Simrad EK15 - About the NMEA Telegram Format; National Marine Electronics Association (NMEA); NMEA Telegram Principles

SimradEK15
AbouttheNMEAtelegramformat
TheSimradEK15cansendandreceiveinformationtoandfromseveraldifferent
peripherals.Alltransmissionstakeplaceastelegramswithdatasentences.Each
telegramhasadenedformatandlength.
TheNMEA0183standardisthemostcommonprotocolusedtoreceiveandtransmitdata
toandfromperipheralsensors.AparametricsentencestructureisusedforallNMEA
data.Thesentencestartwitha“$”delimiter,andrepresentthemajorityofapproved
sentencesdenedbythestandard.Thissentencestructure,withdelimitedanddened
datales,isthepreferredmethodforconveyinginformation.
FormoreinformationabouttheNMEAstandard,theformatandthedatasentences,refer
totheirofcialpublications.TheirdocumentNMEA1083-Standardforinterfacing
marineelectronicdevicesexplainstheformatsindetail.Thedocumentcanbeobtained
fromhttp://www.nmea.org
.
Topics
•NationalMarineElectronicsAssociation(NMEA)onpage248
•NMEAtelegramprinciplesonpage248
•StandardNMEA0183communicationparametersonpage249
•NMEAsentencestructureonpage249
NationalMarineElectronicsAssociation(NMEA)
TheNationalMarineElectronicsAssociation(NMEA)hasdenedcommunication
standardsformaritimeelectronicequipment,andtheEK15echosounderconformsto
thesestandards.ThemostcommonstandardisNMEA0183,andtheNationalMarine
ElectronicsAssociationdescribesitasfollows:
TheNMEA0183InterfaceStandarddeneselectricalsignalrequirements,data
transmissionprotocolandtime,andspecicsentenceformatsfora4800baudserial
databus.Eachbusmayhaveonlyonetalkerbutmanylisteners.
—NationalMarineElectronicsAssociation
FormoreinformationabouttheNationalMarineElectronicsAssociationandtheNMEA
0183standard,refertotheorganization'swebsiteathttp://www.nmea.org
.
NMEAtelegramprinciples
Tomoveinformationbetweentwoelectronicunits,thedataarecollectedintelegrams.
Thecontent(protocol)ofeachtelegramisdenedbytheNMEAstandard,andseveral
telegramtypesexisttoallowdifferenttypeofdatatobedistributed.
Thephrasedatagramisalsofrequentlyusedaboutthiscommunicationmethod.
Unlessyouwishtowriteyourownsoftware,youdonotneedtoknowhowthese
telegramsaredesigned.However,wheneveryousetupequipmentinterfaces,youneed
toensurethateachsystemonyourcommunicationlineissetuptosendandreceivethe
sametelegram.Thestandardallowsonesystemtosenddata(a“talker")andseveral
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