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Model 6487 Picoammeter/Voltage Source User's Manual

1. eese eene eene eene nnns B 2 Wii DOGS CWC e etis siriani B 3 Piezoelectric and stored charge effects B 3 Electrochemical eects siriani Hes etd ooa Phal B 4 IY UTI MM T B 4 bru e P sees bece B 4 Electrostatic interference in B 4 Ma brnetic HeldS scuri B 5 Electromagnetic Interference EMI B 5 Example Programs Programming amplesso C 2 1000 readings second into internal buffer C 2 900 readings second to IEEE 488 bus C 3 3000 readings into internal buffer C 4 1 Figure 1 1 Figure 1 2 2 Figure 2 1 Figure 2 2 Figure 2 3 Figure 2 4 Figure 2 5 Figure 2 6 Figure 2 7 Figure 2 8 Figure 2 9 3 Figure 3 1 Figure 3 2 7 Figure 7 1 Figure B 1 Figure B 2 List of Illustrations Getting Started LEOUEDABEL RARE RE RR RE RE ATA 1 7 Rear panel lierna 1 10 Connections Triax input connector pra 2 2 Maximum input levels 2 3 Basic current measurement connections 2 4 Basic ohms connections 2 5 Shielding for measurements unguarded 2 6 General purpose test fixture connections sse 2 7 Typical connections for measurements using the Model 8009 test fixture
2. 1 8 Getting Started Model 6487 User s Manual NOTE To modify a key s properties press the CONFIG LOCAL key see Special keys and power switch and then the key Not all keys have configurable properties 1 Special keys and power switch CONFIG LOCAL MENU POWER When in Local operation use to configure properties of the next button pressed W hen in Remote operation REM annunciator lit cancels GPIB remote mode Provides access to menu Power switch In position turns 6487 on I out position turns it off O 2 Function keys TO MATH FILT ZCHK REL O PER V SOURCE A V SOURCE W Use to toggle between regular current measurements and ohms Turns on the selected M ath function selected using the CONFIG gt gt MATH key sequence Turns on the filtering selected using the CONFIG gt gt FILT key sequence U se to perform a Zero Check function U se to control and configure properties of the rel ative function Toggles the Vsource state the V source state is displayed by an indicator Configured using the CONFIG gt gt OPER key sequence Increments voltage source value Decrements voltage source value 3 Operation keys COMM DISP TRIG LIMIT DIGITS RATE lt andb SAVE SETUP STORE RECALL AZERO DAMP EXIT EN TER Use to control and modify communication properties GPIB or RS 232 Use to turn display on off Trigger measurement s Takes 6487 out of idle state U se also t
3. 3 13 Range U nits Digits Rate and Filters Measurement TANCES cios euren are betstbma su isliy esa enu ub rtu EE qu Ra do MEG ppRS 4 2 SCPI commands range and digits 4 3 SCPI commands filters i 4 6 Relative mX b m X b reciprocal and log SCPI commands relative NUll eens 5 2 SCPI commands mX b m X b and log 5 4 Buffer and Sweeps SCPI commands buffer sss 6 4 SCPI commands SWeeDS eremie is cU apis Cla ds POUR T EUR 6 5 Remote O peration and Commands General bus commandS iii 7 4 Signal oriented commands sse 7 5 IEEE 488 2 common commands and queries 7 5 SCPI command subsystems sss 7 6 Getting Started Introduction Description of the Model 6487 Picoammeter Overview of this manual Provides content of this manual General information Covers general information that includes warranty infor mation contact information safety symbols and terms inspection and available options and accessories Features Summarizes the features of Model 6487 Front and rear panel familiarization Summarizes the controls and connectors of the instrument as well as providing information on the front panel display Power up Covers line power connection line
4. Manual ranging To select a range press the manual RANGE key The instrument changes one range per key press If the instrument displays the OVRFLOW message on a particular range select a higher range until an on range reading is displayed Use the lowest range possible with out causing an overflow to ensure best accuracy and resolution Autoranging When using autorange the instrument automatically goes to the most sensitive available range to measure the applied signal Up ranging occurs at 105 of range while down ranging occurs at the range value The AUTO key toggles the instrument between manual ranging and autoranging The AUTO annunciator turns on when autoranging is selected To disable autoranging press AUTO or a manual RANGE key Pressing AUTO to disable autoranging leaves the instrument on the present range Every time an autorange occurs a search for every available range of the selected function is performed The time it takes to perform the search could slow down range change speed significantly Setting upper and or lower autorange limits can reduce search time Autorange limits Search time for finding the correct amps range can be reduced by setting upper and or lower autorange limits To set upper and or lower autorange limits press CONFIG then either manual RANGE key for UPPER or LOWER then scroll through the available range limits using the RANGE keys Press ENTER when the desired range is flashing M odel
5. 2 7 Interlock connections siriani 2 9 Typical analog output connections sessssss 2 10 Measurements and Sourcing Voltage Connections for current measurements iii 3 6 Connections for ohms measurements ii 3 10 Remote O peration and Commands IEEE 488 and RS 232 connector locations 7 3 General Measurement Considerations Power line ground loops eeeeeeeeeeeeene B 2 Eliminating ground loops B 3 List of Tables 1 Table 1 1 Table 1 2 2 Table 2 1 3 Table 3 1 Table 3 2 Table 3 3 Table 3 4 Table 3 5 Table 3 6 Table 3 7 4 Table 4 1 Table 4 2 Table 4 3 5 Table 5 1 Table 5 2 6 Table 6 1 Table 6 2 7 Table 7 1 Table 7 2 Table 7 3 Table 7 4 Getting Started DAD 1 16 MENU Stetit iaia ri ia 1 18 Connections Summary of measurement considerations 2 11 Measurements and Sourcing Voltage Basic current measurement capabilities 3 2 Basic voltage source output capabilities 3 2 SCPI commands zero check and zero correct 3 4 SCPI commands basic current measurements 3 7 SCPI commands basic ohms measurements 3 10 Voltage source current limits 3 12 SCPI commands voltage source
6. oet buffer size to 2000 Clear buffer Set storage control to start on next reading Enable buffer full measurement event Enable SRO on buffer full measurement event Operation complete query synchronize completion of commands Start taking and storing readings Wait for GPIB SRQ line to go true Turn display back on Request data from buffer Model 6487 User s Manual Example Programs C 3 900 readings second to IEEE 488 bus This program uses multiple reading queries to get high speed measurements over the bus in real time To improve continuity of readings reduce the trigger count To improve throughput increase the trigger count NOTE This program configures the Model 6487 to 0 01 PLC digital filters off front panel off auto zero off binary transfer and IEEE 488 1 language Model 6487 must be set to IEEE 488 1 operation from the front panel Press CONFIG then COMM select LANG 488 1 then press ENTER See reference manual for details SRO FORM ELEM READ FORM BORD SWAP FORM DATA SRE DEL 0 COUN 8 TRIG TRIG 01 002 NPLC RANG So ACH ORF SYST AZER STAT IOP DISP ENAB OFF ZOPE read back result of opc 1 to 1000 the Model 6487 for i talk read back the binary data next i DISP ENAB ON Return 6487 to RST defaults Return readings only Set for swapped byte order Return single precision floating point Dinary Set trigger delay to zero seconds Set
7. relative This program fragment establishes a 1uA baseline for measurements CALC2 NULL OFFS le 6 Set Rel value of IMA CALCZSNULLTSIAT ON Enable Rel Sole cH ORE Turn off zero check INIT Trigger reading CALC2 DATA Request Rel ed reading mX b m X b reciprocal and Logarithmic mX b and m X b The following math operations manipulate normal display readings X mathematically according to the following calculations Y mX b Y m X b where X is the normal display reading m and b are user entered constants for scale factor and offset Y is the displayed result NOTE Changing the m or b for mX b also changes it for m X b Logarithmic This calculation converts input readings to logarithm base 10 values The calculation is performed as follows log 10 where X is the input reading y is the logarithmic result For example Assume that exactly ImA is being measured by the Model 6487 log 91 000000mA 3 NOTE This calculation uses the absolute value of the normal input reading as the log of a negative number cannot be computed 5 4 Relative mX b m X b reciprocal and log M ode 6487 User s Manual Configuring math functions To select and configure math functions from the front panel press CONFIG then MATH Select the math function to configure then enter the required parameters for mX b and m X b m b and units Once a math function is selected simply press the MATH key to toggl
8. KEI I HLEY M ode 6487 Picoammeter Voltage Source U ser s M anual A GREATER MEASURE OF CONFIDENCE 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 proves to be defective To exercise this warranty 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 or 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 or problems arising from normal wear or failure to follow instructions THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES EXPRESSED OR IMPLIED INCLUD ING ANY IMPLIED WARRANTY OF
9. quency The factory default setting is auto detect enabled If the power line is noisy auto detect may not be able to lock in on a frequency If this Occurs set the frequency manually This may be accomplished using the front panel or over the bus From the front panel use the MENU LFREQ selection to change the fre quency Via remote send the SYST LFR freq command 1 14 Getting Started Model 6487 User s Manual Power up sequence The following power up sequence occurs when the Model 6487 is turned on l The Model 6487 performs self tests on its EPROM and RAM with all digits and annunciators turned on At power up the VOLTAGE SOURCE OPERATE LED will come on for 0 7 seconds to indicate that it is functional If a failure is detected the instrument momentarily displays an error message and the ERR annunciator turns on Error messages are listed in Appendix B of the Model 6487 Reference Manual NOTE Ifa problem develops while the instrument is under warranty return it to Keithley Instruments Inc for repair If the instrument passes the self tests the firmware revision levels are displayed For example 6487 A01 After the firmware revision levels are displayed the detected line frequency is displayed For example FREQ 60HZ After the detected line frequency is displayed information on the selected remote interface is displayed a GPIB If the GPIB is the selected interface the instrument will display the
10. 505 VDC ANALOG OUTPUT Scaled voltage output inverting 2V full scale on all ranges 2 5 2mV ANALOG OUTPUT IMPEDANCE 1000 DC 2kHz VOLTAGE SOURCE Range Step Size Accuracy Noise p p Temperature Typical Rise Typical Fall Max typical 396 PROG OFFSET 0 1 10Hz Coefficient Time 68 Time 78 18 C 28 C 0 70 R H 10 90 9096 1090 310 100 200uV 0 1 1mV ouv 0 005 20uV C 250 us 150 us 250 500 ImV 0 1 4mV lt 150uV 0 005 200uV C 250 us 300 us 505 00 10mV 0 15 40mV L5mV 0 008 2mvV C 4 5ms lms SELECTABLE CURRENT LIMIT 2 5mA 250uA 25uA for 50V and 500V ranges 25mA additional limit for 10V range All current limits are 20 35 of nominal WIDEBAND NOISE lt 30mVp p 0 1Hz 20M Hz TYPICAL TIME STABILITY 0 003 1mV over 24 hours at constant temperature within 1 C between 18 C 28 C after 5 minute settling OUTPUT RESISTANCE 22 50 VOLTAGE SWEEPS Supports linear voltage sweeps on fixed source range one current or resist ance measurement per step Maximum sweep rate 200 steps per second Maximum step count 3000 Optional delay between step and measure RESISTANCE MEASUREMENT V I Used with voltage source resistance calculated from voltage setting and measured current Accuracy is based on voltage source accuracy plus ammeter accuracy Typical accuracy better than 0 6 for readings between 1kQ and ITO ALTERNATING VOLTAGE RESISTANCE MEASUREMENT
11. Ground loops B 2 Handle 1 9 Handling precautions 1 3 Humidity B 4 IEEE 7 3 IEEE 488 1 11 IEEE 488 2 common commands and queries 7 5 Input 1 10 cables connectors and adapters 1 4 connector 2 2 Inspection for damage 1 3 Instruction Manual 1 6 Interface available 7 2 INTERLOCK 1 11 Interlock 2 8 2 9 Light B 4 LIMIT 1 8 Line frequency 1 13 Line power connection 1 13 Logarithmic 5 3 Low noise input cables 2 3 LSTN 1 9 Magnetic fields B 5 Manualranging 4 2 MATH 1 9 Maximum 2 3 Maximum input levels 2 2 measurement 2 11 Measurement considerations 2 9 B 2 Measurement overview 2 2 3 2 Measurement ranges 4 2 Measurements 3 1 MED 1 9 Median filter 4 5 MENU 1 8 1 18 Menu 1 18 Model 1050 padded carrying case 1 6 Model 4288 1 single fixed rack mount kit 1 6 Model 4288 2 side by side rack mount kit 1 6 Model 4288 4 side by side rack mount kit 1 6 Model 8502 trigger link adapter 1 5 Model 8503 DIN to BNC trigger cable 1 5 Models 7007 1 and 7007 2 shielded GPIB cables 1 5 Models 8501 1 and 8501 2 trigger link cables 1 5 MON 1 9 mX 5 3 mX b m X b reciprocal and Logarithmic 5 3 Noise and safety shields 2 5 Open interlock indication 3 13 OPER 3 12 Operation keys 1 8 Optional command words 1 19 Options and accessories 1 4 Overview of this manual 1 2 Package content 1 4 Parameter 7 7 Performance considerations 3 2 Phone number 1 3 Piezoelectric and stored charge effects B 3 POWER 1 8 Powe
12. Offers alternating voltage resistance measurements for resistances from 1090 to 1050 Alternates between OV and user selectable voltage up to 505V At 1 PLC limited to 60 rdgs sec under this condition 2 At 6 PLC 1 standard deviation 100 readings filter off capped input limited to 10 rdgs sec under this condition Measured at analog output with resistive load gt 2kQ Maximum rise time can be up to 25 greater Accuracy does not include output resistance load regulation Rise Time is from OV to full scale voltage increasing magnitude Fall Timeis from full scale voltage to OV decreasing magnitude For capacitive loads add C AV ILimit to Rise Time and C AV 1mA to Fall Time 9 Measured with LO connected to chassis ground Bi vn uo A N REMOTE OPERATION IEEE 488 BUS IMPLEMENTATION SCPI IEEE 488 2 SCPI 1996 0 DDC IEEE 488 1 LANGUAGE EMULATION Keithley Model 486 487 emulation via DDC mode RS 232 IMPLEMENTATION Supports SCPI 1996 0 Baud Rates 300 600 1200 2400 4800 9600 19 2k 38 4k 57 6k Protocols Xon Xoff 7 or 8 bit ASCII parity odd even none Connector DB 9TXD RXD GND AMMETER INPUT CONNECTOR Three lugtriaxial on rear panel ANALOG OUTPUT CONNECTOR Two banana jacks on rear panel VOLTAGE SOURCE OUTPUT CONNECTOR Two banana jacks on rear panel INTERLOCK CONNECTOR 4 pin DIN TRIGGER LINE Available see manual for usage DISPLAY 12 character vacuum fluoresc
13. Use the SAV command to save setups by remote To save the power on setup press CONFIG and then SETUP and select FACT USRO USRI USR2 or GPIB and press ENTER Use the SYST POS command to save the power on setup via remote Restoring setups Press SETUP to display the restore menu then select the setup FACT USRO USRI USR2 or GPIB and press ENTER Use the RCL command to recall setups by remote Restoring factory default setup From the front panel press SETUP select FACT and then press ENTER Use RST to restore GPIB defaults or SYST PRES to restore front panel defaults via remote 1 16 Getting Started Model 6487 User s Manual Table 1 1 D efault settings e ee SYStem PRESet RST Arm Layer CONFIG ARM Arm In Source Event Arm Count Input Trigger Link Line Source Bypass Output Trigger Link Line Output Trigger Buffer STORE Disabled Damping DAMP a 00007 Digital Filter FILT Count Type Display Resolution DIGITS Format byte order GPIB No effect On at factory Address No effect 22 at factory Language No effect SCPI at factory Limit Tests Limit and Limit 2 Disabled HI and LO Values l 1 Log MATH Median Filter FILT Rank M X B MATH Disabled M Value B Value Units Ohms Mode 3 Range AUTO Rate Slow NPLC 6 0 Si or 5 0 50Hz The factory SYStem PRESet and bus RST GPIB defaults are the same Bus settings that are different from facto
14. selected language SCPI or DDC and primary address Examples SCP ADDRE 22 DDG ADDR 22 b R S 232 If RS 232 is the selected interface the instrument will display the baud rate setting For example Ro c292 1 96005 If the FACTory setup is selected as the power on setup the unit is placed in the default reading mode after the communication information is displayed If a setup other than FACTory is selected the configured setup will be displayed For exam ple if the USR 1 setup User Setup 1 is selected USING USRI M odel 6487 User s Manual Getting Started 1 15 D efault settings The Model 6487 can be restored to one of five setup configurations factory default FACT three user saved USRO USRI and USR2 and bus default GPIB As shipped from the factory Model 6487 powers up to the factory default settings Factory default set tings provide a general purpose setup for front panel operation while the bus default GPIB settings do the same for remote operation Factory and GPIB default settings are listed in Table 1 1 The instrument will power up to whichever default setup was saved as the power on setup NOTE Atthe factory the factory default setup is saved into the USRO USRI and USR2 setups Saving user setups To save a user setup configure Model 6487 for the desired measurement application then press SAVE and select the desired setup 0 USRO 1 USRI 2 USR2 Press ENTER to complete the process
15. 6487 User s Manual Range Units Digits Rate and Filters 4 3 U nits Readings can be displayed using engineering ENG units 1 e 1 236 mA or scientific SCI notation 1 e 1 236E 03A To change units press the MENU key select UNITS then press ENTER Select ENG or SCI then press ENTER NOTE The units setting can only be changed from the front panel no remote operation Scientific notation provides more resolution on small values than engineering units Digits The DIGITS key sets display resolution for Model 6487 Display resolution can be set from 3 to 6 digits This single global setting affects display resolution for all measure ment ranges To set display resolution press and release the DIGITS key until the desired number of digits is displayed NOTE The voltage source value will not be displayed in the 6V digit display mode SCPI programming range and digits Table 4 2 SCPI commands range and digits Commands D escription RANG n Select range 0 021 to 0 021 A RANG AUTO lt b gt Enable ON or disable OFF autorange RANG AUTO ULIM n Specify upper range limit for autorange 0 021 to 0 021 A RANG AUTO LLIM n Specify lower range limit for autorange 0 021 to 0 021 A DISP DIG n Set display resolution 4 3 digits to 7 62 digits Programming example range and digits The following command sequence selects the 20mA range and sets display resolution to 3 FE
16. ImA 3mA 20mA From the above readings it is apparent that 3mA is the median middle most reading The number of sample readings used for the median calculation is determined by the selected rank 1 to 5 as follows Sample readings 2x R 1 where R is the selected rank 1 to 5 Note that the median filter throws out the oldest of the ranked values and it is especially useful for noise characterized by unwanted spikes Digital filter Digital filter types An additional filter parameter is type type is either moving or repeating Moving Filter Every time a reading conversion occurs the readings in the stack are averaged to yield a single filtered reading The stack type is first in first out After the stack fills the newest reading conversion replaces the oldest Note that the instrument does not wait for the stack to fill before releasing readings Repeating Filter Takes a selected number of reading conversions averages them and yields a reading It then flushes its stack and starts over 4 6 Range Units Digits Rate and Filters M odel 6487 User s M anual Filter control Front panel Both the median and average filters are controlled by pressing CONFIG then FILT Select MEDIAN or AVERAGE then set appropriate parameters For the MEDIAN selection you can choose ON or OFF and set the RANK For the AVERAGE filter you can choose ON or OFF COUNT MOVING or REPEAT Once the filter is configured you can togg
17. Line ERO niro 1 13 POWESUP SEQUENCe spire 1 14 Default settings ira 1 15 SOIA 1 15 Restoring setups eene 1 15 Restoring factory default setup 1 15 Celia 1 18 SCP PL OO APRA Lia 1 18 Optional command words esses 1 19 CC ni 1 19 Connections Connection fundamentals i 2 2 PAP Ul connector scientist 2 2 Voltage source output connectors 2 2 Maximum input levels sse 2 2 Connecting cables and test leads s 2 3 Basic connections to DUT lione 2 4 Current measurement connections ieri 2 4 Ohms measurement connections ere 2 4 Noise and safety shields iii 2 5 Usi dti 2 6 General purpose test fixture 2 6 Model 8009 resistivity test fixture n 2 6 A RR RR RA RA RT 2 8 Int rlock connections ssa 2 8 Interlock operation 2 8 ANAGSODIPUE LE 2 0 Measurement considerations eeeseeeeeee eene 2 10 Measurements and Sourcing Voltage Measurement overview ariana 3 2 Current mieasuretmellls csc ninni canina enrica 3 2 born d cc 3 2 Performance considerations essere 3 3 Warm up penod 526 AE nsce RR maU Uq Uu ODE ESI RULES 3 3 Voltage offset c
18. Model 6487 User s Manual M easurements and Sourcing Voltage M easurement overview Explains the basic measurement and voltage source capabilities of Model 6487 Performance considerations Covers warm up period voltage offset correction auto zero zero check and zero correct Current measurements Provides a basic procedure to measure current Ohms measurements Covers methods to set up and use the ohms measurement function Voltage source operation Discusses configuring and using the voltage source 3 2 M easurements and Sourcing Voltage M odel 6487 User s Manual Measurement overview Current measurements The basic current measurement capabilities of the Model 6487 are summarized in Table 3 1 Accuracy for each measurement function and range is listed in the specifications Appendix A Table 3 1 Basic current measurement capabilities Reading Range Available R anges Amps 10fA to 21mA 2nA 20nA 200nA 2uA 20uA 200A 2mA and 20mA Voltage source The basic voltage source output capabilities of the Model 6487 are summarized in Table 3 2 Accuracy specifications are shown in Appendix A Table 3 2 Basic voltage source output capabilities Output Range Available Ranges Source 200UV to 505V 10V 50V 500V voltage M odel 6487 User s Manual M easurements and Sourcing Voltage 3 3 Performance consderations Warm up period The Model 6487 can be used within one minute after it
19. adjusting the voltage Step 2 Perform zero correction To achieve optimum accuracy for high resistance measurements it is recommended that you Zero correct the picoammeter before enabling the ohms function To do so make sure that zero check and the 2nA range are selected then press the REL key to perform zero correction MON indicator on Step 3 Select a manual current range or enable auto range Use the manual RANGE keys to select a manual current measurement range or press AUTO to enable auto range When using manual ranging choose an appropriate value based on the voltage source setting and the expected measured resistance I 2 V R M odel 6487 User s Manual M easurements and Sourcing Voltage 3 9 Step 4 Connect the resistance to be measured to the picoammeter Basic connections for ohms measurements are shown in Figure 3 2 Note that both the picoammeter INPUT and the V SOURCE OUTPUT jacks are connected to the resistance under test WARNING A safety shield is advisable whenever measurements are being made with voltages over 30V DC Connections for the safety shield are shown in Figure 3 2 T he metal safety shield must completely surround the noise shield or floating test circuit and it must be connected to safety earth ground using 18 AWG or larger wire Step 5 Select ohms function Press the IIQ key to make sure the ohms function is selected Step 6 Turn on voltage source Press the OPER key to turn on the voltage s
20. is turned on However the instru ment should be turned on and allowed to warm up for at least one hour before use to achieve rated accuracy If the instrument has been exposed to extreme temperatures allow extra time for the internal temperature to stabilize Voltage offset correction Voltage offset correction should be performed periodically to null input amplifier offsets Install the triax shielding cap on the INPUT jack then use the CAL VOFFSET selection in the main MENU To perform correction via remote send CAL UNPR VOFF Autozero To help maintain stability and accuracy over time and changes in temperature the Model 6487 periodically measures internal voltages corresponding to offsets zero and amplifier gains a process known as autozeroing With autozero disabled measurement speed increases up to three times but measurement accuracy will be reduced It is recommended that autozero only be disabled for short periods of time To toggle autozero on or off press the AZERO button When autozero is enabled a colon will be displayed after the reading Via remote send SYST AZER ON for on or SYST AZER OFF Zero check and zero correct Zero check When zero check is enabled on the input amplifier is reconfigured to shunt the input sig nal to low From the front panel enable disable zero check by pressing the ZCHK key ZEROCHK message displayed Refer to Table 3 3 for bus commands Leave zero check enabled when connec
21. key to place the unit in local operation then press the MENU key to access the menu items MENU structure TSTAMP UNITS TEST SNUM LFREQ D escription Reference Provides path to the following calibration submenu items Reference Manual VOFFSET COUNT RUN VSRC RUN DATES UNLOCK Section 16 LOCK and SAVE Timestamp format can be ABSolute or DEL Ta Section 6 Readings can be displayed in ENGineering units or SClentific notation Run display or key tests Reference Manual Section 17 Displays the unit s serial number Line frequency can be manually set to 50 or 60 Hz or Line frequency AUTOmatically set The number after AUTO indicates page 1 13 present detected frequency value SCPI programming SCPI programming information is integrated with front panel operation throughout this manual SCPI commands are listed in tables and additional information that pertains exclusively to remote operation is provided after each table The SCPI tables may refer ence you to other sections of this manual NOTE SCPI tables in this manual are abridged That is they do NOT include most optional command words and query commands See the Section 14 of the Model 6487 Reference Manual for a complete listing of SCPI commands M odel 6487 User s Manual Getting Started 1 19 O ptional command words In order to be in conformance with the IEEE 488 2 standard the Model 6487 accepts optional command words Any command word that is
22. or body movements near the experiment cause fluctuations in the reading Pick up from AC fields can also be detected by observing the picoammeter analog output on an oscilloscope Line frequency signals on the output are an indication that electrostatic interference is present Means of minimiz ing electrostatic interference include 1 Shielding Possibilities include a shielded room a shielded booth shielding the sensitive circuit and using shielded cable The shield should always be connected to a solid connector that is connected to signal low If circuit low is floated above ground observe safety precautions and avoid touching the shield Meshed screen or loosely braided cable could be inadequate for high impedances or in string fields Note however that shielding can increase capacitance in the measuring cir cuit possibly slowing down response time 2 Reduction of electrostatic fields Moving power lines or other sources away from the experiment reduces the amount of electrostatic interference seen in the measurement Magnetic fields A magnetic field passing through a loop in a test circuit will generate a magnetic EMF voltage that is proportional to the strength of the field the loop area and the rate at which these factors are changing Magnetic fields can be minimized by following these guidelines Locate the test circuit as far away as possible from such magnetic field sources as motors transformers and magnets
23. read the associated information very carefully before per forming the indicated procedure The CAUTION heading used in this manual explains hazards that could damage the instrument Such damage may invalidate the warranty U npacking and Inspection Inspection for damage The Model 6487 was carefully inspected electrically and mechanically before shipment After unpacking all items from the shipping carton check for any obvious signs of physi cal damage that may have occurred during transit There may be a protective film over the display lens which can be removed Report any damage to the shipping agent immedi ately Save the original packing carton for possible future shipment Before removing the Model 6487 from the bag observe the handling precautions discussed below Handling precautions Always grasp the Model 6487 by the covers e After removing the Model 6487 from its anti static bag inspect it for any obvious signs of physical damage Report any such damage to the shipping agent immediately When the Model 6487 is not installed and connected keep the unit in its anti static bag and store it in the original packing carton 1 4 Getting Started M odel 6487 User s M anual Package content The following items are included with every Model 6487 order Model 6487 Picoammeter with line cord e Protective triax Shield Cap CAP 31 e 7078 TRX 3 Triax cable e Model 8607 IkV Source Banana cable set e CS 459 4 pin Fema
24. recommended in the user documentation The N symbol on an instrument indicates that the user should refer to the operating instructions located in the manual The A symbol on an instrument shows that it can source or measure 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 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 The CAUTION heading in a manual explains hazards that could damage the instrument Such damage may invalidate the war ranty 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 and fire replacement components in mains circuits including the power transformer test leads and input jacks must be purchased from Keithley Instruments Standard fuses with applicable national safety ap provals 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 selected parts should be purchased only through Keithley Instruments to maintain accuracy and functionality of the product If you are unsure about the a
25. the 10V range the interlock is optional and can be controlled with instru ment programming See Voltage source operation page 3 11 in Section 3 for details on programming the interlock operation for the 10V range Model 6487 User s Manual Connections 2 9 Figure 2 8 Interlock connections Model 6487 Test Fixture WARNING No INTERNAL OPERATOR SERVICABLE PARTS SERVICE BY QUALIFIED PERSONNEL ONLY Qu ema MADE IN A INPUT Xa HETE K Foz E LINE RATING end FUSE LINE B 50 60Hz 630mAT 100 VAC SONE SB 120VAC L X 315mAT 220 VAC SB 240 VAC f see Go j E j l i Interlock Interlock Interlock Connector Cable Connector Test Fixture uh 38 braun Interlock Asserted Switch Output Inhibited with O pen Switch Pin 2 Interlock Analog output The Model 6487 has an analog output on the rear panel The ANALOG OUT provides a scaled inverting 2V output A full scale reading corresponds to 2V output CAUTION Connecting COMMON or ANALOG OUT to earth while floating the input may damage the instrument NOTE Analog outputs will be at same potential as the triax inner shield Connections for using this output are shown in Figure 2 9 For a full scale input i e 2mA on the 2mA range the output will be 2V The 2V analog output signal is not corrected during calibration Gain errors of up to 2 5 may appear at
26. to certain insulating materials 1 e crystalline In some plastics pockets of stored charge cause the material to behave in a similar manner When building test fixtures choose good insulating materials and make connecting struc tures as rigid as possible Make sure there are no mechanical stresses on the insulators B 4 General M easurement Considerations M odel 6487 User s M anual Electrochemical effects Error currents also arise from electrochemical effects when 1onic chemicals create weak batteries on a circuit board These batteries could generate a few nanoamps of current between conductors Ionic contamination may be the result of body oils salts or solder flux The problem is further enhanced by high humidity moisture that decreases insula tion resistance When building test fixtures select insulators that resist water absorption and use the fix ture in a moderate humidity environment Also be sure that all insulators are kept clean and free of contamination Humidity Light Excess humidity can reduce insulation resistance on PC boards and in test connection insu lators Reduction in insulation resistance can of course seriously affect high impedance measurements Also humidity moisture can combine with contaminants to produce offset currents caused by electrochemical effects To minimize the effects of moisture keep humidity to a minimum ideally lt 50 and keep components and connectors in the test system
27. 0 212 8005 ITALY Viale San Gimignano 38 20146 Milano 02 48 39 16 01 Fax 02 48 30 22 74 JAPAN New Pier Takeshiba North Tower 13F 11 1 Kaigan 1 chome Minato ku Tokyo 105 0022 e 81 3 5733 7555 Fax 81 3 5733 7556 KOREA 2FL URI Building 2 14 Yangjae Dong Seocho Gu Seoul 137 888 82 2 574 7778 Fax 82 2 574 7838 NETHERLANDS Postbus 559 4200 AN Gorinchem 0183 635333 Fax 0183 630821 SWEDEN c o Regus Business Centre Frosundaviks All 15 4tr 169 70 Solna 08 509 04 600 Fax 08 655 26 10 TAIWAN 13F 3 No 6 Lane 99 Pu Ding Road Hsinchu Taiwan R O C 886 3 572 9077 Fax 886 3 572 9031 11 02 M odel 6487 Picoammeter Voltage Source U ser s M anual 2002 Keithley Instruments Inc All rights reserved Cleveland Ohio U S A First Printing O ctober 2002 Document Number 6487 900 01 Rev A Manual Print H istory 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 are incorporated into the new Revision of the manual Each new Revision includes a revised copy of this print his
28. 32 V SOURCE OUTPUT 505V PK TO CHASSIS 9 LO C HI INTERLQCK N LINE RATING FUSE LINE 50 60Hz G30mAT 100 VAC 50 VA MAX SB 120 VAC 31 NNAT 220 VAC S 240 VAC 1 INPUT This standard three lug female triax connector is used to connect the signal to be measured to the input of the Model 6487 Figure 1 3 Mates to a three slot male triax connector cable Figure 1 3 Input connector Chassis Ground Input Low Input High M odel 6487 User s Manual Getting Started 1 11 2 CHASSIS This screw terminal is used to connect COMMON to CHASSIS ground via the ground link connector 3 COMMON This standard banana connector can be used as input LO or as the common for the ANALOG OUT Also can be used as a ground link Note that there is a 1k ohm resistance to input LO from the ANALOG OUT common 4 ANALOG OUT This standard banana connector provides a scaled inverting output inverting 2V full scale on all ranges 5 TRIGGER LINK Eight pin micro DIN connector for sending and receiving trigger pulses among connected instru ments Use a trigger link cable or adapter such as Models 8501 1 8501 2 8502 and 8503 6 DIGITAL 1 0 M ale DB 9 connector for digital output lines and component handler signals 7 RS 232 Female D B 9 connector for RS 232 operation U se a straight through not null modem D B 9 shielded cable 8 IEEE 488 Connector for IEEE 488
29. 8 ANALOG OUT DIGITAL 1 0 WITH FRONT WAN EL MENU COO E eM gt v C STS KEITHLEY MADEIN U S A CAT TRIGGER LINK RS 232 V SOURCE OUTPUT amp I 505V PK TO CHASSIS a HI INTERLOCK FUSE LINE 630mAT 100 VAC d SB 120VAC 315mAT 220 VAC SB 240 VAC CAUTION FOR CONTINUED PROTECTION AGAINST FIRE HAZARD REPLACE FUSE WITH SAME TYPE AND RATING LIN E RATING A Z 50 VA MAX Front panel GPIB operation Error and status messages See Appendix B in the Model 6487 Reference Manual for a list of error and status messages associated with IEEE 488 programming GPIB status indicators REM shows when the instrument is in the remote state TALK is on when the instrument is in the talker active state and LSTN is on when the Model 6487 is in the listener active state SRQ shows when the instrument has generated a service request LO CAL key The LOCAL key cancels the remote state and restores local operation of the instrument Pressing the LOCAL key also turns off the REM indicator and returns the display to nor mal if a user defined message was displayed If the unit is in LOCAL not in remote the LOCAL key acts as a configure key see Front panel summary page 1 7 If the LLO Local Lockout command is in effect the LOCAL key is also inoperative 1 4 Remote O peration and Commands M odel 6487 User s Manual Remote commands Genera
30. ANCE GERMANY GREAT BRITAIN INDIA ITALY JAPAN KOREA NETHERLANDS SWEDEN TAIWAN 28775 Aurora Road Cleveland Ohio 44139 e 440 248 0400 Fax 440 248 6168 1 888 K EITHLEY 534 8453 www keithley com Bergensesteenweg 709 B 1600 Sint Pieters Leeuw 02 363 00 40 Fax 02 363 00 64 Yuan Chen Xin Building Room 705 12 Yumin Road Dewai Madian Beijing 100029 8610 8225 1886 Fax 8610 8225 1892 Tietajantie 2 02130 Espoo Phone 09 54 75 08 10 Fax 09 25 10 51 00 3 all e des Garays 91127 Palaiseau C dex 01 64 53 20 20 Fax 01 60 11 77 26 Landsberger Strasse 65 82110 Germering 089 84 93 07 40 Fax 089 84 93 07 34 Unit 2 Commerce Park Brunel Road Theale Berkshire RG7 4AB 0118 929 7500 Fax 0118 929 7519 1 5 Eagles Street Langford Town Bangalore 560 025 INDIA 080 212 8027 e Fax 080 212 8005 Viale San Gimignano 38 20146 Milano 02 48 39 16 01 Fax 02 48 30 22 74 New Pier Takeshiba North Tower 13F 11 1 Kaigan 1 chome Minato ku Tokyo 105 0022 e 81 3 5733 7555 Fax 81 3 5733 7556 2FL URI Building 2 14 Yangjae Dong Seocho Gu Seoul 137 888 82 2 574 7778 Fax 82 2 574 7838 Postbus 559 4200 AN Gorinchem 0183 635333 Fax 0183 630821 c o Regus Business Centre Frosundaviks All 15 4tr 169 70 Solna 08 509 04 600 Fax 08 655 26 10 13F 3 No 6 Lane 99 Pu Ding Road Hsinchu Taiwan R O C 886 3 572 9077 Fax 886 3 572 9031 Copyright 2002 Keithl
31. B RS 232 and trigger link cables and adapters Models 7007 1 and 7007 2 shielded GPIB cables Connects the Model 6487 to the GPIB bus using shielded cables and connectors to reduce electromagnetic interference EMI Model 7007 1 is Im long Model 7007 2 is 2m long Model 7009 5 shielded R S 232 cable Connects the Model 6487 to the RS 232 inter face using shielded cable and connectors to reduce electromagnetic interference EMI Model 7009 5 is 5 ft long Models 8501 1 and 8501 2 trigger link cables Connects the Model 6487 to other instruments with Trigger Link connectors e g Model 7001 Switch System Model 8501 1 is Im long Model 8501 2 is 2m long M odel 8502 trigger link adapter Lets you connect any of the six trigger link lines of the Model 6487 to instruments that use the standard BNC trigger connectors Model 8503 DIN to BNC trigger cable Lets you connect trigger link lines one Voltmeter Complete and two External Trigger of the Model 6487 to instruments that use BNC trigger connectors Model 8503 is Im long 1 6 Getting Started M odel 6487 User s M anual Rack mount kits M odel 4288 1 single fixed rack mount kit Mounts a single Model 6487 in a standard 9 inch rack M odel 4288 2 side by side rack mount kit Mounts two instruments Models 182 428 486 487 2000 2001 2002 2010 2400 2410 2420 2430 6430 6485 6487 6517A 7001 side by side in a standard 19 inch rack M odel 4288 4 s
32. GPIB operation U se a shielded cable such as Models 7007 1 and 7007 2 9 V SOURCE OUTPUT HI This standard banana connector provides HI connection to the 6487 s voltage source WARNING Hazardous voltage may be present on the rear panel V SOURCE OUTPUT terminals when the front panel operate indicator is on CAUTION Do not connect external sources to the 6487 voltage source E xternal sources may damage the 6487 voltage source 10 V SOURCE OUTPUT LO This standard banana connector provides LO connection to the 6487 s voltage source CAUTION Do not connect external sources to the 6487 voltage source E xternal sources may damage the 6487 voltage source 11 INTERLOCK Thisinterlock connector provides connection of the 6487 s voltage source with an interlock connector on a test fixture 12 Power Module Contains the AC line receptacle and power line fuse The instrument can be configured for line volt ages of 115V and 230VAC nominal at line frequencies of 50 or 60Hz automatically and over the bus Changing line voltages requires changing fuses Getting Started M odel 6487 User s Manual Voltage source The Model 6487 voltage source can source up to 505V DC and is used for the ohms function See Basic connections to DUT page 1 4 in Section 2 for full details on voltage source operation Analog output The Model 6487 has an analog output on the rear panel The ANALOG OUT provides a scaled inverting 2V output A full s
33. HK key toggles zero check on and off Step 3 Perform zero correction To achieve optimum accuracy for low current measurements it is recommended that you Zero correct the picoammeter To do so make sure the 2nA range is selected then press the REL key to perform zero correction MON indicator on Step 4 Select a manual measurement range or enable auto range Use the manual RANGE keys to select a manual measurement range or press AUTO to enable auto range With auto range enabled the instrument will automatically go to the most sensitive range to make the measurement See Section 4 for details on range 3 6 M easurements and Sourcing Voltage M odel 6487 User s Manual Step 5 Connect the current to be measured to the picoammeter Basic connections for measurements are shown in Figure 3 1 WARNING A safety shield is advisable whenever floating measurements are being made Connections for the safety shield are shown in Figure 3 1 T he metal safety shield must completely surround the noise shield or float ing test circuit and it must be connected to safety earth ground using 18 AWG or larger wire NOTE When not making floating measurements it is recommended that you ground measurement LO at only one place in the circuit such as with the ground link connection on the rear panel of the 6487 See Ground loops page B 2 Fundamental information on making connections to the picoammeter input is provided in Section 2 Step 6 Di
34. HLEY Service Form Model No Serial No Date Name and Telephone No Company List all control settings describe problem and check boxes that apply to problem LJ Intermittent Q Analog output follows display Q Particular range or function bad specify Q IEEE failure Q Obvious problem on power up Q Batteries and fuses are OK Q Front panel operational U All ranges or functions are bad Q Checked all cables Display or output check one Q Drifts Q Unable to zero Q Unstable Q Overload U Will not read applied input Q Calibration only Q Certificate of calibration required Q Data required attach any additional sheets as necessary Show a block diagram of your measurement including all instruments connected whether power is turned on or not Also describe signal source Where is the measurement being performed factory controlled laboratory out of doors etc What power line voltage is used Ambient temperature E Relative humidity Other Any additional information If special modifications have been made by the user please describe Be sure to include your name and phone number on this service form Specifications are subject to change without notice All Keithley trademarks and trade names are the property of Keithley Instruments Inc All other trademarks and trade names are the property of their respective companies KEITHLEY K eithley Instruments I nc Sales Offices BELGIUM CHINA FINLAND FR
35. M etal Noise Shield M etal Noise Shield HI M etal Safety yo DUT casi out INPUT e dii NOS diri Safety LO Earth LO Ground A Noise Shield B Safety Shield U sing a test fixture Whenever possible use a shielded low leakage test fixture to make precision measurements and for safety when high voltages gt 30V are used General purpose test fixture A general purpose test fixture is shown in Figure 2 6 This test fixture will accommodate a variety of connection requirements Model 8009 resistivity test fixture This test fixture allows volume resistivity in the range from 10 to 10 8Q cm and surface resistivity in the range from 10 to 10 0 sq For typical connections to the Model 6487 refer to Figure 2 7 Model 6487 User s Manual Connections 2 7 Figure 2 6 General purpose test fixture connections Metal Chassis To Voltage A e Insulated Source e oer ce 9 1 DUT To 6487 Input e To 6487 e COMMON o M etal G uard Plate Safety Earth Ground A Banana Jacks 3 Lug Female Triax Connector Figure 2 7 Typical connections for measurements using the Model 8009 test fixture 6517 ILC 3 Safety Interlock Cable M odel 6487 WARNING no INTERNAL OPERATOR SERVICABLE PARTS SERVICE BY QUALIFIED PERSONNEL ONLY Model 8009 MADE I US A DIGITAL I O CHANUE HEE nese C CATI LID INTERLOCK V SOURCE OU
36. MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE THE REMEDIES PROVIDED HEREIN ARE BUYER S SOLE AND EXCLUSIVE REMEDIES NEITHER KEITHLEY 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 DAM AGES 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 KEI I HLEY Keithley Instruments Inc 28775 Aurora Road Cleveland Ohio 44139 440 248 0400 Fax 440 248 6168 1 888 K EITHLEY 534 8453 www keithley com Sales Offices BELGIUM Bergensesteenweg 709 e B 1600 Sint Pieters Leeuw 02 363 00 40 Fax 02 363 00 64 CHINA Yuan Chen Xin Building Room 705 12 Yumin Road Dewai Madian Beijing 100029 e 8610 8225 1886 Fax 8610 8225 1892 FINLAND Tiet j ntie 2 02130 Espoo Phone 09 54 75 08 10 Fax 09 25 10 51 00 FRANCE 3 all e des Garays 91127 Palaiseau C dex 01 64 53 20 20 e Fax 01 60 11 77 26 GERMANY Landsberger Strasse 65 82110 Germering 089 84 93 07 40 Fax 089 84 93 07 34 GREAT BRITAIN Unit 2 Commerce Park Brunel Road Theale Berkshire RG7 4AB 0118 929 7500 Fax 0118 929 7519 INDIA 1 5 Eagles Street Langford Town Bangalore 560 025 INDIA e 080 212 8027 Fax 08
37. R VOLT ILIM Current Set current limit 25uA 25014 2 5mA or 25mA SOUR VOLT STAT lt b gt Turn voltage source output ON or OFF READ Trigger and return reading s Zero correct and zero check commands not included See Table 3 3 Model 6487 User s Manual M easurements and Sourcing Voltage 3 11 Programming example ohms measurements The following command sequence will perform one zero corrected resistance measurement RST FORM ELEM READ UNIT SYST ZCH ON RANG 2e 9 INIT SYST ZCOR ACO O SYST ZCOR ON RANG AUTO ON SOUR VOLT SOUR VOLT 10 SOUR VOLT ILIM 2 5e 3 SENS OHMS ON SOURs VOLT SIAT ON SYST ZCH OFF READ Voltage source operation Configuring the voltage source Return 6487 to GPIB defaults Measurement units elements only Enable zero check Select the 2nA range Trigger reading to be used as zero correction Use last reading taken as zero correct value Perform zero correction Enable auto current range Select 10V source range Set voltage source output to 10V Set current limit to 2 5mA Enable ohms function Put voltage source in operate Disable zero check Trigger and return one reading Press CONFIG then OPER to set the voltage source mode You will first be prompted to choose DC or SWEEP mode Select DC for normal operation See Section 6 for details on sweeps After the mode is selected the display shows a full resolution value of the voltage source with th
38. ST Restore Rol derteultbss RANG 0 02 Set to 20mA range DISP DIG 4 t Set display resolution to 3 172 dliglts 4 4 Range Units Digits Rate and Filters Model 6487 User s Manual Rate The RATE key selects the integration time of the A D converter which is the period of time the input signal is measured The integration time affects the amount of reading noise as well as the ultimate reading rate of the instrument The integration time is speci fied in parameters based on a number of power line cycles NPLC where 1 PLC for 60Hz is 16 67msec 1 60 and 1 PLC for 50Hz and 400Hz is 20msec 1 50 The rate setting is global for all ranges Therefore it does not matter what range is presently selected when you set rate To select the rate either press the RATE key to select SLOW 6 PLC 60Hz 5 PLC 50Hz MED 1 PLC or FAST 0 1 PLC or press CONFIG and then RATE and then enter the desired number of PLCs 0 01 to 60 60Hz 0 01 to 50 50Hz To set the rate by remote send NPLC plc with an allowable range or 0 01 to 60 60Hz or 0 01 to 50 50Hz Damping Filters High capacitance seen at the input will increase reading noise This capacitance can be attributed to a long input cable or to the capacitance of the source or a combination of both Enabling damping analog filtering will reduce noise caused by high capacitance for current measurements However damping will also slow down the response of the measuremen
39. TPUT 505V PK TO CHASSIS O n m L LINE RATING Z O X FUSE LINE VAC LE 50 VA MAX SATTSAD OURCE gt Warning Connect fixture ground to safety earth 8607 Banana Plug Cables ground using safety ground wire supplied with the test fixture 2 8 Connections Model 6487 User s Manual Interlock The Model 6487 has a built in interlock that works in conjunction with the voltage source The interlock prevents the voltage source from being placed in operate on the 50V and 500V ranges and optionally on the 10V range to assure safe operation Interlock connections Figure 2 8 shows interlock connections and the pin diagram of the INTERLOCK connec tor Typically the INTERLOCK connector is connected to the same type of connector on the test fixture A normally open switch is connected to pins 1 and 2 of the INTERLOCK connector as shown When the switch is open the interlock is asserted and the voltage source cannot be placed in operate on the 50V or 500V voltage source ranges and option ally for the 10V range WARNING If the voltage source was operating when the interlock is asserted the voltage source will change to a high impedance state possibly leaving charged DUT capacitance Interlock operation The interlock is always operational for the 50V and 500V voltage source ranges To enable the voltage source output pins 1 and 2 of the INTERLOCK connector must be shorted together For
40. adings It also stores overflow readings Each reading includes the voltage source value and a timestamp The timestamp for each reading is referenced to the time the measure store process is started In addition recalled data includes statistical information maximum minimum peak to peak average and standard deviation The buffer fills with the specified number of readings and stops Readings are placed in the buffer after any filters and or math operations have been performed Math operations include relative mX b m X b LOG or limits Buffered data is overwritten each time the storage operation is selected The data is volatile it is not saved through a power cycle Measurement function changes are permissible during the storage process Note however that the statistics will be based on the readings of the different measurement functions To store readings set up the instrument for the desired configuration then press CONFIG followed by STORE Set the number of readings to store 1 3000 and press ENTER Press the STORE key to start data storage The asterisk annunciator turns on to indicate that the data storage operation is active To abort storage while active press EXIT To view stored readings and buffer statistics press RECALL then use the RANGE and cursor keys to navigate through the reading numbers and buffer statistics reading values voltage source values and timestamps Use the RANGE keys to scroll through sta
41. afety do not touch the product test cables or any other instruments while power is applied to the circuit under test ALWAYS remove power from the entire test system and discharge any capacitors before connecting or disconnecting ca 5 02 bles or jumpers installing or removing switching cards or making internal changes such as installing or removing jumpers Do not touch any object that could provide a current path to the common side of the circuit under test or power line earth ground AI ways 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 equipment may be impaired Do not exceed the maximum signal levels of the instruments and accessories as defined in the specifications and operating in formation and as 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 fire 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 If or A is present connect it to safety earth ground using the wire
42. alue When the MAXimum parameter is used the instrument is programmed to the largest allowable value Angle brackets lt gt Used to denote a parameter type Do not include the brackets in the program message 1 8 Remote O peration and Commands M odel 6487 User s Manual A Specifications 6487 Picoammeter Specifications TYPICAL ANALOG 5 2 DIGIT ACCURACY 1YR 1 RISE TIME 10 TO 90 DEFAULT RDG OFFSET TYPICAL DAMPING RANGE RESOLUTION 18 28 C 0 70 RH RMS NOISE OFF ON 2 nA 10 fA 0 3 400 fA 20 fA 4ms 80 ms 20 nA 100 fA 0 2 1pA 20 fA 4ms 80 ms 200 nA 1pA 0 15 10 pA 1pA 300 us lms 2 uA 10 pA 0 15 100 pA 1pA 300 us lms 20 uA 100 pA 0 1 1nA 100 pA 110 us 110 us 200 uA 1nA 0 1 10nA 100 pA 110 us 110 us 2mA 10 nA 0 1 96 100 nA 10nA 110 us 110 us 20mA 100 nA 0 1 1lpA 10nA 110 us 110 us TEMPERATURE COEFFICIENT 0 18 C amp 28 50 C For each C add 0 1 x rdg offset to accuracy Spec INPUT VOLTAGE BURDEN lt 200UV on all ranges except ImV on 20mA range MAXIMUM INPUT CAPACITANCE Stable to 10nF on all nA ranges and 2uA range 1uF on 204A and 200A ranges and on mA ranges MAXIMUM CONTINUOUS INPUT VOLTAGE 505 VDC NMRR 50 or 60Hz 60dB ISOLATION Ammeter Common or Voltage Source to chassis Typically 21x10H0 in parallel with lt nF MAXIMUM COMMON MODE VOLTAGE Between Chassis and Voltage Source or Ammeter 505 VDC MAXIMUM VOLTAGE BETWEEN VOLTAGE SOURCE AND AMMETER
43. anel relai ve ssi 5 2 SCPI programming relative i 5 2 mX b m X b reciprocal and Logarithmic 5 3 mX b and M XAD sss 5 3 Logan eR RI 5 3 Configuring math functions 5 4 SCPI programming mX b m X b and log 5 4 Buffer and Sweeps Buffer operations enne nennen nnn 6 2 vr M M 6 2 ler 6 2 BUI 6 2 Cdl 6 3 BUS sla 6 3 SCPI programming buffer i 6 4 Propsrominup example iris 6 4 Voltage SWEEPS ECL E arane eakaid 6 5 Fionde 6 5 SCPI programming SWEEPS 6 5 Programming example iii 6 6 Remote O peration and Commands Selecting and configuring an interface e 7 2 las Rr 7 2 Connections TR 7 2 Front panel GPIB operation n 7 3 Remote commands set eroscastonencocubsostuancondauaxeoen sean coetu Up amt to 7 4 General DUS commands suoi oci io ire tubes tone data i ooo das 7 4 Common commands 7 4 Signal oriented commands eese 7 5 SCPI command subsystems essen 7 6 Programming syntax ooxssssdcoessensidesesausils sets Micneecebube nri baduds 7 6 Specifications General Measurement Consderations Measurement considerations sss B 2 Ground loops
44. ange Disable zero check Trigger and return one reading 3 8 M easurements and Sourcing Voltage M odel 6487 User s Manual O hms measurements O verview To measure ohms with the Model 6487 you must set up the voltage source to the desired range value and current limit see Voltage source operation page 3 11 choose an appropriate current measurement range or use auto range and enable the ohms function With the ohms function enabled the Model 6487 calculates the measured resistance from the voltage source value and the measured current R V I When setting up the voltage source choose as high a voltage value as possible for maximum current keeping in mind such factors as the power dissipation and voltage coefficient of the resistance being tested NOTE The ohms measurements can be made using either the DC or alternating voltage modes Only the DC mode is used in this manual See Section 5 of the Model 6487 Reference Manual for information on the alternating voltage mode Procedure WARNING Always turn off the Model 6487 s voltage source before changing volt age source connections to avoid a possible shock hazard Perform the following steps to measure resistance Step 1 Set up voltage source Press either of the V SOURCE adjustment keys then use a manual RANGE key to set the voltage source range Set the voltage and current limit to the desired values You can skip the current limit prompt by pressing EXIT after
45. cale reading corresponds to 2V output See Analog output page 1 9 in Section 2 for full details on analog output operation Digital I O The Model 6487 s Digital I O port is a male DB 9 connector located on the rear panel The four active low digital output lines and one input line are used to control external circuitry For detailed connection and usage information refer to Section 8 of the Model 6487 Reference Manual Display Readings can be displayed in engineering units or scientific notation Annunciators indi cate various states of operation See Front panel summary page 1 7 for a complete list ing of display annunciators The normal display also includes the voltage source value on the right NOTE Changing the display resolution is not allowed if displaying readings in scien tific notation The DISP key can be used to turn the display on or off The Display and Keys Test allows you to test display digit segments and annunciators and check the functionality of front panel keys These tests are accessed through the MENU Status and error messages Status and error messages are displayed momentarily During operation and programming you will encounter a number of front panel messages Typical messages are either of status or error variety as listed in Appendix B of the Model 6487 Reference Manual M odel 6487 User s Manual Getting Started 1 13 Power up Line power connection Follow the procedure below to co
46. clean Some components such as semiconductor junctions and MOS capacitors on semiconduc tor wafers are excellent light detectors Consequently these components must be tested in a light free environment While many test fixtures provide adequate light protection oth ers may allow sufficient light penetration to affect the test results Areas to check for light leaks include doors and door hinges tubing entry points and connectors or connector pan els With this in mind the Model 6487 display may be turned off by sending the DISP ENAB OFF command 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 effects of such electrostatic action are not noticeable because low impedance levels allow the induced charge to dissipate quickly However the high impedance levels of many mea surements do not allow these charges to decay rapidly and erroneous or unstable readings may result These erroneous or unstable readings may be caused in the following ways 1 DC electrostatic field can cause undetected errors or noise in the reading 2 AC electrostatic fields can cause errors by driving the input preamplifier into saturation or through rectification that produces DC errors Model 6487 User s Manual General M easurement Considerations B 5 Electrostatic interference is first recognizable when hand
47. e Avoid moving any part of the test circuit within the magnetic field e Minimize the loop area by keeping leads as short as possible and twisting them together Electromagnetic Interference EMI The electromagnetic interference characteristics of the Model 6487 comply with the elec tromagnetic compatibility EMC requirements of the European Union as denoted by the CE mark However it is still possible for sensitive measurements to be affected by exter nal sources In these instances special precautions may be required in the measurement setup Sources of EMI include e Radio and TV broadcast transmitters Communications transmitters including cellular phones and handheld radios Devices incorporating microprocessors and high speed digital circuits e Impulse sources as in the case of arcing in high voltage environments B 6 General M easurement Considerations Model 6487 User s Manual The effect on instrument performance can be considerable if enough of the unwanted sig nal is present The effects of EMI can be seen as an unusually large offset or in the case of impulse sources erratic variations in the displayed reading The instrument and experiment should be kept as far away as possible from any EMI sources Additional shielding of the instrument experiment and test leads will often reduce EMI to an acceptable level In extreme cases a specially constructed screen room may be required to sufficiently attenuate the
48. e left most position highlighted for editing If you do not wish to change the mode you can jump right to this voltage edit display by pressing either V SOURCE adjustment arrow The lt and b arrows are used to select the digit being edited and the V SOURCE A and w arrows change the value The RANGE A and WV arrows change the voltage source range and indicate the range selected Note that the V SOURCE A and w keys will operate in the same manner as the RANGE A and V keys if they are not being used to change the voltage source value Voltage values are changed immediately from this configuration by pressing the arrow key The digits will not increment beyond the maximum voltage for the selected range After the voltage value and range are selected press EXIT to return to normal readings dis play or press ENTER to advance to the current limit display The current limit display offers different choices depending on the source range refer to Table 3 6 Pressing ENTER or EXIT from this display returns you to the normal readings display 3 12 M easurements and Sourcing Voltage M odel 6487 User s Manual Table 3 6 Voltage source current limits Source R ange Selectable C urrent Limit 10 0000V Range 25uA 250uA 50 000V Range 25uA 250uA 500 00V Range 25uA 250uA Sourcing voltage CAUTION Do not connect external sources to the 6487 voltage source E xternal sources may damage the 6487 voltage source Turning source on and
49. e math on or off The MATH annunciator will turn on to indicate that the math function is enabled SCPI programming mX b m X b and log Table 5 2 SCPI commands mX b m X b and log CALC FORM name Select math function MXB REC or LOGIO CALC KMAT MMF n Set M for mX b and m X b 9 99999e20 to 9 99999e20 CALC KMAT MBF n Set B for mX b and m X b 9 99999e20 to 9 99999e20 CALC KMAT MUN name Set units for mX b or m x b 1 character A Z Q V T CALC STAT b Enable or disable the selected math function CALC DATA Returns all CALC results triggered by the INIT CALC DATA LAT Returns only the latest CALC reading Programming example mX b This command sequence performs a single mX b calculation and returns the result ROT Restore RST defaults CALC FORM MXB Select mX b calculation CALC KMAT MMF 2e 3 set scale factor M to 26 3 CALC KMAT MBF 5e 4 Set offset B to 5e 41 CALC STAT ON Enable calculation SYST ZCH OFF Disable zero check INIT Perform one measurement and calculate mX b CALC DATA Request mX b result Buffer and Sweeps Buffer operations Explains how to store and recall readings including buffer statistics e Voltage sweeps Discusses how to generate sweeps using the voltage source 6 2 Buffer and Sweeps M odel 6487 User s Manual Buffer operations Store Recall The Model 6487 has a buffer to store from one to 3 000 re
50. el value is the same for all measurement ranges For example a Rel value of 1E 6 is ILLA on the 2LLA range It is also IUA on the 204A range and the 200UA range Note changing ranges does not disable Rel Front panel relative From the front panel there are two ways to set the Rel value You can either use the input reading as the Rel value or you can manually key in the Rel value To use the present reading first disable zero check display the reading then press REL The REL annunciator will turn on and subsequent readings will be the difference between the actual input and the Rel value To disable relative press REL again while zero check is disabled To enter a reading press CONFIG then REL enter the desired value then press ENTER Relative will be enabled after you enter the value NOTE Separate Rel values are stored for the amps and ohms functions SCPI programming relative Table 5 1 SCPI commands relative null Commands D escription CALC2 FEED name Specify reading to Rel SENS or CALCI CALC2 NULL ACQ Use input signal as Rel value CALC2 NULL OFFS Rel Specify Rel value 9 999999e20 to 9 999999e20 CALC2 NULL STAT b Enable ON or disable OFF Rel CALC2 DATA Return Rel ed readings triggered by INIT CALC2 DATA LAT Return only the latest Rel ed reading INIT Trigger one or more readings M odel 6487 User s Manual Relative mX b m X b reciprocal and log 5 3 Programming example
51. elect timestamp format ABS or DELT TRAC DATA Read all readings in buffer FORM ELEM lt list gt Specify data elements for TRAC DATA response message READ UNIT VSO TIME and STAT CALC3 FORM lt name gt Select buffer statistic MIN MAX MEAN SDEV or PKPK CALC3 DATA Read the selected buffer statistic Programming example The following command sequence stores 20 readings into the buffer and then calculates the mean average on the buffer readings Select data elements RST Return 6487 to RST defaults FORM ELEM READ TIME Select reading and timestamp Store and Recall Readings TRIG COUN 20 Set trigger model to take to 20 readings TRAC POIN 20 Set buffer size to 20 TRAC FEED SENS Store raw input readings TRAC FEED CONT NEXT Start storing readings SYST ZCH OFF Turn off zero check INIT Trigger readings TRAC DATA Request all stored readings Acquire Mean Statistic for Buffer Readings CALC3 FORM MEAN Select mean statistic CALC3 DATA Request mean statistic M odel 6487 User s Manual Buffer and Sweeps 6 5 Voltage sweeps The Model 6487 voltage source can be used to generate voltage sweeps from a start volt age to a stop voltage at discrete step voltages The Model 6487 stores readings in the buffer for later recall one set of readings per voltage step Front panel sweeps To generate sweeps from the front panel press CONFIG then OPER select SWEEP then press ENTER A
52. enclosed in brackets 1s optional and does not have to be included in the program message Programming examples in this manual use the short form and do not include optional command words for simplicity Query commands Most command words have a query form A query command is identified by the question mark that follows the command word A query command requests queries the pro grammed status of that command When a query command is sent and Model 6487 is addressed to talk the response message is sent to the computer 1 20 Getting Started Model 6487 User s Manual Connections Connection fundamentals Covers fundamental information about connecting test circuits to the picoammeter Basic connections to DUT Details connecting test circuits to the picoammeter for both current and ohms measurements U sing a test fixture Discusses using general test fixtures as well as the Model 8009 test fixture Interlock Provides information on using the interlock which must be used to optimize safety Analog output Covers analog output connections and discusses considerations when using the analog output M easurement considerations Summarizes considerations that could affect overall measurement accuracy 2 2 Connections M odel 6487 User s M anual Connection fundamentals The following provides important fundamental information on input connections to the Model 6487 Typical connection drawings are provided
53. ent DIGITAL FILTER Median and averaging selectable from 2 to 100 readings RANGING Automatic or manual AUTORANGING TIME lt 250ms analog filter off 1PLC OVERRANGE INDICATION Display reads OVRFLOW CONVERSION TIME Selectable 0 01 PLC to 60 PLC 50PLC under 50Hz operation Adjustable from 200us to 1s READING RATE To internal buffer 1000 readings second To IEEE 488 bus 900 readings second 2 BUFFER Stores up to 3000 readings PROGRAMS Provide front panel access to IEEE address choice of engineering units or scientific notation and digital calibration EMC Conforms with European Union Directive 89 336 EEC EN61326 1 SAFETY Conforms with European Union Directive 73 23 EEC EN61010 1 CAT ENVIRONMENT Operating 0 50 C relative humidity 70 non condensing up to 35 C Above 35 C derate humidity by 3 for each C Storage 10 C to 65 C WARM UP 1 hour to rated accuracy See manual for recommended procedure POWER 100 120V or 220 240V 50 60Hz 50VA PHYSICAL Case Dimensions 90mm high x 214mm wide x 369mm deep 3 in x 8 in x 14 e in Working Dimensions From front of case to rear including power cord and IEEE 488 connector 394mm 15 5 inches NET WEIGHT 4 7 kg 10 3 Ibs Notes 1 0 01 PLC digital filters off front panel off auto zero off Binary transfer mode IEEE 488 1 3 Measured from trigger in to meter complete Specifications are subject to change without
54. ey Instruments Inc Printed in the U S A 11 02
55. gramming example voltage The following command sequence will output 5V on the 10V range with a 2 5mA limit Rol i SOUR VOLT RANG 10 i SOUR VOLT 5 i SOUR VOLT ILIM 2 5e 3 i SOUR VOLT STAT ON i Return 6487 to GPIB defaults Select 10V source range Set voltage source output to 5 Set current limit to 2 5mA Put voltage source in operate 3 14 M easurements and Sourcing Voltage M odel 6487 User s Manual Range Units Digits Rate and Filters Range units and digits Provides details on measurement range reading units and display resolution selection Includes the SCPI commands for remote operation Rate Provides details on reading rate selection Includes the SCPI commands for remote operation Damping Provides details on damping rate selection Includes the SCPI com mand for remote operation Filters Explains how to configure and control the digital and median filters Includes the SCPI commands for remote operation 4 2 Range Units Digits Rate and Filters M odel 6487 User s M anual Range units and digits Range The ranges for current measurements are listed in Table 4 1 Table 4 1 Measurement ranges LM TM IM 2nA 2UA 2mA ee RR ona 20088 The full scale readings for every measurement range are 5 over range For example on the 20LA range the maximum input current is 21uA Input values that exceed the maxi mum readings cause the overflow message OVRFLOW to be displayed
56. he internal temperature of Model 6487 when it was last calibrated SCPI programming zero check and zero correct Table 3 3 SCPI commands zero check and zero correct Commands D escription SYST ZCH b Enable ON or disable OFF zero check SYST ZCOR b Enable ON or disable OFF zero correct SYST ZCOR ACQ Acquire zero correct value INIT Trigger a reading M odel 6487 User s Manual M easurements and Sourcing Voltage 3 5 Current measurements Procedure WARNING Themaximum safe voltage between picoammeter LO and chassis ground common mode voltage is 505V T he M odel 6487 does not internally limit the LO to chassis voltage E xceeding 505V can create a shock hazard If it is possible for the DUT or external supply to present more than 505V to the input HI itis imperative that the connection between input LO and the external voltage source be sufficiently low impedance and capable of carrying the short circuit current of the source in order that the LO not exceed 505V CAUTION Themaximum input voltage and current to Model 6487 is 505V peak and 21mA E xceeding either of these values may cause damage to the instrument that is not covered by the warranty Perform the following steps to measure current Step 1 Select current function Press the IIQ key to make sure the current function is selected Step 2 Enable zero check Zero check should always be enabled before making connection changes The ZC
57. hree user GPIB defaults and factory defaults can be saved and recalled e mX b m X b reciprocal for resistance calculations and log10 These calculations provide mathematical manipulation of readings Section 5 M odel 6487 User s Manual Getting Started 1 7 e Relative Null offsets or establish baseline values Section 5 Buffer Store up to 3000 points of data in the internal buffer Section 6 e Limits Set up to two stages of high and low reading limits to test devices see Section 8 of the Reference Manual Digital I O port Four output lines and one input line to control external cir cuitry as an interface between limit tests and component handler See Section 8 of the Reference Manual e Remote interface Model 6487 can be controlled using the IEEE 488 interface GPIB or the RS 232 interface Section 7 e Voltage source Internal 500V voltage source is also used for ohms function Section 3 e GPIB programming language When using the GPIB the instrument can be programmed using the SCPI or DDC programming language Front and rear panel familiarization Front panel summary The front panel of Model 6487 is shown in Figure 1 1 Figure 1 1 Front panel N KEITHLEY 7 6487 PICOAMMETER VOLTAGE SOURCE VOLTAGE V oUUH SOURCE cm Zum d dm O AE OPERATE e a RANGE N 2 POWER RANGE ad E Q SAVE SETUP AZERO DAMP EXIT ENTER V
58. ide by side rack mount kit Mounts Model 6487 and a 5 25 inch instrument Models 195A 196 220 224 230 263 595 614 617 705 740 775A 6512 side by side in a standard 19 inch rack Carrying case M odel 1050 padded carrying case A carrying case for Model 6487 Includes handles and shoulder strap U ser s manual If an additional Model 6487 user s manual is required order the manual package The Keithley part number for the manual package is 6487 900 00 The manual package includes a user s manual and any pertinent addenda Additional references While reading this document you may find it helpful to consult the following documenta tion for reference M odel 6487 R eference M anual Supplied in electronic format on the Product Informa tion CD ROM included with your shipment this document provides in depth information on Model 6487 operation as well as performance verification calibration and routine maintenance procedures Check www keithley com for details Low Level Measurements handbook Keithley s guide for effective low current low voltage and high impedance measurements Check www keithley com for details Features The Model 6487 is a high performance picoammeter capable of measuring current and resistance Section 2 contains details on its measurement capabilities Connection funda mentals page 2 2 Features of Model 6487 Picoammeter include Setup storage Five instrument setups t
59. in Basic connections to DUT page 2 4 More detailed connections for specific measurements are in Section 3 Input connector The rear panel INPUT connector is a 3 lug female triax connector Figure 2 1 Make con nections using a male terminated triax cable Figure 2 1 Triax input connector Chassis Ground Input Low Input High Voltage source output connectors The rear panel V SOURCE OUTPUT HI and LO connectors see Figure 1 2 in Section 1 are used to connect the voltage source to the DUT The voltage source is primarily used for ohms measurements See Ohms measurement connections page 2 4 for details Maximum input levels The maximum input levels to the Model 6487 are summarized in Figure 2 2 Model 6487 User s Manual Connections 2 3 WARNING Themaximum safe voltage between the voltage source or ammeter common and chassis ground common mode voltage is 505V peak E xceeding this voltage can create a shock hazard Figure 2 2 Maximum input levels Input HI Max Continuous Input 505V Peak Input LO O 505V Peak 505V Peak Chassis Ground nad Connecting cables and test leads When making precision measurements you should always use low noise triax cables for INPUT connections As a general rule always use the shortest possible cable for measure ments When using the voltage source the test leads must be rated for 505 V minimum and should include safety sheaths See In
60. interface To configure the GPIB IEEE 488 interface press CONFIG then COMM when the GPIB interface is selected then select the primary address 0 30 default 22 and language SCPI DDC or 488 1 The primary address must be the same as that specified in the computer program but be sure to avoid address conflicts Use the SCPI language setting for most applications See the Model 6487 Reference Manual for information on the DCC and 488 1 programming languages RS 232 interface To configure the RS 232 interface press CONFIG then COMM when the RS 232 inter face 1s selected then set baud rate data bits parity terminator and flow control To assure proper operation be sure that interface parameters are the same as those used by the con trolling computer Connections GPIB connections With the power off connect a shielded GPIB cable Keithley Model 7007 between the rear panel IEEE 488 connection Figure 7 1 and the computer bus connector RS 232 connections With the power off connect the Model 6487 RS 232 connector Figure 7 1 to the com puter serial port using a straight through shielded RS 232 cable terminated with DB 9 connectors Keithley Model 7009 Do not use a null modem cable M odel 6487 User s Manual Remote O peration and Commands 1 3 Figure 7 1 IEEE 488 and RS 232 connector locations RS 232 IEEE 488 WARNING NoO INTERNAL OPERATOR SERVICABLE PARTS SERVICE BY QUALIFIED PERSONNEL ONLY IEEE 48
61. is calculated as follows Where Xiis a stored reading n is the number of stored readings e The STD DEV value is the standard deviation of the buffered readings Standard deviation is calculated as follows Where X is a stored reading n is the number of stored readings Avg is the mean of the buffer readings NOTE _ If any readings stored in the buffer are the result of an overflow or overvoltage condition the buffer statistics calculation will not be performed Buffer recall via front panel operation will show a series of dashes in place of the requested buffer statistics value In remote operation the corresponding buffer statistics will be represented by the value 9 91637 6 4 Buffer and Sweeps M odel 6487 User s Manual SCPI programming buffer NOTE When programming the buffer via remote the trigger count set with the TRIG COUN command should normally equal the number of buffer readings to store set with TRAC POIN See Section 7 of the Model 6487 Reference Manual for details on triggering Table 6 1 SCPI commands buffer TRAC CLE Clear readings from buffer TRAC FREE Query bytes available and bytes in use TRAC POIN n Specify number of readings to store 1 to 3000 TRAC POIN ACT Returns number of readings actually stored in buffer TRAC FEED name Select source of readings for buffer SENS CALCI or CALC2 TRAC FEED CONT lt name gt Select buffer control mode NEV or NEXT TRAC TST FORM name S
62. it for GPIB SRQ line to go true Request data from buffer Index Symbols asterisk 1 9 X more 1 9 Numerics A A V and p 1 8 Additional references 1 6 Analog 1 12 analog 2 10 ANALOG OUTPUT 1 11 AUTO 1 9 Autoranging 4 2 limits 4 2 Autozero 3 3 AZERO 1 8 Basic 2 4 2 5 3 2 connections to DUT 2 4 Buffer 1 9 6 1 Cables 1 4 Carrying case 1 6 CHASSIS 1 11 COMM 1 8 Command words 7 6 Commands 7 1 COMMON 1 11 Common 7 4 Compliance 3 12 CONFIG LOCAL key 1 8 7 3 Configuring 5 4 Connections 2 4 7 2 fundamentals 2 2 Connectors 1 4 Contact information 1 3 Current 3 2 DAMP 1 8 Default 1 16 Default settings 1 15 detected line frequency 1 14 DIGITAL 1 11 Digital 1 12 4 5 filter 4 5 filter control 4 6 DIGITS 1 8 Digits 4 3 DISP 1 8 Display 1 9 1 12 Electrochemical effects B 4 Electromagnetic Interference EMI B 5 Electrostatic interference B 4 engineering 4 3 units 1 12 ENTER 1 8 ERR 1 9 Error and status messages 7 3 Example C 1 EXIT 1 8 FAST 1 9 Features 1 6 FILT 1 9 Filters 4 4 firmware revision level 1 14 Front 7 3 Front and rear panel 1 7 Front panel 1 7 Front panel GPIB operation 7 6 Function keys 1 8 General 2 6 2 7 7 4 General IEEE 488 bus commands 7 4 General Measurement Considerations B 1 GPIB 7 2 trigger link cables and adapters 1 5 GPIB and trigger link cables and adapters 1 5 GPIB interface 7 2 GPIB status indicators 7 3 Ground link 1 11 B 2
63. l bus commands General bus commands are listed in Table 7 1 These commands are not available for the RS 232 interface Table 7 1 General bus commands Effect on Model 6487 Goes into remote when next addressed to listen Reset interface all devices go into talker and listener idle states LOCAL key locked out Cancel remote restore front panel operation for Model 6487 Returns all devices to known conditions Returns Model 6487 to known conditions Initiates a trigger Serial polls Model 6487 Common commands Common commands are summarized in Table 7 2 M odel 6487 User s Manual Remote O peration and Commands 1 5 Table 7 2 IEEE 488 2 common commands and queries Mnemonic Name Bepin CLS Clear status Clears all event registers and error queues ESE lt NRf gt Event enable command Program the standard event enable register ESE Event enable query Read the standard event enable register ESR Event status register query Read the standard event enable register and clear it IDN Identification query Returns the manufacturer model number serial number and firmware revision levels of the unit OPC Operation complete command _ Set the operation complete bit in the standard event register after all pending commands have been executed OPC Operation complete query Places an ASCII 1 into the output queue when all pending selected device operations have been completed OPT Option quer
64. le Interlock connector e Accessories as ordered e Certificate of calibration Model 6487 User Manual P N 6487 900 00 Product Information CD ROM that contains PDFs of the User s and Reference Manuals O ptions and accessories Input cables connectors and adapters 237 TRX BAR Barrel Adapter This is a barrel adapter that allows you to connect two triax cables together Both ends of the adapter are terminated with 3 lug female triax connectors Model 237 ALG 2 Triax C able This 2m 6 6 ft low noise triax cable terminated with three slot male triax connector on one end and 3 alligator clips on the other Model 237 TRX T Adapter This is a 3 slot male to dual 3 lug female triax tee adapter for use with 7078 TRX triax cables Suitable for use with the Model 6487 V Source in high voltage applications Model 237 TRX TBC Connector This is a 3 lug female triax bulkhead connector with cap for assembly of custom panels and interface connections Suitable for use with the Model 6487 V Source in high voltage applications Models 7078 T R X 3 7078 TR X 10 and 7078 TRX 20 Triax C ables These are low noise triax cables terminated at both ends with 3 slot male triax connectors The 3 model is 3 ft 0 9m in length the 10 model is 10 ft 3m in length and the 20 model is 20 ft 6m in length Model 7078 TRX TBC Connector This is a 3 lug female triax bulkhead connector with cap for assembly of custom panels and in
65. le the filter state on or off by pressing FILT The FILT annunciator will show when the filter is on SCPI commands filters Table 4 3 SCPI commands filters Commands D escription MED b Enable ON or disable OFF median filter MED RANK n Specify median filter rank to 5 AVER lt b gt Enable ON or disable OFF digital filter AVER TCON lt name gt Select filter control MOVing or REPeat AVER COUNt lt n gt Specify filter count 2 to 100 Programming example The following command sequence configures and enables both filters Median Filter MED RANK 5 Set rank to 5 MED ON Enable median filter Digital Eilter AVER COUN 20 Set filter count to 20 AVER TCON MOV Select moving filter AVER ON Enable digital filter Relative mX4b m X o reciprocal and log e Relative Explains how to null an offset or establish a baseline value Includes the SCPI commands for remote operation e mX b m X b reciprocal and Logarithmic Covers these three basic math operations and includes the SCPI commands for remote operation 5 2 Relative mX b m X b reciprocal and log M ode 6487 User s Manual Relative Relative Rel nulls an offset or subtracts a baseline reading from present and future read ings When a Rel value is established subsequent readings will be the difference between the actual input and the Rel value Displayed Rel ed Reading Actual Input Rel Value A R
66. nnect the Model 6487 to line power and turn on the instrument 1 Check to see that the line voltage indicated in the window of the fuse holder assem bly Figure 1 2 is correct for the operating voltage in your area If not refer to the procedure in Section 17 of the Model 6487 Reference Manual for setting line volt age and fuse replacement CAUTION Operating the instrument on an incorrect line voltage may cause dam age to the instrument possibly voiding the warranty 2 Before plugging in the power cord make sure that the front panel power switch is in the off O position 3 Connect the female end of the supplied power cord to the AC receptacle on the rear panel Connect the other end of the power cord to a grounded AC outlet WARNING Thepower cord supplied with the Model 6487 contains a separate ground terminal for use with grounded outlets W hen proper connec tions are made instrument chassis is connected to power line ground through the ground wire in the power cord Failure to use a grounded outlet may result in personal injury or death due to electric shock 4 Turn on the instrument by pressing the front panel power switch to the on I position Line frequency The Model 6487 operates at line frequencies of 50 or 60Hz When auto detect is enabled factory default line frequencies are automatically sensed and set accordingly therefore there are no switches to set Use the SYST LFR command query to read the line fre
67. notice Rev A HW 10 25 02 General M easurement Considerations B 2 General M easurement Considerations Model 6487 User s Manual Measurement considerations The following measurement considerations apply to all precision measurements Table 2 1 lists all measurement considerations and indicates where to find detailed information on them For additional measurement considerations see Appendix G of the Model 6487 Reference Manual For comprehensive information on all measurement considerations refer to the Low Level Measurements handbook which is available from Keithley Ground loops Ground loops that occur in multiple instrument test setups can create error signals that cause erratic or erroneous measurements The configuration shown in Figure B 1 intro duces errors in two ways Large ground currents flowing 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 currents are small magnetic flux cutting across the large loops formed by the ground leads can induce sufficient voltages to disturb sensitive measurements Figure B 1 Power line ground loops Signal Leads Instrument 1 Instrument 2 Instrument 3 Veo ee 7 Ground 4 Loop i X Current Power Line Ground To prevent ground loops instruments should be connected to ground at only a single point as sho
68. o configure trigger properties U se to perform and create limit tests U se to set display resolution U se to select measurement rate Use to control cursor position for making selections or editing values U se to save present setup to a memory location Use to restore setup to either GPIB or factory defaults or to a user memory location Also use to modify properties of power on defaults to either GPIB or factory defaults or to a user memory location U se to start buffer and modify the number of readings to store U se to display stored readings including maximum minimum peak to peak aver age and standard deviation The A and W range keys scroll through the buffer and the lt or b key toggles between reading number reading and timestamp Use to control auto zero function on off Use to control damping function on off U se to cancel selection and move back to measurement display U se to accept selection and move to next choice or back to measurement display M odel 6487 User s Manual Getting Started 1 9 4 Rangekeys A Use to select the next higher measurement range Also use to modify the upper auto range limit v Use to select the next lower measurement range Also use to modify the lower auto range limit AUTO Enables disables autorange 5 Handle Pull out and rotate to desired position 6 VOLTAGE SOURCE OPERATE indicator This indicator will turn on when the voltage source is in operate voltage so
69. occur the OCOMP annunciator Output Compliance will flash and the displayed voltage value visible when current readings are configured for readings of less than 6 2 digits will alternate between showing the value and displaying CMPL If you are in a menu where the voltage source value is not shown on the right most four characters of the display only the flashing OCOMP annunciator will be shown Model 6487 User s Manual O pen interlock indication M easurements and Sourcing Voltage 3 13 If the interlock is asserted opened while the unit is on the 50V or 500V range the voltage source will also technically be in compliance However there will be no indication of that status over the front panel or in the status registers The open interlock takes precedence SCPI commands voltage source Table 3 7 SCPI commands voltage source SOUR VOLT Voltage Set the source output level 500 to 500V SOUR VOLT RANG Range _ Set source range to one of three ranges 10 50 and 500V SOUR VOLT ILIM lt Limit gt Set the source current limit 2 5e 5 2 5e 4 2 5e 3 or 2 5e 2 1 SOUR VOLT STAT lt b gt Enable ON or disable OFF source output SOUR VOLT INT lt b gt Enable ON or disable OFF interlock for 10V range SOUR VOLT INT FAIL Query interlock state 1 asserted source output cannot be turned on 1 2 5e 2 not available for 50V and 500V ranges 2 See Section 2 for interlock operation Pro
70. off The OPER key will toggle the voltage source state on off The Model 6487 will output the configured voltage and the VOLTAGE SOURCE OPERATE indicator will turn on O PER operate key The OPER operate key will function to turn the voltage source off even if the instrument is operating under remote control REM annunciator on assuming that the LLO Local Lockout function has not been employed While in remote the OPER key will only turn the source off To turn it on the Model 6487 must be in local see Section 7 Voltage source off state The voltage source is not in a high impedance state when it is turned off Rather it is in a state that acts just like the voltage source was programmed to OV on the selected range It will enter this state on power up after the VOLTAGE SOURCE OPERATE light blinks In contrast the safety interlock will cause the voltage source to go into a high impedance state instead of OV output and the source will stay in the high impedance state until the operate state is changed to on The exception is the 10V range where the interlock is optional The OPERATE light and front panel display do not indicate the difference between OV output and high impedance output caused by an open interlock The interlock status is available by query via remote see Table 3 7 Compliance indication At any time it is possible that the voltage source will go into compliance current limit reached Should this situation
71. ontact with hazardous live circuits Maintenance personnel perform routine procedures on the product to keep it operating properly 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 personnel 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 Keithley products are designed for use with electrical signals that are rated Installation Category I and Installation Category II as described in the International Electrotechnical Commission IEC Standard IEC 60664 Most measurement control and data I O signals are Installation Category I and must not be directly connected to mains voltage or to voltage sources with high tran sient over voltages Installation Category II connections require protection for high transient over voltages often associated with local AC mains connections Assume all measurement control and data I O connections are for connection to Category I sourc es unless otherwise marked or described in the Manual Exercise extreme caution when a shock hazard is present Lethal voltage may be present on cable connector jacks or test fixtures The American National Standards Institute ANSI states that a
72. orrection wi sesssevasesnvsedniuncdeaswoenercassoednaranstoents 3 3 AUGZIO NETT 3 3 Zero check and zero correct n 3 3 Current The aste Te DES spirato aiar 3 5 LLC RI RR CORTE TA 3 5 SCPI programming current measurements 3 7 Programming example current measurements 3 7 Ohms measurements urina alessio ni 3 8 B f E 3 8 PO LEE 3 8 SCPI programming ohms measurements 3 10 Programming example ohms measurements 3 11 Voltage source operation 3 11 Configuring the voltage source 3 11 Sourcing voltage C 3 12 Compliance indication csi sanessioetebavetonadesmsraoens 3 12 Open interlock indication seen 3 13 SCPI commands voltage source 3 13 Programming example voltage e 3 13 Range U nits D igits Rate and Filters Range units and digits lione 4 2 ESELON EA N PE Re T EAT 4 2 NING RR aa NEE E E OE 4 3 biblia 4 3 SCPI programming range and digits 4 3 0 M M O 4 4 E 100 9 5 APPROPRIATA IN 4 4 PU METRE 4 4 Median AIET RR ERROR 4 5 DO alias 4 5 Filter contiol INVERTER 4 6 Relative mX b m X b reciprocal and log RENE 5 2 Front p
73. ource output The VOLTAGE SOURCE OPERATE indicator will turn on Step 7 Disable zero check and take a reading from the display If the readings are noisy use filtering to reduce noise It may be advisable to use the alternating voltage ohms or add shielding NOTE For any ohms measurements the ohms reading is invalid and unknown if the voltage source is in compliance Therefore a value of 9 9e 36 will be returned over the GPIB and the message I LIMIT will be displayed on the front panel for both normal readings and buffer recall readings for any ohms readings where the voltage source went into compliance 3 10 M easurements and Sourcing Voltage M odel 6487 User s Manual Figure 3 2 Connections for ohms measurements Red HI le M etal Noise Shield Metal Safety Shield Chassis T Safety 237 ALG 2 Earth Ground Cable Black LO DUT Device Under Test V SO U RCE OUTPUT INPUT 630mAT 100 VAC M odel 6487 SCPI programming ohms measurements Table 3 5 SCPI commands basic ohms measurements SENS OHMS ON Select ohms function RANG lt Range gt Select manual current range 0 021 to 0 021A RANG AUTO lt b gt Enable ON or disable OFF auto current range SOUR VOLT RANG lt Range gt Set voltage source range 10 50 or 500 SOUR VOLT lt Volts gt Set output voltage 505V to 505V SOU
74. p CENTer and SPAN are alternate methods of setting sweep parameters They are coupled with STARt and STOP commands 6 6 Buffer and Sweeps Programming example Model 6487 User s Manual The following command sequence performs a sweep from 1V to 10V in 1V increments RST SOUR VOLT SWE STAR 1 SOURSVOLISSSWESSTIOPR 10 SOUR VOBITSWESSIEP 1 SOUR VOLT SWE DEL 0 1 ARM COUN INF FORM ELEM READ VSO SOUR VOLT SWE INIT SYST ZCH OFF INIT TRAC DATA Return 6487 to RST defaults Start voltage IV Stop voltage 10V Step voltage 1V 0 1s delay Reset arm count Select reading voltage source data Arm sweep put source in operate Turn off zero check Trigger sweep Request all stored readings Remote O peration and Commands Selecting and configuring an interface Explains how to select and configure an interface GPIB or RS 232 R emote commands Lists the following types of bus commands general bus commands common commands signal oriented commands and SCPI subsystems 1 2 Remote O peration and Commands M odel 6487 User s Manual Selecting and configuring an interface Interfaces The Model 6487 supports two built in remote interfaces GPIB interface and RS 232 interface You can use only one interface at a time At the factory the GPIB is selected To select the interface press COMM select RS 232 or GPIB then press ENTER The Model 6487 will reset with the new interface selected GPIB
75. pplicability 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 instrument 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 accord ing to instructions If the board becomes contaminated and operation is affected the board should be returned to the factory for proper cleaning servicing Table of Contents 1 Getting Started V E 106 00 510 0 MERERI 1 2 Overview of this manual eene 1 2 General morma OI ascii 1 2 Warranty information 1 2 Contact Information urina 1 3 Safety symbols and terms 1 3 Unpacking and Inspection iei ott eene 1 3 Options and accessories 1 4 ICT ossiosdeusu tun abdo EAR EI 1 6 Additional references 1 6 ola 1 6 Front and rear panel familiarization esses 1 7 Front panel SUFT OEV sori 1 7 Rear panel summary eese nennen 1 10 hou ee M TN 1 12 Analog output nennen nnne eene enne 1 12 DO 1 12 Dipinti 1 12 Status and error MESSAGES siria 1 12 gu iij licia 1 13 Lime power COMME CHON sisi 1 13
76. put cables connectors and adapters page 1 4 in Section 1 for recommended cables and test leads 2 4 Connections Model 6487 User s M anual Basic connections to DUT Current measurement connections Basic connections for current measurements are shown in Figure 2 3 the DUT is the cur rent to be measured Circuit high is connected to the center conductor of the input connec tor and circuit low is connected to the connector s input LO inner shield Figure 2 3 Basic current measurement connections INPUT Maximum Continuous Input 505V Peak WARNING If itis possible for the DUT or external supply to present more than 505V to the input HI it is imperative that the connection between input LO and the external voltage source be sufficiently low impedance and capable of carrying the short circuit current of the source in order that the LO not exceed 505V CAUTION Current limiting resistors are required for DU Ts capable of forcing voltages 505V or greater Damage to the instrument may result if volt ages greater than 505V are forced on the Model 6487 INPUT HI Ohms measurement connections Basic connections for ohms measurements are shown in Figure 2 4 the DUT is the resis tance to be measured Circuit high is connected to the center conductor of the INPUT con nector and circuit low is connected to the V SOURCE OUTPUT HI terminal Note that INPUT LO and V SOURCE OUTPUT LO are connected together externally Model 6487 Use
77. r module 1 11 Power up 1 13 Power up sequence 1 14 Programming C 2 Query commands 1 19 Rack mount kits 1 6 Range 4 2 keys 1 9 Units Digits Rate and Filters 4 1 Rate 1 8 4 4 Rear panel 1 10 Rear panel summary 1 10 RECALL 1 8 Recall 6 2 REL 1 8 1 9 Relative 5 1 Relative mX b m X b Reciprocal and Log 5 1 REM 1 9 Remote 7 1 REN remote enable 7 6 resistivity 2 6 Response time 4 6 Restoring 1 15 RS 232 1 11 connections 7 2 RS 232 7 2 RS 232 interface 7 2 safety shield 3 6 3 9 Safety symbols and terms 1 3 SAVE 1 8 Saving 1 15 scientific SCI 4 3 scientific notation 1 12 SCPI 3 10 3 13 4 6 6 5 7 6 SCPI commands amps function 3 7 3 10 buffer 6 4 SCPI programming mX b m X b and log 5 4 range and digits 4 3 relative 5 2 zero check and zero correct 3 4 select power on setup 1 15 serial number 1 18 Setting and controlling relative 5 2 SETUP 1 8 Shielding 2 6 Signal 7 5 SLOW 1 9 Sourcing 3 1 3 12 Special keys and power switch 1 8 Specifications A 1 SRQ 1 9 STAT 1 9 statistics 6 3 Status 1 12 STD DEV 6 3 STORE 1 8 Store 6 2 Sweeps 6 1 sweeps 6 5 TALK 1 9 Test fixture 2 6 TIMER 1 9 timestamps 6 2 Triax 2 2 Triboelectric effects B 3 TRIG 1 8 1 9 TRIGGER LINK 1 11 Units 4 3 Unpacking and Inspection 1 3 user setup 1 15 V 1 11 Voltage 1 12 2 2 3 2 3 3 3 12 Warm up period 3 3 Warranty 1 2 Warranty information 1 2 ZCHK 1 8 Zero 3 3 KEIT
78. r s Manual Connections 2 5 Figure 2 4 Basic ohms connections Maximum Continuous Input 505V Peak Noise and safety shields Figure 2 5 shows typical measurement shielding In A a noise shield is used to prevent unwanted signals from being induced on the picoammeter input Amps measurements below 1uA may benefit from effective shielding Typically the noise shield is connected to picoammeter input LO Additionally Figure 2 5 B shows an added safety shield con nected to earth ground and Model 6487 chassis This type of shielding should be used whenever hazardous voltages will be present in the test circuit WARNING Themaximum safe voltage between picoammeter LO and chassis ground common mode voltage is 505V peak T he M odel 6487 does not internally limit the LO to chassis voltage E xceeding 505V can cre ate a shock hazard If itis possible for the DUT or external supply to present more than 505V to the input HI it is imperative that the connection between input LO and the external voltage source be sufficiently low impedance and capable of carrying the short circuit current of the source in order that the LO not exceed 505V CAUTION TheLO to chassis breakdown voltage is 505V E xceeding this voltage may cause damage to the instrument 2 6 Connections Model 6487 User s Manual Figure 2 5 Shielding for measurements unguarded
79. rogram message as long as they are separated by semicolons Model 6487 User s Manual Remote O peration and Commands 7 7 The query command requests the presently programmed status It is identified by the ques tion mark at the end of the fundamental form of the command Most commands have a query form Each program message must be terminated with an LF line feed EOI end or identify or an LF EOI Each response is terminated with an LF line feed and EOI end or identify Parameter types The following are some of the common parameter types lt b gt lt name gt lt NRf gt lt NDN gt lt n gt Boolean Used to enable or disable an instrument operation 0 or OFF disables the operation and 1 or ON enables the operation Name parameter Select a parameter name from a listed group Numeric representation format A number that can be expressed as an integer e g 8 a real number e g 23 6 or an exponent 2 3E6 Non decimal numeric A non decimal value that can be used to program status enable registers A unique header identifies the format B binary H hexadecimal and Q octal Numeric value Can consist of an NRf number or one of the fol lowing name parameters DEFault MINimum or MAXimum When the DEFault parameter is used the instrument is programmed to the RST default value When the MINimum parameter is used the instrument is programmed to the lowest allowable v
80. ruments Model 6487 User s Manual Table 2 1 Connections 2 11 Summary of measurement considerations Input bias current Voltage burden Noise Ground loops Triboelectric effects Piezoelectric and stored charge effects Electrochemical effects Humidity Light Electrostatic interference Magnetic fields Electromagnetic interference EMI See Model 6487 Reference Manual Appendix G for details Offset current of Model 6487 could affect low current measurements Offset voltage of Model 6487 could cause errors if it is high in relation to the voltage of the measured circuit Noise generated by source resistance and source capacitance See Appendix B for details Multiple ground points can create error signals Charge currents generated in a cable by friction between a conductor and the surrounding insulator i e bending a triax cable Currents generated by mechanical stress on certain insulating materials Currents generated by the formation of chemical batteries on a circuit board caused by ionic contamination Reduces insulation resistance on PC boards and test connection insulators Light sensitive components must be tested in a light free environment Charge induced by bringing a charged object near your test circuit The presence of magnetic fields can generate EMF voltage EMI from external sources 1 e radio and TV transmitters can affect sensitive measurements 2 12 Connections
81. ry reset are as shown Model 6487 User s Manual Table 1 1 continued D efault settings RS 232 No effect Off at factory Getting Started Factory GPIB SYStem PRESet RST All Settings No effect Trigger Layer CONFIG TRIG Trig In Source Event Trigger Count Trigger Delay Input Trigger Link Line Source Bypass Output Trigger Link Line Voltage Source Operate Amplitude Range Current Limit 10V Range Interlock Sweeps Start Voltage Stop Voltage Step Voltage Center Voltage Span Voltage Delay Is Zero Check Enabled Zero Comet Disabled The factory SYStem PRESet and bus RST GPIB defaults are the same Bus settings that are different from factory reset are as shown x X X X x X X 1 17 1 18 Getting Started Model 6487 User s Manual Menu Table 1 2 Many aspects of operation are configured through the menus summarized in Table 1 2 Refer to the section listed in the table for in depth information To access the menu press the MENU key Use the A and W range keys to scroll through the menu items and the lt q and p cursor keys to change options Press ENTER to save any changes made and then leave the menu Press EXIT to leave the menu without saving changes NOTE The MENU key is used to access the menu structure However if in remote for IEEE 488 bus operation REM annunciator is lit pressing the menu key has no effect Press the LOCAL
82. s are located in Section 14 of the Model 6487 Reference Manual Table 7 4 SCPI command subsystems CALCulate 1 CALCulate2 CALCulate3 CALibration DISPlay FORMat SENSe 1 SOURce 1 SOURce2 STATus SYSTem TRACe TRIGger Math functions Limit tests relative Buffer statistics Instrument calibration Display digits and text messages Format of returned remote data Current measurements and associated modes Voltage source operation Digital I O port Instrument status Zero check correct line frequency error messages Buffer operation and data Instrument triggering Programming syntax The following paragraphs cover syntax for both common commands and SCPI commands For more information see the IEEE 488 2 and SCPI standards Command words Program messages are made up of one or more command words Common commands and SCPI commands may or may not use a parameter There must be at least one space between the command word and its parameter Some command words are enclosed in brackets These brackets are used to denote an optional command word that does not need to be included in the program message Common commands and SCPI commands are not case sensitive You can use upper or lower case and any case combination A SCPI command word can be sent in its long form or short form version The command tables in this manual use the short form version You can send multiple command messages in the same p
83. sable zero check and take a reading from the display If the readings are noisy you may want to use filtering to reduce noise Filtering is covered in Section 4 Figure 3 1 Connections for current measurements Red HI pa M etal Noise Shield Metal Safety Shield Chassis Safety Cable Ground t 00000 LIN INPUT HI INTERLOCK 630mAT 100 VAG SB 120 VAC Model 6487 User s Manu al M easurements and Sourcing Voltage 3 7 SCPI programming current measurements Table 3 4 SCPI commands basic current measurements Select current function Select manual range 0 021 to 0 0214 Enable ON or disable OFF auto FUNC CURR RANG Range RANG AUTO b INIT READ range Trigger reading Trigger and return reading s Zero correct and zero check commands not included See Table 3 3 Programming example current measurements The following command sequence will perform one zero corrected current measurement RST FUNC SYST RANG INIT SoL SYST RANG SYST READ CURR ZCH ON 2e 9 ACOR ACO ZCOR ON AUTO ON LCH OFF Return 6487 to GPIB defaults Select current function Enable zero check Select the 2nA range Trigger reading to be used as zero correction Use last reading taken as zero correct value Perform zero correction Enable auto r
84. shock hazard exists when voltage levels greater than 30V 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 Operators of this product must be protected from electric shock at all times The responsible body must ensure that operators are prevented access and or insulated from every connection point In some cases connections must be exposed to potential human contact Product operators in these circumstances must 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 Do not connect switching cards directly to unlimited power circuits They are intended to be used with impedance limited sourc es NEVER connect switching cards directly to AC mains When connecting sources to switching cards install protective de vices to limit fault current and voltage to the card Before operating an instrument make sure the line cord is connected to a properly grounded power receptacle Inspect the con necting cables test leads and jumpers for possible wear cracks or breaks before each use When installing equipment where access to the main power cord is restricted such as rack mounting a separate main input pow er disconnect device must be provided in close proximity to the equipment and within easy reach of the operator For maximum s
85. t To enable or disable damping from the front panel simply press the DAMP key Note that the FILT annunciator will be on when damping is enabled Via remote send DAMP ON or DAMP OFF Note that the FILT annunciator is used for both the analog damping filter and the two types of digital filters Filtering stabilizes noisy measurements caused by noisy input signals The Model 6487 uses two types of filters median and digital The displayed stored or transmitted reading is simply the result of the filtering processes Note that both the median and digital filters can be in effect at the same time With both filters enabled the median filter operation is performed first After the median filter yields a reading it is sent to the stack of the digital filter Therefore a filtered reading will not be displayed until both filter operations are completed The settings for the filter are global and both are controlled with the FILT key When either the median or digital filter is enabled the FILT annunciator is on Note that the FILT annunciator is used for both the digital filters and the analog damping filter M odel 6487 User s Manual Range Units Digits Rate and Filters 4 5 Median filter The median filter is used to determine the middle most reading from a group of readings that are arranged according to size For example assume the following readings 20mA ImA 3mA The readings are rearranged in an ascending order as follows
86. t the prompts enter the start stop and step voltages and the delay time time between each voltage step and measurement Note that sweeps can be positive going or negative going by programming the start and stop voltages accordingly but the programmed step voltage is always positive The SCAN annunciator will turn on to indi cate that the sweep is armed To start a sweep press the TRIG key The sweep will be performed and readings will be stored in the buffer for later recall see Recall page 6 2 To abort a sweep in progress press the EXIT key SCPI programming sweeps NOTE When programming sweeps via remote the arm count may have to be reset to initiate after RST See Section 7 of the Model 6487 Reference Manual for details on triggering Table 6 2 SCPI commands sweeps Commands D escription SOUR VOLT SWE STAR Volts Program start voltage 505V to 505 V SOUR VOLT SWE STOP Volts Program stop voltage 505V to 505 V SOUR VOLT SWE STEP Volts Program step voltage 505V to 505V SOUR VOLT SWE CENT Volts Program center voltage 505V to 505 V SOUR VOLT SWE SPAN Volts Program span voltage OV to 1010V SOUR VOLT SWE DEL Delay Set delay between voltage step and measurement 0 to 999 9999s SOUR VOLT SWE INIT Arm sweep put source in operate SOUR VOLT SWE ABOR Abort sweep put source in standby SOUR VOLT SWE STAT Query if sweep still running 2 sweep in progress INIT Trigger swee
87. terface connections Suitable for use with the Model 6487 V Source in high voltage applications Model 8009 R esistivity Test Fixture This is a guarded test fixture for measuring vol ume and surface resistivities It can accommodate sheet samples with a diameter between 64 and 102mm 2 to 4 in and a thickness of up to 3 175mm V6 in M odel 6487 User s Manual Getting Started 1 5 M odel 8606 High Performance Probe Tip K it Consists of two spade lugs two alliga tor clips and two spring hook test probes The spade lugs and alligator clips are rated at 30V RMS 42 4V peak the test probes are rated at 1000V These components are designed to be used with high performance test leads terminated with banana plugs such as the Model 8607 High Performance Banana Cables M odel 8607 High Performance Banana C ables Consists of two high voltage 1000V banana cables The cables are terminated with banana plugs that have retractable sheaths CAP 31 Protective Shield C ap For use with 3 lug triax connectors Interlock cables and connector Model 6517 ILC 3 Interlock C able Designed to connect the interlock of the Model 6487 to the Model 8009 test fixture Model 8002 IL C 3 Interlock C able Designed to connect the lid interlock circuit of a test fixture to the interlock circuit of the Model 6487 C S 459 4 pin Female Interlock C onnector Allows custom wiring of external circuits to the Model 6487 interlock GPI
88. this output depending on range The output impedance is 100 To minimize the effects of loading the input impedance of the device connected to the ANALOG OUT should be as high as possible 2 10 Connections Model 6487 User s Manual Figure 2 9 Typical analog output connections WARNING WEATOR SERVICABLE PARTS SERVICE BY QUALIFIED PERSONNEL ONLY ei KEITHLEY A sl MADE IN C AR ecccc USA 30 30 ecco cATI qu nese CE ANALOG OUT DIGITAL I O WITH FRONT PANEL MENU L O 7 e 2j N 2 505v PK cecco 5 A y 505V PK ccoo 505V PK INPUT TRIGGER LINK RS 232 V SOURCE OUTPUT 505V PK TO CHASSIS e 3m A LO LA HlinteRLock Aa fr Rc A FUSE LINE 5 H 630mAT 100 VAC 505V SB 120 VAC E MAX SISmAT 220 VAC SB 240VAC j 1 e CAUTION FOR CONTINUED PROTECTION AGAINST FIRE HAZA iD REPLACE FUSE WITH SAME TYPE AND RATING co Test Lead Model 6487 Rear Panel M easuring Device i e Chart recorder Measurement considerations There are a variety of factors to consider when making low level measurements These con siderations are summarized in Table 2 1 and are detailed in Appendix G of the Model 6487 Reference Manual and Appendix B of this manual For comprehensive information on all measurement considerations refer to the Low Level Measurements handbook which is available from Keithley Inst
89. ting or disconnecting input signals Zero correct NOTE The Model 6487 saves a single zero correct value not one for each range For best results acquire a new zero correct value after changing to the desired range 3 4 M easurements and Sourcing Voltage M odel 6487 User s Manual The Model 6487 has a zero correct feature to algebraically subtract the voltage offset term from the measurement Perform the following steps to algebraically zero correct the measurement Enable zero check by pressing ZCHK ZEROCHK message displayed Select the range that will be used for the measurement or select the lowest range Press REL to enable zero correct MON annunciator turns on Press ZCHK to disable zero check Readings can now be taken from the display The MON annunciator indicates that the displayed reading is zero corrected joe pe uc pus opes 6 To turn off zero correct press REL again with zero check enabled NOTES With regard to the zero correct feature e The Model 6487 will remain zero corrected even if it is upranged If down ranged re zero the instrument e The Model 6487 does not have to be re zero corrected as long as the ambient temperature remains stable e Zero correction cancels the voltage offset term of the amplifier With zero correct enabled the instrument may not display a perfectly zeroed reading e Ifthe Model 6487 is operating at or near Tax zero correction will have very little effect Tcr is t
90. tions Appendix C Example Programs General information Warranty information Warranty information is located at the front of this manual Should your Model 6487 require warranty service contact the Keithley representative 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 to provide the repair facility with the necessary information M odel 6487 User s Manual Getting Started 1 3 Contact information Worldwide phone numbers are listed at the front of this manual If you have any questions please contact your local Keithley representative or call one of our Application Engineers at 1 800 348 3735 U S and Canada only Safety symbols and terms The following symbols and terms may be found on the instrument or used in this manual If or d is present connect it to safety earth ground using the wire recommended in the user documentation The A symbol on an instrument indicates that the user should refer to the operating instructions located in the manual The N symbol on an instrument shows that it can source or measure 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 The WARNING heading used in this manual explains dangers that might result in per sonal injury or death Always
91. tistics and reading values use the cursor keys to select among readings voltage source values and timestamps The BUFFER annunciator will be on while readings are being recalled Press EXIT to return to normal display NOTE Ifthe voltage source was in compliance when the reading was acquired the recalled front panel SRC display will show the voltage value dimmed Over the GPIB a value of 999 returned for the voltage source element indicates that the source was in compliance Buffer timestamp To change the buffer timestamp format press MENU select TSTAMP then press ENTER Select the desired option ABS absolute or DELT delta For ABS each times tamp is referenced to the first reading stored in the buffer The first reading always has a timestamp of 0000000 0000 With DELT each timestamp provides the time between the readings M odel 6487 User s Manual Buffer and Sweeps 6 3 Clear To clear the buffer press CONFIG followed by STORE then set the reading count to 0 pressing AUTO will clear the display quickly Press ENTER with a reading count of 0 displayed to finish clearing the buffer Buffer statistics MIN and MAX provides the minimum and maximum readings stored in the buffer It also indicates the buffer location of these readings The PK PK peak to peak value is the difference between the maximum and minimum readings stored in the buffer PK PK MAX MIN e Average is the mean of the buffer readings Mean
92. tory page Revision A Document Number 6487 900 01 seen October 2002 All Keithley product names are trademarks or registered trademarks of Keithley Instruments Inc Other brand names are trademarks or registered trademarks of their respective holders Safety Precautions The following safety precautions should be observed before using this product and any associated instrumentation Although some instruments and accessories would normally be used with non hazardous voltages there are situations where hazardous conditions may be present This product is intended for use by qualified personnel who recognize shock hazards and are familiar with the safety precautions required to avoid possible injury Read and follow all installation operation and maintenance information carefully before us ing the product Refer to the manual for complete product specifications If the product is used in a manner not specified the protection provided by the product may be impaired 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 equip ment 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 must be trained in electrical safety procedures and proper use of the instrument They must be protected from electric shock and c
93. trigger count to 8 Set integration rate to 01 PIC Use 2mA range Turn zero check off Turn auto zero off Lum display off Operation complete query synchronize completion of commands In 488 1 mode this will automatically do a READ see Reference manual Turn display back on C 4 Example Programs 3000 readings into internal buffer Model 6487 User s Manual NOTE Due to memory limitations the maximum product of the trigger count times the arm count is 2 046 Consequently two triggers are required to completely fill the buffer to its 3 000 reading maximum See Section 7 of the Model 6487 Reference Manual for triggering details VES TRIG TRIG NPLC RANG SYST DEL 0 COUN 1500 01 201077 ZACH OFF CES TRAC POIN 3000 TRAC CLE TRAC FEED CONT NEXT STAT MEAS ENAB 512 SRE iL MOP GE read back result of opc INIT INIT TRAC DATA read back result Return 6487 to RST defaults Set trigger delay to zero seconds oer trigger count to 1500 Set integration rate to 01 PLC Use 2mA range Turn zero check off Clear status model Set buffer size to 3000 Clear buffer Set storage control to start on next reading Enable buffer full measurement event Enable SRO on buffer full measurement event Operation complete query synchronize completion of commands First trigger to store 1500 readings wait for reading storage complete Take and store last 1500 readings wa
94. troublesome signal External filtering of the input signal path may be required In some cases a simple one pole filter may be sufficient In more difficult situations multiple notch or band stop fil ters tuned to the offending frequency range may be required Connecting multiple capac itors of widely different values in parallel will maintain a low impedance across a wide frequency range Keep in mind however that such filtering may have detrimental effects such as increased response time on the measurement C Example Programs C 2 Example Programs Programming examples Model 6487 User s Manual This section contains example programs pseudo code to achieve speed and buffer size specifications 1000 readings second into internal buffer NOTE This program configures the Model 6487 to 0 01 PLC digital filters off front panel off auto zero off as well as takes and stores 2000 readings RST TRIG TRIG NPLC RANG 002 oaxoltAUCH ORE DL C AZRERSTSTAL OFE DEL 0 COUN 2000 01 DISP SC ISS SE NAB ORE POIN 2000 CLE FEED CONT NEXT TRAC TRAC TRAC STAT MEAS ENAB 512 NOIRE dl OPCE read back result of opc INIT DISP ENAB ON TRAC DATA read back result Return 6487 to RST defaults Set trigger delay to zero seconds Set trigger count to 2000 Set integration rate to 01 PLC Use 2mA range Turn zero check off Turn auto zero off Turm display Off Clear status model
95. urce output turned on It Will also turn on for about 0 7 sec at power on to indicate that it is functional WARNING Hazardous voltage may be present on the rear panel V SOURCE OUTPUT terminals when the operate indicator is on 7 Display annunciators Readings being stored in buffer Indicates additional selections are available asterisk Mf more AUTO Autorange enabled BU FFER Recalling readings stored in buffer ERR Q uestionable reading or invalid cal step FAST Fast 0 1 PLC reading rate selected FILT M EDIAN and or AVERAGE filter enabled also DAM PING enabled LSTN Instrument addressed to listen over GPIB M ATH mX b m X b or log10 calculation enabled M ED M edium 1 PLC reading rate selected REL Relative enabled for present measurement function REM Instrument in GPIB remote mode SLOW Slow reading rate selected 6 PLC for 60Hz or 5 PLC for 50Hz SRQ Service request over GPIB STAT Displaying buffer statistics TALK Instrument addressed to talk over GPIB bus TIM ER Timer controlled triggering in use TRIG External triggering GPIB or trigger link selected MON Zero correct enabled SCAN Voltage sweep armed and ready to run OCOMP Voltage source in compliance 1 10 Getting Started Model 6487 User s Manual Rear panel summary The rear panel of Model 6487 is shown in Figure 1 2 Figure 1 2 Rear panel IEEE 488 CHANGE IEEE ADRESS WITH FRONT PANAL MENU TRIGGER LINK RS 2
96. voltage setting fuse replacement power line frequency and the power up sequence D efault settings Covers the five instrument setup configurations available to the user three user defined GPIB defaults or factory defaults SCPI programming Explains how SCPI commands are presented in this manual 1 2 Getting Started M odel 6487 User s M anual Introduction The Model 6487 is a high resolution bus programmable RS 232 and IEEE 488 picoam meter The Model 6487 has the following current measurement ranges 8 ranges from 20mA down to the 2nA range The Model 6487 also includes a 500V DC voltage source and an ohms function that includes an alternating voltage mode to improve accuracy and repeatability of very high resistance measurements O verview of this manual This manual describes how to connect program and maintain the Model 6487 Picoamme ter The sections of the manual are organized as follows Section 1 Getting Started Section 2 Connections Section 3 Measurements and Sourcing Voltage Section 4 Range Units Digits Rate and Filters Section 5 Relative mX b m X b reciprocal and log Section 6 Buffer and Sweeps Section 7 Remote Operation and Commands Appendices to this manual contain specification and also provide additional information on specific topics The appendices are organized as follows Appendix A Specifications Appendix B General Measurement Considera
97. wn in Figure B 2 Note that only a single instrument 1s connected directly to power line ground Experimentation is the best way to determine an acceptable arrangement For this purpose measuring instruments should be placed on their lowest ranges The configu ration that results in the lowest noise signal is the one that should be used A convenient way to make this connection uses the ground link at the rear of the Model 6487 Model 6487 User s Manual General M easurement Considerations B 3 Figure B 2 Eliminating ground loops Instrument 1 Instrument 2 Instrument 3 Power Line Ground Triboelectric effects Triboelectric currents are generated by charges created between a conductor and an insula tor due to friction Here free electrons rub off the conductor and create a charge imbalance that causes the current flow For example bending a triaxial cable causes friction between the center conductor HI and its surrounding insulator resulting in triboelectric currents Triboelectric currents can be minimized as follows Use low noise cables These cables are specially designed to minimize charge generation and use graphite to reduce friction The Keithley Model 237 and 7078 cables are low noise e Use the shortest cables possible and secure them 1 e taping or tying to a non vibrating surface to keep them from moving Piezoelectric and stored charge effects Piezoelectric currents are generated when mechanical stress is applied
98. y Returns model number of any installed options RCL lt NRf gt Recall command Returns Model 6487 to the user saved setup RST Reset command Returns Model 6487 to the RST default conditions SAV lt NRf gt Save command Saves the present setup as the user saved setup SRE lt NRf gt Service request enable command Programs the service request enable register SRE Service request enable query Reads the service request enable register STB Status byte query Reads the status byte register TRG Trigger command Sends a bus trigger to Model 6487 TST Self test query Performs a checksum test on ROM and returns the result WAI Wait to continue command Wait until all previous commands are executed Signal oriented commands Signal oriented commands used to make basic measurements are shown in Table 7 3 Table 7 3 Signal oriented commands Command D escription CONFigure lt function gt Places Model 6487 in a one shot measurement mode lt function gt CURR DC CONFigure Queries the selected function Returns CURR FETCh Requests the latest reading s READ Performs an INITiate and a FETCh MEASure function Performs a CONFigure function and a READ Remote O peration and Commands Model 6487 User s Manual SCPI command subsystems Table 7 4 summarizes the various SCPI subsystems used to program most Model 6487 operations Detailed lists of commands associated with these subsystem

Model 6487 Picoammeter/Voltage Source User's Manual

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