User Manual

7
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AUTOMATION & PROCESS
TECHNOLOGIES
Quadrature Output
Anewmethodofinterfacingmagnetostrictive
transducersoffersaninterfaceascommonas
analogwiththespeedandaccuracyofadigital
pulsedtypesignaling.TheGemcoquadrature
LDTsprovidequadratureoutputdirectlyfromthe
transducertothecontroller.Theoutputfromthe
transducercanbewireddirectlytoanyincremental
encoderinputorcountercard,withouttheneedfor
aspecialconvertermoduleorPLCinterfacecard
designedspecicallyforusewithpulsedoutput
magnetostrictivetransducers.Thequadratureoutput
hasthe“A”,“B”and“Z”outputs.Theseoutputs
are“differential”(alsoknownasbalanced),which
meansthattheconnectionforeachoutputconsists
oftwosignalwires.Thesearetypicallydescribed
asthe“plus”and“minus”signals.Forexample,the
“A”channelconsistsof“A+”and“A-”.Thesame
appliestothe“B”and“Z”channels.Forthese
(differential)outputs,thesignalismeasuredwiththe
referencetotheothersignal(i.e.thedifferenceor
differential).Forexample,ifthe“A+”singlevoltage
isgreaterthanthe“A-”signal,channel“A”isalogic
“0”.Again,thisappliestothe“B”and“Z”channels
aswell.Differentialtypesignalsaremuchless
pronetointerferencecausedbyelectricalnoise
orgroundloopsmoreoftenfoundinsingleended
signalconnections.Linedriversarealsoavailable
fordrivingsingleendedinputsthatarenotTTL
compatible.
SSI (Synchronous Serial Interface)
Displacementvalueisencodedintoa24,25or
26Bitformatandtransmittedathighspeeds.
Synchronizationinaclosedloopsystemismade
easy.Aclockpulsetrainfromacontrollerisused
togateoutsensordata:onebitofpositiondatais
transmittedtothecontrollerperoneclockpulse
receivedbythesensor.Theabsolutepositiondata
iscontinuallyupdatedbythesensorandconverted
bytheshiftregisterintoserialinformation.The
sensorsfulllallrequirementstotheSSIstandard
forabsoluteencoders.
SSI Clock (+)
SSI Clock (-)
SSI Data (+)
SSI Data (-)
+7 to 30 V
0V
Input
Power
Supply
SSI Shift Register and Controller
Output Data Format Conversion
Position Measurement
SSI Clock (+)
SSI Clock (-)
4.7KΩ
470Ω
4.7KΩ
12V 12V
10Ω
10Ω
SSI Data (+)
SSI Data (-)
12V 12V
10Ω
10Ω
Power Supply (+)
Common
33V
Input
Power
Supply
Ferrite
Filter
+5V
RS-422
RS-422
SSI Logic Diagram
SSI Sensor Input
SSI Timing Diagram
Clock (+)
Data (+)
Clock Interval
LSBMSB
Min. 16 µs
+A
- A
+B
- B
+Z
- Z
Output Types