Measurement Tutorial, DC Voltage Measurements | HP WaterSkis E1412A

Chapter 2

HP E1312A/E1412A Multimeter Application Information

Using This Chapter

This chapter provides multimeter application information in five parts.

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Measurement Tutorial.

Measurement Configuration.

Math Operations.

Triggering the Multimeter.

HP E1312A and HP E1412A Multimeter Application Examples.

Measurement Tutorial

The HP E1312A and HP E1412A are capable of making highly accurate measurements. In order to achieve the greatest accuracy, you must take the necessary steps to eliminate potential measurement errors. This section describes common errors found in measurements and gives suggestions to help you avoid these errors.

DC Voltage Measurements

Thermal EMF Errors

Thermoelectric voltages are the most common source of error in low-level dc voltage measurements. Thermoelectric voltages are generated when you make circuit connections using dissimilar metals at different temperatures. Each metal-to-metal junction forms a thermocouple, which generates a voltage proportional to the junction temperature. You should take the necessary precautions to minimize thermocouple voltages and temperature variations in low-level voltage measurements. The best connections are formed using copper-to-copper crimped connections. Table 2-1 shows common thermoelectric voltages for connections between dissimilar metals.

Chapter 2

HP E1312A/E1412A Multimeter Application Information 25

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HP WaterSkis E1412A, WaterSkis E1312A manual Measurement Tutorial, DC Voltage Measurements, Thermal EMF Errors

Contents

Contents Frequency and Period Measurement Errors Zeroauto ZEROAUTO? IMMediate Chapter Multimeter Command Reference Appendix a Appendix B Contents HEWLETT-PACKARD Warranty Statement Documentation History Manufacturer’s Name July 31 Jim White, QA Manager Business Reply Mail Page Using This Chapter HP E1312A and HP E1412A Multimeter Module Setup Setting the Module Address Switch Interrupt Priority Setting the Line Frequency ReferenceChecking the Line Frequency Reference Page Multimeter Functional Connections Switch Module Analog Bus Connections Voltage Measurement Connections Wire Ohms Measurement Connections Initial Operation HP E1312A and HP E1412A Multimeter Module Setup Chapter Function Prototype HP E1312A and HP E1412A Multimeter Module Setup Chapter Measurement Tutorial Thermal EMF ErrorsDC Voltage Measurements Thermoelectric Voltages Loading Errors dc volts Leakage Current Errors Common Mode Rejection CMR Rejecting Power Line Noise Voltages Noise Caused by Ground Loops Noise Caused by Magnetic Loops Resistance Measurements Wire Ohms Measurements Set to 2-wire ohms function Errors in High Resistance Measurements Power Dissipation EffectsMaking High-Speed DC and Resistance Measurements True RMS AC Measurements DC Current Measurement Errors Common Crest Factors Example Crest Factor Errors non-sinusoidal inputs Temperature Coefficient Errors Loading Errors ac voltsAC Measurements Below Full Scale Function and Range Change Internal Offset Correction Voltage Measured = Vin2+ Noise2 Low-Level Measurement Errors Frequency and Period Measurement Errors AC Current Measurement ErrorsMaking High-Speed AC Voltage or Current Measurements AC Signal Filter DC Input Resistance Measurement Configuration Number of Power Line Cycles Nplc Resolution Chapter HP E1312A/E1412A Multimeter Application Information SENSeZEROAUTO Offonceon Null Relative Function Math Operations CALCulate Subsystem CONFfunction DB Measurements Storing the dB Reference Value DBm MeasurementsStoring the dBm Reference Resistance Value HP E1312A/E1412A Multimeter Application Information Chapter Triggering the Multimeter TRIGgerSOURce EXTernal Checking the Trigger Source Wait-for-Trigger State Bus Triggering Example Setting the Trigger Count Checking the Trigger Count Inserting a Trigger DelayExample Inserting a Trigger Delay Default Trigger Delays Example Setting the Sample Count Querying Delay Time Sample CountChecking the Sample Count HP VTL Software Visa HP E1312A and HP E1412A Multimeter Application Examples Making Multimeter Measurements MEASure Command MEASURE2 Source Code File MEASURE1 Source Code File Init MEASURE3 Source Code File MEASURE4 Source Code File HP E1412A Multimeter and Switch Module Synchronization Synchronizing Multimeter With a Switch Module See -5 for the HP E1312A/E1412A Multimeter status system Now set up the switch module Set up the MultimeterCheck the multimeter for system errors Retrieve the readings from the multimeter Multimeter Status System Examples RST CLS *ESE Init OPC Synchopc Source Code File RST Init FETC? Synchmav Source Code File Limittst Source Code File End Loop Check the multimeter for system errorsLoop Programming Example Device ConfigurationPage HP E1312A/E1412A Multimeter Application Information Chapter Common Command Format Command TypesCommand Format Abbreviated Commands Implied Commands CommandSeparator Parameters Linking Commands PLC Multimeter Range and Resolution Tables AC Voltage Range versus Resolution Scpi Command ReferenceAC Current Range versus Resolution ABORt Related Commands INITiate, TRIGgerAborting a Measurement Subsystem Syntax CALCulateValid Math/Measurement Function Combinations AVERageCOUNt? AVERageAVERage?AVERageMAXimum? AVERageMINimum? DBREFerence? DBREFerenceDBMREFerence DBMREFerence? FUNCtion? FUNCtionParameter Summary Example Example Query the Calculate Math Function LIMitLOWer? LIMitLOWerLIMitUPPer LIMitUPPer? NULLOFFSet? NULLOFFSetSTATe STATe? COUNt? CALibrationLFRequency Comments LFRequency? Example Query the Line Frequency SettingSECureCODE Example Enter a New Calibration Security Code SECureSTATe? SECureSTATeSTRing Example Set the Calibration State to Unsecured VALue STRing?VALue? Example Query the Calibration Message Zeroauto CAL? CALibration? Command Setting CONFigure Function Range Resolution Default Settings for CONFigure Command by Function Example Making AC Current Measurements CURRentAC Example Making DC Current Measurements CURRentDC ResolutionMINMAXDEF selects the frequency function FRESistance Example Making 4-Wire Ohms Measurements PERiod Example Making 2-Wire Ohms Measurements Resolution Minmaxdef Example Making AC Voltage Measurements VOLTageAC Example Making DC Voltage Measurements VOLTageDC Sense HI and LO input VOLTageDCRATio String Returned CONFigure? POINts? Data Example Transferring Stored Readings to Output Buffer FETCh? IMMediate INITiateExample Placing Multimeter in Wait-For-Trigger State INPut Example Query the Input Impedance ModeIMPedanceAUTO IMPedanceAUTO? MEASure MEASCURRAC? 1,MAX CURRentAC? MEASCURRDC? .1,MAX CURRentDC? FREQuency? MEASFRES? 1500,MAX FRESistance? PERiod? RESistance? VOLTageAC? VOLTageDC? Example Making DC Voltage Ratio Measurements VOLTageDCRATio? TTLTrgSTATe OUTPutRST Condition OUTPTTLTn OFF Example Route Voltmeter Complete to Trigger Line TTLTrgSTATe?Example Query Voltmeter Complete Destination Example Transfer Readings Directly to Output Buffer READ? COUNt SAMPleRST Condition Sampcoun Example Set the Sample Count SAMPCOUN? Example Query the Sample Count SENSe Zero Auto Offonceon AUTO? Function Example Query the Measurement Function CURRentACRANGe? CURRentACRANGeExample Query the AC Current Measurement Range Example Query the AC Current Autorange Mode Example Disable AC Current AutorangingCURRentACRANGeAUTO CURRentACRANGeAUTO? CURRentACRESolution? CURRentACRESolution CURRentDCAPERture? CURRentDCAPERtureExample Set an Aperture Time of 16.7ms Example Query the Aperture Time CURRentDCNPLC? CURRentDCNPLCExample Query the DC Current Integration Time CURRentDCRANGe? CURRentDCRANGeExample Set the DC Current Range to 3A Example Query the DC Current Measurement Range Example Query the DC Current Autorange Mode Example Disable DC Current AutorangingCURRentDCRANGeAUTO CURRentDCRANGeAUTO? CURRentDCRESolution? CURRentDCRESolution DETectorBANDwidth FREQuencyAPERture DETectorBANDwidth?FREQuencyAPERture? Example Query the Detector Bandwidth FREQuencyVOLTageRANGe? FREQuencyVOLTageRANGeExample Set the Voltage Range for Frequency Measurements to Example Query the Measurement Range Example Query the Autorange Mode Example Disable AutorangingFREQuencyVOLTageRANGeAUTO FREQuencyVOLTageRANGeAUTO? FRESistanceAPERture? FRESistanceAPERture FRESistanceNPLC? FRESistanceNPLCExample Query the Integration Time FRESistanceRANGe? FRESistanceRANGe FRESistanceRANGeAUTO? FRESistanceRANGeAUTO FRESistanceRESolution? FRESistanceRESolutionExample Query the Resolution RST Condition Fresres 1mΩ 1E-03 PERiodAPERture? PERiodAPERtureRST Condition 0.1 100ms Example Set the Aperture Time PERiodVOLTageRANGe? PERiodVOLTageRANGeExample Set the Voltage Range for Period Measurements to Example Query the Period Voltage Range PERiodVOLTageRANGeAUTO? PERiodVOLTageRANGeAUTO RESistanceAPERture? RESistanceAPERture RESistanceNPLC? RESistanceNPLC RESistanceRANGe? RESistanceRANGeRST Condition Resrang 1kΩ Example Change the Range RESistanceRANGeAUTO? RESistanceRANGeAUTO RESistanceRESolution? RESistanceRESolutionExample Change the Resolution VOLTageACRANGe? VOLTageACRANGe VOLTageACRANGeAUTO Example Disable AC Voltage AutorangingVOLTageACRANGeAUTO? VOLTageACRESolution? VOLTageACRESolutionRST Condition 1E-04 Example Change the Resolution VOLTageDCAPERture? VOLTageDCAPERture VOLTageDCNPLC? VOLTageDCNPLC VOLTageDCRANGe? VOLTageDCRANGe VOLTageDCRANGeAUTO? VOLTageDCRANGeAUTO VOLTageDCRESolution? VOLTageDCRESolution Example Query the Autozero Mode Example Disable Autozero QUEStionableENABle PRESetSTATus QUEStionableCONDition? QUEStionableEVENt? QUEStionableENABle? Example Reading the Error Queue ERRor?SYSTem VERSion? RST Condition Trigcoun Example Set the Trigger Count TRIGger Example Set the Trigger Delay DELayExample Query the Trigger Count DELayAUTO DELay?Example Query the Trigger Delay Example Disable Automatic Trigger Delay Example Query the Trigger Delay Mode DELayAUTO? SOURce Related Commands INITiate, READ?, MEAS?Example Set the Sample Source Example Query the Trigger Source SOURce? Category Command Title Description Ieee 488.2 Common Command Quick Reference ESE and *ESE? Example Enable All Error Events ESR? RST does not affect SRE and *SRE? STB? HP E1412A C-size 6½-Digit Multimeters Scpi Command Quick Reference Data 67sMINMAX Zeroauto Offonceon DC Characteristics HP E1312A and HP E1412A Multimeter Specifications 60 Hz 50 Hz Measuring Characteristics Operating Characteristics True RMS AC AC Characteristics True RMS AC Voltage System Speeds 10 Accuracy Specifications ±% of reading 1 Frequency and Period Characteristics Configuration Rates 14/sec Autorange Time General Specifications Understanding the % of reading Error To Calculate Total Measurement Error Total Measurement Error Number of Digits and Overrange Interpreting Multimeter Specifications Accuracy DC Voltage, DC Current, and Resistance Measurements Configuring for High Accuracy Measurements Execution Errors 113Undefined header 112Program mnemonic too long121Invalid character in number 123Numeric overflow To -178Expression errors To -168Block data errors221Settings conflict 211Trigger ignored 330Self-test failed 350Too many errors440Query Unterminated after indefinite response Cannot use overload as math reference Cannot achieve requested resolution Cal signal frequency out of range Cal signal measurement out of rangeCal secured Invalid secure code No cal for this function or range HP E1312A and HP E1412A Multimeter Error Messages Appendix B Measurement Speed and Accuracy Trade-offs Measurement Speed and Accuracy Trade-offs Appendix C HP E1312A/E1412 Special Function General Guidelines for Increasing Measurement Speed Minimize Number Command Response SessionsAvoid Function Changes Avoid Aperture Changes Decrease Aperture Time or NPLCs Set Autozero to Once or OFF Turn Autorange INITFETCH? Setting the Resolution Index 197 Index 124 Index Index Error, 180 See online help Cycles, 27, 38, 123, 132, 140 Errors 130 Setting resolution, 15, 38 160 Index