User Manual

6
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AUTOMATION & PROCESS
TECHNOLOGIES
Variable Pulse (PWM)
Thevariablepulsesignalinterfaceisapulse
widthmodulatedsignal(RS422).Themaximum
cablelengthforthedifferentialLDTis1,500feet.
TheLDTcanalsobeconguredforexternalor
internalinterrogation.Externalinterrogatingis
whenanexternaldeviceconnectedtotheLDT
generatesastartpulse.Thisstartpulseshouldbe
aminimumof1.0microsecondinduration.Within
50nanosecondsaftertheleadingedgeofthestart
pulsehasbeenreceived,theLDTwillgenerate
anoutputpulse.Thedurationoftheoutputpulse
isproportionaltothedistancefromthemagnet
tothehexhead.Theorderofthesetwopulses
isillustratedbelow.TheLDTcanalsogenerate
internalinterrogations.ThisLDTwillcontinually
outputpulsewidthmodulatedsignals.Aswithan
LDTusinganexternalinterrogation,thedurationof
thisoutputpulseisproportionaltothedistancefrom
themagnettothehexhead.
OUTPUTPULSE
LOWOUTPUTVARIESDEPENDINGONLENGTH
PROGRAMMEDVIADIPSW2SWITCHES1-6
WIDTHOFPULSEISPROPORTIONAL
TODISTANCEBETWEENMAGNETANDHEXHEAD
INTERNAL INTERROGATION
INPUT(INTERROGATION)
1MICROSECOND(RECOMMENDED)
0.2MICROSECONDS(MINIMUM)
WIDTHOFPULSEISPROPORTIONALTO
DISTANCEBETWEENMAGNETANDHEXHEAD
OUTPUTPULSE
WITHIN50NANOSECONDSAFTERINTERROGATION
TODISTANCEBETWEENMAGNETANDHEXHEAD
EXTERNAL INTERROGATION
RS422 Start/Stop with
Interrogation Start Sequence
Thestart/stopusesa1microsecond(minimum)
externalinterrogationinputtostartacycle.Based
ontheinterogationinput,apairofonemicrosecond
returnpulsesarereceivedandthetimedifferential
betweenthesignalsisproportionaltothedistance
fromthesensorhead(hex)andmagnet.
TTL Level Start/Stop Version
TheTTLLevelstart/stoppulsesystemlooksata
onemicrosecondTTLpulse(minimum)startpulse
fromanexternalsource.Theunitwillthengenerate
aTTLlevelstoppulse.Thetimespanbetweenthe
start/stoppulsesisproportionaltothedistancefrom
thesensorhead(hex)tothemagnet.
INPUT(INTERROGATIONPULSE)
1MICROSECOND(RECOMMENDED)
0.2MICROSECONDS(MINIMUM)
TIMEBETWEENPULSESISPROPORTIONALTO
DISTANCEBETWEENMAGNETANDHEXHEAD
OUTPUT(STARTPULSE)
OUTPUT(STOPPULSE)
WITHIN2.0MICROSECONDSAFTERINTERROGATION
PULSEBEGINS,STARTPULSEBEGINS
INPUT(INTERROGATIONPULSE)
1MICROSECOND(RECOMMENDED)
0.2MICROSECONDS(MINIMUM)
TIMEBETWEENPULSESISPROPORTIONALTO
DISTANCEBETWEENMAGNETANDHEXHEAD
OUTPUT(STARTPULSE)
OUTPUT(STOPPULSE)
WITHIN2.0MICROSECONDSAFTERINTERROGATION
PULSEBEGINS,STARTPULSEBEGINS
Output Types