Simrad EK80 - Page 138

136
394149/C
RS-422providesamechanismfortransmittingdataupto10Mbits/s.Thisinterfaceformat
usesabalancedsignalontwowires.Thisincreasesboththemaximumbaudrateandthe
physicallengthofthecable,anditreducesthenoise.Withahighqualitycable,youcan
useRS-422ondistancesupto1500meterseveninnoisyenvironments.RS-422isalso
speciedformulti-dropapplications.Thismeansthatonetransmittercansenddatato
upto10receivers.
Note
TherearenocommonstandardforRS-422pinconguration.Anymanufacturermay
choosetheirownconnectorpinsforthevarioussignalsused.InordertomaketheRS-422
connectiontoyourperipheraldeviceworkproperly,youmustalwaysconsulttherelevant
instructionsprovidedbythedevicemanufacturer.
ForemoreinformationabouttheRS-422serialcommunicationstandard,see(forexample):
•https://en.wikipedia.org/wiki/RS-422
RS-485serialcommunication
RS-485(alsoknownasTIA-485–A)isastandarddeningtheelectricalcharacteristics
ofdriversandreceiversforuseinbalanceddigitalmultipointsystems.Thestandardis
publishedbytheTelecommunicationsIndustryAssociation/ElectronicIndustriesAlliance
(TIA/EIA).DigitalcommunicationsnetworksimplementingtheRS-485standardcanbe
usedeffectivelyoverlongdistancesandinelectricallynoisyenvironments.Multiple
receiversmaybeconnectedtosuchanetworkinalinear,multi-dropconguration.
RS-485offersdatatransmissionspeedsof35Mbit/supto10mand100kbit/sat1200
m.Sinceitusesadifferentialbalancedlineovertwistedpair(likeRS-422),itcanspan
relativelylargedistances(typicallyupmaximum1200m).IncontrasttoRS-422,which
hasasingledrivercircuitwhichcannotbeswitchedoff,RS-485driversneedtobeput
intransmitmodeexplicitlybyassertingasignaltothedriver.ThisallowsRS-485to
implementlinearbustopologiesusingonlytwowires.Theequipmentlocatedalongasetof
RS-485wiresareinterchangeablycallednodes,stationsordevices.
RS-485,likeRS-422,canbemadefull-duplexbyusingfourwires.SinceRS-485isa
multi-pointspecication,however,thisisnotnecessaryinmanycases.
Note
TherearenocommonstandardforRS-485pinconguration.Anymanufacturermay
choosetheirownconnectorpinsforthevarioussignalsused.InordertomaketheRS-485
connectiontoyourperipheraldeviceworkproperly,youmustalwaysconsulttherelevant
instructionsprovidedbythedevicemanufacturer.
SimradEK80