Resistance Measurements | HP WaterSkis E1412A, WaterSkis E1312A

Resistance Measurements

4-Wire Ohms Measurements

The HP E1312A and HP E1412A offer two methods for measuring resistance: 2-wire and 4-wire ohms. For both methods, the test current flows from the input HI terminal and then through the resistor being measured. For 2-wire ohms, the voltage drop across the resistor being measured is sensed internal to the multimeter. Therefore, input cable resistance is also measured. For 4-wire ohms, separate “sense” connections are required. Since no current flows in the HI-LO “Sense” terminal cables, the resistances in these cables do not give a measurement error.

The errors discussed previously for dc voltage measurements also apply to resistance measurements. Additional error sources unique to resistance measurements are discussed in the following sections.

The 4-wire ohms method provides the most accurate way to measure small resistances. Errors due to test cable resistances and contact resistances are reduced using this method. Four-wire ohms is often used in automated test applications where long cable lengths, numerous connections, or switches exist between the multimeter and the device-under-test. The recommended connections for 4-wire ohms measurements are shown below.

Chapter 2

HP E1312A/E1412A Multimeter Application Information 29

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HP WaterSkis E1412A, WaterSkis E1312A manual Resistance Measurements, Wire Ohms Measurements

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 Checking the Line Frequency Reference Setting the Line Frequency ReferenceInterrupt Priority 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 DC Voltage Measurements Thermal EMF ErrorsMeasurement Tutorial 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 Making High-Speed DC and Resistance Measurements Power Dissipation EffectsErrors in High 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 Making High-Speed AC Voltage or Current Measurements AC Current Measurement ErrorsFrequency and Period Measurement Errors 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 dBm Reference Resistance Value DBm MeasurementsStoring the dB Reference Value HP E1312A/E1412A Multimeter Application Information Chapter Triggering the Multimeter TRIGgerSOURce EXTernal Checking the Trigger Source Wait-for-Trigger State Bus Triggering Example Inserting a Trigger Delay Checking the Trigger Count Inserting a Trigger DelayExample Setting the Trigger Count Default Trigger Delays Checking the Sample Count Querying Delay Time Sample CountExample Setting 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 Loop End Loop Check the multimeter for system errorsLimittst Source Code File Programming Example Device ConfigurationPage HP E1312A/E1412A Multimeter Application Information Chapter Command Format Command TypesCommon Command Format Separator CommandAbbreviated Commands Implied Commands Parameters Linking Commands PLC Multimeter Range and Resolution Tables AC Current Range versus Resolution Scpi Command ReferenceAC Voltage Range versus Resolution Aborting a Measurement Related Commands INITiate, TRIGgerABORt Valid Math/Measurement Function Combinations CALCulateSubsystem Syntax 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? Example Placing Multimeter in Wait-For-Trigger State INITiateIMMediate 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? RST Condition OUTPTTLTn OFF OUTPutTTLTrgSTATe Example Query Voltmeter Complete Destination TTLTrgSTATe?Example Route Voltmeter Complete to Trigger Line Example Transfer Readings Directly to Output Buffer READ? RST Condition Sampcoun Example Set the Sample Count SAMPleCOUNt SAMPCOUN? Example Query the Sample Count SENSe Zero Auto Offonceon AUTO? Function Example Query the Measurement Function Example Query the AC Current Measurement Range CURRentACRANGeCURRentACRANGe? 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 Example Query the DC Current Integration Time CURRentDCNPLCCURRentDCNPLC? 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 Example Query the Integration Time FRESistanceNPLCFRESistanceNPLC? FRESistanceRANGe? FRESistanceRANGe FRESistanceRANGeAUTO? FRESistanceRANGeAUTO FRESistanceRESolution? FRESistanceRESolutionExample Query the Resolution RST Condition Fresres 1mΩ 1E-03 RST Condition 0.1 100ms Example Set the Aperture Time PERiodAPERturePERiodAPERture? PERiodVOLTageRANGe? PERiodVOLTageRANGeExample Set the Voltage Range for Period Measurements to Example Query the Period Voltage Range PERiodVOLTageRANGeAUTO? PERiodVOLTageRANGeAUTO RESistanceAPERture? RESistanceAPERture RESistanceNPLC? RESistanceNPLC RST Condition Resrang 1kΩ Example Change the Range RESistanceRANGeRESistanceRANGe? RESistanceRANGeAUTO? RESistanceRANGeAUTO Example Change the Resolution RESistanceRESolutionRESistanceRESolution? VOLTageACRANGe? VOLTageACRANGe VOLTageACRANGeAUTO? Example Disable AC Voltage AutorangingVOLTageACRANGeAUTO RST Condition 1E-04 Example Change the Resolution VOLTageACRESolutionVOLTageACRESolution? 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 Query the Trigger Count DELayExample Set the Trigger Delay DELayAUTO DELay?Example Query the Trigger Delay Example Disable Automatic Trigger Delay Example Query the Trigger Delay Mode DELayAUTO? Example Set the Sample Source Related Commands INITiate, READ?, MEAS?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 440Query Unterminated after indefinite response 350Too many errors330Self-test failed 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 Avoid Function Changes Avoid Aperture Changes Minimize Number Command Response SessionsGeneral Guidelines for Increasing Measurement Speed 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