Hayes Modem Technical Reference Technical Reference for Hayes(TM) Modem Users 5 June 1991 Version 1.0b Hayes Microcomputer Products, Inc. P.O. Box 105203 Atlanta, Georgia 30348 Notice: Hayes Microcomputer Products, Inc. (Hayes) provides the information contained in this document to you for your convenience. Hayes does not guarantee the accuracy of the information and reserves the right to change this document, as well as the hardware and software products described herein at any time without notice. The Hayes Standard AT Command Set is proprietary to, and subject to the copyrights of Hayes Microcomputer Products, Inc., and distribution of this document in no way represents a waiver of those rights. Hayes, the Hayes logos, Smartcom, Smartcom II, Smartcom III, Smartcom EZ, V-series, Smartmodem, ULTRA, and ESP are trademarks of Hayes Microcomputer Products, Inc. Other trademarks identified in this document are trademarks of their respective companies. Note: This version of the "Technical Reference for Hayes Modem Users" is a special version edited for bulletin-board downloading. As a plain ASCII character file, it therefore cannot contain any of the illustrations and graphic elements provided in the printed version. To highlight the start of Chapters, 1st Level Heads, 2nd Level Heads, and Tables, we've used the following scheme: Chapters are preceded by: ============================================================================= 1st Level Heads are preceded by: ***************************************************************************** 2nd Level Heads are preceded by: +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 3rd Level Heads are preceded by: ............................................................................. Table heads are separated from table listings by: ----------------------------------------------------------------------------- Document 44-00012 AA K10 (BBS Version) 1990 Hayes Microcomputer Products, Inc. All rights reserved. Table of Contents Chapter One: The Hayes Standard AT Command Set 1.1 AT Command Listing A -- Answer Command B -- Select Communication Standard C -- Carrier Control Selection D -- Dial Command (and dial modifiers) E -- Command State Character Echo Selection F -- On-line State Character Echo Selection H -- Hook Command Options I -- Internal Memory Tests L -- Speaker Volume Level Selection M -- Speaker On/Off Selection N -- Negotiation of Handshake Options O -- On-Line Command P -- Select Pulse Dialing Method Q -- Result Code Display Options Sr= -- Write to an S-Register Sr? -- Read an S-Register T -- Select Tone Dialing Method V -- Result Code Format Options W -- Negotiation Progress Message Selection X -- Call Progress Options Y -- Long Space Disconnect Options Z -- Soft Reset Command &B -- V.32 Auto Retrain Options &C -- Data Carrier Detect Options &D -- Data Terminal Ready Options &F -- Recall Factory Profile &G -- Guard Tone Selection &J -- Jack Type Selection (Auxiliary Relay Options) &K -- Local Flow Control Options &L -- Line Type Selection (Dialup/Leased) &O -- PAD Channel Selection &Q -- Communications Mode Options &R -- RTS/CTS Options &S -- Data Set Ready Options &T -- Test Options &U -- Trellis Coding Options &V -- View Configuration Profiles &W -- Write Active Profile to Memory &X -- Synchronous Transmit Clock Source &Y -- Select Stored Profile For Hard Reset &Zn=x -- Store Telephone Number 1.2 Result Code Listing 1.2.1 Command Response and Call Progress Monitoring 0 -- OK 1 -- CONNECT 2 -- RING 3 -- NO CARRIER 4 -- ERROR 5 -- CONNECT 1200 6 -- NO DIALTONE 7 -- BUSY 8 -- NO ANSWER 10 -- CONNECT 2400 11 -- CONNECT 4800 12 -- CONNECT 9600 14 -- CONNECT 19200 22 -- CONNECT 1200/75 23 -- CONNECT 75/1200 28 -- CONNECT 38400 1.2.2 Negotiation Progress Messages 40 -- CARRIER 300 44 -- CARRIER 1200/75 45 -- CARRIER 75/1200 46 -- CARRIER 1200 47 -- CARRIER 2400 48 -- CARRIER 4800 50 -- CARRIER 9600 66 -- COMPRESSION: CLASS 5 67 -- COMPRESSION: V.42BIS 68 -- COMPRESSION: ADC 69 -- COMPRESSION: NONE 70 -- PROTOCOL: NONE 71 -- PROTOCOL: ERROR-CONTROL/LAP-B 72 -- PROTOCOL: ERROR-CONTROL/ LAP-B/HDX 73 -- PROTOCOL: ERROR-CONTROL/LAP-B/AFT 74 -- PROTOCOL: X.25/LAP-B 75 -- PROTOCOL: X.25/LAP-B/HDX 76 -- PROTOCOL: X.25/LAP-B/AFT 77 -- PROTOCOL: LAP-M 78 -- PROTOCOL: LAP-M/HDX V.42 79 -- PROTOCOL: LAP-M/AFT 80 -- PROTOCOL: ALT 91 -- AUTOSTREAM: LEVEL 1 92 -- AUTOSTREAM: LEVEL 2 93 -- AUTOSTREAM: LEVEL 3 1.2.3 Information Text (INFO-TEXT) 1.3 S-Register Listing S0 -- Ring to Answer After S1 -- Ring Count S2 -- Escape Sequence Character S3 -- Carriage Return Character S4 -- Line Feed Character S5 -- Backspace Character S6 -- Wait Before Blind Dialing S7 -- Wait for Carrier after Dialing S8 -- Duration of Delay for Comma Dial Modifier S9 -- Carrier Detect Response Time S10 -- Delay Between Lost Carrier and Hang Up S11 -- Multi-Frequency Tone Duration S12 -- Escape Sequence Guard Time S18 -- Modem Test Timer S25 -- DTR Detection S26 -- RTS to CTS Interval S30 -- Inactivity Time-out S33 -- AFT Options S36 -- Negotiation Failure Treatment S37 -- Desired DCE Line Speed S38 -- Delay Before Forced Hang up S44 -- Asynchronous Framing Technique Selection S46 -- Error-Control Protocol Selection S48 -- Enabling/Disabling Feature Negotiation S49 -- ASB buffer size lower limit S50 -- ASB buffer size upper limit S53 -- Global PAD Configuration S63 -- Leased line carrier level S69 -- Link Layer Window Size S70 -- Maximum Number of Retransmissions S71 -- Link Layer Time-out S72 -- Loss of Flag Idle Time-out S73 -- No Activity Time-out S74, S75 -- Minimum Incoming Logical Channel Number (LCN) S76, S77 -- Maximum Incoming Logical Channel Number (LCN) S78, S79 -- Outgoing Logical Channel Number (LCN) S80 -- Packet Layer N20 Parameter S81 -- Packet Layer T20 Parameter S82 -- Break Signaling Technique S84 -- Adaptive start up negotiation (ASU) S85 -- ASU Negotiation Report S86 -- Connection Failure Cause S92 -- MI/MIC Options S93 -- V.25bis DTE interface speed S94 -- Command Mode Selector S95 -- Negotiation Message Options S97 - V.32 Automdode V.22/V.22bis Probe Timing 1.4 Additional Command Set Definitions AT -- Command Prefix +++ -- Escape Sequence -- End-of-line Character A/ -- Repeat Last Command Chapter Two: V-series(TM) X.25 Communications 2.1 Modem Configuration for X.25 Communications 2.1.1 Controlling Automatic Feature Negotiation 2.1.2 PAD Channel Selection 2.2 PAD Configuration 2.2.1 PAD Commands ACC -- Accept Call Command CALL -- Call Command (and Call Facilities) CHAN -- Channel Selection Command CLR -- Clear Channel Command EXEC -- Execute String Command EXIT -- Exit PAD Command INT -- Interrupt Command PAR? -- Read Parameter Command PROF -- PAD Profile Command RESET -- PAD Reset Command RPAR? -- Read Remote PAD Parameter Command RSET -- Set Remote PAD Parameter Command STAT -- Status of Current Channel Command SET -- Set PAD Parameter Command 2.2.2 PAD Parameters Parameter 1 -- PAD Recall Using a Character Parameter 2 -- Echo Parameter 3 -- Selection of Data Forwarding Signal Parameter 4 -- Selection of Idle Timer Delay Parameter 5 -- Ancillary Device Control Parameter 6 -- Control of PAD Result Codes Parameter 7 -- Action on Receipt of Break from Terminal Parameter 8 -- Discard Output Parameter 9 -- Padding after Carriage Return Parameter 10 -- Line Folding Parameter 11 -- Terminal Speed Parameter 12 -- Flow Control of the PAD by Local Terminal Parameter 13 -- Line Feed Insertion after Carriage Return Parameter 14 -- Line Feed Padding Parameter 15 -- Editing Parameter 16 -- Character Delete Parameter 17 -- Line Delete Parameter 18 -- Line Display Parameter 19 -- Editing PAD result codes Parameter 20 -- Echo Mask Parameter 21 -- Parity Treatment Parameter 22 -- Page Wait National Parameter 70 -- Streaming Data Forwarding National Parameter 71 -- Character Format National Parameter 72 -- Break Signal Timing National Parameter 73 -- Break Signal Duration National Parameter 74 -- Disable PAD Parameter by the Remote PAD National Parameter 100 -- Default Maximum Packet Size National Parameter 101 -- Default Maximum Window Size National Parameter 103 -- Reset Request Response Timer National Parameter 104 -- Clear Request Response Timer National Parameter 105 -- Interrupt Response Time National Parameter 106 -- Reset Request Retransmission Counter National Parameter 107 -- Clear Request Retransmission Counter National Parameter 108 -- Channel Allocation Parameter 2.3 PAD Profiles Factory-Set Profile CCITT Simple Standard Profile CCITT Transparent Standard Profile Error-Control/LAP-B Profile 2.4 Typical X.25 Scenarios Appendix A: Communication Options A.1 Transmission and DTE Types A.1.1 Asynchronous Transmissions A.1.2 Synchronous Transmissions A.2 Communication Modes -- &Q A.2.1 Asynchronous Mode -- &Q0 A.2.2 Synchronous Mode 1: sync/async -- &Q1 A.2.3 Synchronous Mode 2: stored number dial -- &Q2 A.2.4 Synchronous Mode 3: manual dial with data/talk switch -- &Q3 A.2.5 Synchronous Mode 4: Hayes AutoSync -- &Q4 A.2.6 Error-Control Mode -- &Q5 A.2.7 Asynchronous Mode with Automatic Speed Buffering (ASB) -- &Q6 Appendix B: Troubleshooting Tips B.1 The Communication Link B.2 Troubleshooting the Process B.2.1 Problems in Getting Started B.2.2 Problems Encountered During Communications B.3 Special Environment Considerations B.3.1 Custom Modem Setup for Mainframe or Minicomputer Host B.3.2 Custom Modem Setup for Telephone System Requirements B.4 Using AT Commands to Test Modem Circuits B.4.1 Available Tests B.4.2 Performing a Test B.4.3 Testing with Analog Loopback B.4.4 Testing with Digital Loopback B.4.5 Testing the Tone Dialer -- &T2 B.5 Testing the Cable B.5.1 Cable Quality B.5.2 Checking Cable Signals -- &T19 B.6 Testing Internal Memory Appendix C: Modem-to-DTE Interface C.1 EIA 232-D/CCITT V.24 Interfaces C.2 Signals Used in the EIA 232-D Interface C.3 EIA 232-D Signal Definitions C.4 Modem Interface Connector Appendix D: Modem Application Development D.1 Modem Identification D.2 Result Code Recognition D.3 Modem Preparation D.3.1 Reset D.3.2 Setup D.4 Connect Processing D.4.1 Originating a Call D.4.2 Answering a Call D.4.3 Using the CD Line D.4.4 Aborting a Connect Request D.5 Carrier Loss Detection D.5.1 Using the CD Line D.5.2 Scanning the Incoming Data Stream D.6 Escape and Hang Up D.6.1 Escaping the Modem to Command State D.6.2 Using DTR to Escape or Hang Up D.7 Modem Re-configuration D.8 Timing Considerations D.8.1 Programming for Time D.8.2 When to Consider Time D.8.3 Recovering When "Out of Sync" D.9 General Tips and Techniques Index ============================================================================= Introduction This Technical Reference for Hayes Modem Users offers additional information about the Hayes Standard AT Command Set for users who want to use the command set to control the modem, rather than using full-featured software. To help you do this, the complete command set is defined in greater detail than that provided on the AT Command Set Reference Card that accompanied your modem. All of the commands in the set are included in this document. You'll also find additional discussions on some of the more complicated options, such as synchronous communications, and the interactions between communication standards, negotiation commands, and modem speeds. In addition, information about the connections between the modem and the DTE (computer or terminal) is included. With the information provided here, you should be able to configure your modem with AT commands for a variety of communication environments. If you are just starting out with communications programming, this reference should provide you with sufficient tips to address the modem's features through a software program of your own. If this reference seems more technically oriented than you anticipated, we suggest that you purchase one of Hayes Smartcom Products. Any of these fine programs will fully control the modem for almost any telecommunication requirements. ***************************************************************************** Who Should Use this Reference Users of full-featured communications software such as Hayes Smartcom Products will not need this reference. This reference is provided for... * users of communications software packages which require the user to enter modem configuration strings. * users who will be installing and operating Hayes modems in a non-PC environment. * users who control their modems directly with terminal emulation software. * technical personnel responsible for custom installations and applications. Additional information is available for communications software developers. If you are, or would like to become, a registered Hayes Software Developer, you may receive additional technical material on Hayes products. For information on qualification and registration procedures, contact your nearest Hayes Customer Service facility. (Refer to the Customer Service Information folder provided with your modem for location and telephone number.) ***************************************************************************** How this Reference is Organized This reference is divided into two chapters and four appendices: Chapter One: The Hayes Standard AT Command Set... includes definitions of the Hayes AT Command Set including the commands, result codes, and S-registers. Chapter Two: V-series(TM) X.25 Communications... includes definitions of the commands used for X.25 packet switched communications, PAD and National Parameters, and listings for four PAD profiles. Appendix A: Communication Options... describes the various asynchronous and synchronous transmission modes supported by Hayes modems and includes a discussion of the AT commands related to these modes. Appendix B: Troubleshooting Tips... provides special environmental considerations and offers suggestions for remedying problems in modem communications. Appendix C: Modem-to-DTE Interface... discusses the requirements and capabilities of the modem's data terminal equipment (DTE) interface. Appendix D: Modem Application Development... offers suggestions for developing applications software using the AT command set. ***************************************************************************** How to Use this Reference The commands and procedures described in this reference are intended for use with a program that provides a command line interface to the modem. or if the modem is connected to an asynchronous terminal to which commands can be entered and sent through the serial port to the modem. Although commands are not required when using Hayes Smartcom(TM) products, Smartcom EZ(TM), Smartcom II(TM), and Smartcom III(TM) all support a command line interface to the modem. Refer to the Smartmodem Product User's Reference or V-series System Product User's Reference (depending on the modem you purchased) for descriptions of the features that are enabled by the AT Commands and S- Registers defined here. These user's references both explain how to issue AT Commands, and read and set S-Registers/PAD Parameters. Please note that this reference is not a list of the features supported by your modem, but a general guide to the Hayes AT Command Set as used to control Hayes modems. For a list of features supported by your modem, refer to the documentation included with your modem. This Modem Technical Reference is a supplement to the documentation provided with your modem, not a replacement. ============================================================================= Chapter One: The Hayes Standard AT Command Set This chapter is divided into three sections: AT commands, Result Codes, and S- Registers. The first section defines individual AT commands. Commands are listed in alphabetically for easy reference. The second section defines the Result Codes that can be returned by Hayes modems. These are listed in numeric order. The third section defines Hayes Smartmodem Registers. These, too, are in numeric order. For completeness, definitions of the AT command prefix, the end-of-line character, and other information related to the Hayes Standard AT Command Set are also included. For the factory setting and available options/ranges for commands and registers, use the AT Command Set Reference Card provided with your modem. Unless a command, register, or result code is listed on this card, it is not supported by your modem, although it appears in this document. ***************************************************************************** 1.1 AT Command Listing Each step in the evolution of Hayes modems has added to the feature set that has enhanced the definition of the Hayes standard. The diagram below shows the major steps in the process. A -- Answer Command The A command instructs the modem to go off hook and respond to an incoming call, then handshake with the remote modem. When the modem returns the RING result code, issue ATA. The modem will send an answer carrier signal to the originating modem and wait for an originate carrier signal. When the modem receives the carrier from the originating modem, the modems go through a handshaking process then go on-line. The modems return the CONNECT XXXXX result code. If no carrier signal is received within the time specified in Register S7, the modem hangs up, returns the NO CARRIER result code, and enters the command state. B -- Select Communication Standard The B command is used to specify the desired communications standard setting at a particular modem line speed. Because options can select between groups of options, more than one combination of communication standard and speed can be selected. For example, you can issue B1 and B16; both will be in effect because they do not reference the same line speed. However, choosing B1 then B5 selects B5, and replaces B1 as the standard for 1200 bps communications. The most recent selection chosen from any given group will be in effect for that parameter group. GROUP 1 Values Description ----------------------------------------------------------------------------- 0 or none V.22 when modem is at 1200 bps 1 U. S. Domestic 212A when modem is at 1200 bps 2 V.23 R1200/T75 bps ASB when modem is at T1200/R1200 bps 3 V.23 T1200/R75 bps ASB when modem is at T1200/R1200 bps 4 V.23 T1200/R75 bps split speed when modem is at T1200/R75 bps 5 V.23 1200 bps half duplex when modem is at T1200/R1200 bps GROUP 2 Values Description ----------------------------------------------------------------------------- 10 V.23 R1200/T75 bps split speed when modem is at R1200/T75 bps 11 U. S. Domestic 212A when modem is at 1200 bps GROUP 3 ----------------------------------------------------------------------------- Values Description 15 V.21 when modem is 110/300 bps 16 U. S. Domestic 103 when modem is at 110/300 bps GROUP 4 ----------------------------------------------------------------------------- Values Description 20 V.23 R600/T75 bps ASB when modem is T600/R600 bps 21 V.23 T600/R75 bps ASB when modem is T600/R600 bps 22 V.23 T600/R75 bps split speed when modem is T600/R75 bps 23 V.23 600, half duplex when modem is 600 bps GROUP 5 ----------------------------------------------------------------------------- Values Description 30 V.22bis when modem is 2400 bps 31 V.27ter when modem is 2400 bps GROUP 6 ----------------------------------------------------------------------------- Values Description 40 V.27ter when modem is 4800 bps 41 V.32 full duplex when modem is 4800 bps 42 V.32 half duplex when modem is 4800 bps 44 V.23 half duplex when modem is 4800 bps GROUP 7 ----------------------------------------------------------------------------- Values Description 50 V.29 HDX when modem is 7200 bps GROUP 8 ----------------------------------------------------------------------------- Values Description 60 V.32 full duplex when modem is 9600 bps 61 V.32 half duplex when modem is 9600 bps 63 V.29 half duplex when modem is 9600 bps C -- Carrier Control Selection The C command is used by some Hayes modems, such as Smartmodem 1200, to control the transmit carrier. In these instances, C0 instructs the modem not to send carrier (i.e., puts modem in a receive-only mode). High-speed modems (those capable of speeds greater than 1200 bps) accept C1 without error in order to assure backward compatibility with communications software that issues C1. However, these modems do not support C0. C0 - Transmit carrier always off (not supported in high-speed modems) C1 - Normal transmit carrier switching D -- Dial Command The D command places the modem in originate mode; it then functions as an auto-dialer. Whether the command is issued on a line by itself, or followed immediately by the telephone number, it must be preceded by the AT prefix and terminated with a The dial string is a combination of dial digits and dial modifiers. If the modem is off hook, it will neither initially wait nor attempt to detect dial tone before proceeding. The D command is not valid when the modem is on-line or if either &Q2 or &Q3 is in effect. Parentheses and hyphens in a dial string are ignored by the auto-dialer, but are counted as characters in the 255-character command buffer. Result Codes Description ----------------------------------------------------------------------------- BUSY If X3 or X4 are selected or W dial modifier is used and busy is detected NO DIALTONE If X2 or X4 are selected and 1 second of dial tone is not detected within 5 seconds If W dial modifier is processes and then 3 seconds of dial tone is not detected within the time specified by S7 ERROR If the S=n dial modifier is processed and the n value is out of range (refer to the S dial modifier in this section) or if the total number of characters in the command line plus the stored dial string exceeds 255 characters NO ANSWER If @ dial modifier is used and then no signal is detected for at least five continuous seconds before the time specified by S7 OK If aborted by DTR ON-to-OFF whenever certain combinations of &D and &Q are in effect. Refer to the &D command in this chapter for details. If the ; dial modifier is processed in the dial string. If aborted by a character from the DTE during the dialing process Dial Modifiers Dial modifiers can be combined with the dial (D) command to perform a series of operations within a single command line. For example, ATDT9W1552368!@#71234; instructs the modem to use tone dialing to access a number outside a PBX, wait for dial tone, dial the number 1552368, enter a timed break recall, wait for quiet answer, and issue the PBX transfer code #7 before dialing extension number 1234, then return to the command state before initiating the handshake. 0-9 A B C D # * -- Digits/Characters for Dialing The digits/characters 0-9 A B C D # * are used to specify what numbers the modem will dial. The characters A B C D # * represent specific tone pairs and therefore can be used only when tone dialing is selected; these symbols are ignored when pulse dialing is used. P -- Pulse Dialing Method The P dial modifier selects the pulse method of dialing. The P modifier can be issued with the dial command, or alone, to indicate the method used for subsequent dialings. The factory-set method is pulse. Once this method is selected, it is used until the other is chosen, or the modem is reset. T -- Tone Dialing Method The T dial modifier selects the tone method of dialing. The T modifier can be issued with the dial command, or alone, to indicate the method used for subsequent dialings. Once this method is selected, it is used until the other is chosen, or the modem is reset. W -- Wait for Second Dial Tone The W dial modifier instructs the modem to wait for dial tone before proceeding. If dial tone detection is not completed within the preset time limit, the modem hangs up and returns the NO DIALTONE result code. Some PBXs do not return a secondary proceed indication (second dial tone). The W dial modifier is not effective in such systems and should not be used. , -- Delay Processing of Next Character The comma (,) dial modifier in a dial string causes the modem to pause before processing the next character or symbol in the command line. The duration of the pause is determined by the value held in Register S8. The comma is frequently inserted after the 9 (digit generally used to gain outside access from a PBX) to allow sufficient time for the dial tone to occur before the modem dials the telephone number. @ -- Wait for Quiet Answer The @ dial modifier instructs the modem to listen for five seconds silence before continuing. The number of seconds the modem waits for silence is determined by the value held in S7. This modifier is useful when dialing telephone systems that produce no dial tone. If a five-second silence has not been detected within the period set in S7, the modem hangs up and returns the NO ANSWER result code. If it detects the five seconds of silence, the modem processes the remaining characters in the dial string. Note that the modem does not listen for silence until it first detects dial tone and some other signal, such as a ringing signal, that lasts longer than 210 milliseconds. For example, to dial 1552368, wait for a quiet answer, then dial a security code 85939, wait for a second dial tone, and dial extension 423 you would issue the following command: ATDT 1552368 @ 85939 W 423 . ! -- Timed Break Recall (Hookflash) The ! dial modifier issues a timed break recall signal, which causes the modem to hang up for 75 milliseconds, then reconnect. This feature can be used to access such PBX features as call transfer. ; -- Return to Command State after Dialing The semicolon (;) dial modifier, used only at the end of a command line (just before the ), instructs the modem to return to the command state immediately after dialing, without breaking the connection. The ; is useful when calling an electronic service, such as that offered by a bank, that permits you to use tones to transmit numbers once a connection has been established. The modem can send tones even if your telephone cannot. The example below illustrates the use of the semicolon modifier in communications with an electronic banking service. ATDP 1552368; Dials bank using pulse method OK Command executed, but keeps the modem in command state (no carrier handshake takes place) ATDT 4768; Sends an ID code via tones and maintains modem in command state. OK Modem in command state; command executed. In this example, the ; differs from the +++ in that the escape sequence places the modem in the command state only when two modems have completed a handshake. The semicolon keeps the modem in command state; no CONNECT XXXXX result code is displayed. DS=n -- Dialing a Stored Telephone Number A stored number can be dialed from an asynchronous terminal by following the dial (D) command with the S modifier, an equal sign, and the location of the stored number (see &Zn=x command at the end of this section). The format of the modifier is S=n, where n is location 0-3. If ATDS=2 were issued, for example, the modem would dial the string stored in memory location three of its "telephone book." R -- Originate a Call in Answer Mode The dial modifier R (Reverse mode) enables the modem to dial an originate- only modem by placing a call in answer mode. This modifier must be entered at the end of the dialling (D) command string, before the . The R modifier directs the modem to act as if it had been sent an A command in that part of the command string. E -- Command State Character Echo Selection The E command determines whether characters are echoed to the DTE from the modem when it is command state. Some computers and terminals do not send the characters you type to the screen; they only transmit them to the remote system through the serial port. In this case, if Command State character echo were not enabled by the modem, you would be unable to see what you type. If the DTE does echo the characters you type in command state, and this function is enabled in the modem, each character typed will appear twice. E0 Command state character echo disabled E1 Command state character echo enabled F -- On-line State Character Echo Selection The F command is used by some Hayes modems, such as Smartmodem 1200, to determine whether characters are echoed to the DTE from the modem when it is in the on-line state. High-speed Hayes modems do not support the F0 option. However, because the F command may be issued by older communications software, F! is supported to assure backwards compatibility. F0 On-line character echo enabled (where not supported, ERROR result code is returned) F1 On-line character echo disabled H -- Hook Command Options The H command provides control over the line relay. Its most common use is with the H0 option to initiate the Hangup Process and place the modem on hook.H1 takes the modem off hook. H0 Execute the Hangup process if in the "on-line" command state or the local analog loopback and analog loopback selftest conditions H1 Go off hook; do not execute the Handshake Process I -- Internal Memory Tests The various forms of the I command instruct the modem to query its memory for information about itself. the results of these tests are frequently used by programmers for the purpose of determining compatibility with software. Because these commands request information about the modem's firmware, they are not run when a connection has been established with a remote modem. I0 -- display product code This option reports the product code of the modem to the DTE. The modem produces information text dependent upon its highest DCE line speed. The responses below are examples: Result Codes..Description ----------------------------------------------------------------------------- 300 Smartmodem 300(TM) 120 Smartmodem 1200(TM), Smartmodem 1200B(TM), Smartmodem 1200C(TM), Smartmodem 1200A(TM) 240 Smartmodem 2400(TM), Smartmodem 2400B(TM), Smartmodem 2400P(TM), Smartmodem 2400Q(TM), Smartmodem 2400M(TM), V-series Smartmodem 2400, V-series Smartmodem 2400B, V-series Smartmodem 2400P, V-series Smartmodem 2400M 960 Smartmodem 9600, V-series Smartmodem 9600(TM), V-series Smartmodem 9600B(TM), V-series Smartmodem 9600P(TM), V-Series ULTRA Smartmodem 9600 I1 -- display ROM checksum The I1 command instructs the modem calculate the value of the ROM checksum. The response is a 3-digit decimal information text, the sum of all of the bytes in ROM. I2 -- perform ROM checksum test This command instructs the modem to verify the ROM checksums. Depending on whether the ROM checksum has been found to be correct, the modem produces an info text that resembles a verbose result code. The modem memory test compares the ROM checksum and tests it against the correct sum, also stored in ROM. Rather than returning a value in the way the I1 one command does, the I2 command generates a result code. When the checksum is valid, the response is: OK. When the ROM checksum fails, the modem responds with ERROR. I4 -- identify product features The capabilities and features of the modem are encoded into a string of info- text that consists of several strings that are ASCII character representations of hex numerals which are bit-mapped. The first character of each string identifies which bit maps are in that string. For example, the "a-string" starts with a lower case "a" and identifies most of the basic modem capabilities such as modulation standards supported and support for AutoSync. Since the following tables identify features for Hayes modem products, the values included here are subject to change and expansion. The I4 info-text displayed: a097800C204C264 bF60410000 r1031111111010000 r3000111010000000 surrounded by additional and characters as are required by the V command option in effect. According to convention, all and characters are defined by S3 and S4, respectively. The meanings of the a, b, r1, and r3 strings currently defined are described below. I4 "a" String.. The first string, the a-string, is encoded by characters, hex symbols following the "a" character, each of which represents four bits. a D1 D2 D3 D4 D5 D6 D7 D8 D9 D10 D11 D12 D13 D14 D15 D16 D17 D18 D1, D2 Reserved D3 Bit 3: Indicates modem based on SM1200FE commands Bit 2: Indicates modem based on SM2400 commands Bit 1: Indicates that modem supports &J commands Bit 0: Indicates that modem supports &L commands D4 Bit 3: Indicates that modem supports AutoSync (&Q4) D5 Bit 3: Plug-in board modem product Bit 2: Stand alone modem product Bit 1: Supports &H0 through &H4 Bit 0: Supports &I0 through &I4 D7 Bit 3: Supports V.22 at 1200 bps Bit 2: Supports Bell 212A Bit 1: Supports ASB (&Q6) in V.23 75xmt/1200rcv Bit 0: Supports ASB (&Q6) in V.23 1200xmt/75rcv D8 Bit 3: Supports V.23 1200xmt/75rcv Bit 2: Supports V.23 1200 half duplex Bit 1: Supports V.23 75xmt/1200rcv Bit 0: Supports V.23 75xmt/600rcv D9 Bit 3: Supports V.21 100/300 Bit 2: Supports ASB (&Q6) in V.23 75xmt/600rcv Bit 1: Supports ASB (&Q6) in V.23 600xmt/75rcv Bit 0: Supports V.23 600xmt/75rcv D10 Bit 2: Supports V.22bis at 2400 bps Bit 1: Supports V.27ter at 2400 bps Bit 0: Supports V.27ter at 4800 bps D11 Bit 3: Supports V.32 full duplex at 4800 bps Bit 2: Supports V.32 half duplex at 4800 bps Bit 1: Supports (Reserved) at 4800 bps Bit 0: Supports V.29 half duplex at 4800 bps D12 Bit 3: Supports V.29 half duplex at 7200 bps Bit 2: Supports V.32 full duplex at 9600 bps Bit 1: Supports V.32 half duplex at 9600 bps Bit 0: Supports (Reserved) at 9600 bps D13 Bit 3: Supports V.29 half duplex at 9600 bps Bit 2: Supports Bell 103 110/300 bps D15 Bit 1: Supports S95 Bit 5 for COMPRESSION: result code Bit 0: Supports S95 Bit 4 for AUTOSTREAM: result code D16 Bit 3: Supports S95 Bit 3 PROTOCOL: result code Bit 2: Supports S95 Bit 2 CARRIER result code Bit 1: Supports S95 Bit 1 CONNECT/ARQ result code Bit 0: Supports S95 Bit 0 CONNECT XXXX (for DCE rate) I4 "b" String The second string, the b-string, is composed of the ASCII character "b" followed by nine bytes (D1-D9). The bit map for each byte is defined as follows: b D1 D2 D3 D4 D5 D6 D7 D8 D9 D1 Bit 3: V.42 Alternate Protocol Supported Bit 2: V.42 LAPM Protocol Supported Bit 1: X.25 Protocol Supported Bit 0: LAPB (Original V-series Point-to-Point error-control) Protocol Supported D2 Bit 3: Reserved (should be set to zero) Bit 2: MNP Class 5 Supported Bit 1: V.42bis Supported Bit 0: Compression Through the X.25 Network Supported D3/D4 These combine to indicate the number of AutoStream Type A channels which are supported. The formula (D3*16 + D4) is used. Zero means AutoStream is not supported I4 "r1" and "r3" strings These ID strings allow software to determine the available speeds that may be used to send AT commands. The r1-string contains a bit map that indicates at which DTE rates the autobaud process is supported. The r3-string is issued if synchronous DTE speeds are supported. The map indicates which DTE rates are supported in Synchronous modes. Each r-string begins with the lower case letter "r" and may be followed by as many as 39 additional characters, not counting 's that will be used to separate them from other strings. Those 39 additional characters are limited to the ASCII-HEX alphabet 0-9 and A-F. After the two lead-in characters (i.e., r), all subsequent characters contain the DTE rate maps. All maps have the same mapping for convenience to software. (Refer to the chart below.) Not all bit assignments are possible: for example, the split speeds have no meaning in the r3 synchronous map and are always filled with zeros. In r1, if the bit is filled with a 1, the corresponding DTE rate is supported for sending AT commands to the device. A zero indicates that DTE rate is not supported for AT commands. In the r3 map, the bits simply indicate which DTE rates are supported for synchronous operation on-line. This does not indicate, however, the supported rates for synchronous V.25bis commands. Split speeds if available are marked in the r1 string only when the appropriate B command option has been selected. Future expansion of these strings may include new speeds that are not in strict ascending order. DTE Rate Bit Map for r1 and r3 Strings Character Bit # DTE Rate ----------------------------------------------------------------------------- 3:1 bit 0 45.45 bps 3:2 bit 1 50 3:4 bit 2 75 3:8 bit 3 75/600 (xmt is 75, rcv is 600) 4:1 bit 4 75/1200 4:2 bit 5 110 4:4 bit 6 134.5 4:8 bit 7 50 5:1 bit 8 300 5:2 bit 9 450 5:4 bit 10 600 5:8 bit 11 600/75 6:1 bit 12 1200 6:2 bit 13 1200/75 6:4 bit 14 1800 6:8 bit 15 2000 7:1 bit 16 2400 7:2 bit 17 3000 7:4 bit 18 3600 7:8 bit 19 4200 8:1 bit 20 4800 8:2 bit 21 5400 8:4 bit 22 6000 8:8 bit 23 6600 9:1 bit 24 7200 9:2 bit 25 7800 9:4 bit 26 8400 9:8 bit 27 9000 10:1 bit 28 9600 10:2 bit 29 12000 10:4 bit 30 14400 10:8 bit 31 16800 11:1 bit 32 19200 11:2 bit 33 21600 11:4 bit 34 24000 11:8 bit 35 26400 12:1 bit 36 28800 12:2 bit 37 31200 12:4 bit 38 33600 12:8 bit 39 36000 13:1 bit 40 38400 13:2 bit 41 43200 13:4 bit 42 48000 13:8 bit 43 52800 14:1 bit 44 56000 14:2 bit 45 57600 14:4 bit 46 62400 14:8 bit 47 64000 15:1 bit 48 67200 15:2 bit 49 72000 15:4 bit 50 76800 15:8 bit 51 81600 16:1 bit 52 86400 16:2 bit 53 91200 16:4 bit 54 96000 16:8 bit 55 100800 17:1 bit 56 105600 17:2 bit 57 110400 17:4 bit 58 115200 17:8 bit 59 reserved ("0") L -- Speaker Volume Level Selection The L command setting determines the volume level of the speaker, when supported by the modem. Some modems use the speaker of the computer in which they are installed. In this case, where supported, the L command adjusts the speaker volume as indicated in the options below for the duration of the communications session. L0 Low speaker volume L1 Low speaker volume L2 Medium speaker volume L3 High speaker volume M -- Speaker On/Off Selection The M command setting determines whether the speaker function of the modem is on or off. Some modems use the speaker of the computer in which they are installed. In this case, where supported, the M command turns the speaker on an off as indicated in the options below for the duration of the communications session. M0 Speaker always off. M1 Speaker on until carrier detected. M2 Speaker always on; stays on after carrier is detected. M3 Speaker off as digits are dialed, but on during ringback and on until carrier signal is detected. N -- Negotiation of Handshake Options The N command selects whether or not the local modem performs a negotiated handshake with a remote modem when the communications speeds of the two modems are different. The options for this command are useful when a particular speed and communication standard are required. Both symmetrical and asymmetrical protocols can be selected. Note that the options supported by for this command vary significantly between country-specific implementations. N0 When originating or answering, handshake only at the communication standard specified by S37 and B command N1 When originating, begin handshake at the communication standard specified by the B command and S37. During handshake fallback to a lower speed may occur When answering, negotiate according to the following sequence of communication standards: V.32, Ping Pong, V.22bis, V.22, and V.21 N2 When originating, begin handshake at the communication standard specified by the B command and S37. During handshake fallback to a lower speed may occur When answering, negotiate according to the following sequence of communication standards: V.32, Ping Pong, V.22bis, V.22, V.23, and V.21 N3 When originating, handshake only at the communication standard specified by S37 and B command. When answering, negotiate according to the following sequence of communication standards: V.32, Ping Pong, V.22bis, V.22, and V.21 N4 When originating, handshake only at the communication standard specified by S37 and B command. When answering, negotiate according to the following sequence of communication standards: V.32, Ping Pong, V.22bis, V.22, V.23, and V.21 N5 When originating, begin handshake at the communication standard specified by B command and S37. During handshake fallback to a lower speed may occur When answering, handshake only at the communication standard specified by S37 and B. O -- On-Line Command If the modem is in the on-line command state, then the O0 command causes it to go to the on-line state of the previously established connection. If the O1 command is issued (modems supporting 2400 bps and higher), the modem goes to on-line state and retrains its adaptive equalizer. If the modem is off hook in the idle state, then O0 and O1 (modems supporting 2400 bps and higher) cause it to go to the handshaking state. Originate or answer mode is determined from the last D or A command or R dial modifier that was selected. If the modem is on-hook, idle, or if the modem is in a test condition, a command execution error results. Note that O1 serves a different purpose in lower speed modems (e.g., Smartmodem 1200 and Smartmodem 300). P -- Select Pulse Dialing Method The P command instructs the modem to use pulse dialing. Dialed digits will be pulse dialed until a T command or dial modifier is received. This command is also discussed under Dial modifiers, in conjunction with the D command. Q -- Result Code Display Options The Q command controls whether the result codes generated by the modem are displayed to the attached DTE. Some software does not function properly when modem responses are returned. Q0 Result codes enabled Q1 Result codes disabled Q2 Disables the RING result code. In answer mode, also disables CONNECT and NO CARRIER result codes Sr -- Addresses an S-Register The Sr command points to a specific S-Register. Subsequent commands, such as ? and =, may read or write to the selected register. Note that S0 is the factory-set pointer for this command, and that the S-address is not stored in a stored profile. Thus, the &F, Z0, and Z1 commands will select S0 and possibly affect subsequent ? and = commands unless they are preceded by an Sr command. Note that the value of S0 is of course storable; it is the pointer to S0 that is not storable. Sr=n -- Write To An S-Register The Sr=n command is writes a value to a specified register. The value of n is written to the S-Register specified by r, overriding the previous value. If no n suffix is present, the address previously selected via Sr is used. If no n suffix is present, the value 0 is written. Sr? -- Read An S-Register The contents of S-Register r are sent to the DTE as three decimal digits. This informational text response is formatted with as determined by the V command currently in effect. If no n (suffix) is present, the last register selection is assumed. (Refer to the Sr command.) On power up, the factory-set selection is 0. Note: ? is interpreted by the modem as Sr?. T -- Select Tone Dialing Method The T command instructs the modem to send DTMF tones while dialing. Dialed digits will be tone dialed until a P command or dial modifier is received. This command is also discussed under Dial modifiers, in conjunction with the D command. V -- Result Code Format Options The V command determines whether result codes (including call progress and negotiation progress messages) are displayed as numbers or words. V0 Result codes displayed in numeric form V1 Result codes displayed in verbose form W -- Negotiation Progress Message Selection The W command works in conjunction with S95 (where supported) to determine which result codes will be used to describe the type of connection and protocol, etc., that resulted from handshaking and negotiation. The W command supports extended result codes in addition to the CONNECT result code. When the modem is operated in error-control mode (&Q5 is in effect), W command and S95 together allow the user to select these additional result codes: CARRIER PROTOCOL AUTOSTREAM COMPRESSION CONNECT Any result codes enabled by the W command and S95 will be generated in the order indicated above. If AutoStream is not being used, no AutoStream result code is returned. Result codes not enabled by the W command option in effect may be turned-on by setting certain bits in S95. The W command options below are available when S95 is configured for any setting other than the factory- setting of 0. W0 CONNECT result code reports DTE speed, and if S95=0, then disable all extended result codes W1 CONNECT result code reports DTE speed, and if S95=0, then enable the CARRIER and PROTOCOL extended result codes W2 CONNECT result code reports DCE speed, and if S95=0, then disable all extended result codes Refer to the S95 bit map description in the next section. Note that selecting W0 and setting S95=12 is the same as selecting W1; and that selecting W0 and setting S95=1 is the same as selecting W2. S95 cannot be configured to force W2 to report DTE speed in the CONNECT result code; and that there is no setting of S95 that will force W1 not to produce the CARRIER and PROTOCOL result codes. S95 extends the functionality of the W command. The W command with S95=0 (factory setting) maintains backwards compatibility with previous V-Series System Products. However, selecting W0 and setting S95 as required allows you to tailor result codes characteristics to your own requirements. X -- Call Progress Options The X command enables tone detection options used in the dialing process. As these functions are enabled and disabled, the modem's result code reporting is also affected. For this reason, this command is frequently used to control the modem's range of responses; however, its primary function is that of controlling the modem's call response capabilities. Result code definitions are covered in the next section. X0 Busy and dial tone detection are disabled. Only result codes 0-4 are enabled. Only the CONNECT result code is permitted, and no indication of the telephone line speed. This setting overrides any other result code selections made with the W command and S95 X1 Busy and dial tone detection are disabled. Result codes 0-5 are enabled and linespeed reporting with CONNECT XXXX messages. W command options and S95 are enabled X2 Busy detection is disabled. Dial tone detection is enabled. Result codes 0-6 are enabled and linespeed reporting with CONNECT XXXX messages. W command options and S95 are enabled X3 Busy detection is enabled. Dial tone detection is disabled. Result codes 0-5 and 7 are enabled and linespeed reporting with CONNECT XXXX messages. W command options and S95 are enabled X4 Busy and dial tone detection are enabled. Result codes 0-7 are enabled and linespeed reporting with CONNECT XXXX messages. W command options and S95 enabled The @ and W dial modifier result codes are not affected by the X command in effect. The @ dial modifier enables result codes 8 (NO ANSWER) and 7 (BUSY) each time it occurs in the dial string. The W dial modifier enables result codes 6 (NO DIALTONE) and 7 (BUSY) each time it occurs in the dial string. Y -- Long Space Disconnect Options The Y command determines if the modem will disconnect a call upon receiving a long space (1.6 sec break) signal from the distant end. If Y1 is selected, the modem will send a 4-second break (space) before going on hook when an H0 command is issued or, if &D2 is selected, when DTR goes off. Refer also to register S82 for more information. Y0 Disable long space disconnect Y1 Enable long space disconnect Z -- Soft Reset Command The modem can be reset by issuing the Z. The command tells the modem to go on hook and restore the selected stored profile. Any non-storable parameters previously set by commands are returned to their factory settings. The modem aborts execution of all commands following the Z command on the same command line. Subsequent commands on the same line are ignored. Refer to the &W command for description of which modem parameters are included in a stored profile. Z0 recalls stored user profile 0, stored with &W0; Z1 recalls stored user profile 1, stored with &W1. Z0 Recall stored profile 0 Z1 Recall stored profile 1 &B -- V.32 Auto Retrain Options The &B command is used to enable and disable auto retrain in V.32 mode. During a V.32 or a V.22bis connection, the modem continually monitors line quality. The &B command determines whether the modem ignores a line quality problem or attempts to correct the situation by retraining. The selection made with this command affects V.32 connections only. &B and &B0 Disable V.32 Auto Retrain &B1 Enable V.32 Auto Retrain &C -- Data Carrier Detect Options The &C command determines how the state of the DCD lead relates to the carrier from the distant end. The command will take effect immediately when issued. The behavior patterns for DCD depend on the specific &C and &Q commands in effect. Also, DCD patterns depend on whether on-line operation is half or full duplex. Finally, if &Q5 is in effect, DCD behavior depends on whether S10=255 or S10<255. DCD circuit operation is according to the descriptions below. DCD Behaviors for Half-Duplex Operation &C0 &C1 &C2 ---------------------------------------- &Q1 E C C &Q2 E C C &Q3 E C C &Q4 E C C &Q5 A E A &Q5 (S10=255) A C F DCD Behaviors for Full-Duplex Operation &C0 &C1 &C2 ---------------------------------------- &QO A B D &Q1 B B B &Q2 B B B &Q3 B B B &Q4 B B B &Q5 A E A &Q6 A B D &Q5 (S10=255) A B D Table Legend: A - The DCD circuit is ON at all times B - DCD=0 in Idle, DCD tracks carrier in On-Line State with S9: The DCD circuit is OFF while the connection attempt is being made. It goes ON immediately after the CONNECT result code is issued, and goes OFF immediately after loss of remote carrier. If the remote carrier is restored and the S9 (carrier detect response time) delay is completed before the S10 (lost carrier to hang-up) delay expires, then hang-up is avoided and the DCD circuit goes ON again as the modem goes on-line. Otherwise, DCD remains OFF during the hang-up process prior to the result code message. If S10=255, hangup will not occur unless initiated by the DTE. C - DCD=0 in Idle, DCD tracks carrier in On-Line State without S9: The DCD circuit is OFF when the modem is idle. It goes ON immediately after the CONNECT result code is issued, and goes OFF immediately after loss of remote carrier. If the remote carrier is restored, then DCD will go ON regardless of the S9 value in effect. D - DCD=1 in Idle, DCD tracks in On-Line with S9: The DCD circuit is normally ON when the modem is idle, and it is ON while the remote carrier is present and the modem is on-line. The signal goes OFF immediately after loss of remote carrier. If the remote carrier is restored, then DCD will go ON again regardless of S9. If the Hangup Process is initiated by the DTE using DTR or issuing ATH from the on-line state, then DCD will return ON just prior to the modem issuing the OK result code. If S10<255 (lost carrier to hang-up delay) and a timeout equal to S10 expires before the remote carrier is restored, then the hang-up process begins during which DCD=0. DCD will return ON again just prior to the issue of the NO CARRIER result code. If the remote carrier is restored and the S9 delay is completed before the S10 delay expires; then the modem does not hangup, and DCD will go ON again when the modem returns on on-line. E - DCD=0 in Idle, DCD=1 in On-Line State (no tracking): The DCD circuit is OFF when the modem is idle in the command state. DCD goes ON immediately after the CONNECT result code is issued, and it goes OFF when the modem begins the hangup process. DCD does not track the presence of remote carrier energy. F - DCD=1 in Idle, DCD tracks in On-Line without S9: This behavior pattern is associated only with (&C2, &Q5, S10=255, half duplex), and it only occurs at 4800 and 9600 bps in Hayes proprietary V.32 half-duplex operation (Ping Pong). The DCD circuit is normally ON when the modem is operating in half duplex and idle in the command state, and it is ON while the remote carrier is present in the on-line state. It goes OFF approximately 3 seconds after loss of remote carrier. If the remote carrier is restored, then DCD will go ON again (regardless of S9). If the hangup process is initiated by the DTE using DTR or escaping to command state and issuing ATH when on-line, DCD will return ON just prior to the modem issuing the OK result code. The modem will not begin the hangup process if S10=255. &D -- Data Terminal Ready Options The &D command affects how the modem will respond to the state of the DTR signal and changes to this circuit. The effects of DTR states and changes are also very dependent upon the &Q command that is in effect. The test modes associated with certain &T commands are only affected by DTR changes when &D3 is in effect and are not affected by &Q command options. Below, DTR-related behaviors are defined in relation to the &D and &Q commands in effect in smart mode. In dumb mode, the behavior is as defined below for &D2 regardless of the actual &D command in effect. DTR Behaviors in Smart Mode &D0 &D1 &D2 &D3 ----------------------------------------------- &Q0 none E I, H R &Q1 H E I, C, H R &Q2 I, D, H I, D, H I, D, H I, D, R &Q3 I, O, H I, O, H I, O, H I, O, R &Q4 H E I, C, H R &Q5 none E I, S R &Q6 none E I, S R Legend for Table Above Ñ Auto-Answer Function I The DCD circuit is ON at all times. DTR OFF-to-ON Effects: ----------------------------------------------------------------------------- D If S1=0 and in the idle condition, DTR OFF-to-ON signals the modem to go off hook and start the dialing process using the dial string stored by the last &Z0= command. S25 does not affect the modem's reactions to DTR going OFF-to-ON. O If S1=0 and in the idle condition, DTR OFF-to-ON signals the modem to go off hook and start the originate handshake process. S25 does not affect the modem's reactions to DTR going OFF-to-ON. C Following a CONNECT result code, DTR must go ON before the time specified by S25 (in seconds), or CTS will not go ON and the modem will go to the Hangup Process, issue the NO CARRIER result code, at the Response Speed, and go to the idle condition. DTR ONÐtoÐOFF Effects ----------------------------------------------------------------------------- E If in the on-line state, DTR ON-to-OFF signals the modem to exit the on-line state, issue an OK result code at the response speed, and go to command state, while maintaining the connection. DTR transitions to OFF that do not persist more than the time specified by S25 will not cause the modem to exit the on-line state. H If in the on-line state, or in the handshaking, dialing, or answer process, DTR ON-to-OFF signals the modem to execute the hangup process, issue an OK result code at the response speed, and go to the idle condition. The modem is not reset by DTR. This will also abort any dial, handshake, or answer in process. DTR transitions to OFF that do not persist more than the time specified by S25 will not trigger a transition to the hangup process. R DTR ON-to-OFF signals the modem to immediately perform a hard reset regardless of state. All processes are aborted. S25 does not affect the modem's reactions to DTR going OFF-to-ON. There is no result code. S If in On-Line, or in the Handshaking, dialing processes, or answer process, a transition of DTR ON-to-OFF signals the modem to shut down the communications link. When the modem has completed transmitting the data placed into its buffer by the DTE and has completed sending the received data to the DTE, the modem will execute the hangup process, issue an OK result code at the response speed, and remain idle in the command state. The modem is not reset by DTR. This will also abort any dial, handshake, or answer in process. DTR transitions to OFF that do not persist more than the time specified by S25 will not trigger a transition to the hangup process. &F -- Recall Factory Profile The &F command recalls the configuration stored programmed in ROM at the factory. This operation completely replaces the command options and S-Register values in the active configuration with those comprising the factory configuration. For the commands and registers stored and their factory-set values, see the AT Command Set Reference Card accompanying your modem. &G -- Guard Tone Selection The &G command tells the modem which guard tone, if any, to transmit while transmitting in the high band (answer mode). Guard tone is transmitted only while the modem is in the transmitting in the answer mode and during the answer handshake. &G0 Guard tones disabled &G2 1800 Hz guard tone enabled (V.22,V.22bis only) &J -- Jack Type Selection (Auxiliary Relay Options) The &J command designates the type of jack with which the modem is connected to the telephone line. This selection is made by changing the way the auxiliary relay is controlled. The auxiliary relay connects the A lead to the A1 lead, but is normally open. &J0 The auxiliary relay is never closed.(suitable for RJ-11, RJ-41S, or RJ-45S type phone jack) &J1 The auxiliary relay is closed while modem is off hook.(suitable for RJ-12 or RJ-13 type phone jack) &K -- Local Flow Control Options The &Kn command is used to select the local flow control method for use when the modem is operating in error-control mode or asynchronous mode with Automatic Speed Buffering (ASB). ASB is used for communication environments requiring a "Fixed Speed Interface" between the modem and the DTE. S39 stores the current flow control setting. Flow control is always inhibited in command state and is valid only when on-line in error-control mode. Bi- directional flow control regulates the data stream between the DTE and the modem. Specific functions depending on parameter value is as follows: &K0 All flow control is disabled. May be selected for use during error-control mode at the risk of overflowing the buffers and losing data &K1 RTS/CTS flow control is enabled. Note that the DTE-V-series cable must have the supporting wires. The &T19 command may be used by software to determine if the cable is properly wired &K2 XON/XOFF flow control is enabled. These characters are not programmable and are fixed at DC1 and DC3, respectively. This method should not be used when XON/XOFF characters will be sent as user data or as part of a file transfer protocol &K3 RTS/CTS flow control is enabled. Note that the DTE-V-series cable must have the supporting wires. The &T19 command may be used by software to determine if the cable is properly wired &K4 XON/XOFF flow control is enabled. These characters are not programmable and are fixed at DC1 and DC3, respectively. This method should not be used when XON/XOFF characters will be sent as user data or as part of a file transfer protocol &K5 Transparent XON/XOFF The data stream is controlled by characters DC1 and DC3, The chars DLE, DC1, and DC3 are transparentized by sending DLE followed by the character XORed with 21hex &L -- Line Type Selection (Dialup/Leased) The &L1 command instructs the modem to alter its function for leased line environments. The modem will act as if S10=255 and M0 are in effect. It will not dial numbers or send answer tone. The modem must receive an X1D or A command to go on-line. The modem will then go to the dialing or answering process, respectively. Once the handshaking process is completed, the modem tries to stay in the on-line state. When it loses carrier, it returns to the dialing or answering process. Carrier level is determined in one of several techniques, depending on the particular modem. See the Installation Guide for information on setting carrier level. &L0 Select Dial up line operation &L1 Select Leased line operation &O -- PAD Channel Selection The &O command instructs the modem to move from AT command state to a PAD waiting state where it is ready to receive X.25 commands. A Reset operation (see Chapter Two: V-series X.25 Communications) is performed on the selected channel. This command can be issued while off-line so that the PADs may be configured prior to making a connection. &O0 Move to the PAD command state of the last channel accessed (or to channel 1 if no previous channel has been selected) &O1 Move to the PAD command state for channel 1 &O2 Move to the PAD command state for channel 2 &O3 Move to the PAD command state for channel 3 &Q4 Move to the PAD command state for channel 4 &Q -- Communications Mode Options The &Q command selects the communication mode. The &Q command determines how the modem will treat transmitted and received data while in the on-line state (i.e., asynchronous, synchronous, AutoSync, or error-control) and establishes certain call setup procedures. Refer also to the &C, &D, and &S commands in this section. Command On-Line State Special Features ----------------------------------------------------------------------------- &Q0 Asynchronous DCD and DSR behaviors are unique. Refer to &C and &S commands &Q1 Synchronous DTR must be ON after CONNECT when timer value in S25 expires &Q2 Synchronous DTR OFF-to-ON executes dialing process; the D command invalid DTR ON-to-OFF executes the hangup process; the A command is invalid &Q3 Synchronous Dialing and Voice allowed from phone set when DTR is OFF. DTR OFF-to-ON executes the handshaking process (in originate mode); the D command is invalid. DTR ON-to-OFF executes hangup process; the A command invalid &Q4 Hayes AutoSync DTR must be ON after CONNECT when timer equal to S25 expires. DTE data speed is 9600 bps which is not equal to response speed or line speed, yet all result codes are at the response speed &Q5 Error-Control This enables error-control and is unique to V-series system products. Depending upon which V-series system product is being used, any one of several point to point protocols can be negotiated: LAPB, LAPM, X.25 or MNP. After the modem handshake is complete, feature negotiation (see S48) is used to determine which protocol (see S46) will be used for the communication session. If no common protocol is found between the local and remote modems, the fall back options (see S36) will be used &Q6 Buffered Asynchronous Automatic Speed Buffering is useful for DTEs that cannot adjust to changing transmission speeds. This mode ensures the DTE-modem speed is set at a constant rate regardless of the line speed determined during the modem handshake. With the exception of flow control (&Kn) between the DTE and the attached modem, this mode is identical to the standard asynchronous mode (&Q0). ASB operation is also a fall back option (see S36) when the modem is set for error-control mode (&Q5. Because the DTE and DCE speeds are different in ASB, a 256 byte buffer is provided so that flow control does not occur on every character transmission. Some DTEs are sensitive to the buffer size so S-registers are provided to control the lower (S49) and upper (S50) boundaries &R -- RTS/CTS Options The functions of CTS and RTS in synchronous modes (&Q1, &Q2, and &Q3) is determined by the &R command. The &R command has no effect if &Q0, &Q4, &Q5, or &Q6 is in effect. See also the discussion of the CTS and RTS signals in Chapter Three. Refer to the &K command for other RTS and CTS functions. Note when &Q4 is in effect (AutoSync operation), RTS and CTS behaviors are not unlike those specified by EIA 232-D/CCITT V.24. In Synchronous Modes (&Q1, &Q2, and &Q3): ----------------------------------------------------------------------------- &R0 CTS tracks RTS while the modem is in On-Line State and observes the RTS-to-CTS delay determined by S26 &R1 CTS is ON while the modem is in the On-Line State, and RTS is ignored. In Other Modes (&Q0, &Q4, &Q5, and &Q6), the &R option in effect does not control the RTS and CTS functions. &S -- Data Set Ready Options The &S command controls the functions of the DSR circuit. The DSR circuit (pin 6 of the EIA 232-D interface) indicates when the modem is connected a communication channel and is ready. In synchronous mode, when originating a call, DSR goes high when dialing is completed and an answer tone is detected from the remote modem. When answering a synchronous call, DSR goes high when the modem begins transmitting the answer tone. In asynchronous or error-control mode, the &S command can be used to configure the modem to keep the DSR signal high at all times or to have it operate according to the EIA 232-D specification (as described in Chapter Three). When &Q0, &Q5, and &Q6 are in effect: ----------------------------------------------------------------------------- &S0 DSR circuit is always on &S1 DSR=0 in the Idle State and when in a test mode. DSR circuit is turned ON at start of the Handshaking Process. DSR is turned OFF when Hangup Process is started &S2 DSR=0 in the Idle State and when in a test mode. DSR circuit is turned ON at end of handshake prior to issuing of the CONNECT result code. DSR is turned OFF when hangup process is started When &Q1 to &Q4 are in effect: ----------------------------------------------------------------------------- &S0-1 DSR=0 in the command state and at idle. DSR circuit is turned ON at start of the handshaking process. DSR is turned OFF when hangup process is started &S2 &S2- DSR=0 in the command state and at idle. DSR circuit is turned ON at end of handshake prior to issuing of the CONNECT result code. DSR is turned OFF when Hangup Process is started &T -- Test Options The following &T command options are used to configure and place the modem in various test modes as defined by CCITT V.54. These tests can be used to verify the analog and digital portions of the modem's operation, as well as those of the remote modem. Some of these tests require a connection be established before running the procedure. The &T19 command (not a CCITT V.54 test) can be used to test the RTS/CTS functions of the cable used to attach the modem to the DTE. &T0 -- Terminate Test In Process If a V.54 Loopback Test is in process as a result of executing an &Tn command, then the &T0 command will cause that test to be terminated provided that the modem is in the command state, or a V.54 state that accepts commands from the DTE. See specific &T command descriptions for termination actions. &T1 -- Initiate Local Analog Loopback The modem goes on hook and configures itself for analog loopback (using low frequency band if no suffix or "O" suffix, and high frequency band if "A" suffix). DSR is turned off (if &S1 is in effect), the analog loopback state is entered, and the test timer is set to the value in S18. A CONNECT result code is sent to the DTE, and the test timer then begins its count down. The test terminates when the test timer expires. If S18 equals 0, then the test must be terminated by an &T0, H0, or Z command. While any command may be entered while the modem is in this test state, the modem response is not specified except for H0, &T0, and Z -- any of which will terminate the test. Upon termination of the test, the modem enters the command state. Result Codes: Description ----------------------------------------------------------------------------- CONNECT when local analog loopback state is entered ERROR if any other &Tn test is active (except &T0) or if in the On- Line Command State OK after test is stopped by test timer, the H0 command, or the &T0 command &T3 -- Perform Local Digital Loopback The modem must be in the command state with a connection established when this command is issued. Otherwise an ERROR result code occurs. This command establishes a loopback of received data, after demodulation, and sends it back to the distant end. The modem is configured for local digital loopback, DSR is turned off (if &S1 is in effect), the test timer is started with the value in S18, and an OK result code is sent to the DTE . If S18 contains a 0, the test must be terminated by a &T0, H0, or Z command. The latter two result in the modem going on hook. If S18 does not contain 0, the test is terminated after the number of seconds stored in S18. Result Codes: Description ----------------------------------------------------------------------------- OK after 2 s delay ERROR if any other self test is active (&T1,&T6-&T8) or if in Idle State OK when test is terminated &T4 -- Grant RDL Requests When in the On-Line State the modem will honor a remote digital loopback request from a distant modem if it occurs. This will result in an ERROR if the command is given while any V.54 test is active (&T1, &T3, &T6, &T7, or &T8). &T5 -- Deny RDL Requests The modem will not respond to a remote digital loopback request from a distant modem. This will result in an ERROR if the command is given while any V.54 test is active (&T1, &T3, &T6, &T7, or &T8). &T6 -- Initiate Remote Digital Loopback The command is valid only if the modem is in the command state with a connection at 1200 or 2400 bps. The modem sends the remote digital loopback request signal to the distant modem (see CCITT V.22 and V.54). After the RDL acknowledgment signal is received from the distant modem, DSR is turned off (if &S1 is in effect), the on-line state is entered, a CONNECT result code is sent to the DTE, and the test timer is set to the value in S18. If the modem does not receive the RDL acknowledgment signal from the distant end in three seconds, it sends an ERROR result code to the DTE and returns to the command state. The modem sends the signal specified in CCITT V.22 to release the remote digital loopback when the test is terminated. The test may be terminated by the H0, Z, or &T0 command. The test will also terminate when the test timer expires (sending the modem to the command state) or carrier is lost (causing a NO CARRIER result code and the modem to go on hook in the command state). Result Codes: Description ----------------------------------------------------------------------------- CONNECT when On-Line State is entered ERROR if any V.54 test is active (&T1, &T3, &T6-&T8) ERROR if not in On-Line Command State ERROR if command is issued at other than 1200 or 2400 bps ERROR if the RDL signal is not acknowledged &T7 -- Initiate RDL With Self Test The command is only valid if the modem is in the command state with a connection at 1200 or 2400 bps. The modem sends the remote digital loopback request signal to the distant end (see CCITT V.22). After the RDL acknowledgment signal is received from the distant end, DSR is turned off (if &S1 is in effect), the on-line state is entered, an OK result code is sent to the DTE, and the test timer is set to the value in S18. While the test is active the modem sends a test message to the distant end and counts the errors in the received (looped back) signal. The modem stays in the command state during the test. When the test is terminated (except by a loss of carrier), the modem sends the release signal to the distant end, as in &T6, and reports the three-digit error count to the DTE. The information text is followed by an OK result code. See the V command for formats. The test is terminated by loss of carrier, or an H0, &T0, or Z command, and by the S18 timer running out. Result Codes: Description ----------------------------------------------------------------------------- OK when command executed is started OK after error count is sent to DTE ERROR if any other self test is active (&T1,&T3,&T6-&T8) ERROR if not in On-Line Command State ERROR if command is issued at other than 1200 or 2400 bps ERROR if the RDL acknowledgment signal is not received &T8 -- Local Loopback With Self Test The modem goes on hook and is configured for analog loopback (low frequency band if none or O suffix, high frequency band if A suffix). The test timer is started at the time indicated by S18, DSR is turned off (if &S1 is in effect), A selftest condition is entered, and an OK result code is sent to the DTE. During the test the modem sends a test message and counts errors in the looped back signal. The test is terminated when the timer times out (S18) or the &T0, H0, or Z command is issued. When the test is terminated, the three-digit error count is sent to the DTE. An OK result code follows the error count. Result Codes: Description ----------------------------------------------------------------------------- OK if AL Selftest state is entered OK after error count is sent to DTE ERROR if any other V.54 test is active (&T1,&T3,&T6,&T7), or if on-line &T19 -- Perform RTS/CTS Cable Test This test is used to determine whether the DTE-to-DCE cable supports the RTS and CTS signals necessary for hardware flow control. This procedure should be used by software before RTS/CTS flow control (&K3) is used. The modem takes the following action when the &T19 command is issued: 1. Turns OFF CTS (normally ON) and starts a 500 ms timer. 2. Monitors RTS for ON and OFF states. 3. After the 500 ms timeout or when both level-high and level-low states of RTS are detected, the modem restores CTS to the ON condition and ends the test. 4. If both the on and off conditions of RTS are NOT detected, the modem returns the ERROR result code; otherwise, it issues the OK result code. &U -- Trellis Coding Options The &U command is used to enable and disable Trellis coding for V.32 connections. This selection affects V.32 9600 bps transmissions only. &U0 Enable Trellis coding &U1 Disable Trellis coding &V -- View Configuration Profiles The &V command is used to display the active and stored profiles (commands and S-Register settings) along with any stored telephone numbers. Input from the DTE is ignored while this view configuration information is being sent to the DTE. The example below illustrates the &V info-text when the factory profile is loaded and then stored into the stored profiles, and an arbitrary phone number is stored in one of the stored numbers locations. ACTIVE PROFILE: B0 B41 B60 E1 L2 M1 N1 P Q0 V1 W0 X4 Y0 &C0 &D0 &G0 &J0 &K3 &Q5 &R0 &S0 &T4 &U0 &X0 &Y0 S00:000 S01:000 S02:043 S03:013 S04:010 S05:008 S06:002 S07:030 S08:002 S09:006 S10:014 S11:070 S12:050 S18:000 S25:005 S26:001 S36:005 S37:000 S38:020 S44:003 S46:002 S48:007 S49:008 S50:016 S95:000 STORED PROFILE 0: B0 B41 B60 E1 L2 M1 N1 P Q0 V1 W0 X4 Y0 &C0 &D0 &G0 &J0 &K3 &Q5 &R0 &S0 &T4 &U0 &X0 S00:000 S02:043 S06:002 S07:050 S08:002 S09:006 S10:014 S11:095 S12:050 S18:000 S25:005 S26:001 S36:005 S37:000 S38:020 S44:003 S46:002 S48:007 S49:008 S50:016 STORED PROFILE 1: B0 B41 B60 E1 L2 M1 N1 P Q0 V1 W0 X4 Y0 &C0 &D0 &G0 &J0 &K3 &Q5 &R0 &S0 &T4 &U0 &X0 S00:000 S02:043 S06:002 S07:050 S08:002 S09:006 S10:014 S11:095 S12:050 S18:000 S25:005 S26:001 S36:005 S37:000 S38:020 S44:003 S46:002 S48:007 S49:008 S50:016 TELEPHONE NUMBERS: 0= 1=T9W14045551212 2= 3= The three-digit numbers after each S-Register number are decimal representations of the S-Register contents. &W -- Write Active Profile to Memory The &W command stores certain command options and S-Register values into one of the modem's two nonvolatile stored profile memory locations. The command options and register values stored depend on the particular modem. These are indicated on the AT Command Set Reference Card. In addition, the AT speed and parity are stored, according to the values used at the time the command is issued. &W0 Store the Active Profile into Stored Profile 0 &W1 Store the Active Profile into Stored Profile 1 &X -- Synchronous Transmit Clock Source The &X command determines how the DTE transmit clock is generated while the modem is in the synchronous mode. &X0 Modem generates the transmit clock and applies it to pin 15 (EIA 232-D) &X1 DTE generates the transmit clock on pin 24 (EIA 232D) and the modem applies this clock to pin 15 (EIA 232D). This setting is available for external modems only &X2 Modem derives the transmit clock from the receive carrier signal and applies it to pin 15 (EIA 232-D) &Y -- Select Stored Profile For Hard Reset The &Y command selects which stored profile will be copied into the active profile subsequent to a hard reset (including power-up). The &Y command execution is nonvolatile, stored at the time the command is executed, not by the &W command. The value selected with this command is not affected by the &F command, although &Y0 is selected as part of the overall factory setup. &Y0 Select Stored Profile #0 on powerup &Y1 Select Stored Profile #1 on powerup &Zn=x -- Store Telephone Number The &Zn=x command is used to store up to four dialing strings in the modem's nonvolatile memory for later dialing. The format for the command is &Zn="stored number" where n is the location 0-3 to which the number should be written. For example, the line AT&Z2=1552368 writes 1552368 as the third of four possible numbers to the modem's "telephone book" in nonvolatile memory. The &Zn=x command can be used to store a number with as many as 36 characters. Any dialing string can be saved except the S dialing modifier (this would cause a stored dialing string to attempt to dial another stored string), or the ; modifier if used for automatic dialing in synchronous mode 2. If no dial string follows the command, the referenced stored number will be cleared. &Z &Z= &Zn= ... where n=0-3 If the delimiter (=) is not present, the characters following the &Zn=x are treated as telephone numbers and/or modifiers and are stored in location 0. For example, in &Znxxxx, the n is a part of the phone number. If the delimiter is present the characters following it are stored in the location specified by the character preceding the delimiter (which must be in the range 0-3). If no character precedes the delimiter, the number is stored in location 0. If an invalid location is specified (n) the modem sends an ERROR result code. Characters not listed above as storable are ignored. For example, the command &Z1=3456H;AX would store 3456;A. ***************************************************************************** 1.2 Result Code Listing This section defines the result codes returned by Hayes modems in response to commands. The table below shows the various formats in which modem responses can be presented. Note that the "text" of the info-text may consist of multiple lines of text. The formats depicted here only refer to the characters between info-texts and not within them. V0 V1 ------------------------------------------------- Information Text text text Result Codes numeric code verbose code +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1.2.1 Command Response and Call Progress Monitoring This set of result codes includes responses to commands and call progress monitoring responses. They are available to all modems within the capabilities of the modem. For example, the result code CONNECT 9600 is not available to Smartmodem 2400. The factory setting for all high-speed modems enables the extended set of call progress monitoring (X4). When set up in this way, the modem performs and reports full call progress monitoring (RING, NO CARRIER, NO DIALTONE, and BUSY). It also indicates the speed of the connection (CONNECT 1200 as opposed to simply CONNECT). The factory setting for Smartmodem 300, Smartmodem 1200, and all others whose highest speed is 1200 bps is basic call progress monitoring (X0). The command response and call progress monitoring result codes are defined below: 0 -- OK This result code indicates that a command or command string was executed. Note that if more than one command were included on a line and an ERROR result code received, this means that one or more of the commands was not processed. If one or more were executed properly, but even one was invalid, no OK will be issued, only the ERROR. 1 -- CONNECT This result code indicates a connection was made between the DTE and the modem. If X4 (extended set of call progress monitoring) were selected, the code indicates that a connection from at 0 to 300 bps was made. However, if X0 (basic set of call progress monitoring) were selected, the connection could be 0-300, 1200, 1200/75, 75/1200, 2400, 4800, 9600,19200, or 38400 bps. If the modem is not operating in error-control mode, this is the same as the line speed. See other CONNECT messages and CARRIER messages. 2 -- RING This result code indicates the modem as detected a ring signal. No distinction can be made as to whether this is a voice call, a modem call, a fax call, or other type. 3 -- NO CARRIER This result code indicates that no carrier signal was detected, or that the signal was lost. This is the response the modem will give when no connection is made; see CONNECT result code. The modem will also return this message when the connection is broken, either intentionally as when the hangup process completes, or if line difficulties break the connection. 4 -- ERROR This result code indicates that an invalid command was issued, or that there was an error in the command line. For example, if the command line exceeds 40 characters for Smartmodem Products or 255 characters for V-series System Products, this result code will be returned. This result code is also returned in response to the I1 command requesting a ROM checksum, if the modem detects an error in the computation. 5 -- CONNECT 1200 This result code indicates a connection has been established at 1200 or 1200/75, 75/1200, bps between the modem and the DTE. If the modem is not operating in error-control mode, this is the same as the line speed. This result code is disabled by X0. Only CONNECT is reported. 6 -- NO DIALTONE This result code indicates that no dial tone was detected when the modem went off hook. Dial tone detection and this result code are enabled by X2 or X4, or the W dial modifier. 7 -- BUSY This result code indicates that the modem detected a busy signal when it attempted to connect with the modem at the number dialed. Busy signal detection and this result code are enabled by X3 or X4. 8 -- NO ANSWER This result code indicates no silence was detected when dialing a system not providing a dial tone. Enabled by the @ dial modifier. 10 -- CONNECT 2400 This result code indicates a connection has been established at 2400 bps between the modem and the DTE. If the modem is not operating in error-control mode, this is the same as the line speed. This result code is disabled by X0. Only CONNECT is reported. 11 -- CONNECT 4800 This result code indicates a connection has been established at 4800 bps between the modem and the DTE. This result code is disabled by X0. 12 -- CONNECT 9600 This result code indicates a connection has been established at 9600 bps between the modem and the DTE. This result code is disabled by X0. 14 -- CONNECT 19200 This result code indicates a connection has been established at 19200 bps between the modem and the DTE. This result code is disabled by X0. 22 -- CONNECT 1200/75 This result code indicates a connection has been established at 1200 bps when transmitting data and 75 bps when receiving data between the modem and the DTE. 23 -- CONNECT 75/1200 This result code indicates a connection has been established at 75 bps when transmitting data and 1200 bps when receiving data between the modem and the DTE. 28 -- CONNECT 38400 This result code indicates a connection has been established at 38400 bps between the modem and the DTE. This result code is disabled by X0. +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1.2.2 Negotiation Progress Messages V-series system products report special result codes during error-control negotiation. Whether or not these messages are displayed is selected with the W command (not to be confused with the W dial modifier). The factory setting is messages disabled (W0) to avoid conflict with software programs that do not support this additional level of call progress monitoring. 40 -- CARRIER 300 This message indicates that a carrier signal has been detected at 300 bps (modem-to-modem line speed). 44 -- CARRIER 1200/75 This message indicates that a carrier signal has been detected at 1200 bps when transmitting and at 75 when receiving (modem-to-modem line speed). 45 -- CARRIER 75/1200 This message indicates that a carrier signal has been detected at 75 bps when transmitting and at 1200 bps when receiving (modem-to-modem line speed). 46 -- CARRIER 1200 This message indicates that a carrier signal has been detected at 1200 bps (modem-to-modem line speed). 47 -- CARRIER 2400 This message indicates that a carrier signal has been detected at 2400 bps (modem-to-modem line speed). 48 -- CARRIER 4800 This message indicates that a carrier signal has been detected at 4800 bps (modem-to-modem line speed). 50 -- CARRIER 9600 This message indicates that a carrier signal has been detected at 9600 bps (modem-to-modem line speed). 66 -- COMPRESSION: CLASS 5 This message indicates that data compression using MNP Class 5 has been negotiated for the connection. 67 -- COMPRESSION: V.42BIS This message indicates that data compression using CCITT V.42bis has been negotiated for the connection. 68 -- COMPRESSION: ADC This message indicates that data compression using Hayes Adaptive Data Compression has been negotiated for the connection. 69 -- COMPRESSION: NONE This message indicates that data compression was not negotiated for the connection. 70 -- PROTOCOL: NONE This message indicates that no protocol was negotiated for the connection. A standard asynchronous connection was made. 71 -- PROTOCOL: ERROR-CONTROL/LAP-B This message indicates that an error-control connection was negotiated with LAPB protocol. This protocol is the one used by the first V-series System Products. 72 -- PROTOCOL: ERROR-CONTROL/ LAP-B/HDX This message indicates that a half-duplex error-control connection was negotiated with LAPB protocol. This protocol is the one used by the first V- series System Products communicating at 9600 bps. 73 -- PROTOCOL: ERROR-CONTROL/LAP-B/AFT This message indicates that an error-control connection was negotiated using the Hayes Asynchronous Framing Technique. This protocol is used for connections between modems such as Smartmodem 1200 that do not communicate synchronously across the telephone line. AFT enables an error-control protocol to be used. 74 -- PROTOCOL: X.25/LAP-B This message indicates that an error-control connection using the X.25 protocol was established with a carrier speed of 1200, 2400, 4800, or 9600 bps. 75 -- PROTOCOL: X.25/LAP-B/HDX This message indicates that a half-duplex error-control connection using the X.25 protocol was established with a carrier speed of 4800 or 9600 bps. 76 -- PROTOCOL: X.25/LAP-B/AFT This message indicates that an asynchronous error-control connection using the X.25 protocol was established with a carrier speed of 1200 bps. The Hayes Asynchronous Framing Technique was used. 77 -- PROTOCOL: LAP-M This message indicates that an error-control connection using the V.42 LAPM protocol was established with a carrier speed of 1200, 2400, 4800, or 9600 bps. 78 -- PROTOCOL: LAP-M/HDX V.42 This message indicates that a half-duplex error-control connection using the V.42 LAPM protocol was established with a carrier speed of 4800 or 9600 bps. 79 -- PROTOCOL: LAP-M/AFT This message indicates that an asynchronous error-control connection using the V.42 LAPM protocol was established with a carrier speed of 1200 bps. The Hayes Asynchronous Framing Technique was used. 80 -- PROTOCOL: ALT This message indicates that an error-control connection using the V.42 LAPM alternative protocol was established with a carrier speed of 1200, 2400, 4800, or 9600 bps. This protocol is MNP Classes 2, 3, and 4 compatible. 91 -- AUTOSTREAM: LEVEL 1 This message indicates that Hayes AutoStream Level 1 has been negotiated for the connection. This technique provides for multiplexing of multiple virtual channels. 92 -- AUTOSTREAM: LEVEL 2 This message indicates that Hayes AutoStream Level 2 has been negotiated for the connection. This technique provides for multiplexing of multiple virtual channels, with transparent control of one PAD (non-simultaneous). 93 -- AUTOSTREAM: LEVEL 3 This message indicates that Hayes AutoStream Level 3 has been negotiated for the connection. This technique provides for multiplexing of multiple virtual channels, with transparent control of all PADs (simultaneous). Negotiation progress messages are reported in the following order: CARRIER PROTOCOL AUTOSTREAM COMPRESSION CONNECT If AutoStream is not used, no message is reported. +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1.2.3 Information Text (INFO-TEXT) Some commands, such as &V and Sr? return information text as opposed to numeric or verbose codes. The alpha characters are headings and commands and the numbers are command options, ASCII values, counter values, etc. The example below illustrates a modem response to a command with information text. ACTIVE PROFILE: B0 B41 B60 E1 L2 M1 N1 P Q0 V1 W0 X4 Y0 &C0 &D0 &G0 &J0 &K3 &Q5 &R0 &S0 &T4 &U0 &X0 &Y0 S00:000 S01:000 S02:043 S03:013 S04:010 S05:008 S06:002 S07:030 S08:002 S09:006 S10:014 S11:070 S12:050 S18:000 S25:005 S26:001 S36:005 S37:000 S38:020 S44:003 S46:002 S48:007 S49:008 S50:016 S95:000 Information Text is always a combination of alpha and numeric. The V command has no effect on the format of this command response. ***************************************************************************** 1.3 S-Register Listing The following definitions include all S-Registers defined for the various families of Hayes modems. Some factory settings and ranges are included here because they are almost universally implemented with these values; however, be sure to consult the AT Command Set Reference Card that came with your modem for the S-Registers and their ranges/factory settings that your modem supports. Note that register numbers not included in this listing are those for which no function has been assigned. S0 -- Ring to Answer After S0 sets the ring number on which the modem automatically answers a call when auto-answer mode is selected. S0=0, the factory setting, disables auto- answer. S1 -- Ring Count When the modem is in the command state and set for auto-answer (Register S0>0), the modem automatically tracks the number of times the phone rings, incrementing and writing the value in S1. The value reverts to 0 if no ring occurs for 8 seconds. Once a connection is made, the modem resets the value of this register to 0. Note that two short ring bursts within a ring cycle are counted as two rings. S2 -- Escape Sequence Character This register holds the ASCII value of the escape sequence character. The factory-set value is ASCII 43, the plus sign (+). The value for this register can be set to any ASCII value between 0 and 127. Setting S2 to a value greater than 127 disables the escape sequence, preventing the modem from returning to the command state and disabling command recognition. S3 -- Carriage Return Character This register holds the ASCII value of the line terminating character. The factory-set value is ASCII 13 -- carriage return () -- the range for the register is 0-127. This character is used both as the command line terminator and the result code terminator. S4 -- Line Feed Character This register holds the ASCII value of the line feed character. The factory setting is 10; the range is 0-127. S5 -- Backspace Character This register holds the ASCII value of the backspace character. The factory- set value is ASCII 08; the range for the register is 0-32, 127. This character moves the cursor left, removing the previous character. As this value actually represents the combined operation of three characters (a backspace, a space, and another backspace), the time allotted to process the backspace character must not be any less than the time required by the modem to transmit three characters. For this reason, a repeat-key function may not operate properly on backspaces. S6 -- Wait Before Blind Dialing This register determines how long the modem waits after going off-hook before it dials. This delay allows time for the central telephone office to detect the off-hook condition of the line and apply dial tone. This wait time only applies to the first dial tone. S6 is used only if X0, X1, or X3 is selected. Selecting X3 or X4 enables dial tone (call progress) detection and disables blind dialing, thus making the setting of S6 irrelevant. The value of this register can be set for any number from 4 through 7 seconds. This feature allows you to increase the time delay if you have difficulty obtaining dial tone within 4 seconds. Note: The Wait Before Blind Dialing call progress monitoring feature (W dial modifier) applies only to detection of a second dial tone and is independent of any S-Register settings. S7 -- Wait for Carrier after Dialing This register determines the modem's time delay between dialing and responding to an incoming carrier signal after initial connection. If the modem does not detect a carrier within this time, the modem hangs up and returns the NO CARRIER result code. If the modem detects a carrier within the specified time, it goes on line. S8 -- Duration of Delay for Comma Dial Modifier This register determines the duration of the delay generated by the comma (,) dial modifier. S9 -- Carrier Detect Response Time This register determines how many seconds a carrier signal must be present for the modem to recognize it and issue a carrier detect. The value for the register is measured in tenths of a second. The factory setting is 6 (0.6 second); the range is 1 (0.1 second) to 255 (25.5 seconds). Note: The S9 value affects the time required to recognize the presence of carrier only if X3 or X4 is selected. The modem also ignores the value in register S9 when operating in half-duplex synchronous or asynchronous mode. S10 -- Delay Between Lost Carrier and Hang Up This register specifies the time between loss of remote carrier and local modem disconnect. The delay permits the carrier to disappear momentarily without causing the modem to hang up. The value for the register is measured in tenths of a second. The range for most modems is 1 (0.1 second) to 255 (25.5 seconds). The modem recognizes a carrier after the period of time specified in S9. Therefore, if the value of S10 is less than that set for S9, even a momentary loss of carrier will cause the modem to disconnect. Setting the register to 255 causes the modem to ignore actual carrier status and assume a carrier is always present. When operating in half-duplex synchronous mode, the modem ignores the value of this register. S11 -- Multi-Frequency Tone Duration This register determines the duration and spacing of tones in multi-frequency tone dialing. The value in this register has no effect on the speed of pulse dialing. S12 -- Escape Sequence Guard Time This register holds the value of the delay required prior to and following the escape sequence. The guard time also dictates how quickly the escape sequence characters must be entered, since the interval between entry of each of the three characters must be of shorter duration than that specified for the guard time. If guard time is set to 0, timing is not a factor. S18 -- Modem Test Timer This register establishes the duration of the modem's diagnostic tests. When a test is active for a length of time equal to the value chosen for this register, the modem automatically terminates the test. A setting of zero (0) disables the test timer (factory setting). The range for this register is 0- 255 seconds. S25 -- DTR Detection This register serves two purposes. When the modem is operating in synchronous mode 4, the value assigned to S25 specifies the length of time the modem waits after a connection has been made, before examining the DTR circuit. This allows the modem to ignore an on-to-off transition of DTR and gives the user sufficient time to disconnect the modem from the asynchronous terminal and attach it to a synchronous terminal, without forcing the modem back to the asynchronous command state. During this time, the value of S25 is read in full seconds (e.g., the factory- set value of 5 equals 5 seconds, instead of 0.05 seconds). In all other modes, and after call establishment in synchronous mode 4, the value is read in 1/100 seconds. In any mode, a change in DTR (on or off) that persists for a period shorter than the value held in S25 is ignored by the modem while it is on-line. The range of values for S25 is 0-255. S26 -- RTS to CTS Interval This register is used to specify the interval to delay before turning on CTS after an off-to-on transition of RTS. This value takes effect when the &R0 command option has been selected. This setting applies to synchronous modes 1, 2, and 3 only. The factory-set value is 1 (.01 seconds) with a range of 0-255. S30 -- Inactivity Timeout This register monitors the line to prevent unnecessary connection time. If no data transfer is detected (while the modem is in the on-line state) for a duration specified by this register, the modem hangs up and returns to the idle state. When the value of S30 is set to 0, the timer is disabled. The factory setting is 0 seconds; the range is 0-255 units of 10 seconds. Note that S30 is only effective in &Q0 or &Q6 modes; it is not enabled in any synchronous modes. S33 -- AFT Options Register S33 applies only to communications using a V-series Modem Enhancer(TM) with a Smartmodem 1200 which has an asynchronous DTE link. This register selects the options to be used with Hayes Asynchronous Framing Technique (See the description of S44. AFT offers options to prevent certain characters (like XON and XOFF) from being sent. Normally AFT uses all 256 ASCII character codes; that is, it uses characters with 8 data bits. If intervening equipment is limited to 7-bit operation, the Eight-Bit Data Transparency option (S33=4) can be enabled. With this option, AFT limits itself to using characters with 7 data bits. This pertains only to the communication link between the two modems, not the format of the data. The data itself is unaffected by enabling any AFT transparency options. 0 No transparency options required (factory setting) 1 Flow Control Transparency. AFT transparentizes the XON and XOFF control characters sent from the DTE to the modem. The XON and XOFF characters themselves are not sent over the communication link; characters that substitute for these functions are transmitted, instead 2 Select Control Character Transparency 4 Select Eight-Bit Data Transparency 5 Select both Flow Control Transparency and Eight-Bit Data Transparency 6 Select both Control Character Transparency and Eight-Bit Data Transparency If feature negotiation is active, the transparency option selected by one modem is used by both modems. S36 -- Negotiation Failure Treatment When an attempt to make an error-control connection fails, the modem reads this register to determine whether to terminate the connection, make an asynchronous connection (otherwise selected with &Q0), or make an asynchronous connection with ASB (otherwise selected with &Q6). This register is referenced only when the error-control mode has been selected with the &Q5 command (factory setting) and this communication mode cannot be negotiated. 0 Hang up 1 Attempt a standard asynchronous connection (&Q0) 3 Attempt an asynchronous connection using automatic speed buffering (&Q6) 4 Attempt a V.42 Alternative Protocol connection (MNP compatible); if negotiation fails, hang up. 5 Attempt a V.42 Alternative Protocol connection (MNP compatible); if negotiation fails, attempt a standard asynchronous connection 7 Attempt a V.42 Alternative Protocol connection (MNP compatible); if negotiation fails, attempt an asynchronous connection using automatic speed buffering In asynchronous mode, the CONNECT XXXX message will be returned with a successful connection. This message indicates the speed of the connection, which is also the speed of data transmitted from computer to modem. Note: The selected fallback option can be initiated immediately with S48. For example, a connection attempt using the Alternative Protocol can be forced by setting S48=128 and S36=5 or 7. S37 -- Desired DCE Line Speed The modem attempts to connect with a remote modem at the highest supported DCE speed that does not exceed the value specified by this register. If S37 is set to a speed higher than that supported by the modem, it will attempt to connect at its highest capability. 0 Attempt to connect at speed of last AT command issued 1 Attempt to connect at 75 bps 2 Attempt to connect at 110 bps 3 Attempt to connect at 300 bps 4 Reserved 5 Attempt to connect at 1200 bps 6 Attempt to connect at 2400 bps 7 Attempt to connect at 4800 bps 8 Reserved 9 Attempt to connect at 9600 bps Note that this is the speed of modems across the telephone line, not the speed at which the modem communicates with the attached DTE. S38 -- Delay Before Forced Hang up This register specifies the delay between the modem's receipt of the command to hang up (or on-to-off transition of DTR if the modem is configured to follow the signal) and the disconnect operation. This register is useful for error-control communications to ensure that data in the modem buffers is sent before the connection is terminated. The factory setting is 20 (seconds). If this register is set between 0 and 254, the modem will wait that number of seconds for the remote modem to acknowledge receipt of all data in buffers before hanging up. If this timeout occurs before all data can be sent, the NO CARRIER (3) result code will be sent to indicate that data has been lost. If all data is transmitted prior to the timeout, the response to the H0 command will be OK. If S38 is set to 255, the modem does not timeout, and continues to attempt to deliver data in buffers until the connection is lost, or the data is delivered. S44 -- Asynchronous Framing Technique Selection S44 sets the use of the Hayes Asynchronous Framing Technique. Connections to a packet switched network or between two error-control modems using either Error-Control/LAP-B or X.25 protocol are usually synchronous connections, even though the user interface is always asynchronous. Some environments may require asynchronous to synchronous conversion in the protocol because equipment is limited to asynchronous operation, or an asynchronous to synchronous conversion is already in place. For example, most Hayes 1200 bps modems support only asynchronous communication over the telephone line. When one of these modems is connected to a V-series Modem Enhancer, the interface between the two is always asynchronous. A feature provided by the V-series Modem Enhancer called the Asynchronous Framing Technique (AFT) makes this possible. When AFT is enabled, the output of the error-control protocol is asynchronous instead of synchronous. Register S44 applies only to communications using a V-series Modem Enhancer with a Smartmodem 1200 that connects using an asynchronous link across the telephone line. 2 Use AFT. When AFT is selected, the data output is asynchronous instead of synchronous. AFT is required if the path your call takes passes through asynchronous-only equipment. 3 The modem to automatically selects whether or not to use AFT. V-series Modem Enhancer, when connected to a Smartmodem 1200, automatically uses AFT (factory setting). If the modem is configured to use feature negotiation, and the other modem is using AFT, both modems automatically select AFT. S46 -- Error-Control Protocol Selection This register specifies the error-control method used for subsequent connections. A V-series System Product supports at least one additional protocol. Because the factory setting will be a protocol for point-to-point communications, other connections, such as the X.25 protocol must be enabled by setting S46. Feature negotiation enables two communicating modems to identify the common protocols, and choose one based on the user-configuration for the communication session. For example, if a V-series System Product is configured to use the X.25 protocol, but connects with a V-series System Product without X.25 capability, an error-control protocol is automatically selected because both modems support it. However, if a V-series System Product with X.25 connects with another V-series System Product with X.25, both can use X.25 protocol if configured to do so (S46=6). When attempting a connection to a packet switched network, automatic feature negotiation is usually disabled because unless an X.25 connection can be made, further network connections cannot be made. To disable automatic feature negotiation and make an X.25 connection or hang up, set S46=134. The options for this register are described below: 0 Either LAPM or fallback to LAPB 1 LAPB only 2 LAPM or fallback to LAPB; use data compression# 3 LAPB with data compression# 6 X.25 or fallback to LAPB; use data compression# 136 LAPM only 138 LAPM with data compression# 134 X.25 # The technique negotiated is determined by capabilities and configuration of both modems. V.42bis is attempted first, then Hayes Adaptive Data Compression. If neither method is supported by both modems, or if either modem has compression disabled, no compression will be used. S48 -- Enabling/Disabling Feature Negotiation This register selects how feature negotiation is used when making connections with the remote system. The negotiation process can be tailored to suit a connection, or bypassed altogether. For example, when the capabilities of the remote modem are known, negotiation is unnecessary. The factory setting is 7, negotiation enabled. With feature negotiation disabled, the V-series System Product assumes that the remote modem is configured the same as itself, and proceeds to activate the error-control protocol specified by the S46 (protocol options) setting. Use 128 when calling a packet switched network that does not support feature negotiation. 0 Negotiation disabled; presume the remote modem is configured for and has the capabilities necessary for the connection selected with S46 3 Negotiation enabled, but originating modem remains silent during detection phase. For connections with MNP modems; however, this setting defeats the negotiation sequence with other V.42 modems 7 Negotiation enabled 128 Negotiation disabled; forces fallback options specified in S36 to be taken immediately S49 -- ASB buffer size lower limit This register sets the lower limit of the modem's buffer when communicating in asynchronous mode with ASB. The range of this register is 1-249. The factory setting is 8 bytes. S50 -- ASB buffer size upper limit This register sets the upper limit of the modem's buffer when communicating in asynchronous mode with ASB. The range of this register is 2-250 bytes. The factory setting is 16 bytes. S53 -- Global PAD Configuration S53 defines a set of behavior switches that control the PAD and all four channels in the V-series System Product. This fixed user interface provides software and users with a consistent PAD command interface regardless of current PAD parameter settings. The fixed user interface is effective in all states except the on-line (data transfer) state. For example, the factory-set value of PAD parameter 2 is zero, which turns off character echo. This is required for a transparent on-line state (e.g., for Smartmodem product emulation). However, since it may be difficult to enter PAD commands without seeing them echoed at your terminal, a method of controlling the PAD despite the parameter settings would be necessary. The fixed user interface affects the following in all states, except the on- line state: * Transmission of all PAD result codes, including the prompt PAD result code * Echo control via the E command * Fixed editing characters (delete character is defined by S5, delete line character is Control-X, line display character is Control-R) * Echo mask masks only the editing characters The fixed PAD control interface affects the following in all states: * Disables PAD recall using a character (PAD parameter 1) or a break signal * Disables all PAD flow control (PAD parameters 5, 12) * Disables carriage return (PAD parameter 9) and line feed (PAD parameter 14) padding * Disables line folding (PAD parameter 10) * Existing result codes use result codes for terminal (PAD parameter 19) * Disables page wait (PAD parameter 22) * Disables execution of ANS and EXEC strings * Disables EXEC command If the value of S53 includes any bit value except 1, the PAD prompt character changes from * to -. The change in the prompt PAD character provides an indication that the PAD is not in CCITT mode. The register's values are provided below: 0 Normal CCITT-compatibility mode 1 Normal CCITT-compatibility mode. PAD prompt is an asterisk (*) and appears with the channel number (e.g., 1*). 2 Fixed user interface. PAD prompt is a hyphen (-) 3 Fixed user interface. PAD prompt is a hyphen and appears with the channel number (e.g., 1-) (factory setting) 4 Fixed control interface. PAD prompt is a hyphen 5 Fixed control interface. PAD prompt is a hyphen and appears with the channel number 6 Fixed user and fixed control interface. PAD prompt is a hyphen 7 Fixed user and fixed control interface. PAD prompt is a hyphen and appears with the channel number S63 -- Leased line carrier level This register selects the carrier power level in dBm for leased line operation. This register specifies a nominal carrier level value. The range for this register is 0-15 (0 dBm to -15 dBm). The factory setting is 0. Note that for those modems supporting leased line operation, carrier level (if adjustable) may be set by other means. Please refer to the modem's Installation Guide for information. S69 -- Link Layer Window Size This register sets the number of frames (packets) sent between acknowledgements from the remote system. Each frame is one packet and the window size is how many frames you can send before you must stop and wait for the remote end to send an acknowledgement that it received the frames and is ready to receive more frames. The range is 1-15 with a factory setting of 15. LAPM connections use a window size of 1-15; LAPB connections and X.25 connections use a window size of 1-8. If a LAPB or X.25 connection is made, any value greater than 8 is treated as 8. Reducing window size can reduce performance. Reduce the window size only when so instructed by the network (this rarely occurs). S70 -- Maximum Number of Retransmissions S70 limits the number of times the modem will retransmit a frame. Retransmissions become necessary when data errors introduced by noise disrupt the reception of a frame. When the limit set by S70 is reached, the modem hangs up. Raising this limit may be necessary if, for example, telephone lines are extremely noisy. The retransmission delays may be undesirable, but the modem will not hang up. The range for this register is 0-255, with a factory setting of 10. S71 -- Link Layer Timeout When the link layer sends a character, it starts a timer referenced in the formula below as "T1." If the remote end does not respond after T1 seconds, the link layer retransmits. The value of T1 is computed automatically based on the connection speed and maximum packet size. T1 = 2 * (maximum packet size + 11) * (8 Ö bits per second) + T2 + 500 msec The S71 setting is represented by the "T2" in the formula. The setting affords some control over the final value of T1. You can increase T1 by increasing T2. You may want to do this if your communication environment has unusually long delays transmitting information from one end to the another (such as with satellite connections), or if the computer at the other end takes a long time to respond. The range for this register is 1-255 milliseconds, with a factory setting of 20.. S72 -- Loss of Flag Idle Timeout A transmitter not currently sending data to send is described as "idle." Normally, idle transmitters send a repeating pattern called "flag idle." Your modem always monitors the line to make sure the remote end of the communication link is either sending data or a flag idle. This ensures that the modem is operating. S72 determines how long the local modem waits before hanging up when it no longer is receiving data or a flag idle. In some systems, periods of "mark idle" (periods where all ones are transmitted instead of the flag pattern) are normal. When using such a system, it may be necessary to increase the value in S72. If the register is set to 0, this monitoring function is disabled. The range for this register is 1-255 seconds; the factory setting is 30. S73 -- No Activity Timeout If your modem is receiving good carrier and flag idle from the remote modem but does not receive any data for the time period specified by S73, it will send a query (called an "RR") to the remote modem to make sure the modem is operating properly. The range for this register is 1-255 seconds; the factory setting for this register is 5. Decreasing this value causes the modem to test more frequently for malfunctions at the remote end. However, the modem will not hang up for approximately 2 * T1 * N2 seconds because it retransmits the RR query several times. A Note on Registers S74, S75, S76, S77, S78, and S79 (Logical Channel Number Selectors) Although V-series System Products supports four virtual channels, numbered 1 through 4, packet switched networks can support up to 4096 channels (numbered 0-4095). Each network has its own channel numbering system to support multiple users. For example, if there are 15 calls, each with four virtual connections, the packet switched network can support all 60 (4*15) virtual calls, but each has to have a different logical channel number. Networks often set up their system so that all incoming calls are within one range and all outgoing calls are within another range. Logical Channel Numbers are automatically assigned by the V-series System Product, but the ranges need to be configurable in order to be compatible with different network requirements. S74, S75 -- Minimum Incoming Logical Channel Number (LCN) S74 and S75 combine to specify the lowest incoming Logical Channel Number the packet layer will report or accept. The value used is formed by using S74 as the two high decimal digits and S75 as the two low decimal digits, or the value can be expressed by the formula S74*100+S75. If the resulting value is outside the range (0-4095), the value is assigned to the appropriate corresponding limit (e.g., if a value of 4099 is used, it is assigned to the upper limit value of 4095). S74=0 Factory setting from a range of 0-40 S75=1 Factory setting from a range of 0-99 S76, S77 -- Maximum Incoming Logical Channel Number (LCN) S76 and S77 combine to specify the highest incoming Logical Channel Number the packet layer will report or accept. The value used is formed by using S76 as the high two decimal digits and S77 as the two low decimal digits, or the value can be expressed by the formula S76*100+S77. If the resulting value is outside the range (0-4095), the value is assigned to the appropriate corresponding limit (e.g., if a value of 4099 is used, it is assigned to the upper limit value of 4095). S76=40 Factory setting from a range of 0-40 S77=95 Factory setting from a range of 0-99 S78, S79 -- Outgoing Logical Channel Number (LCN) The setting of registers S78 and S79 should be adjusted if the network requires a range of Logical Channel Numbers outside those specified with the combination of these two registers. S78 and S79 combine to determine the outgoing Logical Channel Number the packet layer will use to place a call. The value is derived using S78 as the two high decimal digits and S79 as the low two decimal digits, or the value can be expressed by the formula S78 * 100 + S79. If the resulting value is outside the range (4-4095), the value is then assigned to the appropriate limit. The highest Logical Channel Number would be that derived from the above formula, and the lowest would be the value minus the maximum number of channels supported plus one. The user has the ability to override this factory setting and explicitly specify an LCN using the PAD selection command (CALL). S78=0 Factory setting from a range of 0-40 S79=16 Factory setting from a range of 0-99 A Note on Registers S80 and S81 (Packet Layer Parameters) The values in these two registers combine to set time and duration for packet layer restart requests. S80 -- Packet Layer N20 Parameter This register sets the maximum number of times a restart request can be retransmitted. The factory setting is 1 (S80=1) from a range of 0-255. Setting this register may be necessary if the network requires a restart attempt to abandon a connection earlier than planned. S81 -- Packet Layer T20 Parameter This register sets the maximum amount of time the transmitter will wait for acknowledgment of a restart request frame before initiating a recovery procedure, in 10-second increments. The factory setting is 18 from a range of 0-255. Setting this register may be necessary if the network requires a restart attempt to abandon a connection earlier than planned. S82 -- Break Signaling Technique This register selects a method of break signal handling for V.42 communications: in sequence, expedited, and destructive. Break signals provide a way for you to get the attention of the remote host. The break type used depends on your application. 3 Expedited signaling regardless of its sequence in data sent and received; data integrity maintained 7 Destructive signaling regardless of its sequence in data sent and received; data in process at time is destroyed 128 In sequence signaling as data is sent and received; data integrity maintained ahead of and after break S84 -- Adaptive start up negotiation (ASU) This register selects the adaptive start up method to be negotiated for subsequent connections. 0 Do not negotiate ASU connection 128 Negotiate ASU with fixed start up 129 Negotiate ASU with fast start up on both sides 130 Negotiate ASU with smooth start up on both sides 131 Negotiate ASU with configuring modem using fast start up and the other modem using smooth start up 132 Negotiate ASU with configuring modem using smooth start up and the other modem using fast start up S85 -- ASU Negotiation Report This register indicates whether adaptive start up and method were negotiated for the current connection. To read this register, issue the escape sequence to place the modem in the command state, then issue ATS85? . The modem will report one of the values below. 0 ASU not negotiated; fixed start up in use 128 ASU negotiated with fixed start up 129 ASU negotiated with fast start up on both sides 130 ASU negotiated with smooth start up on both sides 131 ASU negotiated with reporting modem using fast start up and the other modem using smooth start up 132 ASU negotiated with reporting modem using smooth start up and the other modem using fast start up S86 -- Connection Failure Cause This register can help you determine the cause of a connection failure. When the modem issues a NO CARRIER result code, a value is written to this register. To read this register, following the connection failure, issue ATS86? . The modem will report one of the values below. 0 Normal hang up; no error occurred 4 Physical carrier loss 5 Feature negotiation failed to detect presence of another error-control modem at the other end 6 Other error-control modem did not respond to feature negotiation message sent by this modem 7 Other modem is synchronous-only; this modem is asynchronous-only 8 Modems could not find a common framing technique 9 Modems could not find a protocol in common 10 Feature negotiation message sent by other modem incorrect 11 Synchronous information (data or flags) not received from other modem. Modem waited 30 seconds before hanging up 12 Normal disconnect initiated by other modem 13 Other modem did not respond after many transmissions of the same message. Modem made 10 attempts then hung up 14 Protocol violation occurred 15 Compression failure Note: Multiple occurrences may contribute to a NO CARRIER message; S86 records the first event that occurred. S92 -- MI/MIC Options This register enables (chooses method) or disables the mode indicate/mode indicate common interface. The settings available for this register support various combinations of edge and level detection in either originate or answer mode with ring indicator (RI) pulse enabled or disabled. For particulars as to how the jack setting specified with the &J command interacts with this register, see the modem's Installation Guide. 0 MI/MIC disabled 1 level triggered, originate mode, RI pulse enabled 3 edge triggered, originate mode, RI pulse enabled 5 level triggered, answer mode, RI pulse enabled 7 edge triggered, answer mode, RI pulse enabled 9 level triggered, originate mode, RI pulse disabled 11 edge triggered, originate mode, RI pulse disabled 13 level triggered, answer mode, RI pulse disabled 15 edge triggered, answer mode, RI pulse disabled Note that this feature is not available to all modems. Refer to the feature list in the modem's Installation Guide. S93 -- V.25bis DTE interface speed This register selects the speed used when the modem is configured for V.25bis mode. When autobauding in any mode other than V.25bis, the modem uses the value held in S37. 3 300 bps 5 1200 bps 6 2400 bps 7 4800 bps 9 9600 bps Note that the V.25bis feature is not available to all modems. Refer to the feature list in the modem's Installation Guide. S94 -- Command Mode Selector This register provides an alternative to setting internal DIP switches when choosing between the AT command mode (factory setting) and the various CCITT V.25bis command modes supported by the modem. To use this register, DIP switches 3 and 4 must both be in the UP position (factory setting). If switches 3 and 4 are both UP, the operating mode after a soft reset is determined by S94. This register is read from nonvolatile memory at power-on; the &W command saves the current setting of this register in nonvolatile memory. Here are the values for S94: (Synch) (Synch) Value Sync/ AT/ Addressed/ HDLC/ ASCII/ Async V.25bis Direct BSC EBCDIC --------------------------------------------------------- 0 Async AT -- -- -- 1 Async V.25bis Addressed -- -- 2 Sync V.25bis Addres HDLC ASCII 3 Sync V.25bis Addressed BSC ASCII 4 Async AT -- -- -- 5 Async V.25bis Direct -- -- 6 Sync V.25bis Direct HDLC ASCII 7 Sync V.25bis Direct BSC ASCII 8 Async AT -- -- -- 9 Async V.25bis Addressed -- -- 10 Sync V.25bis Addressed HDLC EBCDIC 11 Sync V.25bis Addressed BSC EBCDIC 12 Async AT -- -- -- 13 Async V.25bis Direct -- -- 14 Sync V.25bis Direct HDLC EBCDIC 15 Sync V.25bis Direct BSC EBCDIC An alternative way of presenting the V.25bis mode selection options listed above follows: Value Mode --------------------------------------------------------- 0 Standard AT command operation (factory setting) 1 Asynchronous V.25bis using addressed access 2 Synchronous V.25bis (HDLC framing) using addressed access 3 Synchronous V.25bis (BSC framing) using addressed access +4 Direct access calling procedure +8 EBCDIC character set options instead of ASCII S95 -- Negotiation Message Options This register enables various result codes that indicate the sequence of events in the establishment of an error-control connection. This register does not affect the way in which the modem negotiates the connection; it merely enables message options. The factory setting for this register is value 0, no bits selected. To enable any combination of the bits, add the value(s) to the right of the bit number and set the register to this sum. Note: The bit values of S95 may be set to override some of the characteristics of the Wn command. Setting any of the S95 bits to "1" enables the corresponding result codes regardless of the Wn command in effect. Changing the Wn command setting does not affect the value set for this register. Bit Value Explanation 0 1 Verbose CONNECT result code indicates the DCE speed (rather than DTE speed). Numeric result codes are also differennt when CONNECT reports DCE speed. 1 2 Append "/ARQ" to CONNECT result code when an error-control connection is made 2 4 Add CARRIER messages 3 8 Add PROTOCOL messages 4 16 Add AUTOSTREAM messages 5 32 Add COMPRESSION messages For example, if you want to add the compression result code (with W1 selected), you would select bit 5 (value of 32). The command line ATS95=32 will then enable the COMPRESSION negotiation messages. Refer to the Wn and Xn commands for additional and related information. S97 - V.32 Automdode V.22/V.22bis Probe Timing S97 sets the duration of the signal used by the modem in the answer mode during a V.32 automode handshake to determine if the calling modem is of V.22 or V.22bis type. The value of S97 also sets the time during which the modem will reject the V.22/V.22bis probe signal when executing the V.32 automode handshake in the originate mode. The range of S97 values is 15 to 70, representing 1.5 to 7.0 seconds. The default value of 30 (3.0 seconds) provides the timing necessary to connect to most V.22bis compatible modems. When compatibility with V.32 "late connecting modems" is a primary requirement, S97 should be set to 15. This value is also compatible with the timing specified in CCITT recommendation V.22bis. ***************************************************************************** 1.4 Additional Command Set Definitions The following items are critical parts of the AT Command Set, although they are not "commands." The AT prefix, the escape sequence, end-of-line character, and repeat last command function round out the elements of the command set. AT -- Command Prefix Modem commands begin with an AT prefix that gets the modem's attention. The speed and character format at which the DTE sends this prefix tells the modem the speed and format for responding to commands, and at which speed to attempt the connection. See the Installation Guide for the speeds, formats, and transmission methods supported by your modem. +++ -- Escape Sequence The escape sequence is used to take the modem from the on-li