TECHNICAL REFERENCE
FOR HAYES MODEMS

15 Sept 1992
Version P2.0

CONTENTS

Introduction
Chapter 1: The Hayes Standard AT Command Set
Chapter 2: X.25 Communications
Appendix A: Communications Options
Appendix B: Troubleshooting Tips
Appendix C: Modem-to-DTE Interface
Appendix D: Application Suggestions
 

INTRODUCTION

This Technical Reference for Hayes Modem Users offers additional information about Hayes modems and 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 in the user documentation that accompanied your modem. All of the commands are described in this document.

You will 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 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.

How This Reference is Organized

This Reference is organized as follows:

Chapter 1:  The Hayes Standard AT Command Set
Provides definitions of the Hayes Standard AT Command Set including the commands, result codes, and S-registers.

Chapter 2:  X.25 Communications
Includes definitions of the commands used for X.25 packet-switched communications, PAD and National Parameters, and command 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 AT commands.

CHAPTER 1 
THE HAYES STANDARD AT COMMAND SET

This chapter is divided into three sections: "AT Commands Listing," "Result Code Listing," and "S-register Listing." The first section defines individual AT commands. Commands are listed 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 S-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 use of the Hayes Standard AT Command Set are also included.

Note: For the factory setting and available options/ranges for commands and registers, refer to the user documentation provided with your modem. Unless a command, register, or result code is listed in the user documentation, it is not supported by your modem, although it appears in this document.

Please select one of the following:

Chapter 2:  X.25 Communications

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Appendix A:  Communication Options

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Appendix B:  Troubleshooting Tips

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Appendix C:  Modem-to-DTE Interface

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Appendix D:  Modem Application Development

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