Raymarine c95 - System Protocols

3.8Systemprotocols
YourMultifunctionDisplaycanconnecttovariousinstruments
anddisplaystoshareinformationandsoimprovethe
functionalityofthesystem.Theseconnectionsmaybemade
usinganumberofdifferentprotocols.Fastandaccuratedata
collectionandtransferisachievedbyusingacombinationofthe
followingdataprotocols:
•SeaT alk
hs
•SeaT alk
ng
•NMEA2000
•SeaT alk
•NMEA0183
Note:Youmayndthatyoursystemdoesnotuseallofthe
connectiontypesorinstrumentationdescribedinthissection.
SeaTalk
hs
SeaTalk
hs
isanethernetbasedmarinenetwork.Thishighspeed
protocolallowscompatibleequipmenttocommunicaterapidly
andsharelargeamountsofdata.
InformationsharedusingtheSeaTalk
hs
networkincludes:
•Sharedcartography(betweencompatibledisplays).
•Digitalradardata.
•Sonardata.
Seatalk
ng
SeaTalk
ng
(NextGeneration)isanenhancedprotocolfor
connectionofcompatiblemarineinstrumentsandequipment.It
replacestheolderSeaT alkandSeaT alk
2
protocols.
SeaTalk
ng
utilizesasinglebackbonetowhichcompatible
instrumentsconnectusingaspur.Dataandpowerarecarried
withinthebackbone.Devicesthathavealowdrawcanbe
poweredfromthenetwork,althoughhighcurrentequipmentwill
needtohaveaseparatepowerconnection.
SeaTalk
ng
isaproprietaryextensiontoNMEA2000andthe
provenCANbustechnology.CompatibleNMEA2000and
SeaTalk/SeaTalk
2
devicescanalsobeconnectedusingthe
appropriateinterfacesoradaptorcablesasrequired.
NMEA2000
NMEA2000offerssignicantimprovementsoverNMEA0183,
mostnotablyinspeedandconnectivity.Upto50unitscan
simultaneouslytransmitandreceiveonasinglephysicalbusat
anyonetime,witheachnodebeingphysicallyaddressable.The
standardwasspecicallyintendedtoallowforawholenetwork
ofmarineelectronicsfromanymanufacturertocommunicateon
acommonbusviastandardizedmessagetypesandformats.
SeaTalk
SeaTalkisaprotocolwhichenablescompatibleinstrumentsto
connecttoeachotherandsharedata.
TheSeaTalkcablesystemisusedtoconnectcompatible
instrumentsandequipment.Thecablecarriespoweranddata
andenablesconnectionwithouttheneedforacentralprocessor.
AdditionalinstrumentsandfunctionscanbeaddedtoaSeaT alk
system,simplybypluggingthemintothenetwork.SeaT alk
equipmentcanalsocommunicatewithothernon-SeaTalk
equipmentviatheNMEA0183standard,providedasuitable
interfaceisused.
NMEA0183
TheNMEA0183DataInterfaceStandardwasdevelopedby
theNationalMarineElectronicsAssociationofAmerica.Itisan
internationalstandardtoenableequipmentfrommanydifferent
manufacturerstobeconnectedtogetherandshareinformation.
TheNMEA0183standardcarriessimilarinformationtoSeaT alk.
Howeverithastheimportantdifferencethatonecablewillonly
carryinformationinonedirection.ForthisreasonNMEA0183
isgenerallyusedtoconnectadatareceiverandatransmitter
together,e.g.acompasssensortransmittingheadingtoaradar
display.Thisinformationispassedin‘sentences’,eachofwhich
hasathreelettersentenceidentier.Itisthereforeimportant
whencheckingcompatibilitybetweenitemsthatthesame
sentenceidentiersareusedsomeexamplesofwhichare:
•VTG-carriesCourseandSpeedOverGrounddata.
•GLL-carrieslatitudeandlongitude.
•DBT-carrieswaterdepth.
•MWV-carriesrelativewindangleandwindspeeddata.
NMEABaudrates
TheNMEA0183standardoperatesatanumberofdifferent
speeds,dependingupontheparticularrequirementorequipment
capabilities.Typicalexamplesare:
•4800baudrate.Usedforgeneralpurposecommunications,
includingFastHeadingdata.
•38400baudrate.UsedforAISandotherhighspeed
applications.
32NewaSeries/NewcSeries/NeweSeries