Keithley 2520 User Manual Download Page 55

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Model 2520 User’s Manual

Connections

2-5

Signal connectors

Figure 2-2

shows the location of the signal connectors on the front panel of the testhead.

These connectors are further described below.

Figure 2-2

Testhead signal connectors

CURRENT

OUTPUT

VOLTAGE

SENSE

CAT I

DETECTOR 1

DETECTOR 2

BIAS

CURRENT

INPUT

ISOLATION FROM EARTH: 10V MAX.

Model 2520 Testhead

Detector

Connectors

Laser Diode

Connectors

Summary of Contents for 2520

Page 1: ...Model 2520Pulsed Laser Diode Test System User s Manual A G R E A T E R M E A S U R E O F C O N F I D E N C E ...

Page 2: ...ECT 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 Keithley Instruments ...

Page 3: ...Model 2520 Pulsed Laser Diode Test System User s Manual 2001 Keithley Instruments Inc All rights reserved Cleveland Ohio U S A Third Printing March 2003 Document Number 2520 900 01 Rev C ...

Page 4: ... are numbered sequentially When a new Revision is created allAddenda 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 history page Revision A Document Number 2520 900 01 June 2001 Revision B Document Number 2520 900 01 August 2001 Revision C Document Number 2520 900 01 March 2003 All Kei...

Page 5: ...nected 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 localAC 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 s...

Page 6: ...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 conn...

Page 7: ...liarization 1 9 Front panel summary 1 9 Rear panel summary 1 10 Power up 1 11 Line voltage 1 11 Line power connection 1 11 Power up sequence 1 11 System identification 1 12 Fuse replacement 1 12 Display 1 13 Display format 1 13 Display example 1 13 Display units 1 13 Status and error messages 1 13 Remote display programming 1 14 Front panel display tests 1 14 Default settings 1 14 Saving and resto...

Page 8: ...ties 3 2 Laser diode source and measure ranges 3 2 Laser diode source compliance 3 3 Photodiode source and measure capabilities 3 3 Photodiode source and measure ranges 3 4 Basic circuit configuration 3 5 Polarity 3 6 Laser diode current source polarity 3 6 Laser diode voltage measurement polarity 3 7 Detector measurement polarity 3 8 Voltage bias polarity 3 8 Configuring sources 3 9 Editing sourc...

Page 9: ... 7 Observe readings on the display 4 5 Step 8 Turn source outputs off 4 5 Remote laser diode testing 4 5 Laser diode test commands 4 5 Programming example 4 7 5 Source Measure Concepts Pulse concepts 5 2 Overview 5 2 Delay pulse cycle 5 2 Delay phase 5 3 Pulse phase 5 3 Duty cycle 5 3 Front panel pulse parameters 5 4 Fixed mode 5 4 Staircase sweep mode 5 4 Remote pulse parameters 5 6 Fixed mode 5 ...

Page 10: ...7 Power 6 7 MX B 6 7 Delta remote only 6 7 Front panel math functions 6 8 Math configuration menu 6 8 Programming math functions 6 8 Remote math functions 6 9 Math function commands 6 9 Math function programming example 6 10 7 Sweep Operation Sweep types 7 2 Linear staircase sweep 7 2 Logarithmic staircase sweep 7 3 Custom sweep 7 4 Configuring and running a sweep 7 5 Front panel sweep operation 7...

Page 11: ... 7 Remote triggering 8 9 Trigger model remote operation 8 9 Idle and initiate 8 9 Event detection 8 11 Input triggers 8 11 Delay and pulse phases 8 12 Delay phase 8 12 Pulse phase 8 12 Filtering 8 12 Sweep points 8 12 Counter 8 12 Output trigger 8 13 GPIB defaults 8 13 Operation summary 8 13 Remote trigger commands 8 13 Remote trigger example 8 14 9 Digital I O Port Interlocks and Pulse Sync Outpu...

Page 12: ... 2 GPIB operation 10 3 GPIB standards 10 3 GPIB connections 10 4 Primary address 10 6 General bus commands 10 6 REN remote enable 10 7 IFC interface clear 10 7 LLO local lockout 10 7 GTL go to local 10 7 DCL device clear 10 7 SDC selective device clear 10 8 GET group execute trigger 10 8 SPE SPD serial polling 10 8 Front panel GPIB operation 10 8 Error and status messages 10 8 GPIB status indicato...

Page 13: ...10 17 RS 232 connections 10 18 Error messages 10 20 Programming example 10 20 11 Status Structure Overview 11 2 Status byte and SRQ 11 2 Status register sets 11 2 Queues 11 2 Clearing registers and queues 11 4 Programming and reading registers 11 5 Programming enable registers 11 5 Reading registers 11 6 Status byte and service request SRQ 11 7 Status byte register 11 8 Service request enable regi...

Page 14: ... OPT option query 12 4 SAV NRf save 12 4 RCL NRf recall 12 4 SAV RCL programming example 12 5 RST reset 12 5 TRG trigger 12 5 TRG programming example 12 5 TST self test query 12 6 WAI wait to continue 12 6 13 SCPI Signal Oriented Measurement Commands Command summary 13 2 Acquiring readings 13 2 FETCh 13 2 SENSe 1 DATA LATest 13 3 SENSe2 DATA LATest 13 3 SENSe3 DATA LATest 13 3 READ 13 3 MEASure 13...

Page 15: ...ist 14 23 TRACe data elements 14 24 TRACe item list 14 24 SOURce4 name 14 25 Byte order 14 25 BORDer name 14 25 Status register format 14 26 SREGister name 14 26 OUTPut subsystem 14 27 Turn sources on or off 14 27 STATe b 14 27 Interlock status 14 27 TRIPped 14 27 SENSe subsystem 14 27 Select laser diode voltage measurement range 14 28 UPPer n 14 28 Select detector current measurement range 14 28 ...

Page 16: ...n 14 34 LOW n 14 34 Set voltage limit 14 35 PROTection LEVel NRf 14 35 Select source polarity 14 35 POLarity name 14 35 Set pulse times 14 36 DELay n 14 36 WIDTh n 14 36 TRANsition STATe b 14 36 Configure sweeps 14 37 SPACing name 14 37 STARt n 14 37 STOP n 14 37 CENTer n 14 38 SPAN n 14 38 STEP n 14 39 POINts n 14 40 DIRection name 14 40 Configure list 14 41 CURRent NRf list 14 41 APPend NRf list...

Page 17: ...4 49 Program event enable registers 14 49 ENABle NDN or NRf 14 49 Read condition registers 14 50 CONDition 14 50 Select default conditions 14 50 PRESet 14 50 Error queue 14 50 NEXT 14 50 CLEar 14 50 ENABle list 14 51 DISable list 14 51 SYSTem subsystem 14 51 Default conditions 14 51 PRESet 14 51 POSetup 14 52 Error queue 14 52 NEXT 14 52 ALL 14 52 COUNt 14 53 CODE NEXT 14 53 CODE ALL 14 53 CLEar 1...

Page 18: ...n 14 58 SOURce name 14 58 TIMer n 14 59 ILINe NRf 14 60 OLINe NRf 14 60 OUTPut name 14 60 A Specifications B Status and Error Messages Introduction B 2 Status and error messages B 2 Eliminating common SCPI errors B 7 113 Undefined header B 7 410 Query INTERRUPTED B 7 420 Query UNTERMINATED B 8 C Data Flow Introduction C 2 Buffers C 2 SENS1 SENS2 and SENS3 C 3 INIT C 3 FETCh C 3 READ and MEASure C ...

Page 19: ... E 2 F Measurement Considerations Optimizing laser diode connections F 2 Current pulse output circuit model F 2 Cable inductance F 3 Increasing cable length F 5 Exposed loop area F 6 Sense lead connections F 8 Magnetic coupling F 10 Increasing laser diode pulse measurement speed F 11 Overview F 11 Laser diode impedance matching F 12 Model 2520 output circuit model F 13 Transmission line model F 14...

Page 20: ...Trigger on talk G 4 Message available G 4 General operation notes G 4 H Example Programs Introduction H 2 Hardware requirements H 2 Software requirements H 2 General program instructions H 2 Laser diode test program H 3 Linear staircase sweep program H 4 List sweep program H 5 I Continuous Pulse Mode Continuous pulse mode I 2 Pulse test advantage I 2 Duty cycle I 2 Configuring the 2520 to use Cont...

Page 21: ...iode measure polarity 3 7 Figure 3 4 Detector current measurement polarity 3 8 4 Laser Diode Testing Figure 4 1 Circuit configuration for laser diode testing 4 3 5 Source Measure Concepts Figure 5 1 Delay pulse cycle 5 2 Figure 5 2 Front panel fixed mode pulse parameters 5 4 Figure 5 3 Front panel staircase sweep mode pulse parameters 5 5 Figure 5 4 Front panel staircase sweep mode DC parameters 5...

Page 22: ...ation 9 4 Figure 9 4 Interlock operation 9 6 Figure 9 5 Pulse sync output waveform 9 8 Figure 9 6 Pulse sync out connections 9 9 10 Remote Operations Figure 10 1 IEEE 488 connector 10 4 Figure 10 2 IEEE 488 multi unit test system connections 10 4 Figure 10 3 IEEE 488 and RS 232 connector location 10 5 Figure 10 4 RS 232 interface connector 10 18 11 Status Structure Figure 11 1 Model 2520 status re...

Page 23: ... loop F 7 Figure F 7 Sense lead connections F 8 Figure F 8 Response of 2A pulse with sense leads 1 4 inch away from DUT F 9 Figure F 9 Magnetic coupling F 10 Figure F 10 Optical pulse propagation through differing indices of refraction F 11 Figure F 11 Model 2520 output circuit model F 13 Figure F 12 Minimal impedance mismatch F 14 Figure F 13 Compromised shield provides laser diode access F 14 Fi...

Page 24: ... example 3 14 4 Laser Diode Testing Table 4 1 Source and measure configuration menus 4 2 Table 4 2 Laser diode test commands 4 6 Table 4 3 Basic laser diode test command sequence 4 8 6 Range Filter and Math Table 6 1 Laser diode voltage measurement ranges 6 2 Table 6 2 Photodiode current measurement ranges 6 2 Table 6 3 Laser diode current source ranges 6 3 Table 6 4 Range commands 6 3 Table 6 5 R...

Page 25: ...dition register commands 11 17 Table 11 6 Event register commands 11 17 Table 11 7 Event enable registers commands 11 18 Table 11 8 Program and read register programming example 11 19 Table 11 9 Error queue commands 11 21 12 Common Commands Table 12 1 IEEE 488 2 common commands and queries 12 2 Table 12 2 OPC programming example 12 4 Table 12 3 SAV RCL programming example 12 5 Table 12 4 TRG progr...

Page 26: ...D 2 Hexadecimal and decimal command codes D 10 Table D 3 Typical addressed multiline command sequence D 12 Table D 4 Typical addressed common command sequence D 12 Table D 5 IEEE command groups D 13 Table D 6 Model 2520 interface function codes D 14 E IEEE 488 and SCPI Conformance Information Table E 1 IEEE 488 documentation requirements E 3 Table E 2 Coupled commands E 4 F Measurement Considerati...

Page 27: ...the Model 2520 Pulsed Laser Diode Test System Familiarization Summarizes the controls and connectors on the unit Power up Covers line power connection line voltage settings fuse replace ment and the power up sequence Display Provides information about the Model 2520 display Default settings Covers factory default setups and saving and recalling user set ups Menus Covers the main and configuration ...

Page 28: ...h the manual Be sure to note these changes and incorporate them into the manual Specifications Model 2520 specifications shown throughout the body of this manual and the detailed specifications listed in Appendix A were current at the time of printing but they are sub ject to change without notice For the most recent specifications refer to the web site at www keithley com Safety symbols and terms...

Page 29: ...anual If an additional user s manual is required order the appropriate manual package for example 2520 900 00 The manual packages include a manual and any pertinent addenda Options and accessories The following options and accessories are available from Keithley for use with the Model 2520 Signal cables and adapters CA 289 1A Cable This 1m low noise triax cable is terminated at one end with a 3 sl...

Page 30: ...gger cable Lets you connect Trigger Link lines one Volt meter Complete and two External Trigger of the Model 2520 to instruments that use BNC trigger connectors The Model 8503 is 1m long Rack mount kits Model 4288 1 single fixed rack mount kit Mounts a single Model 2520 in a standard 19 inch rack Model 4288 2 side by side rack mount kit Mounts two instruments Models 182 428 486 487 2000 2001 2002 ...

Page 31: ...rrent from 0 7µA to 105mA on each of two channels Source photodiode bias voltage on each of two channels from 0 to 20V Some additional capabilities of the Model 2520 include Sweep capabilities linear and logarithmic staircase and custom sweeps for the laser diode current source Digital I O port to control other instruments Programming language and remote interfaces The Model 2520 uses the SCPI pro...

Page 32: ...photodiode detector 1 current measure DETECTOR 2 keys VB Control photodiode detector 2 bias voltage source IPD Configure photodiode detector 2 current measure EDIT keys Increase value Decrease value Move cursor left Move cursor right COMPL and RANGE keys COMPL Set laser diode source voltage compliance limit RANGE Increase range RANGE Decrease range RANGE COMPL EDIT MATH RANGE EXIT ENTER CONFIG MEN...

Page 33: ...y to configure function or operation MENU Access and configure Main Menu selections When entering numeric data use to clear reading to minimum absolute value EXIT Cancels selection Use to back out of menu structures ENTER Accepts selection Annunciators EDIT Instrument in edit mode ERR Questionable reading invalid cal step MATH Math function enabled REM Instrument in GPIB remote mode TALK Instrumen...

Page 34: ...ital output lines output enable line and start of test signal RS 232 connector RS 232 Connector for RS 232 remote operation Use a straight through not null modem DB 9 cable such as a Keithley Model 7009 5 GPIB connector IEEE 488 Connector for GPIB remote operation Use a shielded cable Keithley Model 7007 1 or 7007 2 Power module Contains the AC line receptacle power on off switch and the power lin...

Page 35: ...ls Center conductor Current input Inner shell Voltage bias source output Outer shell Chassis ground WARNING Isolation from earth is 10V maximum Exceeding this value may result in a shock hazard Laser diode connectors CURRENT OUTPUT Current source HI and LO output terminals to laser diode VOLTAGE SENSE HI and LO sense terminals to measure laser diode voltage BNC connector terminals Center conductor...

Page 36: ...hen disabled source outputs cannot be turned on Glows green when enabled source outputs can be turned on LASER POWER ON Indicates when source outputs are turned on WARNING If at any time the indicators provided on the testhead for INTER LOCK STATUS or LASER POWER ON should fail to light or to properly indicate status immediately contact a Keithley service repre sentative for repair Failure to do s...

Page 37: ...tlets When proper connections 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 3 Turn on the instrument by pressing the rear panel power switch to the on 1 posi tion Power up sequence On power up the Model 2520 performs self tests on its EPROM and RAM...

Page 38: ...to be replaced perform the steps below WARNING Disconnect the line cord and all cables and test leads from the instru ment before changing the line fuse 1 The fuse is located in a holder in the power module adjacent to the AC receptacle Figure 1 2 At the right of the fuse holder is a small tab At this location use a small bladed screwdriver to release the fuse holder 2 Slide the fuse holder out to...

Page 39: ...g information can be displayed using either engineering units or sci entific notation in either fixed or floating point format Use the NUMBERS selection of the main MENU to select the display format as discussed under Menus page 1 17 Engineering units example 12 345mA Scientific notation example 1 23e 2A Annunciators which are located along the top of the reading message display indicate various s...

Page 40: ... pixels of each digit turn on the rows of the top left display digit and turn on all annunciators and pixels of each digit in a sequential manner Press EXIT to cancel this test CHAR SET This test displays special characters Press EXIT to cancel the test See Menus page 1 17 for more menu information Default settings By using appropriate menu selections you can save and recall various instrument set...

Page 41: ...he SET POWER ON DEFAULT menu choose the power on configuration BENCH or GPIB see below or USER SETUP NUMBER 4 If you chose to use a user setup as the power on configuration select the user setup number 0 4 then press ENTER Factory default settings Table 1 3 summarizes BENCH front panel and GPIB remote factory defaults for oper ating modes available from the front panel Some features are available ...

Page 42: ... factor slope 0 0 VL units X X IPD units W W State Disabled Disabled Numbers No effect No effect Output Off Off Power on default No effect No effect Polarity Measure VL Positive Positive Source IL VB Positive Positive Range measure VL 10V 10V IPD 100mA 100mA RS 232 No effect No effect Sources IL mode Fixed Fixed IL function Pulse Pulse IL range 500mA 500mA IL amplitude 0A 0A IL low amplitude 0A 0A...

Page 43: ...onfiguration using SYSTem POSetup Section 14 Menus The following paragraphs discuss the main menu operation menus configuration menus and rules to navigate menus Setting BENCH default GPIB default Sweeps IL only Type None None Direction Up Up Sweep points 1000 1000 Start 0A 0A Stop 0A 0A Step 0A 0A Center 0A 0A Span 0A 0A Triggering Trigger input Event Immediate Immediate Timer 0 1 0 1 Input line ...

Page 44: ...bottom line indicates there are one or more additional items or messages to select from Use the appropriate cursor key to display them Table 1 4 Main menu Menu item1 Description CAL2 UNLOCK EXECUTE VIEW DATES SAVE CHANGE PASSWORD TIMESTAMP TEST DISPLAY TESTS3 KEYS DISPLAY PATTERNS CHAR SET SERIAL NUMBERS Calibrate Model 2520 Unlock calibration Execute calibration View last and next calibration dat...

Page 45: ... at the selected digit Use the key to change source value polarity regardless of cursor position Boolean selections such as ON OFF and HIGH LOW are toggled by placing the cursor on the selection and pressing an EDIT or or RANGE or key A change is only executed when ENTER is pressed Entering an invalid parameter generates an error and the entry is ignored However entering an out of range value too ...

Page 46: ...or 8 PARITY Set parity NONE ODD or EVEN TERMINATOR Select terminator CR CR LF LF LF CR FLOW CTRL Select flow control NONE or XON XOFF SETUP Save and recall factory and user setups SAVESETUP MENU Setup menu SAVE Save user setups 0 4 RESTORE Restore user setups POWERON Set power on configuration BENCH Use BENCH defaults as power on GPIB Use GPIB defaults as power on USER SETUP NUMBER User setup 0 4 ...

Page 47: ...ing CONFIG then LASER VL DETECTOR 1 IPD or DETECTOR 2 IPD Configuration menus which are summarized in Table 1 7 through Table 1 9 are available for the following operating modes Measure and source functions LASER and DETECTOR keys Table 1 7 TRIG and FILTER Table 1 8 SWEEP and MATH Table 1 9 These various configuration menus are covered in detail in the pertinent sections of this manual Table 1 6 P...

Page 48: ...or 1 measurement polarity POSITIVE Select positive measurement polarity NEGATIVE Select negative polarity CONFIG DETECTOR 2 IPD Configure photodiode detector 2 measurement CHANNEL3 POLARITY Select photodiode 2 measurement polarity POSITIVE Select positive measurement polarity NEGATIVE Select negative polarity CONFIG LASER IL Configure laser diode voltage current source CONFIGURE I SOURCE POLARITY ...

Page 49: ...ection event IMMEDIATE Immediate event detection GPIB GPIB GET or TRG TIMER After timer interval elapses enter interval MANUAL Front panel TRIG key TLINK Enter trigger link line 1 6 and state STEST When Digital I O SOT is pulsed low STEST When Digital I O SOT line is pulsed high STEST When Digital I O SOT line is pulsed either high or low TIMER Set trigger timer interval TRIGGER OUT Configure outp...

Page 50: ...LOG Log staircase sweep program START STOP NO OF POINTS SWEEP COUNT Set sweep count FINITE Program sweep count value INFINITE Never ending sweep CONFIG MATH Configure math functions CONFIGURE MATH CHANNEL1 Program VL laser diode voltage math function I V Select conductance function IL VL V I Select resistance function VL IL MX B_UNIT Select MX B function program M B and units P Select power functi...

Page 51: ...locations of the signal jacks used for laser diode and photodiode source and measurement and details the terminal configuration of the triax connectors on the testhead Interlock connections Details connections to the remote interlock circuit which is used to inhibit the outputs with external switching Laser diode test connections Provides detailed diagrams for connecting the Model 2520 signal conn...

Page 52: ...d to prevent operation unless authorized by the responsible body This requirement must be part of the facilities administrative controls for laser safety When servicing the test system any required personnel protection equipment e g laser safety goggles must be provided by the cus tomer s responsible body The customer s laser safety officer LSO must review and approve all installations before bein...

Page 53: ...t force air heated or not into or onto its surfaces or cooling vents This addi tional airflow could compromise accurate performance Make sure there is adequate airflow around the bottom and sides to ensure proper cooling Adequate airflow enables air tempera tures within approximately one inch of the testhead surfaces to remain within specified limits under all operating conditions Testhead connect...

Page 54: ...VA MAX TESTHEAD CONN 2 CAT I WARNING NO INTERNAL OPERATOR SERVICABLE PARTS SERVICE BY QUALIFIED PERSONNEL ONLY CAUTION FOR CONTINUED PROTECTION AGAINST FIRE HAZARD REPLACE FUSE WITH SAME TYPE AND RATING MADE IN U S A IEEE 488 CHANGE IEEE ADDRESS WITH FRONT PANEL MENU DIGITAL I O RS 232 Model 2520 Mainframe Model 2520 Testhead CONN 2 Cable CONN 1 Cable MAINFRAME CONN 1 MAINFRAME CONN 2 REMOTE INTER...

Page 55: ...signal connectors on the front panel of the testhead These connectors are further described below Figure 2 2 Testhead signal connectors CURRENT OUTPUT VOLTAGE SENSE CAT I DETECTOR 1 DETECTOR 2 BIAS CURRENT INPUT ISOLATION FROM EARTH 10V MAX HI HI LO LO Model 2520 Testhead Detector Connectors Laser Diode Connectors ...

Page 56: ...NSE are BNC jacks used for making connec tions to the laser diode under test CURRENT OUTPUT HI and LO provide current source connections to the DUT while VOLTAGE SENSE HI and LO sense the voltage across the DUT Note that the center pin of each connector is signal while the outer shell is chassis ground Interlock connections The Model 2520 has two interlock circuits a remote interlock and a key int...

Page 57: ...gure 2 4 Connections are as follows The center conductors of the CURRENT OUTPUT and VOLTAGE SENSE HI and LO terminals connect to the laser diode under test Current is applied to the laser diode through the CURRENT OUTPUT HI and LO terminals and voltage across the DUT is measured through the VOLTAGE SENSE HI and LO terminals DETECTOR 1 connects to the forward detector photodiode The CURRENT INPUT c...

Page 58: ...nt flowing into the ammeter center conductor of the DETECTOR triax con nector is negative while current flowing out is positive For laser diode voltage VL measurements the measurement is positive when the HI terminal is at a higher polarity than the LO terminal and negative when the HI terminal is at a lower polarity than the LO terminal CURRENT OUTPUT VOLTAGE SENSE CAT I DETECTOR 1 DETECTOR 2 BIA...

Page 59: ...Ω 1MΩ V Bias VOLTAGE SENSE Optional Earth Ground CURRENT OUTPUT Reverse Relay Shorting Relay 12 Bit DAC 12 Bit DAC 16 Bit DAC 25V DETECTOR 1 Photodiode 1 Laser Diode V Clamp Low DAC I DAC V Measure I Measure 14 Bit A D V Bias DETECTOR 2 Photodiode 2 I Measure Current Source Triax Cable Triax Cable BNC Coaxial Cables HI LO HI LO ...

Page 60: ...ble shields together at the DUT Carry cable shields as close to the DUT as possible Minimize the length of exposed unshielded signal lines Dress the VOLTAGE SENSE cables as far away from the CURRENT OUTPUT cables to avoid magnetic coupling Twist the SENSE cables together to further reduce magnetic coupling Connect the VOLTAGE SENSE leads as close to the body of the DUT as possible NOTE See Appendi...

Page 61: ... ranges compliance and fundamental measurement and voltage bias circuit configuration Configuring sources Covers setting up the laser diode current source and photodiode voltage bias source values Configuring measurements Covers setting up both laser diode voltage and photodiode current measurements ...

Page 62: ... the responsibility of the customer to operate instruments in a safe manner Follow all applicable safety regulations for installing config uring and using the Model 2520 The Model 2520 as installed should be approved by the appropriate safety personnel such as the responsi ble Laser Safety Officer or equivalent Suggested starting points for workplace regulations and standards ANSIZ136 1 IEC 825 OS...

Page 63: ...ompliance conditions over the GPIB Section 11 The compliance voltage is sensed at the pulser circuit board so any I R drops in the cables or connections is not sensed and no corrections are made for these resistances Photodiode source and measure capabilities Each Model 2520 photodiode channel has the following current measurement and voltage bias capabilities Measure Current Each Model 2520 photo...

Page 64: ...surement ranges resolutions and maxi mum readings Note that each photodiode voltage bias source has a single 20V range See Section 6 for more details on ranging Table 3 3 Photodiode current measurement ranges Current range Maximum resolution Maximum reading 10mA 0 7µA 10 5mA 20mA 1 4µA 21mA 50mA 3 4µA 52 5mA 100mA 6 8µA 105mA ...

Page 65: ... In addition to the laser diode current source and voltage measurement circuits the unit has two separate photodiode channels each of which includes a feedback ammeter and a 0 20V voltage bias source Figure 3 1 Basic circuit configuration A A V Model 2520 Source Current Measure Voltage Source Voltage Measure Current Source Voltage Measure Current Laser Diode Detector 1 Detector 2 Optional Earth Gr...

Page 66: ...ve current source polarity With the positive polarity shown in A current across the DUT develops a voltage such that the pos itive DUT terminal is connected to CURRENT OUTPUT HI and the negative DUT termi nal is connected to CURRENT OUTPUT LO With the negative polarity shown in B the negative DUT terminal is connected to CURRENT OUTPUT HI and the positive termi nals is connected to CURRENT OUTPUT ...

Page 67: ...e voltage measurements are essentially unipolar and the polarity set ting must agree with the polarity connections of the laser diode If the polarity is set incorrectly an overflow reading will be displayed In order to reduce common mode errors in voltage measurements connect the HI voltage measurement terminal to the same terminal as current source HI and connect the LO volt age measurement termi...

Page 68: ...he photodiode If the polarity is set incorrectly an overflow reading will be displayed Voltage bias polarity The voltage bias outputs are bipolar and there is no separate polarity setting Simply set the voltage bias value to the desired value in the range of 20V This bias voltage value will be output on the inner shield of the detector triax jack relative to the center conductor terminal For examp...

Page 69: ...ited and the EDIT annunciator will turn on while in the edit mode If no key is pressed within a few seconds the edit mode will be cancelled automatically COMPL allows editing of the laser diode current source voltage compliance EDIT and places the display cursor on the display digit to be changed EDIT or increments or decrements the source value Note that pressing either of these keys will automat...

Page 70: ...ield 8 While in the edit mode use the RANGE and keys to select the desired source range 500mA or 5A Use the lowest range possible for best accuracy 9 To simply increment or decrement the displayed source value use the EDIT and keys to place the blinking cursor on the digit to be changed then increment or decrement the value with the EDIT and keys Note that the source value will be updated immediat...

Page 71: ...he desired source range 500mA or 5A 13 Use the EDIT and or numeric keys to set the source amplitude to the desired level For the pulse mode this value will be the high pulse level 14 Press the COMPL key then set the voltage compliance limit to the desired value Press ENTER to complete your selection and return to normal display Setting photodiode detector source values The basic procedure for edit...

Page 72: ...laser diode measurement configura tion menu 2 Choose POLARITY then press ENTER 3 Select POSITIVE or NEGATIVE as desired then press ENTER Figure 3 3 4 Press the LASER VL key 5 Use the RANGE and keys to select the desired measurement range 5V or 10V Use the lowest range possible for best accuracy Configuring photodiode measurements 1 Press CONFIG then either DETECTOR 1 IPD or DETECTOR 2 IPD to acces...

Page 73: ...on limit SOURce 1 FUNCtion function SOURce 1 PULSe DELay delay SOURce 1 PULSe WIDTh width SOURce 1 CURRent LOW low_current SOURce2 VOLTage voltage SOURce3 VOLTage voltage Set laser diode voltage measure range 5 or 10 Set laser diode measure polarity POSitive or NEGative Set detector 1 measure range 0 01 0 02 0 05 0 1 Set detector 1 measure polarity Set detector 2 measure range 0 01 0 02 0 05 0 1 S...

Page 74: ...plitude Table 3 5 Basic source and measure configuration example Commands Comments SENS1 VOLT RANG 10 SENS1 VOLT POL POS SENS2 CURR POL NEG SENS3 CURR POL NEG SOUR1 CURR RANG 0 5 SOUR1 CURR 0 5 SOUR1 VOLT PROT 5 SOUR1 CURR POL POS SOUR1 FUNC PULS SOUR1 PULS DEL 100e 6 SOUR1 PULS WIDT 10e 6 SOUR1 CURR LOW 10e 3 SOUR2 VOLT 20 SOUR3 VOLT 10 Laser diode measure range 10V Laser diode positive measure p...

Page 75: ...he laser diode source as well as all three measurement functions Front panel laser diode testing Provides a detailed procedure for performing laser diode tests from the front panel Remote laser diode testing Summarizes remote commands for testing laser diodes via remote and also gives a programming example ...

Page 76: ...e measurement CHANNEL1 POLARITY Select laser diode measurement polarity POSITIVE Select positive measurement polarity NEGATIVE Select negative polarity CONFIG DETECTOR 1 IPD Configure detector 1 current measurement CHANNEL2 POLARITY Select detector 1 measurement polarity POSITIVE Select positive measurement polarity NEGATIVE Select negative polarity CONFIG DETECTOR 2 IPD Configure detector 2 measu...

Page 77: ...ed drawing Note that connections for laser diode as well as both photodiode detectors are included but the required interlock connections are not shown See Section 2 Connections for detailed signal connection information as well as interlock connections Figure 4 1 Circuit configuration for laser diode testing Source VB Detector 1 A Laser Diode Detector 2 A V Model 2520 Source IL Source VB Measure ...

Page 78: ...or DETECTOR 2 Step 3 Configure laser diode current source Set up the laser diode source as follows 1 Press CONFIG then LASER IL to access the source configuration menu 2 Choose POLARITY then set the polarity to POSITIVE or NEGATIVE as desired 3 Choose SHAPE then select the DC or PULSE mode as desired 4 If you chose PULSE select LOW then set the pulse low amplitude 5 Press EXIT to return to normal ...

Page 79: ...turn on to indicate the outputs are on Press the TRIG key to trigger readings NOTE Interlocks must be enabled before outputs can be turned on See Section 2 Step 7 Observe readings on the display Observe the measurement readings on the display For this example the unit will display laser diode power detector 1 MX B math and detector 2 current on the lower line Step 8 Turn source outputs off When fi...

Page 80: ...r Define laser diode MX B units 1 character ASCII string Request detector 1 math reading Enable disable detector 1 math ON or OFF Set detector 1 MX B B offset parameter Set detector 1 MX B M slope parameter Define detector 1 MX B units 1 character ASCII string Request detector 2 math reading Enable disable detector 2 math ON or OFF Set detector 2 MX B B offset parameter Set detector 2 MX B M slope...

Page 81: ...CURRent MODE FIXed SOURce 1 CURRent RANGe range SOURce 1 CURRent current SOURce 1 CURRent POLarity polarity SOURce 1 VOLTage PROTection limit SOURce 1 FUNCtion function SOURce 1 PULSe DELay delay SOURce 1 PULSe WIDTh width SOURce 1 CURRent LOW low_current SOURce2 VOLTage voltage SOURce3 VOLTage voltage Select fixed not sweep laser diode current source mode Select laser diode source range 0 5 or 5 ...

Page 82: ...R1 CALC2 KMAT MBF 2 CALC2 KMAT MMF 0 5 CALC1 STAT ON CALC2 STAT ON OUTP1 ON READ CALC1 DATA CALC2 DATA OUTP1 OFF Restore GPIB defaults LD measure range 10V LD positive polarity Det 1 negative polarity Det 2 negative polarity Det 2 current data Det 1 10mA range Det 2 50mA range 0 5A LD source range LD source output 0 5A 5V LD source voltage limit LD source positive polarity LD source pulse mode 200...

Page 83: ...urrent source pulse mode Sweep operation Covers the various types of sweeps that can be performed Operating boundaries Covers output and limit operating boundaries for the laser diode current source Data flow Describes measurement readings and how data is stored in the buffer during a sweep ...

Page 84: ...on you can design your own sweep waveforms by using the custom list sweep mode See Sweep waveforms page 5 8 for more sweep information Delay pulse cycle Model 2520 laser diode current source and voltage measurements consist of a series of delay pulse cycles Figure 5 1 During each cycle the following occurs 1 Wait for the programmed delay period 2 Output the programmed current pulse 3 During the cu...

Page 85: ... period For the fixed mode the total delay is the sum of the programmed delay and the trig ger latency Pulse phase During the pulse phase the unit outputs one current pulse at the specified amplitude with the programmed pulse width Sampling on all three measurement channels laser diode voltage detector 1 and detector 2 current is also performed during this phase In the DC mode the readings are tak...

Page 86: ...case sweep mode Figure 5 3 shows how various front panel programming parameters control various stair case sweep pulse waveform aspects These parameters are programmed by pressing the appropriate key Pulse amplitudes determined by the programmed START STOP and STEP or POINTS parameters in the CONFIG SWEEP menu DELAY sets the pulse delay time between pulses PW sets the pulse width LOW This paramete...

Page 87: ...ts These parameters are programmed by pressing the appropriate key Pulse amplitudes determined by the programmed START STOP and STEP or POINTS parameters in the CONFIG SWEEP menu DELAY PW determines the time at each step Figure 5 4 Front panel staircase sweep mode DC parameters PW Delay Start Low Step Stop 0A Returns to 0A because pulse is less than Low PW Readings Taken and Averaged Delay No Read...

Page 88: ...ront panel programming parameters control various stair case sweep pulse waveform aspects These parameters are programmed by sending the appropriate command Pulse amplitudes determined by parameters programmed with SOUR1 CURR STAR SOUR1 CURR STOP and SOUR1 CURR STEP or SOUR1 SWE POINT for LOG sweep commands SOUR1 PULS WIDT sets the pulse width SOUR1 PULS DEL sets the pulse delay time between pulse...

Page 89: ...ix A for details Figure 5 7 Pulse characteristics The rise and fall times of the current source pulse can be controlled with the SOURce1 PULSe TRANsition command as covered in SOURce subsystem page 14 32 This command allows you to increase the rise time of the pulse Increasing the rise time will help reduce overshoot and or oscillations that could occur when long cables are used or if poor connect...

Page 90: ...of the programmed pulse width and pulse delay times for both DC and pulse sweeps See Section 7 for more details on staircase sweep operation See also the SOUR1 CURR and SOUR1 SWE commands under SOURce subsystem page 14 32 for information on programming staircase sweeps via remote Custom sweep The custom sweep lets you construct your own sweep by specifying the number of source measure points 100 m...

Page 91: ...igure 5 9 Custom sweep waveform Start Stop Linear Staircase Sweep Start 100 Logarithmic Staircase Sweep First Point Custom Sweep Last Point 10 1 0 1 Stop Logarithmic scale shown for staircase steps Note DC mode waveforms shown SOUR1 LIST WIDT SOUR1 LIST DEL SOUR1 LIST CURR SOUR1 CURR LOW ...

Page 92: ...UT that is connected to the output Figure 5 11 shows operation examples for resistive loads that are 50Ω and 125Ω respectively For these examples the Model 2520 current source is programmed to source 100mA with a voltage limit of 10 5V In Figure 5 11A the Model 2520 is sourcing 100mA into the 50Ω load and subsequently develops 5V across the load resistance As shown the load line for 50Ω intersects...

Page 93: ...put Current mA Output Voltage V 5V 10 5V 100mA 50Ω DUT Load Line R V I R I V R 100mA 50Ω 5V A Normal Current Source Operation Operating Point Current Source Load Line 10 5V 100mA 10V 125Ω B Current Source in Compliance 80mA 1 2 5 Ω D U T L o a d L i n e R Output Voltage V Output Current mA 80mA Operating Point Voltage Limit Load Line ...

Page 94: ...low for front panel operation is summarized by the block diagrams provided in Figure 5 12 NOTE See Appendix C for remote operation data flow information as well as a diag nostic tool that allows you to access raw samples Basic reading display With sweeps and math disabled Figure 5 12A the Model 2520 displays the configured laser diode voltage and detector current readings Math function display Wit...

Page 95: ...age and Detector Current Functions Math Function Display Normal Voltage and Current Readings Display Math Function Readings Display Buffer Readings with Recall Active B Math Function Enabled C Sweep Enabled Laser Voltage and Detector Current Readings Sweep Buffer A Math Function and Sweeps Disabled ...

Page 96: ...ings and source values and ranging limitations Filter Provides information on the filtering process that can be used to reduce reading noise Math Outlines the math functions that can be performed on laser diode voltage measurement and photodiode current measurement data ...

Page 97: ...nd maximum readings Photodiode detector current ranges Table 6 2 lists the available current measurement ranges resolution values and maximum readings for each Model 2520 photodiode detector NOTE The current measurement range can be individually set for each detector Table 6 1 Laser diode voltage measurement ranges Voltage range Resolution Maximum reading 5V 0 33mV 5 25V 10V 0 66mV 10 5V Table 6 2...

Page 98: ...ges To set the range press the LASER IL and EDIT keys then use the RANGE and keys Remote range programming Table 6 4 summarizes the commands necessary to control range See SENSe subsystem page 14 27 for more details on these commands Table 6 3 Laser diode current source ranges Current range Resolution Maximum output 500mA 10µA 500mA 5A 100µA 5 0A Pulse mode only 1A maximum in DC mode Table 6 4 Ran...

Page 99: ...e delay pulse cycle for each filter sample measurement See Section 5 for delay pulse details The measurement results for all delay pulse cycles are then averaged to give one filtered reading If the filter is enabled in sweep mode See Section 7 each step of the sweep will effec tively be repeated for the filter count number of times Figure 6 1 shows an example of a sweep from 10mA to 30mA with a fi...

Page 100: ...ntrol When filtering is being applied to the measured signals the FILT annunciator will be on The FILTER key is used to control filtering Pressing FILTER turns on the FILT annuncia tor to indicate that the filter configuration is being applied to all three measurements Pressing FILTER a second time turns the FILT annunciator off to indicate that filtering is turned off Remote filter programming Fi...

Page 101: ...re available only for laser diode voltage measurements MX B is available for all three measurement functions laser diode voltage and both detector current measurements Table 6 6 Filter commands Commands Description SENSe 1 AVERage COUNt count SENSe 1 AVERage STATe state SENSe2 AVERage COUNt count SENSe2 AVERage STATe state SENSe3 AVERage COUNt count SENSe3 AVERage STATe state Set average filter co...

Page 102: ...tion calculates power using the measured voltage and source current values as follows Power VL IL where VL laser diode voltage measurement IL laser diode source current MX B This math function multiplies the measured laser diode voltage or photodiode detector current by an offset factor and adds an offset value as follows Reading MX B where M gain slope factor X measured laser diode voltage VL or ...

Page 103: ...only select the math function 4 When programming the MX B function for all three channels enter the M and B values and the units at the successive prompts and press ENTER after each entry Table 6 8 Math configuration menu Configuration menu item Description CONFIGURE MATH CHANNEL1 Program VL laser diode voltage math function I V Select conductance function IL VL V I Select resistance function VL I...

Page 104: ...nits suffix CALCulate 1 STATe state Enable enable laser diode math ON or OFF CALCulate2 DATA Request detector 1 math reading CALCulate2 KMATh MBFactor B Set detector 1 MX B offset B CALCulate2 KMATh MMFactor M Detector 1 MX B slope M CALCulate2 KMATh MUNits units Set 1 character MX B units suffix CALCulate2 STATe state Enable enable detector 1 math ON or OFF CALCulate3 DATA Request detector 2 math...

Page 105: ...10 Math function programming example Command Description CALC1 FORM POWER1 Select laser diode power function CALC1 KMAT MUN W Set W math units CALC1 STAT ON Enable laser diode math CALC2 KMAT MBF 5e 3 Detector 1 MX B offset B 5e 3 CALC2 KMAT MMF 0 5 Detector 1 slope M 0 5 CALC2 STAT ON Enable detector 1 math OUTP1 ON Turn on outputs INIT Trigger math readings CALC1 DATA Request laser diode power r...

Page 106: ...e three basic sweep types Linear staircase logarith mic staircase and custom sweep Configuring and running a sweep Discusses the procedure for setting up and performing sweeps including selecting and configuring a sweep and performing a sweep ...

Page 107: ... to an ending stop current source value Programmable parameters include the start stop and step source current levels This example shows the DC mode of operation When this sweep is triggered to start the current source output will go to the start source current level The output will then change in equal steps until the stop source level is reached The time duration at each step is determined by th...

Page 108: ...orms are shown Figure 7 2 Logarithmic staircase sweep The programmable parameters for a log sweep include the start and stop levels and the number of measurement points for the sweep The specified start stop and point parame ters determine the logarithmic step size for the sweep Step size for the sweep in Figure 7 2 is calculated as follows Stop 10 X X X X X Log Points 5 1 10 5 6234 3 1623 1 7783 ...

Page 109: ...elay Figure 7 3 shows an example of a custom sweep When this sweep is started the output goes to the first current level in the sweep after the delay period The pulse period and time between pulses is determined by the programmed pulse and delay parameters The sweep will continue through the points in the order they were programmed and stop after the last current point The size of the current list...

Page 110: ...taircase sweep is selected you will be prompted to enter the START STOP and STEP levels LOG When the logarithmic staircase sweep is selected you will be prompted to enter the START and STOP levels and specify the NO OF POINTS number of measurement points SWEEP COUNT Use this menu item to specify how many sweeps to perform FINITE Use this option to enter a discrete number of sweeps to perform with ...

Page 111: ...ent ranges by pressing the DETECTOR 1 IPD DETEC TOR 2 IPD and RANGE keys See Section 3 Basic circuit configuration for more information Step 2 Configure sweep Configure the sweep as follows 1 Press CONFIG then SWEEP 2 Select TYPE then press ENTER 3 Select STAIR then press ENTER 4 At the prompts enter the desired START STOP and STEP values 5 From the CONFIGURE SWEEPS menu select SWEEP COUNT press E...

Page 112: ...eys Step 2 Configure sweep Configure the sweep as follows 1 Press CONFIG then SWEEP 2 Select TYPE then press ENTER 3 Select LOG then press ENTER 4 At the prompts enter the desired START STOP and NO OF POINTS values 5 From the CONFIGURE SWEEPS menu select SWEEP COUNT press ENTER then choose FINITE or INFINITE as desired 6 Press EXIT to return to normal display Step 3 Turn outputs on Press the ON OF...

Page 113: ...e 1 CURRent STEP current SOURce 1 CURRent CENTer current SOURce 1 CURRent SPAN current SOURce 1 SWEep SPACing type SOURce 1 SWEep POINts points SOURce 1 SWEep DIRection direction Select staircase sweep mode Specify sweep start current 0 to 5 0 Specify sweep stop current 0 to 5 0 Specify sweep step current 0 to 5 0 Specify sweep center current 0 to 5 0 Specify sweep span current 0 to 5 0 Select sta...

Page 114: ...Linear staircase sweep programming example Command Description RST FORM ELEM VOLT1 CURR2 CURR3 SENS1 VOLT RANG 5 SOUR1 CURR RANG 0 5 SOUR1 CURR STAR 10e 3 SOUR1 CURR STOP 100e 3 SOUR1 CURR STEP 10e 3 SOUR1 CURR MODE SWE SOUR1 SWE SPAC LIN SOUR2 VOLT 5 SOUR3 VOLT 5 OUTP1 ON READ OUTP1 OFF Restore GPIB default conditions Laser diode voltage detector current data 5V measure range 500mA source range 1...

Page 115: ...d I list SOURce 1 LIST CURRent POINts SOURce 1 LIST DELay D list SOURce 1 LIST DELay APPend D list SOURce 1 LIST DELay POINts SOURce 1 LIST WIDTh W list SOURce 1 LIST WIDTh APPend W list SOURce 1 LIST WIDTh POINts SOURce 1 LIST DIRection direction Select current list custom sweep mode Define I source list I1 I2 In 0 to 5 0 100 max points Add I source list value s I1 I2 In 0 to 5 0 100 max Query le...

Page 116: ... SOUR1 LIST CURR 0 2 0 1 0 4 0 3 0 5 SOUR1 LIST DEL 7e 3 4e 3 2e 3 8e 3 1e 3 SOUR1 LIST WIDT 10e 6 50e 6 35e 6 20e 6 60e 6 SOUR2 VOLT 5 SOUR3 VOLT 5 OUTP1 ON READ OUTP1 OFF Restore GPIB default conditions Laser diode voltage detector current data Current list sweep mode Set current sweep points Set pulse delay sweep points Set pulse width sweep points Detector 1 bias 5V Detector 2 bias 5V Turn on ...

Page 117: ...rigger Trigger link Discusses the trigger link including input triggers and output trig gers Configuring triggering Details how to configure the various triggering aspects from the front panel Remote triggering Details the remote trigger model summarizes trigger com mands and gives a basic triggering example ...

Page 118: ...d various input and output trig ger options are available to provide synchronization between the Model 2520 and other instruments via the Trigger Link Unless otherwise noted the programmable aspects of the trigger model are performed from the CONFIGURE TRIGGER menu See Configuring triggering page 8 7 Figure 8 1 Trigger model front panel operation Idle PULSE DELAY No Turn On Outputs Idle Output Tri...

Page 119: ...gger No route the Timer resets allowing event detection to again occur immediately MANUAL Event detection occurs when the TRIG key is pressed TLINK Event detection occurs when an input trigger via the Trigger Link input line is received see Trigger link page 8 5 for more information STEST Event detection occurs when the start of test SOT line of the Digital I O port is pulsed low See Section 9 STE...

Page 120: ...of sweep points For linear staircase sweeps the number of points depends on the start stop and step current values For log staircase sweeps the number of points depends on the start and stop current values and the programmed number of points Counter The programmable counter is used to repeat operations within the Trigger Layer For example to repeat a sweep three times the trigger counter would be ...

Page 121: ...f the unit is in the Immediate trigger mode it will process readings continuously When a sweep is enabled the unit will perform one sweep per Trigger In Event One output trigger will be generated when the sweep is completed In order to use the RECALL mode the unit must be placed in the INIT CONTIN UOUS OFF mode See Configuring triggering page 8 7 Trigger link Input and output triggers are received...

Page 122: ...ations Output trigger specifications The Model 2520 can be programmed to output a trigger after various trigger model actions See Trigger model front panel operation page 8 2 The output trigger provides a TTL compatible output pulse that can be used to trigger other instruments The specifi cations for this trigger pulse are shown in Figure 8 4 A trigger link line can source 1mA and sink up to 50mA...

Page 123: ... automati cally be selected if the PULSE mode is selected or if a front panel sweep is initiated HALT Use to return the Model 2520 to the idle state HALT does not turn off the output The programmed source levels will still be available at the OUTPUT terminals The following actions will take the Model 2520 out of idle Turn the outputs off and then on again Reselect the arm or trigger event Exit fro...

Page 124: ...igital I O port is pulsed either high or low TRIGGER OUT Use to configure the output trigger LINE Select the Trigger Link line for the output trigger line 1 2 3 4 5 or 6 EVENTS Enable ON or disable OFF the arm layer output triggers TRIG LAYER DONE ON enables an output trigger on exiting the trigger layer Figure 8 5 Configure trigger menu tree CONFIG TRIG HALT TRIGGER IN COUNT LINE EVENTS IMMEDIATE...

Page 125: ...ns are available to provide synchronization between the Model 2520 and other instruments via the Trigger Link Idle and initiate The instrument is considered to be in the idle state when it is not operating within the trig ger layer While in the idle state the instrument cannot perform any measurements An ini tiate command is required to take the instrument out of idle The following commands perfor...

Page 126: ...ocess Repeat Trigger Event Detector Trig In Event Trigger Layer Note The following commands place the Model 2520 into idle DCL SDC ABORt RST SYSTem PREset and RCL TRIGger SOURce IMMediate BUS TIMer MANual TLINK NSTest PSTest BSTest No See Note INITiate NONE TRIGger TRIGger COUNt n INF SOURce1 PULSe WIDTh 10µsec SOURce1 PULSe DELay 1µsec Note Sweep performed only if enabled Filter count determines ...

Page 127: ...ately allowing operation to continue BUS Event detection occurs when a bus trigger GET or TRG is received TIMer Event detection occurs immediately on the initial pass through the trigger model Each subsequent detection is satisfied when the programmed timer interval elapses The timer resets to its initial state when the instrument goes into idle MANual Event detection occurs when the TRIG key is p...

Page 128: ... DSP processed for each pulse Filtering If the filter is enabled the instrument cycles through the delay pulse loop for the pro grammed filter count and averages the specified number of readings to yield a single set of filtered readings measurements Sweep points When a sweep is enabled the unit cycles through the complete delay pulse process including filtering if enabled for the programmed numbe...

Page 129: ...one measurement cycle when the INITiate command is sent After the measurement the Model 2520 returns to the idle state Operation summary The trigger model is designed to offer versatility for the various source and measure appli cations It allows you to specify input and output triggers for both single reading and sweep operation as follows When sweeps are disabled the unit will process one set of...

Page 130: ...nt 1 to 5000 TRIGger ILINe line Select trigger link input line 1 to 6 TRIGger OLINe line Select trigger link output line 1 to 6 TRIGger OUTPut event Enable disable output trigger TRIGger or NONE TRIGger SOURce source Select trigger input source IMMediate TIMer BUS TLINK PSTest NSTtest or BSTest TRIGger TIMer time Set trigger timer 0 to 99999 99s TRG Trigger Model 2520 if BUS source selected Table ...

Page 131: ...es on the Digital I O Port as well as the 5V line that can be used to power external logic circuits Interlocks Describes how to use to determine the status of the interlocks Pulse sync output Describes the pulse sync output pulse that can be used to synchronize external equipment to current source pulses ...

Page 132: ...ne Each open collector output can be set high 5V or low 0V Each output line can source up to 2mA or sink up to 500mA TRIGGER LINK PULSE SYNC OUT TESTHEAD CONN 1 LINE FUSE SLOWBLOW 1 6A 250V LINE RATING 100 240VAC 50 60Hz 140VA MAX TESTHEAD CONN 2 CAT I WARNING NO INTERNAL OPERATOR SERVICABLE PARTS SERVICE BY QUALIFIED PERSONNEL ONLY CAUTION FOR CONTINUED PROTECTION AGAINST FIRE HAZARD REPLACE FUSE...

Page 133: ...ort provides a 5V output that can be used to drive external logic cir cuitry Maximum current output for this line is 300mA This line is protected by a self resetting fuse Digital output configuration There are two basic methods to connect external components to the digital output lines sink operation and source operation Sink operation Figure 9 2 shows the basic output configuration for sink opera...

Page 134: ... output lines The Digital I O lines can be used to control external relays or indicator lights You can control these lines either from the front panel or via remote as covered below Front panel digital output control Set digital output line logic levels from the front panel as follows 1 Press the DIG OUT key 2 Using the EDIT keys set the digital output parameter to the desired decimal value Table ...

Page 135: ...REMOTE INTERLOCK connector is a DB 9 connector intended for such applications as a remote interlock switch while the KEY INTERLOCK connector is intended for connec tions for a security key switch NOTE Both interlocks must be enabled for operation Otherwise the source outputs will not turn on See Section 2 for detailed interlock connection information Table 9 1 Digital output line settings OUT 4 OU...

Page 136: ...re enabled and can be turned on If the lid of the test fixture opens Figure 9 4B the switch opens and the three source outputs are disabled and cannot be turned on Figure 9 4 Interlock operation Pin 9 Interlock Switch Closed Model 2520 Testhead Test Fixture A Model 2520 outputs can be turned on Interlock Switch Open Test Fixture B Model 2520 outputs cannot be turned on Remote Interlock Pin 1 Model...

Page 137: ...icator on the mainframe should be OFF 6 Press the OUTPUT ON OFF switch on the mainframe At this point the INTERLOCK STATUS indicator should be GREEN and the LASER POWER ON indicator should be BLUE on the testhead The OUTPUT ON OFF indicator on the mainframe should be BLUE 7 Turn the key in the key interlock to DISABLED At this point the INTERLOCK STATUS indicator should be BLUE and the LASER POWER...

Page 138: ...e sync waveform Figure 9 5 shows the pulse sync waveform which is a 5V pulse with 50Ω output imped ance The pulse timing and duration are approximately the same as those for the laser diode current source pulse however there is a certain amount of latency between the pulse sync and the laser diode current pulse Figure 9 5 Pulse sync output waveform High 5V Typical Low 0V Typical Latency Pulse Sync...

Page 139: ...ync out connections TRIGGER LINK PULSE SYNC OUT TESTHEAD CONN 1 LINE FUSE SLOWBLOW 1 6A 250V LINE RATING 100 240VAC 50 60Hz 140VA MAX TESTHEAD CONN 2 CAT I WARNING NO INTERNAL OPERATOR SERVICABLE PARTS SERVICE BY QUALIFIED PERSONNEL ONLY CAUTION FOR CONTINUED PROTECTION AGAINST FIRE HAZARD REPLACE FUSE WITH SAME TYPE AND RATING MADE IN U S A IEEE 488 CHANGE IEEE ADDRESS WITH FRONT PANEL MENU DIGIT...

Page 140: ...Covers GPIB bus standards bus connections and primary address selection General bus commands Describes general bus commands used for fundamen tal GPIB control Front panel GPIB operation Summarizes GPIB error messages status indica tors and using the LOCAL key Programming syntax Describes the basic programming syntax for both com mon and SCPI commands RS 232 interface operation Outlines use of the ...

Page 141: ...ned on the continuous init mode is turned on Otherwise the Model 2520 is placed into the Idle layer of the Trigger Model All user defined displays are disabled The display is re enabled if it was previously turned off The laser diode current source is placed in the FIXed mode Selecting an interface The Model 2520 supports two built in remote interfaces GPIB General Purpose Interface Bus RS 232 int...

Page 142: ...selected interface you must re enter the COMM menu GPIB operation This section contains information about GPIB standards bus connections and primary address selection GPIB standards The GPIB is the IEEE 488 instrumentation data bus with hardware and programming standards originally adopted by the IEEE Institute of Electrical and Electronic Engineers in 1975 The Model 2520 conforms to these standar...

Page 143: ...To allow many parallel connections to one instrument stack the connectors Two screws are located on each connector to ensure that connections remain secure Figure 10 2 shows a typical connecting scheme for a multi unit test system Figure 10 2 IEEE 488 multi unit test system connections To avoid possible mechanical damage stack no more than three connectors on any one unit Instrument Controller Ins...

Page 144: ... the controller Most controllers are equipped with an IEEE 488 style connector but a few may require a different type of connecting cable See your controller s instruction manual for information about properly connecting to the IEEE 488 bus NOTE You can only have 15 devices connected to an IEEE 488 bus including the con troller The maximum cable length is either 20 meters or two meters multiplied ...

Page 145: ... Press the COMM key 2 Select GPIB then press ENTER 3 Use the EDIT keys to set the primary address to the desired value then press ENTER 4 Select GPIB or 488 1 protocol then press ENTER See Appendix G for details 5 Press EXIT to return to normal display General bus commands General commands are those commands such as DCL that have the same general mean ing regardless of the instrument Table 10 1 li...

Page 146: ...N lights if the instrument was previously placed in one of these states Note that this command does not affect the status of the instrument Settings data and event registers are not changed To send the IFC command the controller need only set the IFC line true for a minimum of 100µs LLO local lockout Use the LLO command to prevent local operation of the instrument After the unit receives LLO all o...

Page 147: ...BUS NOTE With TRIG SOURce BUS selected and an INITiate command sent do not send any commands except GET DCL SDC IFC TRG and ABORt while per forming source and measure operations ARM annunciator on If you do erratic operation will occur SPE SPD serial polling Use the serial polling sequence to obtain the Model 2520 serial poll byte The serial poll byte contains important information about internal ...

Page 148: ...ace the unit in the talker idle state by sending a UNT Untalk command addressing it to listen or sending the IFC Interface Clear command LSTN This indicator is on when the Model 2520 is in the listener active state which is activated by addressing the instrument to listen with the correct MLA My Listen Address com mand LSTN is off when the unit is in the listener idle state Place the unit in the l...

Page 149: ...n the command word and the parameter is required Brackets 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 pro gram message For example INITiate IMMediate These brackets indicate that IMMediate is implied optional and does not have to be used Thus the above command can be sent in one of two ways INITiate...

Page 150: ...lse delay to 20µs SOURce1 PULSe DELay MAXimum Sets pulse delay to 100msec numlist Numlist Specify one or more numbers for a list Example STATus QUEue ENABle 110 222 Enable errors 110 through 222 NDN Non decimal numeric This parameter is used to send values in the bina ry octal or hexadecimal format The prefix designates the format type Bxx x B specifies the binary format xx x is the binary number ...

Page 151: ...e value SOURce1 PULSe DELay MAXimum Queries the largest allowable value Case sensitivity Common commands and SCPI commands are not case sensitive You can use upper or lower case and any case combination Examples RST rst DATA data SYSTem PRESet system preset NOTE Using all upper case will result in slightly faster command response times Long form and short form versions A SCPI command word can be s...

Page 152: ...enclosed in brackets are optional and need not be included in the program message NOTE For fastest response to commands always use short forms Program messages A program message is made up of one or more command words sent by the computer to the instrument Each common command is a three letter acronym preceded by an asterisk SCPI commands are categorized in the STATus subsystem and are used to exp...

Page 153: ...ture Since enab is also on the third level it can be typed in without repeating the entire path name Notice that the leading colon for enab is not included in the pro gram message If a colon were included the path pointer would reset to the root level and expect a root command Since enab is not a root command an error would occur Command path rules Each new program message must begin with the root...

Page 154: ... invalid command in a multiple command program message are executed Valid commands that follow an invalid command in a multiple command program message are ignored Response messages A response message is the message sent by the instrument to the computer in response to a query command program message Sending a response message After sending a query command the response message is placed in the Out...

Page 155: ...fore another program message can be sent to the Model 2520 RS 232 interface operation NOTE The programmable aspects of RS 232 operation baud rate data bits parity and terminator are configured from the COMMUNICATIONS SETUP menu accessed with the COMM key Sending and receiving data The RS 232 interface transfers data using 8 data bits 1 stop bit and no parity Make sure the device you connect to the...

Page 156: ...line feed LF Line feed LF CR Line feed and carriage return Flow control signal handshaking Signal handshaking between the controller and the instrument lets the two devices com municate with each other about readiness to receive data The Model 2520 does not sup port hardware handshaking flow control Software flow control is in the form of XON and XOFF characters and is enabled when XON XOFF is sel...

Page 157: ...h DB 9 connectors such as a Keithley Model 7009 5 Do not use a null modem cable The serial port uses the transmit TXD receive RXD and signal ground GND lines of the RS 232 standard Figure 10 4 shows the rear panel connector for the RS 232 interface and Table 10 2 shows the pinout for the connector If your computer uses a DB 25 connector for the RS 232 interface you will need a cable or adapter wit...

Page 158: ...smit data RXD receive data Not used GND signal ground Not used RTS ready to send CTS clear to send Not used Note CTS and RTS are tied together Pins 1 4 and 6 are tied together Table 10 3 PC serial port pinout Signal DB 9 pin number DB 25 pin number DCD data carrier detect RXD receive data TXD transmit data DTR data terminal ready GND signal ground DSR data set ready RTS request to send CTS clear t...

Page 159: ...rate to 9600 PRINT Set no flow control and CR as terminator Configure serial port parameters The following values are the default settings for the Model 2520 ComOpen COM2 9600 N 8 1 ASC CD0 CS0 DS0 LF OP0 RS TB8192 RB8192 OPEN ComOpen FOR RANDOM AS 1 Model 2520 setup commands PRINT 1 RST Reset instrument to default parame ters PRINT 1 SENS1 VOLT RANG 3 Set 3V measure range PRINT 1 SOUR1 CURR 0 1 S...

Page 160: ...ter in the status structure Status byte and service request SRQ Explains how to program the Status Byte to generate service requests SRQs Shows how to use the serial poll sequence to detect SRQs Status register sets Provides bit identification and command information for the four status register sets Standard Event Status Operation Event Status Mea surement Event Status and Questionable Event Stat...

Page 161: ...med by the user the RQS MSS bit will set to indicate that an SRQ has occurred Status register sets A typical status register set is made up of a condition register an event register and an event enable register A condition register is a read only register that constantly updates to reflect the present operating conditions of the instrument When an event occurs the appropriate event register bit se...

Page 162: ...DE EXE CME URQ PON 8 9 12 13 15 Register 8 9 12 13 15 Register Logical OR Always Zero Operation Complete Query Error Device Specific Error Execution Error Command Error User Request Power On OPC QYE DDE EXE CME URQ PON ESR ESE MSB MSB 15 Always Zero 15 Event Register 15 Event Enable Register Logical OR Condition Register RAV RAV RAV Reading Available 1 1 Cal Cal Calibration Summary 2 2 2 9 9 9 1 1...

Page 163: ...ription Ref To Reset Registers CLS STATus PRESet To Clear Error Queue CLS STATus QUEue CLEar Reset all bits of the following event registers to 0 Standard Event Register Operation Event Register Measurement Event Register Questionable Event Register Reset all bits of the following enable registers to 0 Operation Event Enable Register Measurement Event Enable Register Questionable Event Enable Regi...

Page 164: ...r octal The bit positions of the register indicate the binary parameter value For example if you wish to sets bits B4 B3 and B1 the binary value would be 11010 where B4 1 B3 1 B1 1 and all other bits are 0 When you use one of the other formats convert the binary number to its decimal hexadecimal or octal equivalent Binary 11010 Decimal 26 Hexadecimal 1A Octal 32 Note that Figure 11 2 includes the ...

Page 165: ...an be read by using the appropriate query com mand The following explains how to interpret the returned value response message The actual query commands are covered later in this section Table 11 3 through Table 11 7 The response message will be a value that indicates which bits in the register are set That value if not already binary will have to be converted to its binary equivalent For exam ple...

Page 166: ... for reading status registers name ASCii Decimal format HEXadecimal Hexadecimal format OCTal Octal format BINary Binary format ASCii ESB OSB ESB STB OSB SRE SRE OR B6 RQS B5 B77 B5 B6 Serial Poll Service Request Generation B7 MSS MAV Status Summary Message Read by Serial Poll Read by STB Status Byte Register Service Request Enable Register MAV B4 B4 QSB QSB B3 B3 EAV EAV B2 B2 B1 B1 MSB MSB B0 B0 ...

Page 167: ...B Set summary bit indicates that an enabled standard event has occurred Bit B6 Request Service RQS Master Summary Status MSS Set bit indi cates that an enabled summary bit of the Status Byte Register is set Bit B7 Operation Summary OSB Set summary bit indicates that an enabled operation event has occurred Depending on how it is used Bit B6 of the Status Byte Register is either the Request for Serv...

Page 168: ...Typically SRQs are managed by the serial poll sequence of the Model 2520 If an SRQ does not occur bit B6 RQS of the Status Byte Register will remain cleared and the pro gram will simply proceed normally after the serial poll is performed If an SRQ does occur bit B6 of the Status Byte Register will set and the program can branch to a service subroutine when the SRQ is detected by the serial poll Th...

Page 169: ... the Status Byte Register using the binary format which directly indicates which bits are set The command to select format FORMat SREGister is documented in Table 11 2 To determine the exact nature of the error you will have to read the Error Queue Refer to Queues page 11 19 Table 11 3 Status byte and service request enable register commands Command Description Default STB SRE NDN or NRf SRE Read ...

Page 170: ...et bit indicates that you attempted to read data from an empty Output Queue Bit B3 Device Dependent Error DDE Set bit indicates that an instrument operation did not execute properly due to some internal condition Bit B4 Execution Error EXE Set bit indicates that the Model 2520 detected an error while trying to execute a command Bit B5 Command Error CME Set bit indicates that a command error has oc...

Page 171: ...DE Device Dependent Error QYE Query Error OPC Operation Compete Logical AND OR Logical OR DDE B3 QYE B2 B1 OPC B0 EXE B4 CME B5 URQ B6 PON B7 B15 B8 Standard Event Status Enable Register OR To Event Summary Bit ESB of Status Byte Register Figure 11 3 ESE ESE Standard Event Status Register ESR DDE B3 QYE B2 B1 OPC B0 EXE B4 CME B5 URQ B6 PON B7 B15 B8 ...

Page 172: ...cur Bits B6 through B9 Not used Bit B10 Idle State Idle Set bit indicates the Model 2520 is in the idle state Bits B11 through B15 Not used Figure 11 5 Operation event status Cal B0 Trig B5 B9 B6 Idle B10 B15 B11 Operation Condition Register Operation Event Register Operation Event Enable Register OR To Operation Summary Bit OSB of Status Byte Register Figure 11 3 Stat oper cond Cal B0 Trig B5 B9 ...

Page 173: ... is in an overflow condition Bit B4 MSR3 Overflow M3O Set bit indicates that the photodiode detector 2 current measurement is in an overflow condition Bit B5 Not used Bit B6 Reading Available RAV Set bit indicates that a reading has been pro cessed and is available Bit B7 Sweep Aborted SWA Set bit indicates that the sweep was aborted before being completed Bit B8 Sweep Done SWD Set bit indicates a...

Page 174: ...d stat meas stat meas enab NRF stat meas enab B9 SWD B8 SWA B7 RAV B6 B5 M3O B4 M20 B3 M1O B2 INT B1 B0 B10 B11 OT B12 B13 S1C B14 B15 B9 SWD B8 SWA B7 RAV B6 B5 M3O B4 M20 B3 M1O B2 INT B1 B0 B10 B11 OT B12 B13 S1C B14 B15 B9 SWD B8 SWA B7 RAV B6 B5 M3O B4 M20 B3 M1O B2 INT B1 B0 S1C Laser Source in Compliance SWD Sweep Done SWA Sweep Aborted RAV Reading Available M3O MRS 1 Overflow M2O MSR 2 Ove...

Page 175: ...he instrument Bits B9 through B13 Not used Bit B14 Command Warning Warn Set bit indicates that a Signal Oriented Measurement Command parameter has been ignored Bit B15 Not used Figure 11 7 Questionable event status Questionable Event Enable Register OR To QSB of Status Byte Register Figure 11 3 Warn Command Warning B7 B0 CAL B8 B13 B9 B15 Warn B14 Questionable Condition Register Questionable Event...

Page 176: ...priate event register bit sets to 1 The bit remains latched to 1 until the register is reset Reading an event register clears the bits of that register CLS resets all four event registers The commands to read the event registers are listed in Table 11 6 For details on reading registers see Reading registers page 11 6 Table 11 5 Condition register commands Command Description STATus OPERation CONDi...

Page 177: ...ameter value with the appropriate enable command i e STATus OPERation ENABle 0 Table 11 7 Event enable registers commands Command Description Default ESE NDN or NRf ESE STATus OPERation ENABle NDN or NRf ENABle MEASurement ENABle NDN or NRf ENABle QUEStionable ENABle NDN or NRf ENABle Program Standard Event Enable Register See Parameters Read Standard Event Enable Register STATus Subsystem Operati...

Page 178: ...put queue The output queue holds data that pertains to the normal operation of the instrument For example when a query command is sent the response message is placed in the Output Queue When data is placed in the Output Queue the Message Available MAV bit in the Status Byte Register sets A data message is cleared from the Output Queue when it is read The Output Queue is considered cleared when it ...

Page 179: ...eue are preceded by a code number Negative numbers are used for SCPI defined messages and positive numbers are used for Keithley defined messages The messages are listed in Appendix B As shown in Table 11 7 there are com mands to read the entire message code and message or the code only On power up all error messages are enabled and will go into the Error Queue as they occur Status messages are no...

Page 180: ...or Error Queue Read the enabled messages Specify messages not to be placed in queue Read the disabled messages Clear messages from Error Queue SYSTem Subsystem Read Error Queue Read and clear oldest error status code and message Read and clear all errors status code and message Read the number of messages in queue Code numbers only Read and clear oldest error status code only Read and clear all er...

Page 181: ...summary Lists the IEEE 488 2 common commands used by the Model 2520 Command reference Provides a detailed reference for all common commands except for those associated with the status structure which are discussed in Section 11 ...

Page 182: ...us byte query Trigger command Self test query Wait to continue command Clears all event registers and Error Queue 1 Program the Standard Event Enable Register 1 Read the Standard Event Enable Register 1 Read and clear the Standard Event Enable Register 1 Returns the manufacturer model number serial number and firmware revision levels of the unit Set the Operation Complete bit in the Standard Event...

Page 183: ...ad pulser board revision level OPC operation complete Sets OPC bit OPC operation complete query Places a 1 in output queue When OPC is sent the OPC bit in the Standard Event Register will set after all pending command operations are complete When OPC is sent an ASCII 1 is placed in the Output Queue after all pending command operations are complete Typically either one of these commands is sent aft...

Page 184: ...emory location 1 2 Memory location 2 3 Memory location 3 4 Memory location 4 Use the SAV command to save the present instrument setup configuration in memory for later recall Any control affected by RST can be saved by the SAV command The RCL command is used to restore the instrument to the saved setup configuration Five setup configurations can be saved and recalled The Model 2520 ships from the ...

Page 185: ...trigger to the Model 2520 It has the same effect as a group execute trigger GET Use the TRG command as an event to control operation The Model 2520 reacts to this trigger if BUS is the programmed arm control source using the TRIG SOUR BUS com mand NOTE Details on triggering are covered in Section 8 TRG programming example The command sequence in Table 12 4 configures the Model 2520 to be controlle...

Page 186: ...s not need to be used Two types of device commands exist Sequential commands A command whose operations are allowed to finish before the next command is executed Overlapped commands A command that allows the execution of subsequent commands while device operations of the Overlapped command are still in progress The WAI command is used to suspend the execution of subsequent commands until the devic...

Page 187: ...asurementCommands Command summary Summarizes those commands used to acquire readings Acquiring readings Describes commands to acquire post processed readings both trigger and acquire readings and to perform a single measurement ...

Page 188: ...w readings this command continues to return the old readings For example assume that the Model 2520 performed 20 source and measure operations The FETCh command will request the readings for those 20 source and measure operations If FETCh is sent while performing source and measure operations ARM annunciator on it will not be executed until the Model 2520 goes back into idle NOTE The FETCh command...

Page 189: ...f readings How ever if the unit is in the sweep mode this command will trigger the sweep and then acquire all sweep data points When this command is sent the following commands execute in the order they are presented INITiate FETCh The INITiate command starts operation by taking the instrument out of idle NOTE READ is illegal when the TRIG SOUR BUS command is in effect See Section 8 Triggering for...

Page 190: ...14 SCPICommandReference Reference tables Summarizes each SCPI command subsystem SCPI subsystems Provides detailed information on all commands in each SCPI subsystem ...

Page 191: ...t Parameter Listed parameters are both the RST and SYSTem PRESet defaults unless noted otherwise Parameter notes are located at the end of each table SCPI A checkmark indicates that the command and its parameters are SCPI con firmed An unmarked command indicates that it is a SCPI command but does not conform to the SCPI standard set of commands It is not a recognized command by the SCPI con sortiu...

Page 192: ...99999e20 to 9 99999e20 Query B parameter Set M parameter 9 99999e20 to 9 99999e20 Query M parameter Set MX B units 1 character ASCII string Query M parameter Enable or disable CALC1 math Query state of math RES 0 1 X OFF CALCulate2 DATA LATest DATA KMATh MBFactor n MBFactor MMFactor n MMFactor MUNits string MUNits STATe b STATe Path to configure and control detector 1 math Path to CALC2 data Retur...

Page 193: ... result Read result of math generated by INIT Configure MX B parameters Set B parameter 9 99999e20 to 9 99999e20 Query B parameter Set M parameter 9 99999e20 to 9 99999e20 Query M parameter Set MX B units 1 character ASCII string Query M parameter Enable or disable CALC3 math Query state of math Path to control delta detector 1 current detector 2 current Read math result generated by INIT Return o...

Page 194: ...Query data on top portion of display Path to locate message to bottom display line Control user test message Define ASCII message a up to 32 characters Query text message Enable or disable message mode Query text message state Query data on bottom portion of display Note 1 Note 2 Note 3 Note 2 Note 3 Notes 1 RST and SYSTem PRESet has no effect on the display circuitry Pressing LOCAL or cycling pow...

Page 195: ...STATus ASC ASC Note VOLT1 CURR2 CURR3 CALCulate item list CALCulate TRACe item list TRACe ELEMents SOURce4 name SOURce4 Specify CALCulate data elements CALCulate TIME and STATus Query CALCulate data elements Specify TRACe data elements VOLTage 1 CURRent2 CURRent3 and TIME Query TRACe data elements Query FETCh and READ data format elements Specify SOURce4 data format ASCii HEXadecimal OCTal or BIN ...

Page 196: ...F SENSe2 CURRent DC RANGe UPPer n UPPer POLarity name POLarity AVERage COUNt n COUNt STATe b STATe SWEep CABort LEVel n LEVel STATe b STATe DATA LATest Sense 2 subsystem to control detector 1 current measurement Path to configure current Configure measurement range Select range by specifying the expected current reading 0 to 0 105 Ranges 0 01 0 02 0 05 0 1 Query range Select polarity Name POSitive...

Page 197: ...ge Select polarity Name POSitive or NEGative Query polarity Path to configure digital filter Specify filter count 1 to 100 Query filter count Enable or disable digital filter Query state of digital filter Path to sweep abort commands Set detector 2 current level for sweep abort 0 to 0 105 Query detector 2 sweep abort current threshold Enable or disable detector 2 sweep abort function Query state o...

Page 198: ...polarity FIX 0 5 0 0 POS STARt n STARt STOP n STOP STEP n STEP SPAN n SPAN CENTer n CENTer FUNCtion SHAPe name SHAPe PULSe DELay n DELay WIDTh n WIDTh TRANsition STATe b STATe Specify start level for I sweep 0 to 5 0 Query start level for current sweep Specify stop level for I sweep 0 to 5 0 Query stop level for current sweep Specify step value for I sweep 0 to 5 0 Query step value for current swe...

Page 199: ...Add up to 100 source values to end of list Query number of source values in list Query all points in source list Create list of pulse width values 500e 9 to 5e 3 3 Add up to 100 pulse width values to end of list Query number of pulse width values in list Query all points in pulse width list Create list of pulse delay values 20e 6 to 0 5 3 Add up to 100 pulse delay values to end of list Query numbe...

Page 200: ...el Path to control detector 2 voltage bias source Set source level in volts Set specified voltage level immediately Specify voltage level 20 to 20 Query voltage level 0 0 SOURce4 BSIZe n BSIZe TTL LEVel NRf NDN LEVel Path to control digital output lines Set Digital I O bit size 4 or 16 1 Query Digital I O bit size Specify digital output pattern 0 to 15 2 Query pattern on digital output port No eff...

Page 201: ...th to access error queue Read the most recent error message Specify error and status messages for error queue Read the enabled messages Specify messages not to be placed in error queue Read the disabled messages Clears all messages from error queue Note 1 Note 2 Note 3 Note 2 Note 3 Note 2 Note 3 Note 4 Note 5 Note 5 Notes 1 Commands in this subsystem are not affected by RST and SYSTem PREset The ...

Page 202: ...ode numbers only Return and clear oldest error code only Return and clear all errors codes only Clears messages from error queue Simulate key press 1 to 31 Query the last pressed key Timestamp Reset timestamp to zero seconds Take unit out of remote and cancel local lockout RS 232 Put unit in remote RS 232 Enable local lockout RS 232 1Clearing Error Queue Power up and CLS clears the error queue RST...

Page 203: ...ption Default parameter SCPI INITiate IMMediate ABORt TRIGger SEQuence 1 LAYer 1 COUNt n COUNt SOURce name SOURce TIMer n TIMer TCONfigure ASYNchronous ILINe n ILINe OLINe n OLINe OUTPut name OUTPut Initiate source and measure cycle s Reset trigger system Goes to idle state Path to program Trigger Layer Specify trigger count 1 to 5000 or INFinite Query trigger count INFinite 9 9e37 Specify control...

Page 204: ...r n Set laser diode B offset value CALCulate2 KMATh MBFactor n Set detector 1 B offset value CALCulate3 KMATh MBFactor n Set detector 2 B offset value Parameters n 9 99999e20 to Specify B offset value for MX B 9 99999e20 MINimum 9 99999e20 MAXimum 9 99999e20 DEFault 0 Query MBFactor Query B offset value for MX B Description These commands program the B offset value for the MX B math function Use C...

Page 205: ...STATe b CALCulate 1 STATe b Control laser diode math function CALCulate2 STATe b Control detector 1 math function CALCulate3 STATe b Control detector 2 math function CALCulate4 STATe b Control delta detector 1 detector 2 math function Parameters b 0 or OFF Disable CALC1to CALC4 math function Parameters 1 or ON Enable CALC1 to CALC4 math function Query STATe Query state on or off of CALC1 to CALC4 ...

Page 206: ...e4 DATA LATest Read latest CALC4 result Description These commands work exactly like CALC1 DATA CALC2 DATA CALC3 DATA and CALC4 DATA except that they return only the latest CALC1 CALC2 CALC3 or CALC4 result DISPlay subsystem The display subsystem controls the display of the Model 2520 and is summarized in Table 14 2 Control display ENABle b DISPlay ENABle b Control display circuitry Parameters b 0...

Page 207: ...ad what is currently being dis played on the top and bottom displays After sending one of these com mands and addressing the Model 2520 to talk the displayed data message or reading will be sent to the computer Define TEXT messages DATA a DISPlay WINDow 1 TEXT DATA a Define message top display DISPlay WINDow2 TEXT DATA a Define message bottom display Parameters a ASCII characters for message Types...

Page 208: ...om the display GPIB Operation A user defined text message remains displayed only as long as the instrument is in remote Taking the instrument out of remote by pressing the LOCAL key or sending LOCAL 26 cancels the message and disables the text message mode RS 232 Operation A user defined test message can be cancelled by sending the SYSTem LOCal command or pressing the LOCAL key FORMat subsystem Th...

Page 209: ...date the conversion Figure 14 1 shows an example ASCII string that includes current voltage time and status data elements Data elements not specified by the ELEMents command are simply not included in the string See ELEMents item list page 14 22 Figure 14 1 ASCII data format IEEE 754 single precision format REAL 32 or SREal will select the binary IEEE 754 single precision data format Figure 14 2 s...

Page 210: ... set your computer program to terminate on EOI only The number of bytes to be transferred can be calculated as follows Bytes 2 Rdgs 4 1 where 2 is the number of bytes for the header 0 Rdgs is the product of the number of selected data elements arm count and trigger count 4 is the number of bytes for each reading is the byte for the terminator For example assume the Model 2520 is configured to perf...

Page 211: ...the elements to be included in the data string in response to the following queries FETCh READ MEASure You can specify from one to all eight elements Each element in the list must be separated by a comma These elements shown in Figure 14 1 are explained as follows NOTE An overflow reading reads as 9 9E37 CURRent 1 This element provides the laser diode current source value CURRent2 This element pro...

Page 212: ...termine the state of each bit in the word For example if the status value is 17 the binary equivalent is 0000000000010001 Bits 0 and 4 are set The significance of each status bit is explained as follows Bit 0 OFLO1 Set to 1 if the laser diode voltage measurement was made while in over flow Cleared to 0 otherwise Bit 1 OFLO2 Set to 1 if the detector 1 current measurement was made while in over flow...

Page 213: ...Mat ELEMents TRACe item list Specify TRACe data string elements Parameters item list VOLTage 1 Includes laser diode voltage CURRent2 Includes detector 1 current reading CURRent3 Includes detector 2 current reading TIME Includes timestamp NOTE Each item in the list must be separated by a comma i e VOLT1 CURR2 TIME Query TRACe Query TRACe data string elements Description This command is used to spec...

Page 214: ...e measurement data SOURce4 name FORMat SOURce4 name Set SOUR4 TTL response format Parameters name ASCii ASCII format HEXadecimal Hexadecimal format OCTal Octal format BINary Binary format Query SOURce4 Query response format Description This command controls the response format for the SOUR4 TTL query in a manner similar to formats set by the FORM SREG command See SOURce subsystem page 14 32 for de...

Page 215: ...s name ASCii Decimal format Hexadecimal Hexadecimal format OCTal Octal format BINary Binary format Query SREGister Query format for reading status registers Description Query commands are used to read the contents of the status event regis ters This command is used to set the response message format for those query commands When a status register is queried the response message is a value that ind...

Page 216: ... to determine if the two interlocks have been tripped The tripped condition 1 means that the sources can be turned on interlock line at logic low level A 0 will be returned if the sources cannot be turned on interlock line at logic high level See Section 2 and Section 9 for details on the interlocks SENSe subsystem The SENSe subsystem is used to configure and control the measurement channels of th...

Page 217: ...ding that will accommodate that reading For example if you expect a reading of approximately 7V then simply let n 7 in order to select the 10V range You can also use the UP and DOWN parameters to select range Each time UP or DOWN is sent the next higher or lower measurement range is selected When on the maximum range sending UP is a No Op no operation When on the lowest range sending DOWN is a NO ...

Page 218: ...t polarity SENSe2 CURRent POLarity name Set detector 1 measurement polarity SENSe3 CURRent POLarity name Set detector 2 measurement polarity Parameters name POSitive Positive polarity NEGative Negative polarity Query POLarity Query measurement polarity Description These commands are used to select the measurement polarity for laser diode voltage measurements and detector current measurements POSit...

Page 219: ...ion 6 Filter Filter commands are global and affect all three measurement functions simultaneously COUNt n SENSe 1 AVERage COUNt n Set average filter count SENSe2 AVERage COUNt n Set average filter count SENSe3 AVERage COUNt n Set average filter count Parameters n 1 to 100 Specify average filter count DEFault 10 MINimum 1 MAXimum 100 Query COUNt Query filter count COUNt DEFault Query the RST defaul...

Page 220: ...05 MINimum 0 MAXimum 0 105 Query CABort LEVel Query sweep abort current threshold Description These commands provide means to set a maximum detector current for detector 1 or detector 2 that will cause a sweep to be aborted if the corresponding detector current threshold is reached Sweep abort must be enabled with the STATe command see below The Sweep Aborted bit Bit 7 in the Measurement Event Reg...

Page 221: ...d turns off all three source outputs Select sourcing mode MODE name SOURce 1 CURRent MODE name Select laser diode sourcing mode Parameters name FIXed Select fixed sourcing mode LIST Select list sourcing mode SWEep Select sweep sourcing mode Query MODE Query sourcing mode Description This command is used to select the sourcing mode for the laser diode current source The three modes are explained as...

Page 222: ...nd low amplitudes are set with the SOUR1 CURR AMPL and SOUR1 CURR LOW commands covered in Set amplitudes page 14 47 The pulse width and delay are set with the SOUR1 PULS WIDT and SOUR1 PULS DEL commands see Set pulse times page 14 36 Select source range RANGe n SOURce 1 CURRent RANGe n Select range for laser diode current source Parameters n 0 to 5 0 Specify source level amps DEFault 500mA range M...

Page 223: ...mmed source amplitude CURRent DEFault Query RST default amplitude CURRent MINimum Query lowest allowable amplitude CURRent MAXimum Query highest allowable amplitude Description This command is used to immediately update the amplitude of a fixed source for both DC and pulse functions with the pulse function the amplitude is the high pulse level This command is not valid if the list or sweep mode is...

Page 224: ...imit PROTection LEVel NRf SOURce 1 VOLTage PROTection LEVel NRf Set voltage compliance limit Parameters NRf 3 to 10 5 Set voltage compliance limit Query PROTection Query programmed voltage limit Description This command is used to the set the voltage protection limit which clamps the current source output voltage at the programmed limit See Section 5 Current source operating boundaries for more in...

Page 225: ...seconds MINimum 500e 9 seconds MAXimum 5e 3 seconds DEFault 10e 6 seconds Query WIDTh Query pulse width WIDTh DEFault Query RST default pulse width WIDTh MINimum Query lowest allowable pulse width WIDTh MAXimum Query highest allowable pulse width Description This command is used to set the current pulse width in the pulse func tion It sets the pulse width in the fixed and sweep modes but it does n...

Page 226: ...ng Query scale for sweep Description This command is used to select the scale for the sweep With LINear selected the source and measure points in the sweep will be performed on a linear scale With LOGarithmic selected the source and measure points will be performed on a logarithmic scale STARt n STOP n SOURce 1 CURRent STARt n Specify start current level SOURce 1 CURRent STOP n Specify stop curren...

Page 227: ...URce 1 CURRent SPAN n Specify span of sweep Parameters n 0 to 5 0 Set SPAN source level amps 0 to 5 0 Set CENT source level amps DEFault 0A MINimum 0A SPAN 0A CENT MAXimum 5 0A SPAN 5 0A CENT Query CENTer Query center point for sweep CENTer DEFault Query RST default level CENTer MINimum Query lowest allowable level CENTER MAXimum Query highest allowable level SPAN Query span for sweep SPAN DEFault...

Page 228: ...the start level to the stop level A measurement is performed at each source step including the start and stop levels NOTE This command cannot be used for a logarithmic sweep Use the POINts com mand to set the source and measure points for a log sweep To avoid a setting conflicts error make sure the step size is greater than the start value and less than the stop value The number of source and meas...

Page 229: ...that the start and stop levels are source and measure points Step size for a linear sweep can be calculated as follows Step Size Stop Start Points 1 Step Size Span Points 1 Step size for a logarithmic sweep can be calculated as follows An alternate way to set the source and measure points in a sweep is to specify the step size using the STEP command Note that the POINts and STEP commands are coupl...

Page 230: ...e instrument will sequentially source each current pulse value in the list A set of measurements are performed at each current pulse level The pulse width and delay are set with the WIDTh and DELay commands see below The pulse low level is set with the LOW command see Set amplitudes page 14 34 The following command shows the proper format for defining a list using source values of 1A 2A and 5A SOU...

Page 231: ...oint in the current and delay lists The following command shows the proper format for defining a list using pulse width values of 10µs 30µs and 60µs SOURce 1 LIST WIDTh 10e 6 30e 6 60e 6 NOTE If the width list is shorter than the current list the last width value will be used for all subsequent current list points If the width is not programmed a default value of 500ns will be used but the query w...

Page 232: ...µs 400µs and 500µs SOURce 1 LIST DELay 200e 6 400e 6 500e 6 NOTE If the pulse delay list is shorter than the current list the last pulse delay value will be used for all subsequent current list points If delay is not programmed a default value of 1 5ms will be used but the query will return 0 APPend NRf list SOURce 1 LIST DELay APPend NRf list Add value s to pulse delay list Parameters NRf list NR...

Page 233: ...0 SOUR1 CURR MODE SWE OUTP1 ON INIT List sweep List sweep with 100mA 200mA 300mA 400mA and 500mA current pulses pulse widths of 10µs 20µs 40µs 60µs and 70µs pulse delays of 100ms 150ms 200ms 250ms and 300ms RST SOUR1 LIST CURR 100e 3 200e 3 300e 3 400e 3 500e 3 SOUR1 LIST WIDT 10e 6 20e 6 40e 6 60e 6 70e 6 SOUR1 LIST DEL 100e 3 150e 3 200e 3 250e 3 300e 3 SOUR1 LIST CURR POIN returns 5 SOUR1 LIST ...

Page 234: ...0mA to 100mA in 20 points RST SOUR1 SWE SPAC LOG SOUR1 CURR STAR 10e 3 SOUR1 CURR STOP 100e 3 SOUR1 SWE POIN 20 SOUR1 CURR MODE SWE OUTP1 ON INIT To determine the current source values that will be generated Start 10 Log10 Start 1 Stop 100 Log10 Stop 2 LogStep Log10 Start Log10 Stop SWE POIN 1 2 1 20 1 1 19 0 105263 ...

Page 235: ...1052632 12 742751 4 1 1578948 14 384501 5 1 2105263 16 237767 6 1 2631579 18 329807 7 13157895 20 691382 8 1 3684211 23 357217 9 1 4210527 26 366513 10 1 4736842 29 763514 11 1 5263158 33 598184 12 1 5789474 37 926905 13 1 6315790 42 813329 14 1 6842105 48 329299 15 1 7368421 54 555947 16 1 7894737 61 584823 17 1 8421053 69 519286 18 1 8947369 78 476007 19 1 9473684 88 586675 20 2 0000000 100 0000...

Page 236: ...nds are used to immediately update the amplitude of the detector 1 and detector 2 voltage bias sources if the outputs are on If the outputs are off when either of these commands is sent the source value will be updated to the most recently programmed value when the outputs are turned on Note that the maximum output current for both voltage sources is 100mA SOURce4 The following commands are used t...

Page 237: ...Rce4 BSIZe NRf Set Digital I O bit size Parameters NRf 4 Set 4 bit size 16 Set 16 bit size 2499 DIGIO option Query BSIZe Query Digital I O port bit size Description This command sets the Digital I O bit size to 4 or 16 The 16 bit size is available only with the 2499 DIGIO option connected to the Digital I O port NOTE This command is not affected by RST SYSTem PRESet or RCL OUT 4 OUT 3 OUT 2 OUT 1 ...

Page 238: ...and addressing the Model 2520 to talk a value is sent to the computer This value indicates which bits in the appropriate register are set Program event enable registers ENABle NDN or NRf STATus MEASurement ENABle NDN or NRf Program Measurement Event Enable Register STATus QUEStionable ENABle NDN or NRf Program Questionable Event Enable Register STATus OPERation ENABle NDN or NRf Program Operation ...

Page 239: ...g SCPI event registers are cleared to zero 0 1 Operation Event Enable Register 2 Event Enable Register 3 Measurement Event Enable Register NOTE The Standard Event Register is not affected by this command Error queue NEXT STATus QUEue NEXT Read Error Queue Description As error and status messages occur they are placed into the Error Queue This query command is used to read those messages See Append...

Page 240: ...ssages for Error Queue Parameters list numlist where numlist is a specified list of messages that you wish to disable for the Error Queue Query DISable Query list of disabled messages Description On power up all error messages are enabled and will go into the Error Queue as they occur Status messages are not enabled and will not go into the queue This command is used to specify which messages you ...

Page 241: ... through Table 14 10 With the SAV0 4 parameters specified the instrument powers on to the setup that is saved in the specified location using the SAV command Error queue NOTE See Section 11 for details on the error queue NEXT SYSTem ERRor NEXT Read oldest error code and message Description As error and status messages occur they are placed in the Error Queue The Error Queue is a first in first out...

Page 242: ...s not returned The error is cleared from the queue CODE ALL SYSTem ERRor CODE ALL Read all errors codes only Description This query command is identical to the ALL command except only the codes are returned The actual messages are not returned All errors are cleared from the queue CLEar SYSTem CLEar Clear Error Queue Description This action command is used to clear the Error Queue of messages Simu...

Page 243: ...ssing the LASER VL key syst key 15 The parameter listing above provides the key press code in numeric order The queue for the KEY query command can only hold one key press When KEY is sent over the bus and the Model 2520 is addressed to talk the key press code number for the last key pressed either physi cally or with KEY is sent to the computer The key press code number for the last key pressed e...

Page 244: ...mmand is used to place the Model 2520 in the remote state in a manner similar to the GPIB REN command In remote the front panel keys will be locked out if local lockout is asserted See RWLock RWLock SYSTem RWLock Disable or enable front panel keys Description This command is used to enable local lockout in a manner similar to the GPIB LLO command See Section 10 When enabled the front panel keys ex...

Page 245: ... TRACe features are available over front panel TRAC DATA And TRAC DATA VAL will return errors unless SOUR1 MODE is FIXed TRIG ger COUNT is 1 and a reading has been triggered Read sample buffer DATA TRACe DATA Read raw samples from buffer Description This command returns the raw sample data taken during the latest trig gered reading The number of samples is specified by TRAC DATA POINts The sample ...

Page 246: ... example if the pulse width is 10µs the number of points will default to 100 in DC mode or 105 in the pulse mode Trigger subsystem The Trigger subsystem is made up of a series of commands and subsystems to configure the Trigger Model These commands and subsystems are summarized in Table 14 10 NOTE See Section 8 for more details on triggering and the trigger model Initiate source measure cycle INIT...

Page 247: ...ueries RST default count COUNt MINimum Queries lowest allowable count COUNt MAXimum Queries largest allowable count Description This command is used to specify how many times the unit cycles through the trigger layer For example if the trigger count is set to 2 the unit will cycle through the trigger layer twice TRIGger COUNt INFinite can be used for repetitive source waveforms or for long tests w...

Page 248: ... BUS selected the event occurs when a GET or TRG command is sent over the bus With NSTest selected the event occurs when the SOT start of test low pulse is received via the Digital I O port SOT line With PSTest selected the event occurs when SOT start of test high pulse is received via the Digital I O port SOT line With BSTest selected the event occurs when SOT start of test high or low pulse is r...

Page 249: ...Line 5 6 Line 6 Query OLINe Query output trigger line Description This command is used to select output lines for the Trigger Link For normal operation Trigger Link input and output see ILINe NRf should not share the same line OUTPut name TRIGger SEQuence 1 TCONfigure OUTPut name Enable disable trigger output event Parameters name TRIGger Trigger on exiting trigger layer NONE Disable trigger layer...

Page 250: ...A Specifications ...

Page 251: ...rdg current 1 2 RMS NOISE typical 3 10 00 mA 0 7 µA 10 Ω 0 3 20 µA 90 nA 20 00 mA 1 4 µA 6 Ω 0 3 65 µA 180 nA 50 00 mA 3 4 µA 3 Ω 0 3 90 µA 420 nA 100 00 mA 6 8 µA 2 5 Ω 0 3 175 µA 840 nA TEMPERATURE COEFFICIENT 0 18 C 28 50 C 0 15 x accuracy specification C INPUT PROTECTION The input is protected against shorting to the associated channel s internal bias supply The input is protected for shorts t...

Page 252: ...onverter has 14 bit resolution The useful resolution is improved by reading averaging The useful resolution is Setting Filter Averaging 100ns 400ns ns Width Pulse 1 2 Range Resolution Useful 14 15 Excluding total programmed Pulse ON time Pulse OFF time 16 Front panel off calc off filter off duty cycle 10 binary communications 17 Returning 1 voltage and 2 current measurements for each source point ...

Page 253: ... Accuracy of reading offset 0 3 5V 8mV 15mV 8mV 23mV Thus the actual reading range is 5V 23mV or from to 4 977V to 5 023V Source accuracy Source accuracy is calculated similarly except that source specifications are used to calcu late source accuracy as follows Accuracy of setting offset As an example of how to calculate the actual source output limits assume that you are sourcing 100mA DC on the ...

Page 254: ...B StatusandErrorMessages ...

Page 255: ...ers are used for Keithley defined messages Note that error and status conditions will also set specific bits in various status registers as sum marized in Table B 1 Section 11 has detailed information on registers and queues Briefly you can use the fol lowing queries to obtain error and status information SYST ERR reads Error Queue ESR reads Standard Event Status Register STAT OPER reads Operation...

Page 256: ...nning Illegal program name Cannot create program Expression error Hardware missing Data corrupt or stale EE EE EE EE EE EE EE EE EE EE Standard Event Standard Event Standard Event Standard Event Standard Event Standard Event Standard Event Standard Event Standard Event Standard Event 3 3 3 4 4 4 4 4 4 4 225 224 223 222 221 220 Out of memory Illegal parameter value Too much data Parameter data out ...

Page 257: ...data not allowed Too many digits EE EE EE EE EE Standard Event Standard Event Standard Event Standard Event Standard Event 5 5 5 5 5 123 121 120 114 113 Exponent too large Invalid character in number Numeric data error Header suffix out of range Undefined header EE EE EE EE EE Standard Event Standard Event Standard Event Standard Event Standard Event 5 5 5 5 5 112 111 110 109 108 Program mnemonic ...

Page 258: ...trigger layer Entering idle layer SE SE SE Operation Event Operation Event Operation Event 0 5 10 408 414 Questionable events Questionable Calibration Command Warning SE SE Questionable Event Questionable Event 8 14 500 501 502 503 504 505 506 507 508 509 510 Calibration errors Date of calibration not set Next date of calibration not set Calibration data invalid DAC calibration overflow DAC calibr...

Page 259: ...rd Event Standard Event Standard Event Standard Event Standard Event Standard Event Standard Event 3 3 3 3 3 3 3 3 3 802 803 810 830 900 Additional command execution errors OUTPUT blocked by interlock Not permitted with OUTPUT off OUTPUT blocked by over temp Invalid with INF TRIG COUNT Internal System Error EE EE EE EE EE Standard Event Standard Event Standard Event Standard Event Standard Event 4...

Page 260: ... between command and parameter SENS2 CURR RANG 10e 3 Correct Improper short or long form Check the command list in Section 14 for the correct command name Blanks spaces within the command name For example SYST ERR Incorrect space between SYST and ERR SYST ERR Correct 410 Query INTERRUPTED This error occurs when you have sent a valid query to the instrument and then send it another command or query...

Page 261: ...uery and still get this error make sure that the instrument is processing the query without error For example sending an ill formed query that generates an error 113 Undefined header and then addressing the instrument to talk will generate an error 420 Query UNTERMI NATED as well Valid query following an invalid command This situation can occur when you send multiple commands or queries program me...

Page 262: ...C DataFlow ...

Page 263: ...adings from the DSP For the fixed mode of operation the number of readings is equal to the trigger count For sweep or list mode operation the reading buffer stores all sweep data with the number of read ings determined both by sweep parameters and the trigger count The FETCh READ and MEASure queries access data from the reading buffer see below If CALC4 Enabled CALC4 DATA Bypass if CALC1 Disabled ...

Page 264: ...r The number of readings per sweep depends on programmed sweep parameters The data that is output by the read commands FETCh and READ depend on which data elements are selected With all elements selected available data includes both voltage and current measurements source values as well as the timestamp and status information See Section 14 FORMat ELEMents SCPI Command Reference for details After ...

Page 265: ...2 readings from A D detector 1 readings and then determines the pulse value or DC average over the pulse width from this new set of delta values TRACe DATA and TRACe DATA VALue All normal readings returned by FETCh READ MEASure and CALCulateX DATA are derived from samples acquired by a 14 bit A D converter that samples at 10MHz rate An internal DSP section interprets the A D samples over the pulse...

Page 266: ...D IEEE 488BusOverview ...

Page 267: ... a listener This handshake sequence helps ensure the credi bility of the information transfer The basic handshake sequence between an active con troller talker and a listener is as follows 1 The listener indicates that it is ready to listen 2 The talker places the byte of data on the bus and indicates that the data is available to the listener 3 The listener aware that the data is available accept...

Page 268: ...d These talk and listen commands are derived from an instrument s primary address The primary address may have any value between 0 and 30 and is generally set by rear panel DIP switches or programmed from the front panel of the instrument The actual lis ten address value sent out over the bus is obtained by ORing the primary address with H20 For example if the primary address is decimal 26 H1A the...

Page 269: ...le to Talk Listen and Control Computer Device 2 Able to Talk and Listen 2520 Device 3 Only Able to Listen Printer Device 4 Only Able to Talk DAV NRFD NDAC IFC ATN SRQ REN EOI Data Bus Data Byte Transfer Control General Interface Management DIO 1 8 Data 8 Lines Handshake Bus Management To Other Devices ...

Page 270: ...s one of the more important management lines The state of this line determines how information on the data bus is to be interpreted IFC Interface Clear As the name implies the IFC line controls clearing of instru ments from the bus REN Remote Enable The REN line is used to place the instrument on the bus in the remote mode EOI End or Identify The EOI is usually used to mark the end of a multi byte...

Page 271: ...e is a controller NRFD and NDAC must be stable for at least 100nsec after ATN is set true Because of the possibility of a bus hang up many control lers have time out routines that display messages in case the transfer sequence stops for any reason Once all NDAC and NRFD are properly set the source sets DAV low indicating to accept ing devices that the byte on the data lines is now valid NRFD will ...

Page 272: ...ized in Table D 1 Table D 1 IEEE 488 bus command summary Command type Command State of ATN line Comments Uniline Multiline Universal Addressed Unaddressed Common SCPI REN Remote Enable EOI End Or Identify IFC Interface Clear ATN Attention SRQ Service Request LLO Local Lockout DCL Device Clear SPE Serial Poll Enable SPD Serial Poll Disable SDC Selective Device Clear GTL Go To Local UNL Unlisten UNT...

Page 273: ...ace Clear IFC is used to clear the interface and return all devices to the talker and listener idle states ATN Attention The controller sends ATN while transmitting addresses or multiline commands SRQ Service Request SRQ is asserted by a device when it requires service from a controller Universal multiline commands Universal commands are those multiline commands that require no addressing All devi...

Page 274: ... for example take a reading Although GET is an addressed command many devices respond to GET without address ing Address commands Addressed commands include two primary command groups and a secondary address group ATN is true when these commands are asserted The commands include LAG Listen Address Group These listen commands are derived from an instru ment s primary address and are used to address...

Page 275: ...e based on the instrument model defined by the Standard Commands for Programmable Instruments SCPI Consor tium s SCPI standard Generally these commands are sent as one or more ASCII characters that tell the device to perform a particular operation such as setting a range or closing a relay The IEEE 488 bus treats these commands as data in that ATN is false when the commands are transmit ted Comman...

Page 276: ...DC2 DC3 DC4 NAK SYN ETB CAN EM SUB ESC FS GS RS US LLO DCL PPU SPE SPD 1 B 2 A SP _ 2 B 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 3 A 0 1 2 3 4 5 6 7 8 9 3 B 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 UNL 4 A A B C D E F G H I J K L M N O 4 B 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 5 A P Q R S T U V W X Y Z 5 B 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 UNT 6 A a b c d e f g h i j k l m n o 6 B 7 A ...

Page 277: ...ote that ATN is true for both the listen command and the SDC command byte itself Table D 4 gives a typical common command sequence In this instance ATN is true while the instrument is being addressed but it is set high while sending the common command string Table D 3 Typical addressed multiline command sequence Step Command ATN state Data bus ASCII Hex Decimal 1 2 3 4 UNL LAG SDC Set low Stays lo...

Page 278: ...AV DATA VALID UNIVERSAL COMMAND GROUP ATN ATTENTION DCL DEVICE CLEAR IFC INTERFACE CLEAR REN REMOTE ENABLE SPD SERIAL POLL DISABLE SPE SERIAL POLL ENABLE ADDRESS COMMAND GROUP LISTEN TALK LAG LISTEN ADDRESS GROUP MLA MY LISTEN ADDRESS UNL UNLISTEN TAG TALK ADDRESS GROUP MTA MY TALK ADDRESS UNT UNTALK OTA OTHER TALK ADDRESS ADDRESSED COMMAND GROUP ACG ADDRESSED COMMAND GROUP GTL GO TO LOCAL SDC SEL...

Page 279: ...ities T5 exist only after the instrument has been addressed to talk L Listener Function The ability for the instrument to receive device dependent data over the bus from other devices is provided by the L function Listener capabilities L4 of the instrument exist only after it has been addressed to listen SR Service Request Function SR1 defines the ability of the instrument to request service from ...

Page 280: ...ized DT Device Trigger Function DT1 defines the ability of the Model 2520 to have readings triggered C Controller Function The instrument does not have controller capabilities C0 TE Extended Talker Function The instrument does not have extended talker capa bilities TE0 LE Extended Listener Function The instrument does not have extended listener capabilities LE0 E Bus Driver Type The instrument has...

Page 281: ...E IEEE 488andSCPI ConformanceInformation ...

Page 282: ...dard Std 488 2 1987 lists the documentation requirements Table E 1 provides a summary of the requirements and pro vides the information or references the manual for that information Table E 2 lists the coupled commands used by the Model 2520 The Model 2520 complies with SCPI version 1996 0 Table 14 1 through Table 14 10 in Section 14 lists the SCPI confirmed commands and the non SCPI commands impl...

Page 283: ... Common Commands implemented by Model 2520 Calibration query information Trigger macro for DDT Macro information Response to IDN identification Storage area for PUD and PUD Resource description for RDT and RDT Effects of RST RCL and SAV TST information Status register structure Sequential or overlapped commands Operation complete messages See Appendix D Cannot enter an invalid address Address chan...

Page 284: ... PULSe TRANsition STATe REN GTL SOURce 1 CURRent STEP SOURce 1 CURRent CENTer SOURce 1 CURRent SPAN SOURce 1 CURRent STEP SOURce 1 CURRent CENTer SOURce 1 CURRent SPAN SOURce 1 CURRent POINts SOURce 1 CURRent STEP SOURce 1 CURRent STARt SOURce 1 CURRent STOP SOURce 1 CURRent STEP SOURce 1 CURRent STARt SOURce 1 CURRent STOP SOURce 1 CURRent STEP SOURce 1 PULSe DELay TRACe POINts SOURce 1 PULSe WID...

Page 285: ...F MeasurementConsiderations ...

Page 286: ...e considerations is discussed in detail below Current pulse output circuit model Figure F 1 shows the Model 2520 current pulse output circuit model Components include the current source I and voltage clamp VC compliance circuit L is the cable inductance and the resistance of the laser diode is represented as RDUT Figure F 1 Model 2520 pulse output circuit model L L VC I RDUT Model 2520 I Current s...

Page 287: ...ely become a voltage source with a value equal to the compliance setting 10 5V maximum Under these conditions voltages in the circuit are related as follows Current while the source is in compliance then rises according the following relationship From the above discussion it is obvious that the rise time of the current pulse through the laser diode can be affected by the cable and other inductance...

Page 288: ...of cable Inductance is excessive in this case resulting in the first settled reading at 1 7µs as opposed to 1 5µs a 1µs delay was used before the pulse Figure F 3 shows the settled response of 0 45A into 16Ω also using 3m of cable The response is clean because di dt is much lower Figure F 2 Rise time of 4A current pulse 4 5 0 5 4 0 3 5 3 0 2 5 2 0 1 5 1 0 0 5 0 0 0 1 1 5 2 2 5 Current A Time µs ...

Page 289: ...rent source polarity if the laser diode anode is connected to the center conductor conversely select positive current source polarity if the laser diode anode is connected to the shield This method decreases rise time because it eliminates one of the two cables that connect the current source to the laser diode effectively cutting the cable inductance in half How ever the disadvantage is that one ...

Page 290: ... possible as shown in Figure F 4B Doing so will reduce the distributed induc tance and decrease the rise time of the current pulse Inductance for a loop of wire X inches by Y inches with a diameter D inches can be calcu lated as follows Thus a typical 1 inch square loop has an inductance of about 100nH while a typical 2 inch square loop has an inductance on the order of 170nH Figure F 4 Effects of...

Page 291: ...hows the same setup except for the addition of a two square inch loop in the source connection Figure F 5 Ideal response of 2A pulse using 10 inch cables Figure F 6 Response of 2A pulse with two square inch loop 2 5 0 8 2 0 1 5 1 0 0 5 0 0 0 1 1 6 1 8 2 2 Current A 0 6 1 2 1 4 2 2 5 0 8 2 0 1 5 1 0 0 5 0 0 0 1 1 6 1 8 2 2 Current A Time µs 0 6 1 2 1 4 2 2 4 ...

Page 292: ...are not connected together at the DUT In contrast the correct connections shown in Figure F 7B show sense connec tions made separately to the DUT with the sense leads connected as close to the DUT body as possible Figure F 7 Sense lead connections DUT A Incorrect sense leads not connected at DUT DUT B Correct sense leads connected at DUT Voltage Sense HI Current Output HI Current Output LO Voltage...

Page 293: ...ltage sense leads 1 4 inch away from the DUT Note the long settling tail corresponding to the DUT resistance 1 66Ω and the inductance formed by the leads Figure F 8 Response of 2A pulse with sense leads 1 4 inch away from DUT 2 5 0 8 2 0 1 5 1 0 0 5 0 0 0 1 1 6 1 8 2 2 Current A Time µs 0 6 1 2 1 4 2 2 4 ...

Page 294: ...sible Figure F 9B will reduce magnetic coupling and improve response Twisting the exposed sense leads and even the cables themselves may be necessary to reduce coupling to an acceptable level Figure F 9 Magnetic coupling DUT Connecting Cables Coupling Caused by Exposed Leads A Coupling caused by exposed leads DUT Connecting Cables Coupling Reduced by Shielding B Coupling reduced by shielding Volta...

Page 295: ...d reflections may strongly affect the performance of the optics system Measures must be taken to prevent the effects of unwanted reflection in an optical system Optical engineers have developed design methodologies to identify and control the negative side effects of differing indices of refraction while capturing the desired optical mechanisms Figure F 10 shows an optical pulse propagating throug...

Page 296: ...es to laser diodes dur ing testing Impedance matching and transmission line effects must be understood and managed to prevent damage or optimize test results Laser diode impedance matching The typical laser diode has a characteristic impedance of 2Ω to 6Ω This impedance is considerably lower than that of common coaxial cables which typically have characteris tic impedances in the range of 50Ω to 7...

Page 297: ...d would be used as the reference ground while connecting an oscil loscope to verify the forward voltage signal across the laser diode under test Figure F 11 Model 2520 output circuit model The voltage clamp circuit acts to limit maximum voltage as seen by the output of the pulse circuit Since the clamp circuit is not directly across the laser diode the voltage drop across the transmission line con...

Page 298: ...d This method however is not practical The electrical shielding must be compromised to pro vide access to the laser diode as shown in Figure F 13 The compromised shield provides access to the laser diode and upsets the continuity of the impedance of the transmission line To minimize the effects of the discontinuity the shield of the two compromised cable sections must be connected and the length o...

Page 299: ...commended cable connections for pulse sourcing and forward voltage measurement Note that all shields are connected together at the laser diode This scheme provides the minimal impedance mismatch and shortest electrical length for the pulse transmission path Figure F 14 Voltage measurement circuit model Figure F 15 Pulse source and forward voltage cable interconnections Analog to Digital Converter ...

Page 300: ...s voltage via the inner shield of the triax cable To minimize measurement error caused by noise and extraneous currents use only low noise triaxial cables See Generated currents page F 18 for more information Figure F 16 Model 2520 photo current measurement channels with dual bias supplies IN 1 14 Bias 1 Detector 1 IN 2 Bias 2 Detector 2 Chassis Ground Analog to Digital Converter 14 CLK Bias 1 Bia...

Page 301: ...tion Output VNOISE Input VNOISE 1 RF RDUT where Output VNOISE is noise seen at the output of the ammeter Input VNOISE is the noise seen at the input of the ammeter RF is the internal feedback resistance for the ammeter RDUT is the resistance of the DUT Table F 1 summarizes minimum recommended source resistance values for various mea surement ranges for the Model 2520 ammeters Note that the recomme...

Page 302: ...r ZF is the internal feedback impedance for the ammeter that is formed by CF and RF ZDUT is the internal impedance of the DUT that is formed by CDUT and RDUT Furthermore and Note that as CS increases in value ZDUT decreases in value thereby increasing the noise gain Again at the point where ZDUT ZF the input noise is amplified by a factor of two High source capacitance can also cause overshoot rin...

Page 303: ...lso be generated from external effects The external offset current also adds to the desired current and the ammeter again mea sures the sum of the currents IM IPD II0 IEO where IEO is the external offset current The two main sources for external offset currents are leaky photodiodes and increased photodiode leakage current caused by bias voltage Generally lower voltage bias values result in lower ...

Page 304: ...ups can create error signals that cause erratic or erroneous measurements The configuration shown in Figure F 18 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 mag...

Page 305: ...ons 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 panels ...

Page 306: ...ties 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 strong fields Note howeve...

Page 307: ... 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 special...

Page 308: ...G GPIB488 1Protocol ...

Page 309: ...e COMMUNICATIONS SETUP menu 2 Place the cursor on GPIB then press ENTER 3 Press ENTER at the ADDRESS prompt to display the GPIB PROTOCOL menu 4 Place the cursor on 488 1 and press ENTER 5 Use the EXIT key to back out of the menu structure When switching between the SCPI protocol and 488 1 protocol the instrument does not reset The GPIB protocol setting is saved in EEPROM and the unit will power up...

Page 310: ...d SENS1 VOLT RANG 10 OPC SENS2 CURR RANG READ READ READ The following command strings are valid SOUR1 CURRent STARt 0 1 STOP 0 5 STEP 0 1 SENS2 CURR RANG MAX READ When a query is sent either the data must be read back or a Device Clear DCL or Interface Clear IFC must be performed to reset the query When sending a command or query do not attempt to read data from the Model 2520 until the terminator...

Page 311: ... must be on OUTput 1 STATe ON before you can take readings The TRIG SOUR BUS and TRIG COUN INF commands are not supported by READ with the 488 1 protocol selected If you send one of these commands a DCL or IFC may be required to reset the GPIB Message available The MAV message available bit in the Serial Poll byte will be set when the query is fin ished being processed not when there is data avail...

Page 312: ...H ExamplePrograms ...

Page 313: ...S 5 0 or later or Quick Basic MS DOS version 5 0 or later or Windows 95 98 HP style Universal Language Driver CECHP EXE supplied with Keithley and CEC interface cards listed above General program instructions 1 With the power off connect the Model 2520 to the IEEE 488 interface of the com puter Be sure to use a shielded IEEE 488 cable for bus connections 2 Turn on the computer and the Model 2520 3...

Page 314: ...R1 VOLT PROT 5 5V LD source limit PRINT 1 OUTPUT 25 SOUR1 CURR POL POS Positive LD polarity PRINT 1 OUTPUT 25 SOUR1 FUNC PULS LD source pulse mode PRINT 1 OUTPUT 25 SOUR1 PULS DEL 100e 6 100us pulse delay PRINT 1 OUTPUT 25 SOUR1 PULS WIDT 10e 6 10us pulse width PRINT 1 OUTPUT 25 SOUR1 CURR LOW 10e 3 10mA low pulse level PRINT 1 OUTPUT 25 SOUR2 VOLT 20 20V detector 1 bias voltage PRINT 1 OUTPUT 25 ...

Page 315: ...RST Restore GPIB defaults PRINT 1 OUTPUT 25 FORM ELEM VOLT1 CURR2 CURR3 Voltage current data PRINT 1 OUTPUT 25 SENS1 VOLT RANG 5 5V measure range PRINT 1 OUTPUT 25 SOUR1 CURR RANG 0 5 500mA source range PRINT 1 OUTPUT 25 SOUR1 CURR STAR 10e 3 10mA start current PRINT 1 OUTPUT 25 SOUR1 CURR STOP 100e 3 100mA stop current PRINT 1 OUTPUT 25 SOUR1 CURR STEP 10e 3 10mA step current PRINT 1 OUTPUT 25 SO...

Page 316: ...ut terminator PRINT 1 OUTTERM LF Set output terminator PRINT 1 REMOTE 25 Put 2520 in remote PRINT 1 OUTPUT 25 RST Restore GPIB defaults PRINT 1 OUTPUT 25 FORM ELEM VOLT1 CURR2 CURR3 Voltage current data PRINT 1 OUTPUT 25 SOUR1 CURR MODE LIST Custom sweep mode PRINT 1 OUTPUT 25 SOUR1 LIST CURR 0 2 0 1 0 4 0 3 0 5 I list PRINT 1 OUTPUT 25 SOUR1 LIST DEL 7e 3 4e 3 2e 3 8e 3 1e 3 D list PRINT 1 OUTPUT...

Page 317: ...I ContinuousPulseMode ...

Page 318: ...sting in the pulse regime is done to minimize the heating of the diode junction so duty cycles are typically 1 or less By minimizing the heating testing can be performed on the laser diode as soon as the lasing cavity is defined at the wafer level for VCSELs and at the bar level for edge emitting laser diodes This early testing permits pass fail and other grading decisions to be performed before a...

Page 319: ...s the PW key 2 Use the EDIT keys to set the desired pulse width Press ENTER when finished Set the desired Pulse Delay in other words Pulse off time 1 Press the DELAY key 2 Use the EDIT keys to set the pulse delay to 000 33ms Press ENTER when finished Set the desired current source value 1 Press the IL key 2 Use the EDIT keys to set the desired current value Press ENTER when finished To turn on the...

Page 320: ...al time meaning that the minimum pulse delay time is about 2ms 3 Trigger count Continuous Pulse This mode is explained above It is similar to count Inf but there are no measurements in this mode and the set pulse width equals the actual pulse width Command Comment RST SOUR1 CURR MODE FIX SOUR1 CURR 0 2 SOUR1 PULS DEL 0 00033 SOUR1 PULS WIDT 0 000001 TRIG COUN CONTINUOUS OUTP ON SYST KEY 20 SDC OUT...

Page 321: ...s subsystem 14 49 SYSTem subsystem 14 51 TRACe subsystem 14 56 Trigger subsystem 14 57 Command summary CALCulate 14 3 DISPlay 14 5 FORMat 14 6 OUTPut 14 6 SENSe 14 7 SOURce 14 9 STATus 14 12 SYSTem 14 13 TRACe 14 13 TRIGger 14 14 Commands Address D 9 Addressed multiline D 9 Common see common commands 12 1 Condition register 11 17 Coupled E 4 Custom sweep 7 10 Error queue 11 21 Event enable registe...

Page 322: ... diode F 2 Pulse sync output 9 9 Remote interlock 2 6 RS 232 10 18 Sense lead F 8 Testhead 2 3 Connectors CURRENT OUTPUT 2 6 DETECTOR 1 9 Digital I O 1 8 GPIB 1 8 Laser diode 1 9 MAINFRAME 1 10 Pulse sync 1 8 RS 232 1 8 Signal 2 5 TESTHEAD 1 8 Triax DETECTOR 2 6 Trigger link 1 8 VOLTAGE SENSE 2 6 Contact information 1 2 Continuous pulse mode I 2 Counter 8 4 8 12 Current pulse output circuit model ...

Page 323: ...rror queue 11 21 Remote trigger 8 14 RS 232 programming example 10 20 Staircase sweep programming 7 9 Status byte programming example 11 10 Sweep and list program examples 14 44 F Factory default settings 1 15 Filter 6 4 8 4 8 12 Averaging 6 4 Commands 6 6 Configuration 6 5 Configure and control 14 30 Control 6 5 Programming example 6 6 Remote programming 6 5 Fixed mode Front panel pulse parameter...

Page 324: ...key presses 14 53 L Laser diode Configuring measurements 3 12 Configuring source 3 10 Current source 4 4 Current source ranges 3 2 6 3 Front panel test procedure 4 4 Front panel testing 4 3 Impedance matching F 12 Math function 14 15 Measurement function 4 4 Optimizing connections F 2 Polarity 3 6 Remote testing 4 5 Select laser diode voltage measurement range 14 28 Source and measure capabilities...

Page 325: ...us and error 1 13 B 1 MX B math function 6 7 Set parameters 14 15 N Noise Source Impedance F 17 O Operating boundaries see Limit lines 5 10 Operation overview 3 2 Options 1 3 Output circuit model F 13 OUTPut subsystem 14 27 Output trigger 8 4 Specifications 8 6 Output triggers 8 13 P Parameters Front panel pulse 5 4 Remote pulse 5 6 Photodiode Configuring measurements 3 12 Current measurement rang...

Page 326: ... event register 11 11 Status byte register 11 8 Status register sets 11 11 Related modes I 4 Remote configuration over GPIB IEEE 488 I 4 Remote operation 10 1 Differences to local operation 10 2 Selecting an interface 10 2 Trigger model 8 9 Remote programming Digital output control 9 5 Display 1 14 Filter 6 5 Laser diode testing 4 5 Math functions 6 9 Pulse parameters 5 6 Range 6 3 Setups 1 17 Swe...

Page 327: ...eters 5 6 Start of test SOT line 9 3 Status and error messages 1 13 B 1 Status byte and SRQ 11 2 11 7 Commands 11 10 Status register format 14 26 Status register sets 11 2 11 11 Status structure 11 1 STATus subsystem 14 49 Sweep Averaging filter during 6 5 Configure 14 37 Configuring 7 5 Custom 5 8 7 4 Custom sweep commands 7 10 Custom waveform 5 9 Data storage 5 12 Front panel operation 7 5 Linea...

Page 328: ...Triggering 8 1 Configuring 8 7 Front panel operation 8 2 Remote 8 9 Triggers Input 8 3 8 6 8 11 Output 8 13 U User setups see Setups 1 14 V Voltage Burden F 20 Voltage measurement circuit model F 15 W Warranty information 1 2 ...

Page 329: ...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 560 025 080 212 8027 Fax 080 212 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...

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