Raymarine A65 - System Protocols

3.8Systemprotocols
YourMultifunctionDisplaycanconnecttovariousinstrumentsand
displaystoshareinformationandsoimprovethefunctionalityof
thesystem.Theseconnectionsmaybemadeusinganumberof
differentprotocols.Fastandaccuratedatacollectionandtransferis
achievedbyusingacombinationofthefollowingdataprotocols:
•SeaTalk
hs
•SeaTalk
ng
•NMEA2000
•SeaTalk
•NMEA0183
Note:Youmayndthatyoursystemdoesnotuseallofthe
connectiontypesorinstrumentationdescribedinthissection.
SeaTalk
hs
SeaTalk
hs
isanethernetbasedmarinenetwork.Thishighspeed
protocolallowscompatibleequipmenttocommunicaterapidlyand
sharelargeamountsofdata.
InformationsharedusingtheSeaT alk
hs
networkincludes:
•Sharedcartography(betweencompatibledisplays).
•Digitalradardata.
•Sonardata.
Seatalk
ng
SeaTalk
ng
(NextGeneration)isanenhancedprotocolforconnection
ofcompatiblemarineinstrumentsandequipment.Itreplacesthe
olderSeaT alkandSeaTalk
2
protocols.
SeaTalk
ng
utilizesasinglebackbonetowhichcompatible
instrumentsconnectusingaspur.Dataandpowerarecarriedwithin
thebackbone.Devicesthathavealowdrawcanbepoweredfrom
thenetwork,althoughhighcurrentequipmentwillneedtohavea
separatepowerconnection.
SeaTalk
ng
isaproprietaryextensiontoNMEA2000andtheproven
CANbustechnology.CompatibleNMEA2000andSeaTalk/
SeaTalk
2
devicescanalsobeconnectedusingtheappropriate
interfacesoradaptorcablesasrequired.
NMEA2000
NMEA2000offerssignicantimprovementsoverNMEA0183,most
notablyinspeedandconnectivity.Upto50unitscansimultaneously
transmitandreceiveonasinglephysicalbusatanyonetime,
witheachnodebeingphysicallyaddressable.Thestandard
wasspecicallyintendedtoallowforawholenetworkofmarine
electronicsfromanymanufacturertocommunicateonacommon
busviastandardizedmessagetypesandformats.
SeaTalk
SeaTalkisaprotocolwhichenablescompatibleinstrumentsto
connecttoeachotherandsharedata.
TheSeaT alkcablesystemisusedtoconnectcompatible
instrumentsandequipment.Thecablecarriespoweranddataand
enablesconnectionwithouttheneedforacentralprocessor.
AdditionalinstrumentsandfunctionscanbeaddedtoaSeaTalk
system,simplybypluggingthemintothenetwork.SeaTalk
equipmentcanalsocommunicatewithothernon-SeaTalkequipment
viatheNMEA0183standard,providedasuitableinterfaceisused.
NMEA0183
TheNMEA0183DataInterfaceStandardwasdevelopedby
theNationalMarineElectronicsAssociationofAmerica.Itisan
internationalstandardtoenableequipmentfrommanydifferent
manufacturerstobeconnectedtogetherandshareinformation.
TheNMEA0183standardcarriessimilarinformationtoSeaT alk.
Howeverithastheimportantdifferencethatonecablewillonly
carryinformationinonedirection.ForthisreasonNMEA0183is
generallyusedtoconnectadatareceiverandatransmittertogether,
e.g.acompasssensortransmittingheadingtoaradardisplay.This
informationispassedin‘sentences’,eachofwhichhasathree
lettersentenceidentier.Itisthereforeimportantwhenchecking
compatibilitybetweenitemsthatthesamesentenceidentiersare
usedsomeexamplesofwhichare:
•VTG-carriesCourseandSpeedOverGrounddata.
•GLL-carrieslatitudeandlongitude.
•DBT-carrieswaterdepth.
•MWV-carriesrelativewindangleandwindspeeddata.
NMEABaudrates
TheNMEA0183standardoperatesatanumberofdifferent
speeds,dependingupontheparticularrequirementorequipment
capabilities.Typicalexamplesare:
•4800baudrate.Usedforgeneralpurposecommunications,
includingFastHeadingdata.
•38400baudrate.UsedforAISandotherhighspeedapplications.
32NewaSeries/NewcSeries/NeweSeries