Campbell CR850 - Page 442

Section 11. Glossary
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(86,400seconds),itissynchronizedwiththe24‐hourclock,sothatthe
programisexecutedatmidnightandeveryScan()Intervalthereafter.
Theprogramisexecutedforthefirsttimeatthefirstoccurrenceofthe
Scan()Intervalaftercompilation.IftheScan()Intervaldoesnotdivide
evenlyinto24hours,executionwillstartonthefirstevensecondafter
compilation.
scantime
WhentimefunctionsareruninsidetheScan()/NextScanconstruct,
timestampsarebasedonwhenthescanwasstartedaccordingtothe
CR800clock.Resolutionofscantimeisequaltothelengthofthescan.
Seesystemtime
(p.445).
SDI‐12
SerialDataInterfaceat1200bps.Communicationprotocolfor
transferringdatabetweendatarecordersandsensors.
SDM
Synchronousdeviceformeasurement.Aprocessor‐basedperipheral
deviceorsensorthatcommunicateswiththeCR800viahardwireovera
shortdistanceusingaproprietaryprotocol.
SeebeckEffect
Inducesmicro‐Voltlevelthermalelectromotiveforces(EMF)across
junctionsofdissimilarmetalsinthepresenceoftemperaturegradients.
Thisistheprinciplebehindthermocoupletemperaturemeasurement.It
alsocausessmall,correctablevoltageoffsetsinCR800measurement
circuitry.
Semaphore(MeasurementSemaphore)
Insequentialmode,whenthemainscanexecutes,itlockstheresources
associatedwithmeasurements,i.e.,itacquiresthemeasurement
semaphore.Thisisatthescanlevel,soallsubscanswithinthescan
(whethertheymakemeasurementsornot),willlockoutmeasurements
fromslowsequences(includingthesy
stembackgroundcalibration).
Lockingmeasurementresourcesatthescanlevelgivesnon‐interrupted
measurementexecutionofthemainscan.
Send
TheSendbuttonindataloggersupportsoftware
(p.76).TheSend
commandsendsaCRBasicprogram,oranoperatingsystem,toaCR800.