USS4tip.docx

USS4tip.docx

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USS4tip

UsingUSS4ProtocolInstructionsto

CommunicatewithDrives

VERSION:

1.1

DATE:

07/2001

ThistipdescribestheUSS4ProtocolinstructionsthatallowtheS7–200tocontrolaMicroMasterdrive（MM3andMM4）.

Withthesenewinstructions,youcancontrolthephysicaldriveandreadandwritedriveparameters

ChapterOverview

Section

Description

Page

1.1

USS4ProtocolInstructionRequirements

2

1.2

ProgrammingSequence

4

1.3

USS4ProtocolInstructions

5

1.4

ConnectingMM3Drives

19

1.5

ConnectingMM4Drives

20

1.6

MM3DriveSetup

22

1.7

MM4DriveSetup

24

ThisTipdoesnotpurporttocoveralldetailsorvariationsinequipment,nordoesitprovideforeverypossiblecontingency.Yourapplicationmaybedifferentfromthosecontemplatedherein.ItisyourresponsibilitytousetheSIMATICS7-200properlyinyourapplication.ThisTipdoesnotrelieveyouoftheresponsibilitytousesoundpracticesinapplication,installation,operationandmaintenance.ByusingthisTip,youacknowledgethatSiemensshallnotbeliableunderanytheoryfordamagesorpersonalinjuryresultingfromsuchuse.

SiemensreservestherighttomakechangesinthisTipatanytimewithoutnoticeorobligation.ShouldaconflictarisebetweenthesuggestionsinthisTipandotherSiemenspublicationssuchastheS7-200ProgrammableControllerSystemManualortheSIMATICS7/M7/C7ProgrammableControllersCatalogST70,theotherpublicationshalltakeprecedence.

Copyright©2001SiemensEnergy&Automation,Inc.AnyformofduplicationordistributionoftheseTipsorexcerptshereofisprohibitedwithouttheexpressconsentofSiemensEnergy&Automation,Inc.

1.1USS4ProtocolInstructionRequirements

TheUSS4ProtocolinstructionsrequirethefollowingresourcesfromyourCPU:

∙Size3000bytes

∙Port0（only）

∙14subroutinesand3interrupts

∙Vmemorysize400bytesanda16–bytebufferforsomeinstructions

ResourceUsage

USS4ProtocolInstructionusesresourcesasshownbelow:

∙Port0:

WhenPort0isbeingusedforUSS4Protocolcommunications,itcannotbeusedforanyotherpurpose,includingcommunicatingwithSTEP 7-Micro/WIN.TheUSS4_INITinstructioncontrolsassignmentofPort0toUSS4ProtocolorPPI.OncePort0hasbeenassignedtoUSS4usage,Port0canonlybeusedagainforSTEP7-Micro/WINcommunicationbyaprogrammedreassignmentviaanotherUSS4_INITinstruction,orbysettingtheMODEswitchtoSTOP.Stoppingcommunicationtothedriveswillcausethedrivestostop.ItisrecommendedthatduringprogramdevelopmentofUSS4Protocolapplications,thedevelopershoulduseaCPU226,orEM277PROFIBUS-DPinconjunctionwithaPROFIBUSCPcardinthePC.ThisallowsasecondcommunicationsporttobeusedforSTEP7-Micro/WINmonitoringoftheapplicationwhileUSS4Protocolisrunning.

∙AllSMlocationsassociatedwithFreeportcommunicationonPort0willbeaffectedbyUSS4protocolinstructions.

∙Userprogramspace:

Inadditiontothespaceoccupiedbyeachinstruction,thereisauserprogramspaceoverheadofupto3000bytesoccupiedbyUSS4protocolsupportroutines

∙Vmemory:

A400byteblockofVmemory,startingatVB4723,isreservedforUSS4variables.A16–bytecommunicationsbuffer,startingatauserassignedlocation,isrequiredforsomeinstructions.ItisrecommendedthatauniquebufferbeassignedforeachinstanceofUSS4protocolinstructions.

∙14subroutinesand3interruptsaretakenbyUSS4protocol.

DriveCommunicationsTime

CommunicationwiththedriveisasynchronoustotheCPUscan.SeveralCPUscanswillusuallycompletewhileonedrivecommunicationtransactioncompletes.Thisdependsonthenumberofdrivespresent,thebaudrate,andthescantimeoftheCPU.Table1–1showscommunicationstransactiontimes.OnceaUSS4_INITinstructionassignsPort0toUSS4Protocol,theCPUregularlypollsallactivedrivesattheintervalsshowninTable1–1.Thetimeoutparameterofeachdrivemustbesettoallowforthispolltime.

Table1–1DriveCommunicationsTimes

BaudRate

TimeBetweenPolls

totheActiveDrives（ms）

1200

（400maximum）*numberofdrives

2400

（200maximum）*numberofdrives

4800

（110maximum）*numberofdrives

9600

（70maximum）*numberofdrives

19200

（50maximum）*numberofdrives

38400

（40maximum）*numberofdrives

Restriction

OnlyoneUSS4_RPM_xorUSS4_WPM_xinstructioncanbeactiveatatime.TheDoneoutputofeachinstructionshouldsignalcompletionbeforeuserlogicinitiatesanewinstruction.UseonlyoneUSS4_DRV_CTRLinstructionforeachdrive.

1.2ProgrammingSequence

TheprogrammingsequenceforusingUSS4Protocolinstructionsisshownbelow.

1.PlacetheUSS4_INITinstructionintheuserprogram.TheUSS4_INITshouldonlybecalledforonescantoinitiateorchangetheUSS4communicationparameters.Seepage1–5formoreinformationabouttheUSS4_INITinstruction.

2.PlaceonlyoneUSS4_DRV_CTRLinstructionperactivedriveinyourprogram.YoumayaddasmanyUSS4_RPM_xandUSS4_WPM_xinstructionsasyouwish,butonlyoneofthesemaybeactiveatatime.

3.Configurethedriveparameterstomatchthebaudrateandaddressusedintheprogram.RefertotheDriveSetupinSection1.5.

4.ConnectthecommunicationscablebetweentheCPUandthedrives.Itisveryimportantthatanycontrolequipmentthatisconnectedtothedrive（suchasaPLC）isconnectedtothesamegroundorstarpointasthedrivebyusingashort,thickcable.

Caution

Interconnectingequipmentwithdifferentreferencepotentialscancauseunwantedcurrentstoflowthroughtheinterconnectingcable.

Theseunwantedcurrentscancausecommunicationerrorsorcandamageequipment.

Besureallequipmentthatyouareabouttoconnectwithacommunicationcableeithersharesacommoncircuitreferenceorisisolatedtopreventunwantedcurrentflows.SeethesectiononGroundingandCircuitReferencePointforUsingIsolatedCircuitsintheSIMATICS7-200ProgrammableControllerSystemManualformoreinformation.

Theshieldmustbetiedtoachassisgroundorterminal1onthe9-pinconnector.Itisrecommendedthatyoutieterminal20VontheMicroMasterdrivetochassisground.

_____________________________________________________________________________

Note

IfyoucannotreadallthevariablesontheUSSinstructionblocks,selectView>Zoomfromthemenuandthenincreasethegridwidth.

_____________________________________________________________________________

1.3USS4ProtocolInstructions

USS4_INIT

TheUSS4_INITinstructionisusedtoenableandinitialize,ortodisableMicroMasterDrivecommunication.BeforeanyotherUSS4Protocolinstructioncanbeused,theUSS4_INITinstructionmustbeexecutedwithouterrorsbeingreturned.TheinstructioncompletesandtheDonebitissetimmediately,beforecontinuingtothenextinstruction.

TheinstructionisexecutedoneachscanwhentheENinputison.TheUSS4_INITinstructionshouldbeexecutedexactlyonceforeachchangeincommunicationstate.Therefore,theENinputshouldbepulsedonthroughanedgedetectionelement.OnceUSS4Protocolhasbeeninitiated,itmustbedisabledbyexecutionofanewUSS4_INITinstructionbeforeachangeininitializationparameterscanbemade.

ThevaluefortheUSSinputselectsthecommunicationprotocol.1assignsport0toUSSprotocolandenablestheprotocol.0assignsport0toPPIanddisablestheUSSprotocol.

BAUDsetsthebaudrateat1200,2400,4800,9600,19,200,or38,400.

ACTIVEindicateswhichdrivesareactive.Somedrivesonlysupportaddresses0through30.Figure1–1showsthedescriptionandformatoftheactivedriveinput.AnydrivethatismarkedasACTIVEisautomaticallypolledinthebackgroundtocontrolthedrive,collectstatus,andpreventseriallinktimeoutsinthedrive.RefertoTable1–1onpage1–3tocomputethetimebetweenstatuspolls.RefertoSection1.5forinformationabouthowtoconfiguretheseriallinktimeoutparameter.

Figure1-1ActiveDriveDescriptionandFormat

WhentheUSS4_INITinstructioncompletes,theDONEoutputisturnedon.TheERRoutputbytecontainstheresultofexecutingtheinstruction.Table1–10onpage1–16definesthepossibleerrorconditionsthatmayresultfromexecutingtheinstruction.

Table 1–2showstheoperandsanddatatypesoftheUSS4subroutines.

Table1-2OperandsandDataTypesfortheUSS4_INITSubroutine

Inputs/Outputs

Operands

DataTypes

USS

VB,IB,QB,MB,SB,SMB,LB,AC,Constant,*VD,*AC,*LD

BYTE

BAUD

VW,IW,QW,MW,SW,SMW,LW,T,C,AIW,Constant,AC*VD,*AC,*LD

WORD

ACTIVE

VD,ID,QD,MD,SD,SMD,LD,AC,Constant,*VD,*AC,*LD

DWORD

DONE

I,Q,M,S,SM,T,C,V,L

BOOL

ERR

VB,IB,QB,MB,SB,SMB,LB,AC,*VD,*AC,*LD

BYTE

USS4_DRV_CTRL

TheUSS4_DRV_CTRLinstructionisusedtocontrolanACTIVEMicroMasterDrive.TheUSS4_DRV_CTRLinstructionplacestheselectedcommandsinacommunicationbuffer.Commandsinthebufferaresenttotheaddresseddrive（DRIVEparameter）,ifthatdrivehasbeenselectedintheACTIVEparameteroftheUSS4_INITinstruction.EachdriveshouldhaveonlyoneUSS4_DRV_CTRLinstruction.

TheENbitmustbeontoenabletheUSS4_DRV_CTRLinstruction.Typically,thisinstructionisalwaysenabled.

RUN（RUN/STOP）indicateswhetherthedriveison

（1）oroff（0）.WhentheRUNbitison,theMicroMasterDrivereceivesacommandtostartrunningatthespecifiedspeedanddirection.Inorderforthedrivetorun,thefollowingmustbetrue:

∙DRIVEmustbeselectedasACTIVEinUSS4_INIT.

∙OFF2andOFF3mustbesetto0.

∙FAULTandINHIBITmustbe0.

WhenRUNisoff,acommandissenttotheMicroMasterDrivetorampthespeeddownuntilthemotorcomestoastop.

TheOFF