RS-485 판매점 - RS-422 / RS-485

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Table of Contents

CHAPTER 1: OVERVIEW ........................................................................... 1

INTRODUCTION............................................................................................. 1

DATA TRANSMISSION SIGNALS ...................................................................... 1

Unbalanced Line Drivers ......................................................................... 1

Balanced Line Drivers ............................................................................. 1

Balanced Line Receivers.......................................................................... 3

EIA STANDARD RS-422 DATA TRANSMISSION .............................................. 3

EIA STANDARD RS-485 DATA TRANSMISSION .............................................. 6

TRISTATE CONTROL OF AN RS-485 DEVICE USING RTS.................................. 9

SEND DATA CONTROL OF AN RS-485 DEVICE .............................................. 11

CHAPTER 2: SYSTEM CONFIGURATION ............................................ 13

NETWORK TOPOLOGIES............................................................................... 13

TWO WIRE OR FOUR WIRE SYSTEMS............................................................ 13

TERMINATION............................................................................................. 16

BIASING AN RS-485 NETWORK.................................................................... 17

EXTENDING THE SPECIFICATION .................................................................. 19

CHAPTER 3: SELECTING RS-422 AND RS-485 CABLING .................. 20

NUMBER OF CONDUCTORS .......................................................................... 20

SHIELDING ................................................................................................. 20

CABLE CHARACTERISTICS ........................................................................... 20

CHAPTER 4: TRANSIENT PROTECTION OF RS-422 AND RS-485

SYSTEMS.................................................................................................... 23

WHAT DOES A SURGE LOOK LIKE? ................................................................ 23

Surge Specifications............................................................................... 23

Common Mode vs. Differential Mode..................................................... 25

GROUND ≠ GROUND.................................................................................... 26

TRANSIENT PROTECTION USING ISOLATION .................................................. 27

Isolation Theory..................................................................................... 27

Isolation Devices ................................................................................... 28

TRANSIENT PROTECTION USING SHUNTING .................................................. 28

Shunting Theory..................................................................................... 28

Connecting Signal Grounds ................................................................... 29

Shunting Devices ................................................................................... 29

COMBINING ISOLATION AND SHUNTING ....................................................... 29

SPECIAL CONSIDERATION FOR FAULT CONDITIONS....................................... 31

CHOOSING THE RIGHT PROTECTION FOR YOUR SYSTEM ................................. 31

RS-422/485 Application Note

Table of Contents

B&B Electronics -- PO Box 1040 -- Ottawa, IL 61350

PH (815) 433-5100 -- FAX (815) 434-7094

RS-485 반도체 회로 부품 판매점