MT2834MR to display the Result Codes as digits. Type ATV1 to display the Result Codes as words. If you do not select a method, the factory default setting will cause the modem to use verbose results. X Result Codes (Basic or Extended) and Call Progress Method The X command selects both the dialing method ("dumb" or "smart"), as well as various response combinations related to the dialing method selected. Regarding result code selection, you can choose to have certain responses suppressed, and whether or not you want speed indications along with the CONNECT responses. The MT2834MR 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 (CONNECT, CONNECT 1200, CONNECT 2400 and CONNECT 9600). Regarding the method of dialing, the MT2834MR 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 MT2834MR 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. The MT2834MR gives you a choice between the wait-for-dial-tone ("smart") dialing 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 effects on the MT2834MR's result code set. 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 select "smart" dialing methods 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 for dial tone. X4 Looks for dial tone and for busy. The factory default setting is X4, which selects extended and "smart" result codes. 3.9.3 RS232 Interface Commands &C Carrier Detect Control The &C command lets you control the status of the Carrier Detect signal (CD - Pin 8) on the RS232C interface. You have three choices. You can force the signal high, allow it to act normally, or set it up so that it will 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, type the command AT&C1 (this is the factory default setting). To force CD on, type the command AT&C0. To set up CD so that it drops for one second on disconnect and then comes up again, type 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 Chapter 4 for S24 instructions.) &D Data Terminal Ready Control Data Terminal Ready (DTR) on pin 20 of the RS232C interface is required for the MT2834MR to operate. A high DTR signal 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, 12-position DIP-Switch #1 can be used to force the DTR signal on. DTR can also 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, type the command AT&D3 and hit ENTER. 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. Type AT&D0 or AT&D to cause the MT2834MR to ignore DTR. Type AT&D1 to cause 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. Type AT&D2 to cause the modem to go on hook with loss of DTR. The modem enters Command mode when DTR goes high again. &R Clear to Send Control The &R command lets you control the status of the Clear to Send signal (CTS - Pin 5) on the RS232C interface. You have three choices. You can force the signal high, allow it to act normally, or set it up so that it will 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 CTS to act in this manner. To allow CTS to act normally, type AT&R0. To force CTS on, type AT&R1 (when the modem goes on-line, CTS still provides flow control). Type AT&R2 to set up CTS so that it drops for one second on disconnect and then comes up again. (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 4 instructions for S24.) If you type the &R2 command, be sure that the CTS DIP-Switch on the modem circuit board is set to allow CTS to act independently of Request to Send (RTS). (Refer to Chapter 7 for details.) &RF CTS/RTS Interaction Conrol In typical operation, Clear to Send will follow Request to Send when the modem is on-line. In other words, if RTS goes off, CTS goes 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. Refer to the &R command for control of Clear to Send functionality. The factory default setting is &RF1. &S Data Set Ready Control The &S command lets you control the status of the Data Set Ready signal (DSR - Pin 6) on the RS232C interface. You have three choices. You can force the signal high, allow it to act normally, or set it up so that it will 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, type AT&S1 (this is the factory default setting). To force DSR on, type AT&S0. To set up DSR so that it drops for one second on disconnect and then comes up again, type 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 4 instructions for S24.) If you type the &S2 command, be sure that the DSR DIP-Switch on the modem circuit board is set to allow DSR to act independently of Carrier Detect (CD). Refer to Chapter 7 for details. &SF DSR/CD Interaction Control In typical applications, Data Set Ready (DSR) will follow Carrier Detect (CD). &SF0 enables DSR to follow CD, and is the factory default setting. &SF1 enables DSR to operate indepent of CD. If this is the case, refer to the &S command for control of Data Set Ready functionality. 3.9.4 Phone Line Conditioning Commands #A Auto Speed Detect The #A command lets you select operation as either a 9600/4800 bps ITU-T V.32 standard modem, a 2400 bps ITU-T V.22 bis (Bell 2400) standard modem, a ITU-T V.22/Bell 212A (1200 bps) modem or a Bell 103/113 (300 bps) modem. The function of the #A command is to detect and select the operational baud rates which the MT2834MR will use for initial handshake and speed selection. Note: The #A command does not control the originating bps rate of the modem (that is done by the Modem Baud Rate command $MBXXXX), but only answer mode fallback speeds. Type AT#A0 (or AT#A) to cause the MT2834MR to operate starting at 28,800 bps with fallback to 19,200 to 14,400 to 9600 to 4800 to 2400 to 1200 to 300 bps. AT#A1 uses 28,800 bps only. The AT#A2 causes the modem to operate at starting speeds of 28,800 bps, with incremental fallback to 19,200, 14,400, 9600, and 4800 bps. The AT#A3 command causes the modem to begin operation as a V.22bis modem at 2400 with fallback to 1200 to 300 bps. AT#A1 is the factory default setting. &L Leased Line (2/4 wire, Answer/Originate) Mode Select The &L command lets you select one of four modes of MT2834MR leased-line operation. You can select any combination of 2- or 4-wire operation in Answer mode or Originate mode. The factory default setting (on power up) is &L0 (dial-up mode operation). Type AT&L1 to allow just one attempt at a leased line connection. Type AT&L2A for 2-wire operation in Answer mode. Type AT&L4A for 4-wire Answer mode operation. Type AT&L2D for 2-wire Originate mode operation. Type AT&L4D for 4-wire Originate mode operation. Note: You must include the A or the D command in the dialing string with the &L command. The &L command is intended for use by the MultiModemManager administrator. MT2834MR power must be cycled to clear the &L command. The &L command is not stored in modem memory. DIP- Switch #10 in the UP position (Dial-Up Operation) overides the &L command (refer to Chapter 7 of this manual). B Bell or ITU-T Tone You can use the B command to select the frequency that the modem uses for its answer tone. (The 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 14.4k bps) there is no conflict, because all use ITU-T frequencies. At lower speeds (0-1200 bps), in the U.S., some modems use the Bell frequency of 2225 Hz. However, the ITU-T specification for V.22bis has an answer tone frequency of 2100 Hz. The ATB0 command enables the ITU-T answer tone. The ATB1 command enables the Bell answer tone. The factory default setting is ATB0 (ITU-T tones). This B command is not available on the MT2834MRK. $D DTR Dialing An alternate way to cause the MT2834MR to automatically dial is "DTR Dialing". The Data Terminal Ready (DTR) signal comes into the modem from the attached terminal or computer, on pin 20 of the RS232 interface. With DTR dialing, the modem automatically dials a stored number as soon as it receives a high DTR signal. The DTR dialing method is popular when using the MT2834MR in synchronous applications. To enable DTR Dialing, type AT$D1 and hit ENTER. The modem will dial the phone number you have stored at N0 when it receives a high DTR signal (see Section 3.7.3). DTR must remain high for the duration of the call (until disconnect). To disable DTR dialing, type AT$D0 (or AT$D) and hit ENTER. When you use DTR Dialing, be sure that 12-Position DIP-Switch #1 is in the UP position, so that DTR is not forced on. (Refer to Chapter 7.) #F Fallback Modes When On-Line If the line conditions deteriorate, the MT2834MR automatically drops its transmission speed (fallback). The #F command controls the different ways that the MT2834MR 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 28,800 bps operation, the modem initiates a retrain at 4800 bps. If after the first retrain the modem returns on-line at 28,800 bps, the modem starts a counter and a timer. If three retrains occur within a two minute period, the modem falls back to 4800 bps. Type AT#F0 (or AT#F) will cause no fallback when on-line. Type AT#F1 to cause the MT2834MR to fall back (based on the error rate or if three retrains have occurred within a two minute period) from 28,800 to 26,400 to 24,000 to 21,600 to 19,200 to 16,800 to 14,400 to 12,000 to 9600 to 4800 bps. The AT#F2 command enables incremental fallback from 28,800 bps to 4800 bps, but also enables fall forward (from 4800 bps to 28,800 bps incrementally) if the phone line improves. AT#F2 if the factory default setting. &G Guard Tones You can use the &G command to control the presence or absence of guard tones from the transmitter when in Answer mode, at either 1200 or 2400 bps. Guard tones are used in Europe and other areas, in order for the modem to function in the telephone systems. Guard tones are not used in the United States. AT&G0 turns off the guard tones, and is the factory default setting. AT&G1 turns on a 550 Hz guard tone. AT&G2 turns on an 1800 Hz guard tone. The &G command is not used on MT2834MRK units. $MI MI/MIC Control The $MI command enables and disables the mode indicate/mode indicate common interface function. AT$MI1 enables MI/MIC operation and AT$MI0 disables it. With the MI/MIC option enabled, the modem's A and A1 telephone line interface output leads are replaced with MI and MIC input leads. (Tip and Ring remain unaffected.) When MI and MIC are connected together, the modem goes Off Hook in Originate mode, for a time period specified by the modem's Abort Timer (S-Register S7). For example, a 45 second Abort Timer means that if the modem does not detect a carrier tone within 45 seconds after it goes Off Hook, it will disconnect. The $MI command is not available on the MT2834MRK. NOTE: This option is a hardware modification that must be ordered separately; it is not automatically included with the MT2834MR modems. &T Enable or Disable Recognition of Remote Digital Loop Signal The MT2834MR has several test features, which are covered in detail in Chapter 6. The tests are activated with different U commands, such as ATU0, ATU1 and so forth. There is one command, however, that is really a configuration command, so we will cover it here. That is the &T command, which enables or disables the modem's ability to recognize the Remote Digital Loop (RDL) test signal. The command AT&T4 allows the MT2834MR to respond to a RDL signal, and place itself in digital loop. The command AT&T5 disables this capability, meaning that the modem will ignore the RDL signal. (Refer to Chapter 6.) #T Enable/Disable Trellis Coded Modulation The #T command enables or disables Trellis Coded Modulation for the MT2834MR. There is usually no need to disable (turn-off) Trellis Coded Modulation except under an unusual line condition called impulse noise. The command AT#T0 turns off Trellis Coded Modulation and AT#T1 turns it on. The factory default setting is AT#T1. 3.9.5 Miscellaneous Commands &A Answerback The &A command controls the MT2834MR's Answerback feature. Answerbacks are used in some on-line realty applications, and elsewhere, as a security measure. Due to the security aspect of this feature and the fact that there is no requirement for the user to do anything with the modem, we will not discuss Answerback here, other than to say that it exists and that we recommend you avoid &A in any commands or programming. &B Transmit Buffer Size The size of the transmit buffer size is controlled with the &B command. It may be desirable to reduce the size of the transmit buffer for certain applications. For example, when your modem is receiving a long stream of data and the modem at the other end is using speed conversion (the serial port speed is greater than the modem baud rate). If you wanted to interrupt the current data and request data from a new source, you may have to wait for data in the buffer of the sending modem to empty. By reducing the transmit buffer size of the sending modem, this wait will be reduced. Using the reduced buffer size may cause a slight loss in data throughput. AT&B0 = Normal transmit buffer size AT&B1 = Reduced transmit buffer size The factory default setting is &B0 $EB Asynchronous Word Length Command The MT2834MR has an 11-bit capability when operating asynchronously. The $EB command selects between 11-bit and 10-bit operation. Type AT$EB1 to enable the modem to function in an 11-bit (one start bit, eight information bits, one parity bit and one stop bit) format. Type $EB0 (the default setting) to enable a 10-bit (one start bit, seven information bits, one parity bit and one stop bit) format. $EB is functional in both Command and On-line mode. $EB0 automatically detects parity when an AT command is issued. &M Synchronous/Asynchronous Mode Switching The &M command is used to set the on-line mode of the MT2834MR to either Synchronous or Asynchronous. AT&M0 sets the mode to Asynchronous, and all communications will be Asynchronous, both in On-line and Command mode. AT&M1 causes the MT2834MR to communicate asynchronously when in Command mode, and to switch to synchronous mode while on-line. The factory default setting is &M0. &X Synchronous Transmit Clock Select The &X command selects the Synchronous Transmit Clock Source. External clocking is when the DTE provides transmit clocking to the modem on pin 24 of the RS232C interface. Internal clocking is when the modem provides transmit clocking to the DTE on pin 15 of the RS232C interface. Internal clocking (&X0) is the factory default setting. The command &X2 selects Slave (External) Clocking. The &X2 command causes the MT2834MR 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 Slave mode, all timing is controlled by the receive clock. The position of pin 3 is insignificant when in Slave mode. $AS AS/400 Support The MT2834MR has the ability to function in an IBM AS/400 environment. The $AS1 command enables AS/400 mode, and causes the MT2834MR function with the IBM command set. The $AS0 command disables this function. Note: The MT2834MR must have Command mode and Synchronous mode enabled to allow AS/400 mode to be selected. The factory default setting is AS/400 mode disabled ($AS0). $SP UNIX UUCP Spoofing The MT2834MR can be configured for a UNIX environment that employs ACK flow control as a means of monitoring data integrity. The modem can perform UUCP "spoofing", where the MT2834MR can generate ACKs at the DTE interface. Data is transmitted more time effectively because the delay of waiting for data to be received, then for an ACK to be returned at the remote end, is eliminated. Type $SP1 to enable UNIX UUCP spoofing. Type $SP0 to disable UNIX UUCP spoofing (the factory default setting). For more information on the UUCP (UNIX-to-UNIX Copy Program) function, refer to your UNIX system documentation. &I Inactivity Direction You may use the &I command in conjunction with S-Register S30 to select how the Inactivity Timer will work in your modem. &I controls the direction of the inactivity. S-Register S30 controls the duration of the inactivity. You may turn off the Inactivity Timer, or set the modem to respond to inactivity only when receiving, or only when transmitting, or to respond to both receiving and transmitting. &I0 The Inactivity Timer is turned off. &I1 The Inactivity Timer resets when data is received from the other modem. &I2 The Inactivity Timer resets when the modem transmits. &I3 The Inactivity Timer resets when data is either transmitted or received. The factory default setting is &I0. *C Caller ID Detection Note: The Caller ID detection feature is optional. The Call Traffic window will display the phone number and the name of an individual that dials in on a phone line that supports Caller ID. The call must not be answered before the second ring to receive this information. This feautre requires a modem hardware upgrade, Caller ID phone lines, and a firmware level greater than 8.07a or 2.07a. The Caller ID firmware is inactive by default, but can be activated via the modem AT command, *C. *C0 Turn off Caller ID detection. *C1 Turn on Caller ID detection for the MultiModemManager. *C2 Turn on Caller ID reporting on the serial port by the MultiModemManager. The factory default setting is *C0. 4.1 Introduction This chapter covers MT2834MR software registers called S-Registers, where certain MT2834MR modem and Command mode configurations are stored. Each S-Register is assigned a number (S0, S1, S2, etc.). Use the S command to read and/or change the value stored in an S-Register (ATSr? to read and ATSr= to change S-Register values). Refer to Section 4.2, Reading and Assigning S-Register Values. S0 Number of Rings until Modem Answers Unit: 1 ring Range: 0-255 Default: 1 Description: S0 defines the number of rings the modem waits before answering an incoming call. The default value is one ring (Decimal 1), which means that the modem answers the call immediately after the first ring. The maximum number of rings that can be configured is 255. Setting the value to zero (0) disables auto-answer completely. S1 Rings which have Occurred Unit: 1 ring Range: 0-255 Default: 0 Description: S1 counts the number of rings that have occurred. It is a "read" type of register and is seldom, if ever, used in typical operation. Each time an incoming ring signal is detected, S1 increases its value by one, up to a maximum of 255. If you set S1 to a value other than its default value of zero, or if the value is increasing with rings, this new value remains stored in S1 for eight seconds after the last ring is counted, after which time the value reverts back to zero. S2 Escape Code Character Unit: ASCII Range: 0-127 Default: 43 (+ sign) Description: S2 defines the escape code character. The default character is the plus (+) sign (Decimal 43). It may be set for any ASCII character. Setting an S2 value greater than 127 results in no escape character, and therefore no means of entering Command mode from On-line mode without breaking the on-line connection. S3 Return Character Unit: ASCII Range: 0-127 Default: 13 Description: S3 defines the character recognized as Carriage Return (ENTER) or Return. The default setting is CTRL-M (Decimal 13), which is the ASCII code for the ENTER key on most keyboards. S3 may be set for any ASCII character. S4 Line Feed Character Unit: ASCII Range: 0-127 Default: 10 Description: S4 defines the character recognized as Line Feed. The default setting is CTRL-J (Decimal 10), which is the ASCII code for the Line Feed key on most keyboards. S4 may be set for any ASCII character. S5 Backspace Character Unit: ASCII Range: 0-127 Default: 8 Description: S5 defines the character recognized as BACKSPACE. The default setting is CTRL-H (Decimal 8), which is the BACKSPACE key on most keyboards. S5 may be set for any ASCII character. S6 Wait Time for Dial Tone Unit: 1 sec. Range: 2-255, 4-7* Default: 2, 4* Description: S6 sets the time the modem waits after the ENTER key is pressed before executing a dial command. The default setting is two seconds (Decimal 2) or four* seconds. S7 Time for Carrier (Abort Timer) Unit: 1 sec. Range: 1-255, 1-45* Default: 45 Description: S7 defines the Abort Timer (lack of carrier) delay time. The default value is 55 seconds (Decimal 55). This means that, after dialing, the modem waits for a carrier signal for up to 55 seconds and, if none is detected, aborts the call. The maximum S7 value is 255 (or 45*) seconds. S8 Pause Time for Comma Unit: 1 sec. Range: 0-255, 4-7* Default: 2, 4* Description: S8 sets the length of the pause caused by a comma inserted in a dialing command. The default setting is two seconds (Decimal 2) or four* seconds, where each unit is one second. S8 may be set for up to 255 seconds. S8 also sets the time the modem waits before retrying a call after detecting a busy signal. Some computer systems need more than two seconds to reset (in which case you should increase the value of S8). S9 Carrier Detect Response Time Unit: 100 mSec. Range: 1-255 Default: 6 Description: S9 sets the time delay between when the modem first detects a valid incoming carrier signal and when the modem turns on its Carrier Detect circuit. The default setting is 600 milliseconds, or six units of 100 mSec each (Decimal 6). S9 may be set for up to 25.5 seconds. S10 Carrier Loss Disconnect Delay Time Unit: 100 mSec. Range: 0-255 Default: 7 Description: S10 sets the time a carrier signal must be lost before the modem disconnects. S10 can only be set at speeds of 2400 bps or less. The default setting is 700 mSec, or seven units (Decimal 7) of 100 mSec. Maximum delay is 25.4 seconds (Decimal 254). Setting the S10 value to 255 causes the modem to not disconnect with loss of carrier. S11 Tone Dialing: Tone Spacing and Duration Unit: 1 mSec. Range: 1-255, 80-255* Default: 70, 80* Description: S11 sets the speed of tone dialing (spacing and tone duration times). The default value is 70 units (Decimal 70) or 80* units, where each unit is one mSec, meaning that each tone is on for 70 mSec with a 70 mSec pause between each. The minimum S11 value allowed by most telephone systems is 50 mSec (50 units). Very few telephone systems can handle anything faster than that. The maximum S11 value is 255 mSec (255 units). S13 Remote Configuration Escape Character Unit: ASCII Range: 0-127 Default: 37 (% sign) Description: S13 defines the remote configuration escape character (which becomes your modem's remote configuration character). The default is three percent symbols (%%%). When the S13 character is entered three consecutive times from a remotely connected site, your modem responds with its Remote Configuration procedure. S17 Changing Break Time Unit: 10 mSec. Range: 0-2500 mSec Default: 250 mSec. Description: S17 defines the break time (space) to the PC. Break duration is adjustable. The break time is changed in 10 mSec increments by increasing or decreasing the value of S17. S18 Automatic Leased Line Restoral Unit: 30 min. Range: 10-255 min. Default: 30 min. Description: When the MT2834MR is in the dial back-up mode of operation, it will periodically check the leased line to see if it's operational and try to restore the leased line if possible. The frequency of restoral attempts is defined by the contents of S-Register S18. The default for S18 is 30 minutes and can be set in one minute increments from 10 to 255 minutes. Setting the restoral frequency to a value less than 10 minutes causes excessive breaks in the dial-up operation. S19 Dial-Back Timer Unit: 1 min. Range: 0-255 min. Default: 1 min. Description: S19 is a timer that starts when the leased line goes down and the modem has determined that the line is bad. When the set time is reached, the originate modem dials the answering modem. The answering modem uses this same timer to determine when it will accept the ring. S24 PBX/CBX Disconnect Drop Time for DSR/CTS/CD Unit: 50 mSec. Range: 0-255 Default: 20 Description: Some PBX and CBX phone systems require the modem's DSR, CTS, and/or CD signals to behave in a certain manner when calls are disconnected. The MT2834MR's &R, &S, and &C commands cause the modem to drop these signals for a specified time period upon disconnect, and then bring the signal(s) up again. S24 defines the length of time that the signals drop. The default setting of 20 results in a one second drop time, which is what most PBX/CBX systems with this requirement need. S25 DTR Dropout Time Unit: 100 mSec. Range: 0, 1 through 255 Default: 0 Description: S25 defines the amount of time that DTR must be dropped before the modem disconnects. Normally, a disconnect occurs when DTR is dropped for 50 milliseconds or more. The S25 unit value for zero is the default value of 50 mSec. For values from 1 through 255, the unit value is 100 mSec. S30 Inactivity Timer Unit: 1 min. Range: 0-255 Default: 0 Description: S30 causes the modem to disconnect if no data is transmitted or received for a specified time. This timer runs during both Reliable and Normal connections. The timer restarts any time a data character is passed through the serial port (either sent or received). If noise on the phone line causes an error to be received during Normal mode, this also restarts the timer. The inactivity timer is disabled by setting S30 to 0, which is the factory default setting. S32 Time Elapse for Escape Sequence Unit: 100 mSec. Range: 0-255 Default: 20 Description: S32 sets the time period to validate the escape sequence. If the time interval expires before the escape sequence is employed (by hitting ENTER), the escape sequence is aborted. The default is 20 units (one second). S34 Buffer Length of Command Mode after On-line Escape Sequence Unit: ASCII Range: 0-60 Default: 10 Description: If the number of characters after AT exceeds the S34 buffer length value, the buffer is cleared and the escape sequence is aborted. S36 DTR Busy-out Time Length Unit: 1 sec. Range: 0-255 sec. Default: 0 sec. Description: S36 sets the amount of time (in seconds) that the modem waits when DTR goes off, before going off hook (busy). S37 DTR Busy-in Time Length Unit: 1 sec. Range: 0-255 sec. Default: 5 sec. Description: S37 sets the amount of time (in seconds) that the modem waits when DTR comes back on, before going on hook. 4.2 Reading and Assigning S-Register Values The S command reads and assigns S-Register values. To read an S- Register value, type the letter S followed by the S-register number and a question mark (?), then hit ENTER. For example, typing ATS7? and hitting ENTER displays the value of S-Register S7 in a 3-digit decimal form. The number 8 appears as 008, the number 30 appears as 030, and the number 255 appears as 255. Convert all ASCII characters to their decimal equivalents before entering them. S-Register decimal values range from 0-127 for ASCII characters, or 0-255 for numeric values. A complete ASCII conversion chart is located in Appendix A of this manual. 4.2.1 Examples of Assigning Values 1. Let's say you wish to have longer pauses caused by the comma in a dial command; five seconds instead of two. Typing ATS8=5 assigns 5 as the value for S-Register S8 (meaning the modem pauses five seconds for a comma in a dial command). 2. In a second example, let's say that you wish to configure the MT2834MR modem to answer incoming calls after the 30th ring instead of after the first ring. To configure S-Register S0 with a value of 30, type ATS0=30 and hit ENTER. 4.2.2 Examples of Reading Values To verify that you entered the value correctly in the above examples, type ATS8? and hit ENTER in the first example and ATS0? in the second example. You should receive the response 005 in the first example and 030 in the second example. Type ATL6 to list all S- Registers and their values. When configuring the S-Registers, it is a good practice to include the verification read-entry in the same command line as the configuration assignment-entry. In the preceding examples, type ATS8=5S8? and ATS0=30S3?. 4.3 AT Commands that Affect S-Registers Your MT2834MR's default configuration is originating a call to another 28,800 bps modem that supports error correction, data compression, and flow control ("maximum throughput"). If the receiving modem is not compatible, the MT2834MR can match any ITU-T or Bell Standard modem (but not proprietary protocols). You may, however, have applications where you do not want this kind of maximum throughput (e.g., service not supporting error correction, or the V.42 handshake interferes with logon sequence). If so, configure the MT2834MR as strictly an auto-answering device or perhaps to function in a UNIX environment. The &W command, used in conjunction with specific other AT commands and S-Registers, reconfigures the MT2834MR to conform to a specific application. An example of the &W command: AT&E2$SP1#L3$R0$MB19200$SB115200$EB1S0=10&W0 The MT2834MR stores its configuration parameters and S-Register values in its nonvolatile memory. The &W0 command stores current parameters and values in its nonvolatile RAM. This command also sets the modem so that on power up, or when reset with an ATZ command, the modem reads all its configuration and S-Register parameters from RAM, and not from the factory settings in ROM. The &W command changes the configuration parameters stored in RAM that you specifically intend to alter. All other default parameters remain unchanged. The &W1 command sets the modem so that it does not store parameters to RAM and, on power up or when an ATZ command is entered, parameters are read from the factory default settings in ROM. Before using the &W command, view the modem's current operating parameters. Use the L5, L6, and L7 commands to display the current modem configuration. 4.4 Summary V.42 error correction is built into the MT2834MR's hardware, detecting and correcting virtually 100% of transmission errors (usually caused by noisy phone lines). When errors are detected, the V.42 protocol causes the modem to retransmit the data block in which the error was found. V.42bis and MNP 5 data compression features are built into the MT2834MR's hardware, providing a higher data throughput than the modem's modulation speed. The throughput increase depends on the type of data transmitted. The MT2834MR also supports ITU-T 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 MT2834MR is set for one of three different modes of operation, along with activating data compression in Reliable mode. Normal mode (&E0) disables error correction, Reliable mode (&E2) turns it on, and Auto-Reliable mode (&E1) lets the modem automatically turn V.42 on when it detects its use in another modem. Flow control methods are used by the MT2834MR to prevent data loss from buffer overflow. The modem both initiates flow control and responds to pacing, using either Xon/Xoff commands or RS232C/V.24 signaling via CTS (from the modem) or RTS (from the computer/terminal). Hewlett-Packard ENQ/ACK is also supported. If needed, Xon/Xoff commands are passed through the modem to a remote computer or terminal. The MT2834MR's speed conversion feature lets the modem operate at one speed over the telephone line and another speed over the RS232C/V.24 serial port. This lets the computer communicate with the modem at a fixed speed of up to 115,200 bps, while the modem operates at various rates of up to 28,800 bps (V.34 enabled). This ability is vital for data compression, since your computer must send data to the modem at a higher speed than the rate at which the modem is sending data over the phone line.