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Serial HOWTO

David S.Lawyer `dave@lafn.org` original by Greg Hankins

v2.25 January 2007

This document describes the UART serial port features other than those which should be covered by Modem-HOWTO, PPP-HOWTO, Serial-Programming-HOWTO, or Text-Terminal-HOWTO. It lists info on multiport serial cards. It contains technical info abobout the serial port itself in more detail than found in the above HOWTOs and should be best for troubleshooting when the problem is the serial port itself. If you are dealing with a Modem, PPP (used for Internet access on a phone line), or a Text-Terminal, those HOWTOs should be consulted first.

1. Introduction

5. Is the Serial Port Obsolete?

5.1 Introduction
5.2 EIA-232 (RS-232) Cable Is Low Speed & Short Distance
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        19.5 UART Model Numbers
        
        20. Pinout and Signals
        
        20.1 Pinout of 9-pin and 25-pin serial connectors
        20.2 Signals May Have No Fixed Meaning
        20.3 Cabling Between Serial Ports
        20.4 RTS/CTS and DTR/DSR Flow Control
        20.5 Preventing a Port From Opening
        
        21. Voltage Waveshapes
        
        21.1 Voltage for a Bit
        21.2 Voltage Sequence for a Byte
        21.3 Parity Explained
        21.4 Forming a Byte (Framing)
        21.5 How "Asynchronous" is Synchronized
        
        22. Other Serial Devices (not async EIA-232)
        
        22.1 Successors to EIA-232
        22.2 EIA-422-A (balanced) and EIA-423-A (unbalanced)
        22.3 EIA-485
        22.4 EIA-530
        22.5 EIA-612/613
        22.6 The Universal Serial Bus (USB)
        22.7 Firewire
        22.8 MIDI
        22.9 Synchronization & Synchronous
        
        23. Other Sources of Information
        
        23.1 Books
        23.2 Serial Software
        23.3 Related Linux Documents
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        ml">Voltage Waveshapes-1.htmlNext Previous Contents

Serial HOWTO

David S.Lawyer dave@lafn.org original by Greg Hankins

1. Introduction

5. Is the Serial Port Obsolete?

20. Pinout and Signals

21. Voltage Waveshapes

22. Other Serial Devices (not async EIA-232)

23. Other Sources of Information

David S.Lawyer `dave@lafn.org` original by Greg Hankins