HP WaterSkis E1312A, WaterSkis E1412A 29

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

Contents

HP E1312A/E1412A User’s Manual and SCPI Programming Guide Edition HP E1312A and HP E1412A Multimeter Module Setup General Information Checking the Line Frequency Reference Page Multimeter Command Reference (continued) :AVERage:AVERage :AVERage:COUNt :AVERage:MAXimum :AVERage:MINimum [:IMMediate] :IMPedance:AUTO :IMPedance:AUTO :CURRent:AC :CURRent[:DC] Multimeter Command Reference (continued) [SENSe:] (continued) FREQuency:VOLTage:RANGe:AUTO FREQuency:VOLTage:RANGe:AUTO PERiod:VOLTage:RANGe:AUTO VOLTage[:DC]:RESolution ZERO:AUTO ZERO:AUTO :PRESet :QUEStionable:CONDition Appendix B Appendix C Page Certification HEWLETT-PACKARDWARRANTY STATEMENT U.S. Government Restricted Rights Documentation History Trademarks Safety Symbols WARNINGS HP E1312A Declaration of Conformity according to ISO/IEC Guide 22 and EN Manufacturer’s Name: Manufacturer’s Address: Product Name: HP E1412A Declaration of Conformity July 31 Reader Comment Sheet In appreciation of your time, we will enter you in a quarterly drawing for a Hewlett-Packard BUSINESS REPLY MAIL HEWLETT-PACKARDCOMPANY Measurement Systems Division Learning Products Department P.O. Box Page HP E1312A and HP E1412A Multimeter Module Setup Note +50 +60 Page Multimeter Functional Connections Page Page Programming the Multimeter Page Page HP E1312A/E1412A Multimeter Application Information Page Page Page Page The following program shows SCPI examples used to store a NULL value 30 HP E1312A/E1412A Multimeter Application Information Page sinewave inputs only Common Crest Factors Example For low frequencies where (f × Rs) ≤ 15(106)Ω ∙ Hz: : 15(10 Hz: -100 × Rs Error (%) = R----s---+-----1M--------Ω Voltage Measured = Vin2+ Noise2 fast filter seconds, and is useful for frequencies above 200Hz. The medium filter slow filter DC Blocking Circuitry function This applies to all measurement functions Table 2-6.Resolution of Power Line Cycles DC voltage ratio measurements use both the •Set the resolution using the following commands: 38 HP E1312A/E1412A Multimeter Application Information Integration time applies to dc voltage, dc current, resistance and Except for NPLCs are not applicable to the •Set integration time using the following commands: s are not applicable for the zero reading When autozero is disabled Use the following command to disable autozero or select the ONCE [SENSe:]ZERO:AUTO OFF|ONCE|ON 1.Select the desired math function: 2.Enable the selected math function by turning the calculate state on: Result = reading - null value •Does not apply to the DC-to-DCRatio measurements The null value is adjustable and you can set it to any value between 0 and Two Ways to Store the NULL Offset Value Storing the dB Reference Value Storing the dBm Reference Resistance Value •Applies to all measurement functions •You can set the upper and lower limits to any value between 0 and Use the following commands to activate the The 44 HP E1312A/E1412A Multimeter Application Information Page source through HP E1300/E1301A B-SizeMainframes) For example, the following program statement selects the external trigger BNC connector as the trigger source Checking the Trigger Source The Wait-for-TriggerState The multimeter is triggered from the VXIbus. This mode is selected with the command You can also trigger the multimeter from the Substituting MIN for the number parameter sets the trigger count to Example: Setting the Trigger Count Example: Inserting a Trigger Delay command returns one of the following numbers to the output buffer: The present trigger count (1 through 50,000) if neither •The minimum trigger count available (1) if MIN is specified NOTE: Example: Setting the Sample Count The present trigger delay (1 •The minimum trigger delay available (1μs) if MIN is specified •The maximum trigger delay available (3600 seconds) if MAX is specified 10 readings are taken, the multimeter returns to the idle state plug&play C Programs Project Type: QuickWin application (.EXE) Project Files: Hardware Used MEASure Command 1.Use the MEASure command to make a single measurement 2.Make several externally triggered measurements 3.Maximize measurement speed on multiple measurements Measurement Format •Readings sent to the output buffer can consist of two different lengths (bytes or characters) in Real ASCII format: Each measurement is terminated with a Line Feed by commas and EOI is sent only with the last byte. For example: Trigger source •The sample count (SAMP:COUN) is set for 10 samples per trigger 30 measurements; 10 samples for each of three triggers MEASURE3 Source Code File The autozero function is disabled to speed up the measurement process. See the MEASURE4 Source Code File Maximizing Accuracy (most accurate resolution, longer integration time) •The sample count (SAMP:COUN) is set for 10 samples per external trigger This example uses the 56 HP E1312A/E1412A Multimeter Application Information Page Page HP E1412A SCAN Source Code File SCPI command sequences for the program are as follows **** Set up the Multimeter **** Now set up the switch module Retrieve the readings from the multimeter Page SYNCHOPC Source Code File Loop SPOLL - read the multimeter’s status byte until bit 5 (ESB) goes high. End Loop SYNCHMAV Source Code File NOTE: If 62 HP E1312A/E1412A Multimeter Application Information LIMITTST Source Code File Enter response into the computer Wait 1 second End Loop Device Configuration Visual Engineering Environment HP VEE Select I/O Program Description Strip Chart Object In parallel with the object is a object that displays the readings of the eight channels. The HP VEE Visual Engineering Environment HP VEE The Most Productive Language for Test and Measurement HP VEE Visual Engineering Environment Technical Data Multimeter Command Reference Command A colon (:) always separates one command from the next lower level command as Separator shown below: Abbreviated Commands Parameters Parameter Types Optional Parameters Table 3-1.DC Voltage Resolution versus Integration Time or Aperture Time Table 3-2.DC Current Resolution versus Integration Time or Aperture Time Table 3-4.AC Voltage: Range versus Resolution Table 3-5.AC Current: Range versus Resolution command subsystem removes the multimeter from the wait-for-trigger state and places it in the idle state is only effective when the trigger source is Subsystem Syntax Valid Math/Measurement Function Combinations CALCulate:AVERage:AVERage reads the average of all readings taken since was enabled commands). The average value is cleared when CALCulate:AVERage:COUNt stores a relative value in the dB Relative Register You can set the relative value to any number between 200dBm (the values). The dB reference is stored in volatile memory Example Set the DB Reference Value Parameter Summary selects the math function to be used. One function is enabled at a time with the default. The selected function MUST be enabled with Example Set the Lower Limit queries the lower limit Example Query the Lower Limit Set for the LIMit Math Operation Example Set the Upper Limit queries the upper limit stores a null value in the multimeter’s Null Register You can set the null value to any number between 0 and 120% of the highest range, for the present function –120% of the highest range The wrong line frequency setting will cause reading errors to occur :STRing <quoted string cal_value Example Query the Number of Occurrences of Point Calibrations Comments • Example Query the Line Frequency Setting new code Example Enter a New Calibration Security Code code command. The state is stored in <code •*RST does not change the state Example Set the Calibration State to Unsecured Example Enter Calibration Information to Record the Next Calibration Date CALibration:STRing Example Query the Calibration Message CALibration:VALue cal_value mode Example Calibrate the Active Function and Range Using the CAL:VALue does not esolution The CONFigure command RANGe and RESolution parameters are optional. You RESolution Default Settings for CONFigure Command by Function CONFigure:CURRent:AC [<range>|MIN|MAX|DEF|AUTO resolution <range <resolution resolution| CONFigure:CURRent[:DC] [<range>|MIN|MAX|DEF|AUTO >|MIN|MAX|DEF]] resolution | For range: MIN = 10 mA; MAX = 3A e.g Page CONFigure:FRESistance [<range>|MIN|MAX|DEF|AUTO For range: MIN = 100 Ω; MAX =100MΩ To specify a resolution while autoranging, you must specify the parameter; Page CONFigure:RESistance [<range>|MIN|MAX|DEF|AUTO resolution |MIN|MAX|DEF For range: MIN = 100Ω; MAX =100MΩ •To specify a MIN or MAX resolution while autoranging, you must specify for range; CONFigure:VOLTage:AC [<range>|MIN|MAX|DEF|AUTO •The MIN and MAX parameters select the minimum or maximum values for range: For range: MIN = 0.1V; MAX Example Making AC Voltage Measurements CONFigure[:VOLTage[:DC]] [<range>|MIN|MAX|DEF|AUTO For range: MIN = 100mV; MAX Example Making DC Voltage Measurements 94 Multimeter Command Reference dc signal voltage Hi and LO input Sense HI and LO input It returns a quoted string to the output buffer in the following format: “<function> <parameter>,<parameter>” If you specify •Related Commands: CONFigure, MEASure Example Querying the Multimeter Configuration Page The FETCh? command retrieves measurements stored in the module’s internal This command is most commonly used with CONFigure without error • The Multimeter’s internal memory stores 512 readings maximum Example Transferring Stored Readings to Output Buffer This command is most commonly used with CONFigure. See the section titled subsystem to control the behavior of the trigger system •To transfer readings from memory to the output buffer, use the FETCh? command •*RST Condition: *RST places the multimeter in the idle state Example Placing Multimeter in Wait-For-TriggerState Conditions: Example Query the Input Impedance Mode Page Page Page Page Page Page Page Page Page Example Making DC Voltage Ratio Measurements complete signal to the VXIbus TTL trigger lines voltmeter complete The multimeter generates the The VXIbus trigger lines are More than one TTL output trigger line can be enabled at one time Example Route Voltmeter Complete to Trigger Line voltmeter complete Example Query Voltmeter Complete Destination The READ? command is most commonly used with CONFigure to: Place the multimeter in the Comments Each reading sent to the output buffer is terminated with a Line Feed Example Transfer Readings Directly to Output Buffer number •*RST Condition: SAMP:COUN Example Set the Sample Count Example Query the Sample Count --Function, Range and Resolution --Aperture Time and Number of Power Line Cycles --Bandwidth --Autozero 116 Multimeter Command Reference Page function Change Measurement Function Example Query the Measurement Function Example Query the AC Current Measurement Range enables or disables the autorange function for AC current measurements When autoranging is If you explicitly select a range using Example Disable AC Current Autoranging selects the resolution for AC current measurements. See Table 3-5on page resolution|MIN|MAX •Specify resolution in the same units as the measurement function •If autoranging is required, set the resolution using the MIN or MAX parameter 1.66667 seconds (60Hz) or 2 seconds (50Hz) seconds (60Hz) or (50Hz) Example Set an Aperture Time of 16.7ms returns one of the following numbers to the output buffer •The CURR:DC:NPLC command overrides the results of previously executed •*RST Condition: 10 PLC 10 PLC Example Set the DC Current Integration Time in PLCs •The present integration time in PLCs if MINimum or MAXimum is not specified •You must select a range using CURRent:DC:RANGe before specifying resolution Example Set the DC Current Range to 3A The minimum current range available (10mA) if MIN is specified Example Query the DC Current Measurement Range function for DC current measurements Example Disable DC Current Autoranging Example Query the DC Current Autorange Mode selects the resolution for DC current measurements Changing the resolution also changes the The present current resolution selected if •The minimum current resolution available (1μA) if MIN is specified •The maximum current resolution available (100μA) if MAX is specified Condition Example Set the ac Signal Filter for Fast Measurements From 200Hz to 300kHz Example Query the Detector Bandwidth <time •MIN = 0.01, MAX •*RST Condition: 0.1 seconds 0.1 seconds selects the voltage range for the signal level of frequency measurements •The FREQ:VOLT:RANG command overrides the range setting from a previous y command Example Set the Voltage Range for Frequency Measurements to enables or disables the autorange function for the signal level of frequency measurements Example Disable Autoranging returns a number to show whether the autorange mode is enabled or disabled: “ . The number is sent to the output buffer Comments • MIN sets the aperture time to 0.333ms. MAX sets the aperture time to The minimum aperture time available (.333ms) if MIN is specified The maximum aperture time available (1.67s @ 60Hz; 2s @ 50Hz) if [SENSe:]FRESistance:NPLCycles •The FRES:NPLC command overrides the results of previously executed commands (the last command executed has priority) Example Set the Integration Time in PLCs [SENSe:]FRESistance:NPLC? [MIN|MAX] •You must select a range using FRESistance:RANGe before specifying resolution •*RST Condition: FRES:RANG 1kΩ (1E+03) (1E+03) Example Set Four-WireResistance Range to 10MΩ •The present resistance range selected if MIN or MAX is not specified function for 4-wireresistance measurements Example Put 4-wireResistance Measurements in the Autorange Mode selects the resolution for 4-wire resistance measurements •*RST Condition: FRES:RES 1mΩ (1E-03) (1E-03) time 1 second •*RST Condition: 0.1 (100ms) 0.1 (100ms) Example Set the Aperture Time [SENSe:]PERiod:VOLTage:RANGe <range> selects the voltage range for the signal level of period measurements Example Set the Voltage Range for Period Measurements to 0.1, 1, 10, 100 or 300 corresponding to the range set MIN returns Page •The RES:APER command overrides the results of previously executed [SENSe:]RESistance:NPLCycles •The RES:NPLC command overrides the results of a previously executed command (the last command executed has priority) [SENSe:]RESistance:NPLC? [MIN|MAX] The minimum integration time available (0.02) if MIN is specified •*RST Condition: RES:RANG 1kΩ Example Change the Range •The present resistance range selected if MIN or MAX is not specified. Only the function for resistance measurements •*RST Condition: Based on the *RST values for the RESistance:NPLC command Example Change the Resolution •You must select a range using VOLTage:AC:RANGe before specifying resolution •Specifying a fixed range disables the autorange mode setting The minimum voltage range available with the The maximum voltage range available with the [SENSe:]VOLTage:AC:RANGe:AUTO <mode> enables or disables the autorange function for AC voltage measurements In order to specify an aperture time of s, you must select a fixed range (e.g Example Disable AC Voltage Autoranging selects the resolution for AC voltage measurements. See Table on page to avoid a settings conflict error when specifying resolution •The VOLT:AC:RES command overrides the resolution setting from a previous *RST Condition: 1E-04 The maximum aperture time available (1.67s @ 60Hz; 2 s @ 50Hz) if Page •You must select a range using VOLTage:DC:RANGe before specifying resolution •Specifying a fixed range disables the autorange mode by setting [SENSe:]VOLTage[:DC]:RANGe:AUTO <mode> enables or disables the autorange function for DC voltage measurements [SENSe:]VOLTage[:DC]:RANGe:AUTO 150 Multimeter Command Reference selects the resolution for DC voltage measurements •The VOLT:DC:RES command overrides the resolution setting from a previous •*RST Condition: Based on the *RST values for the VOLTage:NPLC command •*RST Condition: ZERO:AUTO ON (enables autozero mode) Example Disable Autozero •“ 0” ( OFF or ONCE) if autozero is disabled or set for one time •“ 1” ON if autozero is enabled Example Query the Autozero Mode The STATus subsystem reports the bit values of the Questionable Data/Signal Event Register and to read the summary bits from the Status Byte Register event register and an enable register. The commands in the STATus:QUEStionable subsystem control and monitor these registers The STATus system contains seven registers, four of which are under IEEE Page The SYSTem command subsystem returns error numbers and their associated instrument complies One error is removed from the error queue each time the When the error queue is empty, subsequent Example Reading the Error Queue •*RST Condition: TRIG:COUN Example Set the Trigger Count Example Query the Trigger Count seconds NOTE: This delay also occurs between each sample when Example Set the Trigger Delay Example Query the Trigger Delay Example Disable Automatic Trigger Delay TRIGger:DELay:AUTO Example Query the Trigger Delay Mode Disable automatic trigger delay TRIG:DEL:AUTO source •Related Commands: INITiate, READ?, MEAS Example Set the Sample Source Example Query the Trigger Source unmask 162 Multimeter Command Reference Executable when Initiated: Yes Coupled Command: No Related Commands: STATus:PRESet *RST Condition: none Comments • Executable when Initiated: Yes Power-OnCondition: register is cleared Related Commands: *OPC?, *WAI Related Commands: *OPC, *WAI *RST does not affect: •Power-OnCondition: no bits are enabled Example Enable Service Request on Message Available Bit Related Commands: *SRE Comments • Executable when Initiated: No •*RST Condition: none The following tables summarize SCPI commands for the HP E1312A B-sizeand HP E1412A C-size 6½-DigitMultimeters Description 168 Multimeter Command Reference Page 170 Multimeter Command Reference HP E1312A and HP E1412A Multimeter Specifications Accuracy Specifications ± (% of reading + % of range) [1] Appendix A HP E1312A and HP E1412A Multimeter Specifications Measuring Characteristics DC Voltage Resistance DC Current DC:DC Ratio Operating Characteristics [8] System Speeds [10] Additional Error with Autozero OFF Settling Considerations Measurement Considerations [1] 174 HP E1312A and HP E1412A Multimeter Specifications Measurement Noise Rejection [7] True RMS AC Voltage True RMS AC Current Operating Characteristics System Speeds [10], [11] [10], [11] Function or Range Change: 5/sec Accuracy Specifications ±(% of reading) [1] [4] Additional Low-FrequencyErrors (% of reading) [4] Integration Time (number PLCs) Frequency 100 & Operating Characteristics [5] System Speeds [5] Page Understanding the “% of reading” Error Understanding the “% of range” Error Total Measurement Error Total Measurement Error Number of Digits and Overrange Sensitivity Resolution Accuracy Transfer Accuracy 24-HourAccuracy 90-Dayand 1-YearAccuracy Temperature Coefficients DC Voltage, DC Current, and Resistance Measurements: AC Voltage and AC Current Measurements: Frequency and Period Measurements: HP E1312A and HP E1412A Multimeter Error Messages -112 Program mnemonic too long string contains more than the maximum 12 characters allowed in the -113 Undefined header -121 Invalid character in number -123 Numeric overflow -160to -168 Block data errors The multimeter does not accept block data -170to -178 Expression errors The multimeter does not accept mathematical expressions -211 Trigger ignored -330 Self-testfailed -350 Too many errors Query -440 Query UNTERMINATED after indefinite response 501Isolator UART framing error 532Cannot achieve requested resolution 540Cannot use overload as math reference HP E1312A and HP E1412A Service Manual 602RAM read/write failed 603A/D sync stuck 621AC rms full scale failed 622Frequency counter failed 623Cannot calibrate precharge 625I/O processor does not respond 626I/O processor failed self-test 709No cal for this function or range 710Full scale correction out of range 720Cal DCV offset out of range 721Cal DCI offset out of range 722Cal RES offset out of range Page Measurement Speed and Accuracy Trade-offs Special Commands and Their Equivalent [SENSe:] Command 194 Measurement Speed and Accuracy Trade-offs Page Page Page Setting the Resolution INIT;:FETCH The aperture time or NPLC is set as a result of specifying the resolution > parameter in the Numerics range, 87, 119– 120 range/resolution, 87, 102 resolution A(continued) C(continued) autozero Current (continued) Current ac (continued) range/resolution, resolution, 121 specifications, 174– specifications autozero, 83, 152, 197 math function F(continued) NPLC, 123, 132, 140 querying, 122– 123, 131– 132, 136, 139– 140, 147– setting, 122– 123, 131– 132, 136, 139– 140, 147– configuration (continued) dBm, 43, 75 dc current error, 180– See P(continued) Power Line cycles, 27, 38, 123, 132, 140 cycles noise, rejecting voltages R(continued) errors S(continued) 4-wireohms, 90, 105, 133– 134 ac current, 87 delays, 49– 50, 157– 159 upper/lower limits, 44 T(continued) dc, 25– 28 offset