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HP 3478A Digital Multimeter

1. r Si Se NOTE From any trigger mode readings may also be initiated by the HP IB GET command External trigger is disabled by the T1 T3 T4 or T5 command 31 VOLTAGE MEASUREMENTS Measuring Voltages Whether you use your 3478A on the bench or as part of a sophisticated test system probably most of your measurements will be voltage measurements If you have special requirements in taking voltage measurements be sure to read the sections on Optimizing Reading Rates Display Autozero and Triggering modes A complete Table of Specifications is given in Chapter 4 of this manual DC Voltage Measurements v DC voltages measured on the 3478A are both simple and straightforward Press the DC Voltage key and either select the appropriate range or allow the multimeter to autorange Read the display directly no multiplying the reading by the range etc for the measured voltage Up to 1 microvolt of noise may be seen on the 30 millivolt range DESIGNED FOR LA Command SYSTEMS F1 Selects the DC Volts mode also H1 AC Voltage Measurements Like DC voltage measurements AC measurements are very straightforward Press the AC Voltage key and appropriate range key s The display is read directly for the measured voltage The 3478A uses a True RMS to DC converter for AC voltage and current measurements Unlike multimeters that use an average detector the True RMS converter allows accurate measurement of voltage
2. Before running the program make cer tain that the 34784 is the only instru ment on the Bus Remove the test EROR PNE DUE ERES an leads and external trigger and VM NEVE GUGTRE Tate METAM complete cables Follow the instruc Geet e a Po ao tions given on the CRT FROM THE 3478A 34789A VERIFICATION PROGRAM TEST PROGRESS IS SHOWN ON THE DISPLAY ERRORS ARE NOTED ON THE PRINTER PRESS ECONT3 KEY Response Press the CONT key TO BEGIN WHAT IS ADDRESS OF THE 3478A Response f the address of the FACTORY AODRESE 7 23 gt 3478A is 723 then just PRESS CEND LINE3 KEY press the END LINE key If the address is different enter the new address 3 digits and press END LINE 71 SELF TEST SELF TEST PASSES Response Press the 3478A SRQ TESTING FRONT PANEL SRa key The calculator will continue to beep every 10 seconds until the key is pressed PRESS 3478A FRONT PANEL SRO KEY TESTING FOR PROGRAM CODES PASSES ILLEGAL CODE TEST Response You will be asked to watch the 3478A display WATCH 3478A DISPLAY PASSES RANGE FUNCTION as it completes the AUTOZERO TEST Be i PASSES DISPLAY TEST verification The final PASSES TRIGGER TEST hp 85 displ indi PASSES PRESET COMMANDS TEST hp Isplay indicates READINGS TEST PASSES that all tests passed XXX VERIFICATION COMPLETE END OF VERIFICATION PROGRAM What the Test Does Test 1 SELF TEST This test verifies that the 3478A r
3. OUTPUT 723 F2R 2RAZ1N4T3 Instructions are implemented as they are received over the Bus In other words the 3478A will go to the ac volts mode before it goes to the lowest range It will go to the lowest range before autorange it will autorange before turning autozero on etc The last thing it will do is trigger for the measurement A very important matter to keep in mind is to use the proper computer syntax Remember that the examples given in this chapter were written for a computer such as the hp 85F Check your computer UO manual for the correct syntax and in the examples given use that syntax Home Commands There is a series of eight preset commands conveniently provided in the 3478A which greatly ease programming These commands called HOME commands set the 3478A to predetermined states as defined in Table 3 1 In the sample pro gram given earlier we ended with a string of six commands which could actually be replaced with one HOME command H2 Table 3 1 Home Commands Command Description HO HOME Command The 34784 is placed into the DC volts function F1 autorange RA trigger hold T4 4 1 2 digit display N4 and autozero on Z1 Any result ready to be output to the bus or display is erased External trigger input is disabled This command is equal to F1TAR 2RAZ1N4 The meter will wait for a trigger command such as T3 or T5 Measure DC Volts This function is the same as the HO command except that a
4. Reading Resolution set On the 3MQ range add an additional offset of 0 001696 Range 5 Digit 55 Digit 4 Digit 3 Digit of reading On the 30MQ range add an additional offset of q _I_E E EM SEN E T 0 008396 of reading 30 Q 30 3099 Q0 10020 1mQ 10mQ 300 Q 303 099 Q 1mQ 10mQ e ur Auto Zero Off 3kQ 3 03099 kQ 10m2 100mQ X 5 30 kQ 30 3099kQ 100mQ 19 d NE digit for a stable d Dou Se GER add 300kQ 1303 099kQ 19 10 Q 100 Q counts to accuracy specification for range counts i for 3002 3 counts for 3KQ through 300K2 ranges 8 counts SMo 3 03099M9 10 Q i 100 Q 1 kQ for 3MQ range and 33 counts for 30MQ range 30MQ 30 3099MQ2 100 f 1 kQ 10 kQ Input Protection non destructive Temperature Coefficient o zi o o o Hi source to Lo source 350V peak EN E to Cal Temp 5 C Cal Temp 5 C to 55 C i 5 digit display auto zero ON Misense to Lo Sense ES BUY peak of reading number of counts C Hi or Lo to Earth Ground 5OOV peak z Measurement Accuracy l Range Temperature Coefficient of reading number of counts 302 0 003 5 Auto zero ON 4 wire ohms 3002 0 0009 5 3k 300kQ 0 0009 05 3MQ 0 0021 Op 5 Digit Mode 30MQ 0 021 05 Cal Temp 1 C Cal Temp 5 C Current Through Unknown Meme cmo MEL E NU L Range 300 3009 3k0 30k0 300k0 3M9 30MQ i i SE O Current 1mA 1mA 1mA 1004A 10 1 4 100nA 300 0 023 35 0 027 41
5. Your 3478A has the capability of measuring DC or True RMS AC Currents up to 3 amps in two ranges The current function is protected by a 3 Amp 250V fuse If the fuse opens refer to Chapter IV before replacing The illustration below shows the internal current shunt and fuse used in the 3478A The unknown current flowing through the current shunt produces a voltage which can then be measured Current inputs of greater than 1 amp may cause the current shunt to change value slightly due to self heating somewhat like a thermistor This may cause inac curacies in the measurement Sufficient time should be allowed for the circuitry to settle after the measurement is complete before other critical current measurements are made DC Current Press the DC Amps key and select the appropriate range or let the 3478A autorange When measuring currents remove all other test leads from the 3478A front panel There are two ranges available for current measurements the 300 milliamp range and the 3 amp range Up to 10 microamps of noise may be seen on the 300 milliamp range AC Current Measuring ac current is identical to dc current except that you use the AC Amps key to select the measurement function The specified range of the AC ammeter is 30 milliamps to 3 amps Lower accuracy readings down to 1 milliamp may be taken on the 300 milliamp range Up to several hundred counts of residual offset may be seen on the 5 digit display with the input ope
6. 47 Barnes industrial Road South P O Box 5007 WALLINGFORD CT 06492 Tel 203 265 7801 A CM CP E MS Florida Hewlett Packard Co PO Box 24210 2727 N W 62nd Street FORT LAUDERDALE FL 33309 Tel 305 973 2600 CM CP E MP Hewlett Packard Co 4080 Woodcock Drive 132 Brownett Building JACKSONVILLE FL 32207 Tel 904 398 0663 OMC EMS Hewlett Packard Co P O Box 13910 6177 Lake Ellenor Drive ORLANDO FL 32809 Tel 305 859 2900 A CM CP E MS Hewlett Packard Co 6425 N Pensacola Blvd Suite 4 Building 1 PENSACOLA FL 32575 Tel 904 476 8422 A CM MS Hewlett Packard Co 110 South Hoover Suite 120 Vanguard Bldg TAMPA FL 33609 Tel 813 872 0900 A CM CS E M Georgia Hewlett Packard Co P O Box 105005 2000 South Park Place ATLANTA GA 30339 Tel 404 955 1500 Telex 810 766 4890 A CM CP E MP Hewlett Packard Co Executive Park Suite 306 PO Box 816 AUGUSTA GA 30907 Tel 404 736 0592 CM MS Hewlett Packard Co PO Box 2103 1172 N Davis Drive WARNER ROBINS GA 31098 Tel 912 922 0449 CM E Hawaii Hewlett Packard Co Kawaiahao Plaza Suite 190 567 South King Street HONOLULU HI 96813 Tel 808 526 1555 A CM CS E MS Idaho Hewlett Packard Co 11311 Chinden Boulevard BOISE ID 83707 Tel 208 376 6000 CM CS M Illinois Hewlett Packard Co 211 Prospect Road BLOOMINGTON IL 61701 Tel 309 663 0383 CM CS MS Hewlett Packard Co 1100 31st Street DOWNERS GROV
7. PLC s during an A D conversion The integration time is not the same as the time for one measurement The integration time is the time period in PLC s during which the input voltage is sampled by the voltmeter At 4 1 2 digit display the time required for one integration cycle is one PLC 16 66 mS at 60Hz line fre quency 20 mS for 50Hz The 3478A determines the line frequency by the set ting of the 50 60Hz switch on the rear panel In the 3 1 2 digit mode the integra tion time is 1 PLC Normal Mode Rejection NMR is the ability of a voltmeter to accurately measure dc voltages in the presence of ac voltages at power line fre quencies The 3478A has much better NMR at 4 1 2 digit display than it does at 3 1 2 digit display 59 db vs Odb The greatest amount of NMR is available from the 5 1 2 digit mode 80 db where ten 10 readings are taken at 1 PLC integra tion time and averaged together DESIGNED FOR Commands SYSTEMS N3 Selects 3 digit display NA Selects 4 digit display N5 Selects 5 digit display DISPLAY Cont d Annunciators The 12 display annunciators located along the bottom of the display are used to indicate the state of the 3478A Table 2 3 Annunciators Annunciator Indication SRQ The SRQ annunciator indicates that the 3478A is trying to request service from the controller Refer to Chapter Ill LSTN The LSTN LISTEN annunciator turns on when the 3478A is addressed to listen via the HP IB TLK The
8. TESTING Vds EREI VERTEECATIUN TIT HEU FOR PROGRAM CODES 1440 OUTPUT Oi 7 FRRA OUTPUT DI KMB4 S VM OH IHTE D GOTO 1076 1438 ENTER ei 7 a H GOTO 1638 1468 IF agS 9998000 THEN PRINT ENABLE INTR Oa OUTPUT Di 02 ILLEGAL Co DE 34 WAIT 1898 WAIT FOR 5 Baa PRINT ZEHT ILLEGAL CODE HH O 3472A PRIWT ACCEPTED IT OH OVERLORD ERROR f PRI IFICATION HOT REDRTE FIRRBHSTI RERDIHGG TEST FA Oo b ba e 74 Dor e Dn m r OH On E H A mom RETURN m Wap i eg PN 1436 En pee eee ERN 1500 ERROR SUBROUTINE Usa 1510 STATUS D 1 A po 1528 PSSPOLL O13 1528 mc m IF EIT F 2 THEM FRIHT PRO TEST FAILED GRAM CODES PRIHT S HTHA ERROR PRI ODE TEST DIZP amp ISP MATCH Z472A DI 1546 um dcos ou use a Ed 1556 IF E 1 THEN FAINT FUNCTION EMAGLE INTE De 0 CODES F F EHHGE CODE F ET VET PE SFIUBUTOZEROS ZUGE FOR Zen TO 1 AUTOSERO isga IF E 2 THEN FFIHT DIZFLHY OR 2 8 TO 1 Ss DIGITS H H 1 E E E 1578 IF E 3 THEN PRINT DISPLAY O OW LE COMMANOS FAILURE GUTPUT a E TEES i588 IF E 4 THEN PRINT TRIGGER s EU COMMANDS Ts T 1590 IF E 5 THEN PRINT PRESET C DOE H H ISP w DISP f NERIFICATIO DIS FASSES RANGE FU DE qo HOT ICH AUTOZERA TE SCHER Ley 155 Eng H 2 T S ra Du x E a aV ix m 78 Verification Program Start Program Codes Subroutine Line 740 Set SRQ Mask For Front Panel SRO Key Line
9. eee ee 30 L Line voltage selection 64 LOCAL sa te S eO RISE 44 86 89 LOCAL LOCKOUT 44 86 90 M Manual ranging ills 22 Measurement Function keyS 4 Messages display xd 4 4 oe ip tui 13 HP B uuu ee a Au e ee E 86 89 Self test iria ee es 4 13 29 user generated o o o ooo o 15 N Normal display llle 12 O Operating characteristicS 7 Operation MNemoniC 37 Optimizing reading rateS 18 program for maximum rate 57 Output format 42 p Programming Commands 59 Programming hintS 40 54 Q Qualifier 21 Dot e doe lA de 37 INDEX Cont d Page R Range ranging eee 20 LE ert Sree E ded doe Bt 4 20 Reading t t amp soos oos e ERR ri ws 18 program for maximum rate 57 Rear panel adt cod o ee ee o 23 Switchesg olv GA RR ATA 23 68 REMOTE ce uit teet le bases eS 45 86 89 REQUIRE SERVICE SRQ 46 86 90 Repair Service 0 00000 eee eee 73 Resistance MeasurementS 25 2 WIRE EN ey E Bhan oe UE WE eS 26 AMA cc 26 extended ODMS o o ooo ooo 26 S Safety considerations 66 SENSE terminals llle 4 SERIAL POLL SPOLL 46 49 50 Shift ta At Eee i A E inda ir 4 Signal environment o ooo 18 Single trigger o o oo ooo
10. pg ED ER EB EE EC fg C8 9 E 9 7 EINEN OPERATOR S IMVAVSICTANL to service and repair 3478A DMM s Contact your local hp sales office for specific information on where to send the instrument for repair Outside of the United States repair service may be obtain ed at your local hp service center Any changes made in instruments manufactured after this print ing will be found in a Manual Changes supplement supplied with this manual Be sure to examine this supplement if one exists for this manual for any changes which apply to your instrument and record these changes in the manual j Bee EE WARNING To help minimize the possibility of electrical fire or shock hazards do not expose this instrument to rain or excess moisture IMPORTANT NOTICE Most hp service offices in the United States are NOT authorized Copyright Hewlett Packard Company 1981 P O Box 301 Loveland Colorado 80537 U S A Manual Part No 03478 90005 Printed February 1983 Microfiche Part No 03478 90055 TABLE OF CONTENTS i What is Triggering 30 Fuse Replacement 68 Trigger Indicator 30 In Case of Trouble 70 VOLTAGE MEASUREMENTS 32 Warranty Information 73 i Measuring Voltages 32 How to Obtain Repair Service 74 VOLTMETER COMPLETE 34 Serial Number 74 W
11. 0 034 41 3002 0 0045 4 0 012 5 10 0174 5 Maximum Open Circuit Voltage 3k 300kQ 0 0035 2 0 011 2 37100164 2 3MQ 0 0052 2 0 011 2 0 016 2 6 5V 30MQ 0 036 2 0 066 2 0 078 2 Maximum Reading Rates Same as dc volts except for 3MQ and 30MQ ranges For 3MQ range add 30ms for 30MQ range add 300ms per reading Qs DC CURRENT Input Characteristics Measurement Accuracy Maximum Reading i Resolution of reading number of counts Range Dd 5 Digit i EL Digit i Digit 3 Digit Auto zero ON 300mA 303 099mA HA 104A 1004A Cal Temp 5 C 3 A 3 03099 A 10A 100pA 1mA Range 90 Days 1 Year TI f Maximum Input non destructive 300mA 0 11 40 0 15 40 3A lt 1Ainput 0 14 6 0 17 6 3A from lt 250V source fuse protected 3A gt 1A input 1 0 3 i 1 0 30 81 Table 4 3 Specifications Cont d DC CURRENT Cont d Auto Zero Off 5 digit for a stable environment 1 C for 24 hrs add 110 counts to accuracy specification for 300mA range 11 counts for 3A range Temperature Coefficient O C to Cal Temp 5 C Cal Temp 5 C to 55 C 5 digit display auto zero ON 96 of reading number of counts C Range Temperature Coefficient 300mA 0 0124 5 3 A 0 012 0 5 Maximum Burden at Full Scale 1V Maximum Reading Rates Same as dc volts AC CURRENT true rms responding Input Characteristics i Maximum Reading j
12. 1 in parallel with 75pF 300KQ range 104A DC AMPS 14A resolution 300mA range to 3A full scale 3MQ range 14A Maximum Shunt Resistance 3Q 30MQ range 100 nA Maximum Burden at Full Scale 900 mV AUTOZERO What is Autozero The autozero key allows the user to selectively enable or disable the internal zero ing technique used in the 3478A Enabling autozero insures the user that any off set errors generated internal to the 3478A are continuously nulled with each reading This renders the most accuracy There are however many applications where disabling the autozero is advantageous With autozero off the internal reading rate nearly doubles This would be important in programmable applications where speed is critical Furthermore the 3478A input circuitry remains in a com pletely static state with autozero off This is useful when making measurements in extremely high impedance circuits where the internal switching transients of the 3478A may affect the reading accuracy Of course any range or function change that takes place with autozero off is automatically accompanied with an autozero update The thermal stability of the measurement environment is the most impor tant factor in deciding whether or not to turn autozero off By simply keeping the temperature of the 3478A at a fixed value you can turn autozero off without adverse effects How it Affects Measurements DC Voltage and Current A Do This Turn the 34
13. 30 Specifications 67 79 82 SRO A eee OE Oe vr Rs 4 46 EE EE EEGEN A mask EE oe ee Ea Re 47 Status byte llle 47 58 87 90 Status regiSter o o o o ooo 47 96 Page T Talk only mode 42 Temperature measurement program 54 Test reset 4 29 Trioger iia Hee ee BRA EE 30 53 86 89 external cle 31 indicator cles 30 internal ua FNS hs X Xu XN ee 30 modes ois esseri rre cR d ois 30 A Ex ASEGURO EEN 30 Trouble in case Of 69 TURNING ITON 0 0 0 00 ee ee 4 Two wire ohms measurements 26 U User generated messages 15 V Verification prograM o 70 74 Voltage measurements less 32 Voltmeter Ccomplete 34 W Warranty E Ae eee de A de 72 Product Line Sales Support Key Key Product Line A Analytical CM Components C Computer Systems CP Computer Systems Primary Service Responsible Office SRO CS Computer Systems Secondary SRO E Electronic Instruments amp Measurement Systems M Medical Products MP Medical Products Primary SRO MS Medical Products Secondary SRO P Personal Computing Products Sales only for specific product line Support only for specific product line IMPORTANT These symbols designate general product line capability They do not insure sales or support availability for all products within a line at all locations C
14. A CM CP E MS Hewlett Packard Co 2424 East Aragon Road TUCSON AZ 85702 Tel 602 889 4631 CM CS E MS Arkansas Hewlett Packard Co P O Box 5646 Brady Station LITTLE ROCK AR 72215 Tel 501 376 1844 501 664 8773 CM MS UNITED STATES Cont California Hewlett Packard Co 7621 Canoga Avenue CANOGA PARK CA 91304 Tel 213 702 8300 A CM CP E P Hewlett Packard Co 1579 W Shaw Avenue FRESNO CA 93771 Tel 209 224 0582 CM MS Hewlett Packard Co 1430 East Orangethorpe FULLERTON CA 92631 Tel 714 870 1000 CM CP E MP Hewletl Packard Co 5400 W Rosecrans Boulevard LAWNDALE CA 90260 PO Box 92105 LOS ANGELES CA 90009 Tel 213 970 7500 CM CP MP Hewlett Packard Co 3939 Lankershim Blvd NORTH HOLLYWOOD CA 91604 Tel 213 877 1282 Regional Headquarters Hewlett Packard Co 3200 Hillview Avenue PALO ALTO CA 94304 Tel 415 857 8000 CM CPE Hewlett Packard Co 646 W North Market Boulevard SACRAMENTO CA 95834 Tel 916 929 7222 Ar CM CP E MS Hewlett Packard Co 9606 Aero Drive PO Box 23333 SAN DIEGO CA 92123 Tel 714 279 3200 CM CP E MP Hewlett Packard Co 3003 Scott Boulevard SANTA CLARA CA 95050 Tel 408 988 7000 A CM CP E MP Hewlett Packard Co 454 Carlton Court SO SAN FRANCISCO CA 94080 Tel 415 877 0772 CM CP Colorado Hewlett Packard Co 24 Inverness Place East ENGLEWOOD CO 80112 Tel 303 771 3455 A CM CP E MS Connecticut Hewlett Packard Co
15. NORMAL mode you also have a choice of the number of digits displayed i e resolution of the reading This not only has a great effect on the reading rate but also affects the Normal Mode Re jection NMR Do This press This puts the 3478A into the 3 1 2 digit display mode This mode has the e fastest reading rate but the lowest resolution and little noise rejection The integration time in this mode is 1 i power line cycle OR This is the 4 1 2 digit display mode Bi This mode provides 59 db NMR with Pai an integration time of 1 power line cy cle 16 66 mS at 60Hz 20 mS at 50Hz2 OR The 5 1 2 digit display mode provides 5 the best resolution and greatest 9 amount of noise rejection In this H j mode 10 readings are taken each with 1 power line cycle integration time and averaged together This pro vides 80 db of noise rejection 15 DISPLAY Cont d Integration Times As mentioned above changing the number of display digits does more than merely change the resolution of the multimeter It actually changes the INTEGRATION TIME which determines the reading rate This in turn will greatly affect the Nor mal Mode Rejection NMR of the 3478A The 3478A uses an integration type of A D converter Integration is a process where the effects of line related noise are averaged to zero over the period of an integral number of power line cycles
16. S ON INTR 7 GOSUB 18668 66 EHRBLE INTR 7 8 CB The bod of the Program aa 1000 es here 930 ENO 1808 STATUS 7 1 A 1818 F SPOLL 7233 1426 IF BITCP 4 gt THEN DISP SRG KEY PRESSED 1010 i838 RETURN 1020 1030 49 Description The M20 statement sets the 3478A to respond to the front panel SRO key The K clears the status register except bit O This tells the computer where to go line 1000 when an GRO interrupt occurs ENABLE INTR actually allows the controller to respond to interrupts These lines contain the body of the pro gram Line 1000 is the beginning of the interrupt subroutine The STATUS command reads and clears the hp 85 Status Control register so that it can respond to the next interrupt SPOLL returns 3478A status byte to variable P It also clears the status register Bit 4 of the status byte P is checked to make sure it is a 1 If it is the message SRQ KEY PRESSED is displayed If it isn t then something else caused the interrupt This line returns program control to where it was interrupted SPOLL Example P SPOLL 723 hp 85 STATUS 723 P hp 9835 9845A B Comments Serial poll allows you to determine the current status of the 3478A When the 3478A receives the serial poll message it returns its status byte status register Many controllers will display the byte as the sum of the values of the individual bits that are set If bits 7 and O are set for example
17. Size 102mm H x 215mm W x 356mm D 4 in H x 8 in W x 14 in D Weight 3Kg 6 5 Ibs APPENDIX A Introduction This appendix contains a general description of the Hewlett Packard Interface Bus HP IB HP IB is Hewlett Packard s implementation of IEEE Standard 488 1978 Standard Digital Interface for Programmable Instrumentation The information is non controller dependent but where appropriate is dependent on the 3478A General HP IB Description The Hewlett Packard Interface Bus HP IB is a carefully defined interface which simplifies the integration of various instruments calculators and computers into systems The interface provides for messages in digital form to be transferred bet ween two or more HP IB compatible devices A compatible device can be an in strument calculator computer or peripheral device that is designed to be interfac ed using the HP IB The HP IB is a parallel bus of 16 active signal lines grouped into three sets according to function to interconnect up to 15 instruments Figure A 1 provides a pictorial view of the HP IB connector and its pin designation A diagram of the In terface Connections and Bus Structure is shown in Figure A 2 CAUTION E 5A The 3478A contains metric threaded HP IB cable mounting 3 D103 studs as opposed to English threads Metric threaded hp 4 D104 10631A B or C HP IB cable lockscrews must be used to 13
18. single trigger occurs and if the 3478A is addressed to talk will output the reading This command is equivalent to F1R 2RAZ1N4T3 Measure AC Volts This command is the same as H1 except that an AC Voltage measurement is taken Equivalent to F2R 2RAZ1N4T3 Measure 2 Wire Ohms Identical to H1 except takes a 2 wire ohms measurement Measure 4 Wire Ohms Identical to H1 except takes a 4 wire ohms measurement Measure DC Current Identical to H1 except takes a DC Current measurement Measure AC Current Identical to H1 except takes an AC Current measurement Measure Extended Ohms Identical to H1 except take an extended ohms measure ment 39 Using the Home Commands You can use the HOME commands just as they are or combined with other com mands For example OUTPUT 723 H1 would set the 3478A to the DC Volts function and take one reading If you want the 3478A to be in the internal trigger mode you could send OUTPUT 723 H1T1 In order for T1 to be in effect it must follow the H1 command otherwise the H1 command will put T3 in effect td Programming Hints When more than one command is sent to the 3478A in one OUTPUT instruc tion statement the commands are executed as they arrive Therefore it is best to make the trigger statement the last statement in the command string so that the 3478A will be set up for the measurement before it triggers If you send the com mand T3T1 the T1
19. tallisgatan 30 S 42132 VASTRA FROLUNDA Tel 031 49 09 50 Telex 854 10721 via BROMMA office CM CS E P SWITZERLAND Hewlett Packard Schweiz AG Clarastrasse 12 CH 4058 BASLE Tel 61 33 59 20 A CM Hewlett Packard Schweiz AG 47 Avenue Blanc CH 1202 GENEVA Tel 022 32 30 05 32 48 00 CM CP Hewlett Packard Schweiz AG 29 Chemin Ch teau Bloc CH 1219 LE LIGNON Geneva Tel 022 96 03 22 Telex 27333 hpag ch Cable HEWPACKAG Geneva A CM E MS P Hewlett Packard Schweiz AG Z rcherstrasse 20 Allmend 2 CH 8967 WIDEN Tel 57 50 111 Telex 59933 hpag ch Cable HPAG CH A CM CP E MS P SYRIA General Electronic Inc Nuri Basha Ahnat Ebn Kays Street DO Box 5781 DAMASCUS Tel 33 24 87 Telex 11215 ITIKAL Cable ELECTROBOR DAMASCUS E Sawah amp Co Place Azm Boite Postale 2308 DAMASCUS Tel 16 367 19 697 14 268 Telex 11304 SATACO SY Cable SAWAH DAMASCUS M TAIWAN Hewlett Packard Far East Ltd Kaohsiung Branch 68 2 Chung Cheng 3rd Road Shin Shin Chu KAOHSIUNG Tel 24 2318 26 3253 CS E MS P Hewlett Packard Far East Ltd Taiwan Branch 5th Floor 205 Tun Hwa North Road TAIPEI Tel 02 751 0404 Cable HEWPACK Taipei A CP E MS P Hewlett Packard Far East Ltd Taichung Branch 33 Cheng Yih Street 10th Floor Room 5 TAICHUNG Tel 289274 Ing Lih Trading Co 3rd Floor 18 Po la Road TAIPEI Tel Telex Cable INGLIH TAIPEI A THAILAND UNMESA C
20. 0 000000 4 11 Annunciators dei a a 17 ASCII character Set o 91 AUTOFANGe rai at ae 4 21 hySteresis c ad eh ern TE 21 AUTOZO O m uA uie Sele ee ah we ive tobe 4 8 19 C Calibration o 4 10 ALE A IN 74 CLEAR uo ie eto Beck We ok PS 43 86 90 Clear Lockout Set Local 44 86 90 Current measurements 00 11 D Data BEER 86 89 MOSSADO Sonn popoi Par EEN 37 ready SROs solus ee oe a 48 dBm measurement prograM 56 DC CUTTERE mari Su Oe AS LEG b e Wes 11 VOltS iy es MAP he hale dd cable EC Tos 32 Display v aw a E E IER 4 12 20 digits 5s Sete os RA ee a 4 15 ue EECHER 13 29 normal dXXd ue d der de 12 user generated messages 15 F Environment environmental requirements 67 signal eNvVironMentS 18 Extended OAhMS 26 55 External Trigger o 31 F Format output llle 42 Four wire ohms measurements 26 Front rear switch 0 0 4 Fuse replacement 000 4 68 95 Page H Hints programming 40 Home Commandes 39 see also Table 3 1 and Quick Reference Guide HP IB general description 5 83 interface connections 67 83 program Codes eeu ae 59 WOTKSHe t o o oo 83 Input terminals 0200000008 4 Integration ls ERUN aw 16 18 Internal trigger
21. 057 47 o 01001111 117 79 o 01101111 157 111 DLE 00010000 020 16 0 00110000 060 48 P 01010000 120 80 p 01110000 160 112 DC 00010001 021 17 1 00110001 061 49 a 01010001 121 81 q 01110001 161 113 DC 00010010 022 18 2 00110010 062 50 R 01010010 122 82 r 01110010 162 114 DC 00010011 023 19 3 00110011 063 51 S 01010011 123 83 s 01110011 163 115 DC 00010100 024 20 4 00110100 064 52 T 01010100 124 84 t 01110100 164 116 NAK 00010101 025 21 5 00110101 065 53 U 01010101 125 85 u 01110101 165 117 SYNC 00010110 026 22 6 00110110 066 54 v 01010110 126 86 v 01110110 166 118 ETB 00010111 027 23 7 00110111 067 55 w 01010111 127 87 w 01110111 167 119 CAN 00011000 030 24 8 00111000 070 56 x 01011000 130 88 x 01111000 170 120 EM 00011001 031 25 9 00111001 071 57 Y 01011001 131 89 Y 01111001 171 121 SUB 00011010 032 26 i 00111010 072 58 z 01011010 132 90 z 01111010 172 122 ESC 00011011 033 27 00111011 073 59 I 01011011 133 91 01111011 173 123 FS 00011100 034 28 lt 00111100 074 o 01011100 134 92 01111100 174 124 GS 00011101 035 29 00111101 075 61 01011101 135 93 01111101 175 125 RS 00011110 036 30 gt 00111110 076 62 01011110 136 94 01111110 176 126 US 00011111 037 31 00111111 077 63 gt 01011111 137 95 DEL 0111111 177 127 91 92 Function Code Autorange DC Volts F1 30mV 300mv 3V 30V 300V AC Volts F2 300mv 3V 30V 300V 2 W Ohm F3 3002 30002 3KQ S3OKQ 300kQ 3MQ 30MQ 4 W Ohm F4 i bi 3
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23. 20kHz 0 29 163 0 26 102 0 33 102 20kHz 50kHz 0 56 247 0 41 180 0 55 180 Maximum Input Voltage non destructive 5OkHz 100kHz 1 74 882 1 05 825 1 26 825 100kHz 300kHz 10 1 3720 Hi to Lo 303Vrms or 450V peak 30V range only Hi or Lo to Earth Ground 500V peak 80 Table 4 3 Specifications Cont d AC VOLTAGE true rms responding Cont d Auto Zero Off 5 digits for a stable environment 1 C for lt 24 hrs counts to accuracy specifications for all ranges add 10 Temperature Coefficient O C to Cal Temp 5 C Cal Temp 4 5 C to 55 C 5 digit display auto zero ON For frequencies lt 20kHz 0 01696 of reading 10 counts C For frequencies gt 20kHz x 0 0496 of reading 10 counts C Crest Factor gt 4 1 at full scale Common Mode Rejection With 1kQ imbalance in Lo lead gt 70dB dc to 60Hz Maximum Reading Rates readings sec First reading is correct within 70 counts of final value when on Correct range triggered coincident with step input Add O 6 seconds for each range change Reading rates are the same as dc volts using fast trigger T5 Using Nor mal Trigger T1 T2 T3 For 50 or 60Hz operation auto zero ON or OFF 3 or 4 digits 1 4 5 digits 1 0 RESISTANCE 2 wire Q 4 wire Q Input Characteristics 2 Wire Ohms Accuracy Maximum Same as 4 wire ohms except add a maximum of 100m off
24. 3478A DO NOT PRESS ANY 3478A KEYS DURING THIS TEST UNTIL INSTRUCTED TO DO SO REMOVE ALL INPUT CABLES FROM THE 3478R TEST PROGRESS IS SHOWN ON THE DISPLAY ERRORS ARE NOTED ON THE PRINTER PRESS ECONTI KEY TO BEGIN HP IR Description Appendix A HP IB is Hewlett Packard s implemen tation of JEEE standard 488 1978 Standard Digital Interface for Program mable Instrumentation Appendix A provides a general description of the HP IB Interface This information is controller independent but gives specific information about the 3478A as it relates to HP IB Turning it On Before applying ac power to the 3478A check the rear panel line voltage option label to be certain the instrument is set for the nominal line voltage in your area If necessary refer to the installation information in Chapter 4 As you press the line switch carefully watch the display as the 3478A goes through a complete internal self test and displays its HP IB address DISPLAY NOTE RESULT The 3478A displays SELF TEST during the period of time it is perform ing the tests It will then display SELF TEST OK or an appropriate error message upon completion of the Self Test The message shown here affirms that the 3478A is ready for measurements The factory preset HP IB address for the 3478A is 23 This address may be easily changed to fit your system needs by means of five switches on the rear panel The 3478A may
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26. D105 secure the cable to the instrument Identification of the two 14 D106 types of mounting studs and lockscrews is made by their color 15 D107 English threaded fasteners are colored silver and metric thread Si ed fasteners are colored black DO NOT mate silver and black e REN fasteners to each other or the threads of either or both will be 6 DAV destroyed Metric threaded HP IB cable hardware illustrations 7 NRFD and part numbers follow a a LOCKSCREW LONG MOUNTING STUD SHORT MOUNTING STUD 10 sra 1390 0360 0380 0643 0380 0644 11 ATN x 12 SHIELD CHASSIS GROUND 18 P O TWISTED PAIR WITH PIN 6 1 19 P O TWISTED PAIR WITH PIN 7 THESE PINS 20 P O TWISTED PAIR WITH PIN 8 ARE 21 P O TWISTED PAIR WITH PIN 9 INTERNALLY 22 P P TWISTED PAIR WITH PIN 10 BOUNDED 23 P O TWISTED PAIR WITH PIN 11 24 ISOLATED DIGITAL GROUND Figure A 1 HP IB Connector 83 IT DEVICE A ABLE TO TAK LISTEN AND CONTROL AAT X te q CALCULATOR E i gt DATA BUS WE 18 S Gi iNES eebe er Ah 2 fide lila A See EE DEvICE B AB_ TO TALK AND LISTEN H ERE E Ir Ar i EH I el it D SS e g DIG TAL VOLTMETER i DATA BYTE TRANSFER CONTRO Seege a E iHANOSHAKE 1 NES 3 S GNAL LINES Y gt DEVICE C ONLY ABLE TO LISTEN 7 LA 4 ONIS e g SIGNAL GENERATOR y TIT PN Li GENERAL INTERFACE MANAGEMENT 15 GNAL LINES MANAGE
27. Devices which communicate along the interface bus can be classified into three basic categories a Talker Any device that is able to send information over the HP IB when it has been addressed Only one talker may be active at a time usually the one that is currently directed to send data All HP IB type calculators and computers are generally talkers b Listener Devices which receive information over the HP IB when they have been addressed A device may or may not be both a talker and a listener Calculators and computers are generally both a talker and a listener at different times 85 c Controller The device that can specify which device s on the bus is a talker or listener There can be two types of controllers an Active Controller and a System Controller The Active Controller is the current controlling device The System Controller can however take control of the HP IB even if it is not the Ac tive Controller There can also be only one Active Controller at a time even if several controllers are on the Bus HP IB Messages Different types of information can be passed over the HP IB to one or more devices Some of this inforamtion is in the form of messages most of which can be separated into two parts One part can be classified as the address portion specified by the controller and the information that comprises the messages The second part can be classified as HP IB management messages These message are comprised of
28. EOI X X X T X Abort Message To send the ABORT Message Bus Management Lines ATN IFC SRQ REN EOI X T X X X ASCII Character Codes ASCII EQUIVALENT FORMS ASCII EQUIVALENT FORMS ASCII EQUIVALENT FORMS ASCII EQUIVALENT FORMS Char Binary Octal Dec Char Binary Octal Dec Char Binary Octal Dec Char Binary Detal Dec NULL 00000000 000 o space 00100000 040 32 01000000 100 64 01100000 140 96 SOH 00000001 001 1 00100001 041 33 A 01000001 101 65 a 01100001 141 97 STX 00000010 002 2 s 00100010 042 34 B 01000010 102 66 b 01100010 142 98 ETX 00000011 003 3 D 00100011 043 35 c 01000011 103 67 c 01100011 143 99 EOT 00000100 004 4 00100100 044 36 D 01000100 104 68 d 01100100 144 100 ENQ 00000101 005 5 96 00100101 045 37 E 01000101 105 69 e 01100101 145 101 ACK 00000110 006 6 amp 00100110 046 38 F 01000110 106 70 f 01100110 146 102 BELL 00000111 007 7 00100111 047 39 G 01000111 107 71 g 01100111 147 103 BS 00001000 010 8 00101000 050 40 H 01001000 110 72 h 01101000 150 104 HT 00001001 011 9 00101001 051 41 1 01001001 111 73 i 01101001 151 105 LF 00001010 012 10 00101010 052 42 J 01001010 112 74 j 01101010 152 106 Vrag 90001011 013 11 00101011 053 43 K 01001011 113 75 k 01101011 153 107 FF 00001100 014 12 00101100 054 44 L 01001100 114 76 01101100 154 108 CR 00001101 015 13 00101101 055 45 M 01001101 115 77 m 01101101 155 109 so 00001110 016 14 00101110 056 46 N 01001110 116 78 n 01101110 156 110 Si 00001111 017 15 00101111
29. TLK annunciator means that the 3478A has been addressed to talk via the HP IB RMT RMT indicates that the 3478A is under bus control that is it is under remote operation The front panel keyboard is inactive except for the LOCAL and SRQ keys see LOCAL and LOCAL LOCKOUT in the next chapter MATH MATH is not used on the 34784 AZ OFF The Autozero feature of the 3478A is disabled 20 The 3478A is in the 2 wire ohms mode 4Q The 3478A is in the 4 wire ohms mode M RNG This annunciator indicates that the 3478A is in the manual ranging mode auto range is inactive S TRIG Single trigger means that the internal trigger is disabled The voltmeter idles until either an external trigger pulse is received the single trigger key is pressed again or a TRIGGER message is received over the Bus CAL The CAL annunciator will blink if the 3478A requires calibration in the selected range and function SHIFT This annunciator indicates that the SHIFT key has been pressed enabling the shifted functions The annunciator will go off when either the function is executed or the SHIFT key is pressed again 17 OPTIMIZING READING RATES Why Optimize There are several reasons why you would want to optimize the rate at which readings are taken by the 3478A Perhaps you are using a scanner to measure a large number of points where a faster reading rate would mean a better picture of what is happening at a single point in time Or maybe you n
30. above Figure 3 2 Instruction Example As you can see from the example more than one instruction may be sent to the 3478A at one time any number of instructions may be included in the command string In the next section we will look at the HOME commands of the 3478A Each HOME command is actually made up of several instructions But for now let s take another look at using multiple instructions Sample Problem We want to make an ac voltage measurement that we know to be between 20 volts and 1 volt We also want Autozero on and the measurement to be made in the 4 1 2 digit mode What series of instructions will achieve this First it is an ac voltage measurement therefore instruction F2 Function 2 is used We don t know exactly what range to use so let s use the autorange feature RA Range Auto The instruction for autozero on is 21 Zero 1 and for the 4 1 2 digit mode N4 Number of digits 4 Our com mand string now looks like F2RAZ1N4 38 Since we know the voltage to be measured is small let s set the 3478A to a low range before we autorange The instruction R 2 Range 2 will do this for us Furthermore if we want the meter to only take one reading we could add the instruction T3 Trigger mode 3 to the end of the string By adding it at the end the meter is set up for the measurement before the reading is actually trig gered The complete string along with the OUTPUT statement is
31. also be set for TALK ONLY in which case the display would indicate HPIB ADRS T O Note if the self test does not pass this message would be replaced by an error message This entire process takes only a moment to complete At this point the 3478A is ready to use and is set to the following state Function DC Volts Range Autorange on Display 5 1 2 Digits of Display Trigger Internal Trigger Auto zero On Most 3478A s produced prior to January 1983 will not display SELF TEST OK Test Reset Even though the 3478A went through its Self Test during Turn on let s go through it manually As we do carefully watch the display especially the 12 annunciators along the bottom Every segment in the display except for the top dot in the colon is turned on for as long as you hold the Self Test button down When the button is released the display will remain for approximately 2 seconds while the Self Test is performed The 3478A is then reset and returns to its turn on state A more complete description of the Self Test is found in Chapter Il Should any of the five elements of the self test fail a message will be displayed identifying the general circuit area where the failure occurred This can greatly reduce initial troubleshooting time Do This DISPLAY RESET TRIG L E NOTE Most 3478A s produced prior to January 1983 will turn on every display segment for the duration of the Self Test ap proximatel
32. as two octal digits followed by a CR LF The E command also clears the Error Register Set the SRQ Mask to octal value xx The parameter xx must be two digits exact ly Bits O through 5 of the binary representation of xx are used to set the ap propriate mask bits Return the Front Rear switch position If the 3478A is addressed to talk after receiving the S command it will output either a 1 or a O CR LF depending on whether the front rear switch was in the front or rear position respectively The position of the switch is read only when a reading is taken and thus returns the position of the switch at time of the last reading Calibrate Calibrate See the 3478A Service Manual 62 Chapter IV Operators Maintenance Introduction Your 3478A Digital Multimeter was thoughtfully engineered for ease of use ac curacy and perhaps most important reliability The instrument was carefully in spected before shipping and should be free of mechanical and electrical flaws and should be in proper electrical working condition The information in this chapter covers the initial setup and installation of the 3478A and should be read before the 3478A is installed for use This chapter also includes the specification table warranty information instructions about what to do if you suspect the multimeter is malfunctioning obtaining repair service cleaning etc Table 4 1 lists the available accessories for your 3478A
33. designated by hp Buyer shall prepay shipping charges to hp and hp shall pay shipping charges to return the product to Buyer However Buyer shall pay all ship ping charges duties and taxes for products returned to hp from another coun try Hewlett Packard warrants that its software and firmware designated by hp for use with an instrument will execute its programming instructions when properly in stalled on that instrument Hewlett Packard does not warrant that the operation of the instrument or software or firmware will be uninterrupted or error free Limitation of Warranty The foregoing warranty shall not apply to defects resulting from improper or inade quate maintenance by Buyer Buyer supplied software or interfacing unauthorized modification or misuse operation outside of the environmental specifications for the product or improper site preparation or maintenance NO OTHER WARRANTY IS EXPRESSED OR IMPLIED HEWLETT PACKARD SPECIFICALLY DISCLAIMS THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 73 Exclusive Remedies THE REMEDIES PROVIDED HEREIN ARE BUYER S SOLE AND EXCLUSIVE REMEDIES HEWLETT PACKARD SHALL NOT BE LIABLE FOR ANY DIRECT IN DIRECT SPECIAL INCIDENTAL OR CONSEQUENTIAL DAMAGES WHETHER BASED ON CONTRACT TORT OR ANY OTHER LEGAL THEORY Assistance Product maintenance agreements and other customer assistance agreements are available for Hewlett Packard produc
34. hardware error occurs Bit 2 1 then SRQ if syntax error occurs Bit 1 not used Bit O 1 then SRQ as every reading is availabe to the bus 61 3478A Programming Commands Cont d me commons ein Binary Status Byte 4 Error Information Cont d Bit 7 Always zero Bit 6 Always zero Bit 5 1 then There has been a failure in the A D link Bit 4 1 then The A D has failed its internal Self Test Bit 3 1 then There has been an A D slope error Bit 2 1 then The ROM self test has failed Bit 1 1 then The RAM self test has failed Bit O 1 then This bit is set by the self test routine if any of the CAL RAM locations have bad checksums or if a range with a bad checksum is selected Byte 5 DAC Value This byte will contain a value between O and 63 decimal This represents the setting of the internal Digital to Analog Converter DAC and is primarily for diagnostic purposes Clear the Serial Poll Register This command clears bits 1 5 and 7 in the Serial Poll Register Bit O always represents the current status and is unaffected by this command Bit 6 is either set 1 or cleared 0 depending upon the binary AND of bit O in the status register and the SRQ mask Bit 6 is reset by a Serial Poll Error Register This command enables the controller to read the 3478A Error Register See Byte 4 in the B command above for an explanation of this register Unlike the B command the E command outputs the Error Register
35. higher resistance ranges Ideally the test leads should be a shielded twisted pair to reduce noise pick up 2 For best results especially at 3 1 2 digits display the input LO terminal should be connected to the 3478A chassis earth ground 3 Additional settling time may be required when using the higher ohms ranges under program control This is important if there is more than 200pF shunt capacitance connected externally as might be the case if you were using the 3478A with a scanner Theoretically the settling time necessary is RC In P 100 Where R is the resistance being measured C is equal to 620pF plus any external capacitance and P is the desired percentage of step accuracy For example lets say we want to measure a 3 0 Mohm resistor through a scanner with 1200pF capacitance High to Lo terminals If a short was previously applied short to 3 0 Mohms step and a 00196 reading is desired the settling time necessary is 3 108 1200 620 10 12 In 001 100 63mS Since on the 3 Mohm range there is an internal delay of 30mS an additional delay of 30 to 35 mS should be allowed The 30 Mohm range has an internal delay of 300 mS 28 TEST RESET What it Does The 3478A self test performs several checks on the digital and A D converter cir cuitry of the instrument A failure in any of these four areas is indicated by an er ror message in the display When the self test is complete the 3478A reset
36. illustrate the flexibility and measurement power of the 3478A The programs include using a thermistor to accurately measure temperature achieving the maximum reading rate using the 3478A Status Bytes and more Although the programs were developed on an hp 85 desktop com puter they may easily be modified to run on any other controller In many cases suggestions are made for modifying the programs to suit your individual needs TEMPERATURE MEASUREMENTS The program shown in the following figure computes the temperature in C cor responding to the resistance of a thermistor The program has been designed to work with thermistors exhibiting a 5 000 KQ resistance at 25 C such as a type 44007 hp part number 0837 0164 or equivalent The program gives you the option of selecting either 2 wire or 4 wire ohms measurements to be made on the thermistor As it stands the program sets the 3478A for a 2 wire measurement which gives suitable results if the thermistor is used at a temperature where its resistance is much greater than the resistance of the test ieads For greatest accuracy from a thermistor a 4 wire resistance measurement should be used To change to a 4 wire resistance measurement delete the exclamation mark from line 50 The program is useful over a temperature range of 80 C to 150 C Lines Description 40 50 Line 40 sets the 3478A up for a 2 wire resistance measurement on the thermistor TEMPERATURE MEASUREMENT The 3
37. terminals are selected Try this program with the switch in both positions If the 3478A is in the single trigger mode S TRIG annunciator on this program will not work Either press LOCAL INT TRIG keys or reset the voltmeter 41 Output Format Messages are sent by the 3478A as 13 bytes in the following formats Voltmeter Reading d dddddE d CR LF Overload 9 99999E 9 CR LF The character d represents a single digit If the 3478A is in the 4 1 2 digit mode the last digit returned before the E will be a O In the 3 1 2 digit mode the last 2 digits will be O s 3478A Bus Capabilities So far we have seen how to program the 3478A for specific operations and how to read back the data But now it is time to move on and look at special HP IB commands and advanced programming topics Talk Only Mode Many applications of the 3478A a simple data logger for example may require that the instrument take readings and output them to some device such as a printer All this is to be done without the aid of a controller The 3478A s TALK ONLY mode allows just that type of transaction to occur The 3478A is set to the talk only mode by setting the 5 HP IB address switches on the 3478A rear panel to the 1 up position Refer to Chapter 4 Measure ment data is output after each completed reading Function and range settings etc are done from the front panel keyboard 3478A Response to Bus Messages The following topic
38. the Bus There can be only one instrument addressed to talk on the Bus at any one time 36 Sending instructi ha Ac d bd A De 64 735A ne ns io e The Instruction Message is one specific form of an HP IB Data message see Ap pendix A It is used to cause the 3478A to change states i e make an ac measurement instead of a dc measurement or perform a particular operation such as output status information etc Look at the blue pages at the end of this chapter They describe each of the Instruction Messages the 3478A will respond to and how they are used An abbreviated table is given in the Command Quick Reference Guide Look at Figure 3 1 The instruction message may contain from one to three parts as shown the Operation Mnemonic Qualifier and Data The Operation Mnemonic is a single letter which is always used The Qualifier and Data portion of the message are used as defined by the operation to be performed An example of a command which requires only the operation mnemonic is the S command A function or range command requires the mnemonic plus a qualifier e g F2 or R 1 The D2 or D3 commands require the mnemonic D a qualifier either 2 or 3 and data which is the text to be displayed The diagram also shows that instructions may be linked together forming a string of instructions Note 1 Note 1 The computer or controller output command as shown in the figure in cludes the HP IB address of th
39. the display 40 Receiving Data from the 3478A The 3478A has the ability to talk to the computer or other instruments giving the results of measurements or status information This is another specific form of the HP IB Data Message The controller must tell or address the 3478A to talk in order for it to send data Example From the last section we saw how to make the voltmeter go to the DC Volts function and 30V range Now we will see how to read back the measured voltage 10 OUTPUT 723 F1R1 from the last section 20 ENTER 723 A 30 DISP A 40 END The 3478A is addressed to talk by the ENTER 723 command in the second line The measurement result is stored in the string variable A and displayed on the controller s display Remember that the actual computer syntax used e ENTER OUTPUT DISPLAY etc is dependent on the computer that you are using and may be different than the examples given You should refer to your computer s I O programming manual Let s try another very simple example You can use your controller to determine the setting of the 3478A s Front Rear switch This is done by sending the pro gram command S and then reading the output Do This Enter the following program and run it 10 OUTPUT 723 S 20 ENTER 723 S1 30 DISP S1 40 END If the value read back from the 3478A variable S1 in the example shown is 0 the rear panel terminals are selected If the value is 1 the front panel
40. the test leads is not critical Inaccurate results may occur when using the 2 wire ohms mode if the resistance of the test leads is very high i e long test leads Suppose you are making temperature measurements with a type 44004 thermistor Refer to Figure 2 4 At 20 C 40 feet of 24 A W G copper wire has a resistance of 1 02 ohms Two such wires would have a total resistance of 2 04 ohms With a type 44004 thermistor this would result in an error of 1 DESIGNED FOR LX Command SYSTEMS F3 Selects 2 wire ohms mode also H3 4 Wire Ohms The use of 4 wire ohms measurements alleviates the errors caused by the effects of test lead resistance Figure 2 4 illustrates this point The current through the thermistor is the same regardless of the lead resistance and the voltmeter measures only the voltage across the thermistor not across the combined lead resistance The 4 wire resistance measurements are essential when highest ac curacy is required or where long lead lengths are present DESIGNED FOR GES Command SYSTEMS F4 Selects 4 wire ohms mode also H4 Extended Ohms The extended ohms feature of the 3478A is available only via the F7 remote pro gramming command With extended ohms the 3478A can be used to measure resistances in excess of 30 Mohms When in the extended ohms mode the 3478A goes to the 30 Mohm range 2 wire mode An internal resistance of ap proximately 10 Mohms is placed in parallel with the input t
41. the value would be shown as 129 129 128 1 The 8 bits of the status byte and their respective values are shown in Figure 3 5 followed by a description of the bits Bit 7 Bit 3 Bit 1 Bit 5 Cal Failed N A always 0 Hardware Error power on Reset SRG Decimal Value 128 64 32 4 2 Figure 3 5 Status Byte Data Ready When this bit is set to 1 it indicates that the 3478A will out Bit O put a reading if it is addressed to talk This bit will return to O when the controller begins to accept the reading or when some change in the programmed state of the 3478A causes the reading to be no longer available Bit 1 This bit is always O Syntax Error When set to 1 this bit indicates that a command has been Bit 2 received over the HP IB that is syntactically incorrect Hardware Error This bit when it is set to 1 indicates that a hardware error of Bit 3 some sort has occurred This may be the failure of a self test routine a problem with the A D converter or a checksum error in the calibration RAM More information can be obtained about the error by reading the 3478A error register see the B and E bus commands The calibration RAM checksum is checked every time a reading is made 50 SPOLL Cont d Front Panel SRQ When this bit is set to a 1 it indicates that the front panel Bit 4 SRQ button has been pressed Calibration Fail This bit is used to indicate that an attempted calibratio
42. this chapter is divided into 12 major subject headings Each subject presents the most com prehensive information about a particular feature or function of the 3478A At the end of most subjects will be a short list of HP IB remote programming commands that pertain to that subject For more information on remote programming refer to Chapter III Operating Characteristics The Operating Characteristics of the 34784 are detailed in Table 2 1 This table is not the comprehensive table of specifications but rather an abbreviated set You will probably find that this table answers most of your questions about the capabilities of the multimeter without poring over several pages of specifications Should you ever need to refer to them the complete Table of Specifications for the 3478A is given in Chapter 4 Table 2 1 Operating Characteristics DC VOLTS 100 nanovolt resolution 30mv range to 300V AC AMPS 14A resolution 300mA range to 3A Full Scale Full Scale Maximum Shunt Resistance 3Q Zin gt 10199 30mV 300mV and 3V range Maximum Burden at Full Scale lt 900mV 10 MQ 1 30V and 300V range Bandwidth 20Hz 20kHz AC VOLTS 14V resolution 300mV range to 300V full OHMS 10040 resolution 30 ohm range to 30 scale True RMS Responding Crest Factor megohms Full Scale 4 1 at full scale Open Circuit Voltage lt 6 3V Bandwidth 20Hz to 100KHz 300KHz on 30V Current through Rx 300 3009 3K range 1mA range 30KQ range 100A Zin 1 MQ
43. volts It should be apparent that the multimeter is in the 300 milli volt range the reading is too large to be read on the 30 milli volt range 20 RANGING Cont d Table 2 4 Valid 3478A Ranges DC Volts 30mV 300mV R 2 R 1 3V 30V 300V RO R1 R2 AC Volts 300mV R 1 3V 30V 300V RO R1 R2 DC Current 300mA R 1 3A RO AC Current 300mA R 1 3A RO Resistance 302 3000 R1 R2 3KQ 30KQ 300KQ R3 R4 R5 3MQ 30MQ R6 R7 If the multimeter is in the manual range mode the display will indicate an OVLD when the input is greater than the particular range can handle R 2 selects the most sensitive range on any function Autorange Autoranging on the 3478A is done by taking readings in the 4 1 2 digit mode on successive ranges until it finds the proper range that will allow for a display bet ween full scale 303099 counts and approximately 996 of full scale 027000 counts DESIGNED FOR GLA Command SYSTEMS RA Selects autorange mode Autorange Hysteresis In the autorange mode the multimeter will up range go to a higher range if the display reading exceeds 303099 counts or it will down range go to the next lower range if the display reading decreases below O27000 counts This assumes a 5 1 2 digit mode These numerical autorange points are irrespective of decimal point placement The difference between the two points is called the autorange hysteresis and is illustrated in Figure 2 2 for DC Volts Autoranging
44. 002 3002 3KQ2 30KQ 300KQ 3MQ 30MQ 300mA 3A 300mA 3A DC Amps FS AC Amps F6 Enhanced F7 Ohms Notes indicates that the range code selects the lowest most sensitive range for that function indicates that the range code selects the highest least sensitive range for that function Other Program Codes Function Mnemonic Qualifier Description Example Selects the number of digits of display N3 selects the 3 1 3 digit display T2 selects external trigger Trigger mode Internal External Single Hold Fast ZO turns Autozero off Z1 turns Autozero on Autozero Display D1 selects normal display D2text prints message text on display Home preset HO F1T4R 2RAZ1N4 H1 F1R 2RAZ1N4T3 H2 F2R 2RAZ1N4T3 H3 F3R 2RAZ1N4T3 H4 F4R 2RAZ1N4T3 H5 F5R 2RAZ1N4T3 H6 F6R 2RAZ1N4T3 H7 F7R 2RAZ1N4T3 Output Binary status Calibrate see service manual Ciear serial poll register read and clear error register O to 77 octal Set SRQ mask to octal value xx Return value of Front Rear switch 93 94 Page A ABORT mMessagle 87 91 Abnormal multimeter readings 13 ACCOSSOMES ates VE V RUE Re A 83 AC CUIFENT amp sss sos La Ya sore v Y va s 11 VENU 32 Address HP IB 4 36 37 68 Amps terminal
45. 07 3 0 0004 3 0 019 3 First reading is correct within 1 count of final value when on 300 v 0 008 2 0 020 2 0 019 2 correct range triggered coincident with step input 4 and 3 Digit Mode The reading rates are dependent on the speed of the controller being used Accuracy is the same as 5 digit mode for 96 of reading use 1 count for number of counts on all ranges except 30mV Line Auto Resolution range use 4 counts Frequence i Zero E 3 Digits 4 Digits 5 Digits A E The Cal Temp Calibration Temperature is the temperature off 71 33 44 of the environment where the 3478A was calibrated Cali 60Hz On 53 20 i 2 3 bration should be performed with the temperature of the i i environment between 20 C and 30 C Off 67 30 37 50Hz On 50 t 17 f 1 9 AC VOLTAGE true rms responding Input Characteristics Measurement Accuracy Maximum y t 96 of reading number of counts Reading Resolution Auto zero ON 5 eg Ge get is specified for sine 5 Digi ini 4 Digit ini wave inputs only gt 1096 of full scale Range i Digit 5 Digit Ji Digi 3 Digit 1 Year Cal Temp 5 C 300mV 303 099mV 1V 104V 100V 3 V 3 03099 V 10V 100V 1mV 30 V 30 3099 V 100V 1mV 10mV Ranges 300 v 303 099 V 1mV 10mV 100mV rumm 39 3V 30V p mm Input Impedance 20Hz 50Hz 1 144163 114 102 1 18 102 50Hz 100Hz 0 46 163 0 46 103 0 5 102 1MQ 1 shunted by 6OpF 100Hz
46. 1 1 23 Factory Default Select Codes can 8 X 1 1 o 9 o 24 9 Y c os 1 0 0 1 25 be any integer 1 F z 1 1 o 1 o 26 thru 12 Primary 1 1 0 1 1 27 Addresses can be d Cl 1 1 o 0 28 any integer O thru 1 1 1 o 1 29 30 31 is not a i i valid HP IB ad gt SN s e E o a0 Talk Only 1 1 1 1 1 dress Figure 4 3 3478A Address Codes 69 In Case of Trouble If at any time you suspect that the 3478A is malfunctioning perform the self test as follows ge RESET TRIG This initiates the functional self test of the 3478A The self test starts by turning on every segment in the display except the top dot on the colon for about 2 seconds Following this the self test actually begins with any discrepancies noted in the display If there are no self test failures the HP IB address is displayed and the 3478A returns to its power on state The following is a list of possible self test failures U C RAM FAIL This indicates the internal microcomputer U C RAM not CAL RAM has failed its self test U C ROM FAIL The 3478A has failed its internal ROM self test UNCALIBRATED The RAM that contains the calibration constants has an incorrect checksum the calibration of the 3478A is suspect A D TEST FAIL The A D converter has failed its self test A D LINK FAIL The microprocessor cannot communicate with the A D converter If the Voltmeter self test fails or the display is blank or it will
47. 1040 48 Description Outputs the SRQ mask The K com mand clears the status register except bit O Instructs the computer where to go line 1000 when an interrupt SRQ occurs on interface 7 ENABLE INTR7 8 actually enables the hp 85 to respond to the SRQ SRO is oc tal code 8 in the hp 85 control register These lines contain the main body of the program This is the start of the interrupt subroutine SPOLL returns the 3478A status byte to variable P It also resets bit 6 if it was set of the status register The STATUS command reads and clears the hp 85 Status Control register so that it can respond to the next interrupt Line 1010 reads the data and resets bit O of the status register Line 1020 displays the data Line 1030 returns program con trol to where the program was interrupted Example 2 Front Panel SRO The front panel SRO feature of the 3478A provides you with a way of manually interrupting the controller from the multimeter front panel This feature is enabled by setting bit 4 of the SRQ mask command M20 Once this is done pressing the 3478A front panel SRO key causes the 3478A to request service SRQ from the controller The SRQ annunciator turns on in the display until the controller responds by doing a serial poll or the CLEAR command or K instruction Line 40 50 18 1 FRONT FAHEL SRG EXAMPLE 60 28 he 85 VERSION 38 3478A AT RDDRESS 72Z 49 OUTPUT 723 KMz a 70 990
48. 3 BIT B3 75 BIT UQB3 652 BITCBS3 55 BITCB3 45 B ITCB3 32 BITCB3 25 BITCEG 13 BITEB3 80 DISP BYTE 4 BITCB4 79 BIT 64 6 BIT B4 5 BITCB4 459 58 IT B4 S39 BITCR4 23 BITCB4 13 iBITCB4 0 DISP BYTE 5 BIT4BS5 725 BIT C65 6 BITCBS SG BITCBS 4158 ITE BS5 205 BITCB5 25 BITCBS5 19 BITE B5 85 ENG rea SCiB gt Bi 2478A STATE PROGRAM he 85 VERSION 3478A ADDRESS Fes F OUTPUT 723 B ENTER 23 USING S 1B gt El IF BITC B1 7 5 THEN F 4 IF BITCB1 6 gt THEN F F 2 IF BITCB1 5 gt THEN F F i IF F 1 THEN G DC VOLTS IF F 2 THEN G AC VOLTS IF F 3 THEN G 2 WIRE OHMS IF F 4 THEN G 4 WIRE OHMS IF F 5 THEN G DC AMPS IF F 6 THEN G AC ANPS IF F THEN G EXTEHDED OHM ga PRINT PRINT FUNCTION 6 END Lines 40 50 60 100 lines 40 50 60 70 90 100 160 170 180 58 Status Bytes Program Description The B command instructs the 3478A to output its five status bytes The five bytes are entered into variables B1 through B5 Each line displays the individual bits of one byte Measurement Function Program Description Line 40 sets up variable F As in the other program these two lines call for the status bytes The three highest bits of byte 1 are tested and F is valued accordingly The value of F is tested and G assigned The value of G is printed 3478A Programming Commands Measurement Func
49. 478A Service Manual Resistances in excess of 30 Megohms may be measured using the extended ohms mode remote operation only see Chapter 3 How Resistances are Measured Resistances are measured by the 3478A sourcing a known current through the unknown resistance A dc voltage measurement is made across the resistance The value of the resistance can then be determined Ohm s Law Resistance Voltage Current Figure 2 4 shows the current source and the voltmeter connec tions for both 2 and 4 wire ohms measurements Table 2 5 shows the nominal cur rent through the unknown resistance for the individual ohms ranges Variations in cur rents are compensated for by the calibration constants Table 2 5 Nominal Currents through Unknown Resistance Current Through Maximum Open Unknown Circuit Voltage There are two situations in which the 3478A may indicate a negative minus resistance either small negative voltages may exist on the circuit under test or the inputs to the 4 WIRE SENSE and the INPUT leads are inverted from each other in the 4 wire ohms function In the 5 digit mode the 3478A may show 10 counts or more of noise on the 30 ohm and 30 Megohm ranges If the 3 digit mode is used on the 30 Megohm range special grounding and shielding may be required due to the absence of AC normal mode rejection 25 RESISTANCE MEASUREMENTS Cont d 2 Wire Ohms The two wire ohms mode is used most commonly when the resistance of
50. 478A is also set to the 30 Kohm WITH TYPE 44007 THERMISTOR range 4 1 2 digit display mode Autozero een 254 EE DS on and internal trigger Line 50 is the LI E E c a OUTPUT 723 F4R4H4Z1T1 same except the measurement function is Q3 9888880941 4 wire mode EE 60 80 These three lines contain the conversion ENTER 723 EB coefficients for the 44007 thermistor 94 LOGCB 90 Line 90 enters the measured resistance GE CO 72 E NRI EE ER from the 3478A H um 100 110 These two lines convert the measured END resistance to a temperature 120 The calculated temperature is displayed 130 The GOTO 90 statement returns the pro 54 gram to line 90 for another resistance measurement AG e vem gm OO E ed pa A co d a oc UG ros m LD e 198 246 EXTENDED OHMS The extended ohms feature is available only via the HP IB F7 or H7 commands With extended ohms you can measure resistances above 30 Mohms When in the Extended Ohms mode the 3478A goes to the 30 Mohm range 2wire mode An internal resistance of approximately 10 Mohms is placed in parallel with the in puts If this resistance is measured first and then the unknown resistor connected to the inputs the parallel combination can be measured and a calculation perform ed to determine the approximate value of the unknown resistance The formula for the calculation is Ri Rt Rx Ri Rt Rx is the unknown resistance Ri is the measured value of the in
51. 784 off then on again press Glen Notice that the display is being up ZERO dated more frequently indicating a E faster reading rate Also notice that l the AZ OFF annunciator is on in the display The Autozero feature is now i turned off Pressing the key sequence 2 again will turn Autozero back on Autozero is used to correct for small offsets thermal etc in the DC input amplifier circuitry of the multimeter With the Autozero feature enabled Autozero is enabled at power turn on the 3478A takes two measurements per reading a zero measurement and a measurement of the input voltage The displayed reading is the algebraic difference between the two measurements The 3478A makes the zero measurement by disconnecting the multimeter s input terminals and then shorting the internal input circuitry to circuit common It then switches back for an input voltage measurement All switching is internal and is automatic 8 AUTOZERO Cont d With autozero turned off whenever a new function or range is selected the 3478A immediately takes one final zero measurement and stores the results in its internal memory Subsequent measurements of the input voltage subtract this one zero measurement to correct the reading Since only the input voltage is measured the reading rate almost doubles AC Volts and Current AC voltage and current measurements use different input circuitry than dc voltage and current measurements Howe
52. 82 EUROPEAN AREAS NOT LISTED CONTACT SWITZERLAND Hewlett Packard S A 7 Rue du Bois du Lan CH 1217 MEYRIN 2 Switzerland Tel 022 83 81 11 Telex 27835 hpse Cable HEWPACKSA Geneve EAST EUROPEAN AREAS NOT LISTED CONTACT AUSTRIA Hewlett Packard Ges m b h Wehlistrasse 29 PO Box 7 A 1205 VIENNA Tel 222 35 16 210 Telex 135823 135066 MEDITERRANEAN AND MIDDLE EAST AREAS NOT LISTED CONTACT GREECE Hewlett Packard S A Mediterranean amp Middle East Operations 35 Kolokotroni Street Platia Kefallariou GR Kifissia ATHENS Greece Tel 808 0359 808 0429 Telex 21 6588 Cable HEWPACKSA Athens INTERNATIONAL AREAS NOT LISTED CONTACT OTHER AREAS Hewlett Packard Co Intercontinental Headquarters 3495 Deer Creek Road PALO ALTO CA 94304 Tel 415 857 1501 Telex 034 8300 Cable HEWPACK 4 20 81
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55. Crystal Display LCD gives you measurement units as part of the reading for easy to read unambiguous answers The HP IB talk listen remote and SRO status information is also available with LCD annunciators The SRQ button can be used to flag or interrupt your computer from the front panel of the 3478A Other system features of the 3478A include the Voltmeter Complete signal and External Trigger input both available on the rear panel to synchronize with scan ners or to other external devices The switchable front rear inputs let you easily connect to the 3478A for either bench or systems operation The systems package of the 3478A offers convenient rack mounting in a system Furthermore to lower your cost of ownership the 3478A is calibrated elec tronically either manually from the front panel or remotely in an automatic calibra tion system There are no internal adjustments and the calibration of all functions is done without the removal of covers The self test function verifies most of the internal circuitry of the 3478A for an indication of the proper operation of the multimeter HP IB Hewlett Packard Interface Bus is Hewlett Packard s implementation of IEEE Standard 488 1978 and ANSI MC1 1 How to Use This Manual This Operators Manual has been designed with you the operator in mind to serve as a complete reference document for using the 3478A as a solution to your measurement needs It covers both bench use and remote pro
56. E IL 60515 Tel 312 960 5760 CM CP Hewlett Packard Co 5201 Tollview Drive ROLLING MEADOWS IL 60008 Tel 312 255 9800 A CM CP E MP Indiana Hewlett Packard Co P O Box 50807 7301 No Shadeland Avenue INDIANAPOLIS IN 46250 Tel 317 842 1000 A CM CS E MS lowa Hewlett Packard Co 2415 Heinz Road IOWA CITY lA 52240 Tel 319 351 1020 CM CS E MS SALES amp SUPPORT OFFICES Arranged alphabetically by country 0 Kansas Hewlett Packard Co 1644 S Rock WICHITA KA 67207 Tel 316 265 5200 CM CS Kentucky Hewlett Packard Co 10170 Linn Station Road Suite 525 LOUISVILLE KY 40223 Tel 502 426 0100 A CM CS MS Louisiana Hewlett Packard Co P O Box 1449 3229 Williams Boulevard KENNER LA 70062 Tel 504 443 6201 A CM CS E MS Maryland Hewlett Packard Co 7121 Standard Drive HANOVER MD 21076 Tel 301 796 7700 A CM CP E MS Hewlett Packard Co 2 Choke Cherry Road ROCKVILLE MD 20850 Tel 301 948 6370 Telex 710 828 9685 A CM CP E MP Massachusetts Hewlett Packard Co 32 Hartwell Avenue LEXINGTON MA 02173 Tel 617 861 8960 A CM CP E MP Michigan Hewlett Packard Co 23855 Research Drive FARMINGTON HILLS MI 48024 Tel 313 476 6400 A CM CP E MP Hewlett Packard Co 4326 Cascade Road S E GRAND RAPIDS MI 49506 Tel 616 957 1970 CM CS MS Minnesota Hewlett Packard Co 2025 W Larpenteur Ave ST PAUL MN 55113 Tel 612 644 1100 A CM CP E MP Mississippi Hewlett
57. EL What is on the Rear Panel Figure 2 3 illustrates the rear panel of the 3478A The Rear Panel input terminals are selected by the F R switch on the instrument front panel There are two BNC connectors One is for outputting a Voltmeter complete pulse at the end of an A D conversion The second BNC connector is used to input an external trigger pulse See VOLTMETER COMPLETE and TRIGGER for more information on these connec tors And of course there is the HP IB connector The Rear Panel Switches Also on the rear panel of the 3478A is a set of 8 switches See Figure 2 3 These switches are on or in the 1 position when they are up Switch number 1 farthest to the left is the 5OHz 60Hz select switch This switch should be in the up position if a power line with 50Hz frequency is being used or down if a 60Hz power line is used This switch changes the integration period see OPTIMIZING READING RATES of the A D converter so as to obtain the greatest AC NMR and CMR rejection at the line frequency used The reading rate is slightly slower when 50Hz is selected This switch is read approximately once each minute and at power on reset Switch number 2 is not used Switch number 3 is used to select the Power on SRO PWR ON SRO feature When this feature is enabled i e the switch is up the 3478A will generate an SRQ Request Service HP IB message whenever the power is lost and then return ed such as a momentary power blackout Swi
58. M CP E MP P CHILE Jorge Calcagni y Cia Lida Arturo Burhle 065 Casilla 16475 SANTIAGO 9 Tel 220222 Telex JCALCAGNI A CM E M Olympia Chile Lta Rodrico de Araya 1045 Casilla 256 V SANTIAGO 21 Tel 25 50 44 Telex 40 565 CP COLOMBIA Instrumentaci n H A Langebaek amp Kier S A Apartado A reo 6287 BOGOTA 1 D E Carrera 7 No 48 75 BOGOTA 2 D E Tel 287 8877 Telex 44400 Cable AARIS Bogota A CMEMP COSTA RICA Cientifica Costarricense S A Avenida 2 Calle 5 San Pedro de Montes de Oca Apartado 10159 SAN JOSE Tel 24 38 20 24 08 19 Telex 2367 GALGUR Cable GALGUR CMEM CYPRUS Telerexa Ltd DO Box 4809 14C Stassinos Avenue NICOSIA Tel 45628 Telex 2894 EMP CZECHOSLOVAKIA Hewlett Packard Obchodni Zastupitelstvi v CSSR Post schranka 27 CS 118 01 PRAHA 011 Tel 66 296 Telex 121353 IHC El a DENMARK Hewlett Packard A S Datavej 52 DK 3460 BIRKEROD Tel 02 81 66 40 Telex 37409 hpas dk A CM CP E MS P Hewlett Packard A S Navervej 1 DK 8600 SILKEBORG Tel 06 82 7 1 66 Telex 37409 hpas dk CM CS E ECUADOR CYEDE Cia Ltda DO Box 6423 CCI Avenida Eloy Alfaro 1749 QUITO Tel 450 975 243 052 Telex 2548 CYEDE ED Cable CYEDE Quito A CM E P Hospitalar S A Casilla 3590 Robles 625 QUITO Tel 545 250 545 122 Cable HOSPITALAR Quito M EGYPT Samitro Sami Amin Trading Office 18 Abdel Aziz Gawish ABDINE CAIRO Tel 24 932 P intern
59. MENT CONTROL MES E SS D DEVICE ONLY ABLE TO TALK d a T 7 E e g TAPE READER h EZ oo 1 8 i 30601 602 LL ax E Figure A 2 Interface Connection and Bus Structure Eight Signal lines termed as DATA Lines are in the first set The Data Lines are used to transmit data in the form of coded messages These messages are used to program the instrument function transfer measurement data coordinate instru ment operation and to manage the system This allows you to set up the instru ment and read its measurement data Input and Output of meaasges in bit parallel byte serial form are also transferred in the Data Lines A 7 bit ASCII code normal ly represents each piece of data Data is transferred by means of an interlocking handshake technique which per mits data transfer asynchronously at the rate of the slowest active device used in that particular transfer The three DATA BYTE CONTROL lines coordinate the transfer and form the second set of lines The remaining five GENERAL INTERFACE MANAGEMENT lines are used to manage the devices on the HP IB This includes activating all connected devices at once clearing the interface and others For a detailed description of the HP IB lines commands internal operations etc refer to the HP IB Abbreviated Description Manual hp part number 5955 2903 A condensed description is also available in the Condensed Descr
60. Packard Co P O Box 5028 322 N Mart Plaza JACKSON MS 39216 Tel 601 982 9363 CM MS Missouri Hewlett Packard Co 11131 Colorado Avenue KANSAS CITY MO 64137 Tet 816 763 8000 Telex 910 771 2087 A CM CS E MS Hewlett Packard Co 1024 Executive Parkway ST LOUIS MO 63141 Tel 314 878 0200 A CM CP E MP Nebraska Hewlett Packard 7101 Mercy Road Suite 101 IBX Building OMAHA NE 68106 Tel 402 392 0948 CM MS Nevada Hewlett Packard Co Suite D 130 5030 Paradise Blvd LAS VEGAS NV 89119 Tel 702 736 6610 CM MS New Jersey Hewlett Packard Co Crystal Brook Professional Building Route 35 EATONTOWN NJ 07724 Tel 201 542 1384 A CM C E P Hewlett Packard Co W120 Century Road PARAMUS NJ 07652 Tel 201 265 5000 A CM CP E MP Hewlett Packard Co 60 New England Avenue West PISCATAWAY NJ 08854 Tel 201 981 1199 A CM CP E New Mexico Hewlett Packard Co PO Box 11634 11300 Lomas Blvd N E ALBUQUERQUE NM 87123 Tel 505 292 1330 Telex 910 989 1185 CM CP E MS New York Hewlett Packard Co 5 Computer Drive South ALBANY NY 12205 Tel 518 458 1550 Telex 710 444 4691 A CM CS E MS Hewlett Packard Co 9600 Main Street CLARENCE NY 14031 Tel 716 759 8621 Telex 710 523 1893 Hewlett Packard Co 200 Cross Keys Office FAIRPORT NY 14450 Tel 716 223 9950 Telex 510 253 0092 CM CP E MS Hewlett Packard Co No 1 Pennsylvania Plaza 55th Floor 34th Street amp 8th
61. RE MEASUREMENT WITH TYPE 44067 THERMISTOR HP 35 VERSIDH OUTPUT 723 FIR4N4Z1 OUTPUT 723 F4R4N4Z1 T OO LG G1 6012 66 ENTER 723 B 4 LOGCB P l1 7CG1 O04XCO2Z GUO4d KkQ4kQ35 5 27 2 16 1298 LISP P 26 GTO 96 140 END DVI NOU opo Corey ge gs qt E I Gi e D e ba e a iD E Operators Maintenance Chapter IV Operators maintenance information is found in Chapter IV This chapter ad dresses instaiiation procedures a com plete table of specifications what to do if you suspect problems with the 3478A and many other items of special interest to the operator Most hp service offices in the United States are NOT authorized to service and repair 3478A DMM s Notify your local hp sales office for specific infor mation on where to send the instru ment for repair DEVICE A ABLE TO TALK LISTEN AND CONTROL 6 9 CALCULATOR Remote Programming Chapter IH If your needs are in the area of remote programming the 34784 then Chapter Hi is where you need to look for pro gramming information Numerous ex amples are given to enhance the pro gramming discussion At the end of this Chapter are several application program examples designed to solve frequently encountered measurement problems Remember that you will want to read Chapter II prior to begin ning Chapter Ill 3478R VERIFICATION PROGRAM REMOVE ALL INSTRUMENTS FROM THE BUS EXCEPT
62. Resolution Range 5 Digi 5X Digit 4 Digit 3 Digit 4 T peu uk rm 300mA 303 099mA 1uA 104A 100yA 3 A 3 08099 A 104A 100A 1mA Maximum Input non destructive 3A from 250V source fuse protected Measurement Accuracy 96 of reading number of counts Auto zero ON 5 digit display accuracy specified for sine wave inputs only gt 1096 of full scale 1 YEAR CAL TEMP 5 C Auto zero Off 5 digits for a stable environment x 1 C for 24 hrs add 10 counts to accuracy specification Temperature Coefficient 0 C to Cal Temp 5 C Cal Temp 5 C to 55 C 5 digits auto zero ON 0 02196 of reading 10 counts C Maximum Burden at Full Scale 1V Crest Factor 24 1 at fuii scaie Maximum Reading Rates Same as ac volts GENERAL INFORMATION Frequency 3A 20Hz 50Hz 1 54 4 163 2 24 4 163 50Hz 100Hz 81 163 1 5 163 100Hz 1kHz 81 163 1 5 163 1kHz 10kHz 72 163 1 42 163 10kHz 20kHz 86 163 1 56 163 Operating Temperature 0 to 55 C Humidity Range 95 R H O to 40 C Storage Temperature 40 C to 75 C Warm up Time 1 hr to meet all specifications integration Time Line Frequency Number of Digits 50Hz 60Hz t i 5 i 200ms 166 7ms 4 20ms 16 67ms 3 2ms 1 667ms 82 Power AC Line 48 440Hz 86 250V see configuration Maximum Power lt 12 watts
63. S S R Hewlett Packard Co Representative Office Pokrovsky Blvd 4 17 KV12 MOSCOW 101000 Tel 294 2024 Telex 7825 HEWPACK SU VENEZUELA Hewlett Packard de Venezuela C A Apartado 50933 3A Transversal Los Ruices Norte Edificio Segre 2Y3 CARACAS 1071 Tel 239 4133 239 4777 239 4244 Telex 25146 HEWPACK Cable HEWPACK Caracas A CP E MS P YUGOSLAVIA Iskra Commerce Representation of Hewlett Packard Sava Centar Delegacija 30 Milentja Popovica 9 11170 BEOGRAD Tel 638 762 Telex 12042 12322 YU SAV CEN Iskra Commerce Representation of Hewlett Packard Koprska 46 61000 LJUBLJANA Tel 321674 315879 Telex ZAMBIA R J Tilbury Zambia Ltd P O Box 2792 LUSAKA Tel 81243 AEMP ZIMBABWE Field Technical Sales 45 Kelvin Road North P B 3458 SALISBURY Tel CEMP FOR COUNTRIES AND AREAS NOT LISTED CANADA Ontario Hewlett Packard Canada Ltd 6877 Goreway Drive MISSISAUGA Ontario L4V 1M8 Tel 416 678 9430 Telex 610 492 4246 EASTERN USA Maryland Hewlett Packard Co 4 Choke Cherry Road Rockville MD 20850 Tel 301 258 2000 MIDWESTERN USA Illinois Hewlett Packard Co 5201 Tollview Drive ROLLING MEADOWS IL 60008 Tel 312 255 9800 SOUTHERN USA Georgia Hewlett Packard Co PO Box 105005 450 Interstate N Parkway ATLANTA GA 30339 Tel 404 955 1500 WESTERN USA California Hewlett Packard Co 3939 Lankersim Blvd LOS ANGELES CA 91604 Tel 213 877 12
64. TU SS 44 Measuring Current 11 REMOTE shh ee ise REGES Gd 45 DISPLAY anida 12 Examples oo 45 i How itis Used oooo 12 C nmmenhts cs vcl d VETERES 45 Normal Se ic 12 REQUIRE SERVICE SRQ 46 Message 13 How touseSROQ 46 f User Generated Message 15 Status Register and Status Byte 47 Changing the Number of Digits Setting the SRO Mask 47 Displayed 15 SPOLE e renge ele aa eek 50 AmnunciatorS 17 EXaAMpl a sun aod a are aa A 50 OPTIMIZING READING RATES 18 Comments oo ad Sin 50 Why Optimize 18 TRIGGER ooooooooo ooo 53 Your Signal Environment 18 Examples e hie et ees 53 Integration Times 18 Comments 53 Autozero 2 ee 19 Topics in Advanced Programming 54 Other Factors Influencing the TEMPERATURE MEASUREMENTS 54 Reading Rate 19 EXTENDED OHMS sss 55 RANGING oia iaa CE 20 dBm MEASUREMENTS 56 What About Ranging 20 MAXIMUM READING RATE 57 Reading the Display 20 STATUS BYTE COMMAND 58 Autorange llle lees 21 3478A Programming Commands 59 N Manual Ranging 22 REAR PANEL oo o oooo 23 Chapter Page What is on the Rear Panel 23 iV OPERATORS MAINTENANCE 63 The Rear Panel Sw
65. These accessories are of fered to help you maximize the usability and convenience of your 3478A Table 4 1 Accessories Accessory Number Description 10023A Temperature Probe 10631A HP IB Cable 1 Meter 39 37 inches 10631B HP IB Cable 2 Meters 78 74 inches 10631C HP IB Cable 4 Meters 157 48 inches 10631D HP IB Cable O 5 Meters 19 69 inches 11000A Test Leads Dual banana both ends 11002A Test Leads Dual banana to dual alligator 11003A Test Leads Dual banana to probe and alligator 11096B RF Probe 34111A High Voltage Probe 34118A Test Leads banana to probes with safety guard rings Option 907 Front Handle Kit 5061 1088 Option 908 Rack Mounting Kit 5061 0072 Option 910 Additional Operators Manual and Service Manual hp Part Number 03478 90000 03478 90001 63 Initial Inspection Your 3478A was carefully inspected before it left the factory It should be free of mars or scratches and in proper working order upon receipt You should however inspect the instrument for any damage that may have occurred in transit If the shipping container or cushioning material is damaged it should be kept until the contents of the shipment have been checked for completeness and the instrument has been mechanically and electrically inspected Procedures for checking the elec trical performance of the 3478A are given in the 3478A SERVICE MANUAL hp part number 03478 90001 If there is any mechanical d
66. am FIHO w DISF Ba PRIHT 4 VERIFICATION ABORT FAIL ED xr ja D I P Bae FEINT CHECK FOR PROFER HP 1 Lines 520 570 E HDDEESS Check Bits In Error Bere PRIHT AHO RUM THE PROGRAM A Register And Display Ap GAINE propriate Message STOP SELF TEST SE PASS Op OISE EE SELF TES RE D D en CO m LO Lines 590 620 714p SELF TEST Failed 216 RETURN Verification Aborted sm 3478 4F 77 Verification Program and Flow Chart Cont d SUGROUTIHE FOR FROGRAM Coo ES zB DISP TESTING FROHT PANEL SR p GUTPUT Di E OH TIMERS 2 50 OH IHMTRE D gG TU EHRHELE CNTR D DISP i DISP mg PSA FRONT FHHEL E z OUTPUT Di FIRRH H HENT H E 3 OUTPUT Di Di OUTPUT Di GQeO1SPLAyY TES Ko ken ko m po pt Ka ti DzDISPLHY TEST EEF WAIT Sage A ME WAIT Sana FAS DISPLAY T BEEF GE rose 5 m rt cum DA FCE i Bl E EH sip Mick Ponte ws zT IF EIT EZ2 45 THEH 334 E a PRINT FRONT PHHEL Seo HOT F GR Hc TO 8 STEP i CEMOWLEOGED E TED 350 DISP w DISP ae VERIFICATION menn EL HEDETED i STOP E ASSES S90 DISP 3 FRONT PANEL SR PAS e euan S ES R MESET SR SED t E GOTO oe e i T 1PANST S06 SRO KEY NOT PRESSED oe a ee ee 210 PRINT SRE KEY HOT PEEZSED IF zu Das ANO Z lt 0AF THEN 1444 4 TED H 14258 PRINT ZERO ERROR OH THE 29 520 PRINT EEE VERIFICATION ABGR 228 STOP Ar EANGET Se ir 476 q HER n M HD n 348 DISP amp DISP amp DISP
67. amage or the contents are incomplete or the instrument does not pass its performance tests notify the nearest Hewlett Packard office a list of the hp Sales and Service Offices is located in the back of this manual If the shipping container is damaged or the cushioning material shows signs of stress notify the carrier as well as the Hewlett Packard office Save the shipping materials for the carrier Preparation for Use Power Requirements The 3478A Digital Multimeter requires a power source of 100 120 220 or 240 Vac 10 5 48 Hz to 440 Hz single phase Maximum power consump tion is 25 VA Line Voltage Selection Refer to the rear panel of the 3478A for the line voltage option label Make cer tain that the option marked on the label is the same as the nominal line voltage for your area Also check the left most switch 50 60Hz switch for the proper set ting Le up for 50Hz and down for 60Hz Table 4 2 lists the available power op tions Table 4 2 Line Voltage Options Frequency Line Voltage Option No 315 100 50 250 mA hp part number 2110 0004 316 100 60 250 mA 325 120 50 250 mA 326 120 60 250 mA 335 220 50 125 mA hp part number 2110 0318 336 220 60 125 mA 345 240 50 125 mA 125 mA slo blo fuse 64 CAUTION Before connecting the multimeter to an ac power source verify that the ac power source matches the power re quirements of th
68. ambient temperature range of 23 C 5 C 73 F 9 F The instrument may be operated within an ambient temperature range of O C to 55 C 32 F to 131 F but with reduced ac curacy WARNING To prevent potential electrical or fire hazard do not expose the multimeter to rain or moisture Specifications The specifications for the 3478A are the performance characteristics of the instru ment which are certified These specifications are listed in Table 4 3 and are the performance standards or limits against which the multimeter is tested Included in the table are some supplemental characteristics of the 3478A and should be con sidered as additional and general information for you the user Because of the many operational capabilities of the 3478A exercise care when checking the in struments specifications Any changes in the specifications due to manufacturing changes design or traceability to the National Bureau of Standards will be covered in a manual change supplement Interface Connections The hp 3478A is compatible with the Hewlett Packard Interface Bus HP IB HP IB is Hewlett Packard s implementation of IEEE Std 488 1978 Standard Digital Interface for Programmable Instrumentation Refer to Appendix A for specific in formation regarding HP IB 67 The 3478A s HP IB connection is made by an HP IB Interface cable to the 24 pin HP IB connector located on the rear panel A typical interconnection of HP IB is sh
69. an answer or be retriggered The pulse is a negative going TTL compatible pulse of about 14S duration Using the Voltmeter Complete Pulse The following illustration shows one way to use the the Voltmeter Complete and External Increment feature of the 3478A in conjunction with the hp Model 3497A Data Acquisition Control Unit Once the connections are made the 3497A advances to the next channel with each Voltmeter Complete pulse PCS Figure 2 6 Using Voltmeter Complete 34 Chapter lll Remote Programming Introduction In this chapter you will learn about remote programming your 34784 over the Hewlett Packard Interface Bus HP IB using a computer controller If you are not familiar with HP IB or some of the terms used in this chapter Appendix A contains a concise description of HP IB Be sure that you have read through or at least familiarized yourself with Chapter 2 of this manual before starting this chapter You will need to understand the operating characteristics of the 3478A before you begin programming it Scope The descriptions presented in this chapter are in general terms to optimize the flow of information regardless of the type of controller you are using This means that both the inexperienced user as well as the experienced programmer will be programming the 3478A efficiently and productively with minimum instruction time There are however many example programs given to enhance the discus sion most of
70. ania Hewlett Packard Co 1021 8th Avenue King of Prussia Industrial Park KING OF PRUSSIA PA 19406 Tel 215 265 7000 Telex 510 660 2670 A CM CP E MP Hewlett Packard Co 111 Zeta Drive PITTSBURGH PA 15238 Tel 412 782 0400 A CM CP E MP South Carolina Hewlett Packard Co PO Box 6442 6941 0 N Trenholm Road COLUMBIA SC 29260 Tel 803 782 6493 CM CS E MS a D SALES amp SUPPORT OFFICES Arranged alphabetically by country UNITED STATES Cont South Carolina Cont Hewlett Packard Co 814 Wade Hampton Blvd Suite 10 GREENVILLE SC 29609 Tel 803 232 0917 C Tennessee Hewlett Packard Co P O Box 22490 224 Peters Road Suite 102 KNOXVILLE TN 37922 Tel 615 691 2371 A CM MS Hewlett Packard Co 3070 Directors Row MEMPHIS TN 38131 Tel 901 346 8370 A CM CS MS Hewlett Packard Co Suite 103 478 Craighead Street NASHVILLE TN 37204 Tel 615 383 9136 CM MS Texas Hewlett Packard Co Suite 310W 7800 Shoalcreek Blvd AUSTIN TX 78757 Tel 512 459 3143 CM E Hewlett Packard Co Suite C 110 4171 North Mesa EL PASO TX 79902 Tel 915 533 3555 CM CS E MS Hewlett Packard Co 5020 Mark IV Parkway FORT WORTH TX 76106 Tel 817 625 6361 CM C Hewlett Packard Co P O Box 42816 10535 Harwin Street HOUSTON TX 77036 Tel 713 776 6400 A CM CP E MP Hewlett Packard Co 3309 67th Street Suite 24 LUBBOCK TX 79413 Tel 806 799 4472 M Hewlett Packard Co P O
71. anually set the 50 60 Hz line switch to the 60Hz position This switch is on the rear panel of the 3478A Second the program sets the 3478A to the autorange mode If you know the approximate value of the voltage to be measured you can change the RA command in line 50 to reflect an appropriate range The program accepts 100 readings from the 34784 and stores them into a buffer B When all the readings have been taken the readings are printed With the hp 85 computer the 100 readings are accepted in approximately 1 4 seconds lines 30 40 50 MAAIMUM READING RATE he 85 VERSION DIM B L13021 IOBUFFER B 60 OUTPUT 723 FIRRHNZZ28D3 TRANSFER 723 TO B FHS COU HT 1300 FOR I 1 TO 1266 STEP 13 J I 168 FRIHT B LI 1 HEST I 90 100 57 Description B is setup as an I O Buffer to store 1300 bytes of data The 3478A outputs 13 bytes per reading in the form d ddd ddE d Cr LF Therefore for 100 readings the buffer must be dimensioned to 1300 The eight extra bytes are for overhead in the hp 85 Line 50 programs the 3478 to dc volts autorange on 3 1 2 digit display mode autozero off display off You may want to replace RA to reflect an appropriate range The TRANSFER statement is the fastest possible means to transfer data from the 3478A address 723 to the I O buffer B FHS is Fast Handshake COUNT 1300 means that only 1300 bytes will be ac cepted These two lines set up two variabl
72. applied voltage C A gain calibration is attempted which is outside the range available approximately t 796 of full scale An AC voltage calibration is attempted and the applied voltage is not 3VAC e A calibration is attempted via the bus with the C command and a valid target number was not found in the display ACI VALUE ERR At the end of an AC voltage calibration when the 3478A attempted to compute the calibration constant for AC current it computed a number outside of the allowed range This could be caused by an invalid calibration constant on either the 300mV DC range or the 3A DC range The ac voltage calibration is valid however GENERAL USAGE MESSAGE HPIB ADRSxx This is the HP IB address of the 3478A xx indicates the actual address of the the in strument decimal and may be altered by the address switches on the rear panel OVLD This stands for overload and indicates that the input is too great for that particular range 14 DISPLAY Cont d User Generated Message Under computer control the 3478A can display your own user messages of up to 12 characters Refer to Section Ill Remote Programming for more information on this DESIGNED FOR GIS Commands SYSTEMS D2text Places the message text into the display D3text Places text into display but the display is not updated D1 Returns the 3478A to NORMAL display Changing the Number of Digits Displayed When you are displaying measurement results
73. ational Engineering Associates 24 Hussein Hegazi Street Kasr el A ni CAIRO Tel 23 829 Telex 93830 EM Informatic For Computer Systems 22 Talaat Harb Street CAIRO Tel 759006 Telex 93938 FRANK UN C EL SALVADOR IPESA Boulevard de los Heroes Edificio Sarah 1148 SAN SALVADOR Tel 252787 A C CM E P FINLAND Hewlett Packard Oy Revontulentie 7 SF 02100 ESPOO 10 Tel 90 455 0211 Telex 121563 hewpa sf A CM CP E MS P FRANCE Hewlett Packard France Le Ligoures Bureau de Vente de Aix en Provence Place Rom e de Villeneuve F 13090 AIX EN PROVENCE Tel 42 59 41 02 Telex 410770F A CM CS E MS P E a SALES amp SUPPORT OFFICES Arranged aiphabetically by country PORTUGAL Telectra Empresa T cnica de Equipmentos El ctricos S a r 1 Rua Roarigo da Fonseca 103 PO Box 2531 P LISBON 1 Tei 19 68 60 72 Telex 12598 ACEP Mundinter Intercambio Mundial de Com rcio Sard DO Box 2761 Avenida Antonio Augusto de Aguiar 138 P LISBON Tel 19 53 21 31 53 21 37 Telex 16691 munter p M PUERTO RICO Hewlett Packard Puerto Rico P O Box 4407 CAROLINA Puerto Rico 00630 Calle 272 Edificio 203 Urb Country Club RIO PIEDRAS Puerto Rico 00924 Tel 809 762 7255 Telex 345 0514 ACP QATAR Nasser Trading amp Contracting DO Box 1563 DOHA Tel 22170 Telex 4439 NASSER M Scitecharabia DO Box 2750 DOHA Tel 329515 Telex 4806 CMPARB P ROMANIA Hewlett Packard Rep
74. cating the service or repair needed Include the model number and full serial number of the instrument In any correspondence identify the instrument by model number and full serial number 74 Further Considerations Cleaning Disconnect the 3478A from its ac power source before cleaning The multimeter can be cleaned with a soft cloth dampened either in clean water or in water con taining a mild detergent Do not use an excessively wet cloth or allow water in side the instrument Do not use any abrasive cleaners especially on the display Do not press too hard on the display The panel area surrounding the input ter minals should not be touched because oils on the surface caused by finger prints may cause leakage paths and decrease the input impedance To maintain the high input impedance of the multimeter the input terminal area should be cleaned periodically with a cotton swab dipped in isopropyl alcohol 75 K LA LA T xx ER CH am CH LA af y rm 2 ven rafe Qo cc EA pae re LA 1 LO Gei va p AES LA Ka Ka EN k Bic far Ka LA me La XN pra Le m XX rA n be mu t Le LA mer 74 CH GI LA pa ka LA Fa CO CO e LA m DE am n atm am EX LA po h P2 p3 qp es Le 3 zn Dex T LA A GI cpm i SS Ka 1 WES IA OUO er A ve es Al LA LN eae LA T E Gl GIG GI o1 Po PO Po P
75. command is the last one received and will be in effect Instructions are sent to the 34784 as a series of 7 bit ASCII characters parity bit is ignored All lowercase letters spaces commas and semicolons are ignored and may be freely used to format commands for easy readability All null characters carriage return line feed form feed and vertical and horizontal tab characters are also ignored All other characters and sequences not explicitly allowed see the Command Table will result in an error Errors will be discussed later For example sending the message OUTPUT 723 Function 1 Range 1 would be the same as OUTPUT 723 F1R1 When a multicharacter command is received if a character is received which does not fit into the syntax of the command the command will be aborted and an error will be generated An attempt is made to process the character as if it were the first character of another command For example the command FR3 will cause a syntax error but then go on to range 3 that is R3 See Require Service Status Register Commands which accept binary arguments represented by x in the command table and the D2 and D3 commands are exceptions to the above rules Any of the 256 possible 8 bit bytes may be sent as a binary argument any ASCII character greater than 31 decimal may be sent as part of a text message see Appendix B Note however that lowercase alpha characters are not represented as alpha characters in
76. cted manual range display turned off see HP IB command D3 a positive voltage measured and internal trigger selected 19 RANGING What About Ranging The task of selecting the proper range on the 3478A may be done either automatically by the multimeter or manually with the front panel keys Reading the Display SC Do This Short the 3478A s input terminals press Notice that the M RNG annunciator AUTO turns on in the display This indicates MAN that the meter is in the manual range mode Pressing this key again returns the meter to the autorange mode press Press each of these keys several times Watch the decimal point as it OR moves across the display Also notice the range annunciator in the display For example if the meter is in the DC Volts function the display should in dicate MVDC or VDC depending upon the range selected Try this in the other measurement modes The display is always read directly and gives an indication of the range as a com bination of decimal point and function display Try connecting a variable dc power supply to the multimeter Make sure that the meter is in the DC volts function and autorange mode As you adjust the power supply watch the display The display will momentarily go blank as the meter changes ranges You might see a reading such as 47 215 MVDC Reading the display directly this would indicate a measurement of 47 215 milli volts dc 047215
77. cteristics Auto Zero Off Maximum 5 digit for a stable environment 1 C for lt 24 hrs add Reading Resolution 110 counts to accuracy specification for 30mV range 11 Range H 5 Digit 5 Digit 4 Digit 3 Digit counts for 300mV and 30V ranges 3 counts for 3V and 300V range 30mv 30 3099mV 100nV pV 104V 8 300mV 303 099mV 14V 104V 1004V Temperature Coefficient 3 X4 boa E ET 0 C to Cal Temp 5 C Cal Temp 5 C to 55 C 30 V 30 3099 V 100u4V 1mV 10mV 5 digit display auto zero ON 300 V 303 099 V 1mV 10mV 100mv 4 of reading number of counts C Input Resistance 30mV 300mV 3V ranges gt 1 o1 Range Temperature Coefficient 30V 300V ranges 10M9 1 30mV 0 0028 5 300mV 0 0005 0 5 Maximum Input Voltage non destructive 3 V 0 0004 0 05 30 V 0 0006 0 5 Hi to Lo 303V rms or 450V peak 300 V 0 0004 0 05 Hi or Lo to Earth Ground 500V peak Noise Rejection Measurement Accuracy In dB with 1kQ imbalance in Lo lead AC rejection for 50 of reading number of counts 60Hz 0 1 Auto zero ON Auto zero ON AC AC oc 5 Digit Mode Display NMR ECMR CMR Cal Temp 1 C Cal Temp 5 C 5 digits 80 140 140 Range 24 Hours 90 Day 1 Year 4 digits 59 120 140 3 digits O 60 140 30mV 0 030 41 0 040 41 0 044 41 300mV 0 007 5 0 020 5 0019 5 Maximum Reading Rates readings sec 3 V 0 006 2 0 019 2 0 019 2 MRP Tm S 30 v 0 0
78. d takes about 30mS to complete after which the considerable overhead of updating the display is bypassed means a faster reading rate This enables the 3478A to respond to commands more rapidly in certain conditions If the display is not updated for about ten minutes it will blank out completely The display can be restored by pressing the LOCAL key or by executing a D1 D2 or D3 com mand Home command This command places the 3478A into the DC Volts function Auto Range Single Trigger state 4 1 2 digit display with Auto Zero on Any result ready to be output to the bus or display is erased The external trigger input is disabled This command is equivalent to F1TAR 2RAZ1N4 Measure DC Volts This command causes one DC Voltage measurement to be made following which an enter command from the controller will access the result This command is like the HO command except that a trigger occurs This command is equivalent to FIR 2RAZ1NAT3 Measure AC Volts identical to H1 except for the function Measure 2 wire Ohms Identical to H1 except for the function Measure 4 wire Ohms identical to H1 except for the function Measure DC Current Identical to H1 except for the function Measure AC Current Identical to H1 except for the function Measure Extended Ohms Identical to H1 except for the function 60 3478A Programming Commands Cont d panne NN Binary Status If the 3478A is addressed to talk afte
79. display will turn on and the HP IB SRQ message will be sent The controller must be programmed to respond to the SRQ message The Status Byte is an 8 bit byte that may be used to determine the current status of the 3478A regardless of whether an interrupt SRQ has occurred The Status Byte comes from the status register and is output in response to a serial poll which is described in the next section Bit 7 Bit 3 Bit 2 Bit 1 power on Hardware Syntax N A Reset Failed Error Error always O Figure 3 3 Status Register Setting the SRQ Mask The SRQ mask can only be set to mask bits O 5 on the Status Register Default mask value is OO To set the mask first determine which conditions you want to interrupt the controller e g data ready calibration procedure failed syntax error etc Determine the two digit octal code for those conditions Then output the M instruction mnemonic followed by the octal code as the qualifier that is Masi where xx is the octal code Think of the SRQ mask as a mask that sits over the lower six bits of the status register and masks out those conditions you don t want to cause an interrupt Figure 3 4 shows the status register and the SRQ mask set for bit O Data Ready 01 octal For Data SSN SRO _ 0 Mask Status Register Figure 3 4 Status Byte and SRQ Mask 47 Example 1 Data Ready SRO Data Ready is a feature of the 3478A that allows it to interrupt the controlle
80. dress Sent on Data Lines Output DATA from 3478A 89 Bus fy Clear Message To send the CLEAR Message Bus Management Lines ATN IFC SRQ REN EOI T E X X X Sent on Data Lines octOO4 Clear Command To send the CLEAR MESSAGE Only to the 3478A Bus Management Lines ATN IFC SRQ REN EOI F F X T X Sent on Data Lines 6 oct 004 Universal Unlisten Clear Command 3478A Listen Address Status Byte Message To Serial POLL the 3478A obtain Status Byte Bus Management Lines ATN IFC SRQ REN EOI T F X X F Sent on Data Lines 6 oct030 W 5 Controller Listen Address 3478A Talk Address Universal Unlisten 3478A Listen Address Serial Poll Enable then Bus Management Lines ATN IFC SRO REN EOI F F X x F Sent on Data Lines 3478A Status Byte f SRO was true it will switch to the false state and finally Bus Management Lines ATN IFC SRQ REN EOI T F F X F Sent on Data Lines oct 031 Serial Poll Disable 90 Require Service Message To send REQUIRE SERVICE MESSAGE Bus Management Lines ATN IFC SRQ REN EO X X T X X Local Lockout Message To enable LOCAL LOCKOUT Bus Management Lines ATN IFC SRQ REN EOI T FE X T F Sent on Data Lines oct 021 Local Lockout instruction to maintain LOCAL LOCKOUT Bus Management Lines ATN IFC SRQ REN EOI X X X T X Clear Lockout Set Local Message To CLEAR LOCAL LOCKOUT and set LOCAL Bus Management Lines ATN IFC SRQ REN
81. e instrument to which the Instruction Message is being directed i e 723 It also includes any delimiters required by the computer language syntax A delimiter is a character that is used either to separate one ex pression from another or to terminate a list Delimiters include semicolons quota tion marks commas spaces etc When linking instructions it is not necessary to add delimiters between instructions Note 2 Some computers and controllers generate a Carriage Return Line Feed CR LF automatically as part of the output command Check the output command syntax for your specific computer The CR LF is a delimiter that terminates a list The 3478A ignores the CR LF except in the D2 or D3 commands Figure 3 1 Sending Instructions 37 Procedure Decide what you want the instrument to do and determine the appropriate Opera tion Mnemonic s For example the Operation Mnemonic for function codes is F the Mnemonic for range codes is R etc Specify the Qualifier and Data as necessary Let s look at an example and break down the instruction message To set the 3478A to the DC Volts function and 30 volt range the following message would be sent interface 3478A select code address 2 instruction messages linked together OUTPUT 723 F1 R1 E sets range to 30 volt range sets function to DC volts F is mnemonic and 1 is qualifier computer output command syntax depends on the computer being used See Note 1
82. e multimeter as marked on the option label on the rear panel of the instrument Only qualified service trained personnel are allowed to reconfigure the 3478A for the different line voltage options Power Cords and Receptacles Figure 4 1 illustrates the different power cord configurations that are available to provide ac power to the 3478A The hp part number shown directly below the in dividual power plug drawing is the part number for the power cord set equipped with the appropriate mating plug for that receptacle If the appropriate power cord is not included with the instrument notify the nearest hp Sales and Service of fice 250 V 250 V 250 V 250 V OPERATION OPERATION OPERATION OPERATION XV E qo Ko PLUG SEV 1011 1959 24507 PLUG CEE7 V11 PLUG CEE22 Vi PLUG DHCR 107 TYPE 12 CABLE HP 8120 1692 CABLE HP 8120 1860 CABLE HP 8120 2956 CABLE HP 8120 2104 125V 6A 250 V 250 V 250 V 6A 125 V 6A OPERATION OPERATION IN DW i xr K ES A SE Te A y Ss u y E PLUG NEMA 1 15P PLUG NZSS 198 AS C112 PLUG BS 1363A PLUG NEMA G 15P PLUG NEMA 5 15P CABLE HP 8120 0684 CABLE HP 8120 0696 CABLE HP 8120 1703 CABLE HP 8120 0698 CABLE HP 8120 1521 S D 8 4195 Rev The number shown for the plug is the industry identifier for the plug only The number shown for the cable is an HP part number for a complete cable including the plug UL listed for use in the United States of America Fig
83. e remaining seven bits indicate optional conditions defined by the device This byte is sent from the talking device in response to a Serial Poll operation performed by the controller j Status Bit A byte that represents the operational conditions of a group of devices on the HP IB Each device responds on a particular bit of the byte thus identifying a device dependent condition This bit is typically sent by devices in response to a parallel poll operation k Pass Control The bus management responsibility is transferred from the ac tive controller to another controller by this message l Abort The system controller sends this message to unconditionally assume control of the HP IB from the active controller The message will terminate all bus communication but does not implement the CLEAR message The 3478A interfaces to the HP IB as defined by the IEEE Standard 488 1978 The interface functional subset which the 3478A implements is specified in Table A 1 Table A 1 3478A Device Capability SH1 Source Handshake complete capability AH1 Acceptor Handshake complete capability T5 Basic talker with serial poll talk only mode and unaddress with MLA TEO No extended talker L4 Basic listener unaddress when MTA LEO No extended listener SR1 Service request complete capability RL1 Remote Local complete capability PPO No parallel poll capability DC1 Device Clear complete capability DT1 Device Trigger complete capabili
84. eed to read fast so that you don t waste valuable computer time waiting for a measurement result Whatever your reason for optimizing reading rates the 3478A can solve many of these application problems Your maximum reading rate with the 3478A is in fluenced by several factors These include the signal environment line related and broadband noise thermals etc the desired accuracy and convenience features such as autorange or autozero The speed and timing of the A D process is depen dent upon a number of factors The number of digits of resolution selected whether or not the autozero feature is enabled and the selected function deter mine how long it takes for the A D to make a conversion The reading speed is also affected by the value of the measured voltage or current or resistance and whether the display is turned on or off HP IB D3 command turns the display off see Chapter 3 Your Signal Environment The signal that you are trying to measure is subject to line related and broadband noise which can interfere with your measurement The 3478A works to reduce or reject this kind of noise by using a form of Analog to Digital A D conversion call ed integration Integration is a process where the effect of line related noise is averaged to zero over the period of an integral number of power line cycles PLC s during an A D conversion The measure of the ability of the multimeter to measure dc voltages in the presence of ac volta
85. erminals If this resistance is measured first and then your unknown resistor connected to the in put terminals the parallel combination can be measured and a calculation perform ed to determine the approximate value of the unknown resistance The formula for the calculation is Ri Rt Rx ATA 26 RESISTANCE MEASUREMENTS Cont d Rx is the unknown resistance Ri is the measured value of the internal 10 Mohm resistor and Rt is the measured value of the parallel combination The test leads used should be very short preferably a shielded twisted pair to minimize noise pick up A program to make the necessary measurements perform the calculations and display the value of the unknown resistor is given in Chapter Ill DESIGNED FOR 110 Command SYSTEMS F7 Selects the Extended Ohms function also H7 2 wire mode LEAD RESISTANCE 1 02 INPUT 2 WIRE f SENSE 4 WIRE 28140 TYPE 4404 THERMISTOR AT 20 C 3A MAX ALL TERM 1 02 500Vpk A MAX MEASURED RESISTANCE L IS 2816 04 AN ERROR 3A 250V OF 07 FUSE Internal to the 3478A 2 WIRE OHMS MEASUREMENT Figure 2 4 Resistance 27 LEAD RESISTANCE N SENSE INPUT 4 WIRE 2814 ALL TERM 500Vpk MAX 3A 250V FUSE 4 WIRE OHMS MEASUREMENT Measurements e Eer Other t Oonsiderations 1 Always use the shortest possible test leads especially at the
86. es and J to pull out individual measurements from B is incremented in steps of 13 because the 3478A sends 13 characters per reading We are only concerned with the first 11 characters though CR LF is ig nored Therefore J is specified as 10 characters beyond I Line 90 prints an individual substring of B specified by and J Line 100 refers back to line 7O and in crements for the next reading OB um ra em emu im On e 78 118 Om D uim GD STATUS BYTE COMMAND There are 5 bytes each 8 bit wide which may be used to determine the current state of the 3478A If the multimeter is addressed to talk after reception of the B command it will output the 5 bytes The meaning of the individual bytes is given in the table of 3478A programming commands The first of the following two programs demonstrates how to get the binary representation of the 5 bytes The second program shows how the first three bits of the first byte may be used to indicate the measurement function the 34784 is set to Similar steps may be used on the remaining bits and the other 4 bytes BIHARY STATUS EXAMPLE t hr 85 VERSI N 3472A ADDRESS OUTPUT 723 B ENTER 723 USING EZ BS B4 B5 DISP BYTE 1 BITCB1 73 B1T CBi 6 gt 9 BITCB1 59 BITCB1 43 46 IT B1 329 BIT B1 2 BITCB1 12 BIT amp B1 85 DISP BYTE 2 BIT amp 4Bz 725 BIT CEZ2 65 BITCBZ 5 BITCBZ 4D5 B ITCBZ 32 BITCB2 25 BITCB2 1 BITKB2 8 DISP BYTE
87. esponds to the HP IB CLEAR command and per forms its internal self test Test 2 PROGRAM CODES The test starts by verifying that the 3478A can send an SRO and that the com puter will respond to it Next an illegal code is sent to the 3478A to be certain that it rejects it Then all possible combinations of autozero function and range codes are sent to the 3478A In addition all display modes trigger modes and the preset commands are tested Finally two readings are taken One from the the 300V dc range that is checked to be sure there are no offsets The second reading checks for an overload condition from the 2 wire ohms mode 72 Warranty Information Certification Hewlett Packard Company certifies that this product met its published specifica tions at the time of shipment from the factory Hewlett Packard further certifies that its calibration measurements are traceable to the United States National Bureau of Standards to the extent allowed by the Bureau s calibration facility and to the calibration facilities of other International Standards Organization members Warranty This Hewlett Packard product is warranted against defects in material and workmanship for a period of one year from date of shipment During the warranty period Hewlett Packard Company will at its option either repair or replace pro ducts which prove to be defective For warranty service or repair this product must be returned to a service facility
88. ger Fast Trigger works the same as T3 except that in AC Volts AC Current or the two highest ohms range the initial settling delay is omitted If more than one reading is necessary because of auto ranging or if the DMM must change ranges or functions to perform the measurement the delay will occur nor mally 59 3478A Programming Commands Cont d Explanation Autozero off Autozero on Type Command Autozero Write To Display D1 D2text D3text Preset Commands Return from D2 or D3 to NORMAL DISPLAY The D2 command places the message text into the 3478A display The message can contain any of the 64 ASCII characters from decimal 32 through 95 inclusive The message may be as long as necessary to fill up the 12 characters in the display Note that the period comma and semicolon go bet ween characters This command is terminated by any control character such as a CR If more than 12 characters are sent the extra characters are ignored un til a control character is received If the terminating control character is anything but an HT LF VT FF or CR it will result in a syntax error This command also locks the display until an error occurs a D1 command is received a device clear is received or a front panel key is pressed Like the D2 command above this places the message text into the display It also turns off all dedicated annunciators and then stops updating the display This comman
89. ges at power line frequencies is called Normal Mode Rejection NMR The NMR of the 3478A is largely dependent upon the number of digits displayed An important part of this process is to make certain that the 50 60 Hz line switch S1 on the rear panel is set properly up for 5OHz line frequency and down for 60 Hz Integration Times Changing the number of digits of display does more than change the resolution of the reading It actually changes the INTEGRATION TIME which determines the reading rate The integration time is not the same as the time for one measure ment the integration time is the time period in PLC s during which the voltmeter samples the input voltage At 4 1 2 digits of display the time required for one in tegration period is one PLC 16 2 3 mS at 60Hz line frequency or 20mS at 50Hz 18 At 3 1 2 digits of display the integration time is 1 PLC Normal Mode Rejection NMR is a measure of the ability of the voltmeter to accurately measure dc voltages in the presence of ac voltages at power line frequencies The 3478A has much better NMR at the 4 1 2 digits of display 60 db than at 3 1 2 digits Odb because of the integration times At 5 1 2 digits of display the 3478A takes ten 10 readings from the 4 1 2 digit mode and averages them together This pro vides the greatest amount of noise rejection 80db Autozero The thermal stability of the measurement environment is also a very important consideration By
90. gramming Maintenance procedures such as installation were intentionally placed later in the manual Chapter 4 because this information is seldom referred to If however you have just received your 3478A you may want to read that information A separate service manual for the 3478A contains the information on calibration performance testing and service Familiarize yourself with the 3478A by looking through this manual The best way to feel at ease with the instrument is to sit down with this manual and the 3478A and key in the examples shown It won t take long to become familiar with the in strument and its many features The next four paragraphs describe the remaining chapters and appendix in this Operators Manual Read through these paragraphs to acquaint yourself with the organization of the manual prior to using your new hp Model 3478A Using the 3478A Chapter Il INPUT 2 WIRE N SENSE 14 WIRE Chapter begins where Chapter closes by discussing each function and feature of the 3478A in much more detail This chapter also covers topics such as optimizing reading rates alter nate triggering modes the rear panel features and the display The topics are alphabetically arranged for easy reference Most of the information in CURRENT this chapter will prove to be very helpful when you are remote program ming the 3478A ALL TERM 500vpk A MAX 3A 250V FUSE TEMPERATU
91. h Unknown i Resistance gg pda aa E 25 i 2 6 Self Test Error Messages 29 i 8 1 Home CommandS 39 i 4 1 Accessories lere 63 4 2 Line Voltage Options 64 i 4 3 Specifications 80 A 1 3478A Device Capability 87 A 2 HP IB Worksheet Chapter Meet The 3478A Introduction Your new 34784 is a fully programmable HP IB digital multimeter In an auto matic test or on the bench the 3478A offers 3 1 2 to 5 1 2 digit resolution for measuring dc volts true RMS ac volts 2 and 4 wire ohms and dc and RMS ac current The 3478A offers dc voltage performance from 100 nanovolt sensitivity up to 300 volts full scale true RMS capability up to 300 kHz and resistance measurements from 10040 sensitivity to 30M full scale Its dc and true RMS ac current measuring capability is from 14A sensitivity up to 3A The fast autorange capability of the 3478A allows you to make measurements over a wide dynamic range without sacrificing throughput rates By selecting the number of digits displayed and using the autozero feature the 3478A allows you flexibility in measurement speed and accuracy Up to 71 readings per second can be made with the 3478A in the 3 1 2 digit mode The 3478A has a fast trigger mode which lets you bypass the built in settling time delay to make fast true RMS ac measurements in systems applications The alphanumeric Liquid
92. h th terminal 3 Amp ft 3A 250V FUSE Additior al Feature kosa N Autozero is a function that allows you to enable or disable the inter nal zero correction circuitry Turn ing Autozero off increases the reading rate with a trade off of long term stability SRQ Pressing the Single Trigger key causes the 3478A to take one reading and wait for the next trig ger impulse This impulse can come from either the Single Trig ger key or the External Trigger in put rear pane BNC roca Test Reset performs an internal self test then resets the 3478A to its turn on state Any errors in the self test are noted in the display Chapter Il Using The 3478A Introduction The hp Model 3478A Digital Multimeter is a very powerful bench instrument equally at home in the lab or production areas In the first chapter you saw the very basic features of the 3478A in this chapter you will learn to use those features to solve your measurement needs The detailed operating information in this chapter presents the most comprehensive instruction about all of the multimeter s functions Whether you use your 3478A as a stand alone bench in strument or coupled with a computer for a measurement system the information in this chapter will prove invaluable Detailed Operating Instructions The goal of this chapter is to provide easy to find answers to the vast majority of questions you may have about using your 3478A To this end
93. hat is Voltmeter Complete 34 General Shipping Instructions 74 f Using the Voltmeter Complete Pulse 34 Further Considerations 75 Verification Program and Flow Chart 76 Chapter j H Other ConsiderationsS 28 Safety Considerations 66 Im REMOTE PROGRAMMING o o oo 35 APPENDICES Chapter Page Chapter Page i MEET THE 3478A llle 1 il REMOTE PROGRAMMING Cont d 35 Introduction o o ooo ooo oo 1 Trying Out a Command 35 How to Use This Manual 2 Addressing 0 0000 e eee 36 Simplified Operation 5 6 Sending Instructions to the 3478A 37 Home Commands 39 Chapter Page Programming Hints 40 EE e EHE 34 FGA il 7 Receiving Data from the 3478A 41 Introduction 7 3478A Bus Capabilities 42 Detailed Operating Instructions 7 CLEAR E S Ser ES 43 Operating Characteristics 7 Examples e 43 AUTOZERO s sunk alu eA 8 Comments o occ 43 What is Autozero 8 LOCA KEEN 44 How it Affects Measurements 8 Examples 44 CALIBRATE 5e rre 10 Comments 2x tos dd od A 44 What is Electronic Calibration 10 LOCAL LOCKOUT 44 i Calibrate Enable 10 Example ti ee Sea un 44 E CURRENT uereg rue ri dg wee YE 11 Comments uus
94. in other functions is similar 21 RANGING Cont d 1 H 1 1 1 1 H t 1 1 1 1 l l 1 1 DaT h 300V 27v T i 1 1 e A l 1 i i t 30V i copy m P 30 1V 1 1 1 1 1 1 t 43 jg 1 Y i t RANGE 3V i 270nV Ta oy 1 1 1 D 1 l 300mV i py gt olm i 1 i i 30mV bb i i i 30 Lat 1 i l l gt gt gt gt gt SE 5 E E M C oct O a mM C ND oO ND ND INPUT LEVEL DOWNRANGE POINT UPRANGE POINT 3478A 2 2 Figure 2 2 Autorange Hysteresis Manual Ranging a 2 The 3478A is put in the manual range mode in one of three ways pressing the AUTO MAN Autorange Manual range key which will cause the meter to maintain its present range the UP ARROW key which will cause the meter to go to the next higher range or the DOWN ARROW key to go to a lower range In any case when the 3478A is in the manual range mode the M RNG annunciator is on in the display Pressing the AUTO MAN key restores autoranging The highest or lowest possible range depends on the function selected For exam ple 30 mV is the lowest DC voltage range but 300mV is the lowest AC voltage range If the 3478A were set to the 30mV DC range and you pressed the AC Volts key the meter would default to the nearest valid range i e 300mV The meter will default to the nearest valid range when a function change is made OESHGRED FOR GL Command SYSTEMS See Table 2 4 22 REAR PAN
95. iption of the Hewlett Packard Interface Bus Manual hp part number 59401 90090 The manuals are available through your local hp Sales and Service Office 84 HP IB System Overview The following paragraphs define the terms and concepts used to describe HP IB Bus system operations HP IB System Terms a Address The characters sent by a controlling device to specify which device will send information on the HP IB and which device s will receive that informa tion Addressing may also be accomplished by hardwiring a device to only send in formation or only receive information b Byte A unit of information consisting of 8 binary digits bits c Device A unit that is compatible with the IEEE Standard 488 1978 d Device Dependent An action a device performs in response to information sent over the HP IB The action is characteristic of an individual device and may vary from device to device e Polling This process typically is used by a controller to locate a device that needs to interact with the controller There are two types of polling as follows 1 Serial Poll This method obtains one byte of operational information about an individual device in the system The process must be repeated for each device from which information is desired 2 Parallel Poll This methods obtains information about a group of devices simultaneously The 3478A does not respond to a Parallel Poll Basic Device Communication Capabilities
96. isplay Error Message And Abort Verification Line 70 Go To Subroutine For Pro gram Codes Display Failure Message And Abort Verification Lines 80 90 100 Display Verification Pass ed Message Line 110 End 3478 4F Verification Program and Flow Chart Cont d 414 DUM SELF TEST 42454 CLEAR Test Subroutine 138 DISF SELF TEST 340 SET Go D 16000 456 ON TIMEOUT D GOTO 63a HO A HSWER FROM DUM Lines 410 450 Lines 630 680 n CLEAR Di itialization 428 WRIT 2000 To Timeout 478A Timeout Qcured Inet aa Does Not Respond In 10 42364 OUTPUT 01 E Seconds ed To Respond 499 ENTER El A See OFF TIMEOUT D Dip IF A 4 THEN GOTO Gap 526 IF BIT H H3 1 THEH DISF Line 460 CAL RAM FAILURE Clear D1 Causes The 534 IF BITEBRH 15 1 THEN OISF 3478A To Do A Power RAM FHILURE HOT CAL FAM On Reset 5346 IF EIT H z 1 THEN DIZF ROM FAILURE 55H IF BITEZBH 33 i HEN DISP HD SLOPE ERREUR Line 470 S60 IF BITi H 45 1 THEH DISP Wait 2 Seconds For AD SELF TEST FAILURE Panel On Rasan E STA IF BITA 1 THEH DISP A O LIHE FRILURE Sea DISP Gap OISF SELF TEST FAILED SEE Lines 480 490 THE Check 3478A Error epa DISP 3479A SERVICE MANUAL Register 518 DISP E DISF 3 VERIFICATIO H AEDETEO Ex Eza UIZP STOF quce EJ CLEAR E BEEP PRINT THE OE i m d VICE AT ADDRESS EVALECODLO ATO No SS Display Message And Gap PRIHT CTIE HHY FAILS TO RES SE Return To Main Progr
97. itches 23 Introduction 63 RESISTANCE MEASUREMENTS 25 AcCcessorieS o ooooooooom o 63 Measuring Resistance 25 Initial Inspecti0N 64 How Resistances are Measured 25 Preparation for Use 64 TEST RESET 4 2 ive ote tae 29 Environmental Requirements 67 i What it DoeS o 29 Specifications 67 TRIGGER MODES 30 Interface Connections 67 LIST OF ILLUSTRATIONS Figure Page 2 1 Current Measurements 11 2 2 Autorange Hysteresis 22 2 3 3478A Rear Panel and Switches 24 2 4 Resistance Measurements 27 2 5 Voltage Measurements 33 2 6 Using Voltmeter Complete 34 3 1 Sending Instructions 37 3 2 Instruction Example 38 3 3 Status Register 47 3 4 Status Byte and SRO Mask 47 93 5 Status Byte 50 4 1 Power CablesS 65 4 2 Typical HP IB System Interconnection 68 4 3 3478A Address Codes 69 A 1 HP IB Connector 83 A 2 Interface Connection and Bus Structure 84 LIST OF TABLES Tabie Page 2 1 Operating CharacteristicS 7 2 2 3478A Messages 13 i 2 3 Annunclators 002 ee eee 17 2 4 Valid 3478A Ranges 21 2 5 Nominal currents throug
98. l The value returned should again be 193 bits 7 6 1 This time the SRQ occurred because the SRO Mask was set for bit O Data Ready Do another Serial Poll and notice that the SRQ annunciator goes off momentarily until new data is available The value returned from this second Serial Poll is 65 because bit 7 was cleared by the first poll The previous section on Service Request gave two example programs demonst rating SRQ interrupts Look at the second program FRONT PANEL SRQ Change line 70 to read 70 GOTO 60 and run the program Line 40 sets the SRO mask to front panel SRO Line 1000 performs a serial poll when and only when an SRQ condition occurs e when you press the 3478A SRO key Line 1010 looks at bit 4 of the Status Byte to verify that it was the front panel SRQ key that caused the interrupt 52 TRIGGER Examples TRIGGER 7 TRIGGER 723 Comments If the 3478A has been addressed to listen the TRIGGER message also known as GET for Group Execute Trigger will trigger the multimeter for a new reading If a reading is in progress at the time the TRIGGER message is received the reading will be aborted and a new reading started If a reading is in progress when the TRIGGER message is received there may be a delay up to 1 2 second for the previous A D cycle to be aborted and the new reading to commence 53 ka DI VD OI jmun P PO ra qr _qtoraV gun ar Topics in Advanced Programming The following five programs
99. ll show a value of 129 Looking at Figure 3 5 we can see that the value 129 is equal to the sum of the decimal values of bits O and 7 Bit 7 is true because of the power on reset that occurred Bit O indicates that a measurement has been made and data is ready This step of the exercise simply serves to show that bits in the status register may be true without causing the Service Request message to be sent Remember that when Service Request is sent the SRQ annunciator turns on 51 SPOLL Cont d 2 Now turn the 3478A off On the rear panel find the bank of 8 switches and set switch 3 Power on SRQ to the up 1 position When you turn the 3478A back on the SRO annunciator should be on in the display Now do a serial poll The status byte returned by the 3478A shows a value of 193 This means that bits 7 6 and 1 were true 128 644 1 2 193 Bit 6 is true because of the power on GRO condition Bit 7 is true as in the first step because a power on reset occured Because the Power on SRO switch was SET when the 3478A was turned on it sent the Service Request message SRQ After you do the serial poll the SRQ annunciator will turn off 3 Finally turn the 3478A off and return switch 3 to the down position Turn the 3478A on notice that the SRO annunciator is not on and send it the message MO1 MO1 sets the SRO mask for the data ready condition In just a moment the SRQ annunciator will turn on in the display Again do a serial pol
100. n N SENSE 14 WIRE INPUT 12 WIRE DESKGNEU FOR Gide Commands SYSTEMS F5 Selects DC Current mode also H5 F6 Selects AC Current mode also H6 R suunt 12 3A ALL TERM 2500vpk A MAX 3A 250V FUSE DC OR AC CURRENT SOURCE V Figure 2 1 Current Measurements 11 DISPLAY How it is Used Another of the unique features of the 3478A is the 12 character alphanumeric display with 12 dedicated annunciators The alphanumeric display may be used in one of three modes NORMAL MESSAGE or USER GENERATED MESSAGE The annunciators are used to indicate the current state of the multimeter s features SRO autozero 2 or 4 wire ohms etc Do This press This puts the 3478A in its SELF TEST TEST RESET mode For now just watch the display E and notice the 12 characters in the display and the 12 annunciators Normal In the NORMAL mode of operation the display is used to indicate the results of the measurement whether dc voltage or ohms etc The measurement is displayed in the 2nd through 7th characters in the display The first digit displays the polarity or of the reading The measurement function and in some instances an indication of range is given in the last four characters of the display The max imum display is 303099 with the decimal point appropriately placed for the range Do This press This puts the meter in the dc volts fu
101. n has Bit 5 failed The bit will be set to 1 under this condition Service Request This bit indicates that the 3478A has requested service via the Bit 6 SRQ line The bit is set to 1 whenever one of the events specified for bits O through 5 above occurs at the same time that the corresponding bit in the mask register is set The bit is also set at power on time if the PWR ON SRQ switch on the rear panel is turned on This bit is reset by a serial poll Power on Reset This bit is set to 1 when a power on reset has occurred If Bit 7 switch 3 on the rear panel block of switches is set to the 1 or up position bit 6 will be true and the SRQ message is sent Bit 7 will be cleared if a reset due to the HP IB CLEAR com mand occurs or the TEST RESET key is pressed It is also cleared when the 3478A is Serial Polled All status register bits described above are reset by a Device Clear Message Bits 2 through 7 are also reset by a serial poll if bit 6 was read as a 1 If bit 6 is read as a O indicating that the 3478A was not generating an SRQ no bits are chang ed See also the K command in the Quick Reference Guide Try this simple exercise 1 Reset the 3478A This should be done by cycling the LINE switch Without setting the SRQ mask perform a serial poll on the 3478A Remember to check the command structure for the controller you are using The status byte returned by the 3478A should indicate that bits O and 7 are true Many controllers wi
102. n this line The value OUTPUT Al H is read directly in Mohms EUER ge 250 In this line the value of the resistor is R3 R1 R2 7CR1I R2 d OUTPUT Al DaRz Ri718 6 CLEAR DISP THE RESISTANCE IS R3 10 6 MOHHSZ END 55 displayed on the hp 85 display dBm MEASUREMENTS The dBm Program is used to calculate a power ratio using a BOU impedance as the reference The dBm equation is dBm 10 LOG X2 R 1mw where X is the measured value R is the impedance reference 50Q s and 1mw is the OdBm reference lines Description 30 This line uses the H2 Home command to 18 dBm MEASUREMENT set the 3478A to the ac volts mode T1 is 20 HP 85 VERSION internal trigger pr HIER o ode 40 The ac voltage measurement is input to E D Ee the hp 85 in this line 30 P iBXL GcB 27S8 88i Sc GE p 50 This line performs the dBm conversion 88 END 60 Line 60 displays the dBm value on the hp 85 70 This line causes the program to return to line 40 for another measurement 56 MAXIMUM READING RATE The maximum possible reading rate is with 3 1 2 digits selected autozero off display off manual ranging the line frequency switch 3478A rear panel set to the 60Hz position and positive dc voltages current and resistance measurements Remember though there is a settling delay on the two highest ohms ranges The program in the following figure sets the 3478A for these conditions with two exceptions First you must m
103. nction manual range mode Note the MAN M RNG annunciator in the display press Press these keys several times and watch the display as the decimal point o OR 9 moves across and as the display in dicates MVDC for milli volts DC and then VDC for Volts DC The display is always read directly Do the same in the 2 wire ohms mode Watch as the display indicates OHM KOHM kkil ohms and MOHM Meg ohms 12 DISPLAY Cont d Abnormal Multimeter Readings If a reading is larger than a particular range can display the display will indicate an OVLD with the measurement function and decimal point still displayed If the A D convertor is inoperative the display will indicate A D TEST FAIL or A D LINK FAIL The 3478A will continue to try to make a reading and if it suc ceeds it will display the reading Message It was demonstrated in the last two paragraphs that the 3478A is capable of displaying error messages There are several other messages the 3478A may display For example i Do This press T The display should now indicate ENABLE CAL This message in Jo dicates that the calibration switch must be set to the calibrate position before the instrument can be calibrated OR ADRS pe The display now shows the HP IB ad dress of the 3478A L E These are two more examples of messages which the 3478A may display Other possible messages will fall into
104. not respond to the front panel keys 3478A not in REMOTE mode turn the multimeter off and per form the following steps 1 Remove the HP IB connector External Trigger Voltmeter Complete and power cables 2 Check the Line Voltage option marking on the rear panel of the 3478A to ensure that it is set to the correct nominal line voltage in your area i e 110 120 220 or 240 Vac 3 Ensure that the correct power line fuse is installed and that it is intact 4 Check the AC power cord and plug it into the AC receptacle on the 3478A 70 5 Turn the 3478A on Watch the display At turn on the multimeter will display SELF TEST then the HP IB address and then start taking readings in the dc volts mode If any part of the self test should fail an error message will be shown in the display instead of the HP IB address 6 If the display does not return or if the self test fails again the 3478A re quires service Notify your local hp Sales and Service Office for specific informa tion on where to send the instrument for repair Remote At the end of this chapter is a program that you can use to verify the operational readiness of the 3478A Although the program was written for the hp 85 com puter the attendant flowcharts may be used to convert the program to run on other computers The program was not designed to troubleshoot the 3478A but the information gathered by running the program can be a great help in troubleshooting
105. nts in tight areas where the probe must not slip What you do is this press the Single Trigger key and position your finger to press the key again You can then place the probe press the Single Trigger key and then remove the probe all without taking your eyes off of the probe With the probe safely removed the measurement is still held on the display 30 TRIGGER MODES Cont d When the 3478A is in the Single Trigger mode and you attempt to change ranges or change function the left hand portion of the display will go blank with the ex ception of the decimal point until another trigger impulse is received DESIGNED FOR Command SYSTEMS T3 Selects the Single Trigger Mode External Trigger The external trigger mode is enabled by the single trigger key and is identical to the single trigger mode except that the triggering impulse is applied to a BNC con nector on the rear panel of the 34784 The External Trigger input is TTL logic compatible or may be actuated by a simple switch closure The 3478A is trig gered on the negative edge of the TTL pulse which must be a minimum of 100nS duration If a trigger pulse is received while a reading is in progress the impulse is ignored uge Command SYSTEMS T2 Selects the External trigger mode Associated HP IB Commands T4 Selects the Trigger Hold Mode T5 Fast Trigger Same as T3 except that the settling delay is omitted on AC Volts and current and the two highest ohms ranges
106. o RO Pi i na Jn OH itt 5 e m c 5 GI had o Se LA OO LD Sa GI Gi mi Verificatio i 3474 WERE IW CH GI x LA ee Fm bp et m ka AU CHIC CH CH en dl A T mm IT e m UH EAE DEREN Cry CC aet DE VERIFICATION D C D E Mm EK a hi I TZ T Zo PED EHD DISP 3479A UERIFICHTION PROGRAM DISF C Fo 1 REMOVE ALL IHZTE L TI rt L HTS FROM THE EUS MCEPT 3472A sp m SCH HOT PRESS AHY 4 54 KEYS CUEIHG THIS TEST DISP UNTIL IHSTEUCTED Sa a Se en CH DISP 2 REMOVE ALL INPUT ABLES FROM THE 347 CH fA ee CI UI bed o et Ta em T TX A O A UD ta 3103 TEST PROGRESS IS SHON THE DISPLAY ERRORS ARE H OH P THE PRINTER nm ur bust a Daz HA fm aa ED m FRESS CE DI GHTI KEY DISP TO GEGIH PRISE CLEAR DISP KEE DISP d Op 2 e DISP E DIZP PE FHO O LIHEA KEY Dli r2az DH ERROR GOTO Zen HPUT 1 gira THEH O1 4 DIS 16 CH CH ran D won CT al ri CH 2 Tn Ta Wn r3 pa E A rA A DEI ta kat ea OOTP OG Wasp Dm 1D IHVHLID IHFIT t EEEF te 7D T WC 1 en n A Tei HE e na A We ke e C3 c TT os Xu m c mo o unn n Program and Flow Chart Lines 10 40 Program Title and Simple Overhead Line 50 Go To Subroutine For In structions 3478A HP IB Address In Variable D1 Line 60 Go To Subroutine For Self Test D
107. o Ltd Elcom Research Building 2538 Sukhumvit Ave Bangchak BANGKOK Tel 393 2387 393 0338 Telex TH8 1160 82938 81038 Cable UNIMESA Bangkok AC E M Bangkok Business Equipment Ltd 5 5 6 Dejo Road BANGKOK Tel 234 8670 234 867 1 234 8672 Cable BUSIQUIPT Bangkok D TRINIDAD amp TOBAGO Caribbean Telecoms Ltd DO Box 732 50 A Jermngham Avenue PORT OF SPAIN Tel 624 4213 624 4214 A CM EMP TUNISIA Tunisie Electronique 31 Avenue de la Liberte TUNIS Tel 280 144 EP Corema 1 ter Av de Carthage TUNIS Tel 253 821 Telex 12319 CABAM TN M TURKEY Teknim Company Ltd Riza Sah Pehievi Caddesi No 7 Kavaklidere ANKARA Tel 275800 Telex 42155 E EMA Muhendislik Kollektif Sirketi Mediha Eldem Sokak 41 6 Yuk sel Caddesi ANKARA Tel 17 56 22 Cable Ematrade M UNITED ARAB EMIRATES Emitac Ltd P O Box 1641 SHARJAH Tel 354121 354123 Telex 68136 EM P C UNITED KINGDOM see GREAT BRITAIN NORTHERN IRELAND SCOTLAND UNITED STATES Alabama Hewlett Packard Co 700 Century Park South Suite 128 BIRMINGHAM AL 35226 Tel 205 822 6802 CM CS MP Hewlett Packard Co P O Box 4207 8290 Whitesburg Drive S E HUNTSVILLE AL 35802 Tel 205 881 4591 CM CP E M Alaska Hewlett Packard Co 1577 C Street Suite 252 ANCHORAGE AK 99510 Tel 206 454 3971 CM CS Arizona Hewlett Packard Co 2336 East Magnolia Street PHOENIX AZ 85034 Tel 602 273 8000
108. o send the TRIGGER Message Group Execute Trigger Bus Management Lines Bus Management Lines ATN IFC SRQ REN EOI ATN IFC SRO BEN EOI T 3 e ee al RU E T Sent on Data Lines Sent on Data Lines U 7 oct010 Z T ie TT T A Universal Unlisten be 3478A Listen Address Universal Unlisten Trigger Command Controller Talk Address Controller Talk Address 3478A Listen Address then Ao Remote Message ATN IFC SRQ REN EO on EA em To Enter the REMOTE Mode F F Xx T X E Bus Management Lines Sequence on Data Lines ANI ec SRQ RENI Ec EO Instrument Sent on Data Lines U7 Universal Unlisten L 3478A Listen Address Controller Talk Address Program Codes Data Message 3478A to Controller or Other Device s To Remain i in the REMOTE Mode i from the 3478A to the controller first Bus Management Lines To send Bus Management Lines ATN IFC SRQ REN EO ATN IFC SPOT REN EOI FAE i X X ix GU FS k Sequence on Data Lines ws Local Message Universal Unlisten Controller Listen Address To enter the LOCAL Mode ess 3478A Talk Address Bus Management Lines ATN IFC SRQ REN EOI then Tea X40 E Sent on Data Lines Bus Management Lines SE EE U 7 octOO1 ATN IFC SRQ REN EOI T DOCE UM d GG WER Universal Unlisten Go to Local instruction 1 34784 Listen Address M E ME i FiF Xix x Controller Talk Ad
109. of other HP IB activity and is sent on a single Interface Bus line called REN see Appendix A Some controllers set the REN line true at power on or when reset which has the same effect as sending the Remote message with only the interface select code Le REMOTE 7 Before any instru ment will actually go into the Remote state it must be addressed Therefore when the 3478A is first addressed such as OUTPUT 723 it will actually go to the remote state 45 REQUIRE SERVICE SRQ Another important feature of the 3478A is that you can program it to interrupt the controller when certain conditions are met Of course the controller must also be programmed to respond to the interrupt The Require Service SRQ message is used to implement this and is independent of all other HP IB activity SRQ is sent on a single Interface Bus line called the SRO line see Appendix A The 3478A MUST BE PROGRAMMED for the interrupt before the interrupt will take place The following list gives the possible causes of interrupt that the 3478A can be pro grammed for 1 Power on Reset The 3478A will interrupt the controller when the 3478A power is turned on it received a Device CLEAR or Selected Device CLEAR or the 3478A was reset 2 CAL Failure The 3478A will interrupt the controller if an attempted calibra tion failed 3 Front Panel Keyboard You can use the front panel SRO key on the 3478A to interrupt the controller 4 Hardware Error If a hard
110. ommand See Chapter HI k 29 TRIGGER MODES What is Triggering Triggering is simply the process that causes the 3478A to take a reading There are three basic triggering modes available on the 3478A These three modes are described after we look at the trigger indicator Trigger Indicator The decimal point that is farthest right in the display will blink every time a reading is completed If a colon or comma is placed there by a remote operation D2 command see Chapter lil the display will alternate between a comma and a colon i INT Internal Trigger In the internal trigger mode the 3478A triggers itself to take readings at the max imum possible rate This mode is automatically selected at instrument turn on and after performing Self Test A settling delay has been added before each A D con version in the ac volts and current and the two highest ohms ranges to ensure ac curate readings DESIGNED FOR 115 Command SYSTEMS T1 Selects the internal trigger mode Single Trigger The single trigger mode allows you to manually trigger the voltmeter from its front panel The first time you press the Single Trigger key the 3478 will take one reading display the results and go to the single trigger mode Subsequently each time the key is pressed the multimeter will make one reading display the result and then sit idle waiting for another trigger This sample and hold feature is useful when you re taking measureme
111. one by pressing a front panel button and there is ab solutely no disassembly required It is beyond the scope of this section to present the entire calibration procedure For complete calibration information refer to the 3478A Service Manual hp part number 03478 90001 Briefly Electronic Calibration is done by applying a known voltage or resistance or current to the voltmeter and telling it the exact value of that voltage The voltmeter then takes ten readings and compares the average of those readings to the known value A CALIBRATION CONSTANT is calculated to correct the reading to the known value and then stored in the voltmeter s memory These Calibration Constants are generated for each range and function of the meter All subsequent measurements are corrected by the constants The Calibration Cons tant memory is backed up by a long life battery to maintain the constants when power is turned off Calibrate Enable On the front panel of the 3478A is a small rotary switch labeled CAL This switch when rotated so that the slot is vertical enables the calibration procedure of the 3478A This switch should not be turned except when qualified service trained personnel are to perform the calibration procedures Enabling the CAL switch may cause loss of calibration if proper procedures are not followed careful ly DESIGNED FOR LD Commands SYSTEMS C Calibrate see the 3478A Service Manual 10 CURRENT Measuring Current
112. one of three categories Table 2 2 3478A Messages ERROR MESSAGES see Self Test U C RAM FAIL The 34784 has failed its internal RAM self test U C ROM FAIL The 3478A has failed its ROM self test indicating an error in the ROM CAL RAM FAIL An attempt to write to the calibration RAM during calibration was unsuccessful UNCALIBRATED The CAL RAM has an incorrect checksum The calibration of the 3478A is suspect 13 DISPLAY Cont d Table 2 2 3478A Messages Cont d A D LINK FAIL The internal processor is unable to communicate with the A D convertor A D SLOPE ERR The A D convertor is not able to converge upon a result properly A D TEST FAIL The A D convertor has failed its self test CALIBRATION MESSAGE see the 3478A Service Manual CALIBRATING The CAL key has been pressed and a calibration is in progress CAL ABORTED Either an invalid key was pressed an overload was detected or an A D convertor error was detected The calibration is aborted CAL FINISHED A calibration cycle has been successfully completed ENABLE CAL The CAL ENABLE switch must be turned to the CAL vertical position in order to do a calibration VALUE ERROR The 3478A is unable to calibrate to the requested value This message would result if a A zero calibration is attempted and the 3478A reads a raw value outside the range of 50000 to 40000 assumes 5 1 2 digit mode A gain calibration is attempted with a negative
113. ontact your local sales office for information regarding locations where HP support is available for specific products HP distributors are printed in italics ANGOLA Telectra Empresa T cnica de Equipamentos El ctricos S A R L R Barbosa Rodrigues 4 1 1 DT Caixa Postal 6487 LUANDA Tel 35515 35516 A EMP ARGENTINA Hewlett Packard Argentina S A Avenida Santa Fe 2035 Martinez 1640 BUENOS AIRES Tel 798 5735 792 1293 Telex 122443 AR CIGY Cable HEWPACKARG A E CP P Biotron S A C Ly M Avenida Paseo Colon 221 9 Piso 1399 BUENOS AIRES Tel 30 4846 30 1851 30 8384 Telex 33 17595 BIONAR Cable BIOTRON Argentina M Fale S A Electronica Bartolomeu Mitre 833 1036 BUENOS AIRES Tel 74 41011 74 49277 74 43459 Telex 18137 22754 P AUSTRALIA Adelaide South Australia Pty Ltd Hewlett Packard Australia Div Lg 153 Greenhill Road PARKSIDE S A 5063 Tel 272 5911 Telex 82536 Cable HEWPARD Adelaide A CM CS E MS P Brisbane Queensland Office Hewlett Packard Australia Pty Ltd 5th Floor Teachers Union Building 495 499 Boundary Street SPRING HiLL Queensland 4000 Tel 229 1544 Telex 42133 Cable HEWPARD Brisbane A CM CS E MS P Canberra Australia Capital Office Hewlett Packard Australia Pty Ltd 121 Wollongong Street FYSHWICK A C T 2069 Tel 804244 Telex 62650 Cable HEWPARD Canberra A CM CS E MS P Melbourne Victoria Office Hewlett Packard Australia Pty L
114. ounterclockwise The terminal and fuse will 68 protrude from the front panel Remove the terminal and fuse replace the fuse with a 3A 250V rated fuse hp part number 2110 0003 Return the terminal and fuse to the front panel Power Line Fuse The power line fuse is located on the rear panel of the 3478A in the lower right corner To replace the fuse turn the multimeter s power switch off and remove the power cord from the rear of the instrument With a small flatblade screwdriver rotate the fuse terminal counterclockwise Replace the fuse with the appropriate fuse as shown in Table 4 2 Reinstall the fuse and terminal and apply power 3478A DVM INSTRUMENT NOT USED ADDRESS Shown at Factory 1 Default Address 23 This number 0 is called the 12345678 Primary Address 1 50Hz 16 4 1 0 60Hz BOWER ON SRQ ASCII Code Character Address Switches 5 bit Listen Talk A4 A5 A6 A7 A8 Decimal Code SP 0 0 0 0 SCH 00 A 0 0 0 o 1 01 Se B 0 o 0 1 O0 02 D C 0 o 0 1 1 i 03 D 0 0 1 0 o 04 E 0 o 1 0 1 05 8 F i 0 0 1 1 o 06 G 0 o 1 1 1 j 07 H e 1 0 0 0 08 l 0 1 10 0 1 09 j J 0 1 o 1 o 10 Kio t 1 1 11 L o 1 1 0 0 12 M 0 1 1 0 1 13 N o 1 1 1 9 14 oO 0 1 1 1 1 15 0 Pop d 6 6 0 0 16 1 Q 1 D 0 0 1 17 2 H 0 0 1 O 18 3 S 1 0 9 1 1 19 4 T j 1 o 1 0 0 20 5 U i 1 9 1 6 1 21 6 V ji 1 9 1 1 0 22 7 Ww 1 0 1
115. own in Figure 4 2 in which system interconnection is made by three interface cables The ends of the cables have both a male and a female connector to enable connections to other instruments and cables As many as 15 instruments can be connected by the same interface bus However the maximum length of cable that can effectively be used to connect a group of instruments should not exceed 2 meters 6 5 feet times the number of instruments to be connected or 20 meters 65 6 feet total whichever is less minimam mm Figure 4 2 Typical HP IB System Interconnection Address Selection The HP IB address of the 3478A is determined by the setting of the five right most switches on the rear panel These switches are read at power on whenever the ADRS key is pressed or whenever an HP IB CLEAR message is received over the bus Turning on up all five switches selects the 3478A Talk Only mode The 3478A normally leaves the factory with the address switches set to decimal code 23 The corresponding ASCII code is a listen address code of 7 and a talk code of W Refer to Figure 4 3 for the factory address switch setting Fuse Replacement Amps Terminal Fuse The Amps terminal fuse is located physically inside the Amps A terminal on the multimeter front panel To replace the fuse first remove the cable from the Amps terminal and then turn the power off to the multimeter Use the side slots on the A terminal to rotate the terminal c
116. r after each completed measurement data ready This means that the controller doesn t waste valuable computing time waiting for measurement data but pro ceeds with its work until interrupted To enable the data ready feature on the 3478A bit O on the SRO mask must be set Remember that bit O will be true in the status register anytime data is ready but for the SRO to occur the mask must be set The bit pattern for the mask would look like bit 5 4 3 2 1 O value O O O O O 31 Ll O 1 O1 is the octal representation see also Figure 3 4 Consequently we would use the command OUTPUT 723 M01 to set the mask for Data Ready Therefore whenever the 3478A has data ready it will interrupt the controller via the SRQ line The controller will only be interrupted if bit O is true meaning that data is ready Bits 1 through 5 will not interrupt the controller if they go true because the mask was not set for those bits When data becomes ready the SRQ annunciator turns on in the display and remains on until the con troller responds by doing a serial poll executing the CLEAR command outputting the K instruction or entering a measurement from the 3478A Line 40 50 CATA READY EXAMPLE he 85 VERSION 3478A AT ADDRESS 723 60 OUTPUT 723 kMai1 UN INTR 7 GOSUB 1000 ENABLE INTR 7 8 The body ot the rFrosram 20 es here 70 990 END P SPOLL 7T233 STATUS 7 1 S A 1000 ENTER 7223 R DISP E RETURN 1010 1020
117. r range for the measurement Press any of the keys to select the manual range mode Note the M RNG annunciator in the display The Auto Man key will return the meter to autorange Pressing this key tog gles between Auto and Manual ranging Upranging Downranging 3478A MULTIMETER HEWLETT RACKARD Blue Key shift pressed before another key executes the above that key function shown 2win 4 WIRE f ai E used to select special operating features of the 3478A The next two chapters provide a detailed explanation of These keys are these keys The blue shift key allows for selecting the SHIFTED functions of the bot tom row of keys You can always tell when you have pressed the Shift key the SHIFT annunciator will appear in the display It will disappear when the function is executed or shift is again pressed internal Trigger is selected by this key In this mode the 3478A triggers itself for the fastest possible reading rate INT TRIG OSense f H N SENSE 16 WIRE ALL TERM 500Vp MAX Ma SGL TRIG These terminals are used for the voltmeter sense leads when mak ing 4 wire ohms measurements Inpu These are the wv 7 2 wire ohms input source current termi INPUT 12 WIRE Front Re When this switch is oe panel input terminals If the switch is in terminals are used lg ELI This is the Amps and is used wit
118. r reception of the B com mand it will output five bytes which indicate its currently programmed state This command also clears the error register byte 4 The meaning of the five bytes is Byte 1 Function Range and Number of Digits If Octal value of bits 7 6 5 then DC Volts then AC Volts then 2 wire Ohms then 4 wire Ohms then DC Current then AC Current then Extended Ohms Il NOP WD 3 If Octal value of bits 4 3 2 1 then 30mV DC 300mV AC 30 ohm 300mA AC or DC Extended Ohms 2 then 300mV DC 3V AC 300 ohm 3A AC or DC 3 then 3V DC 30V AC 3K ohm 4 then 30V DC 300V AC 30K ohm 5 then 300V DC 300K ohm 6 then 3M ohm 7 then 30M ohm IF Octal value of bits 1 0 1 then 5 1 2 digit mode 2 then 4 1 2 digit mode 3 then 3 1 2 digit mode Byte 2 Status Bits Bit 7 Always zero Bit 6 1 then External trigger enabled Bit 5 1 then Cal RAM enabled Bit 4 1 then Front Rear switch is in the front position Bit 3 1 then 3478A is set up for 50Hz operation Bit 2 1 then Auto Zero is enabled Bit 1 1 then Auto Range is enabled Bit O 1 then Internal trigger is enabled Byte 3 Serial Poll Mask SRQ Bit 7 1 then PON SRQ switch was on the last time power was turned on or a device clear message was received Bit 6 Always zero Bit 5 1 then SRO if CAL procedure failed Bit 4 1 then SRQ if keyboard SRQ is pressed Bit 3 1 then SRQ if
119. rence Guide that you can tear out and keep with your 3478A Addressing Do This i press aoas The 3478A will display its HP IB ad E dress in the form HPIB ADRS XX XX represents the actual address which is factory preset to 23 E CTI EE Each instrument that you connect to the interface bus has a unique address and the 3478A is no different The address provides a way for the controller to send or receive data from one instrument on the bus when actually there are several instruments connected together In the previous example where you displayed your name we used the statement OUTPUT 723 The 723 refers to the controller interface select code isc which is 7 and the 3478A factory preset address which is 23 If you need to change the address of the 3478A refer to the installation information in Chapter 4 All the examples in this chapter assume that the 3478A will be addressed at 723 which is also called the device select code dsc When the controller tells a particular instrument to talk i e send data over the In terface Bus we say that the instrument has been Addressed to Talk Likewise when the controller tells an instrument to listen i e receive data or instructions from the Bus the instrument is said to have been Addressed to Listen The 3478A is capable of both talking and listening or it may be set to Talk only in which case it cannot listen to instructions or data coming over
120. rezentanta Boulevard Nicolae Balcescu 16 BUCURESTI Tel 130725 Telex 10440 SAUDI ARABIA Modern Electronic Establishment DO Box 193 AL KHOBAR Tel 44 678 44 813 Telex 670136 Cable ELECTA AL KHOBAR CEMP Modern Electronic Establishment P O Box 1228 Baghdadiah Street JEDDAH Tel 27 798 Telex 401035 Cable ELECTA JEDDAH CEMP Modern Electronic Establishment DO Box 2728 RIYADH Tel 62 596 66 232 Telex 202049 C EMP SCOTLAND Hewlett Packard Lid Royal Bank Buildings Swan Street BRECHIN Angus Scotiand Tel 3101 3102 CM CS Hewlett Packard Ltd SOUTH QUEENSFERRY West Lothian EH30 9TG GB Scotland Tel 031 3311000 Telex 72682 A CM E M SINGAPORE Hewlett Packard Singapore Pty Ltd P O Box 58 Alexandra Post Office SINGAPORE 9115 6th Fioor Inchcape House 450 452 Alexandra Road SINGAPORE 0511 Tel 631788 Telex HPSGSO RS 34209 Cable HEWPACK Singapore A CP E MS P SOUTH AFRICA Hewlett Packard South Africa Div Ltd P O Box 120 Howard Place Pine Park Center Forest Drive Pinelands CAPE PROVINCE 7450 Tel 53 7955 53 7956 53 7957 Telex 57 0006 A CM CS E MS P Hewlett Packard South Africa Pty Ltd PO Box 37066 Overport DURBAN 4067 Tel 28 4178 28 4179 28 4110 CM CS Hewlett Packard South Africa Ply Ltd P O Box 33345 Glenstantia 0010 TRANSVAAL 1st Floor East Constantia Park Ridge Shopping Centre Constantia Park PRETORIA Tel 98 1126 or 98
121. rnings and cautions must be follow ed Safety Symbols used on the instrument or in the manual include the following WARNING The WARNING sign denotes a hazard It calls attention to a procedure practice condition or the like which if not cor rectly performed or adhered to could result in injury or death to personnel CAUTION The CAUTION sign denotes a hazard It calls attention to an operating procedure practice condition or the like which if not correctly performed or adhered to could result in damage or destruction to all or part of the product NOTE The NOTE sign denotes important information It calls at tention to a procedure practice condition or the like which is essential to highlight N Instruction Manual Symbol the product will be marked with this symbol when it is necessary for the user to to refer to the instruction manual in order to protect against damage to the instrument Indicates dangerous voltage terminals fed from the interior by voltage exceeding 1000 volts must be so marked Ne Alternating current Direct current 66 Environmental Requirements When the 3478A is calibrated careful note should be taken of the ambient temperature In order to meet and maintain the specifications listed in Table 4 3 the 3478A should be operated within 5 C 9 F of the calibration temperature also called the reference temperature As it comes from the factory the 3478A should be operated within an
122. s arranged in alphabetical order deal with HP IB commands see Appendix A and the way the 3478A responds to them Refer to the I O pro gramming manual of your controller for specific information on syntax and actions taken by the HP IB interface when sending the message The examples given app ly to the hp 85 9835 9845 computers except where noted 42 CLEAR Examples CLEAR 7 device clear CLEAR 723 selected device clear Comments Upon receiving the CLEAR message the 3478A will be placed into its test reset routine The routine starts with the 3478A performing its internal self test and reading its rear panel HP IB address switches Any errors in the self test will be noted in the voltmeter display and will cause the hardware error bit to be set in the status register and the appropriate bits to be set in the error register If there are no errors the HP IB address will be displayed for approximately 2 seconds The power on state for the 3478A is DC Volts function Autorange Internal Trig ger Autozero On and 5 1 2 digit mode 43 LOCAL Examples LOCAL 7 LOCAL 723 Comments The LOCAL 723 message clears the 3478A from the REMOTE operation mode and reenables front panel control Pressing the front panel LOCAL key ac complishes the same thing provided the key has not been disabled by the LOCAL LOCKOUT Message LOCAL 7 removes every instrument on interface 7 from the remote mode If the 3478A is in Remote wi
123. s 750 770 Enable SRQ interrupt Lines 780 810 Beep Every 10 Seconds Until Key Is Pressed Line 830 Status Command To Clear SRQ Register Lines 900 930 SRO Key Not Pressed Something Else Caused SRQ Verification Aborted 840 860 Test Bit 4 Of Status Byte 3 For Front Panel sRQ Display Front Panel SRQ Passed Lines 940 1480 Program Codes Test Lines 990 1020 3478A Accepted lllegal Syntax Verification Aborted Lines 1030 1050 3478A Generated SRO For Illegal Syntax and Flow Chart Cont d Lines 1060 1380 Test Program Codes For Autozero Range Func tions Display Trigger and Home Commands Lines 1070 1600 3478A Generated Syntax Error For Valid Syntax Verification Aborted Lines 1090 1160 Test Autozero Function And Range Test Display Commands ines 1290 1320 Test Trigger Commands Lines 1170 1200 Test For Number Of Display Digits Lines 1340 1370 Test Home Commands Lines 1390 1480 Readings Test 79 Lines 1380 1420 Test For 300 VDC Range Zero Prin Verifi Zero Error Not Aborte Print Ohms Overload Er ror Verification Not Aborted Lines 1440 1460 Test For Ohms Overload Lines 1470 1490 Verification Complete Return To Main Program 3478 4F Table 4 3 Specifications DC VOLTAGE Input Chara
124. s that are often noisy non periodic or non sinusoid The RMS converter will accurately measure the True RMS value of sawtooth or triangle waveforms squarewaves or low repetition rate high crest factor ratio of peak to RMS pulse trains 32 VOLTAGE MEASUREMENTS Cont d RMS measurements are made by calculating the instantaneous square of the input signal averaging it and taking the square root of the result This provides a DC voltage that is proportional to the RMS value of the waveform A DC voltage measurement is then made by the A D converter it should be noted that the AC voltmeter accuracy is specified only for inputs greater than 10 of full scale Hence the specified range is 30 millivolts to 300 volts The 300 millivolt range is useful for lower accuracy readings down to 1 millivolt Up to several hundred counts of residual offset may be seen on the 57 digit display with the input shorted UESHsMED G3 Command SYSTEMS F2 Selects the AC Volts mode also H2 INPUT 2 WIRE N SENSE 4 WIRE Qc 300Vzz MAX ef 3AN MAX ALL TERM 500Vpk MAX 3A 250V FUSE DC OR AC VOLTAGE SOURCE 3478 2 5 Figure 2 5 Voltage Measurements 33 VOLTMETER COMPLETE What is Voltmeter Complete The Voltmeter Complete BNC connector on the rear panel of the 3478A provides a pulse at the completion of every A D cycle This pulse is used to indicate that the 3478A is ready to output
125. s to its turn on state Do This This initiates the functional tests of the digital circuitry in the 3478A The SELF press TEST TEST starts by turning every segment in C SCH the display on except the top dot on the colon These segments will remain on for as long as the Self Test button is held down When the button is released the display will remain for ap proximately 2 seconds as the self test is performed It will then display SELF i TEST OK or an appropriate error message If the self test passed the HP IB address will be displayed and the 3478A returns to its power on state If an error was detected and the error message displayed the HP IB address will not be displayed but the 3478A will attempt to operate normally Table 2 6 Self Test Error Messages U C RAM FAIL This indicates that the micro computer s internal RAM not CAL RAM has failed its self test U C ROM FAIL The 3478A internal ROM has failed its self test This indicates an error in the ROM UNCALIBRATED The random access memory that contains the calibration constants has an in correct checksum The calibration of the 3478A is suspect A D TEST FAIL The A D converter has failed its self test A D LINK FAIL The microcomputer is unable to communicate with the A D converter For all failures refer to the 3478A Service Manual DESIGNED Lee Command d SYSTEMS Use the HP IB CLEAR c
126. simply keeping the temperature of the 3478A at a fixed value you can nearly double your reading rate by turning autozero off without adverse effects Although the 3478A is slightly less accurate the faster reading rate may be worth it In addition any range or function change that takes place is automatically accompanied by an autozero update which removes any ac cumulated offsets If the measurement environment is quiet enough to disregard NMR then only accuracy and resolution are the measurement speed factors and autozero may be turned off D Other Factors influencing the Reading Rate 1 You can speed the reading rate by selecting a fixed range instead of allowing the multimeter to autorange every reading 2 AC voltage measurements have a built in 600mS settling time Resistance measurements can be made as fast as DC voltage measurements except on the 3Mohm and 30Mohm ranges where a settling time 30mS and 300mS respective ly is needed for stable measurements The T5 Fast Trigger command HP IB is the same as the T3 command except that the delay is omitted If more than one reading is required because of autoranging etc the delay will occur normally 3 Consider the time it takes to transfer data over the HP IB For example the TRANSFER command is much faster than the ENTER command on the hp 85 computer 4 The maximum possible reading rate is with 3 1 2 digits displayed autozero off any DC voltage function 60 Hz power sele
127. tches 4 through 8 are used to select the HP IB talk listen address for the 3478A The factory preset positions for these switches are from left to right up down up up up for a selected address of 23 In order to select the talk only mode all five switches must be in the on or up position For more information on the HP IB address switches refer to Appendix A 23 Rear Panel Input Terminals N SENSE 4 WIRE External Trigger Input HP 18 Connector ee PWR ON SRO jot uu e ei edei 100v 120v 220V 240V v LINE 5 10 48 66Hz V ADRS 25VA MAX 1 50Hz 0 60Hz 250mA T25mA INPUT pu h 5 q Voltmeter ni Complete e S Y Output k a AE N 2i ind WP e e SS I N Power Line ee e PWR ON SRQ Option Label 1 50Hz 0 60Hz Figure 2 3 3478A Rear Panel and Switches 24 RESISTANCE MEASUREMENTS Measuring Resistance The 3478A is capable of measuring resistance from 30 milliohm to 30 Megohms in seven ranges Resistance measurements may be made in either 2 or 4 wire ohms configuration The illustrations in Figure 2 4 show how resistance measurements are made A known current is supplied by the 3478A and flows through the unknown resistance The DC voltmeter measures the attendant voltage drop The 3478A is factory calibrated in the 4 wire ohms mode If most or all of your resistance measurements will be made in the 2 wire ohms mode the 3478A may be recalibrated in the 2 wire ohms mode See the 3
128. td 31 41 Joseph Street BLACKBURN Victoria 3130 Tel 89 6351 Telex 31 024 Cable HEWPARD Melbourne A CM CP E MS P Perth Western Australia Office Hewlett Packard Austalia Pty Ltd 141 Stirling Highway NEDLANDS W A 6009 Tel 386 5455 Telex 93859 Cable HEWPARD Perth A CM CS E MS P Sydney New South Wales Office Hewlett Packard Australia Pty Ltd 17 23 Talavera Road NORTH RYDE N S W 2113 PO Box 308 Tel 887 1611 Telex 21561 Cable HEWPARD Sydney A CM CP E MS P AUSTRIA Hewlett Packard Ges m b h Grottenhofstrasse 94 Verkaufsburo Graz 8052 GRAZ Tel 21 5 66 Telex 32375 CM C E Hewlett Packard Ges m b h Wehlistrasse 29 PO Box 7 A 1205 VIENNA Tel 222 35 16 210 Telex 135823 135066 A CM CP E MS P BAHRAIN Green Saion DO Box 557 BAHRAIN Tel 5503 Telex 884 19 P SALES amp SUPPORT OFFICES Arranged alphabetically by country Wael Pharmacy DO Box 648 BAHRAIN Tel 54886 56123 Telex 8550 WAEL GJ M BELGIUM Hewlett Packard Belgium S A N V Blvd de la Woluwe 100 Woluwedal B 1200 BRUSSELS Tel 02 762 32 00 Telex 23 494 paloben bru A CM CP E MP P BRAZIL Hewlett Packard do Brasil l e C Ltda Alameda Rio Negro 750 ALPHAVILLE 06400 Barueri SP Tel 421 1311 Telex 011 23602 HPBR BR Cable HEWPACK Sao Paulo A CM CP E MS Hewlett Packard do Brasil Let Ltda Avenida Epitacio Pessoa 4664 22471 RIO DE JANEIRO RJ Tel 286 0237 Telex 021 21905 HPBR
129. ternal 10 Mohm resistor and Rt is the measured value of the parallel combination The test leads should be a very short shielded twisted pair to not pick up radiated noise A program that will make the necessary measurements perform the calculations and display the value for the unknown resistor is given in the following figure EXTENDED OHMS EXAMPLE i he 85 VERSION m CLERE Lines Description Hi r2s R 10 40 These lines title the program clear the E fa p DUE dE d hp 85 display and set the variable A1 to FLE E DISP 723 which is the HP IB address of the DISP Extended ohms is a 2 4 3478A Ee O resiii 50 140 These lines are used to make the measure ances ment of the internal 10 Mohm resistor DISP above 34 Mohmz amp DIS The actual measurement is made in line P rs 130 and input to the hp 85 in line 140 DISP Open the 3478A input t Line 50 displays a message on the 3478A P PEOR Eegen TO BEGIN display to open the input terminals 5 150 220 In this set of program lines the measure aun s ment of the parallel resistor combination is e EU Ma made Line 210 causes the 3478A to take OUTPUT AL DZRDD RESISTOR the measurement and line 220 inputs the CLEAR DISP Connect resist measurement to the hp 85 ance to be 230 Line 230 uses the formula above to D ar ER calculate the value of the unknown DISP terminals resistor HIA amp DISP PRESSADEU 240 The value of the resistor is displayed on PRUSE the 3478A display i
130. th Local Lockout set the only way to return to front panel control is to either turn power off and then on again or execute the Clear Lockout Set Local CL SL message For many controllers this is the same as the LOCAL command i e LOCAL 7 The command LOCAL 7 takes all instruments out of Local Lockout that are on that bus The command LOCAL 723 would return the 3478A to front panel control but a subsequent REMOTE command or OUT PUT 723 would return it to LOCAL LOCKOUT Examnie LOCAL LOCKOUT 7 Comments The LOCAL LOCKOUT message locks out the 34784A s front panel keys including the LOCAL and SRQ keys The lockout will remain in effect until it is cleared over the interface bus by sending the LOCAL message to the multimeter or cycling the 3478A s power 44 REMOTE Examples REMOTE 7 REMOTE 723 Comments The REMOTE command is used to enable the 3478A to switch from local front panel control to remote program control The 3478A must actually be addressed before it will go into its Remote state The Remote state for the 3478A means that the front panel keyboard except the LOCAL and SRQ keys is disabled The REM annunciator in the display is turned on The 3478A remains in the same state after it receives the REMOTE command that it was in before receiving it To disable the LOCAL and SRQ keys use the LOCAL LOCKOUT command You will seldom find it necessary to execute the REMOTE command The REMOTE message is independent
131. tion DC Volts function AC Volts function 2 wire ohms function 4 wire ohms function DC Current function AC Current function Extended ohms function 30mV DC range 300mV AC or DC range or the 300mA AC or DC range 3V AC or DC range or 3A AC or DC range 30V AC or DC range or the 30 ohm range 300V DC or AC range or the 300 ohm range 3K ohm range 30K ohm range 300K ohm range 3M ohm range 30M ohm range Selects Autorange An invalid range for a given function defaults to the most sensitive range if the range specified is too low or the least sensitive range if the specified range is too high Display Selects the 3 1 2 digit display Fastest reading but little noise rejection 1 Power Line Cycle integration Selects the 4 1 2 digit display 1 PLC integration Selects the 5 1 2 digit display Best resolution and greatest noise rejection 10 PLC integration Trigger Internal trigger External trigger Any reading in progress is aborted and the 3478A waits for an external trigger pulse to occur Triggering occurs on the negative going edge of the pulse Readings may also be initiated by an HP IB GET command Single Trigger This causes a single measurement to commence Further readings may be initiated by an HP 1B GET command but not an external trigger pulse Trigger Hold Any reading in progress is aborted and the 3478A remains idle The 3478A will still respond to an HP IB GET command but not to an external trigger Fast Trig
132. ts For any assistance contact your nearest Hewlett Packard Sales and Service Of fice Addresses are provided in the back of this manual How to Obtain Repair Service Most hp service offices in the United States are NOT authorized to service and repair 3478A DMM s Contact your local hp sales office for specific information on where to send the instru ment for repair This will substantially reduce turn around time You may have your 3478A repaired by Hewlett Packard anytime it needs service whether it is under warranty or not There is a charge for repairs after the one year warranty period A list of sales offices is conveniently provided in the back of this manual Outside of the United States repair service may be obtained at your local hp service center Serial Number Each 3478A multimeter carries its own serial number on a plate on the rear panel It is recommended that owners keep a separate record of this number Should your unit be lost or stolen the complete serial number is often necessary for trac ing and recovery as well as any insurance claims General Shipping Instructions Should you ever need to ship your 3478A be sure it is packaged in a protective package use the original shipping container and cushioning material to avoid in transit damage Such damage is not covered by the warranty Hewlett Packard suggests that you always insure shipments Attach a tag to the instrument identi fying the owner and indi
133. twelve messages and are called Bus messages a Data The actual information binary bytes sent by a talker to one or more listener The information data can either be in numeric form or a character string b Trigger The Trigger message causes the listening device or devices to per form a device dependent action when addressed c Clear The Clear message causes the listening device s or all the devices on the HP IB to return to their predefined device dependent state d Remote This message causes the listening device s to switch from local front panel control to remote program control when addressed to listen e Local This message clears the REMOTE message from the listening device s and returns the device s to local front panel control f Local Lockout This message prevents a device operator from manually in hibiting remote program control g Clear Lockout and Set Local With this message all devices are removed from the local lockout mode and revert to local The remote message is also cleared for all devices h Require Service A device can send this message at any time to signify the device needs some type of interaction with the controller This message is cleared by the device s STATUS BYTE message if the device no longer requires service 86 i Status Byte A byte that represents the current status of a single device on the HP IB One bit indicates whether the device sent the require sevice message and th
134. ty CO No controller capability 87 HP IB Worksheet The HP IB worksheet Table A 2 can be used to determine the HP IB capabilities of the other HP IB compatible instruments in a system The sheet may be filled in with the bus message applicability for your controller and for each HP IB device The bus capability for the 3478A has already been filled in Refer to your con troller manual and the manual s of your other device s for their Bus Message capabilities Once the sheet is filed out you should then have the HP IB capabilities of your device s Table A 2 HP IB Worksheet Message Device INSTRUMENT MODEL MODEL IDENTIFICATION 3478A LISTEN AND VES LISTEN TALK HP IB XES ADDRESS 5 BIT VALUE 23 TRIGGER T ET ere CLEAR E DENTEN LOCAL EI Ies A REMOTE CS A HE ee LOCAL R LOCKOUT CLEAR LO amp R SET LOCKOUT REQUIRE S SERVICE STATUS S BYTE STATUS BIT kb PASS N CONTROL ABORT N S SEND ONLY R RECEIVE ONLY S amp R SEND AND RECEIVE N NOT IMPLEMENTED 88 Bus Message Implementation The following eleven figures provide a description of the implementation of the Bus Messages using the 3478A The codes used in the figures are F False T True oct Octal Code X Don t Care Trigger Message from Controller to Device s Data Message Controller to 3478A To send Data from the controller t to the 3478A first T
135. ure 4 1 Power Cahles Grounding Requirements To minimize shock hazard the instrument chassis and cabinet must be connected to an electrical ground The instrument is equipped with a three conductor ac power cable The power cable must either be plugged into an approved three contact electrical outlet or used with a three contact to two contact adapter with the grounding wire green firmly connected to an electrical ground safety ground at the power outlet The power jack and mating plug of the supplied power cable meet International Electrotechnical Commission IEC safety standards 65 Safety Considerations General safety precautions must be adhered to during all phases of operation of the 34784 Failure to comply with these precautions or with specific warnings elsewhere in this manual violates safety standards of design manufacture and in tended use of the instrument Hewlett Packard company assumes no liability for the customer s failure to comply with these requirements This is a Safety Class 1 instrument Operating personnel must not remove instrument covers Component replacement must be made by qualified maintenance personnel Do not operate the instrument in the presence of flammable gases or fumes Operation of any electrical instru ment in such an environment constitutes a definite safety hazard Warnings or cautions precede any potentially dangerous procedures throughout this manual Instructions contained in the wa
136. ver with autozero on a zero measurement is made to null any errors in the A D converter Turning autozero off has the same effect as on dc volts and current Resistance Measurements For 2 wire ohms measurements the autozero feature performs just as it does for DC voltage measurements Resistance measurements using the 4 wire mode re quire different considerations The zero measurement is normally made with the input amplifier shorted to circuit ground In the 4 Wire ohms mode the input amplifier is shorted to the 4 Wire SENSE LO terminal for the zero measurement With autozero ON the zero reading is updated for each measurement cycle With autozero OFF the reading is not updated and may cause an ohms measurement error if the resistance of the test leads change To prevent this error a new zero reading should be taken by changing or updating the state of the 3478A anytime test leads are changed See Also Display Integration Time and Optimizing Reading Rates DE KG MEC Ce HP IB 4 Commands SYSTEMS ZO Turns autozero off Z1 Turns autozero on CALIBRATE What is Electronic Calibration One of the many features of the 3478A is electronic calibration This represents a totally new concept in Hewlett Packard voltmeters Before voltmeters had to be removed from their mounting have their covers removed and mechanical ad justments made Then the voltmeter had to be reassembled and installed But now calibration may be d
137. ware error occurs the controller would be inter rupted 5 Syntax Error If the controller sent an invalid instruction the 3478A would interupt the controller 6 Data Ready The 3478A would interrupt the controller after each completed measurement How to use SRQ When the Require Service message SRQ is sent the computer must determine first which instrument is requesting service This is done by conducting a SERIAL POLL SPOLL of every device on the bus which is capable of requesting service When an instrument is polled it responds by sending a STATUS BYTE which indicates whether it requested service and if so the nature of the request If the Status Byte for the instrument polled indicates that it was not requesting service the computer would continue to poll the other instruments on the bus until the proper one is located This of course assumes that the controller has been pro grammed to respond to the SRQ interrupt 46 Status Register and Status Byte The status register is used to monitor the six possible interrupt conditions It is possible for one or more bits of the status register to be true without the 3478A causing an interrupt The interrupt will only occur when the SRO mask has been set for particular conditions Refer to Figure 3 3 If the SRQ mask is set for certain conditions and one or more of those conditions occur bit 6 of the status register will go true true being a 1 the SRQ annunciator in the
138. which are given in an enhanced BASIC Beginners All purpose Sym bolic Instruction Code programming language such as the Hewlett Packard Model hp 85 uses Trying Out a Command Before we actually begin the programming discussion let s look at a simple exam ple that displays your name on the 3478A display If you have one of the con trollers shown below type in the commands as shown Even if you don t have one of the controllers listed read through this section anyway as it provides a basis for later discussions Enter the command exactly as shown using your own name capital letters in place of your name Computer Type The Message Press hp 9825 wrt 723 D2your name EXECUTE hp 9835 9845 85 OUTPUT 723 D2your name EXECUTE on the hp 85 D PRESS END LINE 35 Actually any message of up to 12 characters may be displayed in this manner The command D2your name tells the 3478A to display the message your name in its display D2 is called the COMMAND CODE The 3478A cannot display lowercase letters it displays unusual symbols instead It can display however special characters such as 96 amp etc Try these characters in place of your name At the end of this chapter are several blue pages that describes each of the pro gram commands the 34784 will respond to and how they are used As an added plus at the back of the manual is a Command Quick Refe
139. y 2 seconds regardless of how long the Self Test button is depressed Simplified Operation The front panel of the 3478A is designed for ease of use by logically grouping keys that are functionally related This chapter is in tended to provide a basic working knowledge 3478A in making typical measurements Measurement Function Keys Use the first six keys along the top row to select the type of measurement you want to make CN DC Voltage V AC Voltage DC Current AC Current A 2 WIRE 2 Wire Ohms 4 WIRE 4 Wire Ohms Ka a VE Numb of Digits D played The SHIFTED functions of the range keys are used to select alternate numbers of display digits This feature is provided as a means to increase reading rates but with a trade off of noise rejection and resolution Be sure to read DISPLAY and OP TIMIZING READING RATES in Chapter Il 3 3 1 2 digit mode AUTO fastest reading rate MAN least resolution and lit tle noise rejection 4 Pai 4 1 2 digit mode 5 5 1 2 digit mode best noise rejection slowest reading rate luccm Display 12 character alphanumeric displav with 12 dedicated annunciators The display is read directly in engineering units i e MV for milli volts MOHM for Meg ohm resistance etc X X K am ON MOFF LINE RANGE BOOB P a 7 PA Range Keys The range keys as the name im plies are used to select the pro pe

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