Inside Macintosh: Devices /

Chapter 7 - Serial Driver

This chapter describes how you can use the Serial Driver to transfer data to a device connected to a Macintosh modem or printer port. The Serial Driver supports asynchronous serial data communication between applications and serial devices through these ports.

The Serial Driver provides low-level support for communicating with serial devices that cannot be accessed through the Communications Toolbox or Printing Manager. For example, a scientific instrument or a printer that does not support QuickDraw. Before you decide to use the Serial Driver, you should determine whether it is the appropriate solution for your communication needs.

The Communications Toolbox is the recommended method for integrating modems and other telecommunications devices into the Macintosh environment. The Communications Toolbox provides hardware-independent services and a standard interface that offers compatibility with all Macintosh models. To find out more about the Communications Toolbox, see Inside the Macintosh Communications Toolbox.

Likewise, the Printing Manager is the recommended interface for printers and similar output devices. Using the Printing Manager makes your hardware or software product compatible with every other device or application that supports this standard interface. Refer to Inside Macintosh: Imaging With QuickDraw for more information.

To use the Serial Driver, you should understand how to open, close, and communicate with device drivers using the Device Manager. You can find this information in the chapter "Device Manager" in this book. For information about the Macintosh serial port hardware, including circuit diagrams and signal descriptions, see Guide to the Macintosh Family Hardware, second edition.

This chapter begins with a brief summary of key concepts in serial data communication, then describes how you can use the Serial Driver to

• configure a Macintosh serial port
• specify a data transfer buffer
• send and receive data through a serial port
• interpret serial communication errors

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Chapter Contents

Introduction to Serial Communication

Asynchronous and Synchronous Communication

Duplex Communication

Flow Control Methods

Asynchronous Serial Communication Protocol

The RS-422 Serial Interface

About the Serial Driver

Macintosh Serial Architecture

Serial Communication Errors

Using the Serial Driver

Opening the Serial Driver

Specifying an Alternate Input Buffer

Setting the Handshaking Options

Setting the Baud Rate and Data Format

Reading and Writing to the Serial Ports

Synchronous I/O Requests

Asynchronous I/O Requests

Closing the Serial Driver

Synchronous Clocking

Serial Driver Reference

Serial Driver Routines

Low-Level Routines

Serial Driver Version [status code 9]

Set Baud Rate [control code 13]

Set Handshaking Options [control code 14]

Set Miscellaneous Options [control code 16]

Assert DTR [control code 17]

Negate DTR [control code 18]

Simple Parity Error Replacement [control code 19]

Extended Parity Error Replacement [control code 20]

Set XOFF State [control code 21]

Clear XOFF State [control code 22]

Send XON Conditional [control code 23]

Send XON Unconditional [control code 24]

Send XOFF Conditional [control code 25]

Send XOFF Unconditional [control code 26]

Serial Hardware Reset [control code 27]

Summary of the Serial Driver

Pascal Summary

Constants

Data Types

Routines

C Summary

Constants

Data Types

Functions

Assembly-Language Summary

Data Structures

Device Manager Interface

Result Codes