User manual


 DocumentMT0100P.N
©XsensTechnologiesB.V. MTiandMTxUserManualandTechnicalDocumentation

32
5.5 Triggering&synchronization
In case multiple systems are used during a measurement it is important to have the measurement data
synchronizedbetweenthesystems.Processingsynchroniseddataismucheasierbecausethereisnoneedto
resamplethedatatocompensatefortiminginaccuracieslikeclockdriftandclockdeviations.Synchronization
usingmultiplesystemsinvolves2importantissues:startingthemeasurementatthesametimeandhavinga
fixedtimerelationshipofthesamplinginstances.ThissectionwillexplainhowtheMTi/MTxmustbesetup
whenusingmultiplemeasurementsystems.
The MTi / MTx have capabilities to be triggered by external devices or trigger external devices. These two
scenariosareexplainedinthefollowingsubsections.
5.5.1 ExternaldevicetriggersMTi/MTx
In the following figure, a possible configuration is shown where a Motion Tracker and Device A are
synchronised. In this example, a clock generator triggers device A and a MTi / MTx ensuring that the two
devicesaresynchronizedwitheachother.

TheoutputoftheclockgeneratorcanbedirectlyconnectedtotheMTi/MTxortothespareheaderofthe
USBconverterasshowninthefigureabove.Moreinformationaboutthiscanbefoundinsection6.4.1.

NOTE:AlwayscheckiftheSyncInspecificationmatcheswiththetriggersignal.Seesection6.4.

The following MTi / MTx devicessupport SyncIn, MTi‐28A##G## (MTi RS‐232), MTi‐48A##G## (MTi RS‐485),
MTi‐68A##G##(MTiRS‐422)andMTx‐28A##G##(MTxRS‐232).

TheSyncInsignalcaneithertriggerthetransmissionofthelatestdataortheinternalsensorsampling.Thefirst
SyncInmodeishighlyrecommendedinsituationswheretheclocksignalisnotreliableand/oraccurate.More
informationisgiveninthenexttwosections.FormoreinformationabouttheSyncInmodesandsettingssee
MTiandMTxLow‐LevelCommunicationDocument.

Transmissionofthelatestdata
InthisSyncInmodetheinternalclockand thestoredsamplefrequencydeterminewhenthesamplingofthe
sensorsignalsstart.ThedataistransmittedonlyifatriggerisdetectedontheSyncInline.Thismeansthatthe
triggerinstance will not coincide with the sampling instanceof the transmitted data. Because twodifferent
clocks are used the time difference between the trigger instance and the sampling instance may also vary
duringthemeasurementandatmostwithatimeequaltotheusedsamplingperiod.Neverthelessthismodeis
preferred if the clock generatoris not that accurate as the internal clock of the MTi /  MTx. In this mode a
SyncIntriggerwillalwaystransmitthelatestdataavailable.

MT
USB
Converter
Device A
S
y
ncIn
Clock
generator
Trigger in