contents · b1.1 classification of communication environment and expected communication distance...

TechnicalInformation

Guidelines for Layout and Installation of Field Wireless Devices

TI 01W01A51-12EN

TI 01W01A51-12EN©Copyright Aug. 2013 (KP)1st Edition, Aug. 2013 (KP)

Yokogawa Electric Corporation2-9-32, Nakacho, Musashino-shi, Tokyo, 180-8750 JapanTel.: 81-422-52-5634 Fax.: 81-422-52-9802

ContentsIntroduction ......................................................................................................2Revision Information .......................................................................................3Terms and definitions .....................................................................................4Overview ...........................................................................................................5Part A. Layout and Topology of Wireless Devices ....................................6

A1. Star topology ...................................................................................................6 A2. Mesh topology .................................................................................................7

Part B. Guidelines for Device Layout and Installation ..............................8B1. Communication distance .......................................................................................8

B1.1 Classificationofcommunicationenvironmentandexpected communicationdistance ........................................................................8

B2. Installation procedure ..........................................................................................10B2.1 Selecting the star topology ..................................................................10B2.2 Selectingthemeshtopology ...............................................................11B2.3 Configuringthemeshtopologywiththreeormorehops ....................12B2.4 Other installation procedures: using high-gain antennas ....................13B2.5 Other installation procedures: using extension antenna cables .........14

B3. Using routers .........................................................................................................15B3.1 Installingrouterssothatalltransmittershavetwocommunicationpaths ..15B3.2 Installing routers as high as possible ...................................................15B3.3 Using a 2 dBi antenna for routers ........................................................15B3.4 Examplesofrouterinstallation ............................................................16

Part C. Guidelines for Implementing the Site Survey .............................17C1. Installation design with a site plan/device layout only (visual assessment and site survey are not required) .....................................17C2. Installation design with a site plan/device layout and visual assessment (site survey is not required) .................................................................................17C3. Installation design requiring a site survey ........................................................17

Part D. Examples of Installation Design Not Requiring Site Surveys ...19D1. Installation guidelines are followed ....................................................................19D2. Devices are mounted on rotating objects ..........................................................19D3. Devices are installed in a small space (50 m square or smaller) ....................20

Part E. Examples Clearly Requiring Site Surveys...................................21E1. Installation in a place surrounded by metal walls .............................................21E2. Wi-Fi communication close to the field wireless system .................................22

Reference 1: Fresnel Zone .....................................................................................................23Reference 2: Requirements for Antenna Installation ..........................................................25Reference 3: Packet Error Rate (PER) ..................................................................................26

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Introduction

IntroductionThisguidelineexplainshowtoinstallfieldwirelessdevicesinasystemwiththeYFGW410fieldwirelessmanage-mentstationandYFGW510fieldwirelessaccesspoint,andhowtodeterminewhetheractualcommunicationtestsareneeded.Layoutexamplesthatcomplywiththeguidelinesarealsoshown.

Thefollowingsymbolsareusedintheproductanduser’smanualtoindicatesafetyprecautions:

CAUTIONThissymbolindicatescautionsrequiredwhenhandlingtheproduct.Thissymbolisplacedonpartsoftheprod-uctrequiringreferencetotheuser’smanualtoprotecttheoperatorandtheproductitself.Intheuser’smanual,thissymbolisaccompaniedbyprecautionstoavoidphysicalinjuryordeathoftheoperator,includingelectricalshocks,injury,andothers.

WARNINGThissymbolindicatesinstructionsthatmustbeobservedtopreventthesoftwareorhardwarefrombeingdam-agedorthesystemfrombecomingfaulty.

IMPORTANTThissymbolindicatesimportantinformationrequiredtounderstandoperationsorfunctions.

All Rights Reserved. Copyright © 2013, Yokogawa Electric Corporation

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Revision Information

Revision InformationTitle: Guideline for layout and installation of field wireless devices

Manual No.: TI 01W01A51-12EN

Edition Date Page Revised Item1st August 2013 New Issue

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Terms and definitions

Terms and definitionsl Visual assessmentAvisualassessmentinvolvesvisuallyevaluatingthesitetochecktheline-of-sightofwirelesscommunicationpaths,howtoinstallwirelesstransmitters,howtofeedpowertoaccesspoints,andhowtolayoutthecommunica-tionpathstotheuppersystem.

l Site surveyAsitesurveyisanactualcommunicationtestwithequipmentatproposedinstallationpointstocheckthereliabilityofwirelesscommunicationpaths.

l Access point (AP)Inthisdocument,theYFGW510fieldwirelessaccesspointisreferredtoasanaccesspoint(AP).

l Router (RT)Inthisdocument,adevicethatrelayswirelesscommunicationisreferredtoasarouter(RT).

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Overview

OverviewYokogawa’sfieldwirelesssystemconformingtotheISA100.11astandardfeaturesalongcommunicationdis-tancewithlowerrorrateandhighreceiversensitivity.Thesystemisdesignedforcustomerswhorequirereliabil-ity,performance,andfutureinnovation.Tomakefulluseoffieldwirelessdevices,theoptimalinstallationlayoutisrequired.

Althoughconditionsatinstallationsitesdifferfromplacetoplace,astudyofthesiteplan/devicelayoutorvisualassessmentisusuallyenoughtoensureasuccessfulinstallation.Theseassessmentsassureefficientnetworkdesignandreliablecommunications.However,anactualcommunicationtestisrecommendedtoconfirmthereli-abilityofcommunicationpathsandtofindtheoptimumlayoutinharshenvironmentsforwirelesssignals.

Communicationdistanceisakeyindicatoroftheperformanceofwirelessdevices.Wirelessdeviceswithlongercommunicationdistanceusuallyhavehigherperformance.Wirelesscommunicationdistanceisevaluatedwiththepacketerrorrate(PER).Underidealcircumstances,thePERcorrelatesdirectlywiththereceivingsignalstrengthindicator(RSSI),andthusthePERcanbepredictedfromthevalueofRSSI.However,RSSIcorrelatespoorlywithPERinaplacesurroundedbymetalstructuresbecauseofmultipathfadingandobstacles.Therefore,YokogawadirectlyusesthePERasanevaluationparameter.

Thefieldwirelesssystemre-sendspacketswhenwirelesscommunicationfails.IfthePERishigh,thesystemrepeatedlysendslostpackets,whichdelaysthedatafromwirelesstransmittersreachingtheuppersystem.Inaddition,wirelesssignalsareoftenreflectedoffmanymetalstructuresinaplant,causingthePERtobecomeunstable,andthedegreeofdelaytofluctuate.Withalongdelay,thesystemmaynotsatisfyrequireddataupdatecycles.Inparticular,thedelaybecomesworseinasystemwithahighPERinameshtopologywhichusesrout-ers (see Part B).

LayingoutfieldwirelessdevicesasdescribedinthisdocumentwillhelpsuppresstheincreaseinPEReveninharshenvironments,andstabilizewirelesscommunication.

PartAexplainsthebasicwirelessconnectiontopology.PartBdescribeshowtoinstallfieldwirelessdevices.PartCshowstheevaluationprocedureinsitesurveys,andPartDandEshowexamplesofjudgingthenecessityofsite surveys.

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Part A. Layout and Topology of Wireless Devices


Toenablewidespreadusage,Yokogawa’sfieldwirelesssystemsupportstwonetworktopologies:startopologyandmeshtopology.

Thetopologyandlayoutarecloselyrelated.Thestartopologyisusedwhenthesamplingintervalislessthan5seconds.Themeshtopologyisusedforasamplingintervalof5secondsorlongerbecausetransmissionmaybedelayedduetothemulti-hopconfiguration.

Basically, devices are laid out as follows:

A1. Star topologyInthestartopology,anaccesspointcommunicateswithmultiplewirelesstransmittersdirectly.Therefore,thesedevicesortheirantennasmustbeinstalledtosecuretheline-of-sightandFresnelzone(seeReference2).InClass A and B areas (see Section B1.1), it is crucial to secure the line-of-sight.

InClassCareas,ontheotherhand,theline-of-sightmaynotmatterbecauseoftheshortwirelesscommunica-tiondistance.Themaximumcommunicationdistancecanbeextendedbyavoidingobstacleswithremoteanten-nas or by using high-gain antennas.

Figure A-1 Star topology

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A2. Mesh topologyYokogawa’sfieldwirelessnetworksupportsuptofourhopsforthemeshtopology.Themeshtopologyassuresscalabilityandconnectivitybyinstallingrouterssufficientlyhightogiveaclearline-of-sight.Themeshtopologyisused for securing redundancy or avoiding obstacles.

Asageneralrule,Yokogawa’sfieldwirelessdevicesareinstalledwithintwohopsasshowninFigureA-2.Rout-ersareinstalledhighupovertheplant.YokogawacallsthisformSkyMesh.Notethatifthenumberofhopsincreases,thedevicelayoutandinstallationdesignwillbecomecomplicated,whichlimitsthenumberofdevicesthatcanbeconnectedtotherouters.Athree-orfour-hopconfigurationshouldbeusedonlywherecommunica-tion devices are arranged in a line such as off-site of wellheads.

RoutersortheirantennasareinstalledatheightstosecuretheFresnelzonedependingonthecommunicationdistancebetweenroutersandanaccesspoint(describedlater).Thiscanreducetheinfluenceofobstaclessuchasfixedfacilitiesanddevices,aswellastheeffectofmovingobstaclessuchaslargevehiclesorcranetrucks.

(a) Sky Mesh in a plant

(b) Mesh topology for a redundant path network

Figure A-2 Mesh topology

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Part B. Guidelines for Device Layout and Installation


Therearethreeguidelinesforthelayoutoffieldwirelessdevices:communicationdistance,installationprocedure,and use of routers.

B1. Communication distanceYokogawa’sfieldwirelessdevicesconformingtotheISA100.11astandardfeaturealongcommunicationdis-tance.ThedatainthissectionarebasedonYokogawa’sfieldwirelessdevicesonly.

B1.1 Classification of communication environment and expected communication distance

Tofacilitatethelayoutandinstallationoffieldwirelessdevices,Yokogawaclassifiestheexpectedcommunicationdistanceintothreeclassesaccordingtothecommunicationenvironment.Theexpectedcommunicationdistanceismeasuredwitha2dBiantennawithallinstallationrequirementssatisfied(includingthegainofanantennawithoutputof10mW).

1. Free space (Class A): Area with no obstacles around wireless devicesExpectedcommunicationdistance:upto500m

Examples:Pipeline,tankyard

Figure B-1 Example of Class A area

2. Minor obstacles (Class B): Area with structures and obstacles which affect wireless signals through reflection, etc.Expectedcommunicationdistance:upto200m

Examples:Areaswithbuildingsormachinesaroundthecommunicationpath.Areaswithdensepipingalongthecommunicationpath.

Figure B-2 Example of Class B area

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3. Dense obstacles (Class C): Area surrounded by structures and obstacles which severely affect wireless signals.Expectedcommunicationdistance:upto50m

Examplesofarea:Insideoftheplantsurroundedbypipesandmachines

Figure B-3 Example of Class C area

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B2. Installation procedureThis section outlines the usage criteria for routers, high-gain antennas, and extension antenna cables. There are two general rules about the installation regardless of whether or not to use these devices.

l Up to two hopsAsthenumberofhopsincreases,thenumberoftransmittersconnectabletoeachrouterdecreases,whichmakesitdifficulttolayoutthesystem.

l Installation at heightsAntennasshouldbeinstalledatheightstoavoidtheinfluenceofbothfixedobstacles(buildings,etc.)andmov-ing obstacles (vehicles, etc.) in a plant.

Selectanappropriateinstallationproceduredependingontherequirementsbelow:

Communication cycle of less than 5 seconds Star topology

Mesh topologySky MeshAvoid obstacles/Extend distance

Mesh topology with three or more hopsLong-distance communication with multi-hops

Use of remote antennas

Use of high-gain antennas

Other installation procedure:Avoid small obstaclesLong-distance communication with one hop

Figure B-4 Selection of an installation procedure

B2.1 Selecting the star topologyWhenacommunicationcycleoflessthan5secondsisrequired,thestartopologyisrecommendedtobeusedforcommunicationbetweentransmittersandanaccesspoint.Evenwhenthereareobstaclesintheline-of-sight,thestartopologyensurescommunicationaslongasthecommunicationdistanceis50morshorter.Thisisbecausewirelessdevicescanreceivesignalswhicharereflectedoffthesurroundingpipingorwalls.

Figure B-5 Selecting the star topology

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B2.2 Selecting the mesh topologyl Sky Mesh in a plantAsdescribedearlier,routersatheightswithaclearline-of-sightimproveexpandabilityandconnectivity.De-vicesinstalledasshowninFigureB-6(a)coverawideareaofcommunication.Whenroutersareinstalledsoastooverlapeachother’scommunicationareaasshowninFigureB-6(b),communicationismaintainedevenifthemeasuringpointsmovewithinaspecifiedareasuchascoalstorageyards.

(a) Sky Mesh configuration

(b) Coal storage yard

Figure B-6 Example of the mesh topology

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l Avoiding obstacles and extending the communication distanceInstallingroutersinthemeshtopologyextendscommunicationbeyondtheexpectedcommunicationdistancewhile avoiding obstacles*1.RoutersandtheirantennasareinstalledsothattheFresnelzoneissecured.Use2-dBi standard antennas in consideration of their directivity angle*2. For details on installing routers, see the following section.

Figure B-7 Avoiding obstacles with the mesh topology

*1:Relativelysmallobstaclescanbeavoidedbyshiftingantennaswithextensionantennacables(upto13m)describedlater.*2: For details of the directivity angle, see Reference 2.

B2.3 Configuring the mesh topology with three or more hops

Themeshtopologyisbasicallyconstructedwithuptotwohops,butitcanbeconstructedwiththreeorfourhopswherelong-distancecommunicationisrequiredsuchaswellheadsandoffshoreplantsaslongasrouterscanbeinstalledinaline.Inthiscase,thenumberofdevicesconnectabletoroutersdecreases.Fordetails,see“G2.6.1RestrictionsontheNumberofConnectableDevicesbyNetworkResources”(IM01W02D01-01EN).

Figure B-8 Example of the mesh topology at a wellhead

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B2.4 Other installation procedures: using high-gain antennas

Withahigh-gainantenna,longercommunicationthantheexpectedcommunicationdistanceispossible.Inthiscase,theheightoftheantennaandtheFresnelzonemustbeconsideredasshowninReference1.Becausehigh-gain antennas need a clear line-of-sight, they are not used in Class B and C areas.

l Order of priority when installing high-gain antennasIfthedistancebetweenwirelessdevicesexceedsthemaximumcommunicationdistanceintherelevantclass,useahigh-gainantennaforaccesspoints.Inthiscase,sufficientheightisnecessarytosecuretheFresnelzone.Fordetails,seeReference1.

l Antenna height of the target deviceWhenahigh-gainantennaisused,theantennaheightofthetargetdevicemustbeconsidered.Theantennaofthetargetdevicemustbewithintheradiationangleofthehigh-gainantenna.

Table B-3 shows the allowance of the antenna position of the target device (difference in height between the originating antenna and the destination antenna) when using a 6 dBi antenna as the originating antenna. In this case,theallowanceisaboutone-fifththecommunicationdistance.

Communication distance

Allowable difference in heights

Figure B-10 Relationship between the communication distance and antenna height

Table B-3 Correlation between communication distance and allowable antenna height

Communication distance (m)

Allowable antenna height [m]

10 2

50 10

100 20

200 40

500 100

800 156

*Notethatthereisnoneedtoconsidertheallowableantennaheightinlong-distancecommunication.Foracommunicationdistanceof100morlonger,adifferencebetweenantennaheightsof20mormoreisallowable.Thisguidelineappliestocaseswhereantennaheightsareextremelydifferentfromeachother..

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B2.5 Other installation procedures: using extension antenna cables

Tosetupcommunicationfrominsideabuildingtotheoutsideortoavoidsmallobstacles,usea3mor13mextension antenna cable. Extension cables are often a useful way to secure an excellent line-of-sight.

(a) Installing an antenna outside the building (b) Securing the Fresnel zone

Figure B-11 Using an extension antenna cable

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B3. Using routersFollow the guidelines below when installing routers.

l Installingrouterssothatalltransmittershavetwocommunicationpaths.

l Install routers as high as possible.

l Usea2dBiantennaforrouterswhichcoverI/Odeviceslocatedbelow.

B3.1 Installing routers so that all transmitters have two communication paths

Ifthereisonlyonecommunicationpathandtherouterbatteryneedstobechangedoracommunicationfailurehappens,thedatafromtransmitterswillbelost.Installingrouterstosecureatleasttwocommunicationpathscansignificantlyreducetheriskofdataloss.

B3.2 Installing routers as high as possibleTosecurecommunicationqualitybetweentherouterandanaccesspoint,installroutersashighaspossiblewithaclearline-of-sighttotheaccesspoint.Thisminimizesdisturbancescausedbyvehiclesandhumansandmakescommunicationmorereliable.

B3.3 Using a 2 dBi antenna for routersUsea2dBiantennaforrouterswhichcoverI/Odeviceslocatedbelow.Thisisbecause2dBiantennashaveawidedirectivityangleandareidealforverticalcommunication(seeReference2).Withagoodline-of-sight,2dBiantennascancommunicatewiththetargetdeviceoveradistanceofupto30mevenifitislocatedoutoftheradiation angle.

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B3.4 Examples of router installationInstallrouterssothatareliablecommunicationpathwithfewobstaclesissecured.

(1) Secure a communication path above obstacles between the access point and the router.

Figure B-12

(2) Secure vertical communication paths among the router and transmitters.

Figure B-13

(3) A poor line-of-sight does not affect communication between the router and transmitters as long as the communication distance is 50 m or shorter.

Figure B-14

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Part C. Guidelines for Device Layout and Installation

Part C. Guidelines for Implementing the Site Survey

Thissectionandthefollowingsectionsdescribethetypesofdevicelayout.Alayoutwithvisualassessmentaloneand another one which needs a site survey are illustrated.

Visualassessmentisnecessaryforconfirminghowtomounttransmitters,howtofeedpowertotheaccesspoint,andhowtoconnecttheuppersystem,andisalmostthesameasthatforwiredtransmitters.Whendesigningafieldwirelessnetwork,thefollowingadditionalinformationisneeded:asitemap,layoutofotherdevices,andad-ditionalinformationtojudgeapplicabilitytothedesigntypesdescribedbelow.

If the feasibility of installation is still not clear, carry out a site survey.

C1. Installation design with a site plan/device layout only (visual assessment and site survey are not required)

Thisdesignisapplicablewhenthefollowingconditionsareconfirmedwiththesiteplan:

Outdoorinstallation,topologywithuptotwohops,goodline-of-sight,andsufficientheightofantennassecuringtheFresnelzonewithnoobstacles

C2. Installation design with a site plan/device layout and visual assessment (site survey is not required)

Whenthedesignfollowstheinstallationguidelinesandtherearenoother2.4GHznetworks(e.g.,Wi-Fi),sitesurveyscanbeomitted.

Thefollowingtwocasesdonotrequireasitesurvey:

1.Wirelessdevicesarefixedinaroomwithanareaof50msquareorsmaller.Wirelessdevicescanbemountedonrotatingobjectsbutnotonmovingobjects.

2.Wirelessdevicesaremountedinaspacewithametalgratingfloor,butthecommunicationdistanceis50morshorter.

C3. Installation design requiring a site surveyIfthefeasibilityofinstallationisstillnotclearafterthevisualassessmentandinstallationdesign,carryoutasitesurvey.

The following cases clearly need site surveys:

1.Communicationbetweenindoorsandoutdoors.Atleastonewirelessdeviceislocatedinashieldedenclosuresuchasabasementorprefabricatedbuilding.

2.Wirelessdevicesaremountedonmovingobjects.

3.Thereisanother2.4GHznetwork(e.g.,Wi-Fi)nearthecommunicationpath.

4.Therearenoisesourcesnearthecommunicationpath(e.g.,militarycommunicationfacilitiesandradarswithhigh output power).

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Part C. Guidelines for Device Layout and Installation

START

A site survey is required.

Visual assessment

Installation design

Another 2.4 GHz wireless communication exists.

All installation guidelines are followed.

END

Yes

No

No

Yes

No

Yes

Yes

Yes

No

Falls in any of the cases in C3.

Falls in either of the two cases in C2.

Figure C-1 Flow chart for judging the necessity of site surveys

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Part D. Examples of Installation Design without Site Survey

Part D. Examples of Installation Design Not Requiring Site Surveys

D1. Installation guidelines are followed

Figure D-1 Example of a layout following the guidelines

D2. Devices are mounted on rotating objectsTheline-of-sightfromtransmittersmountedonrotatingobjectstoanaccesspointisperiodicallydisturbedbytheobjects.However,communicationcancontinuethankstoreflectedsignals.Theareaoftheinstallationsite,mate-rialofthewalls,andotherpossibleobstaclesatthesitemustbesurveyed.

Figure D-2 Example of mounting on a rotating object (1)

Figure D-3 Example of mounting on a rotating object (2)

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Part D. Examples of Installation Design without Site Survey

D3. Devices are installed in a small space (50 m square or smaller)

Evenwithapoorline-of-sightorobstaclesincludingmetalgratingfloors,transmitterscanmaintaincommunica-tionaslongasthecommunicationdistanceis50morshorter.

Well

5 m

20 m

I/O

AP

AP

15 m

Metal grating floor

Cimney pipe

15 m

AisleI/O

I/O

Figure D-4 Example of installation with obstacles and metal grating floors

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Part E. Examples Which Clearly Require Site Survey

Part E. Examples Clearly Requiring Site Surveys

E1. Installation in a place surrounded by metal walls

Asitesurveyisrequiredbeforeinstallingtransmittersinaplacesurroundedbymetalwalls.Possibleroutesofcommunicationshouldbeexploredinthesitesurveybecausewirelesssignalscannotpassthroughmetalwalls.Wirelesssignalscancommunicatethroughnon-metalwalls,althoughthesignalswillbeattenuatedtosomeextent.

Figure E-1 Space surrounded by metal or concrete walls

Figure E-2 A transmitter surrounded by metal walls

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Part E. Examples Clearly Requiring Site Surveys

Figure E-3 A transmitter surrounded by concrete walls

(a) Installation in a pipe rack (b) Installation in a tunnel

Figure E-4 Small installation area in which it is difficult to secure the Fresnel zone

E2. Wi-Fi communication close to the field wireless system

PleasecontactthenearestYokogawasalesofficeorYokogawarepresentative.

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Referense

Reference 1: Fresnel ZoneForreliablewirelesscommunication,itisimportantnotonlytosecuretheline-of-sightbutalsotoensurethattherearenoobstaclesinthesurroundingspace.ThisspaceiscalledtheFresnelzoneandislargestatthemid-pointofthecommunicationdistance.TheradiusoftheFresnelzonedependsonthecommunicationdistance.

The largest radius of the Fresnel zone

I/O or RT

The largest radius of the Fresnel zone

(m)Distance

(m)

Ifthereareanyobstacleswithinthezone,thecommunicationdistancebecomesshorter.Thegroundisalsoapossible obstacle. Therefore, when installing wireless devices, the effect of the ground can be expected even if therearenoobstaclesbetweenthem.Referringtothetableabove,wirelessdevicesmustbemountedhigherthanthelargestradiusoftheFresnelzone.

Maximum communication distance with an intact Fresnel zoneInordertoestimateacommunicationdistanceforeachpath,theexpectedcommunicationdistanceinrespectiveenvironmentalclassifications(A,B,C)andobstaclesintheFresnelzone(seeReference1)mustbeconsidered.Thetablebelowshowstheexpectedcommunicationdistanceinconsiderationofthefactors.

Table Communication distance depending on factors

Combination of antennas

Antenna height (m)

Maximum communication distanceClass A (500 m) Class B (200 m) Class C (50 m)

2 dBi - 2 dBi

4.0 500 250

503.1 300 150

1.8 100 50

0.5 ----- 50

2 dBi - 6 dBi

5.5 1000 ----- -----

5.0 800 ----- -----

4.5 600 ----- -----

6 dBi - 6 dBi

7.5 1500 ----- -----

6.5 1250 ----- -----

5.5 1000 ----- -----

Evenifaline-of-sightcannotbesecured,goodcommunicationisexpectedinaClassCareaaslongassignalscanreflectoffsurroundingstructures(unlessthewirelessdevicesareenclosedbymetalwalls).Fordetails,seeB2.

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Referense

Figure Antenna height necessary for 500 m and 1000 m communication

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Referense

Reference 2: Requirements for Antenna InstallationTosatisfythecommunicationdistancespecification,antennasmustbeinstalledincompliancewiththefollowingconditions.Otherwise,communicationdistancesmaybecomeshorter.

A.Fieldwirelessdevicesmustbemountedwherenoobstaclesexistneartheirantenna.

B.Antennasmustbeinstalledvertically.

C.Antennasmustbeatleast30cm*awayfrommountingpipingorplumbing.

D.Iftheinstallationlocationistooclosetowalls,usearemoteantennaandextensionantennacabletopreventobstaclesfromaffectingwirelesssignals.

E.InClassAandBareas,installfieldwirelessdevicessothateachhasagoodline-of-sighttootherantennasinthecommunicationarea.Usearemoteantennaandextensionantennacable,ifnecessary.Thisisnotes-sentialinaClassCareabecauseitisdifficulttosecureagoodline-of-sightonlywithextensionantennacablesin such an area.

F.Whendevicesareinstalledatdifferentheights,overlaptheircommunicationrangesinconsiderationofthera-diationcharacteristicsofrespectiveantennas.Thus,forexample,standard2dBiantennascanemitsignalsupto45degreesupordownfromthehorizontalplane.Meanwhile,6dBiantennasemitonlywithin±11degrees.So,6dBiantennasarenotappropriateforverticalcommunication.

*When 2 dBi antennas are used in a Class C area(When2dBiantennasareusedinClassAorBareas,antennasmustbeatleast1mawayfrommountingpipingorplumbing.)

Radio propagation area(standard antenna)

L max

Vertical range

Antenna

45°

45°

Horizontal range1.5 m or

higher

30 cm or more

Requirements for mounting

2B piping mounting

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Referense

Reference 3: Packet Error Rate (PER)Thepacketerrorrate(PER)isagoodindicatortojudgethereliabilityofcommunicationpaths.ThePERequationis as follows:

PER(%)=Numberoflostpackets/Numberoftransmittedpackets×100

Packetsareconsideredaslostwhenan“acknowledge”packetfromthetargetdeviceisnotreceivedorwhena“noacknowledge”packetfromthetargetdeviceisreceived.

Yokogawa’sfieldwirelesssystemre-sendspacketswhenitdetectspacketloss.WithalowPER,devicescansuccessfully send all data with fewer retries.

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