RS422/485 Application Note
RS422/485 Application Note
Table of Contents
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