Siargo Thermal-D MF/FS4308 Series User manual

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Gas Mass Flow Meter VA.0
Model MF
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FS4308
© 2022 Siargo Ltd.
www.Siargo.com

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www.Siargo.com
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MF/FS4308
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UserManual
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
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Gas Mass Flow Meter
Withproprietarythermal‐D®sensingtechnology
MF/FS4308Series
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User Manual
DocumentNo. 08‐2022‐FSTD‐3EN
Issuedate:  2022.08
Revision:  VA.0
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SiargoLtd.
3100DeLaCruzBoulevard,Suite210
SantaClara,CA95054
USA
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Tel:+1(408)969.0368
Email:[email protected]
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©Copyright2022bySiargoLtd.
SiargoLtd.anditssubsidiariesreservetherighttochangethespecificationsand/ordescriptions
withoutpriornotice.Forfurtherinformationandupdates,pleasevisit:www.Siargo.com
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www.Siargo.com
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MF/FS4308
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UserManual
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
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Attention!
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Usewithcaution!
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Pleasecarefullyreadthismanualpriortooperatingthisproduct.
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Donotopenormodifyanyhardwarewhichmayleadtoirrecoverable
damage.
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Donotusethisproductifyoususpectanymalfunctionsordefection.
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Donotusethisproductforcorrosivemediaorinastrongvibration
environment.
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Usethisproductaccordingtothespecifiedparameters.
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Onlythetrainedorqualifiedpersonnelshallbeallowedtoperform
productservices.
Becautiousfortheelectricalsafety,evenitoperatesatalowvoltage,
anyelectricalshockmightleadtosomeunexpecteddamages.
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Thegastobemeasuredshouldbecleanandfreeofparticles.Donotapply
thismeterforliquidmedium.
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Donotapplyforanyunknownornon‐specifiedgasesthatmay
damagetheproduct.
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Forremotedata,pleasebesurethemeterisproperlyconfigured.

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www.Siargo.com
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MF/FS4308
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UserManual
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
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TableofContents
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1.Overview..................................................................................................5
2.Receipt/unpackoftheproducts................................................................6
3.Knowingtheproducts...............................................................................7
3.1.Productdescription.................................................................................................7
3.2.Poweranddatacabledescription.............................................................................7
3.3.Mechanicaldimensions............................................................................................8
4.Installation..............................................................................................10
5.OperationandMENUdescription..............................................................12
5.1Checktheproductspecifications............................................................................12
5.2Checktheleakage.................................................................................................12
5.3Powertheproductanddigitaldataconnection........................................................12
5.4MeterdisplayandMENUdescriptions.....................................................................13
5.4.1Meterdisplayandfunctionkeys........................................................................13
5.4.2MENUfunctioninputsequence.........................................................................13
5.4.3Detaileddescriptionsofthefunctions................................................................16
5.5RS485Modbuscommunicationprotocol.................................................................18
5.5.1Hardwareconnection.......................................................................................18
5.5.2Communicationparameters.............................................................................19
5.5.3Frame.............................................................................................................19
5.5.4Functioncodes................................................................................................20
5.5.5Registers........................................................................................................20
5.6I2Ccommunicationprotocol...................................................................................24
5.6.1I2Cinterfaceconnectiondiagram......................................................................24
5.6.2I2Cinterfaceread/writesequences.....................................................................24
5.6.3I2Cinterfacecommanddescription....................................................................25
5.6.4CRCchecksumcalculation................................................................................25

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www.Siargo.com
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MF/FS4308
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UserManual
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
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5.7Analogoutput(1.0~5.0Vdc).................................................................................26
5.8Pressureloss.........................................................................................................26
6.Productselectionandorderinformation....................................................27
7.Technicalspecifications...........................................................................28
8.Technicalnotesfortheproductperformance............................................29
8.1Measurementprinciple..........................................................................................29
8.2Precautionsforthebestperformanceoftheproduct................................................29
8.2.1Comparisonwithathird‐partyreferencemeter..................................................29
8.2.2Particlecontaminationandfluidiccleanness......................................................30
8.2.3Applytoadifferentgasmedium.......................................................................30
9.Troubleshooting......................................................................................31
10.WarrantyandLiability..............................................................................32
11.Service/ordercontactandotherinformation..............................................34
AppendixI:Productevaluationkit..................................................................35
AppendixII:Documenthistory.......................................................................36
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www.Siargo.com

MF/FS4308
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UserManual
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
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1. Overview
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Allcontactinformationcanbefoundattheendofthismanual.
ThismanualprovidesessentialinformationfortheoperationoftheMF/FS4308seriesofgasmass
flowmeters/sensorsforgeneral‐purposegasflowmonitorandcontrolapplicationswiththefull‐scale
massflowratefromupto50SLPMwithbothanaloganddigitaloutputs.Theproductperformance,
maintenance,andtroubleshootingaswellastheinformationforproductorder,technicalsupport,
andrepairarealsoincluded.
MF/FS4308massflowmeters/sensorsaredesignedforgeneral‐purposeprecisegasmetering,
processingmonitoring,and/orcontrol.Theproductshaveenhancedflowconditioningcomparedto
theMF/FS4008serieswhichallowsmoreflexibilityduringinstallation.Consequently,theproducts
willhaveapressurelossabout5timeshigherthanthatforMF/FS4008,butstilllowerthanmostof
theoffersonthemarketforasimilardynamicrange.MF/FS4308alsohasasmallerfootprint
comparedtoMF/FS4008.Itcanbeappliedforpneumaticcontrol,processautomation,andother
industrialapplicationswherethepressuredropisnotacriticalparameter.Theseriescoversawide
dynamicflowrangewithaworkingpressureratingofupto1.0MPa(10baror147PSI),anda
compensatedtemperaturerangingfrom‐10to55°C.
Theproductsaredesignedwithaneasychangeofmechanicalconnectors.Thestandardconnectors
areBSPT1/4”,one‐touchconnectorsof4mm,6mm,or8mm.Andothercustomizedconnectorsare
availableuponrequest.
ThesensingelementsaremanufacturedwithSiargo’sproprietaryMEMS(micro‐electro‐mechanical
systems)thermalmassflowsensingtechnologies(Thermal‐D®)thatmeasuresthecalorimetryand
diffusivityoftheflowmedium.Thesensorsurfaceispassivatedwithsiliconnitrideceramicmaterials
togetherwithwater/oilproofnano‐coatingforperformanceandreliability.Comparedtothe
conventionalcalorimetricflowsensingtechnology,thisuniquesensingapproachoffersbetter
linearity,removesgassensitivityforgaseswithsimilarthermaldiffusivities,andimproves
temperatureperformance.Itcanalsoauto‐recognizepre‐programmedgaseswithsignificant
differencesinthermaldiffusivity.Itisthefirstofakindintheindustrythatsensesthemassflowwith
multiplegaseswithoutamanualgasconversionfactor.Assuch,itensureshighprecisionforgas
measurementswithaircalibration.
Thermal-D ®isatrademarkofSiargo’sthermalsensingtechnology.
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www.Siargo.com

MF/FS4308

UserManual


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2. Receipt/unpackoftheproducts
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Uponreceiptoftheproducts,pleasecheckthepackingboxbeforedismantlingthepackingmaterials.
Ensurenodamagesduringshipping.Ifanyabnormalityisobserved,pleasecontactandnotifythe
carrierwhoshippedtheproductandinformthedistributorsorsalesrepresentativesiftheorderis
notplaceddirectlywiththemanufacturer,otherwise,themanufacturershouldbeinformedaswell.
Foranyfurtheractions,pleaserefertothereturnandrepairsectioninthismanual.
Ifthepackingboxisintact,proceedtoopenthepackingbox,andyoushallfindtheproduct(either
themeterwiththeLEDdisplayorthesensorwithoutthedisplaypertheactualorder).Thepower
anddatacableasshownbelowmayalsobefoundaccordingtothesamepackingmaterials.



 



Figure2.1:FS4308flowsensorFigure2.2:MF4308flowmeter  Figure2.3:datacable

Pleasecheckimmediatelyfortheintegrityoftheproductaswellasthepoweranddatacable,ifany
abnormalisidentified,pleasenotifythedistributor/salesrepresentativeormanufacturerassoonas
youcan.Ifanydefectsareconfirmed,anexchangeshallbearrangedimmediatelyviatheoriginal
saleschannel.(Note:theLEDdisplayshallnotbelitupuntilthepowercableispluggedin).Thisuser
manualshallalsoeitherbeincludedinthepackingboxorviaanonlinerequestforanelectronic
version.Inmostcases,thismanualshallbemadeavailabletothecustomerbeforetheactualorder.
ThestandardcablehasanAMPMODUMTE(5positions)compatibleconnectorwithalengthof0.5
meters.




www.Siargo.com

MF/FS4308

UserManual


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3. Knowingtheproducts

3.1. Productdescription









Figure3.1:MF/FS4308partsdescription

3.2. Poweranddatacabledescription

     Table3.1:MF/FS4308pin/wireassignments.

 



Figure3.2:MF/FS4308connectionandcable

Note: 1.ThestandardcablehasanAMPMODUMTE(5positions)compatibleconnectorwithalengthof0.5
meters.
2.Theproductofferstwodigitalcommunicationsasoptions,I
2
CorRS485thatcanbeselectedatthe
timeoforder.ThesetwocommunicationprotocolssharetheportsasdefinedinTable3.1.Forthe
detailedprotocolsofthecorrespondingoption,pleaserefertoSection5.
3.TheRS485Modbusisasynchronous,half‐duplexcommunication.Whenthedataaretransmitted
orreceivedfromtheproduct,theotherpinisservingastheground.
Wire Color Definition
1

Blue

RS485B

(‐)


/


SDA,

I
2
Cdata

2GreenAnalogoutput,1.0~5.0Vdc
3RedPowersupply,8~24Vdc
4BlackGround
5YellowRS485A(+)/SCL,I
2
Cclock
Exchangeable
connector

LEDdisplay
MENUkeys
Exchangeable
connector
Flowdirection
Electricalinterface,
AMPMTE,5positions
Meterbody Sensorbody
Statusindicator

Installationscrews
(bottom)



www.Siargo.com

MF/FS4308

UserManual


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3.3. Mechanicaldimensions
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Figure3.3:FS4308dimensionswithBSPT(R1/4”)connectors.




Figure3.4:FS4308dimensionswithone‐touchconnectors.

8mmOne‐touch
6mmOne‐touch
4mmOne‐touch



www.Siargo.com

MF/FS4308

UserManual


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Figure3.5:MF4308dimensionswithBSPT(R1/4”)connectors.


. 

Figure3.6:MF4308dimensionswithone‐touchconnectors.

Note: *Otherthreadsorcompressivetypescanbecustomized.

8mmOne‐touch
6mmOne‐touch
4mmOne‐touch



www.Siargo.com

MF/FS4308

UserManual


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4. Installation

Donotopenoralteranypartoftheproductwhichwouldleadtomalfunctionandirrecoverable
damage.Itwillalsoforfeitthetermsofthewarrantyandcauseliability.
Theproductatthetimeofshipmentisfullyinspectedforitsqualityandmeetsallsafetyrequirements.
Additionalsafetymeasuresduringtheinstallationshouldbeapplied.Thisincludes,butisnotlimited
totheleakageverificationprocedures,standardEDS(electrostaticdischarge)precautions,andDC
voltageprecautions.Othertaskssuchascalibration,partreplacement,repair,andmaintenance
mustonlybeperformedbytrainedpersonnel.Uponrequest,themanufacturerwillprovide
necessarytechnicalsupportand/ortrainingforthepersonnel.
Therearenopreferredspacedirectionsfortheinstallation.Theflowdirectionshouldbealignedwith
thearrowmarkonthemeterbody.Iftheflowingfluidmayhaveparticlesordebris,afilterisstrongly
recommendedtobeinstalledupstreamofthemeter.
Pleasefollowthefollowingstepstocompletetheinstallation:
a)Uponopeningthepackage,theproduct'sphysicalintegrityshouldbeinspectedtoensureno
visualdamage.
b)Beforeinstallationoftheproduct,pleaseensurethatthepipedebrisorparticlesoranyother
foreignmaterialsarecompletelyremoved.
c)Closetheupstreamvalve,ifany,completely.
d)Duringinstallation,pleasemakesurenoforeignmaterials(suchaswater,oil,dirt,particles,etc.)
entertheinstallationpipeline.
e)ConnectelectricalwiresperthewiredefinitioninTable3.1.Pleasebesureofthepowersupply
range(i.e.,8~24Vdc)andpowersupplypolarization.Ifanadapterisused,makesurethe
adaptermeetsindustrialstandardsandhasallsafetycertifications.Alternatively,thisproduct
canalsobepoweredbya9Vdcbattery.
f)Forthedatacommunicationwireconnection,pleasefollowthedescriptioninTable3.1andmake
surethatthewiresarecorrectlyconnectedtotheproperportsonyourdatadevice/equipment.
Pleasemakesurethedatacablemeetsindustrialstandardswithpropershielding.
g)Oncetheexternalpowerissuccessfullyconnected,fortheMFserialofmeters,theLEDshould
belightedupwiththeproperinformationdisplayed.
h)Slowlyopenthevalve(s)ofthegassupplyifany,upstreamordownstream,orbothofthe
pipelines.theproductshouldthenstarttomeasuretheflowinthepipeline.Note:becausethe
meterhasalargedynamicalmeasurementrange,itcouldbenormalifyouseethesmallinstant

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UserManual
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flowrateevenifthereis“noflow”inthepipeline.Ifthevalueisconsistentlypresent,double‐
checkthepipeleakageandthenresettheoffsetifyouaresurethereisnoleakageorflow.
h)Thiswillconcludetheinstallation.


Cautions
a)Don'talteranypartsoftheproduct.
b)Ensuretheelectricalconnectionisproperlydonepertheinstructions.
c)Makesurenomechanicalstressesintheconnections.
d)Thestrongelectromagneticinterferencesourcesclosebyoranymechanicalshocksatthe
pipelinemayalsocreatemalfunctioningoftheproduct.
e)Slowlyopen/closevalvesatthegassupplypipingtopreventabruptpulseflowimpact.


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MF/FS4308
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UserManual
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5. OperationandMENUdescription

5.1 Checktheproductspecifications

Beforestartingtousethisproduct,checktheproductspecificationsthatcanbefoundinthismanual
orthebasicinformationfromthedatasheetatthecompany’swebsitewww.Siargo.com.
ThedetailedproducttechnicalspecificationscanbefoundinSection7.Foraspecificapplication,
thepressureratingmustnotbehigherthanthesystempressuretobemeasured,andtheflowrange
shouldalsobewithinthespecifiedones.Inmostcases,theuseofahighfull‐scalerangedmeterfor
theverylowflowratemeasurementoftenresultsinerroneousdata.Thegastobemeasuredmust
alsobeconsistentwiththatspecifiedbytheproduct.Beparticularlycautiousaboutthesupplied
voltageindicatedinthespecification.Ahighervoltagemayleadtoirrecoverabledamage,anda
lowervoltagewillnotpowertheproductforanydesiredfunctions.
Forthebestperformanceoftheproduct,itisadvisedthatthegastobemeasuredmustbecleanand
freeofparticlesorotherforeignmaterials.

5.2 Checktheleakage

Checkgasleakagebeforeanymeasurement.Ifitisneeded,pressurizednitrogenoraircanbeused
fortheleakagecheck.

5.3 Powertheproductanddigitaldataconnection

AlthoughthisproductcomplieswiththeCE‐requiredEMCregulations,italsorequirestheproductto
beusedaccordingtothestandardelectricaldevicepractice.Beforeconnectingtheproductwith
externalDCpoweroranAC‐DCadapter,makesurethesupplyvoltageiswithintherangeofthe
specifiedonesinSection7.BecautiousthatstandardelectricaldeviceprecautionssuchasEDS
(electrostaticdischarge)andDCvoltageareobserved.Excessiveelectrostaticdischargemay
damagetheproduct.
Themanufacturer‐suppliedpoweranddatacablehavealockingfixture.Lockthecableandmake
sureitisproperlyengagingandwillnotbeaccidentallygotunplugged.
Half‐duplexRS485ModbusorI2Cisusedfordigitaldatacommunication.Makesurethewiresare
properlyconnectedtothereceiverside.

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MF/FS4308
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5.4 MeterdisplayandMENUdescriptions

Pleaseskipthissectionforflowsensorproducts.
5.4.1 Meterdisplayandfunctionkeys




Figure5.1:MF4308displayandfunctionkeys
Themeterhasafront3‐keyboardfortheusertosetthedesiredfunctions,accessdata,andcheck
thestatus.TheMenukey(M)isattheupperrightpositionwhichallowstheusertoselectafunction
andconfirmationorotherrelatedactionsthatwillbedetailedanddescribedintheMENUkey
sequencegraphicpresentation.Twokeys(“Up”and“Down”)areusedtoselectthefunctions.The
twoLEDlights(IandII)areusedfortheindicationofdisplaycontents.Forthedefaultinstantflow
ratedisplay,bothofthesetwoLEDswillbeoff.Pleaserefertothedetailedinformationbelow.
ThedefaultinstantflowrateisSLPMwith4digits,oneofthedigitsisadecimal.Whentheflowrate
isabovethespecifiedflowrange,LEDIwillflashfortheflowratesabovetheupperlimit,andLEDII
willflashfortheflowratesbelowthelowerlimit.IfbothLEDsareflashing,thedisplayedvaluesare
incorrect.
Oncethepowerissuppliedandnoabnormalissuesareobserved,themeterisreadytoperformthe
measurements.WhiletheLEDdisplaystheinstantmassflowrate,theaccumulatedortotalizedflow
ratecanbeaccessedbypressingthe“Up”or“Down”key.Theaccumulatedflowrateisregistered
with“standardliter”(SL),andthemaximumcanbe99,999,999SL.Thefirstfourdigitsofthe
accumulatedflowrateareindicatedbythe“I”LEDlight,andthelastfourdigitsarerepresentedwhen
the“II”LEDlightison.The“I”and“II”LEDlightswillbeautomaticallyswitchedwhenthe
accumulatedflowrateisdisplayed.Theaccumulatedflowratewillbeautomaticallysavedevery
threeminutes.Atthetimeofthepowerfailureorcut‐off,thevaluewillberepresentingthelatest
savedones.

5.4.2 MENUfunctioninputsequence

Attheflowmeasurement(main)display,pressthethreeMEMUkeys,itwillallowtheusertoperform
avarietyofsettingsoftheproduct.Thefollowinggraphdetailsthekeysequenceforeachfunction,
andsomedetailedexplanationsarefollowedafterthegraphicpresentation.




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Figure5.2:MF4308menuflowchart



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MF/FS4308
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UserManual
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Table5.1:On‐screencharactersandtheircorrespondingfunctions
On‐screencharacter SymbolFunctions
0.unL/LocUnlock/lockthekeyboard
1.oFF/onResettheaccumulatedflow
2.oFF/onResetorcalibratetheoffset
3.1…247
SettheModbusaddress
Available:1~247,
Thedefaultaddressis1.
4.1/2/5/10/
20/50/100Settheresponsetime
5.25/50/100/
200Setthedisplayrefreshrate
6.0…110
Settheupperflowratealarm
Available:0~110,meansof0%~110%
fullscale.
Thedefaultvalueis100(100%fullscale).
7.0…110
Setthelowerflowratealarm
Available:0~110,meansof0%~110%
fullscale.
Thedefaultvalueis0(0%fullscale).
8.0/1/2/3Setthedisplaydecimal
9.48/96/192/384

Setthecommunicationbaudrate
Available:48,96,192,384,meansofbaud
rate4800,9600,19200,38400.
Thedefaultvalueis384(baudrate38400).

A.10…999
SettheGCF(gasconversionfactor)
Available:10~999,meansofGCF=100~
9990.
Defaultvalueis100,meansofGCF=1000.

b.0/1Settheaccumulatedflowrateunit:
b.0‐SL,b.1‐Nm
3
.
Note:Duringthisprocess,themeterwillcontinuetomeasuretheflowwithoutbeinginterrupted.






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5.4.3 Detaileddescriptionsofthefunctions
0) Keyboardsecurity
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Thisfunctionallowstheusertodisablethekeyboardentryafterthemeterissetasdesired.It
willpreventanyaccidentalkeyentrythatmayalterthesettings.AttheMENU,select“lock”
tolockthekeyboard.
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1) Resettheaccumulatedflowrate
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Themaximumaccumulatedflowratethatcanberegisteredbythemeteris99,999,999SL.
Oncethevalueisreached,theaccumulatingfunctionwillstopprocessingthedata.Itis
necessarytoresettheregisterforthecontinuationofthisfunction.
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Usethisfunctionwithcautionasitwilldeleteallcurrentaccumulatedflowratedata.
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2) Resetorcalibratetheoffset
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Sometimesorafteralongtimeofuse(i.e.,over1yearofusage),thesensorsurfacecould
haveathindepositfromtheenvironmentifthegasisnotsuperclean.Dependingonthe
actualcase,thisdepositmightormightslightlychangethethermalsensitivityofthesensor
resultinginadriftoftheoffsetoratinyflowatthezeroflowinthepipeline.Usingthis
functiontoresettheoffsetwillnothaveanimpactonthemeterperformanceifsuchanoffset
isoutsideofthe100:1calibratedrange.
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Usethisfunctionwithcautionandmakesurethereisnoflowwhenexecutingthisfunction,
otherwise,itmayincursomeadditionalerrorsinthemeasurement.
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3) SettheModbusaddressofthemeter
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UsethisfunctiontosettheRS485Modbusaddressofthemeter.Thissettingcanalsobe
doneviatheRS485communication.
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4) Settheresponsetime
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Usethisfunctiontochangetheresponsetimeofthemeter.Thedefaultoneis10msec.
Increasingtheresponsetimewillallowmoredatatoaverageandoutputastablerflowrateif
theactualflowratemayhavesomeundesiredfluctuation.
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Availableresponsetimeis10msec(4.1);20msec(4.2);50msec(4.5);100msec(4.10);200
msec(4.20);500msec(4.50),and1000msec(4.100)

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MF/FS4308
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5) Setthedisplayrefreshrate
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Changingthedisplayrefreshratewilljustalterthedisplayupdatetime,itwillhavenoimpact
onthemeter’smeasurement.Thedefaultrefreshrateis250msec.
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Availablerefreshratesare250msec(5.25);500msec(5.50);1000msec(5.100),and2000
msec(5.200).
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6) Settheupperflowratealarm
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Thisfunctionallowstheusertosetamaximumallowableflowrateabovewhichanalarmwill
betriggeredwithaflashingscreen.
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7) Setthelowerflowratealarm
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Thisfunctionallowstheusertosetaminimumflowratebelowwhichanalarmwillbe
triggeredwithaflashingscreen.
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8) Setthedisplaydecimal
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Theusercanusethisfunctiontoalterthedefaultdecimaldisplay.Optionsarelistedbelow
foreachflowrange:
Table5.2:decimaloptions
FlowrangeDecimaloptions
0
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~
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10,20,
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30,40,
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50
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SLPM
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0,1,2
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9) Setthecommunicationbaudrate
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ThisfunctionallowsaMENUentryoftheRS485communicationbaudrate.
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10) SettheGCF(thegasconversionfactor)
Themeterisnormallycalibratedwithairat20°Cand101.325kPa.Whentheuserwantsto
setthestandardconditionsotherthanthespecifiedtemperatureorappliesthemeterfor
otherallowablegases(pleasecontactthemanufacturerforthelistofgases),itispossibleto
usethisgasconversionfactorfunctiontoensurethereadingsarecorrectanddesired.
ThedefaultvalueoftheGCFis1000(1.000).Forexample,ifonewantstoalterthestandard
temperatureto0°C,thefactorcanbecalculatedusingthegasequation:PV/T=constant:

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MF/FS4308
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GCF=1000xV(new)/V(20°C)=T(o°C)/T(20°C)=1000x273/293=932
Thenthegasconversionfactorwouldbe932.
Insomecases,theactualsystemmayhaveaconstantdeviationfromthatatthecalibration,
thisGCFcanalsobeusedtoadjust.Foradditionalinformation,pleasecontactthe
manufacturer.
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11) Settheaccumulatedflowrateunit.
TheaccumulatedflowrateunitcanbesettoSLorNm3.
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5.5 RS485Modbuscommunicationprotocol
ThedigitalcommunicationprotocolisbasedonthestandardModbusRTUHalfplexmode
communicationprotocol.Amaster(PCorPLC)cancommunicatewithmultipleslaves(thecurrent
product)fordataexchangeandcommunicationparameterconfiguration.RefertoTable3.2forthe
cableconnection.
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5.5.1 Hardwareconnection
TheRS485hardwarelayerisTIA/EIA‐485‐A,asillustratedbelow.Inthisconfiguration,theproduct
(MF/FS4308)isaslave.
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Figure5.3:RS485hardware
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5.5.2 Communicationparameters
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ThePCUARTcommunicationparametersarelistedintable5.3.
Table5.3:PCUARTcommunicationparameters
ParametersProtocol
RTU
Baudrate(Bitspersecond)
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38400bps
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Startbits1
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Databits8
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Stopbits1
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Even/OddparityNone
Bitsperiod104.2µsec
Bytesperiod1.1458msec
Maximumdatalength20
Maximumnodes247
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5.5.3 Frame
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TheframefunctionisbasedonthestandardModbusRTUframing:
Table5.4:framefunction
Start_bitsAddress
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Functioncodes
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DataCRCStop_bits
T1‐T2‐T3‐T48bit8bitN8bit(20≥n≥0)
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16bitT1‐T2‐T3‐T4
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Start_bits:4periodsbittime,foranewframe.
Address: Theaddresscanbesetfrom1to247exceptfor157(0x9d).0isthebroadcastaddress.
Functioncodes: Definetheproduct'sfunctions/actions(slaves),eitherexecutionorresponse.
Data: Theaddressoftheregister,lengthofdata,andthedatathemselves.
CRC: CRCverificationcode.Thelowbyteisfollowedbythehighbyte.Forexample,a16‐bit
CRCisdividedintoBYTE_HandBYTE_L.Intheframing,theBYTE_Lwillcomefirst,then
followedbytheBYTE_H.ThelastoneistheSTOPsignal.
Stop_bits: 4periodsbittime,forendingthecurrentframe.
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