485应用指南 485通讯原理及应用指南new

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1、RS-422andRS-485ApplicationNoteInternationalHeadquartersB&BElectronicsMfg.Co.Inc.707DaytonRoad--P.O.Box1040--Ottawa,IL61350USAPhone(815)433-5100--GeneralFax(815)433-5105HomePage:www.bb-elec.comCustomerServicee-mail:sales@bb-elec.com--Fax(815)433-5109TechnicalSupporte-mail:support@bb.elec.com--

2、Fax(815)433-5104EuropeanHeadquartersB&BElectronicsLtd.WestlinkCommercialPark,Oranmore,Co.Galway,IrelandPhone(353)91792444--Fax(353)91792445HomePage:www.bb-europe.comSalese-mail:sales@bb-europe.comTechnicalSupporte-mail:support@bb-europe.comÓCopyrightB&BElectronics--RevisedOctober1997RS-422/48

3、5ApplicationNoteCoverPage©CopyrightB&BElectronics--RevisedOctober1997B&BElectronicsMfgCo–707DaytonRd-POBox1040-OttawaIL61350-Ph815-433-5100-Fax815-433-5104B&BElectronicsLtd–WestlinkComm.Pk–Oranmore,Galway,Ireland–Ph353-91-792444–Fax353-91-792445TableofContentsCHAPTER1:OVERVIEW................

4、................................................................1INTRODUCTION..................................................................................................1DATATRANSMISSIONSIGNALS..........................................................................1UnbalancedLineDrive

5、rs.............................................................................1BalancedLineDrivers..................................................................................1BalancedLineReceivers..............................................................................3EIASTANDARD

6、RS-422DATATRANSMISSION.................................................3EIASTANDARDRS-485DATATRANSMISSION.................................................6TRISTATECONTROLOFANRS-485DEVICEUSINGRTS....................................9SENDDATACONTROLOFANRS-485DEVICE...............................

7、..................11CHAPTER2:SYSTEMCONFIGURATION...............................................13NETWORKTOPOLOGIES...................................................................................13TWOWIREORFOURWIRESYSTEMS...................