Installation manual
SimradPI50
AbouttheNMEAtelegramformat
TheSimradPI50cansendandreceiveinformationtoandfromseveraldifferent
peripherals.Alltransmissionstakeplaceastelegramswithdatasentences.Each
telegramhasadenedformatandlength.
TheNMEA0183standardisthemostcommonprotocolusedtoreceiveandtransmitdata
toandfromperipheralsensors.AparametricsentencestructureisusedforallNMEA
data.Thesentencestartwitha“$”delimiter,andrepresentthemajorityofapproved
sentencesdenedbythestandard.Thissentencestructure,withdelimitedanddened
datales,isthepreferredmethodforconveyinginformation.
FormoreinformationabouttheNMEAstandard,theformatandthedatasentences,refer
totheirofcialpublications.TheirdocumentNMEA1083-Standardforinterfacing
marineelectronicdevicesexplainstheformatsindetail.Thedocumentcanbeobtained
fromh
t t p : / / w w w . n m e a . o r g .
Topics
•AboutNMEAonpage104
•Telegramsonpage104
•StandardNMEA0183communicationparametersonpage105
•Sentencestructureonpage105
AboutNMEA
TheNationalMarineElectronicsAssociation(NMEA)hasdenedcommunication
standardsformaritimeelectronicequipment,andthePI50echosounderconformsto
thesestandards.ThemostcommonstandardisNMEA0183,andtheNationalMarine
ElectronicsAssociationdescribesitasfollows:
TheNMEA0183InterfaceStandarddeneselectricalsignalrequirements,data
transmissionprotocolandtime,andspecicsentenceformatsfora4800baudserial
databus.Eachbusmayhaveonlyonetalkerbutmanylisteners.
—NationalMarineElectronicsAssociation
FormoreinformationabouttheNationalMarineElectronicsAssociationandtheNMEA
0183standard,refertotheorganization’swebsiteath
t t p : / / w w w . n m e a . o r g .
Telegrams
Tomoveinformationbetweentwoelectronicunits,thedataarecollectedintelegrams.
Thecontent(protocol)ofeachtelegramisdenedbytheNMEAstandard,andseveral
telegramtypesexisttoallowdifferenttypeofdatatobedistributed.
Thephrasedatagramisalsofrequentlyusedaboutthiscommunicationmethod.
Unlessyouwishtowriteyourownsoftware,youdonotneedtoknowhowthese
telegramsaredesigned.However,wheneveryousetupequipmentinterfaces,youneed
toensurethateachsystemonyourcommunicationlineissetuptosendandreceivethe
sametelegram.Thestandardallowsonesystemtosenddata(a“talker")andseveral
104
328459/B