RS422/485
Application Note
Table of Contents

Table of Contents
1 - Overview
2 - System Configuration
3 - Selecting Cabling
4 - Transient Protection
5 - Software
6 - Selecting Devices
7 - Further Information
Appendix A - EIA Specs
Appendix B - RS423 Standard

Chapter 1: Overview

   Introduction
   Data Transmission Signals
      Unbalanced Line Drivers
      Balanced Line Drivers
      Balanced Line Receivers
   EIA Standard RS-422 Data Transmission
   EIA Standard RS-485 Data Transmission
   Tristate Control of an RS-485 Device Using RTS
   Send Data Control of an RS-485 Device

Chapter 2: System Configuration

   Network Topologies
   Two Wire or Four Wire Systems
   Termination
   Biasing and RS-485 Network
   Extending the Specification

Chapter 3: Selecting RS-422 and RS-485 Cabling

   Number of Conductors
   Shielding
   Cable Characteristics

Chapter 4: Transient Protection of RS-422 and RS-484 Systems

   What Does a Surge Look Like?
      Surge Specifications
      Common Mode vs. Differential Mode
   Ground is not equal to Ground
   Transient Protection Using Isolation
      Isolation Theory
      Isolation Devices
   Transient Protection Using Shunting
      Shunting Theory
      Connecting Signal Grounds
      Shunting Devices
   Combining Isolation and Shunting
   Special Consideration for Fault Conditions
   Choosing the Right Protection For Your System

Chapter 5: Software

   Introduction
   RS-422 Systems
   RS-485 Driver Control
   RS-485 Receiver Control
   Master-Slave Systems
      Four Wire Master-Slave Systems
      Two Wire Master-Slave Systems
   Multi-Master RS-485 Systems
   Systems with Port Powered Converters

Chapter 6: Selecting RS-485 Devices

Chapter 7: Sources of Further Information

Appendix A: EIA Specification Summary

Appendix B: EIA Standard RS-423 Data Transmission