Keithley 487, 486 Service manual

WARRANTY

Keithley Instruments, Inc. warrants this product to be free from defects in material and workmanship for a period of 1 year from date of shipment.

Keithley Instruments, Inc. warrants the following items for 90 days from the date of shipment: probes, cables, rechargeable batteries, diskettes, and documentation.

During the warranty period, we will, at our option, either repair or replace any product that prows to be defective,

To exercise this wammty, write or call your local Keithley representative, or contact Keithley headquarters in Cleveland, Ohio. You will be given prompt assistance and return instructions. Send the product, transportation prepaid, to the indicated service facility. Repairs will be made and the product returned, transportation prepaid. Repaired or replaced products are warranted for the balance of the original warranty period, OT at least 90 days.

LIMITATION OF WARRANTY

This warranty does not apply to defects resulting from product modification without Keithley’s express written consent, or misuse of any product or part. This warranty also does not apply to fuses, software, non-rechargeable batteries, damage from battery leakage, 01 problems arising from normal we.a~ or failure to follow instructions.

THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. THE REMEDIES PROVIDED HEREIN ARE BUYER’S SOLE AND EXCLUSIVE REMEDIES.

NEITHER KBITHLEY INSTRUMENTS, INC. NOR ANY OF ITS EMPLOYEES SHALL BE LIABLE FOR ANY DIRECT, INDIRECT, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF ITS INSTRUMENTS AND SOFTWARE EVEN IF KEITHLEY INSTRUMENTS, INC., HAS BEEN ADVISED IN ADVANCE OF THE POSSIBILITY OF SUCH DAMAGES. SUCH EXCLUDED DAMAGES SHALL INCLUDE, BUT ARE NOT LIMITED TO: COSTS OF REMOVAL AND INSTALLATION, LOSSES SUSTAINED AS THE RESULT OF INJURY TO ANY PERSON, OR DAMAGE TO PROPERTY.

Keithley Instruments, Inc. - 28775 Aurora R

Model 486 Picoammeter

Model 487 Picoammeter/Vokage Source

Instruction Manual

01990, Keithley Instruments, Inc.

Cleveland, Ohio, U.S.A.

Fourth Printing, August 2000

Document Number: 486-901-01 Rev. D

Manual Print History

The print history shown below lists the printing dates of all Revisions and Addenda created for this manual. The Revision Level letter increases alphabetically as the manual undergoes subsequent updates. Addenda, which are released between Revisions, contain important change information that the user should incorporate immediately into the manual. Addenda are numbered sequentially. When a new Revision is created, all Addenda associated with the previous Revision of the manual arc incorporated into the new Revision of the manual. Each new Revision includes a revised copy of this print history page.

Revision C (Document Number 486-901-01) Revision D (Document Number 486-901-01).

............................................. December

................................................. August 2000

1991

BESCHEJNIGUNG DES HERSTELLERS/IMl’ORTEURS

Hiermitwirdbescheinigt,(daS)/dasMODEL 486 PICOAMMETER AND MODEL 487 PICOAMMETER/ VOLTAGE SOURCEinUbereinstimmungmitdenBestimmungenderVfg1046/1984funksntstortist.DerDeuk~en

Bundespost Eiihmg der Bestimmungen eingeraumt.

Die Einhaltung der betreffenden Bestimmungen setzt vordus, dag, (da& geschirmte Mt$leitungen venvendet werden. Fur die Beschaffung richtiger Me~leitungen ist der Betreiber verantwortlich.

DIESES GERAET WURDE SOWOHL ElNZELN ALS AUCH IN ElNERANLAGE, DIE EINEN NORMALW ANWENDUNGSFALL NACHBILDET, AUF DIE EINHALTUNG DER FEN

GEPRUEFT. EST IS JEDOCH MOEGLICH, DASS DIE UNGUENSTIGEN UMSTAENDEN BEI ANDEREN G ERAETEKOMBJNATIONEN NIGHT EINGEHALTEN WERDEN. FUER DIE EINHALTIJNG DER FUNK-ENTSTOERBE GEN SEINER GESAMTEN ANLAGE, IN DER DlESES GERAET BETRIEBEN WlRD, IST DER B?ZlXEZBER VERANTWORTLICH.

wurde

das Inverkehrbringen dieses Gerates angezeigt und die Berechtigmg ZUI Uberprufmg der Serie auf

FUNK-ENTSTOEXB -GEN IJNTFX

Keithley Instruments, Incorporated

CERTIFICATE BY MANUFACTURER/TMPORTER

ThisistocertlfythattheheMODEL

SOURCE isshielded againstadiointerferenceinaccordancewiththeprovisions ofVfglO46/1984. TheGermanPostal Services have been advised that this device is being put on the market and that they have been given the right to inspect the series for compliance with the regulations.

Compliance with applicable regulations depends on the use of shielded cables. It is the user who is responsible for prycuring the appropriate cables.

THIS EQUlFMENT HAS BEEN TFSTED CONCERNING COMPLIANCE WITH THE RELFVANT RFl PROTECTION REQUIREMENTS BOTH lNDMDUALLY AND ON SYSTEM LEVEL (TO TION CONDlTIONS). HOWEVER, IT IS POSSIBLE THAT THESE RFI RBQCERTAIN UNFAV0RABL.E CONDlTIONS IN OTHER INSTALLATIONS. lT IS THE USER WHO IS RESPONSIBLE FOR COMX’LIAN

CE OF HIS PARTICULAR INSTALLATION.

SIMULATE NORMAL OPERA-

ARENOTMETUNJXR

Keithley Instruments, Incorporated

Safety Precautions

The following safety precautions should be observed before using this product and soy associated instrumentation. Although some inmument~ and accessories would normally be used with non-hazardous voltages, there are situations where hazardous conditions may he present.

This product is intended for use by qualified personnel who recognize shock hazards and am familiar with the safety precautions mquired to avoid possible injury. Read the operating information carefully before using the product.

The types of product users are Responsible body is the individual or group responsible for the use

and maintenance of equipment, for ensuring that the equipment is operated within its specifications and operating limits, and for ensuring that operators are adequately trained.

Operators use the product for its intended function. They most be trained in electrical safety procedures and proper use of the instmment. They most be protected from electric shock and contact with hazardous live circuits.

Maintenance personnel perform routine procedures on the product to keep it operating, for example, setting the line voltage or replacing consumable materials. Maintenance procedures are described in the manual. The procedures explicitly state if the operator may perform them. Otherwise, they should be performed only by service persomlel.

Service personnel are trained to work on live circuits, and perform safe installations and repairs of products. Only properly trained service personnel may perform installation and service procedures.

Users of this product most be protected from electric shock at all times. The responsible body must ensure that users are prevented access and/or insulated from every connection point. Io some cases, connections must be exposed to potential human contact. Product users in these circumstances most be trained to protect themselves from the risk of electric shock. If the circuit is capable of operating at or above 1000 volts, no conductive part of the circuit may be exposed.

As described in the International Electrotcchnical Commission (IEC) Standard IEC 664, digital multimeter measuring circuits (e.g., Keitbley Models I75A. 199, 2000,2001,2W2, and 2010) are Installation Category II. All other instruments signal terminals are Installation Category I and most not be connected to mains.

Do not connect switching cards directly to unlimited power circuits. They are intended to be used with impedance limited sources. NEVER connect switching cards directly to AC mains. When connecting sources to switching cards, install protective devices to lim-

it fault cwrent and voltage to the card.

Before operating an instrument, make sore the line cord is connectcd to a properly grounded power receptacle. Inspect the connecting cables, test leads, and jumpers for possible wear, cracks, or breaks before each we.

For maximom safety, do not touch the product, test cables, or any other instruments while power is applied to tic circuit under test.

ALWAYS remove power from the entire test system and discharge

any capacitors before: connecting or disconnecting cables or jompen, installing or removing switching cards, or making internal changes, such as installing or removing jumpers.

Exercise extreme caution when a shock hazard is present. Lethal voltage may he present an cable connector jacks or test fixtures. The American National Standards Institote (ANSI) states that a shock hazard exists when voltage levels greater than 3OV RMS, 42.4V peak, or 60VDC are present. A good safety practice is to expect that hazardous voltage is present in any unknown circuit before measuring.

Do not touch any object that could provide a cormot path to the common side of the circuit under test or power line (earth) ground.

Always make measurements with dry hands while standing on a

dry, insulated surface capable of withstanding the voltage being measured.

The instrument and accessories must be used in accordance with its

specifications and operating instructions or the safety of the equip-

ment may be impaired.

The WARNING heading in a manual explains dangers that might result in personal injury or death. Always read the associated information very carefully before performing the indicated procedure.

Do not exceed the maximum signal levels of the instruments and accessories, as defined in the specifications and operating infonna-

don, and es shown on the instrument or test fixture panels, or switching card.

When fuses are used in a product, replace with same type and rating

for continued protection against tire hazard. Chassis connections must only be used as shield connections for

measuring circuits, NOT as safety earth ground connections.

If you are using a test fixture, keep the lid closed while power is applied to the device under test. Safe operation requires the use of a lid interlock.

Ifa@ screw is present, connect it to safety earth ground using the wire recommended in the user documentation.

Then fer to the operating instructions located in the manual.

-Ibe A sure 1000 volts or more, including the combined effect of normal

and common mode voltages. Use standard safety precautions to

avoid personal contact with these voltages.

symbol on an instmment indicates that the user should E-

symbol on an instrument shows that it can source or mea-

The CAUTION heading in a manual explains hazards that could damage the instrument. Such damage may invalidate the warranty.

Instrumentation and accessories shall not be connected to humans. Before performing any maintenance, disconnect the line cord and

all test cables. To maintain protection from electric shock end tire, replacement

components in mains circuits, including the power transformer, test leads, and input jacks, must be purchased from Keithley Instnmenu. Standard fuses, with applicable national safety approvals, may be used if the rating and type are the same. Other components that are not safety related may be purchased from other suppliers as long as they are equivalent to the original component. (Note that se-

lected parts should be purchased only through Keithley Insrmments

to maintain accuracy and functionality of the product.) If you are

unsure about the applicability of a replacement component, call a Keithley Instruments office for information.

To clean an instrument, use a damp cloth or mild, water based

cleaner. Clean the exterior of the instmment only. Do not apply cleaner directly to the instrument or allow liquids to enter or spill on the instrument. Products that consist of a circuit board with no case or chassis (e.g., data acquisition board for installation into a computer) should never require cleaning if handled according to instructions. If the board becomes contaminated and operation is affected, the board should he returned to the factmy for proper cleaning/servicing.

Rev. IO/99

SAFETY WARNINGS

hstmnentation and accessories should not be connected to humans.

The following prec.~tions should be observed before using Model 4&X/487. Refer to main manual for detailed safety information and complete operating instructions.

The Model 486/487 is intended for use by qualified personnel who recognize shock hazards snd are familiar with the safety precautions required to avoid possible injury. Read over the instruction manual carefully before using the ins+nunent.

Before operating the instrument, make sore the line cord is connected to a properly grounded power receptacle.

Exercise extreme caution when a shock hazard is present. Lethal voltages may be present on the test fixture or the Model 487 output jacks. The American National Standards Institute WNSI) states that a shock hazard exists when voltage levels greater than 30V RMS or 424V peak are present. A good safety practice is to expect that hazardo~voltageispresentinany~o~cirmitbefore measuriug.

Inspect the connecting cables, test leads, and jumpers for possible wear, cracks, or breaks before each use.

Maintenance should only be performed by qualified service personnel. Before performing any maintenance, disconnect the line cord and all test cables from the instrument.

CONTROL SUMMARY

DISPLAY INTENSl7Y: Selects normal/dim/off display.

LOCAL: Places unit in local and restores front panel key opergion.

MENU: Use with the knob or cursor keys to configure the

following menu items; data store, data recall, I-limit (Model487), integration, IEEE-488 bus Coos or talk-only), defaults, self&t, debug, calibrate, and V-Source calibrate (Model 487 only).

SHIFT EXIT:

ZERO CHECK Allows check of offsets, and must be disabled to obtain an input signal measurement.

SHIFT CORRECT: Performs automatic zero correction to null insment offsets.

FILTER: Enables or disables the selected filter(s).

&ik MENLJ or trigger SETUP.

Formadmumsafety,donot touchtheModel487connections, teat fixture, test cables or connections to any other instruments while power is applied to the circuit under test. Turn off all power and discharge all capacitors before connecting or disconnecdng cables or jumpas. Also, keep the test fixture lid dosed while power is applied to the device under test. Safe operation requires the use of the lid interlock.

Do not touch any object which could provide a current path to the common side of the &cuit under test or power line (earth) ground.

Do not exceed the maximum signal levels of the in&ument, as shown on the rear panel and as defined in the specifications and operation section of the instnxtion manual.

Connect the - screw of the test fixture to safety earth ground using #I8 AWG or larger wire.

SHIFTFILTER SELECT: Use with knob or cursor to select the f&r(s); digital, analog, or digital + analog.

REL Use to establish a baseline using the displayedreading.

V RANGE A: Use range keys to select a lower or higher

current range. SHm AUTO RANGE: Use to enable/disable autorange. SETLIP: Use with knob or cursor keys to con@ure the fol-

lowingtriggersetupitems;triggermode,triggerinterval, trigger delay, and bigger source.

OPERATE: Places V-Source of Model 487 in operate or standby.

TRIGGEE Press to trigger a reading or start the data store.

PRESET: Toggles between two preset V-Source values

(Model 487 only).

SHIFT OHMS cV/Ij: Press to select V/I Ohms.

TYPICAL CONNECTIONS

(Model 487 shown connected to Model 8CKQA test fixture)

Model 8002A

- 487

“-so”rcw

Equivalent circuit

LO 487

Plcoammeter

CONSIGhTS DE SECURITF!

RESUME DES COMMANDES

n faut prendre les pr&autions suivames avant d’wiliw les me d&les 4861487. Veuilk vow reporter au manuel principal qui comiem tous les remeignemenu sur les consigns de skcuritt

ainsi qw les clirectiva d’utilisation. LE mod&s 4861487 soot destiks a des spkialistes cotxcients

des dangers de secow &cuique et co-t les mesur-es de prkntion g prendre pour eviter tout risque de blesnuex. Veuilez lire attentivemeot ce manxl avant d’utiliser l’insmtment.

V&&z., avant d’utiliser I’instmment, que le cordon soit branchC SW une prise convenablement reli& B la term.

Redoublez de pr&autions lorsqu’il existe tm risque de secow &cttique. Des tenkn.5 moxtelks risqueot d’&.e pksentes au n&au du circuit d’essais ou des j&s de sortie du mcckle 487. selon l’instintt amticain des normes (ANSI), il e&e ml risque de secousse &cuique lorsque le nivem de la tension d+asse 30 V efficaces ou 42,4 VC de tension c&e. If esf toujours prudent de consid&r.er qu’une tension dangerewe est prknte dam tout circuit incomm avant dkffectua une mesure.

Examinez l’itat da cslbles de cotmexion, des fils d’& et des cavaliers pour s’asurer qu’ils ne prksentent ni &g&B d’usure, ni aaqlxlures, ni fissures want chaqlle essai.

Pour un maximum de s&m-it& ne touchez pas les fik du mod&

487,

le circuit de mesure, les &les d’essais, ni les braochemenn a attam mm inmument lotxque le circuit en mm-s d’essai est at.5 tension. Coupe2 l’alimentation en comam et d&barge2 tous les con~teun avant de braocher ou de &brancber d-es c5ble-s. ll faut +akment veiller A ce que le couvercle du circuit de mesure d’mais mte fermi pendant que l’appareil en cow-s d’essai est sous tension. Le vermuillage du couvercle et nkssaire pour tm foIutiomlemem en tome skmi~.

Ne touchez aucun objet susceptible de fomnir tm chemin conductem vers le c&k commun du tit en cows d’essai ou la terre (masse) &I circuit d’alimeotxion.

Ne .L+SS.Z pa 1s nivemx malt 6gurant sur le pamleau an&e et d&is a” chapitre caratt&istiques et folxxionnement de la notice d’utilisatiotl.

Fiiezlavis Q dudrruitd’eyaisalaterregl’aided’un~de jauge 18 AWG ou plus gms.

lnsrmmena et accgsoiTes somles

lo ne faut faire edcuter la maintenance que par du penonnel Spe cialisd. Dkbranchez le cordon d’alimentation et tous les Cgbler d’esais de I’instmment avant d’effecmer tme quelconque o@ra don de maintenance.

maximum de sigoaux de l’iosav

ne dokent pas be oxcord& g des per-

lNZBX!SIl?E D’AFHCHAGE (DISPLAY lNTEN.SITyI :

Pennet de s&ctiomw : normaL&.ible!pas d’affichage.

COMMANDE DIRECZZ (LOCAL) :

r-em l’appareil et remet en foxtionnement les touches du panneau d’affichage.

MENU (MENU) : s’udise avec le bouton on les touches du NTsew pour configurer Ia &mems suivants du menu : mise en m&mire de dam&, rappel de doonkes, limite I (tooMe 487), int&mion, le bus EEE-488 (voie de tmmmksion ou communication seulement), v&m par d4fam, contrble automatique, mise au point, balormage et &lomage de la source de tension V (mod&

487 seulement).

TOUCHE MAJUSCUJX - SORllE (SHIFTEXI’IJ :

de soti du MENU oli de d&lencher I’INSTALLATION @ETup).

lrwFCATIoN DU ZERO (ZERO CHECK) :

ficatim cles d4cdam et doit &re invalid& pour obtenir le signal normal de sortie.

Permet de commander di-

Permet

Pet-met la v&i-

TOUCHI? MAJUSCULE - CORRECTION (SHlFT COR-

RECTJ : R&l&e la mix e z&o automatique pour am-&r les c2kcalaga des instruments.

TOUCHF MAJUSCULE - SELECTION DU FLXRE

(SHIFT FILTER SELECT) : s’urilise avec le bouton ou le curseu pour selectiotmer le(s) filtfe(s); mm&iqtx, analogique 0” numkique + analogique.

V RANGE A (RANGE) :

selectiomler lme gamme plus basse ou plus haute.

Utilkez les touches de gamme pcnu

TOUCHE MAJ(ISCULE - GAMME AUTOMAnQUE

(SHIFi- AUTO RANGE) : s’wilis pour valider ou irmlickr

mode gamme automatique.

IhSTALLATION (SETUP) : s’unlise avec un bouton ou les

touches c,mems pour configurer le ciichchmat des systemes de cklenchemem suivaoa : mode &clenchement, intervalle de Wenchement, retard de dklencbemem et source de dkclencbe *em.

FONCli’ONNEMtWT (OPERA=) : Met la source

V du ma&k 487 en fonaioonement ou en veik.

DECLWCI.zW@h’T (TRIGGER) :

tme lecture ou d&arer la mix en memoire des doom&.

PREREGLAGE (PRESEV :

sources de t&on V (mod& 487 seulement).

Pa-met de ba.scuk entre V&LIE de

Appuyez pour d-klmcber

de tension

TOUCHE MAJUSCULE - OHMS (SHI3T OHMS V@ :

puyez pour sactiomler v/l ohms.

SCHEMA TYPE DE BRANCHFNENT (Mcd+.le 487 mom& branch& P Ia charge d’csai 8002A)

Cimit dquivalent

DUT

SICHERHEITSHINWEISE

KONTROLLBEGRIFF’E

Vor dem Gebrauch des M&ells 4861487 soIlten Sie folgende Vorkehrungen &fen. Wenden Sie sich hinsichtlich ausfiihrlither Sicherheitsinformationen und vollst&~diger Bedienungsm weisungen an das Haupthandbucb.

Dar M&U 4861487 is fiir den Gebrauch durch qu&izierts Personal ausgelegt, das eine Stromwhkggefahr erkenm und mit da Sicherheitworkehmngehrungen vertraut ist, die zur Verhinderung einer mbglicben Verletzung pea&n we&n miisxn Vor den G&much des G&&s sollten Sie da Anweisungshandbuch sorgfag lesen.

Vor Uxtriebnabme des G&es soilten Sic da-auf achten, da& da Suomkabel mit einer vo~ig gee&ten Suomquelk verbunden is.

S&e Suomvhlaggefabr best&n, so g&en Sie mit Xuiulsenter Vosicbt var. Auf der Tatvonichtung c&r den Amcbliisxn des Modells 487 kijnnen t&&he Sparmungen vorhanden sein. Das American National Standard Institute (ANSQ weist damuf bin, da& eine Suomschlagg~ dam besteht, wenn die SFannungswene h6her als 30 Volt RMS oder 42,4 Volt Spia&is@.mg be uagen. Eine gute Sicherhei@nahme ist die Vermutnng, da& in jedem unbekannten Stromkreis vor dem MS sen eine g&liche Spamung vorhanden is.

PrJfen Sie vor jeder

Briicken auf m&$icbe Abnutnmg, Rise cder Briiche.

Beriibren Sie LUT maxim&n Siiherheit keine Amcbiiisse, Priifvonichtungen, Priifkabel ode Verbindungen zu anderen Ge men, w&rend der zu priifende S~omkreis mit Strom versorgt wird. Sellen Sic den Strom ab und entladen Sic alle Kondensatmen, bevor Sic K&l c&r Briicken an&Ii&n oder trennen. H&en Sic auBer&m den Testmscbl&deckel ggchlos~en, withrend das zu priifende G&t mit Strom versorgr wird. Eine sichere Bedhung bedeutet die Benutzung e&s Deckeischlosses.

Baiihrm Sie keinen Gegastan& der eine Stmmleitung LUT ge meinsamen site des zll priifendsI stmmkreises cder deI Stromkatebnaw dare&.

iiberschreiten Sic nicht die auf da Riickseite des G&&es verge gebenen HlichstwMe, die auBer&m ix-n Kapitel Tech&&e Dawn und Beuieb da Bediemmgshandbuchs bschrieba sind.

V&inda Sie die 0 = Scbraube des Pr&xchl- mit Hilfe eims Nr. 18 AWG c&r gr&ren Kabels mit da Masse.

Geme und Zubehtir s&a nicbt an Mahen an&+scblassen werden.

Die Wammg s&e nut durch qualifiziertes Penxnl vorgenommen werden. Vor einer Wammg des Get-&s solken das Stromk&l und alle anderen Priifkabel van diem geuennt werden.

BmuQung

alle Verbindungskabel, Priif?abel

AN.ZIGEHELLIGKEIT (DISPLAY Ihfl.ENSI~):

Anzeige normaUabgedunkeltiaus.

LOKAL (LOCAL):

Frontabdeckungstastenfunkdon wieder her.

Genii (MENlJ: Venvenden Sie diesen B&hl nsammen x-nit den Knopf- c&r C~rtasten, um f&en& Meniidaten abzur&n: $&hem der Dawn (data store), Abmfen der Data (data red), IGrenrwert (Rimit) (Mcddl 487), Integlatioxl (mtegradon), IEEE-488 VielfKhlenmg (nur Vielfachleitung a.& Gqdch), Nullstellungen (~dts), Sehtpriifung (seXtest), Emstijren (debug), Eicben (calibrate) und Spannungs4u~~tichu,-,g (V-Sowc~ calibrate) (nw MC&II 487).

SHIFT EXIT (SHIFT EXIZJ: Bender, ME& c&r auslijsen SETUP.

NULL?‘RiiFUNG (ZERO Ch!ECK):

Abweicbungen und mui3 zum Erhaltm einer F.ingabesig-

nabnaung unterbrwhen we&a. SHFi- CORRECT (SHLFT CORRECT Fiibrt automatische

Nullkorrektur ZUT Nulhllmg der Ger&abwichungen durcb. FZLTER (RZERJ: Bet&&t oder unterbricht da?&& gewiihlte(n)

Filter.

Bringt Geriit in Local-Modus und stellt

Em@licbt Priifung der

Wtit

SHIFi-FLLTER WAHL (.SHL=TRLll?R SELECn: Venvenden

SiediesenBefeblr ter zu bestimmm; digital, analog cder digital und analog.

REL (R.&C): Verwada Sie diezen Befehl, urn linen Gnmthvert

fiir die angezeigte Ablesung faulegen.

V BJZREICH A (RAh’GE):

urn e&n nkdrigeren oder h&eren Strombereicb festzulegen.

SHIFT AUTO-BEREICH (SHIFT AUTO RANGE):

den Sie diesen B&l, um den AutoBaeicb (autorange) Befehl zu aktividd.

AUIT7ELLVNG (SEW): Verwenden Sie diesen Befehl zusammen mit den Knopf- odet Curscnasten zur Kon&uration folgender TrQeritnp~ufsteUun~; Trig&mndus, TriggerintervaIl, Tti~emerr6genmg und TriggerqueUe.

BETRlEE(OPERATE):

487 in Be&b c&r Standbymcdu.

TRIGGER (ZWGGER): Betitip Sic dige Taste, urn eine Ab lesung cder die speichaung “on Lktm awdiisen.

usammen nit Kxpf c&r Cunor, urn die Fil-

Benutzen Sie diese Bereichsmsen,

Verwen-

Bringt Spannungsquelle de Mcdells

VORGABE (PREFl-: Schdtet zwischm zwti vor~e&enen

Spannm~uellenwerten (mu Modell487).

SHIFT OHM (V/I) (SHIFT OHMS V7Ij:

Taste, urn V/I Ohm zu betimmen.

Driicken Sie dies=

GEBRiiUCHLICHE ANSCHLijSSE (Abbildq zeigt McdeU 487 an Priifgeriit Mcdell8002A “I@chlossen)

NORME DI SICUREZZA

IUASSUh’TO DJ3 COMANDI

Le name di sicurezza segwnd dew10 mere mervate prima di ware U modello 4861487. Fate riftiento al rnmuaie principale per “ngsioti demgu suue norme di sicurn e le is”lKio”i per I’uro.

II modello 4861487 e’ stat0 progetrato ad uo di pe~nale qlmlificato, a co”cscenza CM Ii&i0 di sccma elemica ed awnte

-ma’ co” le preca”z.ioti necemarie per evimre ogni da”“0 possibiie a persane e case. Leggem attentamente quest0 “ranwale prima di udliuare lo sml”lento.

Prima di far fu”zionare lo sml”lento, &%sic”ratevi the il cordone elemico sia appmmamente adlegato ad una press di alimentazione CO” la mesa a terra ccuretm.

Prrstate esn-ema atten7io”e in situazioni in cui e’ prwnte il rischio di sccaa elletrica sulk3 -ento 0 “el cimdto di prow% in qtmnto e’ p&bile the vi si rilevino tensioni considerate letah imprerse dall’utente. L‘ANSI (American National Standard Insti~te)riconmceurischiodismssaelemicdinpresenraditensioni di picco ma&xi di 30V RSM o 42.4V. E’ buona “orma coti* presenti tensio”i peric&se i” ogni circllito elemico slxmxiuto.

Controllate i cavi di mnnesSone ed i conmti prima delYw per witare problemi cwati da usurq crepe o romue.

Per maggior sicurezza, “on toccate il cirtito ed i cavi di prova, 0 II” qualsiasi ah smlme”t0 una volm applicam -te al cirait0 di prow. Diskwrite I’alimentazione e saricam tutti i condensatori prima di connette~e o sonmetwe i cati. Mante”ete inoh chi”so il cope&h dell’impianto di prow quando si applica corrente au’apparecchio the ti vuole prowre. Per ““‘@Gne sicwa necesrio un copxhio the, se apert”, bloxhi aut0”laticame”te 1 parsaggio di ccrrelte dl’apparecchio.

Non tcccate alcun oggetto the possa ccmvmtire passaggio di COP reme al km conlune dd circuit0 in prwa 0 aIla massa (tara) ala linea d.i tensione.

Non superate l’ingreso di tensione nwsimo, come yxcifiato nell’appmito capitol0 sul hnzio”a”wnto, conten”to in quest0

nmnuale. collegatelavite 1 d.eu’apparecchiaturadiproMa-usan-

do~un avo No.18 AWG o pii~ spgso.

Gli -enti e gli accessori non devono mai - collegati ad esxriumani.

IA “m”uterKio”e dew gsere equita esclusivame”te da perso”& q”alificato. Prima di efkmMre ahn lavoro di “m”“teD ione scollegate u Lea”0 di hea e tuni gu alti cavi di prcwa daIl0 SO-lU”~rO.

INDICA TORE INZWSITA ’ (DISPLAY INllENSIITyI:

Peimette la selezione delh chiareua delhdicatore tra “or“mldchiarol~to.

LOCALE (LOCAL]:

l’opemivim’ del pannell a ati.

MENU (MJZNV): Wene usam aamite la mancpla 0

cursore per scegliere “a: menlorizzazicole dati, richianlo dati, limite di corrente (Modello 487), integrazim, conngsione IEEE-488 (connesione 0 solo speaker), dehllt, test autonmtico, debug, calibratua. e calibrantra sorgente di tasione. (Solo modello 487).

.sHlmExlT (Srnrn~: Exe ti menu e prowxa la IMzlALrzzAz10NE.

Pane il dis@tivo in wo locale e riprki”a

i tarti del

CONTROLLO RLPRIS7liVO (ZERO CHECK): Commte il

mnuoUo degli offset, e deve esere dkinwito per omenere un seg”ale nornmle in lmcim.

CORREZIONE SHIFT (SHIFT CORRECT):

autGmaticar”ente una cotrezio”e di ripristi”0 per a”““llare la telciione di &et dell0 smlme”to.

FEZ?0 (FUTER): Aziona 0 diskeke i flui sekio”ati. sHIFT~oNEmmo (.s%TFILl-ERsElEc1): uwe

la rnmopola 0 U amore per scegliere il f&c(i): di&ale, analo~co, oppure digimle + analogico.

REL @EL): Usato per stabike un punt0 di rihirnento uando i dati “xsuati.

V CAMP0 DI VARlAZIONL? A, (FLANGE): Usate

campdivariadoneperseler&uncampodi-per la corrente piti “as0 0 phi risueno.

Effenua

i tasti del

SHl?i- CAMP0 DI VARIAZIONE AUTOMAlTCO (SIfIFT AUTO RANGE): Usato per aricmareldidnsaire il camp di variazione autmnatico.

-ONE (SE’TW): Usate k nmnopch o i msti del l2umn-e per la ccm6gurazione delle s.eguellti carattetistiche dd in? pulw (nigger); mcdulo trig&a, il-lmrvaJlo, rimrda, e sorgente.

FUNZONAhfENTO (OPERATE):

mea la sorgente di taskme deI MakIlo 487. IMPLLLSO (EQIGGER): Premete imp&o per ottenere ““a let-

ma 0 dare inizio alla mfznmimione dati.

Rmde operadva o mate in

PREsELEnONE (PRESEZJ: sama Isa k due pxizioni COT-

l-i!pnde”ti ai due vd0I-i predetaminati per la sorge”te di tar &me. (Solo M&k 487).

SHIFT OHM (v/l) (Srn OHMS v7: Premete per scegliere lami.uenzai”ohmsvn.

c0NNEss10NI TIPICHE

(E’ n-,nstrato il Mod& 487 connesso al Mod& 8002A come aw&tura di prova)

.__---_-----

Mdek.8W2A

11-w-w

-I”....L

___ _-------

M-m-

-"=-I

zz"

Z3ZZ!kZ

i3iL

_----B-e-----

E=JL 8oOP.A

ADVERTENCIAS DE SEGURIDAD

SUMARIO DE CONTROL

Las precaucione siguientes deben ser observadas arms de war los Modelm 4861487. Remitirse al manual principal para informa&n detdada de xgtuidad e instmccion~ completas de fundonamiento.

Tener cuidado extreme cuando hay la posibilidad de chque elktrim. F’wdem existi voltajes letaks en ks davijas de tida del Mod& 487 6 en el accesorio de prueba. El Ins&to National Ameicmo de Norms (ANSI) expose que e&e un peligro de

chcque cuando bay presents niveks de vohaje de mk de 30V

VCM (valor cuadrhtico media) 0 de 42,4V pica. Una buaa pktica de seguridad es la de espemr que haya voltajes peligmscs presentcs en cdquier circuito desconocido antes de medirlo.

LNTENSIDAD DE PRESENTACION (DLWAY INllW SIm): selffdonar

LOCAL (LOCAL):

OperadLin de la llave de] panel delantero. MENU (MEh’U): Se usa con lar Uaves del cursor o perilla para

mdigum lo siguiente: alma- ‘elm de dates, recuperaci6Il de dam, limite de coniam 0 (Mcdelo 487), integradn, bam IEEE-488 (balm 0 tile voz), surdtuci6n, autqlmeh, ebminacibn de fallas, cezdilmtibn y calibraci6n de fuente de voltaje (V) (sdo

Mod&

preentack% normal/amotigzuh/apa~da. Pane a la unidad en acci6n local y restaura la

487).

CAMBIO SALWA (SHFi-m: S&b del MENU o activa-

citi de Prepara&n (SETUP).

COMPROBACION DE CERO (ZERO CHECK):

compmbacih de desplammientos y dek ser inhabilitado par-a ob

tenermamedici6nde~deenuada.

Permite la

CORFECION DE DEV’LAZAMZW TO (SHIFT COR-

RECT R& correcd6n autcm&ica de cero para balancear de plazaodentos del instnunento.

Fm-Ro (EllTER): Habilita 0 inbabilita el 0 los iiltm s.2k.io rlados.

No war nin@n objeto que pudka provea un camino a la cctieme al Iado comirn &I circuim bajo prueba o la tiena de la line3 de energia.

~GAMAA~GE):UsalasUaverdegamapara~~onar lmgamade conimte mis elm 0 mAs baja.

CAMBIO GAMA AUTOMATICA (SHIFT AUTO RANGE)): Se wa pm bab la gama autodtica.

PREPARACION (SE77lP): Usado cm Uaves de tumor o periua pal-a Nmiigurar la disposiciones sigulenm d-2 activti6n: moda-

lidad de activtibn, imervalo de activaci6n, demaa de activaci6n. fuente de acdvacih.

OPERACION (OPERAlF): Siti k

en Funcionamiu~ta o Espwa.

Fueme V del Modelo 487

AC’i7XACION (TRIGGER): Se deprime para activar una kcturd 0 catlauar al almacenamulto de dam.

PREAJUSZE(P~: OS& emre cim v&n-es de la

preajustados (s5lo Mod& 487).

CAMBIOS OHMIOS v/c (SHIJT OHMS v7q se

sek@ilmal otios Voltaje coniente.

Fueme V

optime para

CONEXIONES TIPICAS

(Mod.90 487 mcsuado conmado a arreylrio de pm& M&lo 8002A)

- .--------.

w-P--

Circuit0 equivatente

SPECIFICATIONS

MAXIMUM READING RATES (readings/second):

VOLTAGE SOURCE (487 only):

IEEE-488 BUS IMPLEMENTATION

contains general information, inclding features, unpack-

ing insimxtions, and a brief description of available acces-

SO&S.

SECTION

General Information

Includes an overview of the front panel and rear panel configuration and basic test procedures. Use this information to getyourMode1486or487up andmmingas quicklyaspossible.

This section contains detailed information on operating the Models 486 and 487 from the front panel.

SECTION 2

Getting Started

SECTION 3

Front Panel Operation

Contains information on using the Models 466 and 487 over the IEEE-488 bus.

SECTION 4

IEEE-488 Reference

Provides the procedures necessary to verify that the Models 486 and 487 are operating within stated specifications.

SECTION 5

Performance Verification

I 1 I

A description of operating principles for the instrument is located in this section. The various analog and digital circuits are explained.

Details maintenance procedures for the Models 486 and 487, including fuse replacement, calibration and troubleshooting.

Includes replacement parts information, schematic diagrams and component location drawings for the Model 486 and 487.

SECTION 6

Theory of Operation

SECTION 7

Maintenance

SECTION 8

Replaceable Parts

SECTION 1

1.1

1.2 FEATURES.

1.3 WARRANTY INFORMATION,

1.4

1.5

1.6

1.7

1.8

SECTION 2

2.1

2.2

2.3

2.3.1

2.3.2

2.4

2.4.1

2.4.2

SECTION

- General Information

INTRODUCTION.

MANUAL ADDENDA SAFETY SYMBOLS and TERMS SPECIFICATIONS INSPECTION OPTIONAL ACCESSORIES

- Getting Started

INTRODUCTION FRONT AND REAR PANEL CONFIGURATION, BASIC FRONT PANEL OPERATION.

Current Measurements V/I Ohms Measurements (Model 487)

BASIC IEEE-488 OPERATION. .......................

Current Measurements Over the Bus V/I Ohms Measurements Over the Bus (Model 487)

...................................

............................

3 - Front Panel Operation

.................

...............

................

.......

...

.................

.........

..............

2-l 2-l 2-5 2-6 2-6 2-9 2-11 2-11

3.1

3.2

3.2.1

3.2.2

3.2.3

3.2.4

3.2.5

3.2.6

3.2.7

3.3

3.4

3.5

3.5.1

3.5.2

3.5.3

3.5.4

3.5.5

3.5.6

3.6

3.6.1

3.6.2

INTRODUCTION. POWER-UP PROCEDURE

Line Voltage Setting Fuse Replacement Power Cord Power up Sequence Default Conditions Line Cycle Integration

Warm up Period

ERROR MESSAGES DATA ENTRY; BASIC RULES

CURRENT MEASUREMENTS.

Current Ranges. Autorange Zero Check and Correct. Filters

Rel......................................

Current Measurements

USING THE VOLTAGE SOURCE (Model 487)

Test Fixture and Interlock Adjusting V-Source Level

3-l 3-1 3-l 3-l 3-2 3-2

3-2 3-3 3-3 3-3 3-4 3-5 3-5 3-5 3-5 3-6 3-7 3-8 3-10 3-10 3-11

3.6.3

3.6.4

3.6.5

3.6.6

3.7

3.8

3.8.1

3.82

3.8.3

3.8.4

3.8.5

3.8.6

3.8.7

3.8.8

3.8.9

3.8.10

3.9

3.9.1

3.9.2

3.9.3

3.9.4

3.9.5

3.10

3.10.1

3.102

3.11

3.11.1

3.112

3.11.3

3.12

3.13

3.14

3.14.1

3.14.2

3.15

3.15.1

3.15.2

3.16

3.16.1

3.16.2

3.16.3

3.16.4

3.16.5

3.16.6

3.16.7

3.16.8

Preset .............................................................................

I-Limit .............................................................................

Operate ............................................................................

Basic V-Source Operating Procedure.

V/I OHMS MEASUREMENTS (Model 487)

..................................................

..............................................

MENU ..............................................................................

DataStore .........................................................................

DataRecall .........................................................................

I-Limit(Model487) .................................................................

Integration .........................................................................

IEEE-488AddressorTalk.Only .......................................................

Defau~s ...........................................................................

Self-Test ...........................................................................

Debug .............................................................................

Calibrate ...........................................................................

CalVSRC(Mode1487) ..............................................................

FRONTPANELTRIGGERING .........................................................

TriggerMode .......................................................................

TriggerInterval...............................................................~

TriggerDelay .......................................................................

Trigger Sources

.....................................................................

Trigger Examples ...................................................................

EXTERNAL TRIGGERING.

............................................................

ExternalTrigger ....................................................................

Meter Complete ....................................................................

DATASTORE ........................................................................

Storing Data at Programmed Intervals, ................................................

Triggering One-shot Readings into Data Store

..........................................

RecallingData ......................................................................

ANALOGOUTPUT ...................................................................

TALK-ONLY .........................................................................

OPERATINGEXAMPLES .............................................................

Measuring Current Generated by an LED ..............................................

Resistivity Tests (Model 487) .........................................................

SOURCE VOLTAGE/MEASURE CURRENT (Model 487). .................................

Basic Source V/Measure I Configuration.

..............................................

Testing2-TerminalDevices ...........................................................

MEASUREMENT CONSIDERATIONS ..................................................

Source Resistance. ..................................................................

SourceCapacitance ..................................................................

Triboelectric and I’iezoelectric Effects. .................................................

Electrostatic Interference. ............................................................

ThermalEMFs ......................................................................

Electromagnetic Interference (EMI). ...................................................

GroundLoops ......................................................................

Floating Measurements

..............................................................

.....

3-12 3-13 3-13 3-13 3-14 3-16 3-16 3-17 3-18 3-18 3-19 3-19 3-19 3-20 3-20 3-20 3-20 3-20 3-21 3-21 3-21 3-22 3-22 3-23 3-23 3-23 3-23 3-24 3-25 3-25 3-27 3-27 3-27 3-29 3-31 3-31 3-32 3-33 3-33 3-33 3-34

3-35 3-35 3-35 3-35 3-36

SECTION 4

- IEEE-488 Reference

4.1

4.2

4.2.1

4.2.2

4.2.3

4.2.4

4.2.5

4.2.6

4.2.7

4.2.8

4.2.9

4.2.10

4.2.11

4.2.12

4.2.13

4.2.14

4.2.15

4.2.16

4.2.17

4.2.18

4.2.19

4.2.20

4.2.21

4.2.22

4.2.23

4.2.24

4.3

4.3.1

4.3.2

4.3.3

4.3.4

4.3.5

4.3.6

4.3.7

4.3.8

4.4

4.5

4.6

4.7

4.7.1

4.7.2

4.7.3

4.8

INTRODUCTION DEVICE-DEPENDENT COMMAND PROGRAMMING

A-Display Intensity B-ReadingSource

C . Zero Check and Zero Correct. ....................................................

D-Display. F-V/IOhms G-DataFormat H-HitControl

J-Self-Tests. ......................................................................

K . EOI and Bus Hold-Off. ..........................................................

L-Default Condlhons or Calibration. ................................................

M - SRQ Mask and Serial Poll Byte Format N-DDataStore;ArmandSetSize.. 0-Operate(Mode1487)

P-Filters Q-Interval

R-Range .........................................................................

S~IntegrationPeriod T-Trigger

u-status .........................................................................

V-VoltageSource

W~Delay .........................................................................

X-Execute Y-Terminator Z-Relative

GENERAL BUS COMMANDS. .........................................................

REN(RemoteEnable)

IFC (InterfaceClear) .................................................................

LLO(LocalLockout)

GTL (Go To Local) and Local .........................................................

DCL(DeviceClear)

SDC(SelectiveDeviceClear) GET (Group Execute Trigger) SPE, SPD (Serial Polling)

IEEE-488BUSCONNECTIONS PRIMARY ADDRESS SELECTION CONTROLLER PROGRAMMING

FRONT PANEL ASPECTS OF IEEE-488 OPERATION .....................................

Front PanelError Messages

IEEE-488 Status Indicators. ...........................................................

LOCALKey

BUS DATA TRANSMISSION TIMES ....................................................

.....................................................................

...................................

...............................................................

.................................................................

......................................................................

...................................................................

....................................................................

............................................

...................................................

............................................................

.........................................................................

.......................................................................

...............................................................

........................................................................

.................................................................

........................................................................

.....................................................................

.......................................................................

................................................................

.................................................................

..................................................................

.........................................................

.............................................................

.........................................................

......................................................

...........................................................

........................................................................

4-l 4-1 4-6 4-7 4-8 4-9

4.10 4-11 4-15 4-16 4-17

4.19 4-21

4-24

4.26 4-27 4-28 4-29 4-30

4.31 4-32 4-38 4-39 4-40 4-41 4-42 4-44 4-44 4-44 4-45 4-45 4-45 4-45 4-45 4-46 4-46 4-47 4-48 4-48 4-48 4-50 4-51 4-51

SECTION

5 - Performance Verification

5.1 INTRODUCTION

5.2 ENVIRONMENTALCONDITIONS

5.3 INITIALCONDITIONS

5.4 REQUIREDTESTEQUIPMENT

5.5 VERIFICATION PROCEDURES ........................................................

5.5.1 PicoammeterVeri~cation..

5.5.2 Voltage Source Verification (Model 487). ...............................................

SECTION 6

6.1

6.2 ANALOG CIRCUITS.

6.2.1 Input Amplifier.

6.2.2 Analog Filter

6.2.3 Multiplexer . ..__. .., ., ,., ._, ,_

6.2.4 +2.8V Reference

6.2.5 Analog Output

6.2.6 Voltage Source (Model 487).

6.3 ANALOG CONTROL CIRCUITRY.

6.4

6.5 DIGITAL CIRCUITS

6.5.1

6.5.2

6.5.3 Display/Keyboard.

6.5.4 IEEE-488 Interface .

6.6 POWER SUPPLIES

6.6.1 ACLineInput..........................

6.6.2

6.6.3

6.6.4

- Theory of Operation

INTRODUCTION

A/D CONVERTER

Digital Block Diagram. Microcomputer

*15V Supplies +5VA Supply. . +6.5V Supply.

....................................................................

.....................................................

...............................................................

........................................................

..........................................................

. .

5-l 5-l 5-1 5-l 5-2 5-2 s-4

6-l 6-1 6-1 6-2 6-3 6-3 6-5 6-5 6-6 6-8 6-9 6-9 6-11 6-12 6-13 6-14 6-14 6-14 6-14 6-14

SECTION

7.1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . .._.

7.2 LINE FUSE REPLACEMENT.

7.3

7.3.1

7.3.2

7.3.3

7.3.4 Warm-Up Period.

7.3.5 Front Panel Calibration

7.3.6 IEEE-488 Bus Calibration . .

7.4 HANDLING AND CLEANING PRECAUTIONS

7.5 DISASSEMBLY................................

7.5.1 CoverRemoval..............................

7.5.2 Shield Removal.

7 - Maintenance

CALIBRATION.

Recommended Calibration Equipment. Environmental Conditions CAL LOCK Switch.

7-1 7-l 7-1 7-1 7-2 7-2 7-2 7-2 7-6 7-8 7-9 7-9 7-11

7.5.3

7.5.4

7.6

7.7

7.7.1

7.7.2

7.7.3

7.7.4

7.7.5

7.7.6

7.7.7

Front Panel Removal

Circuit Board Removal.

................................

..............................

SPECIAL HANDLING OF STATIC SENSITIVE DEVICES TROUBLESHOOTING

Recommended Troubleshooting Equipment Self-Test

...........................................

Analog Control Lines. A/D Test Mode Troubleshooting Procedures Input Offset Voltage Adjust. Fusible Resistor Replacement,

................................

............

...............................

.....................................

..........................

........................

..........

7-11

7-11 7-11 7-12 7-12 7-12 7-12 7-13 7-13 7-19 7-19

SECTION

8.1

8.2

8.3

5.4

8.5

8 - Replaceable Parts

INTRODUCTION........................................................

PARTSLISTS............................................................

ORDERINGINFORMATION..............................................

FACTORYSERVICE......................................................

SCHEMATIC DIAGRAMS AND COMPONENT LOCATION DRAWINGS.

APPENDICES

C ASCII Character Codes and IEEE-488 Multiline Interface Command Messages.

D E

Device-dependent Command Summary Interface Function Codes.

Controllerrrograms.......................................................

IEEE-488BusOverview....................................................

8-l 8-l 8-l 8-l 8-l

A-l B-l C-l D-l

E-l

List of Illustrations

SECTION 2 - Getting

Figure 2-l Figure 2-2 Figure 2-3 Figure 2-4 Figure 2-5

Figure 2-6

SECTION 3

Figure 3-l Figure 3-2 Figure 3-3 Figure 3-4 Figure 3-5 Figure 3-6 Figure 3-7 Figure 3-8 Figure 3-9 Figure 3-10 Figure 3-11 Figure 3-12 Figure 3-13 Meter Complete Specifications.

Figure 3-14 Figure 3-15 Figure 3-16 Figure 3-17 Figure 3-18 Figure 3-19 Figure 3-20 Figure 3-21 Figure 3-22 Figure 3-23

Figure 3-24

Model 486 Front Panel. Model 487 Front Panel. Model 486 Rear Panel. Model 487 Rear Panel. Connections to Measure Current. Connections for V/I Ohms Measurements

- Front Panel Operation

Line Voltage Switch and Line Fuse

Data Entry.. .....................................................................

Trim Input Connector (3-Lug)

Picoammeter Connections. Model 487 V-Source Output Terminals,

InterlockConnections.. ...........................................................

InterlockConnections .............................................................

V-SourceAdjust ..................................................................

Basic V-Source Connections V/I Ohms Connections (Source V Measure I)

TriggerConnectors ................................................................

External Trigger Pulse Specifications.

Typical Analog Output Connections. Setup for MeasureLED Current Connections for Resistivity Test, Configuration for Surface Resistivity Configuration for Volume Resistivity

Simplified Model from Source Resistance and Source Capacitance Effects

TriboelectricEffect ................................................................

PiezoelectricEffect ................................................................

Multiple Ground Points Create a Ground Loop Eliminating Ground Loop. Improper Method to make Floating Measurements.

Started

.........................................................

........................................................

.........................................................

..................................................

......................................................

..............................................

.........................................

................................................

.....................................................

................................................

.....................................................

....................................................

................................................

.......................................

...................................

................

2-2 2-3 2-4 2-5

2-7

2-8

3-l 3-4 3-8 3-9 3-10 3-11 3-11 3-12 3-14 3-15 3-23

3-23 3-23 3-26 3-29 3-30 3-30 3-31 3-33 3-34

3-34 3-35 3-36 3-36

SECTION

Figure 4-1 Figure 4-2 Figure 4-3 Figure 4-4 Figure 4-5 Figure 4-6

Figure 4-7

4 - IEEE-488 Reference

ASCII Data Format (G2; Prefix and Suffix). G6 and G7 Binary Data Formats (Counts/Exponent). G4 and G5 Binary Data Formats (IEEE Std. 754). Headers For Binary Formats. SRQ Mask and Serial Poll Byte Format. UO Machine Status Word (Factory Defaults Shown). Ul Error Status Word.

4-11 4-12 4-12

4-13 4-21 4-33

4.34

Figure 4-8 Figure 4-9 Figure 4-10 Figure 4-11

U9 Voltage Source Error Status Word IEEE-488 Connector. IEEE Connections.

.......................

IEEE-488 Connector Location.

Figure 4-12 Contact Assignments.

.....................

.............

....................

.......

..........

. . . .

. . .

4-36 4-46 447 4-47 4-47

SECTION

5 -Performance Verification

Figure 5-l Setup for Picoammeter Verification. . . Figure 5-2 Setup for Voltage Source Verification (Model 487)

SECTION 6

Figure 6-1 Figure 6-2

Figure 6-3 Figure 6-4 Figure 6-5

Figure 6-6

Figure 6-7 Figure 6-8 Figure 6-9 Figure 6-10

Figure 6-11

Figure 6-12 Figure 6-13 Figure 6-14 Figure 6-15

Figure 6-16

Figure 6-17

- Theory of Operation

Overall Block Diagram Simplified Model of Input Amplifier Zero Check Configuration Offset Voltage Adjust Circuit Analog Filter Circuitry

Multiplexer .............................

Multiplexer Phases. Analog Output Circuit (Simplified) . Simplified Model of V-Source (Model 487) Analog Control Circuitry Control Word

...........................

A/D Converter Simplified Schematic. Digital Block Diagram. Memory Map

...........................

Simplified Block Diagram of Serial Port. Display Block Diagram. Power Supply Block Diagram

...................

.......

................

..............

...................

......................

.................

...................

....

..................

.............

.......

5-3 5-5

6-l 6-2 6-2 6-2 6-3 6-4

. 6-5

. . . ..I. . 6-5

6-5 6-7 6-8 6-9 6-10 6-11

. .

6-12 6-13 6-14

SECTION 7

Figure 7-l

- Maintenance

Cal Lock Switch Figure 7-2 Setup for Picoammeter Calibration. Figure 7-3

Setup for Voltage Source Calibration (Model 487)

Figure 7-4 ExplodedView..................................

Figure 7-5 Test Point, R198 and R203 Locations,

Figure 7-6 Integrator Output (Typical)

APPENDICES

Figure E-l Figure E-2 Figure E-3

IEEE-488 Bus Configuration.

IEEE-488 Handshake Sequence

Command Codes

........................

..............

............

.......

. . . . . .

7-2 7-4 7-5 7-10 7-14

7-17

E-2

E-3

E-6

.......

..........

List of Tables

SECTION

Table 2-l

2 - Getting Started

SECTION 3

Table 3-l Table 3-2 Table 3-3 Table 3-4 Table 3-5 Table 3-6 Table 3-7 Table 3-8 Table 3-9 Table 3-10 Table 3-11

SECTION 4

Table 4-l Table 4-2

Table 43 Table 4-4 Table 4-5 Table 46 Table 4-7

Abbreviated Command Summary.

- Front Panel Operation

Line

Voltage

LineFuseSelection Factory Default Conditions (Front Panel). Error Messages.. CurrentRanges Analog Filter Effects. Model 487 V-Source MENU Items Typical Analog Output Values Minimum Recommended Feedback Capacitor (CF) Values.

Selection (50.60~2)

................................................

.................................................

...................................................

....................................

- IEEE-488 Reference

Device-dependent Command Summary Typical Bus Holdoff Times Factory Default Conditions. IEEE Contact Designations. HP BASIC 4.0 IEEE-488 Statements. IEEE-488 Error Messages. Typical Trigger to First Byte Out Times.

............................

.....................

.............

,,....

.,....

,.....

,_....

,....,

2-10

3-l

3-2 3-3 3-4 3-5

3-6

3-10

3.17

3.26 3-33

3-33

4-2 4-18

4.19

444

4-48

4-49

4-51

SECTION

Table 5-1 Table 5-2

SECTION 6

Table 6-l Table 6-2

SECTION

Table 7-l Table 7-2 Table 7-3 Table 7-4 Recommended Troubleshooting Equipment

5 - Performance Verification

VerificationEquipment............................................................

Picoammeter Verification

- Theory of Operation

RangeRelays Filter Relay Switching

.....................................................................

.............................................................

7 - Maintenance

LineFuseSelection CalibrationEquipment Picoammeter Calibration.

................................................................

............................................................

..........................................................

..........................................

5-l

5-3

6-2 6-4

7-l 7-2 7-3

7.12

Table 7-5

PowerSupplyChecks

Table 7-6 Digital Circuitry Checks

................................................

..............................................

Table 7-7 Analog Circuitry Checks. .............................................

Table 7-8

V-Source Checks (Model 487 Only).

....................................

APPENDICES

...........

7-14 7-15 7-16 7-18

Table A-l Table B-l Table D-l Table E-l Table E-2 Table E-3 Table E-4 Table E-5

Device-dependent Command Summary Model 486/487 Interface Function Codes

........................

.......................

BASIC Statements Necessary to Send Bus Commands IEEE-488 Bus Command Summary. Hexadecimal and Decimal Command Codes Typical Addressed Command Sequence Typical Device-dependent Command Sequence. IEEE Command Groups

......................................

............................

....................

........................

.................

............

...........

A-l B-l

D-3

E-4 E-7

E-7

E-7 E-8

SECTION 1

General Information

1.1 INTRODUCTION

This section contains general information about the Model 486 Picoammeter and the Model 487 Picoammeter/vo1tage S&we.

1.2 FEATURES

Some important Model 486/487 features include:

DualDisplays-Alocharacteralphanumericdisplay used for current readings and front panel messages, and a smaller 8 character alphanumeric display for front panel messages and the voltage source setting of the Model 487. zero correct - used to cancel internal offsets. Relative @EL) -Used to establish baselines. DataStore-CCanstoreupto512readingsandisaccessible over the bus 01 from the front panel. User Programmed Default Conditions - Establish present operating setup conditions as power-up de fault conditions. Talk-Only - From the front panel, set instnmwnt to send readings over the bus to a listen-only device, such as a printer. V/I ohms resistance measurements up to 5OPQ (Model 487 only). Preset (Model 487) toggles between preset V-source values

1.4 MANUAL ADDENDA

Any improvements or changes concerning the instrument or manual will be explained in an addendum included with the manual. Be sure to note these changes and incorporate them into the manual.

1.5

The following symbols and terms may be found on an instrument or used in this manual.

The A

should refer to the operating inskwiions located in the instmction manual.

The WARNING heading used in this manual explains dangers that might result in personal injmy or death. Always read the assodated information very carefully before performing the indicated procedure.

The CAUTION heading used in this manual explains hazards that could damage theinstnunent. Such damage may invalidate the warranty.

SAFETY SYMBOLS and TERMS

symbol on an insinunent indicates that the user

1.6 SPECIFICATIONS

Model 486/487 specifications may be found at the front of this manual.

1.3 WARRANTY INFORMATION

Warranty information is located on the inside front cover

of this inskwtion manual. Should your Model 486/487

require warranty service, contact the Keithley represen-

tative or authorized repair facility in your area for further information. when returning the instrument for repair, be sure to fill out and include the service form at the back of this manual in order to provide the repair facility with the necessary information

1.7 INSPECTION

The Model 486/487 was carefully inspected, both electrically and mechanically before shipment. After unpacking all items from the shipping carton, check for any obvious signs of physical damage that may have occurred during transit. Report any damage to the shipping agent immediately. Save the original packing carton for possible future reshipment. The following items are included with every Model 4%/487 order.

l-l

SECTION 1 General Information

Model 486 Picoammeter or Model 487 Picoammeter/ Voltage Source. Model 486/487 Instruction Manual. Model 2.36~IX-3 Interlock Cable (Model 487 only) Model 237-ALG-2 Triax to Alligator-clip Cable. Quick Reference Guide Additional Accessories as ordered.

If an additional instnxtion

manual

is required, order the manual package, Keithley part number 486-901-00. The manual package includes an instruction manual and any pertinent addenda.

1.6 OPTIONAL ACCESSORIES

The following accessories are available use with the Model 486/487.

Model 4.288-l SingleFixed RackMount Kif -Mounts a sin-

gle Model 486/487 in a standard 19 inch rack.

from

Keithley for

Model 61713~slot to.Z-lug Triax Adapter- Adapts INPUT

connector for 2slot triax cables.

Model 7007 Shielded IEEE-488 Cables - Connects the

Mode1486/487 to the IEEE-488 bus using shielded cables

reduce electromagnetic interference @Ml). The Model 7007-l is one meter in length and has an EMI shielded IEEE-488 connector at each end. The Model 7007-2 is identical to the Model 7007-1, but is two meters in length.

Model 7078-TRXTriaxiaJ Cables-Low noise cables terminated with 3&t male triaxial cormectors. The Model 7078~TRX-3 is

O.Qm

(3 ft.) in length, the Model

7078TRX-10 is 3m (10 ft.) in length, and the Model

7078-TRX-20 is 61x1(20 ft.) in length.

Model 8002A High Resistance Test Fixture -Use with the Model 487 to make high resistance W/II measurements. The Model 8002 is designed to minimize leakage currents that could otherwise degrade the measurement. Connectors in&de one pair of 5-way binding posts, two 3-lug biaxial connectors, and a standard interlock connector for the safety interlock switch.

Model 4288-2 DwJ Fixed Rack Mount Kit - Mounts two Model 486/487s in a standard 19 inch rack.

Model 61 OS Resistivity Chamber -Use with the Model487

to measure the volume and surface resistivity of test samples. Accommodates sheet samples 64 to 102mm (2.5 to 4 in.) in diameter and up to 6.4mm (0.25 in.) thick.

Model 8006 Component Test Fixture-Provides a convenient and practical way of making sensitive test measure-

ments

on a variety of standard packaged devices. Sockets are provided for resistors, diodes, 4-, 8; IO-, and 12-lead axial (TO) packages, and DIPS up to 28 pins. Connectors

include 16 3-lug triaxial, two BNC, five 5-way binding posts, and a standard interlock connector for the safety

interlock switch.

1-z

SECTION 2

Getting Started

2.1 INTRODUCTION

This section contains introductory information on using the Model 486 Pico-eter and the Model 487 Picoammeter/Voltage Source. For detailed front panel and IEEE-488 bus operation, refer to Sections 3 and 4 mpeclively.

2.2 FRONT AND REAR PANEL CONFIGURATION

Figure 2-1 and Figure 2-2 show the respective front panek of the Models 486 and 487, while Figure 2-3 and Figure 2-4 show the respective rear panels. Each of these figures includes important information that should be reviewed before operating the instrument.

2-l

SECllON 2 Getting Started

l-lx-ml

Ygure 2-1. Model 486 Front Panel

2-2

SECTION 2

Getting started

gure 2-2.

Model 487 Front Panel

2-3

SECTION 2 Getting Started

3-lug Triax Current input

Trigger Connections

An;og

Output Binding

Posts

Chassis Ground

3inding Posts

IEEE-438 Connector

BNC

Calibration Switch

(sticker cows access hole)

In = Calibration enabled

Out = Calibration disabled

Note : Use shielded IEEE-488 cable

Line Fuse

CAUTION : Replac- .___ with one of same type ant rating : WA, 90-125V

114

Line Power Input WARNING : Connect to grounded outlet using 3-wire power cord

& Line Voltage Switch

1 105W125V

21 O-250V

(Optional transformer required for 90-l 1 OV,

1 SO-220V operation) CAUTION : Operation on improper line voltage may damage unit

A, 180.250V

‘igure 2-3.

Model 486

Rear

Panel

2-4

Binding Post

Fipre 2-4.

Interlock

Cur& input r0s’s

Model 487 Rear Panel

IEEE-488 Connector

Note : Use shielded IEEE-488 cable

1 Out = Calibration disabled 1

Line Fuse CAUTION : Replace fuse with one of 8ame type and rating : f/z?A. go-12Sv

l/4 A, 180-250v

SECTION 2

Getting Started

Line Power Input WARNING : Connect to grounded outlet using %wirs power cord

- Line Voltage Switch 105v-125v

210-250” ,n^+;..“..l ‘-41rmer

~~l-.~--.-. -_ .lOV,

1 SO-22OV operation) CAUTION : Ooeration on Improper I& Voltage may damage ““II

2.3 BASIC FRONT PANEL OPERATION

The following presents the basic information needed to use the Model 486/487 to make current measurements. For the Model 487, a procedure to use the voltage source in conjunction with the picoammeter is provided to demonstrate V/I Ohms resistance measurements.

NOTE

Make signal input low connections only to

II’UT LO. Do not use ANALOG OUTPUT

LO for input connections.

Before attempting to operate the instrument, verify that the rear panel line voltage switch is in the correct position for the power line voltage in your area. Connect the instrument to an appropriate power source using the supplied line cord, then turn on the power by pressing in the front panel POWER switch.

WARNING Use only a grounded ac outlet to avoid a possible shock hazard.

CAUTION Operating the instrument an an incorrect line voltage may cause damage to the instrument.

NOTE If the front panel display should appear to be inoperative,

try pressing the DISPLAY INTENSITY key once or twice to restore the display to normal intensity.

2-5

SECTION 2 Getting Started

2.3.1

The steps below outline the basic procedure for using the Mode1486/487 to make current measurements from the front panel:

Current Measurements

Perform factory initialization as follows to return the instnunent to factory default conditions:

Press and rele&e MFNIJ until the following

message is displayed:

DEFAULTS

Use the rotary knob, or the4 and b keys to display the following message:

DEFAULTS FACTORY

Press MENU. The instrument will return to the

normal IneasuTement display state.

Note: Performing factory initialization is a convenient method to return the instrument to typi-

cally used operating states. Using factoiy defaults, zero check is enabled, autorange is enabled, and filter (digital + analog) is enabled.

Connect the rear panel triax INPUT connector to the current source. For example, Figure 2-5 shows a Keithley Model 263 source connected to the Model 486/4si On the Model 486/487, press SHIFT and then COR-

RECT to perform zero cormztion. This will cancel

ally inted offsets.

On the Model 486/487, disable zero check by pressingZEROCHECK.The~OCHECKindicatorwill turn off. If you intend to suppress an offset current from the

external current source, perform the following steps:

A. Apply the current to be suppressed to the input.

That current will be measured and displayed on

the Model 4861487.

B. On the Model 486/487, press REL. The current

will be suppressed as indicated by the zeroed

display. Apply the signal current to be measured to the input of the Model 486/487. Read the current measurement on the display of the

Model 486/487.

When the measurement is complete, enable zero check to avoid accidental overloads to the instrument. In general, zero check should be left enabled while the instrument is tuned on but not in use.

2.3.2 V/I Ohms Measurements (Model 487)

NOTE The following procedure demonstrates how to properly use the V-Source of the Model 487. Keep in mind that the V-Source can be used as an &dependent source for any appropriate application.

For V/I Ohms resistance measurements, the Model 487 sources a voltage to a device under test (DUT) and measures the subsequent current. The resistance value of the

DLIT is automatically calculated (R = V/I) and displayed

in ohms.

The steps below outline the basic procedure for using the Model 487 to make V/I Ohms measurements from the front panel:

1. Performfactory initializationasfollows toretumthe instroment to factors default conditions:

Press and relea;e MENU until the following

message is displayed:

DEFAULTS OK

Use the rotary knob, or the 4 and b keys to dis-

play the following message:

DEFAULTS

Press MENU. The instrument WiII return to the

normal measurement display state. Note: Performing factory initition is a con-

venient method to return the instrument to typically used operathg states. Using factory defaults, zero check is enabled, autorange is enabled, filter (digital + anslog) is enabled, I-limit is set to 2.5mA.

2. SelecttheV/IOhmsfunctionbypressingSHIFTand

then OHMS (v/I).

3. With the DUT installed in an appropriate test fixture,

connect it to the V-Source and picosmmeter of the Model 487. Figure 2-6 shows how to connect a DUT that is installed in the Keithley Model 8002A t&t fixture to the Model 487.

WARNING

To prevent contact with possible hazardous

voltages, make sure the Model 487 interlock

FACTORY

2-6

Equivalent Circuit

SECTION2

Geffina Sfarfed

2igure 2-5.

Connections to Measure Current

is properly connected to the test fixhm (see Figure Z-6). With proper use of Interlock, the V-Source will not apply voltage to the test fixture when the lid of the test fix&m is

OPm

WAlZNlNG

To provide protection from shock hazards, the test fixture chassis must be properly con-

nected to a safety earth ground. A grounding wire (18 AWG or larger) must be attached se-

curely to the test fixture at a sczew temdnal designed for safety grounding. The other end of the ground wire must then be attached to a known safety earth ground.

Guard

Disabled

5. Set the V-Source of the Model 487 to the desired voltage level as follows:

A. Select the V-Source range. To select the 50V

range, keep pressing and releasing the, key until the 3JV mnge is displayed (i.e. OV on the 5OV range is displayed as “OO.OWJ”). To select the 500V range, keep pressing and releasing the 4 key until the 5CW range is displayed (i.e. OV on the SOOV range is displayed as “OOO.OOV”).

B. Use the 4 and b keys to position the cursor

Washing digit, on the digit to be modified.

C. Use the rotary knob to increase or decrease the

voltage level from the selected digit.

Note: As a general rule, the V-Source should be set as high as possible to optimize V/I Ohms measurement accuracy.

4. On the Model 487, press SHIFT and then CORRECT to perform zero correction. This will cancel any internal offsets.

6. On the Model 487, press ZERO CHECK to disable zero check, and press OPERATE to apply the pmgr-ed voltage to the test fixture. The resistance of

2-7

SECTION2 Getting Started

the DLT will be measured and displayed on the Model 487.

Note: Usingthe setup in Figure 2-6, resistance will be displayed as a positive value. As long as both current and voltage read positive (or both read negative), then the V/I calculation wilI be displayed positive. Negative V/I is displayed only if the V-Source or

.-- 70BTRX Cable

r;--1

----_---

pica-eter (but not both) have a negative read

out. V/I Ohms is simply the calculation of voltage

setting divided by meter reading.

7. When finished, place the V-Source in standby and enable zero check.

31 I

~.__.._

il r----7 Ii LO

L-----------2

Model 8WZA

Connecfions for V/I Ohms Measurements

Ii .-

"ewroe

2-8

SECTION 2

Getting Started

2.4 BASIC IEEE-488 OPERATION

The following information outlines the basic procedures to use the Model 486/487 over the IEEE488 bus. An abbreviated summary of commands necessary for basic op-

eration is shown in Table 2-1. Simple controIler programs thatcanbeused tosendthesecommand.sarelistedinAppendix D of this manual.

Before attempting to operate the inshument, perform the following steps:

With the power off, connect the Model 486/487 to the IEEE-488 bus of the controller. A shielded IEEE-488 cable such as the Keithley Model 7007 is recommended.

Verify that the rear panel line voltage switch is in the correct position for the power line voltage in your area. Connect the in.9troment to an appropriate power source using the supplied line cord, then turn on the power by pressing in the front panel POWER switch.

WARNING

Use only a grounded ac outlet to avoid a pos-

sible shock hazard.

CAUTION operating the instrument on an incorrect line voltage may cause damage to the ins&u-

NOTE If the tiont panel display should appear to be inoperative, try pressing the DISPLAY II+ TFNSITY kev once or twice to restore the display to non&l intensity.

Verify that the programmed primary address dis-

played on power-up is the same as the one you intend to specify in your program statements. For example, if the instnunent is currently set for an address of 22, the following message wiIl be briefly displayed on power-up.

IEEE-488

If you desire to change the primary address of the in-

ADDR 22

strument, you can do so as follows: A. Press and release MENU untiI the IEEE-488 ad-

dress is displayed.

B. Use the rotary knob (or the4 or, key) to display

the desired address (O-30).

C. With the desired address displayed, press

MENU to save it.

D. Press SHIFT and then EXIT to return to normal

operation.

2-9

SECTION 2

Getting Started

Lnnmand Description

Table 2-l. Abbreviated Command Summary

30 3 2

TO ?l

xl 21 22 3,v A 3 ,6

30 31

?I iit

B RO E Ei

u5 Fz

U8 FO

Disable zero check Enable zero check Enable zero check and perform zero correction

Disable V/I ohms &lode1 487) Enable V/I ohms (Model 487)

Return to factory default conditions and save (Ll) Save present states as default conditions Return to saved default conditions Calibrate present messuwnent range using W’; v = -2E-3 to +2E-3 amps Calibrate zero on present voltage source range (Model 487) Caliirate full scale on present voltage souxe range (Model 487) Prepare to calibrate present voltage source range (Model 487)

Place Model 487 V-Source in standby Place Model 487 V-Source in operate

Disable digital and analog filters Enable digital filter; disable analog filter Disable digital filter; enable analog filter

Enable digital and analog filters

Enable autorange

Select 2nA range

Select 2OnA range

Select 2OOnA range

Select 2@ range

select 2o)lA mlge

Select 200@ range

select 2mA range

No range

Disable autorange

Z-10

Vll,r,l

Specify voltage source (Model 487) level “n” in volts, range “I” and limit “1”;

n: -505.000 to +505.000

r: 0 = 50V range; I= 500V range

1:0=2?+4limit;1=2.5mAlimit

X Execukother device-dependent commands

Disable relative E z2,v

Enable relative using present reading as baseline

Enable relative using “v” as baseline;

Y = -2E-3 to +2E-3 amps for current

Y = OR to 5.OSEXQ for V/I ohms z3

Enable relative using baseline previously defined.

SECTION 2

Getting Started

2.4.1 Current Measurements Over the Bus

Perform the following steps to make current measurements over the bus:

Boot up your computer and load your test program (again, see Appendix D for programs that can be

used to send commands).

NOTE NOTE If using a program from Appendix D, a read- If using a program from Appendix D, a reading will be sent to the computer and displayed ing will be sent to the computer and displayed every time you input a command string. every time you input a command string.

Send the following command to perform factory in-

2. itialization:

LDX

Performing factory initialk&ion is a convenient

method to return the instrument to typicslly used operating states. With factory defaults, zero check is enabled, autorange is enabled, and filter (digital + analog) is enabled.

Set the external current source to apply the signal

current to be measured to the input of the Model 486/487. The current measurement is displayed on the Model 486/487. To send and display the reading on the

computer CRT, the Model 486/487 must be ad-

dressed to talk. When finished, enable zero check by sending thefollowing command:

2.4.2

V/I Ohms Measurements Over the Bus (Model 487)

For V/I ohms measurements, the Model 487 sources a voltage to a device under test (DLIT) and measures the subsequent current. The resistance value of the DUT is automatically calculated CR = V/I) and displayed.

Perform the following steps to make V/I ohms measurements over the bus:

Boot up your computer and load your test program

(again, see Appendix D for programs that can be

used to send commands).

Connect the rear panel triax INPUT comector to the current source. For example, Figure 2-5 shows a Keithley Model 263 source connected to the Model

486.

To cancel internal offsets, send the following com-

mand to perform zero correction:

c2x

Disable zero check by sending the following command:

cox

If you intend to suppress an offset current external current source, perform the following steps:

A. Apply the current to be suppressed to the input.

That current will be measured and displayed on

the Model 486/487.

B. Send the following command to perform sup-

pression:

ZlX

from

the

NOTE If using a program from Appendix D, a reading will be sent to the computer and displayed every time you input a command string.

Send the following command to perform factory initialization:

LOX

Performing factory initialization is a convenient method to return the instrument to typically used operating states. With factory defaults, zero check is enabled, autorange is enabled, filter kligital + analog) is enabled, and I-limit is set for 2.5mA.

Select the V/I ohms function by sending the follow-

3. ing command:

FlX

With the DUT installed in an appropriate test fixture,

4. connect it to the V-Source and picosmmeter of the Model 487. Figure 2-6 shows how to connect a DIlT

2-11

SEClYION 2

Getting Started

that is installed in the Keithley Model 8002A test fiwture to the Model 487.

WARNING

To prevent contact with possible hazardous

voltages, make sure the Model 487 interlock

is properly connected to the test fixture (see Figure 2-6). With properuse of Interlock, the V-Source will not apply voltage to the test fixture when the lid of the test fixture is open.

WARNING

To provide protection from shock hazards,

the test fixture chassis must be properly connected to a safety earth ground. A grounding wire (18 AWG or larger) must be attached securely to the test fixture at a screw terminal designed for safety grounding. The other

end of the ground wire must then be attached to a known safety earth ground.

To cancel internal offsets, send the following

mand to perform zero correction:

com-

Use the

V command to program the V-Source. For example, to set the V-Source for lOV, send the following command string:

VIOX

Note: Asageneralrule,theV-Sourceshould beset as high as possible to optimize measurement accuracy.

Disable zero check by sending the following com-

man&.

cox

To source voltage to the DUT, place the V-Source in operate with the following command:

01x

The resistance measuement is displayed on the

Model 487. To send and display the reading on the

computer CRT, the Model 487 must be addressed to talk.

10.

When finished, enable zero check and place the V-

Source in standby by sending the following command string:

C2X

CIGQX

Z-12

SECTION 3

Front Panel Operation

3.1 INTRODUCTION

This section contains the detailed information necessary to use the insttument from the front panel. These operations (except for IEEE-488 address selection and frequency for line integration) can also be programmed over the IEEE-488 bus, as described in Section 4.

3.2 POWER-UP PROCEDURE

3.2.1

The instrument is designed to operate from 10.512%’ or 210-25OV line power ranges. A special transformer may be installed (at factory) for 90-IlOV and lSC-220V ranges. The operating voltage that the instrument is configured to operate at is indicated on the line voltage slide switch located on the rear panel (see Figure 3-l). The required switch positions for the available line voltages are summarized in Table 3-l. If the line voltage setting needs to be changed, proceed as follows:

Table 3-l. Line Voltage Selection (5LMOHz)

Line Voltage Setting

Voltage Selection

Line Voltage

Switch Position

I105-125v I

115v

in the switch slot and slide it over to the alternate position. Install a fuse consistent with the operating voltage,

2. as described in the next paragraph.

Figure 3-1.

Line Voltage Switch and Line Fuse

3.2.2 Fuse Replacement

A rear panel fuse located adjacent to the line voltage

switch (see Figure 3-I) protects the power line input of the instrument If the fuse needs to be replaced (line voltage switch sethg changed or suspected blown fuse), perform the following steps:

WARNING Make sure the instrument is disconnected from the power line and other equipment

before replacing the fuse.

With the power off, place the end of a flat-blade

screwdriver into the slot in the rear panel line LINE FUSE holder. Push in gently and rotate the fuse carrier one-quarter turn counterclcckwise. Release pressure on the holder and its internal spring will push the fuse and carrier out of the holder.

Remove the fuse and replace it with the type recommended in Table 3-2.

WARNING Make sure the Model 486/487 is disconnected from the power line and all other equipment before proceeding.

1. Locate the line voltageswitch on the rear panel (see Figure 31). Place the blade of a screwdriver into slot

CAUTION Donotuse afusewithahighercurrentrating than specified, or instrument damage may occur. If the instrument repeatedly blows fuses, locate and correct the cause of the trouble before replacing the fuse. See the maintenance section for troubleshooting information.

3-1

SECTION 3 Front Panel Operation

Table 3-2. Lie Fuse Selection

3. Install the new fuse and the fuse carrier into the holder by reversing the above procedure.

3.2.3 Power Cord

Connect the female end of the power cord to the ac receptacle on the rear panel of the instrwnent. Connect the male end of the cord to a grounded ac outlet.

WARNING The instrument is equipped with a 3-wire power cord that contains a separate ground wire and is designed to be used with grounded outlets. When proper connections are made, instrument chassis is connected to

powerlineground.Failoretouseagroonded

outlet may result in injury or death due to electric shock.

ROM ERROR RAM ERROR NO DEFLTS

UNCAL

The displayed error message can be cleared by pressing any front panel key. However, a problem exists and needs to be rectified (see troubleshooting information in the Section 7). A brief explanation of any displayed error message is contained in Table 3-4.

NOTE If the instrument is still under wsrrsnty and a problem develops, it should be returned to Keithley Instzuments, Inc. for repair.

2. Assuming the unit successfully passes the self test, it will then briefly display the firmware revision level. For example:

REV AO0.4

The revision level of your unit will probably be different. In any case, the revision level should be recorded in case it becomes necessary to replace the fhmware in the future.

3. Next, the progr-ed primary address will be diiplayed as in the following example:

CAUTION

Be sure that the power line voltage agrees with the indicated range on rear panel line voltage switch. Failure to observe this pre-

cautionmayresultininstnrmentdamagenot

covered by the warranty.

3.2.4

To hxn on the instrument, depress the POWER button. During the power up cycle, the unit will perform the following:

1. Theinstrumentwillperformself-testsonitsmemory lowing error messages will be displayed:

3-2

Power Up Sequence

elements. If a failure occurs, one or more of the fol-

IEEE-%

Atthefactory,theIEEEaddressoftheMode1486and

487 is set to 22. Jf If the address has been changed by

the user, then that address value will instead be disPlay*.

4. The unit will then begin normal operation in accordance with the power up cotiguation discussed in the next paragraph.

3.2.5

Default conditions can be defined as the setup conditions that the instrument will return to when it is powered up (or when a DCL or SDC command is sent over the bus). The instrument will return to either factory default conditions or user saved default conditions.

Default Conditions

ADDRZ!

Front Panel Operation

SEC77ON 3

Factory Default Conditions

At the factory, the Model 486/487 is set up so that the in-

strument is configured to certain setup conditions on the initial power up. These factory default conditions are listed in Table 3-3 (front panel operation) and Table 4-3 (IEEE438 bus operation). If alternate setup conditions are saved (see User Saved Default Conditions), the instrument can be returned to factory default conditions using the DEFAULTS FACTORY menu selection (see paragraph3.8.6) orsendingLOover theIEEE-488 bus (see paragraph 4.2.10).

Table 3-3. Factory Default Conditions (Front

&mtmUFeatme 1 Factory Default Condition Display Intensity” Normal display intensity

Zero Ch& Zero check enabled V/I ohms* V/I ohms disabled Data Store unarmed Operate (487) Voltage source in standby Filters* Digital and analog filter enabled Range* Autorange enabled Integration’ Line cycle; 6OHz Trigger’ Multiple, 175msec interval, Osec

delay Preset+ OV, 50V range, disabled Voltage Source OV level, 50V range and 2.5mA

(4S7)*

Relative*

‘operating aspects of these conimls/feaixres can be saved a* user saved default conditions..

limit

Relative disabled

3.2.6 Line Cycle Integration

When using a line cycle integration period, the line cycle

setting should match the frequency of the power line to

ensure maximum rejection of noise caused by electromagnetic, electrostatic or conducted pickup from power supplies, or power cards and outlets. The instrument will still operate with a mismatched setting, but measure ments will be noisier.

To set the integration period for your line frequency, perform the following steps:

1. KeeppressingandreleasingtheMENUkeyunlilthe following message appears on the large display:

INTEGRATE

2. Use the rotary knob (or4 and b keys) to display the desired line frequency setting on the small display as shown:

INTEGRATE INTEGRATE

LlNE5OHZ LJNE6OHZ

(5OHz setting) WX-Iz setting)

3. Press MENU to select the displayed integration period setting. The next menu item will then be displayed.

4. Exit from the menu by pressing SHIFT and than EXE. The hstmment will return to normal operation

Note: The selected integration period can be saved as the default condition (see paragraph 3.8.6).

3.2.7 Warm Up Period

User Saved Default Conditions

Unique setup conditions can be saved by using the DE-

FAULTS SAVE menu selection (see paragraph 38.6) or

by sending device-dependent comman d Ll over the

IEEE-488 bus. These user saved default conditions will prevail over the factory default conditions on power-up, or when a DCL or SDC is asserted over the bus.

The instrument can be used immediately when it is first turned on. However, the unit must be allowed to warm up for two hours to achieve rated accuracy.

3.3 ERROR MESSAGES

Error messages associated with front panel operation are listed and explained in Table 3-4.

3-3

SECTION 3 Front Panel Operation

Table 3-4. Error Messages

DEFLTS UNCAL ROM ERROR

RAh4 ERROR TRG OVERUN

CAL VALUE CAL ERROR CALLOCK

CAL ZCHK INl?XRLOCK

Descriution Checksum error in default condi-

tion during power-up. Checksum emor in calibration during power-up. Failed ROM self-test. Failed RAM self-test.

Trigger overmn;

instrument trig-

gered while still processing a previol.Ls trigger. Calibration value conflicts with

the currently selected range.

Calibration value not within al-

lowable limits. Sent calibration command with

calibration switch (CAL LOCK) disabled.

Cannot calibrate pica-eter with zero check enabled. Tried to put V-Source in operate while an enabled safety interlock switch is open.

6. A displayed filter option is selected by pressing SHn;T and then FILTER SELECT (exits filter selection mode).

Voltage Source (Model 487)

The following basic rules to set the level of the voltage

source assume that the Model 487 is in the measurement display state. Refer to Figure 3-ZB for location of controls.

1. The cursor Cflashing digit) for the voltage source display is enabled when the rotary knob is turned, or when a 4 orb key is pressed.

2. The position of the cursor is controlled by the 4 and b keys. With the cursor on the most significant digit,

pressing 4 will select the 500V range. With the cursor on the least significant digit, pressing l will select the 50V range.

3. The rotary knob is used to adjust the voltage source

level.

3.4

DATA ENTRY; BASIC RULES

The following basic rules pertain to enttig data from

the front panel for MENU items, TRIGGER SETUPS, FILTER SELECTions and the voltage source (Model 4%‘). These rules, to some extent, s-&e the operation of

these features. The detailed information for using these features is found later in this section.

MENU, TRIGGER SETUP and FILTER SELECT

1. Menu and trigger setup items are displayed by simplypressingMENUorTGERSETUP. Indicators

denote the feature that is enabled.

2. Filter selections are displayed by pressing SHIFT and then FILTER SELECT in that order.

3. Options of the enabled feature are dii layed by us-

ing the rotary knob or 4 and

keys (see

Figure 324).

4. A displayed option of a menu item is selected by

pressing MENU.

5. A displayed option of a trigger setup is selected by

pressing SETUP.

Select option Of

displayed MENU, TRIGGER SETUP, or FILTER SELECT item

A. Menu. TRIGGER SETUP and FILTER SELECT

Figure 3-Z.

Data Entry

3-4

Front Panel Operation

SECTION3

3.5 CURRENT MEASUREMENTS

3.5.1 Current Ranges

VRANGEA

El El

AUTO

RANGE

Range selection provides control over the sensitivity of the measurement. The available current ranges of the Model 4&j/487 are listed in Table 3-5. Also included in the table for each range are mum input voltage overload.

Table 3-5. Current Ranges

2nA 219999nA

z&IA 21.9999nA

2ochA 219.999nA 35OVdc

2.19999pA 3SOVdc

lipA

2wA

21.9999pA 5OVdc

219.999&4 5OVdc

2.19999mA

wgiler voltages require current to be limited to

3mA.

maximum reading and maxi-

35OVdc 35OVdc

5OVdc

also be controlled automatically and is discussed in the

next paragraph.

3.5.2 Autorange

SHIFT

AUTO

RANGE

When autorange is enabled (AUTO RANGE indicator on), the instrument will automaticaliy go to the lowest possible (most sensitive) current range to make the measurement. Autorange is enabled by pressing SHIFT and then AUTO RANGE in that order. To disable autorange, again press SHIFT and then AUTO RANGE. Autorange will also disable by manually selecting a different range using the ‘I and A range keys.

CAUTION To avoid possible damage to the instnunent, do not apply more than 5OVdc to the input when autorange is enabled (unless an external series resistor to limit current to 3mA is used).

3.5.3 Zero Check and Correct

SHIFT

--..-

CHECK

q El

CORRECT

CALITION

Do not exceed the maximum input voltage as specified in Table 3-5. Otherwise, damage to

the Model 486/487 may result

NOTE After an overload occurs, it may take several minutes for the instrument to recover and display a settled reading. In general, the more severe the overload, the longer it take to re-

COVeI-.

Manual range selection is accomplished with the two ranging keys. Each press and release of the RANGE A key upranges the instrument to the next higher current

range. Conversely, RANGE v downranges the instrument to the next lower current range. Range selection can

When zero check is enabled, the input amplifier is internally discomected from the input connector of the in-

strument. A 1COkQ resistor shunts the input connector, and the instrument is configured to measure and display the offset of the selected range.

When zero correction is performed, the offset is measured and algebraicaLly subtracted from every subsequent reading Cmhding zero checked readings). This correction value is “remembered” and used until a new correction value is established by again performing zero correction. Also, an established correction value can be retained as a default condition on power up (see paragraph 3.8.6).

Zero check is enabled by pressing ZERO CHECK (ZERO

CHECK indicator turns on). Pressing ZERO CHECK a second time disables the feature.

3-5

SECTION 3 Front Panel Operation

when zero correction is performed, only the present range is zero corrected. Before making measurements, it is recommended that each current range be zero corrected. The zero corrected value for each range is “remembered”. The zero corrected values can be retained as default conditions on power up (see paragraph 3.8.6).

For best measurement accuracy, zero correction should

be performed any time a settled zero checked display is

not readingzero. Notethatzerocheckdoessnot havetobe enabled to perform zero correction. The instrument will automatically zero check the input before performing the correction.

Perform the following steps to perform zero correction:

1. Enable zero check and allow the displayed reading

to settle.

_ .

2. To perform zero correction, press SIGT and then CORRECT in that order. The following

message

will

be displayed while zero correction is in process:

CORRECl-ING

After correction, the instrument returns to the normal

measurement display state. Zero check will be on only if it was enabled in step 1.

Performing zero correction wiII cancel (zero) only the

measured offset.

Note: In the V/I ohms hmction, the ZERO CHECK indi-

cator will flash if zero check is enabled. In zero check, the displaywiUblsnk(-----KS&

3.54

Filters

SHIFT FILTER

FILTER

Filtering is used to stabilize noisy measurements. The Model 486/487 has two available filters; a digital filter and an analog filter. The digital filter is a function of measurement conversions. It bases the displayed (or stored) reading on the weighted average of a number of measurement conversions. The analog filter is a simple RC filter whose time constant varies with the selected range. It affects the rise time and settling time of the measurement (see Table 3-6). Rise times are defined as the time it takes the measurement to go from 10% to 90% of its final value of a step change. Settling time is the total time it takes the measurement to reach its final value (within 0.1%).

Enabling zero check with a REL baseline established (see paragraph 3.5.5) will remove the applied signal from the input with a displayed reading as follows:

Displayed reading = input signal-relative baseline

= 0 -relative baseline =-relative baseline

Table 3-6. Analog Filter Effects

;

56msec

17msec

6msec 2msec

When the filter is enabled, the selected filter(s) (digital filter, analog filter or both) will be used. Filter is enabled by simply pressing PILTER (FILTER indicator will turn on). PressingFILTERthesecondtimewilldisablethefilterk).

Perform the following steps to check or change the filter selection:

tbled

settling

Time

7Omsec

12msec

4msec 2msec

333msec

56msec 17msec

6msec 2msec

2OlStX

2msec

Front Panel Operation

SECTION 3

1. Press SHIFT and then FILTER SELECT in that order. One of the following

messages

will be displayed to

indicate the currently selected filter(s):

FILTER FILTER FILTER

DIGUAL ANALOG DIG+AN

(Digital filter selected) (Analog filter selected) (Both digital and ana-

log filters selected)

2. To select a different filter, use the rotary knob, or the 4 and b keys to display the desired filter selection.

3. Enter the displayed filter selection by pressing

Sm and then FILTER SELECT. The instrument will return to the normalmeasurement display state.

NOTES:

1. Typically, both filters should be used unless trying to

optimize speed.

2. Factory initialization selects both analog and digital

filters, and enables the filter feature.

3. The filter selection and operation (enabledidis-

abled) can be saved as the default condition (see paragraph 3.8.6).

4. When using the digital filter in a one-shot trigger mode, keep in mind that the first triggered conver-

sions will not represent settled readings. A number of reading conversions are necessary to acquire a settled reading for the digital filter. For this reason, the digital filter should typically not be used when using the one-shot trigger mode.

baseline is established for a measurement function, that stored level will be the same regardless of what range the Mode1486/487 is on For example, if 1pA is established as the baseline on the 2@ range, then the baseline will also be $A on the 20@, 200@ and 2mA ranges. A relative baseline level can be as large as full range. Selecting a range that cannot accommodate the baseline level will cause an overrange condition.

When a REL baseline level is established for current, the Rel’ed currentwillbeineffectwhenV/Iohmsisselec+ed (Model 487). This allows leakage current to be cancelled when performing V/I ohms measurements.

NOTE The following discussion on dynamic range is based on a display resolution of 5-l /2 digits. At 4-1/2d resolution, the number of counts would be reduced by a factor of 10.

By design, the dynamic measurement range of the Model 486/487, at 5-1/2d resolution, is 439,998 counts. With rel disabled, the displayed reading range of the instrument is ?219,999 counts. With rel enabled, the Model 486/487 has the capability to display &439,998 counts. This increased display range ensures that the dynamic measurement range of the instrument is not reduced when using a relative baseline value.

3.5.5 Rel

REL

The rel (relative) feature seTyes as a means of baseline suppression by allowing a stored offset value to be subtracted from subsequent readings. When rel is enabled, the ins!mment takes the currently displayed reading as a baseline value. All subsequent readings represent the difference between the applied signal level and the stored baseline.

A baseline level can be established for both current and V/I ohm measurements and is “remembered” by both functions. For example, a 1p.A baseline can be established for current measurements and a lOOa baseline can be es-

tablished for V/I ohms. These levels will not be canceled

by switching back and forth between functions. Once a

The following two examples will use the

maximum

allowable rel values (+219,999 counts and -219,999 counts) to show that the dynamic measurement range will not be reduced. It is important to realize that the increased display range does not increase the

maximum

allowable input level to the instrument. For example, on the 2mA range, the Model 486/487 will always overrange when more than z!z2.19999ti is connected to the input.

Example 1 -The insinunent is set to the 2mA range and a maximum -2.19999mA is established as the rel value. When -2.19999mA is connected to the input, the display will read O.OiXlOOmA. When +2.19999mA is applied to the input, the display will read +4.39998mA. Thus, the dynamic measurement range of the Model 486 is OmA to +4.39998mA, which is 439,998 counts.

Example 2 -The instrument is set to the 2mA range and

a maximum +2.19999ti is established as the rel value. When +2.19999mA is connected to the input, the display wilI read O.OOCOOmA. When-2.19999mA is applied to the

3-7

SECTION 3

Front Panel Operation

input, the display will read -4.39998mA. Thus, the dynamic

measurement range

of the Model 486 is OmA to

439998mA, which is still 439,998 counts.

Rel is enabled by pressing the REL key CREL indicator

hmw on). Pressing REL a second time disables the feature. The REL indicator (on or offl denotes the REL state of the displayed

measurement hrrent or

V/I ohms).

Perform the following steps to establish a relative baseline:

1. Disable rel, if presently enabled, by pressing REL. The REL indicator wilI turn off.

2. Selectacorrentrange orV/Iohmsrsnge(Mode1487) that is appropriate for the anticipated

3. Connect the desired baseline level to the

measurement.

input

of the

Model 486 /487. Model 486 /487.

4. 4. Press the REL key. The display will zero and the REL Press the REL key. The display will zero and the REL indicator will turn on. The previously displayed indicator will turn on. The previously displayed reading will be the stored level. reading will be the stored level.

NOTES:

connector that will mate to a cable terminated with a 3slot male triax connector. The center conductor of the connector is connected to input high, the inner shell is connected to input low, and the outer shell is connected to chassis ground.

CAUTION CAUTION To prevent damage to the Model 486/487, do To prevent damage to the Model 486/487, do not exceed the maximum input levels speci- not exceed the maximum input levels specified in Figure 3-3. fied in Figure 3-3.

Max Overload

2nA - 2W Range; 35OVdc

2OpA - Zm.4 Range: 50 “dc

.l. Enabling zero check with a rel baseline established

will remove the applied signal from the input with a displayed reading as follows:

Displayed reading = input signal-relative baseline

= 0 -relative baseline = -relative baseline

2. Disabling rel cancels the rel baseline value on that selected function. A baseline established on the other function is not affected.

3. To store a new baseline, rel must first be disabled and

then enabled again. the new value will be stored

with the first triggered conversion.

4. Setting the range lower than the suppressed value will overrange the display.

5. Enabling Rel while displaying dashes or an overranged condition will cause the RJZL indicator to blink until a valid on-scale reading becomes avail-

able. At that time, the REL indicator stops blinking (stays on) and the valid on-scale reading is used as

the Rel baseline value.

3.5.6

Current Measurements

Input Connector

Terminal identification for the Model 486/487 input connector is shown in Figure 3-3. It is a 3-lug female tiax

Trim Input Connector (3.Lug)

Current source connections to the Model 486/487 are shown in Figure 3-4 using the supplied triax-to-alligator cable. Note that if the current source is equipped with 3-lug triax female connector, a 3-slat t&.x-to-t&x cable (Model 707%TRX) could be used. A shield (connected to circuit low) should be used to minimize noise when making measurements below l@.

WARNING A shock hazard, that could cause severe injury or death, exists when the input signal is at 424V peak or more. When this voltage level is present, a safety shield

must

be used as shown in Figure 3-4. Chassis ground of the Model 486/487 must be connected to the safety shield. Also, a grounding wire (18 AWG or larger) must be attached securely to the safety shield at a screw terminal designed for safety grounding. The other end ofthegroundwiremustthenbeattachedtoa known safety earth ground.

3-a

Front Panel Operation

SECTION 3

CAUTION To prevent damage to the instrument, adhere to the following precautions when floating the input above chassis ground:

1. Do not connect ANALOG OUTPUT LO to CHASSIS. If there is a ground link installed at the rear panel binding posts, remote it.

2. Make sure that any monitoring imtrument connected to the analog output is floating.

Paragraph 3.16.8 explains the precautions for floating measurements in more detail.

Making Current Measurements Perform the following steps to make current measure-

ments:

1. Turn the instrument on, and allow the Model 486/487 towmupfortwo hours toobtainrated acCUK~Cy.

2. Make sure the instnunent is in the current function (amps reading displayed). If the V/I ohms function

of the Model 487 is selected kkns reading displayed), press SHIFT and then OHM!? to place the instrumat back in the current function.

3. Select a current range that is appropriate for the ex-

pected measurement or enable autorange (press SHIFT and then AUTO RANGE).

4. Enable zero check and, if the display is not zeroed,

perform zero correction by pressing SHIFT and then CORRECT.

Figure 3-4. Pi

3-9

SECTION 3 Front Panel Operation

5. Connect the current to be measured to the input of the Model 486/487 (see Figure 3-4).

6. Disable zero check and read the measured current on

the display of the Model 486/487.

Notes:

1. To prevent the possibility of oscillation, input low should typically be connected to a common low im-

pedance,suchas chassiioroutputlowifusingthevSource of the Model 487. Only use input cables that

are properly shielded and keep sible.

2. A number of other considerations that could have an affect on the integrity of current measurements are discussed in paragraph 3.16.

them

as short as pos-

3.6 USING THE VOLTAGE SOURCE (Model 487)

The V-Source of the Model 487 can source up to ?z505V at

2.5mA. The available voltage ranges of the V-Source are

summarizedinTable3-7. Thisis afloatingvoltagesource that is isolated from the chassis and signal common of the pica-eter of the Model 487. The output terminals &e-way binding posts) for the V-Source are shown in Figure 3-5. If desired, OUTPUT LO of the V-Source can be connected to chassis ground or signal common at the test fixhlre.

CAUTION The voltage sauce may fioat. However, neither V-Source terminal may ever be more than 5OOV above chassis.

Table 3-7. Model 487 V-Source

lock switch, such as the Keithley Model 8002A High Resistance Test Fixture. By using the interlock feature, the Model 487 cannot source voltage when the lid of the test fixture is open or ajar.

The interlock feature is automatically enabled when the supplied interlock cable (Model 236-ILC-3) is connected to the Model 487. When using Interlock with the Model 8002A test fixture, the voltage source of the Model 487 will go into standby whenever the lid of the fixture is open or ajar. Figure 3-6 shows the interlock of the Model 487 connected (and thus, enabled) to the Model 8002A test fixture.

WARNING Do not connect the interlock of a Model 487 to the interlock of another instrument. The interlock of the Model 487 is designed to be connected to a single-pole interlock switch of a test fixture. If connecting two or more Model 487s to a single test fixture, an isolated interlock switch for each instrument is required. Connecting multiple instxumant interlocks to the same switch could cause failure of the safety interlock system.

If using a custom-built test fixture, the following require ments must be met for safe operation:

Figure 3-5.

Model 487 V-Source Oufpuf Tennimls

3.6.1 Test Fixture and Interlock

The voltage source of the Model 487 is designed to be wed with a test fixture that incorporates a safety inter-

3-10

1. The metal chassis of the test fixture must be properly co~ected to a safety earth ground. A grounding wire(l8AWG orlarger)mustbeattachedsecurelyto

the test fixture at a screw terminal designed for safety grounding. The other end of the grmmd wire must then be attached to a known safety earth ground.

2. The test fixture must have a lid that closes toprevent contact with live circuitry inside. Safe operation re-

quires that a safety interlock switch be used to interrupt alI power sources when the lid of the test fixture is open or ajar. Information required to build an in-

terlock that will be compatible with the Model 487 is provided in Figure 3-7.

Interlock Cable ISUDDlied) 236ILC-3

F&ye 3-6. Interlock Connections

Front Panel Operation

SEC’UON 3

A Imerlock Connection 10 Test Sxture

c. l”wlclck co”“ectc.r:

Kelthley P/N : cs-659 (swnchcmfl PIN : TS3M)

,‘igure 3-7.

3.6.2

;-----T------,-----;

8. Pane, w,ovt dlmenslons

L------l-- ____ /__---I

Interlock Connections

Adjusting V-Source Level

The rotary knob and the 4 and b keys are used to adjust the V-Source level which is displayed just above the knob

(see Figure 3-8).

WARNING With the inshument in operate (OPERATE indicator on), the displayed voltage level (possibly hazardous) will be applied to the

0. merlock wmng

output terminals of the V-Source. The VSource should be kept in standby until ready to safely source voltage to a load.

With the Model 487 in the normal measurement display state, perform the following steps to adjust the level of the V-Source:

1. Press 4

orb to

enable the cursor.

3-11

SECTION 3 Front Panel Opemticm

Figure 3-8.

v-source Adjust

NOTE: For best accuracy, use the 5OV range to source

zk50.5v

or less.

Quick Zero

The Quick zero feature allows you to set the voltage source of the Model 487 to OV with two key presses; SHIFTand4or~key. Thevoltagesourcewillnot change ranges. For example, with the voltage source level currently set to 100.5OV (5OOV range), pressing SHIFT and the+ (or4 ) will set the voltage source to OV on the 500V range (OOO.OOv). To return to the previously set voltage source level, simply press SHIFT and w (or 4 ) again

The cursor is indicated by the flashing digit. Jf an adjust action does not occur in three seconds, the cursor will disable.

2. Select the appropriate v-source range.

The position of the decimal point in the displayed VSource reading denotes the selected range. For example, a reading of OO.OOOV is OV on the 50V range, while a reading of OCO.OOV is OV on the 500V range.

Ifonthe50Vrange,the500Vrangecanbeselectedby pressing 4 until the displayed range changes. Conversely, to select the 50V range, press b until the range change occurs.

3. Position the cursor on the digit to be adjusted.

The position of the cursor is controlled by the 4 and

b keys. Each press of the 4 key moves the cursor to

the next more significant digit. Each press of the b key, moves the cursor to the next less significant digit.

3.6.3

Preset

PRESET

OHMS

(VA)

preset allows the V-Source to be adjusted to a predetermined level at

the

touch of a single key. This feature eliminates the tedious task of manually adjusting the VSource to a frequently used level.

Perform the following steps to preset a V-Source level:

1. Enable preset by pressing PRESET. The PRESET indicator will turn on.

2. Adjust the V-Source to the desired range and level using the 4 and b keys, and rotary knob as previously explained.

3. Disable preset by again pressing PRESET. The volt;a;,;urce will return to the level it was previously

4. Adjust the voltage source 1eveL

The rotary knob is used to adjust the voltage source level. Turning the knob clockwise increases the voltage level at the cursor position, and conversely, toming it counter-clockwise decreases the voltage level.

Cursor position determines how much the displayed value changes with each detent turn of the knob. For example, with the cursor on the tenths digit of the displayed value, each detent turn of the knob will increase or decrease the value by 1 /lO volt (10omv).

3-12

Whenever preset is enabled, V-Source will adjust to the value set in step 2.

NOTES:

1. A preset V-Source level can be saved as the default condition (see paragraph 3.8.6).

2. A preset V-Source value of OO.COOV is the factory default condition.

3. With the V-Source in operate, the output will immediately update to whatever voltage value is displayed (unless I-limit occurs).

Front Panel Operation

SECTION 3

The Quick Zero feature can be used to set the Preset level to ov as foIlows:

1. Enable Preset by pressing PRESET.

2. Perform Quick Zero (press SHIFT and then, (or4 ).

3. Disable Preset by again pressing PRESET. The voltage source will return to the previously set level.

3.6.4

The V-Source has current limit (I-limit) capabilities to protect the instrument and external current sensitive cir-

cuitry from possible damage. The V-Source can be set for an I-limit of 25p.A or 2.51x4.

When I-limit occus, the OPERATE indicator wiIl flash. This indicates that the V-Source is no longer sourcing the programmed voltage level to the load. For example, assume the V-Source is set to source 1OV to a 25Ok!J load with I-limit set to 2Sfl. Based on Ohms Law, the current through the load should be 40@ (lOV/25OkQ = 4Ow). However, because the I-limit is set to 25&% the current through the load will be 25@. The actual voltage applied totheloadwillreally be625V (25OkQX25!.~A=6.25V)instead of the programmed 1OV. lf the 250k.Q load can handle 2.5mA without being damaged, then the I-limit could be increased to 2.5mA to prevent I-limit from occurring.

Perform the foIlowing steps to set I-limit:

I-Limit

3.6.5 Operate MO” 2mA

The OPERATE key toggles the output between standby and operate. In standby, the V-Source is removed from the rear panel output terminals. In operate (OPERATE indicator on) V-Source is applied to the output terminals.

A flashing OPERATE indicator denotes that the V-Source is in current limit as previously explained in paragraph

3.6.4.

CAUTION

A relay switch, in series with OUTPUT HI, is

opened when the V-SOURCE is placed in standby. The transition to an open output creates a potential for noise spikes. The open

output allows dielectric absorb&n to recharge capacitors to unexpected voltage levels.

3.6.6 Basic V-Source Operating Procedure

The following procedure will summarize how to use the V-Source as a separate, independent source. Using the VSource in conjunction with the pica-eter is covered in paragraph 3.7 (V/I ohms measurements) and paragraph

3.15 (Source V Measure I). This procedure assumes that

the user is familiar with the operation of the basic VSource controls as previously explained.

Keep pressing and releasing MENU until the GUIrently selected I-limit is displayed:

Use the rotary knob, or 4 and b keys to display the

desired I-limit value.

To,enter the displayed I-limit, press MENU. The next

menu item will be displayed.

To exit the menu, press SHIFT and then EXIT in that

order. The instrument will return to the normal measure display state.

Perform the following steps to use the V-Source:

With the V-Source in standby (OPERATE indicator off), connect the load to the V-Source output terminals as shown in Figure 3-9. Use the rotary knob, 4 and b the keys to set the de-

2. sired voltage range and level. Note that if previously set, a preset value can be used by enabling preset.

Select the appropriate I-limit (25@ or 2.5m.4).

Press OPERATE. The OPERATE indicator will turn on to denote that the displayed voltage level is available at the output terminals.

To disable the V-Source, again press OPERATE. The OPERATE indicator light will turn off.

3-13

SECTION 3

Front Panel Operation

Model 487

Figure 3-9. Basic V-Source Connections

3.7 V/I OHMS MEASUREMENTS (Model 487)

By using the V-Source in conjunction with its picoammeter, the Model 487 can make resistance measurements as high as 50.5 x lO”9.. With V/I ohms selected, the resis-

tance is automatically calculated from the applied voltage and measured Current (R = V/D and displayed (in ohms) on the Model 487. A& resolution of the resistance measurement depends on the s&&d current Rage.

The V/I ohms function is enabled by pressing SHIFT and then OHMS. The display will toggle to the resistance (.Q) measurement state. To disable V/I ohms, again press Sm and then OHMS. The display will return to the normal amps measurement state.

Perform the following steps to make V/I ohms measure mentsz

1. Turn on the Model 487 and allow it to warm up for two hours to achieve rated accuracy.

2. Disable the V/I ohms function, if it is currently selected.

3. With zero check enabled and the V-Source in standby, connect the circuit shown in Figure 3-10. The Keithley Model 8002A test fixture is shown because it is ideally suited for V/I ohms measurements of Z-terminal devices.

4. Select a current range that gives the nearest full scale reading or autorange, and perform zero correction by pressing SHBT and then CORRECT.

5. Set the V-Source to the desired voltage level.

6. Press OPERATE to tom on the source output, and disable zero check. The current measurement willbe displayed.

7. Enable V/I ohms by pressing Sm and then

OHMS. The resistance measurement will be displayed in ohms (Q).

8. To measure from a baseline resistance, enable rel

while in V/I ohms.

3-14

Front Panel Operation

SEClTON 3

L-----------’

Model 8002A

‘igure 3-10. V/l Ohms Connections (Source V Measure 1)

To make V/I ohms measurements, the Model 487 is configured to source voltage and measure current (Source V Measure I). The V/I feature simply performs the calculation (R = V/I) and displays the resistance reading in ohms. The results of any source V measure I test can be converted to resistance by using the V/I ohms function. Paragraph 3.15 expands on tests that source voltage and

measure

current, and provides some examples that are

particularly applicable to the V/I ohms function.

CAUTION

To prevent damage to the instrument, ad-

here to the following precautions when floating the input above chassis ground:

1. Do not connect ANALOG OUTPUT LO to CHASSIS. If there is a ground lii installed at the rear panel binding posts, re-

move it. 2 Make sure that any monitoring ins&w ment connected to the analog output is float-

tng. Paragraph 3.16.8 explains the precautions for

floating measurements in more detail.

3-15

SECTION 3 Front Panel Operation

NOTES:

Do not use zero check while in V/I ohms. Doing so will blank the display (i.e. ” KU’) and cause the ZERO CHECK indicator to flash. Placing the V-Source in standby while in V/I ohms

2. will result with zeroes being displayed (i.e.

I6-U.

The minus (-1 sign is not disabled in V/I ohms. Po-

3. larity changes during a test could indicate charge/ discharge effects of the DUT. For example, a DUT may behave as a capacitor. At a certain voltage the capacitor will charge and display some positive resistance reading. If the V-Source is decreased, the capa&or will discharge causing current to flow in the opposite direction. A negative resistance reading

will then be displayed.

If a current Rel baseline exists (REL indicator on while displaying current measurements) when V/I Ohms is selected, resistance is calculated as follows:

0.00000

R=&

where: I is the actual current.

IO is the current rel baseline level.

Optimiziig Accuracy

When using V/I ohms, the V-Source range and current range should be set up to optimize accuracy. In most

cases, it is best to use the maximum voltage possible and set the current range accordingly. The instrument should

be placed in the most sensitive range possible without

causing an overranged condition. Doing so will optimize the measuement for resolution and accuracy. Autoranging can facilitate range selection.

ing material (such as Teflon@) for terminal connections in custom-built test fixtures.

The current Rel feature provides a way to compensate for leakage resistance which cannot be eliminated from the test fixture. If the DUT (device under test) is removed from the test fixtwe and then the test voltage is applied to the fixture, the resulting Current will be entirely due to

the leakage resistance. Using Rel (while in the current function) will “eliminate” this leakage current. Then with the DUT in the test fixture, the current used for the V/I

ohms calculation will be entirely due to the DUT.

NOTE Paragraph 3.16 contains additional considerations that must be addressed when making current measurements.

3.8 MENU

The menu items are listed in Table 3-8. In general, each press of the MENLJ key displays a menu item in the order shown in the table. The available selections of the displayed menu item are selected and displayed with the ro-

tary knob or the4 and b keys. The selected option of the displayed menu item is entered by again pressing

MENU. To exit the menu, press SHIFT and then EXIT.

The following information wiIl provide the detailed

steps for selecting the available options of the menu item program.

3.8.1 Data Store

V/I ohms measurements tend to be more accurate when current measured is close to full scale. Disadvantages of operating with higher voltages include power dissipa-

tion in the DUT and voltage coefficient of high impedance DUT.

Leakage Resistance There ,are cases where leakage resistance could adversely

affect V/I ohms measurements. For example, test fixture leakage paths may appear in parallel with the device being measured, introducing errors into the measurement. These errors can be minimized by using proper insulat-

3-16

This menu item is used to arm the data store and select the number of readings to store in the buffer. Details for using the data store is contained in paragraph 3.11.

Data Store Selections:

NO Do nothing YES Arm data store BUl%ERSIZE

BUFFERSIZE 001512 RDGS Number of

ODD RDGS

Wraparound operation (circular buffer)

readings to

store in buffer

Front Panel Opration

SECTION 3

Table 3-8.

Menu Item Description DATA STORE

DATA RFXL nlMrr

INTEGRATE IEEE-488 DEFAULTS

SELETEST DEBUG CALIBRATE CAL v SRC

Perform the following steps to arm the data store and set buffer size:

1. Press and release MENU until the folkxving message is displayed:

DATA STORE NO

NO indicates that the data store is not armed. If you are not going to store readings, exit the menu by pressing SHIFT and then EXlT.

2. Use the rotary knob or the 4 and b keys to display the following message:

DATASTORE YES

Arm data store and set buffer size Recall data stored in buffer Set current limit; 25yA or 2.5mA (Model 487 only)

Set integration period; fast or line

cycle (50 or 6OHz) Set IEEE-488 address O-30 or select Talk-only Save steps as power-up defaults, rehxn to previously saved defaults, or return to factory defaults Test display and memory elements Troubleshooting mode Calibrate current range Calibrate V-Source (Model 487 only)

MENU Items

5. With the desired buffer size value displayed, press MENU. The instrument will exit the menu and wait for a tigger to start the storage process as shown in the following example:

-.-----d”

The I’*” indicates that tlw data store is armed, and the flashing TRIGGER indicator denotes that the ins!zrument is waiting for a trigger.

NOTE: when setting buffer size, you cannot increase a selected digit that will cause the value to exceed 512. For example, if the present value is 428 with the cursor on the

“4”, you cannot increase it to a “5” since 528 is invalid. To increment the value 428, the cursor must be on the “2” or the ‘8”.

3.8.2

This menu item is used to recall data that is stored in the buffer using the data store. Details for using the data store is contained in paragraph 3.11.

Data Recall Selections:

Data Recall

NO YES LOC 001-512

LOCMIN LOCMAX

Disable data recall Enable data recall Stored reading at displayed buffer location Minimum reading stored in buffer Maximum reading stored in buffer

3. To arm the data store, press MENU. T’ne following message will appear on the large display:

BIJFFERSIZE

On the small display, the last progmmmed size value will be displayed.

4. Use the ADJUST controls to display the desired value. The 4 and b keys position the cursor on the digit to be adjusted and the rotary knob increments or decrements the value from the selected digit. For example, to store 236 readings in the buffer, adjust the value to the following display message:

BUFFERSIZE 236 RDGS

Perform tlw following steps to recall data stored in the data store buffer:

1. Press and release MENU until the following message is displayed:

DATA RECL

NO indicates that data recall is disabled. If you do not wish to examine stored readings, proceed to step

2. Use the rotary knob or the 4 and b keys to display the following message:

DATA RECL

YES

3-17

SECTION 3 Front Panel Operation

Press MENU. The stored reading at memory location 001 will be displayed. For example, if the stored reading is -l.OOOOOmA, the following will be displayed:

-1.00000 rd.

LOC 001

The stored readings at the other memory locations

(and MIN and MAX) can be examined by using the ADJUST controls. The4 and b keys position the cursor on the digit to be adjusted and the rotary knob increments or decrements the memory location nunher from the selected digit. Decrementlng the value from 001 displays the maximum and minimum readings. To exit from data recall press MENU to display the next menu item, or press SHIFI and then EXIT to exit from the menu.

NOTES:

1. The message “NO DATA” on the small display, indicates that there are no readings stored in the buffer.

2. Turning off power, performing factory initialization, defaultsrecallorsendinga DCLorSDC overthebw, clears the buffer (NO DATA).

3.8.3

I-Limit (Model 487)

3. Enter the displayed I-limit by pressing MENU. The next menu item will be displayed.

4. To exit from the menu, press SHIFT and then EXIT. The instrument will return to the normal measurement display state.

3.8.4 Integration

This menu selection is used to check or change the integration period for A/D conversions.

Integration Period Selections:

FAST LINE6OHZ LINE5OI-u

The selectable integration periods offer a trade-off between speed, resolution and noise rejection. The fast integration period provides the fastest measuements and should be used when speed is the most important consideration. The line cycle integration periods provide slower but more stable (quieter) measurements by rejecting power line noise. To achieve the most stable measurements, select the line cycle period that matches the available line frequency.

1.6msec integration (4-l /2 digit resolution) Line cycle 06.67msec) integration (5-l/2 digit resolution) Line cycle (20msec) integration (5-l /Z,digit resolution)

This menu item is used to check or change the current limit setting of the V-Source of the Model 487. Details on I-limit is contained in paragraph 3.6.4.

I-Limit Selections:

2.5mA I-limit setting of 2.51~4 25~

I-limit setting of 25+4

Perform the following steps to check or change the Ihit:

Press and release MENU until the currently selected I-limit is displayed. For example, if I-limit is 25pA, the following message will be displayed:

ILmm-

2-w.

To retain this I-limit setting, proceed to step 3 or 4.

Use the rotary knob or the 4 and b keys to display the alternate I-limit.

Perform the following steps to check or change the in& gration period:

Press and release MENU until the currently selected integration period is displayed. For example, if the integrationperiodiscurrentlysetfor60Hzlinecycle, the following message will be displayed:

JNTEGRATE

LINEXOHZ

To retain this integration period, proceed to step 3 or

Use the rotary knob or the 4 and fi keys to display the desired integration period.

Enter the displayed integration period by pressing MENU. The next menu item will be displayed.

To exit the menu, press SHIFI and then EXIT. The instrumentwill return to the normal measurement display state.

NOTE: Menu selection DEFAULT SAVE (see paragraph

3.8.6) can be used to save the selected integration period as the power-up default condition.

3-18

Front Panel Operation

SECTION 3

3.8.5

This menu item is used to check or change the IEEE-488 address, or select talk-only.

IEEE-488 Selections:

At the factory, the IEEE-488 address is set to 22. However, it can be set to any valid value from 0 to 30. Section 4 contains detailed information on IEEE-488 programming. In talk-only, the instrument will continually output data to a listening device, such as a listen-only printer. Details on using talk-only are contained in paragraph 3.13.

Perform the following steps to chedc or change the IEEE-488 address, or select talk-only:

Press and release MENU until the current IEEE-488 selection is displayed. For example, if primary address 22 is currently selected, the following message will be displayed:

To retain this selection, proceed to step 3 or 4.

IEEE-488 Address or Talk-Only

ADDR 00-30

TALKONLY

IEEE-488

IEEE-488 primary address talk-only mode

ADORE!

Default Selections:

OK Do nothing SAVE

RECALL Retun to previously saved powerFACTORY Return to factory default conditions

Perform the following steps to use a default selection:

Press and release MENU until the following mes-

1. sage is displayed:

DEFAULTS

If you do not wish to execute one of the other default selections, proceed to step 3 or 4.

Use the rotary knob or the 4 and W keys to display

the desired default selection.

Execute the displayed default selection by pressing

3. ENTER. If “OK” or “SAW” is executed, the next menu item will be displayed. If “RECALL” or “FAC-

TORY” is executed, the instrument will return to the normal measurement display state. If still in the menu, you can exit from it by pressing

4. SHIFT and then EXIT.

Save present operating states as power-up default conditions

up default conditions and save as power-up default con-

ditions.

Use the rotary knob or the 4 and F keys to display the desired address or talk-only. Enter the displayed selection by pressing MENU.

3. The next menu item will be displayed.

To exit the menu, press SHm and then FXIT. The instrument will return to the normal measurement display state.

NOTE The instrument will power-up to the last selected

IEEE-488 selection.

3.8.6 Defaults

This menu item allows you to save the present operating states as the power-up default conditions, or to return the instrument to previously saved default conditions, or to return the instrument to the factory default conditions. Factory default conditions are listed in Table 3-3. Also in-

dicated in the table are the controls/features that can be

saved as the power-up default conditions.

3.8.7

This menu item is used to test display segments and in-

ternal memory elements. During the display test, each segment of all the LEDs will be briefly displayed. Then,

all segments of each LED will be sequentially displayed. The display test takes approximately 17 seconds to complete. After the display test, tests on its memory elements will be performed.

Self-Test Selections:

Perform the following steps to perform the self-test:

1. Press and release MENU until the following mes-

Self-Test

NO YES

sage is displayed:

SELFlXST

Do not perform self-test Perform self-test

3-19

SECTlON 3

Front Panel Operation

lfyoudonottishtoruntheself-test,proceedtostep

Use the rotary knob or the 4 and b keys to display the folkwing message:

SELFTEST YES

To run the test press MENU. After the display test is

completed, tests on its memory elements will be per-

formed while the following message is displayed:

SELFJXST

Tests on its memory elements takes approximately five seconds. If the tests pass, the next menu item will be displayed. In the event of a failure, one of the following messages will displayed.

ROM ERROR RAM ERROR

The error message can be canceled by pressing any front panel key. However, a problem existsand must be resolved. Refer to the troubleshooting informa-

tion in

To exit from the menu, press SHIFT and then FXT. The instrument will return to the normal measurement display state.

3.8.8

The debug menu item locks the A/D converter in one of

three multiplexer state to allow signal tracing through the inswument during troubleshooting. Refer to paragraph 7.7 for details on using this feature.

Section 7.

Debug

3.9 FRONT PANEL TRIGGERING

TRIGGER

SETUP

TRIGGER

The following paragraphs discuss front panel triggering, trigger mode selection, trigger interval, trigger delay and trigger source.

3.9.1

The Model 486/487 may be operated in two basic trigger

modes; one-shot

separate trigger is required to initiate each reading. For the multiple mode, however, only a single trigger is required, with conversion rate determined by the pro-

grammed trigger interval. The multiple trigger mode is the factory default, however, the one-shot mode can be saved (see paragraph 3.8.6) as the power-up default.

To check or change the selected trigger mode, proceed as follows:

Trigger Mode

and multiple. In the one-shot mode, a

Ifyoubaveinadvertentlyselected debug,pressMENU to display the next menu item, or press S-IIFT and then EXIT to exit the menu.

3.8.9

The calibrate program is used ~to calibrate the current ranges of the Models 486 and 487. Refer to paragraph 7.3

to calibrate the instrument.

3.8.1.0

This program is used to calibrate the V-Source of the Model 487. Refer to paragraph 7.3 to calibrate the VSource.

3-20

Calibrate

Cal V SRC (Model 487)

Press SETUP to enable trigger setup (SETUP indicator turns on). The currently selected trigger mode will be displayed. For the multiple mode, the following will be displayed:

TRIG MODE

For the oneshot mode, the following will be dis played:

TRIG MODE

To toggle the displayed trigger mode use the rotary knob or the 4 and b keys.

Select the displayed trigger mode by pressing SETUP to display the next trigger setup selection

(trigger interval), or by pressing SHIFT and then

SETUP to exit trigger &up.

MULTIPLE

ONE-SHOT

Front Panel @eration

SECTION 3

3.9.2

The trigger interval determines the time period between individual readings when the instrument is in the multi-

ple trigger mode. Interval also affects the storage rate of

the data store.

The trigger interval can be set from ZOmsec to 999.999sec.

A trigger interval of 175msec is the factory default condition. However, any valid trigger interval can be saved (see paragraph 3.8.6) as the power-up default.

Trigger interval speeds from 1Omsec to 49msec can only be achieved using the data store. Otherwise, an interval

of 5Omsec or the programmed interval (whichever is

greater) will be used.

Perform the following steps to check or change the selected trigger interval:

Trigger Interval

NOTE Trigger interval cannot be set in the one-shot trigger mode.

conversion, with the instrument waiting the programmed delay time after each trigger before taking a reading. For example, if you program a 3OOmsec trigger delay, the unit will wait 3L%nsec after each trigger before taking a reading.

TheMode1486/487canbeprogranunedforadelayintervalfromOsecto999.999secin Ims&.ncremenk. A trigger delay of Osec is the factory default; however, any valid trigger interval can be saved (see paragraph 3.8.6) as the power-up default.

NOTE If a trigger occurs during the trigger delay pexiod. the txizzer overrun (TRG OVERUN) error &ssag~%ll be displa&d. The tigger that caused the error will be ignored.

Perform the following steps to check or change the trigger delay period:

Press and release SJZTUP until the trigger delay is displayed. For example, if the trigger delay is set for Osec (factory default), the following will be displayed:

Press and release SETUP until the trigger interval is displayed. For example, if the trigger interval is set for 175msec (factory default), the following will be displayed:

TlUGINTVL 000.17~

To retain the displayed trigger interval, proceed to step 3.

Use the4 and b keys, and the rotary knob to display the desired value. The4 and, keys position the cursor on the digit to be modified, and the rotary knob increments/decrements the value from the selected digit. Select the displayed trigger interval by pressing SETUP to display the next trigger setup selection

(trigger delay), or by pressing SHIFT and then

SETUP to exit trigger setup.

3.9.3

Trigger delay is the time from the trigger point until the unit takes a readiig. In the multiple trigger mode, the delay period affects only the first conversion; however, in

the one-shot bigger mode, the delay period affects every

Trigger Delay

TRIG DELAY 000.~0

To retain the displayed trigger delay, proceed to step

Use the4 and, keys, and the rotary knob to display the desired value. The4 and, keys position the cursor on the digit to be modified, and the rotary knob

increments/decrements the value from the selected

digit.

select the displayed bigger delay by pressing

SETUP to disc&w the next tieeer setup selection

bigger sourch’or by pressi;;gu SHE+ and then SETUP to exit trigger setup.

3.9.4 Trigger Sources

For front panel operation, there are three trigger sources

available; front panel TRIGGER key, the EXTERNAL

TRIGGER INPUT jack, and the OPERATE key for the V-

Source of the Model 487.

With the external trigger source selected, a trigger pulse applied to the rear panel EXTERNAL TRIGGER INPUT jack will trigger the insbunent (see paragraph 3.10.1 for

3-21

SECTION 3 Front Panel Operation

details). With the operate trigger source selected, a trigger will occur when the V-Source of the Model 487 is placed in operate. The front panel TRIGGER key is always enabled, regardless of the selected trigger source; however, this key is locked out when the instrument is in remote.

Additional trigger sources include IEEE-488 X, GET, and talk commands, as discussed in section 4.

The external bigger source is the factory default; however, any of the other trigger sources can be saved (see paragraph 3.8.6) as the power-up default condition

Perform the following steps to check or change the trigger source:

Press and release SETUP until the currently selected bigger source is displayed. If external trigger source is selected, the following will be displayed:

TRIG SRC

-AL

The other available trigger source selections:

TRIG SRC OPERATE TRIG SRC

BUS X

TRIGSRC GET TRIG SRC

TALK

TRIG MODE MULTIPLE

Press SETUP and use the 4 and b keys, and rotary knob to set a trigger interval of three seconds as follows:

TRIG

lNTE 003.000

Press SHIiT and then SETUP. The instrument will return to the normal measurement display state. The display will update with a new reading every three seconds as indicated by the trigger status LED (flashing decimal point) that follows the reading.

Example 2:

One-shot trigger mode with a one second trigger delay:

Press SETUP (SETUP indicator turns on) and use the rotary knob (if necessary) to display the one-shot trigger mode as follows:

TRIG MODE

Press SETUP and use the 4 and b keys, and rotary

ONE-SHOT

knob to set a trigger delay of one second as follows:

TRIG DELAY WI.OW

To retain the displayed trigger delay, proceed to step

Use the 4 and b keys, or the rotary knob to display the desired trigger source.

Select the displayed trigger source selection by pressing SETUP’. The instrument will return to the normal measurement display state.

3.9.5

Trigger Examples

Example 1: Multiple trigger mode with a three second interval be-

tween readings:

1. Press SETUP (SETUP indicator turns on) and use the rotary knob (if necessary) to display the multiple

trigger mode as follows:

3-22

Press SHIFl- and then SETUP. The instrument will return to the normal measuremfzit display state.

To initiate a single reading, press TRIGGER. Note that the display updates after a delay of approximately one second.

Quickly press TRIGGER twice. The second press of TRIGGER causes a trigger ov- error. The

mes-

sage “TRG OVERLJN” is displayed. The invalid trigger, which occurred during the delay period, is ig-

I-LOEXi.

3.10 EXTERNAL TRIGGERING

The Model 486/487 has two external BNC connectors on

the *ear panel associated with instrument triggering (see

Figure 3-11). The EXTERNAL TRIGGER INPUT comw-

tor allows the instrument to be triggered by other devices,whiletheMETERCOMPLETE OUTl’UTcom~ector allows the instrument to trigger other devices

Figure 3-11. Trigger Connectors

3.10.1 External Trigger

The external trigger input requires a falling edge pulse at TI’L logic levels, as shown in Figure 512. Connections to the rear panel EXTERNAL TRIGGER INPUT jack should be made with a standard BNC connector. If the in&ument is in theexternal higgersourcemode, itwillbe triggered to take readings while in either a multiple or oneshot trigger mode when the negative-going edge of the external trigger pulse occurs.

Front Panel Operation

SECTION 3

3.10.2 Meter Complete

The Model 486/487 has an available output pulse that

can be used to trigger other instrumentation. A single Tn-compatible negative-going pulse (see Figure 3-13) will appear at the METER COMPLETE OUTPUT jack each time the instrument completes a reading. To use ter complete output, proceed as follows:

1. Connect the Model 486/487 to the instrument to be triggered with a suitable shielded cable. Use a standard BNC connector to make the connection to the Model 486/487.

2. Configure the Model 486/487 to make the desired measurements.

3. In the multiple trigger mode, the instrument will output pulses at the conversion rate; each pulse wiLl occur after the Model 486/487 has completed a conversion.

4. Intbeone-shottriggermode,theMode1486/487wiU output a pulse once each time it completes a reading after being triggered.

me-

, .Qure 3-72. Extend Trigger Pulse Specific&ions

To use the external trigger, proceed as follows:

1. Connect the external trigger source to the rear panel BNC EXTERNAL TRIGGER INKIT connector. The

outer shell (shield) of the connector to digital com-

mon

2. Place the instrument in “one-shot on external triggei’ or “multiple on external trigger” as explained in

paragraph 3.9.

3. To trigger the instrument, apply a pulse to the external trigger input. The instrument will process a single reading each the the pulse is applied (one-shot), or start multiple readings.

NOTE

Triggering the unit while it is processing a

reading

from

a previous trigger will cause a

trigger overrun (TRG OVERUN).

LSTTLLOW 1 1

fO.25V Tvoical) I I

Figure 3-13. Meter Complete Specifimfions

3.11 DATA STORE

The data store can store up to 512 readings for later recall. Data can be stored at specific intervals of between 1Omsec and 999.999sec with lmsec increments. In addition, oneshot extemalorfrontpaneltriggeringcanbeused tostore data at arbitrary points in time.

The following paragraphs describe front panel operating procedures for stoxing and recalling data.

3.11.1 Storing Data at Programmed Intervals

Use the following procedure for storing data at defined intervals:

3-23

SECTlON 3 Front Panel Operation

Select function (amps or V/I ohms) and range to be used to

make

measurements. Autorange may be

- .

used. Set the trigger mode, interval and delay as follows:

Press SETUP and verify that the multiple trigger

mode is selected as follows:

TRIGMODE ~~JLTIPLE

If necessary, use the rotary knob or the 4 and b keys to display the multiple trigger mode.

Press SETUP and use the rotary knob or the 4 and b keys to display the desired trigger (storage) interval. For example, the following message denotes a trigger interval of l/2 second:

TRlG

INTVL 000.500

Press SETUP and use the rotary knob or the4 or

b keys to display the desired trigger delay. If you do not wish to delay the initial trigger that starts the storage process, set trigger delay to Osec as shown:

ning at the first memory location, overwriting the previously stored data.

Use the rotary knob or the 4 and b keys to display the desired buffer size value.

Enter the data store parameters by pressing MENU. The instrument will exit the menu and will wait for a trigger to start the storage process as shown in the following example:

-.-----tie

The “*” indicates that the data store is armed and is waiting for a trigger as denoted by the flashing TRIGGER indicator.

Press TRIGGER to initiate storage. The instrument will begin storing data at the programmed interval. While storage is active, you can be@n to examine

stored readings by entering the data recall mode (see paragraph 3.11.3).

After all readings have been stored, the displayed

“v’ wiIl turn off to indicate that the storage process has been completed (except for continuous wraparound storage).

TRIG DELAY

Exit trigger setup by pressing SHIFI and then

oo0.000

SETUP.

Arm the data store

and

set the buffer size as follows:

NOTE

Details on arming the data store and entering

buffer size parameters are contained in para-

graph 3.8.1.

Press and release MENU until the data store is selected, and use the rotary knob or the4 and k keys to display the following

DATA STORE

Press MENU. The currently defined buffer size

YES

message:

will be displayed. For example, if the buffer size is currently set for 100 readings, the following

message

will be displayed:

BUFFFRSIZ 100 RDGS

Note:Thesizevaluedetermineshowmanyreadings wi!J be stored (up to 512) before the storage cycle stops. However, a buffer size of 000 indicates that the storage cycle will conhue even after all 512 readings are stored. After the 512th reading is stored, readings will be stored begin-

NOTES:

The data store can be disarmed, even after the storage process has started, by changing a trigger setup; trigger mode, trigger interval, trigger delay or trigger source. Data storage can also be aborted by rearming the data store. The displayed “w’ turns off when the data store is disarmed.

Arming the data store clears the buffer of previously stored readings.

With the operate trigger source selected (see paragraph 3.9.4), placing the V-Source of the Model 487 inoperatewilltrigger thestartof thestorageprocess.

The front panel TRIGGER key can be used to start the storage process with any trigger source selected (see paragraph 3.9.4).

3.11.2 Triggering One-shot Readings into Data Store

Reading storage can be controlled by bigger pulses applied to the rear panel EXTERNAL TRIGGER INMIT (paragraph 3.10), by using the front panel TRIGGER key, or by placing the V-Source of the Model 487 in operate. In a one-shot trigger mode, each trigger stimulus will process and store a single reading.

For one-shot operation, the data store is configured the

same

as for multiple trigger operation as explained in the

3-24

previous paragraph. Only the trigger setup is different. The trigger mode is set for one-shot (TRIG MODE ONESHOT), and the trigger source is set for external U’RG

SCR EXTERNAL) or operate U-RG SRC OPERATE).

In the one-shot mode, each press of the TRIGGER key will cause a single reading to be processed and stored in

thebuffer.ThefTontpanelTRIGGERkeyisactiveregardless of the trigger source sekxiion. With the external big-

ger source selected (TRIG SRC EXTERNAL), each trigger pulse applied to the unit (see paragraph 3.9.4) will process and store a single reading. With the operate trigger source selected (TRIG SRC OPERATE), a single reading will be processed and stored each time the Model 487 VSource is placed in operate.

NOTES:

Front Panel Operation

To access a reading at a particular memory location, use the4 and, keys to position the cursor on the desired digit and use the rotary knob to adjust the location value from the selected digit.

exit

data recall, press SHIFT and then EXIT.

NOTES:

1. If the data store has no valid data to display, the following message will appear in the small display upon entry into data recall:

NO DATA

2. The instrument will continue to store data while in data recall until the data store buffer is full (unless in wrap-around operation).

SECI’ION3

Trigger interval cannot be set when in the one-shot

trigger mode.

Triggerdelay can besetintheoneshottriggermode. Each time the trig@r stimuh.~~ occurs, the reading and storageprocesswillnot occuruntilthedelayha expired.Anytriggersthatoccurduringthedelayperiod will result in a trigger overrun error URG OVERUS. The invalid trigger(s) will be ignored.

3.11.3 Recalling Data

Data can be recalled either during storage or after storage is complete by using the following procedure:

Press and release MENUuntil data recall is selected, and use the rotary knob or the <and> keys to display the following message:

DATARECL YES

PressMENUThereadingstoredinthefirstmemory location will be displayed. For example, if a 1mA

reading is stored in location 001, the following mes-

sage will be displayedz

1.ooom mA Lot 001

For sequential access, use the rotary knob. Turning the knob cow.ter-&xkwise will display the maximum (LOC MAX) and minimum readings stored in

thebuffer.Turrdngtherotaryknob clockwisewillincrement buffer locations until the last buffer location

is reached.

3.12 ANALOG OUTPUT

The Model 486/487 has a non-inverting ZV analog output. ANALOG OUTPUT connections are shown in Figure 3-14. For a ZOO,CPXI count input, the analog output will be ZV. Typical examples are shown in Table 3-9.

The output resistance of the analog output is lOOR. To minimize the effects of loading, the input impedance of the device connected to ANALOG OUTPUT should be as high as possible. For example, for a device with an input impedance of IOkQ, the error due to loading will be approximately 1%. Rel has no effect on the analog output. A

1mA input (2mA range) will result in a 1v analog output

whether Rel is enabled or not.

CAUTION To prevent damage to the imtmnent, adhere to the following precautions when floating the input above chassis ground:

1. Do not connect ANALOG OUTPUT LO to CHASSIS. If there is a ground link installed at the rear panel binding posts, remove it. 2 Make sure that any monitoring ins&ument connected to the analog output is float-

Paragraph 3.16.8 explains the precautions for floating measurements in more detail.

3-25

SECTION3

Front Panel Operation

L----------J

Equivalent Circuit

Meas”ri”g Device (Rr)

(i.e. Ghan Recorder)

?gure 3-14. Typical Analog Output Connections

Table 3-9.

Typical Analog Output Values

3-26

Front Panel Operation

SECTION 3

3.13 TALK-ONLY

In talk-only, the Mode1486/487 will talk continuously on the IEEE-488 bus and output readings to a listen-only device whenever a measurement conversion occurs. For example, in talk-only, measurement readings Model 486/487 will be tiansmitted to a listen-only printer that is connected to the IEEE-488 bus. Bus connections are covered in paragraph 4.4 of Section 4. While using talk-only, a controller cannot be connected to the IEEE-488 bus.

The listen-only device will not slow down the Model 486/487 measurement rate. For example, after the buffer of a listen-only printer fills, the printer will only accept readings

from

the Model 486/487 at its print rate. The Model 486/487 continues to take readings at its programmed rate, but sends them only as fast as the printer can accept them.

Perform the following steps to place the Model 486/487 in talk-only:

Press and release MENU until the present IEEE488 selection is displayed. For example, if the IEEE-488 busaddressissetto22, thefollowingmessagewillbe displayed:

IEEE-488

Use the rotary knob, or the W button to display talk-

ADDR 2.2

only a.5 follows:

from

the

3.14 OPERATING EXAMPLES

3.14.1 Measuring Current Generated by an LED

A standard light emitting diode (LED) will generate

small currents (nanoampere region) when exposed to

light. This operating example will use the Model 486 or 487 to measure the current generated by an LED over a range of light intensity, and store the readings in the data

store.

Equipment needed:

1 LED

1 Model 237-ALG-2 Alligator Cable (supplied)

Procedure:

NOTE Step 1 will return the instrument to factory default conditions. In that state, filter will be enabled (DIG+AN), zero check will be enabled, and autorange wilI be enabled.

Perform the following steps to perform factory initialization: A. Press and release MENU until the following

message is displayed:

DEFAULTS

IEEE-488

To enter the talk-only mode, press MENU. The

TALKONLY

TALK indicator will turn on.

Exit the menu by pressing SHIFI and then EXIT. The instrument will return to the normal measurement display state. Each measurement conversion will be sent over the bus.

NOTE: If the reading source is currently set to Bl (data store readings)

from

previous IEEE-488 operation (see paragraph 4.2.2 in Section 4), a data store dump to a listen-only device can be performed by placing the instrument in talk-only. If the instrument is in talk-only while data storage is in progress, each reading will be sent to the listen-only device at the programmed interval. If the instrument is placed in talk-only after the data storage is complete, all the stored readings will be sent to the listen-

only device as fast as it will accept

them.

B. Use the rotary knob to display the following

message:

DEFAULTS

FACTORY

C. Press MENU to perform factory initialization.

Connect the LED to the Model 486/487 as shown in Figure 3-15.

Zero correct the Model 486/487 by pressing SHIFT

and then CORRECT. Place the LED, with the test cable connected to it, in a

4. dark place (i.e. desk drawer, or a in a box).

Disable ZERO CHECK.

Verify that the reading on the display is around 1 pA or less. The LED should generate virtually OA in a daik environment.

Configure the data store of the Model 486/487 as follows:

A. Press and release SETUP until the trigger inter-

val is displayed. Use the 4 and b keys, and the

3-27

SECTION 3 Front Panel Operation

rotary knob to display an interval of l/2 seconds as follows:

TRIG

INTVL 000.500

Enter the displayed trigger interval by pressing

SHET and then SETUP. Press hD3VU and use the rotary knob to display

the following message:

DATASTORE YES

Press MENU and use the&md, keys to display

a buffer size of 50 readings as shown:

BUFFERSIZE

Arm the data store by pressing MENU. The

0.50~0~s

“data store armed” indicator (9 wilI be dis-

played.

NOTE When triggered, the data store will store 50 readings at an interval rate of l/2 seconds. This will give you approximately 25 seconds to move the LED gradually from the dark environment to a bright light sowce (lamp or flashlight).

11. Perform the following steps to recall stored data: A. Press and release MENU until the following

message is displayed:

DATARJXL

5. Use the rotary knob to display the following message:

DATARECL Y?Z?

C. Press MENU. The first reading (at memory loca-

tion 001) will be displayed. Since this measurement was performed in the dark, the following reading could result:

0.00074 Illi Lot 001

D. Examine the readings stored in the other mem-

ory locations by using the rotary knob. Turning

the knob clockwise increments the memory locations. Turning the knob counter-clockwise past location 001 displays the minimum and maximum readings stored in the buffer. For this test, the following

maximum and minimun readings

could result

022.106 nA

-0.36250 nA LOClV5V

LCChJAX

To start the data storage process, press the flashing TRIGGER kev.

After allowing a few seconds to acquire readings in the dark environment, gradually move the LED fromthedarktowardsabrightlightsouxe.Timethe transition from dark to bright light such that the last few seconds of data storage are performed at peak light conditions.

10.

Data storage will be complete when the displayed

“W’ turns off.

12 To disable data recall, press SHIET and then MENU.

For this example, you would expect the current to increase as the source of light increases. In general, the test data should support this. However, because this test was not conducted under ideal conditions, electric fields due to a lack of shielding and induced currents due to cable flexing when moving the LED most likely caused some

“undesirable” readings.

3-28

SECTION 3

Front Panel Operation

Fipre 3-E.

Setup

for

Measure LED Current

3.14.2 Resistivity Tests (Model 487)

Resistivity of insulators can be determined by applying high voltage to the material under test and measuring the subsequent current.

The following operating example will determine the volume or surface resistivity of paper using the V/I ohms function of the Model 487 and the Model 6105 Resistivity Adapter. Be sure to read the instruction manual for the Model 6105 before performing this test.

Equipment Needed: Model 6105 Resistivity Adapter

Model 6147 2-Slot Triax to BNC Adapter (supplied with

Model 6105)

Model 4801 BNC to BNC Input Cable (supplied with

Model 6105)

Model 6171 3-Slot Triax to 2-Lug Triax Adapter Model 237.TRX-T Triax Tee Adapter Model 237.ALG-2 Triax/ Alligator Clip Cable

Procedure:

NOTE Step 1 will return the instrument to factory default conditions. In that state, filter will be enabled (DIG+AN), zero check will be enabled, and autorange will be enabled.

1. Perform the following steps to perform factory initialization:

A. Press and release MENU until the following

message is displayed:

DEFAULTS OK

B. Use the rotary knob to display the following

IlleSSage:

DEFAULTS

C. Press MENU to perform factory initialization.

2. Connect the Model 487 to the Model 6105 as shown in Figure 3-16.

CAUTION Insulate the unused red clip lead of the Model 237- ALG cable to avoid contact.

3. Perform one of the following steps (A or B) to configure the Model 6105 for the desired test:

A. To test surface resistivity, configure the Model

6105 as shown in Figure 3-17. The banana plug cable from the electrode is connected to the

banana jack labeled “SURFACE.” The shorting

plug is installed in the other two banana jacks.

B. To test volume resistivity, configure the Model

6105 as shown in Figure 3-18. The banana plug cable from the electrode is connected to the

banana jack labeled “VOLUME.” The shorting

plug is installed in the other two banana jacks.

FACTORY

3-29

SECTlON 3 Front Panel Operation

L For shipping and during storage, two screw fasten-

ers are used to secure the electrodes. Remove these

,. .,.1

two rasreners If tney are currently mstmea

As shown in Figure 3-17 and Figure 3-18, position

. . . .

the paper sample between the electrodes. Make sure there are no conductive paths between the electrodes other than through the sample. The electrodes must not touch anything except the sample.

6. Close the Model 6105 cover and secure the latch. An interlock switch disconnects power from the sample if the cover is not completely closed.

WARNING The following steps will apply hazardous voltage, that could cause severe injury or

death. Exercise extreme caution when the

V-Source of the Model 487 is in

operate.

7. With the V-source of the Model 487 in standby (OPERATE indicator off), use the 4 and . keys,

and the rotary knob to set the V-source to 500.0OV.

8. Select the V/I ohms function by pressing SHIFT

and then OHMS. The ZERO CHECK indicator will start flashing.

9. Place the V-source of the Model 487 in operate by

pressing OPERATE. 500V will be applied to the paper sample.

6105 ReSiStiVily Adapter

1 Figure 3-17.

Confgurationfor Surface Resistivity

10. On the Model 487, press ZERO CHECK to disable zero check and allow one minute to electrify the

sample.

11. After one minute electrification time, record the resistance measurement (R,) from the display of

the Model 487.

12. On the Model 487, enable zero check and place the V-Source in standby.

3-30

SECTION 3

Front Panel Omzration

where; p is the volume resistivity of the

sample;

3.53 is a constant based on the physical dimensions (in inches) of the elec-

trodes

of the Model 6105;

22.9 is a constant based on the physical dimensions (in centimeters) of the electrodes of the Model 6105;

R, is the V/I ohms reading from the Model 487;

ti is the thickness of the sample in inches;

t, is the thickness of the sample in centimeters.

For example, if the reading on the Model 487

(R,) is 90GQ and the thickness of the paper sample is 5 mils, the volume resistivity is calculated as follows:

13. Calculate the resistivity of the paper sample as follows:

A. If the Model 6105 is configured for surface

resistivity, perform the following calculation:

o = 53.4 R, ohms

where; B is the surface resistivity of the

sample;

53.4 is a constant based on the physical dimensions of the electrodes of the Model 6105;

R, is the V/I ohms reading from the Model 487.

For example, if the reading on the Model 487 (R,) is 90GQ (typical for plain paper), the surface resistivity of the paper sample is calculated as follows:

o = 53.4 x 90GQ = 4.8 x 10%

B. If the Model 6105 is configured for volume

resistivity, perform one of the following calculations:

3.53

p = T RMohm-inches

p = F R, ohm-centimeter

3.53

_ 90GR = 6.35 x 10’30hm-inches

p = 0.005

3.15 SOURCE VOLTAGE/MEASURE CURRENT (Model 487)

For V/I ohms measurements (see paragraph 3.7), the Model 487 is configured to source voltage and measure current. The following paragraphs will summarize how to use the Model 487 in other test systems that require the instrument to source voltage and measure current (Source V/Measure I).

NOTE An operating example to perform resistivity tests is contained in paragraph 3.142.

3.15.1 Basic Source V/Measure I Configuration

The most common configuration to source V and

measure I, as used for V/I ohms measurements, is shown in Figure 3-10. In this configuration the V-source and picoammeter are separately connected to the test fixture.

NOTE Do not connect signal low to ANALOG OUTPUT LO. Always use INPUT LO for input signals.

3-31

SECTlON 3 Front Panel Operation

3.15.2 Testing 2-Terminal Devices

The Model 487 is ideal for sourcing voltage and measuring current to test voltage coefficients of resistors, leakage current of capacitors, and reverse current of diodes. Generally, these tests are performed on high impedance devices allowing either source V measure I configuration to be used. (Figure 3-10).

NOTE For the following test examples, use Figure3-10 as the circuit configuration. The device under test (DUT) is shown installed in the Keithley Model 8002A test fixture.

Voltage Coefficient Tests of Resistors High megohm resistors often exhibit a change in resis-

tance with applied voltage. This resistance change is characterized as the voltage coefficient.

To determine voltage coefficient of a resistor, two V/I ohms measurements at two different voltage values will be required. The voltage coefficient in s/V can then be calculated as follows:

lOO(R, - R1)

Voltage Coefficient (s/V) =

R v

Capacitor Leakage Tests

An important parameter associated with capacitors is leakage current. The amount of leakage current in a

capacitor depends both on the type of dielectric as well as the applied voltage. With a test voltage of lOOV, for

example, ceramic dielectric capacitors have typical leak-

age currents in the n4 to pA range. By using the V/I ohms function, the leakage current measurement can be automatically converted into the insulation resistance ValUe.

When measuring leakage currents on capacitors, stability and noise performance can be maintained by adding a resistor in series with the capacitor under test. The value of this resistor should be around 1MQ. For larger capacitor values (>lpF), the value of the series limiting resistor can be made lower in order to improve settling times; however, values below 1OkQ are not generally recommended.

After the voltage is applied to the capacitor, the device must be allowed to charge fully before the measurement can be made. Otherwise, an erroneous current, with a much higher value will be measured. The time period

during which the capacitor charges is often termed the

“soak” time. A typical soak time is 7 time constants, or 7RC, which would allow settling to less than 0.1% of final value.

where; R, is the measured resistance with the first

applied voltage. R, is the measured resistance with the second

applied voltage. V is the difference between the two applied

voltages.

Example: Assume that the following values are

obtained. R, = 1.01 x 10%

R2 = 1 x 10% v=5v

The resulting voltage coefficient is:

Voltage coefficient (s/V) = loo(* x IO’)

1 x 10’“(5)

Note that the voltage coefficient of a particular device may apply only across the selected voltage range and may vary with different voltage increments in the same

approximate range.

= 0.2%/V

WARNING Hazardous voltage may be present on the capacitor leads after performing this test. Discharge the capacitor before removing it from the test fixture.

Diode Reverse Current Test

The reverse current of a diode can be checked using the

Model 487 to source voltage and measure current. To perform this test, the diode must be reverse-biased

by programming the V-Source to apply a positive (+)

voltage to the cathode of the diode (anode to V-Source common). Forward biasing the diode will, in most cases, cause the Model 487 to go into I-limit.

To check the reverse current of a lN3952 germanium diode, set the V-source of the Model 487 to apply +4.5V to the cathode of the diode. The measured reverse current displayed on the Model 487 should be approximately 4fiA.

3-32

SECTION 3

Front Panel Operation

3.16 MEASUREMENT CONSIDERATIONS

The Model 4861487 is a highly sensitive instrument that

can measure very low current levels. At these low signal

levels, a number of factors can affect a measurement. Some considerations when making measurements with the Model 486/487 are discussed in the following paragraphs.

3.16.1 Source Resistance

As shown in Table 3-10, a minimum value of source resistance (R,) is recommended for each current range. The reason for this can be understood by examining Figure 3-19. Considering the effects on low frequency noise and drift, C, and C, can momentarily be ignored.

Input amplifier noise and drift appearing at the output can be calculated as follows:

Table 3-10. Minimum Recommended

Resistance (RS)

Equation 1

Output E,,,,, = Input ENOISE x 1 + -

( 3

Thus, it is clear that as long as R, >> R, Output ENolsE = Input E,,,,,. When R, = R, Output ENOISt = 2 x Input

hXX. The same applies for E,,. The Model 486/487 will typi-

cally show insignificant degradation in displayed performance with the noise gain of 2 resulting from allowing R, = R, Amplifier E,, can be nulled by using the relative feature. The temperature coefficient of E, is <3O~V/“C. These numbers can be used with Equation (1) to determine expected displayed noise/drift given any source resistance. Note also the values given in Table 3-11 for minimum source resistance also represent the value of R, on that range.

3.16.2 Source Capacitance

Very high input capacitance (CJ may increase noise and

induce instrument instability. The noise gain of the measurement circuit can be found from:

Figure 3-19.

EOS

ENolsE

Simplified Modelfrom Source Resistance and Source Capacitance Effects

Equation 2

Output ENOISE = Input ENOISE

++z,

where: zF = J&

zs=&i&Y

Clearly as f+O, Equation 2 reduces to Equation 1 (see

previous paragraph). The frequency of interest is 0.1 to 300Hz which is the

bandwidth of the A/D converter. The values of C, are

listed in Table 3-11

Table 3-11. Feedback Capacitor (CF) Values

mcitor CC,)

Analog Filter

Enabled

25.3pF

13.3pF

47.3pF

125.3pF

355.3pF

3655.3pF

10355.3pF

Range

2nA

20nA

2oonA

2~4

20~A

ZOOpA

2mA

Feedback C

Analog Filter

Disabled

4pF

13.3pF

25.3pF

103.3pF

333.3pF

3633.3pF

10333.3uF

3-33

SECTION 3 Front Panel Oaeration

In general, as C, becomes larger, the noise gain becomes larger. An application of where C, is very high is leakage measurements of capacitors. In this case, Input ENols, must include the effects of the voltage source (Es) used to bias the capacitor (any noise in the source voltage will increase the input noise).

When measuring leakage currents on capacitors larger than lO,OOOpF, stability and noise performance can be maintained by adding a resistor in series with the capacitor under test. The value of this resistor should be around 1MR. For large capacitor values (>lpF), the value of the series limiting resistor can be made lower in order to improve settling times; however, values below 1OkQ are not generally recommended.

The resistor is not critical in terms of tolerance or stability Any carbon composition resistor will prove adequate.

3.16.3 Triboelectric and Piezoelectric Effects

Unwanted currents may be generated due to triboelectric and piezoelectric effects, and will subsequently be measured by the Model 486/487.

cylinder to equalize charges and minimize charge generated by frictional effects of cable movement. However, even low-noise cable creates some noise when subjected to vibration and expansion or contraction, so all connections should be kept short, away from temperature changes (which would create thermal expansion forces), and preferably supported by taping the cable to a non-vibrating surface such as a wall, bench, or rigid pole.

Other solutions to movement and vibration problems include:

Removal or mechanical decoupling of the source of vibration. Motors, pumps and other electromechanical devices are the usual sources.

Stabilization of the test hookup. Securely mount or tie down electronic components, wires and cables. Shielding should be sturdy.

Triboelectric effects can also occur in other insulators and conductors which touch each other. Therefore, it is important to minimize contact between insulators as well as conductors in constructing test fixtures and connections for low current and high impedance.

Triboelectric Effects Triboelectric currents are generated by charges created

between a conductor and an insulator due to friction. Here, electrons rub off the conductor and create a charge imbalance that causes the current flow. A typical example would be electrical currents generated by insulators and conductors rubbing together in a coaxial cable (see Figure 3-20).

Figure 3-20. Triboelechic Effect

Piezoelectric Effects Piezoelectric currents are generated when mechanical

stress is applied to certain insulating materials. The effect occurs in ceramics and other crystalline materials,

as well as some plastics used for insulated terminals

and interconnecting hardware. An example of a terminal with a piezoelectric insulator is shown in Figure 3-21.

1 Figure 3-21.

Piezoelectric Effect

“Low-noise” cable greatly reduces this effect. It typically uses an inner insulator of polyethylene coated with graphite underneath the outer shield. The graphite provides lubrication and a conducting equipotential

3-34

To minimize the current due to this effect, it is important

to remove mechanical stresses from the insulator and

use insulating materials which have minimal piezoelec-

tric effects, such as sapphire, Teflon@, or PVC.

SECTION 3

Front Panel Operation

3.16.4 Electrostatic interference

Electrostatic interference occurs when an electrically charged object is brought near an uncharged object, thus inducing a charge on the previously uncharged object. Usually, the effects of such electrostatic action are not

noticeable because low impedance levels allow the

induced charge to dissipate quickly. However, high impedance levels of many measurements do not allow these charges to decay rapidly, and erroneous or unsta-

ble readings may be caused in the following ways:

1. DC electrostatic elds can cause undetected errors or noise in the reading.

2. AC electrostatic elds can cause errors by driving

the ampli er into saturation, or through recti cation that produces dc errors.

Electrostatic interference is rst recognizable when hand or body movements near the experiment cause

uctoations in the reading. Pick up from ac elds can also be detected by observing the output on an oscilloscope. Line frequency signals on the output are an indication that electrostatic interference is present.

Means of minimizing electrostatic interference include:

1. Shielding. Possibilities include; a shielded room, a shielded booth, shielding the sensitive circuit (test

xture), and using shielded cable. The shield should always be connected to a solid connector that is connected to signal low. Note, however, that shielding can increase capacitance, possibly slowing down response time.

2. Reduction of electrostatic elds. Moving power lines or other sources away from the experiment reduces the amount of electrostatic interference seen.

3.16.5 Thermal EMFs

Thermal EMFs are small electric potentials generated by differences in temperature at the junction of two dissimilar metals. Low thermal connections should be used whenever thermal EMFs are known to be a problem. Crimped copper to copper connections can be used to minimize these effects.

Sources of EM1 include:

Radio and TV broadcast transmitters.

Communications transmitters, including cellular

phones and handheld radios.

Devices incorporating microprocessors and highspeed digital circuits.

Impulse sources as in the case of arcing in highvoltage environments.

The instrument, measurement leads, and other cables

should be kept as far away as possible from any EMI sources. Additional shielding of the test xture, signal leads, sources, and measuring instruments will often reduce EMI to an acceptable level. In extreme cases, a specially constructed screen room may be required to suf ciently attenuate the troublesome signal.

Many instruments, including the Models 486/487, incorporate internal ltering that may help reduce EM1 effects in some situations. Increasing the programmed

lter rise time will often help to reduce EMI. In some cases, additional external ltering may be required. Keep in mind, however, that ltering or increased rise time may have detrimental effects on the desired signal.

3.16.7 Ground Loops

Ground loops that occur in multiple-instrument test setups can create error signals that cause erratic or erroneous measurements. The con goration shown in Figure 3-22 introduces errors in two ways. Large ground currents owing in one of the wires will encounter small resistances, either in the wires, or at the connecting points. This small resistance results in voltage drops that can affect the measurement. Even if the ground loop current is small, magnetic ux cutting across a large loop formed by the ground leads can induce suf cient voltages to disturb sensitive measurements.

3.16.6 Electromagnetic Interference (EMI)

The electromagnetic interference characteristics of the Model 486 Picoammeter and Model 487 I’icoammeter/ Voltage Source comply with the electromagnetic compatibility (EMC) requirements of the European Union (EU) directives as denoted by the CE mark. However, it is still possible for sensitive measurements to be affected by external sources. In these instances, special precau-

tions may be required in the test setup.

SECTION 3 Front Panel Operation

To prevent ground loops, test system co-on should be connected to earth ground at only a single point, as shown in Figure 3-23. Note that circuit common is connected to earth ground only at Instrument B (via the ground link). The ground link for Instrument A has been removed. Experimentation is the best way to determine an acceptable arrangement. For this purpose, measuring instruments should be placed on their lowest ranges. The con guration that results in the lowest noise signal is the one that should be used.

3.16.8 Floating Measurements

CAUTION To prevent damage to the instrument, adhere to the following precautions when eating the input above chassis ground:

1. Do not connect ANALOG OUTPUT LO

to CHASSIS. If there is a ground link installed at the rear panel binding posts, remove it.

2. Make sure that any monitoring instm-

ment connected to the analog output is

eating.

The circuit connected to the input of the Model 4&36/487 in Figure 3-24 shows a typical con guration to make

eating measurements. A problem occurs when ANALOG OUTPUT LO is connected to chassis ground. As shown in the illustration, connecting ANALOG OUTPUT LO to chassis ground will provide a current

path for the voltage source through the internal fusible

resistor R203. In this con guration, a voltage source with high current capabilities could damage the resistor. For example, if voltage source (E) is set to 1OOV and has a lOOmA limit, current through R203 could be lOOmA (lOOV/lkn=lOOmA) damaging the l/ZW fusible resistor.

If the V-Source of the Model 487 is used to make eating measurements, damage to R2.03 cannot occur because of the 2.5mA limit. However, the measurement could be compromised if the V-Source is forced into current limit.

Figure 3-24. Improper Method to make Floating Measurements

3-36

SECTION 4

IEEE-488 Reference

4.1 INTRODUCTION

The IEEE&?8 bus Is an instrumentation data bus with hardware and programming standards originally

adopted by the IEEE (Institute of Electrical and Electronic Engineers) in 1975 and given the IEEE-488 designation. In 1978, standards were upgraded Into the IEEE-488-1978

standards. The Models 486 and 487 conform to these

standards.

This section contab reference Information on programming the Model 486/487 over the IEEE-488 bus. Detailed instructions for all programmable functions are included, however, information concerning operating modes presented elsewhere is not repeated. Refer to Sections 2 and 3 for information not found in this section.

Additional information on the IEEE-488 bus is located in the appendices.

NOTE

The programmed examples used in this sec-

tion are written Hewlett Packard BASIC version 4.0. This language was chosen because of its versatility in con!ndling the IEEE-488 bus.

Command Syntax-Each command is made up of a single ASCII capital letter followed by one or more numbers orlettersrepresentinganoption ornumericparameter of that command. For example, the integration time can be set over the bus by sending the letter “S” foIlowed by a number representing the integration time option. SOX

would be sent to program a 1.6msec integration time.

Sending a command without an option (such as RX) is the same as not sending a command. However, it wiU take time to process the command.

Ifacommandappears more thanonceinanX-terminated s&g, only the last occurrence of the command is executed -the others are ignored.

Multiple Options options that must be separated by commas. For example, a V5,OJX command programs the voltage source of the Model 487. In this case, the 5 is the value of the voltage source (+5v), 0 is the voltage source range (SOW, and the

1 is the current limit option (2mA).

Options of a multiple option command may be defaulted as demonstrated in the following examples:

VlOX Set V-source to 1OV. Range and l-limit will de-

fault to currently programmed parameters.

Some

commands have two or more

4.2 DEVICE-DEPENDENT COMMAND

PROGRAMMING

IEEE-488 device-dependent commands are the most important co mmands associated with instrument programming because they control most instrument operating modes. The IEEE-488 bus actually treats these commands as data, in that they are sent with ‘dw ATN line false.

Most Model 486/487 front panel operations (such as range selection) as well as some operations not available from the front panel (like SRQ and terminator) can be program&d with these commands.

V60,lX Set V-source to 60V on the 5DDV range, and de-

fault l-limit.

v,ox Default V-source, select5OVrange, and default

l-limit.

v,,ox

Multiple Commands -A number of commands can be grouped together in one command string, which is generally terminated by the “X” character. This character tells the inskument to execute the command or com-

mand string, as desaibed in paragraph 4.2.22. Com-

mands sent without the execute character will not be executed at that particular time, but they will be stored

Default V-source, default range, and set I-limit to 25H.

4-1

SECTION 4 IEEE-488 Reference

within an internal command buffer for later execution when the execute character is tially received.

v4,o,ox

Multiple-option co

mmand string (options

separated by commas).

Invalid Commands - If an invalid command is sent as part of the command string, no co

mmands in the string will be executed. Under these conditions, the instrument will display a front panel error message (IDDC or IDDCO) and it can be programmed to generate an SRQ (ServiceRequest),asdiscussedinparagraph4.2.11.Commands are checked es they are received. When an illegal command is received, all other commands since the previous X and until the next X are ignored.

Some typical examples of valid co

nunand strings in-

clude:

ROX

Single command followed by execute commend.

Y4SOPOX Multiple command string. 21X

Space is ignored

Table 4-l. Device-dependent Command Summary

Mode Display Intensity

Command Description

Normal display Dim display

Turn display off

Typical invalid command strings include: ElX

Invalid command, as E is not one of the instrument’s valid commands.

K6X

Invalid command option because 6 is not an option of the K commend.

N600X

Invalid parameter (buffer size cannot exceed

512).

22.001X Multiple-option command

without the nec-

essary separating commas.

Device-dependent Command Summary - All Model 486/487 device-dependent commands are summarized inTable4-1,whichalsolistsrespectiveparagraphswhere

more detailed information on each command may be found.

PU&

4.2.1

Reading Source

Zero Check and Correct

Display

V/I ohms

Data Format

BO Bl B2 83

B4 co :: Da

FO Fl

Readings from A/D single reading from data store All readings from data store Mexirnum reading from data store Minimum reading from data store

Disable zero check Enable zero check Enable zero check and perform zero correction

Display up to 18 character (a) message Cancel display mode

Disable V/I ohms Enable V/I ohms

ASClIrdgstithprefiv

ASCII rdgs without prefix ASCII rdgs and buffer locations with prefix ASCII rdgs and buffer locations without prefix Binary rdgs: IEEE Std 754 single-precision, bytes reversed for Intel CPUS

Binary rdgs: IEEE Std 754 single-precision, bytes in normal order for Motorola CMJs

4.2.2

4.2.3

4.2.4

4.2.5

4.2.6

SECTION 4

IEEE-488 Reference

Mode kita Format

Cant).

lit Control

ielf-Test

Command Description

G6 Binary rdgs: counts and exponent, bytes reversed for Intel CPUs G7 Binary rdgs: counts and exponent, bytes in normal order for

Motorola CPUs

Hl Ii2 H3 H4

E zi

H10

H11 HI2 H13 H14 H15 HI6 H17

Hit DISPLAY INTENSlTY key Hit LOCAL key Hit SHET key Hit MENU key Hit ZERO CHECK key Hit FILTER key Hit RANGE V key Hit REL key Hit RANGE A key Hit SETUP key Hit TRIGGER key Hit OPERATE key (487) Hit PRESET key (487) Hit4 Hit,

Hit Rotary Knob counterclockwise

Hit Rotary Knob clockwise Perform ROM/RAM self-test

Perform display and ROM/RAM self-test

Paa.

4.2.7

4.2.8

iO1 and lus Hold-off

default Conditions )r Calibration

iRQ

Ma Store

werate

KO Kl Disable EOI, enable bus hold-off on X K2 K3

LO E

Lx”

IA w L6

g M2 Data store full M4

MM M32 ElT0r

Ml28

NO Arm data store; wrap around operation

Nil

00 Place voltage source in standby 01

Enable EOI and bus hold-off on X Enable EOI, disable bus hold-off on X

Disable both EOI and bus hold-off on X

Return to factory default conditions and save (Ll)

Save present states as default conditions Return to saved default conditions Calibrate present measurement range using “v”; v = -2E-3 to +2E-3

“Ps Calibrate zero on present voltage source range (Model 487 only)

Calibrate full scale on present voltage source range Model 487 only) Prepare to calibrate present voltage source range (Model 487 only)

Disable SRQ Reading overflow

Data store half full Reading done Ready

Voltage Source Error (Model 487 only)

Arm data store; set buffer size “n” where n = 1 to 512

Place voltage source in operate

4.2.9

4.2.10

4.2.1

4.2.12

4.2.13

SECTION4

IEEE-488 Reference

&de 1 Command 1 Descriution uters

nterval

Lange

ntegration

. .

.ngger

Pl n

Eif

2 z

z R-7

Fta R9

RIO Disable autorange

Tl One-shot on Talk T2 T3 T4 Multiple on X

Disable digital and analog filters Enable digital filter; disable analog filter Disable digital filter; enable analog filter Enable digital and analog filters

175msec (factory default) Set to “n” seconds. n = O.OlOsec to 999.999sec

Enable autorange Select 2nA range Select 2OnA range sekct 2mnA range Select &A range Select 2op.A range Select 200@ range Select 2mA range No range No range

Fast integration; 1.6msec at 4-l /2 digit resolution Line cycle integration; 16.67msec @4Wz) or 20msec (5OI-W at 5-l/2 digit resolution

Multiple on Talk Multiple on GET

One-shot

I Para.

4.2.15

4.2.16

4.2.17

4.2.18

GET

Multiple on Operate (48$-

One-shot on

uo 2

u3 u4 u5 U6

u7 US u9

Joltage Source ‘487) n: -505 to +505

Vn,r,l

Send machine status word Send error status word Send model number and firmware revision

Send calibration value Send interval Send delay Send relative value for current Send relative value for V/I ohms Send voltage source value (487) Send voltage source error status word (487)

Specify voltage source level “n” in volts, range “I-” and limit “3”

r 0 = 5ov range; 1 = 5oov range ko=2opAlimit;l=2mAlimit

Operate (487)

4.2.19

4.2.20

Device-dependent Command Summary (Cont.)

SECTION 4

IEEE-488 Reference

Mode Delay Execute Terminator

Relative

Command

YO Yl Y2 Y3 Y4

20 Zl

Z&V

z.3

Description Delay trigger “n” seconds; n = 0 to 999.999sec Execute other device-dependent commands CR LF

LF CR CR LF None

Disable relative Enable relative using present reading as baseline Enable relative using ‘Y as baseline; v = -ZE-3 to +ZE-3 amps for current, v = 00 to 50.5E16Q for V/I ohms Enable relative using the baseline previously defined

PiUa.

4.2.21

4.2.22

4.2.23

4.2.24

SECTIOh’4 IEEE-488 Reference

4.2.1

A - Display Intensity

Purpose

Format An

Parameters

Default

Description

To control the brightness of the display and front panel indicator lights.

A0 Select normal display Al Select dim display A2 Turn display off

Upon power-up, or after receiving a DCL or SIX command, the instrument returns to the display intensity that was saved as the default condition.

Control of display intensity isusefulin applications wherethelight from the display and indi-

cators could be detrimental to an experiment or test.

The Al command dims the display and indicators. In low ambient light conditions, the display

and indicators are still easily read. The A2 co mmand turns the display and indicators (except POWER)completelyoff.Thepowerswitchindicatorremains dimlylittodenotethattheinstrument is on.

Programming

Examples

OUTPUT 722; “AIX”

OUTPUT 722; “Aze

OUTPUT 722; “AOX”

! Dim the display. ! Turn the display off.

! Return display to normal.

SECTION 4

IEEE-488 Reference

4.2.2

Purpose

Format

Parameters

- Reading Source

To select the source of data (A/D converter or data store) that is transmitted over the bus.

BO Select A/D converter readings for output to bus Bl Select single data store reading for output to bus

82 Select all data store readings for output to bus 83 Select miudmum value reading in data store for output to bus. B4 Select minimum value reading in data store for output to bus.

Upon power-up or after receiving a DCL or SDC command, the instrument returns to the option of the B comman d that was saved as the default condition.

With this command, the user has a choice of data from the A/D converter or the buffer (data store). When in BO, A/D readings will be sent. In a continuous trigger mode, readings will be updated at the conversion rate. The Bl buffer. When the Bl co buffer locations beginning with the first memory location @Ol). Once all readings have been taken, the instrument will not send any more readings until another B command is received or another data store operation is started.

co mmand is used to access single readings from the

mmand is sent, subsequent readings will be taken from consecutive

Programming

Notes

Programming

Examples

The B2 command allows you to dump the entire data store contents to the computer in one op

eration. Individual ASCII readings will be separated by commas.

The 83 command allows you to send the madmum reading from the data store buffer to the computer, while the B4 command is used to obtain the minimum reading.

The programmed terminator and EOI will be asserted at the end of the complete dumpnot after each reading as is the case with Bl.

In Bl or BZ, nothing will be transmitted over the bus until data is stored in the data store.

The selected data format (see G command) will apply to each reading sent over the bus to the controller.

REMOTE 722

OuTPLrl- 722; “Box”

20 30

E!NTER722;A$

FRINTAS l7.m

50 OlYY

! Select A/D reading mode. ! Acquire reading from 4&36/487. ! Display reading on CRT.

SECTION 4

IEEE-488 Reference

4.2.3

Parameters

Description

C - Zero Check and Zero Correct

Purpose

Format

Default

Use to cancel any internal offsets that might affect accuracy.

Upon power-up, or after receiving a DCL or SIX command, the instrument will return to the state (CO or Cl) that was saved as the default condition. The instrument will return to

zero correction parameters that are saved as default conditions.

Normal current measurements are performed when zero check is disabled (CO). When

zero check is enabled (Cl), a large impedance (lOOk& appear at the input and any internai offset is presented at the output of the input amplifier and measured (see paragraph

3.5.3).

Disable zero check Enable zero check Enable zero check and perform zero correction

Programming

Notes

Programming

Example

When c2 is sent over the bus, zero check is enabled and zero correction occurs. For zero correction, the measured of&et is stored and algebraically subtracted from subsequent readings. After correction is performed, zero check returns to its previous state (enabled or disabled). A separate zero correction needs to be performed for each range.

1. Zero correction should be performed whenever the display is not zeroedwhen in zero

check.

2. The specifications at the front of this properly zeroed.

3. When in autorange, zero correction will be performed on the range the instrument is currently in.

OUTPUT 722; ‘XIX”

OUTPUT 722; “c2x”

manual

assume that the instrument has been

! Select 1nA range. ! Zero comect InA range

SECTION 4

IEEE-488 Reference

4.2.4 D

Purpose

Format

Parameters

Description

Programming

Notes

- Display

To display messages on the front panel.

Da Display characters “a”, where “a” represents printable ASCII characters. D Return display to normal operation.

Upon power-up, or after receiving a DCL or SDC command, the display returns to normal op eratim.

TheDco ing blanks, can be sent by simply following the D that can be displayed include; O-9, A-Z (except uppercase X), arithmetic and most punctuation

symbols.

1. Spaces in a message are displayed as blanks.

2. Sending a message that exceeds 18 characters will result with only the first 18 characters

3. For messages that are lees than 18 character in length, the characters are left-hand justified

4. Pressing LOCAL on the front panel will cancel the message and rehrn the instrument to

mmand allows you to display messages on the front panel. Up to 18 characters,includ-

being displayed. The extra characters will be ignored. and the rest of the display is blank. the normal display state.

comman

d with ASCII characters. Characters

Programming

Examples

OuTpuT 722; “D MODEL 486X” OUTPUT 722; ‘JDY

! Display “MODEL 486”. ! Return display to normaL

SECTION 4 IEEE-488

Reference

4.2.5

Purpose

Format

Parameters

Default

Description

F - V/I Ohms

To control the V/I ohms function of the Model 487.

FO Disable V/I ohms Fl Enable V/I ohms

Upon power-up or after receiving a DCL or SDC command, the instrument returns to the op-

tion of the F command that was saved as the default condition.

For V/I ohms, resistance is automatically calculated (and displayed) from the applied voltage and the measured current in accordance with Ohms Law: R = V/I.

For complete

information

on using V/I ohms, refer to paragraph 3-7.

Programming

Examples

OUTPUT 722; “FIX” OUTPUT 722; ‘TOX”

! Enable V/I ohms.

! Disable V/I ohms.

4-10

SECTION 4

IEEE-488 Reference

4.2.6

Purpose

Format

Default

Description

G - Data Format

Control the format of output data that is transmitted over the bus.

GO ASCII readings with prefix Gl ASCII readings without prefix G2 ASCII readings and buffer location with prefix G3 ASCII readings and buffer location without prefix G4 Binary readings - IEEE Std 754 single-precision, bytes reversed for Intel CPLJs.

G5 Binary readings-IEEE Std 734 single-precision, bytes in normal order for Motorola U’Us. G6 Binary readings - counts and exponent, bytes reversed for Intel CPUs. G7 Bixwy readings-counts and exponent, bytes in normal order for Motorola CRJs.

Upon power-up, or after receiving a DCL or SDC command, the instrument will return to the data format that was saved as the default condition.

Whenever the instrument is addressed to talk, it sends data over the IEEE-488 bus to the controller. The format of output data is determined by how it is configured with the G command. Figure 4-1 shows an example of an ASCII output data string that indudes the buffer location and prefix.

Prefix Mantissa Exponent Suffix

r--hA4-l~

NDCl~1.23456Ek.03.000

= Nonal Reading

2 = Rel’ ed Reading

= Overflowed Reading or Underflowed Reading, (V/I Ohms)

Figure 41. ASCIIDatnFonnat (G2;Prefxand Suffix

The Model 486/487 can be programmed to output data in a binary format to CPUs. The binary data formats are shown in Figures 42 and 43. Note that the headers for these

binary formats are shown in Figure 44.

Motorola or Intel

411

SECTION 4

IEEE-488 Reference

G6 Fonat (Reverse order : Intel CPU) :

Header *

6 Bytes 1 LSB 1

ReqdinQ **

) MSB ( LSB 1

MSB * * *

‘igwe 4-2.

d”tS

(16 bit signed)

G7 Format (Normal order : Motorola CPU) :

Header *

Bytes

1 MSB 1

1 LSB 1 MSB 1 1 LSB --*

Reading **

co:nis Expdnent

* Headers for the G6, and 07 formats are shown in Fig. 4-4

**When recalling data from the buffer, one header

is followed by one or more readings, depending on buffer size.

NOTE : True reading = Counts X lOExponent

G6 and G7 Bina y Data Formats (Counts/Exponent)

05 Format (Normal order ; Motorola CPU)

Header *

r--l-

Bytes

lByteljByte2)Byte31Byte4 ---

Reading **

Expdnent

(16 bit signed)

** When recalling data from the buffer, one header

%we 4-3.

Sign Jk$Marltissa

(1 Bit) (8

G4 Format (Reverse order ; Intel CPU) : Reading bytes sent in reverse order ;

‘Headers for the G4 and G5 formats are shown in Fig. 44

is followed by one or more readings, depending

on buffer size.

G4 and G5

Bimrv Data Formats

Bits)

(single precision, IEEE-754)

(23 Sits)

Header*, Byte 4, Byte 3, Byte 2, Byte 1

(IEEE

Std. 754)

and G7 Header (6 bytes) :

SECTION4

IEEE-488 Reference

MSB LSB

Data Forma! : 0000000 = CounisfExponeti OWOOOl = IEEE Bid 754

I-

Byte Order : 0 = Nond (Motomla) 1 = rieversec (Intel)

and G6 Header (6 bytes) :

-Byte Order : 0 = Nom4 (Motorola) 1 = Revemed (Intel)

L7--l -

Function : 000001 = current 000011 = “,I Ohms

Reserved

- 1 = REL enabled

F&on : 000001 = cument 000011 = vi, Ohms

Reserved

-1 = REL enabled

Byte-Count”

(1 &bit unsigned)

The ASCII dataformat is ina directreadable form fortheoperator. Most BASIC languageswill eady convert ASCII mantissa and exponent to other formats. However, some speed is cornpromised to accommodate the conversion.

The Count and Exponent format has some advantages over the ASCII format. It require fewer bytes, transfers to the computer faster, and is compatible with most programming languages. This format is particularly useful when collecting data on a fixed range (autorange disabled).

The IEEE Standard 754 Single Precision format requires few bytes, and is used without conversion in popular personal computer programming languages.

4-13

SECTION 4

IEEE-488 Reference

Programming 1.

Notes

Programming lo

Examples 20

30 ENTER 72.2; A$ 40 50

The B command affects the source of the data. In the BO modes, the bus data will come from the A/D converter. In the Bl and BZ modes, the data will come from the buffer (data store).

Programmed terminator and EOI sequences appear at the end of each reading except in BZ which teminates only at the end of the string. If a buffer location is not available, 000 is sent. For an overflowed reading, k9.87E37 appears in the data field. When in V/I Ohms, Rel status in the data format only applies to V/I Ohms Rel. That is, if a quantity of resistance was established as a baseline Rel level, “Rel enabled” will be indicated in the data format. Current Rel (on or off) has no effect on Rel status for V/I ohms.

For an underflowed reading. 9.87OOe-37 appears in the data field.

REMOTE 722 OUTPUT 722; "BOGOX"

PRINT A$ END

! Program for A/D ASCII reading with prefix. ! Send reading. ! Display reading on CRT.

4-14

SECTION 4

IEEE-488 Refermce

4.2.7

H - Hit

Purpose

Format

Parameters HI

COIltrO~

Emulate front panel control actions.

Hit DISPLAY INTENSlTY key

Hit LOCAL key H3 Hit SHIFT key H4 Hit MENLJ key H5 Hit ZERO CHECK key

H6 Hit FILTER key I-i7 Hit RANGEV key

Hit REL key H9 Hit RANGE A key

H10 Hit SETUP key HI1 Hit TRIGGER key HI2 Hit OPERATE key (Model 487) H13 Hit PR?BW key (Model 487) H14 Hit4 key

Hl5 Hit .key H16 Hit Rotary Knob countercloclwise

H17 Hit Rotary Knob clodcwise

Description

Programming

Note

Programming

Examples

The hit command allows you to emulate vbtually any front panel panel control sequence. The

result of sending HI through H15 is the same as physically pressing the appropriate front panel key. Sending H16 emulates tuning the Rotary Knob one detent position counterclockwise.

H17 is similar, but emulates turning the Rotary Knob one detent position dockwise.

Second functions of front panel keys are selected by first sending H3 (SHIFT). For example, to zero correct the instient, send H3XHSX. This command stig emulates pressing SHIFT and thenzERocHEcK.

Important consideration: To force a command sequence to emulate front panel actions, each H command must be termina onstrates this. H3H5X is executed as H5X.

The H12 and H13 commands are invalid for the Model 486. Sending these commands to the Model 4% will result in an illegal device-dependent command option (IDDCO) error.

OUTPUT 722; “H6X”

OUTPUT 722; ‘,H3xH7x”

ted by an X. The previous example (H3XH5X; zero correction) dem-

! Hit FILTER key. ! Hit SHIFT V (autorange).

4-15

SECITON 4

IEEE-488 Reference

4.2.8

Purpose

Format

Parameters

Description

J - Self-Tests

To perform self-tests on its memory elements and/or display.

JO Perform ROM/RAM self-test Jl Perform display and ROM/RAM self-tests

Both JO and Jl will perform tests on its memory elements (ROM and RAM). In the event of a

failure, one or both of the following messages will be displayed: ROM ERROR

RAM ERROR

The Jl co mmand will also cause the display test to be run. For this test, each segment of all the

LEDs will be sequentially displayed. Then, all segments of each LED will sequentially dis-

played. The display test ties approximately 17 seconds to complete.

Programming

Example

The UO and Ul status words can be examined to check for self-test errors.

OLn-MJT 72.2; ‘71X”

! Perform display and memory tests.

Keithley 487, 486 Service manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Safety Precautions

SPECIFICATIONS

Table of Contents

List of Illustrations

List of Tables

1.1 INTRODUCTION

1.2 FEATURES

1.4 MANUAL ADDENDA

SAFETY SYMBOLS and TERMS

1.6 SPECIFICATIONS

1.3 WARRANTY INFORMATION

1.7 INSPECTION

1.6 OPTIONAL ACCESSORIES

2.1 INTRODUCTION

2.2 FRONT AND REAR PANEL CONFIGURATION

2.3 BASIC FRONT PANEL OPERATION

2.4 BASIC IEEE-488 OPERATION

3.1 INTRODUCTION

3.2 POWER-UP PROCEDURE

3.3 ERROR MESSAGES

DATA ENTRY; BASIC RULES

3.5 CURRENT MEASUREMENTS

3.6 USING THE VOLTAGE SOURCE (Model 487)

3.7 V/I OHMS MEASUREMENTS (Model 487)

3.8 MENU

3.9 FRONT PANEL TRIGGERING

3.10 EXTERNAL TRIGGERING

3.11 DATA STORE

3.12 ANALOG OUTPUT

3.13 TALK-ONLY

3.14 OPERATING EXAMPLES

3.15 SOURCE VOLTAGE/MEASURE CURRENT (Model 487)

3.16 MEASUREMENT CONSIDERATIONS

4.1 INTRODUCTION