KEI 486, 487 Quick Ref 电路图.pdf

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1、Model 486 PICOAMMETER Model 487 PlCOAMMETER/SOURCE QUICK REFERENCE GUIDE RadioFans.CN 收音机爱 好者资料库 INTRODUCTION This quick reference guide contains descriptions of vari- ous features and information concerning the operation of the Model 4861487. 21990, Keithley Instruments, Inc. All rights reserved. C

2、leveland, Ohio, U.S.A. Document Number: 486-903-01 Rev. A 1 RadioFans.CN 收音机爱 好者资料库 Asyst ts a registered trademark of Asyst Software technologies. Hewtett-Packard Is a registered trademark of Hewlett-Packard Company. IBM and AT are registered trademarks and PC/XT is a trademark of International Bus

3、iness Machines, IC. PC instrument trig- gered while still processing a pre- vious trigger. CAL VALUE Calibration value conflicts with the currently selected range. CAL ERROR Calibration value not within allow- able limits. CAL LOCK Sent calibration command with calibration switch (CAL LOCK) disabled

4、. CAL ZCHK Cannot calibrate picoammeter with zero check enabled. INTERLOCK Tried to put V-Source of Model 487 in operate while an enabled safety interlock switch is open. CURRENT MEASUREMENTS Current Ranges SHIFT ? v RANGE A El 0 AUTO RANGE The available current ranges of the Model 4861487 are liste

5、d in Table 2. 2nA 20nA 200nA 2c1A 20/.iA 2oopA 2mA 2.19999inA Higher voltages require current to be limited to 3mA. 2.19999nA 21.9999nA 219.999nA 2.19999pA 21.9999pA 219.999uA 35OVdc 35OVdc 35OVdc 35OVdc 5OVdc 50Vdc 50Vdc Table 2. Current Ranges . Autorange is enabled by pressing SHIFTand then AUTO

6、RANGE in that order. CAUTION To avoid possible damage to the instru- ment, do not apply more than 5OVdc to the input when autorange is enabled (unless an external series resistor to limit current to 3mA is used). Zero Check and Correct ZERO SHIFT CHECK ? ? CORRECT When zero check is enabled, the inp

7、ut amplifier is inter- nally disconnected from the input connector of the instru- ment. A 1 OOkG resistor shunts the input connector, and the instrument displays the offset of the selected range. When zero correction is performed, the offset is meas- ured and algebraically subtracted from every subs

8、equent reading (including zero checked readings). Zero check is enabled by pressing ZERO CHECK. Pressing ZERO CHECK a second time disables the fea- ture. 9 When zero correction is performed, only the present range is zero corrected. Before making measurements, it is recommended that each current ran

9、ge be zero cor- rected. To perform zero correction: 1. Enable zero check. 2. To perform zero correction, press SHIFT and then CORRECT in that order. Filters SHIFT cl Filtering is used to stabilize noisy measurements. The Model 486/487 has two available filters; a digital filter and an analog filter.

10、 The digital filter bases the reading on the weighted average of a number of measurement conver- sions. The analog filter is a simple RC filter whose time constant varies with the selected range. When the filter is enabled, the selected filter(s) (digital fil- ter, analog filter or both) will be use

11、d. 10 To check or change the filter selection: Press SHIFT and then FILTER SELECT in that or- der. One of the following messages will be dis- played to indicate the currently selected filter(s): FILTER DIGITAL FILTER ANALOG FILTER DIG+AN (Digital filter selected) (Analog filter selected) (Both digit

12、al and analog filters selected) To select a different filter, use the rotary knob or the 4 and b keys to display the desired filter selection. Enter the displayed filter selection by pressing SHIFT and then FILTER SELECT. Rel REL ? ? The rel (relative) feature serves as a means of baseline suppressi

13、on by allowing a stored offset value to be sub- tracted from subsequent readings. When rel is enabled, the instrument takes the currently displayed reading as a baseline value. All subsequent readings represent the difference between the applied signal level and the stored baseline. 11 A baseline ca

14、n be established for both current and VII ohm measurements and is “remembered” by both func- tions. Rel is enabled by pressing the REL key. Pressing REL a second time disables the feature. Making Current Measurements To make current measurements: 1. Select a current range that is appropriate for the

15、 ex- pected measurement or enable autorange (press SHIFT and then AUTO RANGE). 2. Enable zero check and, if the display is not zeroed, perform zero correction by pressing SHIFT and then CORRECT. 3. Connect the current to be measured to the input of the Model 486/487 (see Figures 1 and 2). 4. Disable

16、 zero check and read the measured current on the display of the Model 486/487. 12 Input Connector Max Overload 2nA - 2pA Range; 35OVdc 2OpA - 2mA Range; 50 Vdc Chassis Gmund Fiaure 1. Triax InDut Connector (3-Lua) Figure 2. Picoammeter Connections Model 486 VOLTAGE SOURCE (Model 487) CAUTION The vol

17、tage source may float. However, neither V-Source terminal may ever be more than 500V above chassis. V-SOURCE OUTPUT 500V MAX TO , lug Cables HI r - 7 -%-I Safety 1 Shield Model 487 Figure 4. Basic V-Source Connections 18 V/I OHMS MEASUREMENTS (Model 487) By using the V-Source in conjunction with its

18、 picoamme- ter, the Model 487 can make resistance measurements as high as 5.05 x 10i6fI. With V/I ohms selected, the re- sistance is automatically calculated from the applied volt- age and measured current (R=V/I) and displayed (in ohms) on the Model 487. The V/I ohms function is enabled by pressing

19、 SHIFT and then OHMS. To make VA ohms measurements: 1. 2. 3. 4. 5. 6. 7. 8. With zero check enabled and the V-Source in standby, connect the circuit shown in Figure 5. Select a current range that gives the nearest full scale reading or autorange, and perform zero cor- rection by pressing SHIFT and t

20、hen CORRECT. Set the V-Source to OV on Ihe range that will be used and press OPERATE to enable the source output. Press REL to cancel offset current. Set the V-Source to the desired voltage level. Disable zero check. The current measurement will be displayed. Enable V/I ohms by pressing SHIFT and th

21、en OHMS. To measure from a baseline resistance, enable ref while in V/I ohms. 19 Figure 5. V/I Ohms Connections (Source V Measure I) 20 MENU The menu items are listed in Table 4. In general, each press of the MENU key displays a menu item in the order shown in the table. The available selections of

22、the dis- played menu items are selected and displayed with the rotary knob or the4 and, keys. The displayed option of the displayed menu item is selected by again pressing MENU. To exit the menu, press SHIFT and then EXIT. Table 4. MENU items Menu Item 1 Description DATA STORE DATA RECL ILIMIT INTEG

23、RATE IEEE-488 DEFAULTS SELFTEST DEBUG CALIBRATE CAL V SRC Arm data store and set buffer size Recall data stored in buffer Set current limit; 25tA or 2.5mA (Model 487 only) Set integration period; fast or line cycle (50 or 60Hz) Set IEEE-488 address O-30 or se- lect Talk-only Save steps as power-up d

24、efaults, return to previously saved defaults, or return to factory defaults Test display and memory elements Troubleshooting mode Calibrate current range Calibrate V-Source (Model 487 only) 21 FRONT PANEL TRIGGERING Trigger Setups In general, trigger setup (mode, internal, delay and I . . . sources)

25、 Is penormea ay: 1. Press SETUP to display the setup. 2. Use the rotary knob to display the desired option of the setup. 3. Press SHIFT and then SETUP to select the dis- played setup. Trigger Mode In the one-shot mode, a separate trigger is required to in- itiate each reading. For the multiple mode,

26、 however, only a single trigger is required. 22 Trigger Interval Determines the time period between individual readings when the instrument is in the multiple trigger mode. The trigger interval can be set from 1Omsec to 999.999sec. Trigger Delay Time from the trigger point until the unit takes a rea

27、ding. In the multiple trigger mode, the delay period affects only the first conversion; however in the one-shot trigger mode, the delay period affects every conversion. The Model 4861487 can be programmed for adelay inter- val from Osec to 999.999sec in 1 msec increments. Trigger Sources Available t

28、rigger source selections: TRIG SRC EXTERNAL TRIG SRC OPERATE TRIG SRC BUS X TRIG SRC GET TRIG SRC TALK 23 EXTERNAL TRIGGERING EXTERNAL METER TRIGGER COMPLETE INPUT OUTPUT Figure 6. Trigger Connectors Triggers on Figure 7. External Trigger Pulse Specifications 24 Figure 8. Meter Complete Specificatio

29、ns 25 DATA STORE OPERATION Storing Data 1. Set the trigger mode, interval and delay. 2. Arm data store and set buffer size as follows: A. Press MENU until the data store is selected, and use the rotary knob to display the follow- ing: DATA STORE YES B. Press MENU to display buffer size. C. Use the r

30、otary knob or thedand, keys to dis- play the desired buffer size value. D. Press MENU. 3. Press TRIGGER to initiate storage. Recalling Data 1. Press MENU until data recall is selected, and use the rotary knob to display the following message: DATA RECL YES 2. Press MENU. The reading stored in the fi

31、rst mem- ory location will be displayed. 3. For sequential access, use the rotary knob. 4. To access a reading at a particular memory loca- tion, adjust the display to the desired location value. 5. To exit data recall, press SHIFT and then EXIT. 26 ANALOG OUTPUT The Model 4861487 has a non-invertin

32、g analog output. For a 200,000 count input, the analog output will be 2V. 27 TALK-ONLY In talk-only, the Model 486/487 will talk continuously on the IEEE-488 bus and output readings to a listen-only de- vice whenever a measurement conversion occurs. To place the Model 4861487 in talk-only: 1. Press

33、and release MENU until the present IEEE-488 selection is displayed. 2. Use the rotary knob to display talk-only as follows: IEEE-488 TALK ONLY 3. Press MENU. The TALK indicator will turn on. 4. Exit the menu by pressing SHIFT and then EXIT. 28 IEEE-488 PROGRAMMING Device-dependent Commands Ml Readin

34、g Source Readings from A/D Single reading From data store All readings from data store Maximum reading from data store Minimum reading from data store Zero Check and Correct Disable zero check Enable zero check Enable zero check and perform zero cor- rection 29 Display Da Display up to 18 character

35、(a) message D Cancel display mode V/I Ohms Disable V/I ohms Enable V/I ohms 1 Data Format G4 G5 G8 G7 ASCII rdgs with prefix ASCII rdgs without prefix ASCII rdgs and buffer locations with prefix ASCII rdgs and buffer locations without prefix Binary rdgs: IEEE Std 754 single-preci- sion, bytes revers

36、ed for Intel CPUs Binary rdgs: IEEE Std 754 single-preci- sion, bvtes in normal order for Motorola CPUS - Binary rdgs: counts and exponent, bytes reversed for Intel CPUs Binary rdgs: counts and exponent, bytes in normal order for Motorola CPUs 30 Hit Control L-L Hit DISPLAY INTENSITY key Hit LOCAL k

37、ey E Hit SHIFT key Hit MENU key K Hit ZERO CHECK key Hit FILTER key H7 Hit RANGEI key H8 Hit REL key HQ Hit RANGEAkey H10 Hit SETUP key Hi1 Hit TRIGGER key H12 Hit OPERATE key (487) H13 !$FtESET key (487) Hi4 HI5 Hit H16 R Hit otary Knob counterclockwise Hi7 Hit Rotary Knob clockwise Self-Test Perfo

38、rm ROM/RAM self-test Perform disalav and ROM/RAM self-test i EOI and Bus Hold-off I 1; EnableEOIandbushold-offonX 1 Disable EOI enable bus hold-off on X Enable EOI, disable bus hold-off on X Disable both EOI and bus hold-off on X 31 Default Conditions or Calibration LO ki L3,V L4 L5 L6 Return to fac

39、tory default conditions and save (L-f) Save present states as default conditions Return to saved default conditions Calibrate present measurement range using “v”; v=-2mA to +2mA Calibrate zero on present voltage source range (Model 487 only) Calibrate full scale on present voltage source range (Mode

40、l 487 only) Prepare to calibrate present voltage source range (Model 487 only) SRQ K M2 Ii: Ml6 M32 Ml28 Disable SRQ Reading overflow Data store full Data store half full Reading done Ready Error Voltage Source Error (Model 487 only) Arm data store; set buffer size W where 32 Disable digital and ana

41、log filters g Enable digital filter; disable analog filter Disable digital filter; enable analog filter Enable digital and analog flters I Range Enable autorange Select 2nA range Select 20nA range Select 200nA range Select 2juI range Select 2OpA range Select 200pA range Select 2mA range No range No

42、range Disable autoranoe Place voltage source in operate 33 I lntearation I Fast integration; 1.6msec at 4-112 digit or 2Omsec (5OHz) at 5-l/2 digit resolution Trigger TO T: T3 z G T8 TQ Multiple on Talk One-shot on Talk Multiple on GET One-shot on GET Multiple on X One-shot on X Multiple on External

43、 Trigger One-shot on External Trigger Multiple on Operate (487) One-shot on Operate (487) Status Send machine status word Send error status word Send model number and firmware revi- sion Send calibration value Send interval Send delay Send relative value for current Send relative value for V/I ohms

44、Send voltage source value (487) Send voltage source error status word (487) 34 I Voltaae Source 14871 I Vn,r,l Specify voltage source level “n” in volts, range “r” and limit “I” n: -505 to 505 r: 0 = 50V range; 1 = 500V range I: 0 = 2OuA limit: 1 = 2mA limit i Delav Wn Delay trigger “n” Execute X Ex

45、ecute other device-dependent com- mands Terminator ?Y CR LF LF CR E CR LF Y4 Nnnn 35 Relative E Disable relative Enable relative using present reading as baseline z2,V Enable relative using V as baseline; v = -2mA to +2mA for current = On to 50.5PR for V/I ohms 23 Enable relative using the baseline

46、previ- ously defined Data Formats Finure 9. ASCII Data Format (G2: Prefix and Suffix) 36 G5 Format (Normal order ; MotMok CPU) Header * Reading * A- 68yies 1 Bylei Byte2 Byle3 Byte4 a- l II I I sign Exponent Manlksa (1 Bii (SB%s) (23 Bits) (single preciston, IEEE-75-4) G4 Format (Reverse mier : lnle

47、l CPU) : Fleading bytes sem in reverse order: i-leader. Byte 4. Byte 3, Byte 2. Byte 1 Headers Rr IJm G4 and G5 fcxmak are shown in FQ. 4.4 * When remllinp data from the huller. one header k l “Last pressed key DISPLAY INTENSITY (A) D=Normal 1 -Dim z=off READING SOURCE (B) O=AfD Reading 1 -One data

48、store reading 2=All data store reading 3=Max data store reading 4=Min data store reading ZERO CHECK and CORRECT (C) O-Zero check disabled I-Zero check enabled VII OHMS (F) 0-W Ohms disabled 1-W Ohms enabled DATA FORMAT(G) O=Rdg with prefix (ASCII) 1 =Rdg without prefix (ASCII) 2=Rdg and buffer locat

49、ion with prefix (ASCII) 3=Fidg and buffer location wifhout prefix (ASCII) 4=Binary rdg - IEEE Std 754 single - $ecfslon, bytes reversed for Intel CPUs B-Binary Rdg - IEEE Sfd 754 singie - f?reclsion, bytes in normal order for Motorola CPUS B=Binary Rdg -counts and exponent, bytes re- versed for Intel CPUs 7=Binary Rdg -