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Your complete guide to building an NMEA 2000® network
ContentsWho are the NMEA and What is NMEA 2000? 33 Who are the NMEA?3 What is NMEA 2000?3 The Network That CAN3 DeviceNet3 Certification
Minimum Network Requirements and Network Limitations 44 MinimumNetworkRequirements4 CommonPhrases
NMEA 2000 Network Limitations 5
Actisense Starter Kits 66 TheoriginalActisensestarterKit6 RIBStarterKit6 SmallBoatNetwork
Powering and fusing the network 77 PowerT-Piece7 MicroPowerCable7 SmallBoatNetwork8 QuickNetworkBlock
T-Pieces and Termination Resistors 99 MicroT-Pieces9 Micro4-WayT-Pieces
Connecting Devices and Extending the backbone 1010 TrunkandDropCable10 BulkCable
Field Fit Connectors 1111 FieldFitConnectors
5 Steps to Field Fit Installation Success 12
The Quick Network Block 1313 AtaGlance14 DetailedOverview14 RaymarineSeaTalkNGSolution Network Diagnosis 1414 Glandedoption15 AdequatePowerSupply&TerminationResistance16 DiggingDeeper17 Checkingavailibilityandaccuracyofdataonthenetwork
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Who are the NMEA and What is NMEA 2000?
Who are the NMEA?TheNMEAstandsforNationalMarineElectronicsAssociation.Inanutshell,they’reanotforprofitorganisationwhosemissionistoimprovedatacommunicationsbetweenmarineelectronicsmanufacturers.Readmoreatwww.nmea.org
What is NMEA 2000?NMEA2000isanopenstandarddesignedbytheNMEAtohelpthemachievetheirmissionbystandardisingthemessagesandconnectorsystemusedfordevicesinthemarineindustry.Thereisacommonmisconceptionthattheterm‘openstandard’meansfreelyavailablewheninfactitmeansthatthestandardisavailabletobuyatareasonablecostfromtheirwebsite.ItisimportanttorememberthattheNMEAisnotforprofit(NFP)andthestandardscreateanimportantsourceofincomesothattheycancontinuetoexist.
The Network That CANNMEA2000isbasedonasystemknownasCANwhichstandsfor‘ControllerAreaNetwork’.OneofthereasonstheNMEAchosethissystemoversomethinglikeEthernet(forexample)whichhasamuchwiderbandwidth,andcansupportRADARandvideo,isbecauseCANhastheabilitytoguaranteemessagedeliveryevenwhenthenetworkis100%loaded.AnimportantfeaturewhenyouconsiderthatthenetworkislikelytocontainimportantGPSinformation.
DeviceNetTheNMEAadopted the ‘DeviceNet’ standard for thehardware (cablesandconnectors) that is used to createanNMEA2000network. TheDeviceNetstandardwasalready inuseby theautomotiveandagricultural industries (tonamea few)so it isaprovenrobustsystemandcanwithstandtheharshconditionsofthemarineenvironment.
CertificationThere isacertificationprocess inplace forNMEA2000. Thishelpstheuser tounderstandthat ifadevicecarriestheNMEA2000logotheycanrestassuredthatitiscompatiblewithanNMEA2000networkandanyother‘NMEA2000Certified’device. Somecommonterms for theuser tobeawareofare ‘CANbusapproved’or ‘NMEA2000Compatible’astheseareunlikelytohavegonethroughtheNMEA2000certificationprocess.
‘NMEA2000Approved’isatermusedforcablesandconnectorsthatmeettherequirementsforNMEA2000astheydonotrequirethesamecertificationprocess.
http://www.nmea.orghttp://www.nmea.org/
12v
Minimum Network Requirements and Network Limitations
Minimum Network RequirementsThefollowingaretheessentialcomponentsofanyNMEA2000network:• Powerinsertionpoint-fused.• 2xNMEA2000certifieddevices(atleast1xTXand1xRX)andameanstoconnectthemtothenetwork.ThiscanbeviaT-piecesorotherproductswhichwillbediscussedlater.• Terminationresistors-Precisely2,nomore,noless.
Common PhrasesYouwillhearsomecommonphrasesusedwhendiscussingNMEA2000networks.Here’swhattheymean:Backbone:Themaintrunkofcablethatrunsthroughtheboattoformthenetwork.T-piecesareconnectedalongthenetworkfordevicestopluginto.Instrumentdrop:ThelengthofcablethatconnectsanNMEA20000devicetothebackbonePGN:Standsfor‘ParameterGroupNumber’.ThemessagesusedbyNMEA2000devicesforsharinginformation.
ThediagrambelowillustrateshowanNMEA2000networkisputtogether:
Cable Type Max Length Max Amp Power Pair Data Pair
Per drop cable 6m
Sum of all drop cables 72m
Micro/Lite Backbone(Terminator to terminator) 100m 3 22 AWG 24 AWG
Mid backbone(Terminator to terminator) 250m 4 18 AWG 20 AWG
Mini/Heavy Backbone(Terminator to terminator) 250m 8 15 AWG 18 AWG
NMEA 2000 Network Limitations
Actisense Starter Kits
ActisensecanprovideyouwitheverythingyouneedtogetstartedwithanNMEA2000networkinavarietyofflavours.Here’sanoutlineoftheircontents.Eachindividualitemwillbediscussedinmoredetailinfutureepisodes,alongwithotheritemstocomplementyourNMEA2000network.
The original Actisense starter Kit• PowerT-piece-ContainsatwinpairofpowercablesforevenpowerdistributionacrosstheNMEA2000network.
• 2x T-pieces - for extending the network from the power T-piece and connectingNMEA 2000devicestothenetwork.
• 2xterminationresistors-Tomaintainsignalintegrity.• 1x2metrecable-forextendingthelengthofthebackboneifneededortoconnectanNMEA2000devicetoaT-piece.FittedwithovermouldedDeviceNetstandardconnectorstoprotectfromwateringress.
RIB Starter Kit• 1x4-wayT-piece-providinginstrumentdropsforupto3devices(oneportisusedforpower).• 1xMicropowercord-canbepluggedstraightintoanyavailableportonthe4-wayT-piecetoprovidenetworkpower.• 2xTerminationresistors-Tomaintainsignalintegrity.• Networkcanbeextendedbytemporarilyremovingaterminationresistor,plugginginadditionalT-piecesandreplacingtheterminationresistorattheendofthebackbone.
Small Boat Network• Spacefor4xinstrumentdrops.• Overmouldedpowercordattached.• 2xTerminationresistorsbuiltin.
45132
+
45132
+_ S _
FemaleNET-HNET-LShieldNET-CNET-S
MaleNET-HNET-LShieldNET-CNET-S
Powering and fusing the network
Power T-PieceTheActisensepowerT-piecehasatwinpairofpowerwires,oneforeachsideoftheT-piece.Bothpairsmustbeconnectedtoa12/24Voltpowersupply(viafusepanel)sothattheelectricalloadcanbedistributedevenly.
Whenusing24Vsystems,awarningmustbeinstalledonthenetworktoensureanyoneinstallingnewdevicesisaware.ThisisbecausetheNMEA2000specificationdoesn’tofficiallysupport24Vbutthislevelofpowersupplycanbeusedifinstalleddevicesarecapableofsupportingit.AllActisensedevicessupport24Vpowersupplies.
TheillustrationbelowdetailstheinternalwiringoftheActisensepowerT-piece.Notethepairofpositiveandnegativepinsoneachside.
Micro Power CableThiscableisdesignedforsmallinstallationsthatwillbeusedwiththeRIBStarterKitsoitonlyhasasinglepairofpowerwires.TheMicroPowerCablehasaMicroDeviceNetconnectorsothatitcanbeeasilypluggedintothemostsuitableportonthe4-wayT-pieceprovided.
TheMicroPowerCableshouldneverbeusedonlargerinstallations.
Small Boat NetworkThepowercordfortheSmallBoatNetworkisovermouldedtothecaseofa4-wayT-piecetopreventwateringress.Powerisavailabletoall4portsoncethepairofbarewiresisconnectedtoa12Vor24Vpowersupply.
Quick Network BlockTheActisenseQuickNetworkBlock(QNB)providesaversatileandeasytoinstallsolutionforanyNMEA2000,largeorsmall.ThissectionillustrateshowtheQNBcanbeusedforprovidingpowertoyournetworkandtheaddedbenefitsofitsfeatures.Otherbenefitswillbeshownlaterinthisdocument.(See“TheQuickNetworkBlock”onpage13)
Note:TheQNBwillnotregulatethevoltagethatisbeingprovidedtothenetwork.
Power Insertion
Fuses
Fuse 1 status LED
Power LED
Polarity LED
Presence of data LED
Fuse 2 status LED
T-Pieces and Termination Resistors
Micro T-PiecesT-piecescanbeconnecteddirectlytothePowerToryoucanusealengthofNMEA2000approvedcablingtoextendthebackboneandjointheT-piecetotheendofthecable.Theinstrumentdropmustconnectedatrightanglestothebackbonesoitisclearwhatisthebackboneandwhatisaninstrumentdrop.
Micro 4-Way T-PiecesThe photos on the right illustrate the different T-piece options available fromActisense.Theyareshowninactualsize(ifthisPDFhasbeenprintedtoA4size)anddemonstratethespacesavingthatthe4-wayT-piececanprovide.
Termination ResistorsAteachendofthebackboneaterminationresistormustbeinstalled.Each termination resistor is 120Ohms and is connected in parallelacrossthedatapairofwireswhenpluggedintoNMEA2000approvedcables and connectors. Thisprovides a total of 60Ohms resitanceacrossthenetworkandisessentialtodataintegrity.
Connecting Devices and Extending the backbone
Trunk and Drop CableIfthelengthofcablerequiredbetweenT-pieces/devicesisknown,pre-assembledcablescanbeusedforextendingthebackboneorpluggingindevicestothenetwork.Thisoptionsavesalotoftimenothavingtocutthecableandwireaconnectortoityourself.ActisenseNMEA2000approvedcablingisavailableinthefollowingsizes:
• 0.25m• 0.5m• 1m• 2m• 3m• 4m• 5m• 6m(maximumlengththatcanbeusedforaninstrumentdropasdefinedbytheNMEA2000specification)• 8m• 10m
Bulk CableIfcustomisedlengthsofcableareneeded,orlengthsofcablegreaterthan10metres,bulkcableisavailablein100metrereels.ThiscanbeusedtogetherwithActisensefieldfitconnectors.
Field Fit Connectors
Field Fit ConnectorsWhenbulkcableisusedaconnectorwillneedtobewiredtotheendssothatthecablecanbepluggedintothenetworkoradevice.Followourfivestepstofieldfitinstallationsuccessonthenextpagethatillustratesthebestmethodforinstallingfieldfitconnectors,includingwhichcolourwiresconnecttowhichpins.TheNMEA2000wiringcoloursystemisstandardisedsothecoloursandpinnumberswillbethesameforanywireandconnectorcombinationthatusesthesameDeviceNetstandard.
Actisensefieldfitconnectorsareavailableasstraightorrightangledoptionsandinmaleandfemalevariantstosuitanyinstallationrequirement.
Note the plastic sleeve that coversthecentrepin. This is toprevent thebarewiresthatextrudefromtheother4pinsmakingcontactwiththecopperand creating a short. Not all field fitconnectorshavethisplasticsleeve.
5 Steps to Field Fit Installation Success
Backbone connectionsInstrument drops
Labels are the same for both sides and for both variants of QNB-1.
See the next page for more information on the different variants available.
Panelmountedwireconnectorsareavailableasastandaloneproductfor creating through bulkhead connections.They can also be used to replace theconnectorsintheQNBifneeded.
Blankingplugsarealsoavailable toprotectanyunusedpanelmountedwireconnectorsfromwatersplashes.
The Quick Network Block
At a GlanceThenextpageprovidesamoredetailedoverviewoftheQuickNetworkBlock.Pleasereferto“Poweringandfusingthenetwork”onpage7forfulldetailsofthepowerinsertionfeaturesoftheQuickNetworkBlock.
Wire Colour Connects to
Red NET-S
Black NET-C
White NET-H
Blue NET-L
Bare/green Shield
Detailed OverviewTheActisenseQuickNetworkBlock(QNB)providesasimple‘networkinabox’solution.Itcanbeusedinareasofhighinstrumentdensitywhendevicesareupto12metresapart fromeachother (6metredropfromdevicetoQNBperdevice). Anotherpopularuse for theQNBiswithengineersthathaveaneedtocreateasmallNMEA2000testenvironmentonaworkbench(forexample).
Raymarine SeaTalkNG SolutionAlessobviousbenefittotheQNBistheabilitytomixandmatchDeviceNetstandardconnectorswithRaymarineSeaTalkNG(STNG)connectors.AsSTNGusesexactlythesamedataasNMEA2000butchoosesnottousetheDeviceNetstandardforit’sconnectorsystem,adaptercablesareneededtochangetheconnectortypewheninstallingSTNGdevicesonNMEA2000networks,orviceversa.
STNGcablescanbestrippedbackandwireddirectlytotheterminalsinsideeithervariantoftheQNB-1,whichmeansthatyoucanmixandmatchSTNGwithDeviceNet.ThewiringcoloursinsideSTNGcablesarethesameasDeviceNetcables.
Removingtheconnectors fromthePMWvariant isnotadvisedastheQNB-1will lose itswatertight integrity. Instead,werecommendsimplyconnectinganSTNGbackbonecablethroughoneorbothofthebackboneglandstoenablethemix&matchingoptionsdescribedabove.
Glanded optionA glanded option of the QNB is available for more customisedinstallationsusingActisensebulkcable. Arubber,self-tighteningsealinsideeachglandclampsaroundthecablewhenitisinstalledandthescrewistightened.
Panel Mounted Wire connector option (PMW)The PMW option is the simplest to install as all the connectors arepre-wiredandprovideplug&playconnectivity.Thebackboneshouldalwaysbeinstalledthroughtheglandsprovidedthatarefurthestfromthepowerinsertionpoint.
NET-SNET-CNET-LNET-HSHIELD
Network Diagnosis
Nomatterhowrobustanetworkis,howsimpleitistoinstall,orhowwellithasbeendocumentedandmanagedtherewillinvariablybeissuesthatneedtacklingatsomepoint.ThisepisodewillhelptoidentifysomegoodplacestostartwhendiagnosinganNMEA2000network.
Adequate Power Supply & Termination Resistance• TestvoltageatentrypointEnsuringthenetworkisreceivingapowersupplyisalwaysthebestplacetostart.Assomedevicesmaybepoweredbythenetwork,knowingthatthesedevicesareworkingisaquickwinforthistest.Thepowerattheentrypointshouldnotexceed14Vfroma12Vsupply.
• TestvoltageatnetworkextremitiesWithnetworkdevicesusingupsomeofthesuppliedpowerandimpedancefromcablingalsodroppingthevoltage,itisimportanttoknowthatthevoltageattheendofeachbackbonelegisadequate.TemporarilyremoveaterminationresistorfromtheendofthenetworkanduseavoltmetertomeasureacrosstheNET-SandNET-Cpins.Themeasuredvalueshouldbeatleast9V.ThediagramsbelowwillhelpyoufindthesepinswhenusingActisenseconnectors.
AnActisensePanelMountedWire(PMW)connectorisagreattoolforpluggingintoaspareT-piecetoquicklyidentifythecorrectpinsviathewiringcolours.ItisrecommendedthateachwirefromthePMWisterminatedinsideaterminalblockpriortopluggingitintothenetworkasvoltagemaybepresentacrosstheNET-SandNET-Cpins.
• CheckforthecorrectterminationresistanceTurnoffnetworkpowerandcheckresistanceacrossNET-HandNET-LterminalsofanyT-pieceonthenetwork.Themeasuredresistanceshouldread60Ohms.
If120Ohmsismeasured,onlyoneterminationresistorisinstalled.Asecondresistorwillneedtobeinstalledattheoppositeendofthenetworktotheonethatisalreadypresent.
If40Ohmsisobserved,thereare3terminationresistorsinstalledonthenetworkso1willneedtoberemoved.Ifit’snotobviouswherethethirdresistoris,checkforanydevicesonthenetworkwithinstalledterminationresistorsandensuretheyareswitchedoff.
NetworkdeviceswithterminationresistorsinstalleddonotachieveNMEA2000certificationasthispracticecancauseconfusiononthenetwork.
Digging DeeperIfissuesremainwhenthecorrectpowerandresistancehavebeenprovedonthenetwork,furtherinvestigationwillberequired.
• HalfsplitmethodDisconnectonehalfofthebackboneandmovetheterminationresistortothenew,temporaryendofthenetwork.Iftheissueremainsyouhavenarroweditdowntothehalfofthenetworkthatisstillpoweredandactive.Iftheissuedoesnotremainitisinthehalfofthenetworkthathasbeendisconnected.Keepperformingthishalfsplitmethoduntilyouareabletonarrowitdowntoasingledevice,ifpossible.Don’tforgettomovetheterminationresistoreachtimetoensurethenetworkiscorrectlyterminated.
Oncetheissuehasbeennarroweddown,tryswappingoutt-piecesorcablingwithonesthatareknowntobegood.IfFieldFitConnectorshavebeenused,checkthewiringconnectionsinsidetoensurethattheyarecorrectandfirmlysecuredinplace.
Ifpossible,checkthewiringinsidethedeviceisproperlyandsecurelyterminated,ensuringtoobserveanti-staticprecautionsifexposinginternalelectronics.Itisalwaysbesttocheckthatthisisokwiththedevicemanufacturerbeforeperformingthissteptoensureyoudonotvoidanywarranty.
Ifanissuestillremainsyounowknowthereisaproblemwiththedeviceandit’stimetocontactthemanufacturerofthatdevice.
Checking availibility and accuracy of data on the network
• ActisenseNMEA2000toPCGateway(NGT-1)TobeabletoseeallofthedataontheNMEA2000networkandanalyseit,youwillneedtobeabletosendittoaPC.NMEA2000datacannotbereadbyaPCwithouttheuseofagateway,liketheNGT-1.
TherearetwooptionsofNGT-1available:
USBoption(NGT-1-USB):ThisistheeasiesttoconnecttoaPCasitcanbepluggedstraightintoyourPCsUSBport.TheNGT-1willbepoweredandactiveoncetheUSBdrivershavebeensuccessfully installed.DependingonyourOSsettingsthisshouldhappenautomatically ifyouhaveaworkinginternetconnection.IftheUSBdriversdonotinstallautomatically,thesameUSBdriversareavailableontheCDprovidedwiththeproductorformtheNGT-1downloadspageontheActisensewebsite.
ISOoption(NGT-1-ISO)TheISOoptionisforusersthatpreferaserialconnectiontotheirPC,insteadofUSB.IthasbarewiresonthePCsideforconnectingtoaserial(RS232)port.TheISOoptionispoweredbytheNMEA2000network.
ThedefaultbaudrateforbothoptionsofNGT-1is115200whichcanbechangedusingNMEAReader.
• NMEAReaderNMEAReaderissoftwarethatletsyouseeallofthedatabeingsenttoyourPCfromtheNMEA2000networkviatheNGT-1.TherearealsooptionsforconfiguringActisensedevices.NMEAReaderisfreelyavailabletodownloadfromtheActisensewebsite.
• ActisenseToolkitToolkitisnewsoftwarefromActisensethatiscurrentlyusedforconfiguringtheEngineMonitoringUnit(EMU-1)fromActisense.ItwillsoonsupportconfigurationofallconfigurableActisenseproductsandwillreplaceNMEAReaderwhenthe‘DataView’featurehasbeenadded.
FormoreinformationonhowtousetheNGT-1,NMEAReaderorToolkit,pleaserefertothemanualatactisense.com
http://www.actisense.com/media/?type=downloads
Who are the NMEA and What is NMEA 2000?Who are the NMEA?What is NMEA 2000?The Network That CANDeviceNetCertification
Minimum Network Requirements and Network LimitationsMinimum Network RequirementsCommon Phrases
NMEA 2000 Network LimitationsActisense Starter KitsThe original Actisense starter KitRIB Starter KitSmall Boat Network
Powering and fusing the networkPower T-PieceMicro Power CableSmall Boat NetworkQuick Network Block
T-Pieces and Termination ResistorsMicro T-PiecesMicro 4-Way T-Pieces
Connecting Devices and Extending the backboneTrunk and Drop CableBulk Cable
Field Fit ConnectorsField Fit Connectors
5 Steps to Field Fit Installation SuccessThe Quick Network BlockAt a GlanceDetailed OverviewRaymarine SeaTalkNG Solution
Network DiagnosisGlanded optionAdequate Power Supply & Termination ResistanceDigging DeeperChecking availibility and accuracy of data on the network