Data Sheet

USBProtocolSuiteUserManual 543
StartingTrafficGeneration TeledyneLeCroyCorporation
11.8.1 Traffic Generation Modes: Bitstream vs. Intelliframe
IntelliFrameandBitstreamaremodesthatcontrolhowthegeneratorinteractswith
otherdeviceswhenitisgeneratingtraffic.
 BitstreamMode‐InBitstreamMode,thegeneratorconstructsabitstreamof
trafficbasedontheUTGfileandassumesthatpacketsstartatpre‐calculated
times.Forexample,afteranINpacket,thegeneratorwaitsacalculatedfixed
timebeforepresentinganACK.Thetimebetweenthemisdeterminedbythe
idle=timestatementinbetweentheINandACKpacketsinthe.utgfile.Inthis
mode,everybittimeofagenerationstream(includingidlesandSE0's)isrepre‐
sentedby4bitsofdata,sothefiletobedownloadedtotheGeneratorcanbe
verylarge.
 IntelliFrameMode‐InIntelliFramemode,thegeneratorcanwaitforDevice
responsestocompletebeforeitcontinuesgeneratingmorehostpackets.For
example,afterissuinganIN,thegeneratorlooksfortheDATAxpacketissuedby
thedevicetofinish,andthenissuesanACK.Thisway,thedatalengthcanvary
anddoesnotneedtobepre‐calculated.Also,usingtheidle=TO_EOFstatement
allowsthegeneratortocalculatewheretheendoftheframeoccurs,sothata
subsequentframe=AUTOstatementcreatesaStartofFrameatthecorrect
time.Moreover,theGeneratorcanbemadetoretrytransactionsthatare
NAK'edautomatically,andtousethePINGprotocolwhereappropriate.Retries
canbemadetooccurwithinthesameframeorinthenextframe.Forfurther
informationontheflexiblebehaviorthatcanbeinstitutedduringthegenera‐
tion,seethesyntaxdescriptionsforthegenerationfileshere.Anadditional
advantageoftheIntelliFramemodeisthatitcreatesanimageintheGenerator's
memorythatisMUCHsmallerthanthatoftheBitstreammode,soitdownloads
muchfaster.
Note:DeviceemulationonlyworksinIntelliframemode.
Note:InIntelliFramemode,thehardwaregeneratesSOFsandPings,sothesecannotbealtered(force
CRCvalue,explicitframenumber,andsoon).Ifyouwanttoexplicitlycorruptormanagethese
PIDtypes,youmustuseBitstreammode.
11.9 Starting Traffic Generation
Tostarttrafficgeneration,click ontheToolBar.Thisfirstparsesthe.utgfileand
downloadstheresultingbinarygenerationfiletotheVoyager.Sincethememoryis
limited,italsocheckstoseeifgeneratormemoryspaceiswastedbyexcessivenumbers
ofemptyframes,wherenotrafficoccursbetweenStart‐Of‐Framepackets.Ifthisisfound,
adialogwillnotifyyouofitsoyoucaneditthe.utgfileandfixit.See"empty_frames"key
explanationlaterinthischapter.SeeTable11.3 onpage 560.