458
442703/B
AboutNMEAandstandarddatagramformats
Topics
NMEA,page458
AbouttheNMEAdatagramformats,page458
NMEAsentencestructure,page459
StandardNMEA0183communicationparameters,page460
NMEA
TheNationalMarineElectronicsAssociation(NMEA)hasdenedcommunication
standardsformaritimeelectronicequipment.TheST90Fishndingsonarsupportsthese
standardsforcommunicationwithexternalsensorsandperipheralsystems.
ThemostcommonstandardisNMEA0183.TheNationalMarineElectronics
Associationdescribesitasfollows:
TheNMEA0183InterfaceStandarddeneselectricalsignalrequirements,data
transmissionprotocolandtime,andspecicsentenceformatsfora4800-baudserial
databus.Eachbuscanhaveonlyonetalkerbutmanylisteners.
NationalMarineElectronicsAssociation
FormoreinformationabouttheNationalMarineElectronicsAssociationandtheNMEA
0183standard,refertotheorganization'swebsiteat:
•http://www.nmea.org
AbouttheNMEAdatagramformats
TheST90cansendandreceiveinformationtoandfromseveraldifferentperipherals.
Alltransmissionstakeplaceasdatagramswithdatasentences.Eachdatagramhasa
denedformatandlength.
TheNMEA0183standardisthemostcommonprotocolusedtoreceiveandtransmit
datatoandfromperipheralsensors.Aparametricsentencestructureisusedforall
NMEAdata.
Thesentencestartswitha“$”delimiterandrepresentsthemajorityofapproved
sentencesdenedbythestandard.Thissentencestructurewithdelimitedanddened
datales,isthepreferredmethodforconveyinginformation.
FormoreinformationabouttheNMEAstandard,theformatandthedatasentences,refer
toNMEA’sofcialpublications.TheNMEA1083-StandardforInterfacingMarine
ElectronicDevicesdocumentexplainstheformatsindetail.Thedocumentcanbe
obtainedfromNMEA.
SimradST90InstallationManual