Sutron Accubar SDI-12 Manual

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SDI‐TB
SDI‐12TippingBucketInterface
withSmartCompensation
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Operations&Maintenance
Manual
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PartNo.8800‐1205
Revision1.1
25May2018
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SutronCorporationSDI‐TBUsersManual   Rev.1.1 5/24/2018 pg.2
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TABLEOFCONTENTS
1.Introduction.....................................................................................................................................3
2.QuickStart.......................................................................................................................................3
2.1Unpacking...........................................................................................................................3
2.2Operation...........................................................................................................................4
2.3Connections........................................................................................................................7
2.4SensorConfiguration..........................................................................................................7
3.CommandReference........................................................................................................................8
3.1StandardSDI‐12commands...............................................................................................8
3.2ExtendedSDI‐12commands............................................................................................11
AppendixA:Specifications&OrderingInformation......................................................................15
AppendixB:CustomerServicePolicy............................................................................................16
AppendixC:CommercialWarranty...............................................................................................18
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SutronCorporationSDI‐TBUsersManual   Rev.1.1 5/24/2018 pg.3
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1. Introduction
TheSDI‐TBisanultralowpower,compactandruggedSDI‐12raingaugesensor.Itcanbeconfiguredtowork
withmosttippingbucketsizesandconfigurationsandsupportsacorrectionpolynomialforhighrainfallrate
compensation.TheSDI‐TBalsohasnumerousbuiltinfeatureslikeprogrammabledailyrainfallresettime,
programmableyearlyreset.TheSDI‐TBsensorhasabackuppowersourcethatpermitsun‐interrupted
operationforupto10hoursincaseSDI‐12powerislost.
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2. QuickStart
2.1 Unpacking
RemoveSDI‐TBsensorfromtheshippingcontainerandvisuallyinspecttheunitforsignsofdamage
duringshipment.Reportanysuchdamagetothefactoryimmediatelytoensureapromptresponseand
resolution.Retainoneshippingcontainerintheeventafactoryreturnisnecessary.
Pleasenotethatifareturnisrequired,areturnmaterialauthorization(RMA)numberisrequired.Toget
thisRMAnumber,calltheSutronCustomerServiceDepartmentat703‐406‐2800.
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SutronCorporationSDI‐TBUsersManual   Rev.1.1 5/24/2018 pg.4
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2.2 Operation
IMPORTANT:OnpoweringuptheSDI‐TBforthefirsttime,theSDI‐TBrequiresabout2minutesforthe
internalcapacitortochargeupandthesupplyvoltagetogetuptotheminimumvoltagethreshold
requiredforthemoduletobeoperational.Thecapacitortypicallytakesabout10hourstodischarge
oncecompletelycharged
Readinganyoftheseregisterswillinitiateanewmeasurementandthemeasuredvaluewillbereturned.
TheSDI‐TBprovidesastandard3‐wireSDI‐12bustointerfacewithanySDI‐12v1.3compliantloggerand
a2‐wireinterfaceforconnectiontostandardTippingbuckets.
MostTippingbucketsconsistofabucketattachedtoasimpleswitch.Theswitchmakesabriefcontact
betweenthetwowiresasthebuckettips.TheSDI‐TBincrementsthecumulativetotalanddailyrainfall
andrawtipcountforeachtipitrecords.TheSDI‐TBcanbeconfiguredtorecordatiponafallingedgeor
risingedge.Apull‐uporpull‐downresistorisautomaticallyactivedependingonwhetherafallingedge
orrisingedgerespectivelyhasbeenconfigured.
Auserprogrammabledebouncingdurationcanbeconfiguredtofilteroutnoiseduringthevoltage
transitionsastheswitchmakes/breakscontact.
TheSDI‐TBusesaconfigurable‘Bucketsize’orathirdordercompensationpolynomialtoconverttips
intorainfall.Thebucketsizeindicatestheamountofrainfallthatcorrespondstoasingletipofthe
bucket.Bydefault(ifnocompensationhasbeenprogrammed)theSDI‐TBincrementsthetotal
accumulationaftereachvalidtip.Thenewaccumulationsiscalculatedusingtheformula
    
Sincethebuckettakesafiniteamountoftimetotipoverandstartfillingagain,somerainwillbelost
beforethebucketisinpositiontocollectrainagain.Thisamountofrainfalllostwillbecomemore
significantastherainfallrateincreases.Tocompensateforsuchheavyrainfallrates,theSDI‐TBsupports
athirdorderpolynomialwithuserconfigurablecoefficients.Thepolynomialisusedtocomputethe
rainfallforeachtipbasedonhowfrequentlythebuckettips.Thepolynomialisoftheform
/  
 
Thecoefficientscanbeobtainedbyplottingtherainfallininches/houronthex‐axisandthe
compensatedrain(inches/tip)ontheY‐axisandfittingtheresultantcurvetoathirdorderpolynomial.
Thefollowingplotshowsthecurvefora0.01inchbucket.

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SutronCorporationSDI‐TBUsersManual   Rev.1.1 5/24/2018 pg.5
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TheSDI‐TBmeasuresthetimebetweenthecurrenttipandtheprevioustipandusesthebucketsizeto
computetheequivalentrainfallininches/hour.Thepolynomialisthenusedtoconverttheresultant
rainfallininches/hourtorainfallpertip.Ifthecoefficientshavenotbeenconfigured,thebucketsizeis
used.
TheSDI‐TBhasaninternalRealTimeClock(RTC)thatisusedtokeeptimeandcanbeprogrammedto
performdailyandannualrainfallresets.
TheSDI‐TBhasabuiltinrechargeablebackuppowersourcethatisusedtopowerthemoduleforupto
10hoursofuninterruptedoperationincaseSDI‐12powerislost.Thecurrentdrawwillbehigherduring
thechargingphaseandreduceovertime,tillthebackuppowersourceiscompletelycharged.
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0.009
0.0095
0.01
0.0105
0.011
0.0115
0.012
0.0125
0.013
0.0135
0 5 10 15 20 25 30
Inches/tip
Rain(inches/hour)

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SutronCorporationSDI‐TBUsersManual   Rev.1.1 5/24/2018 pg.6
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Fig:ChargingcurrentvsTime
TheinternalRTCandTippingbucketinterfacesarefullyfunctionalwhilerunningoffthebackuppower
source.However,theSDI‐12interfaceisdisabledwhilerunningoffbackuppower.TheSDI‐12interface
functionalityisautomaticallyrestoredwhenSDI‐12powerisrestored.
TheSDI‐TBisfullycompliantwiththeSDIprotocolv1.3The‘D0’commandissuedafteran‘M’command
returnsvariousaccumulationsandcountervalues.
Foreg
Command=aM!
Response=a0005
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Command=aD0
Response=a+<acc_last>+<raw_tip_year>+<acc_year>+<acc_daily>+<acc_yest>
<acc_last>=totalaccumulationssincethelastMcommandwasissued.EverytimeanM
commandisissued,thisparameterwillbereset.
<raw_tip_year>=TheSDI‐TBcanbeprogrammedtoresetitsannualcounters/accumulationat
thestartofarainyear.Thisparameterreturnsthetotalrawtipcountsforthecurrentrain‐year.
<acc_year>=Thisparameterreturnsthetotalrainfallforthecurrentrain‐year.
<acc_daily>=TheSDI‐TBcanbeprogrammedtoresetthedailyrainfallvalueonceeveryday.
Thisparameterreturnsthetotalrainfalltoday.
<acc_yest>=Thisparameterreturnsthetotalaccumulationyesterday.Eachtimethedaily
accumulationisresetbythedailytimer,thetotalaccumulationtodayissavedasyesterday’s
accumulation.
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SutronCorporationSDI‐TBUsersManual   Rev.1.1 5/24/2018 pg.7
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2.3 Connections
TheSDI‐TBsensorisverysimpletoconnectandgetworking.Theunithasa5positionpushheaderfor
interfacingwithanSDIloggerandastandard2‐wireTippingbucket.
PinLabelDescription
TB‐INConnecttothereedswitchterminalofthetippingbucket.
GNDGroundconnectionfortheTippingbucket
SDI‐12Data BidirectionalSDIdatabus
GNDSDI‐12interfaceGroundconnection
Power(4v‐20vSDI‐12powerfromthelogger/SDI‐12master
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2.4 SensorConfiguration
TheSDI‐TBsensorsareconfiguredatthefactorytothedefaultSDIaddress0.IfotherSDI12sensorsare
presentontheSDI12bus,theaddressmustbechangedusingthestandard‘addresschange’command.
RefertotheSDI‐12commandtablebelowforinstructionsonhowtochangetheaddressifneeded.
TheSDI‐TBhasadefaultdebouncingof15ms.Ifthebuckethasaswitchclosetimeotherthan15ms,the
appropriatedebouncedurationcanbesetusingtheXDBNCcommand.
IfthetippingBucketbeingusedhasacapacityotherthanthedefaultsize(0.01”),thebucketsizemust
besetusingtheXBKTSZcommand.
Ifthetippingbucketbeinguseddoesnothaveasiphonortheuserwishestocompensateforheavy
rainfallrates,theXCOMPcommandmustbeusedtosetthepolynomialcoefficients.
TheSDI‐TBsensorisSDI‐12compliantandwillrespondtoallSDI‐12commandsaccordingtoversion1.3
ofthestandard.TousetheSDI‐12commandsyoumusthaveadataloggerorinterfacethatsupports
theSDI‐12standard.MoredetailsontheSDI‐12interfacecanbefoundathttp://www.sdi‐12.org.
ThegeneralformofanSDI‐12commandis:
aC!<CR><LF>
Whereaisthesensoraddress0‐9,A‐Z,a‐z,*,?.(Addresses*and?willaddressanysensor,regardlessof
itsaddress.)
Cisthecommandand!isthelastcharacterofthecommand.

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SutronCorporationSDI‐TBUsersManual   Rev.1.1 5/24/2018 pg.8
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ItisexpectedthattheuserisfamiliarwiththeSDI‐12protocolandthissectioniswrittenaccordingly.
3. CommandReference
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3.1 StandardSDI‐12commands
CommandNameCommandResponseNotes
?QuerySDI
Address?!
A
where
a=address
OnlyoneSDI‐12
deviceshouldbe
connectedtothebus
sinceallwillrespond.
Acknowledge
Activea!A
ISend
IdentificationaI!
Foramastertheexpected
responseis
a13SUTRONSDI‐TBsssssssvx.xx
a
13
SUTRON=manufacturer
SDI‐TB=modelnumber
sssssss=Serialnumber
x.xx=softwarerevisionnumber
Identificationstring
forSDI‐TBsensor.
AChange
Address
aAb!

Example:
0A5!
b
Indicatingnewaddress
example
5




SutronCorporationSDI‐TBUsersManual   Rev.1.1 5/24/2018 pg.9



CommandNameCommandResponseNotes
M
MC
C
CC
Get
accumulation
andrawtip
values
aM!
(orMC,C,CC)
Ex:
8M!

aD0!
Ex:
0D0!


a0005
5valuesavailablein0seconds.
UseD0toretrievedata.
a+<acc_last>+<rawtip_years>
+<acc_year>+<acc_daily>+<acc_yes
t>
where:
a=Sensoraddress
<acc_last>=Rainfallsincelast
measurement
<raw_tip_years>=Totalrawtips
thisyear
<acc_year>=Totalaccumulation
thisyear
<acc_daily>=Totalaccumulation
today
<acc_yest>=Totalaccumulation
Yesterday
Ex:
0+0.01+12+0.12+0.03+0.02
Returnsthecurrent
accumulationvalues
andresetsthe
accumulatedrainfall
sincelast
measurement.
M1
MC1
C1
CC1
Getrainfallin
last‘x’
minutes.
aM1!
(orMC1,C1,
CC1)
Ex:
0M1!

aD0!
Ex:
0D0!

a0002
2valuesavailablein0seconds.Use
D0toretrievedata.

a+<acc_x_minutes><x>

where:
a=address
<acc_x_minutes>=rainfall
<x>=durationforwhichrainfallis
reported

Ex:
0+0.03+15
Returnstheainfallin
thelast‘x’minutes,
wherexcanbeset
usingtheextended
command‘XIDUR’
describedthe
‘ExtendedSDI‐12
commands’table.




SutronCorporationSDI‐TBUsersManual   Rev.1.1 5/24/2018 pg.10
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