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User`s Manual - Stanford Research Systems

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1. 2 9 25 2 Grounded configurations 2 10 2 6 Error messages rara ee ED ae ous 2 12 2 6 1 Firmware corruption 2 12 262 Configuration lost 24464 e Rs 2 12 26 0 Calibration lost die exa 2 12 Remote Operation 3 1 3 1 Index of commands a 3 2 3 2 Alphabetic list of commands 3 3 33 Introduction oaoa a 3 5 3 83 1 Interface configuration 3 5 3 3 2 B ffers 2 24 44 25 4 e a dox ee As 3 5 3 4 Commands eee ee 3 6 3 4 1 Command syntax o oo o 3 6 3 42 Notation 3 7 34 3 JEXamples ilis ces aha nee ARE aa 3 7 3 4 4 Configuration commands 3 8 3 45 Setting commands 3 11 3 4 6 Setup commands 2442 e002 exes 2 3 11 3 4 7 Interface commands 3 11 3 4 8 Status commands oaa 3 12 3 5 Stat smodel 2 kecu Sb ee ee a 3 16 3 5 1 Status byte SB na oa wae od aoe ess 3 16 3 5 2 Service request enable SRE 3 17 3 5 3 Standard event status ESR 3 17 Fuse and ac Line A 1 A 1 Power Entry module 42 4 r4 52050664 8 A 1 A 2 ac voltage selector s gw e a a A A 1 ASRS CS580 Voltage Controlled Current Source Contents iii A 3 Fuse installation CS580 Voltage Controlled Current Source ASRS iv Contents ASRS CS580 Voltage Controlled Current Source General Information Safety and Preparation for Use La W
2. ASRS CS580 Voltage Controlled Current Source 14 AC modulation 1 4 AC modulation Figure 1 1 Two typical C5580 configurations On the left the inner shield is connected to the current return and the source is floating On the right the inner shield is connected to the driven guard and the source is grounded return current must be wired back to the instrument through the Return node This can either be via the inner shield if SHIELD is configured for Return or else by the MONITOR Return terminal the black banana receptacle When ISOLATION is configured as Ground the Return node of the current source is electrically tied to chassis ground In this configuration return current may flow back to the source via any path to chassis ground although in practice the outer shield is typically used In the preceding example we first operated with the CS580 in Float mode with SHIELD set to Return see Figure 1 1 left hand side The current source s circuit flowed from the center conductor red clip through the 1kQ resistor then to the inner shield black clip back to the source The Monitor voltage showed the voltage across the resistor as measured by the internal voltage buffer while the Resistor voltmeter measured the same voltage directly When the configuration was changed to SHIELD Guard and ISOLA TION Ground see Figure 1 1 right hand side initially there was no return path for current and the CS
3. If available on the function generator vary the waveform from sine to square triangle and sawtooth Verify that similar wave forms appear on Channel 2 Return the function generator to sine wave output Try turning the GAIN knob to select 10 mAJ V and verify the CS580 does not allow the gain to change with the output on and analog input enabled Press the OUTPUT Enable button to disable the current out put and then turn the knob to select 10 mA V Press the OUTPUT Enable button again to re enable the current out put and verify that Channel 2 on the oscilloscope now shows a 10 V pp If necessary press the ADJUST knob to select DC current and then turn ADJUST to select 1 0 mA Verify that Channel 2 on the oscilloscope is now offset by 1 V Press the INPUT Enable button to disable the analog input and verify that Channel 2 on the oscilloscope now shows a flat 1V dc Turn the knob back to 1 mA V and press INPUT Enable again Verify that Channel 2 now shows a 1V pp ac signal still offset by 1 V ASRS CS580 Voltage Controlled Current Source 15 Compliance limit and high impedance monitoring 1 7 1 4 2 Discussion In this example the analog input was used to create arbitrary ac currents When configured for 1mA V the CS580 was outputting 1 0mA pp in response to the 1 0 V pp analog input Note that gain changes could only be performed with the output disabled or the input disabl
4. connected from the current source When set to SOUT ON the center conductor is electrically connected to the CS580 current source out put node Note that the current source output is controlled indepen dently of the analog input INPT CS580 Voltage Controlled Current Source f SRS Remote Operation Example The SOUT command is equivalent to pressing the OUTPUT Enable button SOUT ON ASRS CS580 Voltage Controlled Current Source 3 4 Commands 3 11 3 4 5 Setting commands CURR f DC current Set query the internally generated DC current to f in amperes The default value is CURR 0 0 Note that the allowable range for CURR depends on the GAIN setting the DC current range is always 2 V times the gain for example when GAIN G10uA the allowed range for CURR is 20E 6 to 20E 6 The CURR command is equivalent to the front panel DC current setting which can be modified with the ADJUST knob Example CURR 1 25e 9 VOLT g Compliance voltage Set query the compliance voltage limit to g in volts The default value is VOLT 10 0 The allowable range for VOLT is always 0 to 50 The VOLT command is equivalent to the front panel Compliance voltage setting which can be modified with the ADJUST knob Example VOLT 35 3 4 6 Setup commands ALRM z Audible alarms Set query audible alarms to Z OFF 0 ON 1 Note that all sounds that are not key
5. be used Note that the setting cannot be modified when the analog input is enabled and the current output is enabled Also note that the Overload indicator reflects the combination of both input voltage and the internally generated dc current see below In addition to the analog programming voltage the CS580 has an internal dc current generator This setting is controlled either from the front panel or remotely and is always active when the current output is enabled even if the analog input section is disabled Briefly pressing the knob toggles the adjustment focus between DC current and Compliance voltage While DC current is selected the current can be set to zero by pressing and holding the knob in for several seconds The range of dc current setting is controlled by the gain selection See the specification table in section on page ix for details Note that when increasing gain settings the dc current value remains un changed But when decreasing gain if the previous setting becomes out of range the value is forced to the maximum For example if the dc current is set to 8 45 yA while on the 10 LA V gain and then is turned down to the 1 uA V setting the dc current is forced to 2 uA the maximim value for the new gain setting ASRS CS580 Voltage Controlled Current Source 2 4 Instrument overview 2 7 2 4 3 Compliance voltage The Compliance voltage setting limits the voltage that can be pro duced on the current o
6. referred to input Offset drift 1 mV C referred to input Specifications are for the internal dc current source with external analog input off Gain Max output DC accuracy Resolution Drift typ 1nA V 2nA 0 5 10pA 100fA 100 ppm C 100 fA C 10nA V 20nA 0 5 10pA 1pA 100 ppm C 200fA C 100nA V 200nA 0 5 100pA 10pA 100 ppm C 2pA C luA V 2uA 0 196 1nA 100pA 50 ppm C 20 pA C 10 uA V 20uA 01 10nA 1nA 50 ppm C 200 pA C 100 uA V 200 uA 0 1 100nA 10nA 50 ppm C 2nA PC 1mA V 2mA 0 1 1uA 100nA 50 ppm C 20nA C 10mA V 20mA 0 1 10uA 1pA 50 ppm C 200 nA C 50mA V 100mA 0 196 50uA 10uA 50ppm C 1 uA C Noise Noise density RMS noise inp off Gain Input off Inputon 0 1to10 Hz gt 10 Hz 1nA V 10fA VHz 10fA VHz 20fA 50 pA 10nA V 20fA VHz 20fA VHz 80fA 50 pA 100nA V 60fA VHz 60fA VHz 400fA 300 pA 1uA V 300fA VHz 400fA VHz 4pA 1nA 104A V 3pA VHz 4pA VHz 40pA 5nA 100 A V 30pA VHz 40pA VHz 400pA 40nA 1mA V 300 pA VHz 400 pA VHz 4nA 400nA 10mA V 3nA VHz 4nA VHz_ 40nA 4 uA 50mA V 15nA VHz 20nA VHz 200nA 20 uA Remote Interfaces RS 232 DB 9 connector 9600 baud Optical fiber Connection to SX199 Optical Interface Controller Provides isolated connectivity to GPIB RS 232 and Ethernet CS580 Voltage Controlled Current Source
7. 3 8 Speed SHLD z 3 9 Inner shield ISOL z 3 9 Isolation SOUT z 3 9 Output Settings CURR f 3 11 DC current VOLT g 3 11 Compliance voltage Setup ALRM z 3 11 Audible alarms Interface IDN 3 11 Identify TOKN 2 3 12 Token Mode OPC 3 12 Operation complete RST 3 12 Reset Status OVLD 3 13 Overload STB 1 3 13 Status byte SRE i j 3 13 Service request enable ESR i 3 13 Standard event status ESE 61 j 3 14 Standard event status enable CLS 3 14 Clear status LEXE 3 14 Last execution error LCME 3 15 Last command error ASRS CS580 Voltage Controlled Current Source 3 2 Alphabetic list of commands 3 2 Alphabetic list of commands CLS ESE 5 ESR i IDN OPC RST SRE 6 j STB 1 3 14 Clear status 3 14 Standard event status enable 3 13 Standard event status 3 11 Identify 3 12 Operation complete 3 12 Reset 3 13 Service request enable 3 13 Status byte A ALRM z 3 11 Audible alarms C CURR f 3 11 DC current G GAIN z 3 8 Gain INPT z ISOL 2 3 8 Analog input 3 9 Isolation L LCME LEXE 3 15 Last command error 3 14 Last execution error O OVLD 3 13 Overload R RESP z 3 8 Speed S SHLD z SOUT z 3 9 Inner shield 3 9 Output TOKN z 3 12 Token Mode CS580 Voltage Controlled Current Sour
8. clicks are considered alarms for the purpose of the ALRM command There is no corresponding front panel methdo to access this command it is exclusive to the remote interface 3 4 7 Interface commands IDN Identify Query the CS580 identification string The response is formatted as Stanford Research Systems CS580 s n ver where is the 6 digit serial number and is the firmware revision level Example IDN CS580 Voltage Controlled Current Source f SRS Remote Operation Stanford Research Systems CS580 s n098023 ver1 00 TOKN z Example Token Mode Set query the token response mode to Z OFF 0 ON 1 Token response mode controls the formatting of response messages generated by the CS580 to remote queries of token type values When TOKN OFF the CS580 responds with the numeric version of the token quantity When TOKN ON the text version is returned TOKN ON OPC Example Operation complete The set form OPC will set the OPC bit in the Standard Event Status register the query form OPC will return the value 1 OPC is useful for pacing streams of remote commands the OPC command will not be processed by the command execution of the CS580 until all preceding commands have been executed OPC 1 RST 3 4 8 Status commands Reset Reset the CS580 to its default configuration The following commands are internally excecuted upon
9. fingers CS580 Voltage Controlled Current Source SRS Fuse and ac Line NOT here Insert Here When the fuse holder is installed in the dual metric position it will normally release as soon as the door is opened Install one 1 AG size 0 25 x 1 25 fuse or two 2 metric size 5 x 20 mm fuses as shown Install fuses on one side only do not install both AG and metric together at the same time North American Metric single fuse installation dual fuse installation Also note that when installing the North American AG fuse the fuse is not centered on the plastic retaining hook but rather shifted towards the right hand side see image above left If the fuse is not properly aligned the fuse holder will not seat properly and line voltage will not be provided to the instru ment Replace the fuse holder into housing fuse first Be sure to align the circular opening on the fuse holder with the orienting pin within the power entry module 7 Swing and push to snap the door back in place ASRS CS580 Voltage Controlled Current Source
10. possible for the ac tual output voltage to overshoot the compliance voltage limit by up to 1 5 V Users should adjust the compliance voltage setting accord ingly especially in situations where the operating voltage is near the maximum allowable value for the load 2 4 3 2 Active loads When sinking corrent from any active load care must be taken to ensure that the active load voltage is within the compliance voltage setting of the CS580 2 4 4 Current source The current source circutry forms the heart of the CS580 A voltage controlled current source with 9 separate gain resistors provide the output current through the triaxial connector CS580 Voltage Controlled Current Source SRS 2 8 Operation 2 4 5 Speed setting 2 4 6 Guard buffer 2 4 6 1 Triax inner shield 2 4 6 2 Banana jack The front panel SPEED section allows the user to switch between Fast and Slow configurations by pressing the Speed button When set to Slow a 470 pF capacitor is switched in across the current source output effectively limiting its bandwidth Note that the actual re sponse time from this filter depends on the load impedance with an effective time constant given roughly by the product of the load resis tance with the total output capacitance 470 pF plus cable capacitance plus load capacitance The output node of the current source is monitored with an electrometer grade unity gain voltage buffer This element serves two p
11. source fully disconnected from chassis ground To prevent electric shock and or damage to the CS580 do not exceed 250 V between any of the floating nodes of the current source and chassis ground Isolation is provided for maximum flexibility for situations where either ground is established at some fixed point in the circuit other than the CS580 as a means to avoid ground loops or for cases where the current is connected to an external low voltage source 2 5 1 1 Floating source return current through inner shield This configuration is selected when ISOLATION is set to Float and SHIELD is set to Return Schematically the configuration is shown in Figure 2 3 CS580 Voltage Controlled Current Source f SRS 2 10 Operation Figure 2 3 Floating source return shield The inner shield is connected to the current return and the source is floating Return current can flow back from the external load through the inner shield of the triax connector The voltage on the load may be monitored between the red and black banana jacks in the MONITOR block but remember that these terminals are also floating with the current source 2 5 1 2 Floating source inner shield as guard This configuration is selected when ISOLATION is set to Float and SHIELD is set to Guard Schematically the configuration is shown in Figure 2 4 CONFIGURATION Guard Return Figure 2 4 Floating source guard shield The inner shield is conne
12. the de output current or the compliance voltage limit No live readings are made by the CS580 and the numeric display is statically driven to eliminate any possible switching noise Instrument overview Input section A functional overview of the CS580 with its main sections is given below A block diagram of the CS580 is shown in Figure 2 2 A key feature of the CS580 is its floating power design The entire output circuit is powered by an isolated power supply allowing the user to establish the ground reference anywhere within their setup The analog input section of the CS580 consists of a 100 kQ input impedance unity gain isolation amplifier Isolation is required to bring the user s voltage input from the front panel BNC referenced to chassis ground to the floating circuitry of the current source This signal path can be enabled or disabled by remote command or by pressing the INPUT Enable button CS580 Voltage Controlled Current Source SRS 2 6 Operation Compliance voltage set DC current set Isolation Current amplifier source Output Input 2 4 2 DC current Input enable Guard Return Figure 2 2 The CS580 block diagram This analog programming voltage is converted to current by the selected gain setting which can be set from 1 nA V up to 50 mA V in nine 9 ranges The analog input is dc coupled meaning that any combination of ac and dc inputs within the input range of 2 V may
13. turn to Chapter 2 Users who prefer to jump in and begin using the CS580 first should continue with this Chapter where a series of step by step procedures are given to verify the basic performance of the instrument This will also provide a quick introduction to the CS580 and how it is operated Chapter 3 discusses remote operation of the CS580 over the optical fiber or RS 232 interface This chapter provides step by step instructions for verifying the basic operation of the CS580 In addition to confirming proper operation it provides a good introduction to operating the current source To perform all the steps described in this chapter you will need 1 a collection of several BNC cables and tees 2 the CS580 triax to alligator cable 3 a dual banana to BNC female adapter 4 a collection of leaded resistors 100 1 KQ 100 kQ 10 MO and optionally 1GO al a function generator 6 two multimeters either hand held type or benchtop 7 a general purpose 2 channel oscilloscope with a 10 MQ 10x passive probe with ground clip 1 2 2 Preparations before use N CAUTION 1 Before using the instrument verify the rear panel power entry module is properly configured for the power line voltage in your region Applying power with improper setting of the line voltage selector will result in significant damage to the CS580 2 Turn the rear panel Power switch to off 3 Plug in the AC line cord to the rear panel po
14. 580 source went into compliance voltage limiting The Monitor voltage showed the center conduc tor reached the limit voltage at it s default value of 10 V but no current was flowing as could be seen by the Resistor voltmeter reading 0 V When the black clip was removed from the 1 KO resistor and replace with the green clip a return path was again established for the cur rent Now the instrument came back out of compliance limiting and again both voltmeters reported the voltage across the resistor This exercise demonstrates using the analog voltage input to generate ac current outputs with the CS580 CS580 Voltage Controlled Current Source SRS 1 6 Getting Started 1 4 1 Procedure 10 11 If not already done follow the initial preparations described in section 1 2 2 Set the function generator to output a sine wave 1 0 V peak to peak at 1 kHz Using the 10 MO 10x probe connect the probe to the same side of the 1 KO resistor as the red alligator clip Connect the probe ground clip to the opposite side of the 1 KO resistor adjacent to the black alligator clip from the CS580 Using the GAIN knob select 1 mA V Trigger the oscilloscope on Channel 1 the function generator signal and verify that Channel 2 the scope probe shows now signal Press the OUTPUT Enable button to turn on the current out put Verify that Channel 2 on the oscilloscope shows a similar signal
15. ARNING AC line voltage N CAUTION Line cord Service Dangerous voltages capable of causing injury or death are present in this instrument Do not remove the product covers or panels Do not apply power or operate the product without all covers and panels in place The CS580 Voltage Controlled Current Source operates from a 100 V 120 V 220 V 230 V or 240 V nominal ac power source having a line frequency of 50 Hz or 60 Hz Before connecting the power cord to a power source verify that the LINE VOLTAGE SELECTOR located in the rear panel power entry module is set so that the correct ac line voltage value is visible For operation with 220 V ac power the LINE VOLTAGE SELECTOR should be set to 230 V The CS580 Voltage Controlled Current Source will be damaged if operated with the LINE VOLTAGE SELECTOR set for the wrong ac line voltage or if the wrong fuses are installed Verify that the correct line fuses are installed before connecting the line cord For 100 V 120 V use 1 A fuses for 220 V 230 V 240 V use 0 5 A fuses See appendix A for detailed instructions The CS580 Voltage Controlled Current Source has a detachable three wire power cord for connection to the power source and to a protec tive ground The chassis of the instrument is connected to the outlet ground to protect against electrical shock Always use an outlet which has a properly connected protective ground The CS580 Voltage Controlled Current Source does n
16. ASRS x General Information General Parameter Specification Temperature 0 C to 40 C non condensing Power lt 30 W 100 120 220 240 VAC 50 60 Hz Dimensions 8 3 W x 3 5 H x 13 D Weight 10 lbs Fuse one 1 AG size 0 25 x 1 25 or two 2 metric size 5 x 20 mm slow blow ASRS CS580 Voltage Controlled Current Source 1 Getting Started In This Chapter This chapter provides step by step instruction to get started quickly with the CS580 Voltage Controlled Current Source Refer to chapter 2 for a more complete introduction to the CS580 1 1 1 2 1 3 1 4 1 5 How to use this manual 1 2 Preliminaries 525 9 6 a Rs 1 2 121 Equipment needed 0 mx PES 1 2 1 2 2 Preparations before use os Cue Ook ee A 1 2 DC current and monitor output 1 3 13 1 Procedure llle 1 3 13 2 Discussion 1 4 AC modulation en 1 5 141 Procedure llle 1 6 142 DISCUSSION E K a T aC E Ble ee Re EY ab 1 7 Compliance limit and high impedance monitoring 1 7 EST POCO UTE ici i onai AS TR Lu 1 7 15 2 Discussi0M 1 8 1 2 Getting Started 1 1 How to use this manual 1 2 Preliminaries 1 2 1 Equipment needed Two possible starting points are available to new users of the CS580 Those who want to begin with an overview to the functional layout of the instrument should
17. LD z Example Inner shield Set query the inner shield connection mode to Z GUARD 0 RETURN 1 When switched to SHLD GUARD the triax inner shield is connected to the voltage buffer output providing a driven guard function When switched to SHLD RETURN the inner shield is tied to the current source return node The SHLD command is equivalent to pressing the Shield button Note that the SHLD command may not be set while the output is enabled SHLD GUARD ISOL z Example Isolation Set query the current source isolation mode to Z GROUND 0 FLOAT 1 When switched to ISOL FLOAT the current source is electrically iso lated from chassis ground to complete the circuit current must be returned to the CS580 through the Return node either at the black banana receptacle or when configured as SHLD RETURN on the inner shield When set to ISOL GROUND the current source return node is elec trically connected to chassis ground in this configuration return current may also be carried on the triax outer shield Note that the ISOL command may not be set while the output is enabled The ISOL command is equivalent to pressing the Ground button ISOL FLOAT SOUT z Output labelcemd SOUT Set query the current source output mode to Z OFF 0 ON 1 The current source output is enabled or disabled using the SOUT command When set to SOUT OFF the triax center conductor is dis
18. Operation and Service Manual Voltage Controlled Current Source CS580 SRS Stanford Research Systems Revision 1 0 e October 8 2015 Certification Stanford Research Systems certifies that this product met its published specifications at the time of shipment Warranty This Stanford Research Systems product is warranted against defects in materials and workman ship for a period of one 1 year from the date of shipment Service For warranty service or repair this product must be returned to a Stanford Research Systems authorized service facility Contact Stanford Research Systems or an authorized representative before returning this product for repair Information in this document is subject to change without notice Copyright Stanford Research Systems Inc 2015 All rights reserved Stanford Research Systems Inc 1290 D Reamwood Avenue Sunnyvale CA 94089 USA Phone 408 744 9040 e Fax 408 744 9049 www thinkSRS com e e mail info thinkSRS com Printed in U S A Document number 9 01709 903 SRS CS580 Voltage Controlled Current Source Contents General Information Safety and Preparation for Use SyvIBbOlS cce is E Ute e as Da ad s Notation uta dh od de aes ds ui ew eh oh A ad Spe ifi ationsi dice ah se Ge Sve SoE A dq d 1 Getting Started 11 Howto use this manual 1 2 Preliminaries lala DR Min as 1 2 1 Equipment needed aci n er od 1 2 2 Preparations before use e ut
19. V 230V amp 220V 240V 5 Orient indicator pin to point up when desired line voltage is readable at the bottom note that when indicator pin is fixed successive voltages are selected by rotating the card 90 clock wise 6 Insert the voltage selector card into the housing with the printed side of the card facing the fuse and IEC connector Ori ent the card so the text showing the desired voltage is inserted first 7 Replace the fuse cover and snap into position verifying the indicator pin is showing at the desired line voltage 8 If necessary replace the fuse for the appropriate rating based on line voltage A 3 Fuse installation Two options are available for fusing the CS580 North American style single fuse and metric dual fuse installation The fuse holder is reversible to accommodate both styles 4 SRS CS580 Voltage Controlled Current Source A 3 Fuse installation A 3 The following steps describe how to install or replace the fuse s 1 Disconnect and remove the power cord Section A A 3 Gently lift the entire door back away from the rear panel of the CS580 Lift away approximately 0 25 6 mm Once lifted the door will pivot on its hinge to expose the fuse holder L Lob i 4 When the fuse holder is installed in the single fuse North American position apply a screwdriver or small needle nose plyers as shown and gently lift out Use a tool as shown do not use
20. a pO oe w 13 DC current and monitor output 13 31 Procedure 13 2 Discussion 14 AC modulation leen T T Procedure i 232 o on 142 Discussion 22er es 15 Compliance limit and high impedance monitoring 2 Operation 2 1 2 2 151 Procedure a 15 2 DISCUSSION n ne o R E ER EE RSS Navigating the front panel ini wg 2 1d Grains A AA A 2 102 Settings A Ae Ade S398 eR Rye KB wh BAO JAdTUSL Zo se Sv Gj bla Me Bi Bh Me Be wee ye WE 214 Configuration aoaaa vet ex uic 2d05 IND iaa A 216 Speed so iau s IRE VR E WE E ZEZ Smells ERE US 2 1 8 Isolation 00002 eee 21 90 MOROS 20 kre EME een a E MO OUI e rr verses Brey BLES ose DE OR DIIS Poweron KEYS ess reos be BRAS A E 2 2 1 Power on reset 222 Power on identify ii Contents 2 3 Introduction to the instrument 2 5 2 3 1 Clock stopping architecture 2 5 24 Instrument overview 2 5 2 4 1 Input section aaa aaa 2 5 24 2 DC current 0004 2 6 243 Compliance voltage 2 7 2 44 Current source 2 7 2 4 5 Speed setting 4 sci s ay pap uetus DA 2 8 2 4 6 Guard buffer 2 8 247 Isolation 2 9 2 48 UME ae eoe Pe hw ee RRA em deg 2 9 2 5 Configurations and grounding 2 9 25 1 Floating configurations
21. cal If an input buffer overflows then all data in the input buffer are discarded and an error is recorded in the ESR status register CS580 Voltage Controlled Current Source SRS 3 6 Remote Operation 3 4 Commands 3 4 1 Command syntax tokens This section provides syntax and operational descriptions for remote commands The four letter mnemonic shown in CAPS in each command se quence specifies the command The rest of the sequence consists of parameters Commands may take either set or query form depending on whether the character follows the mnemonic Set only commands are listed without the query only commands show the after the mnemonic and optionally query commands are marked with a Parameters shown in and are not always required Parameters in are required to set a value and should be omitted for queries Parameters in are optional in both set and query commands Pa rameters listed without surrounding characters are always required Do not send or or as part of the command Multiple parameters are separated by commas Multiple commands may be sent on one command line by separating them with semi colons so long as the input buffer does not overflow Commands are terminated by either CR or LF characters Null commands and whitespaces are ignored Execution of the command does not begin until the command terminator is received Token parameter
22. cator Connect one multimeter to the MONITOR output and set the multimeter to read volts Label this voltmeter Monitor Connect the second voltmeter using test leads to measure the voltage across the 1 KQ resistor and set the multimeter to read volts Label this voltmeter Resistor Ensure the DC current indicator is illuminated in the SET TINGS block If not briefly press in the ADJUST knob Turn the ADJUST knob to set DC current to 0 250 mA Verify that both voltmeters still displays approximately 0 V CS580 Voltage Controlled Current Source f SRS Getting Started 1 3 2 Discussion 6 Press the OUTPUT Enable button to turn on the output The On indicator should light and both voltmeters should display approximately 250 mV 7 Turn the ADJUST knob to set the DC current to 1 000 mA The voltemeters should now display 1 V 8 Press the OUTPUT Enable button to turn off the output and then press the Shield button to select Guard Press the key Ground button to select Ground 9 Press the OUTPUT Enable button to turn on the output again The Compliance limit indicator should light indicating the out put reached the limit voltage presently 10 V The Monitor meter should read near 10 V while the Resistor meter should read near 0 V 10 Carefully disconnect the triax black alligator lead from the re sistor and then connect the triax green alligator lead to the r
23. ce ASRS Remote Operation V VOLT g 3 11 Compliance voltage ASRS CS580 Voltage Controlled Current Source 3 3 Introduction 3 3 Introduction Remote operation of the C5580 is through a simple command lan guage documented in this chapter Both set and query forms of most commands are supported allowing the user complete control of the current source from a remote computer through RS 232 or through the optical fiber and the SX199 interface to GPIB RS 232 or ethernet interfaces Where applicable the corresponding front panel interface to each command is also indicated Most instrument settings are retained in non volatile memory Upon power on these settings are restored to their values before the power was turned off Where appropriate the default value for parameters is listed in boldface in the command descriptions 3 3 1 Interface configuration 3 3 2 Buffers Both RS 232 and optical fiber interfaces are fixed configuration 9600 baud 8 bit with no parity or flow control The CS580 stores incoming bytes from the remote interfaces in sepa rate 128 byte input buffers Characters accumulate in the input buffer until a command terminator CR or LF is received at which point the message is parsed and enqueued for execution Query responses from the CS580 are buffered in interface specific 256 byte output queues Queries are returned to the interface from which they were received RS 232 or opti
24. cted to the driven guard buffer and the source is floating Return current in this configuration must flow back to the C5580 through the black banana jack in the MONITOR block as this is the only connection available for return current 2 5 2 Grounded configurations These next two configurations shown have the current source return connected to the outer shield of the triax and also to chassis ground through a low resistance inductor SRS CS580 Voltage Controlled Current Source 25 Configurations and grounding 2 11 2 5 2 1 Grounded source inner shield as current return This configuration is selected when ISOLATION is set to Ground and SHIELD is set to Return Schematically the configuration is shown in Figure 2 5 CONFIGURATION Figure 2 5 Grounded source return shield The inner shield is connected to the current return and the source is grounded Return current can flow back from the external load through the inner or outer shield of the triax connector The voltage on the load may be monitored between the red and black banana jacks in the MONITOR block 2 5 2 2 Grounded source inner shield as guard This configuration is selected when ISOLATION is set to Ground and SHIELD is set to Guard Schematically the configuration is shown in Figure 2 6 CONFIGURATION Figure 2 6 Grounded source guard shield The inner shield is connected to the driven guard buffer and the source is grounded Return c
25. e Controlled Current Source 25 Configurations and grounding 2 9 2 4 7 Isolation 2 4 8 Output The entire current source section of the CS580 can be isolated to float the source relative to chassis ground Control of this feature is through the Ground button which toggles the ISOLATION setting between Float and Ground When set to Ground the return node of the current source is connected to chassis ground through a low resistance inductor to help minimize noise When set to Float there is no connection internal to the CS580 between the current source circuit and ground The current output of the CS580 is produced on a three lug triaxial connector located on the front panel The outer shield of this connec tor is always connected to chassis ground through a low resistance inductor The inner shield terminal of the triax is controlled by the SHIELD block described previously in section 2 4 6 1 The center conductor is the current source output When OUTPUT is set to On the current source circuit is active and the center conductor is con nected to the output of the source When not on the center conductor is disconnected from the internal source circuitry and the source is disabled 2 5 Configurations and grounding There are four distinct configurations of the current source based on the user settings for ISOLATION and SHIELD 2 5 1 Floating configurations A WARNING The first two configurations shown have the current
26. ed Additional dc current set from the front panel is added to the analog input signal 1 5 Compliance limit and high impedance monitoring This exercise generates low level currents into a relatively high impedance load and will demonstrate the compliance limit function as well as using the monitor output to measure a high impedance load 1 5 1 Procedure 1 If not already done follow the initial preparations described in section 1 2 2 but connect the 1 GO resistor rather than the 1 kQ resistor to the triax cable Be careful not to touch the resistor body with your fingers as skin oils will effectively short out the high impedance of the resistor If no GQ resistor is available use a 10 MQ instead 2 Optionally Arrange the resistor inside a small metal box with the alligator leads coming out supported on plastic or ceramic so that neither end of the resistor can touch the metal box Clip the green alligator lead to the metal box to ground it If skipping this step leave the green clip unattached Note that significant line frequency intererence 50 Hz or 60 Hz is expected if no grounded enclosure is used 3 Connect the MONITOR output to Channel 2 of the oscilloscope using a BNC cable 4 Using the GAIN knob select 10 nA V if using a 10 MO resis tor select 1 A V 5 Set the function generator to output a sine wave 1 0 V pp at 10 Hz 6 Press the OUTPUT Enable button to turn on the current out put Verify tha
27. ese event flags are all sticky bits that are set by the corresponding events and cleared only by reading or with the CLS command Reading a single bit with the ESR query clears only Bit Weight Bit Flag 1 0 OPC 2 1 undef 0 4 2 QYE 8 3 DDE 16 4 EXE 32 5 CME 64 6 undef 0 128 7 undef 0 OPC OYE DDE Operation Complete Set by the OPC command Query Error Indicates data in the output queue has been lost Device Dependent Error Indicates an internal command queue overflow CS580 Voltage Controlled Current Source SRS 3 18 Remote Operation EXE Execution Error Indicates the error in a command that was successfully parsed Out of range parameters are an example CME Command Frror Indicates a command parser detected error 3 5 3 1 Standard event status enable ESE The ESE acts as a bitwise AND with the ESR register to produce the single bit ESB message in the Status Byte Register SB The register can be set and queried with the ESE command At power on this register is cleared SRS CS580 Voltage Controlled Current Source Appendix A Fuse Installation and ac Line Select The CS580 operates from 100 V 120 V 220 V 230 V or 240 V nominal ac power having a line frequency of 50 Hz or 60 Hz and accommo dates both North American single fuse or metric dual fuse operation This appendix provides detailed instructions for modifying the input voltage se
28. esistor at the point where the black lead was just removed Both meters should now display 1 V 11 Press the OUTPUT Enable button to turn off the output For the preceding example the CS580 was used as a DC current source and the default settings for gain and compliance voltage were left unchanged The 3 terminals of the triax connection referred to as center inner shield and outer shield are accessed from the red black and green alligator clips respectively The center conductor red clip is always the current output of the instrument and is the high impedance node where current is sourced sinked by the CS580 to the user s load The outer shield green clip is always tied to chassis ground The inner shield black clip is configured by the SHIELD and ISO LATION sections of the front panel When SHIELD is configured as Return the inner shield is electrically connected to the return node of the current source when so configured this node may be used to complete the current source circuit When SHIELD is configured as Guard the inner shield is driven by the voltage buffer to track the voltage of the center conductor In this mode the inner shield acts as a driven guard to reduce leakage and potentially increase AC bandwidth but it cannot be used to carry the return current of the source When ISOLATION is configured as Float the entire current source circuit is disconnected from chassis ground In this configuration
29. eturned bit s of the ESR register are cleared ESR 64 CS580 Voltage Controlled Current Source f SRS Remote Operation ESE i Example Standard event status enable Set query the Standard Event Status Enable Register bit i to j ESE 6 1 ESE 64 CLS Example Clear status CLS immediately clears the ESR register CLS LEXE Example Last execution error Query the last execution error code A query of LEXE always clears the error code so a subsequent LEXE will return 0 Valid codes are Value Definition No execution error since last LEXE Illegal value Wrong token Invalid bit Queue full Not compatible CURR 12 0 LEXE LEXE 1 0 Jg AeA U A A C The error 1 Illegal value is because the parameter value 12 9 is too large for CURR The second read of LEXE returns 0 ASRS CS580 Voltage Controlled Current Source 3 4 Commands LCME Example Last command error Query the last command error code A query of LCME always clears the error code so a subsequent LCME will return 0 Valid codes are Value Definition SCAND TF WNF CO PPR PY PWN FR C IDN LCME 4 No execution error since last LCME Illegal command Undefined command Illegal query Illegal set Missing parameter s Extra parameter s Null parameter s Parameter buffer overflow Bad floating point Bad integer Bad integer token Bad t
30. ion lost 2 12 2 6 3 Calibrationlost 2 12 deg Operation 2 1 Navigating the front panel The front panel of the CS580 is organized into distinct functional sections A picture of the entire front panel is in Figure 2 1 below del CS5 L SETTINGS 100 wo S DU yA 10 i 50 ev DC current Compliance voltage Compliance limit On TEN Figure 2 1 The CS580 front panel 2 1 1 Gain Use the knob to select the voltage to current gain of the CS580 from 1 nA V to 50mA V This also sets the range for the dc current setting to 2 V times the gain For instance when set to 10 uA V gain the range of dc current is 20 uA Note that Gain cannot be changed when the output is on and the analog input is also on SRS CS580 Voltage Controlled Current Source 2 1 Navigating the front panel 2 3 2 1 2 Settings 2 1 3 Adjust 2 1 4 Configuration 2 1 5 Input 2 1 6 Speed This block displays either the dc current setting or the compliance voltage setting Pressing the knob toggles between the two displays which are indicated below the numeric display The knob is used to both toggle between dc current and compliance voltage and adjusting either of those two settings The current focus of the knob is indicated by the two small indicator LEDs just below the numeric display briefly press and release the knob to toggle between DC current a
31. lection and replacing the line fuse A 1 Power Entry module The line cord receptacle power switch fuse holder and line voltage selector are all part of the power entry module located on the rear panel of the CS580 Detailed instructions for changing the line voltage selection and fuse replacement follow Fuse Holder Cover hinged Voltage Selector Indicator Pin Figure A 1 The CS580 Power Entry assembly A 2 ac voltage selector The CS580 line voltage selection is indicated by the white pin visible at the right hand edge of the power entry module In the image below the line voltage selection is showing 120 V Note that the 230 V position is appropriate for both 220 V and 230V nominal ac line voltages A 2 Fuse and ac Line The following steps describe how to change the line voltage selection 1 Disconnect and remove the power cord 2 Open the fuse cover see instructions below for fuse installa tion for detailed illustrations 3 Pull the voltage selector card straight out of the housing using small needle nose plyers to grip the plastic indicator pin body 4 Orient the selector card so that the desired line voltage is read able at the bottom Sez E E o No e N e n N s w amp Te eE e IN o A je Baap A O 100V 120
32. nd Compliance voltage Turning the knob modifies the displayed value To quickly set the pa rameter to zero press and hold the knob inwards for several seconds until the display shows zero This section of the front panel indicates the present configuration of the instrument The upper pair of LED indicators within the diagram show the state of the SHIELD mode as either Guard or Return The lower pair of LED indicators show the ISOLATION mode as either Float the upper yellow indicator or Ground the lower green indicator The CPU indicator shows when the internal digital circuitry of the CS580 is active in response to a user command The user analog input voltage is applied to the BNC in the INPUT section Note that the analog input voltage is only applied when the On indicator is lit Pressing the Enable button toggles the On state The Overload indicator reflects both the maximum input range of the analog input 2 V as well as any dc current being added by the CS580 Pressing the Speed button toggles between Fast and Slow mode When Slow is selected a 470 pF capacitor is added to the output node CS580 Voltage Controlled Current Source SRS 2 4 Operation 2 1 7 Shield 2 1 8 Isolation 2 1 9 Monitor 2 1 10 Output 2 2 Power on keys 2 2 1 Power on reset 2 2 2 Power on identify Pressing the Shield button toggles between Guard and Return modes This controls the inner shield of the triax co
33. nnector selecting between the driven guard and the current source return The Shield setting cannot be changed when the output is On Pressing the Ground button toggles between Float and Ground and effectively isolates the current source circuit from chassis ground The Ground setting cannot be changed when the output is On The banana jacks of the MONITOR block provide a convenient way to monitor the operating voltage of the current source output Note that the black Return jack may be needed to complete the current circuit when operating in Float Guard mode Also note that the red Guard jack has a 5kQ output impedance which can limit the bandwidth when monitoring an ac signal through long cables The triaxial connector of the OUTPUT block is the main connection to the current source The source output is toggled On and off by pressing the OUTPUT Enable button If the operating voltage reaches the compliance voltage limit the Compliance limit indicator lights There are two special button operations available to users while turn ing on power to the CS580 Pressing and holding the Input Enable button while turning on power will restore the default configuration of the CS580 This is equivalent to the remote RST command Pressing and holding the Speed button while turning on power will cause the instrument s serial number and firmware revision number to be shown on the numberic display ASRS CS580 Voltage Con
34. oken value Bad hex block Unknown token The error 4 Illegal set is due to the missing CS580 Voltage Controlled Current Source SRS 3 16 Remote Operation 3 5 Status model status registers The CS580 status registers follow the hierarchical IEEE 488 2 format A block diagram of the status register array is given in Figure 3 1 Standard Event Status CME Command error sts 4 4 DDE Device error BE 3 QYE Query error aga mE OPC Operation complete o 0 Status Byte Figure 3 1 Status Model for the CS580 Voltage Controlled Current Source There are three categories of registers in the status model of the current source Event Registers Enable Registers Status Byte These read only registers record the occurrence of defined events within the current source If the event occurs the corre sponding bit is set to 1 Upon querying an event register any set bits within it are cleared These are sometimes known as sticky bits since once set a bit can only be cleared by reading its value Event register names end with SR or EV These read write registers define a bitwise mask for their cor responding event register If any bit position is set in an event register while the same bit position is also set in the enable register then the corresponding summary bit message is set in the Status Byte Enable register names end with SE or EN This read only register
35. ot have any user serviceable parts inside Refer service to a qualified technician Do not install substitute parts or perform any unauthorized modi fications to this instrument Contact the factory for instructions on how to return the instrument for authorized service and adjustment vi General Information Symbols you may Find on SRS Products Alternating current Caution risk of electric shock Frame or chassis terminal Caution refer to accompanying documents Earth ground terminal SRS CS580 Voltage Controlled Current Source General Information vii Notation A WARNING N CAUTION The following notation will be used throughout this manual A warning means that injury or death is possible if the instructions are not obeyed A caution means that damage to the instrument or other equipment is possible Typesetting conventions used in this manual are e Front panel buttons are set as Button e Front panel knobs are set as e Front panel indicators are set as Overload e Remote command names are set as IDN e Literal text other than command names is set as OFF Remote command examples will all be set in monospaced font In these examples data sent by the host computer to the CS580 are set as straight teletype font while responses received by the host computer from the CS580 are set as slanted teletype font CS580 Voltage Controlled Current Source SRS viii General Information S
36. pecifications Output Input All performance specifications after 1 hour warm up at 23 C 2 C ambient Parameter Specification Output current 0 to 110 mA in 9 ranges Compliance voltage 0 to 50 V bipolar Compliance voltage error 0 5 50 mV max overshoot 1 5 V DC output resistance 10 Q 1nA V gain Output capacitance lt 12 pF filter off lt 500 pF filter on Guard output 50 V to 50 V 5kQ internal resistance Output power 5 V A four quadrant sourcing sinking Total harmonic distortion 0 05 typ Output connectors 3 lug Triax for current output Banana jacks for voltage monitoring Common mode voltage 250 Vrms max DC to 60 Hz Common mode isolation gt 1 GQ lt 1nF Parameter Specification Input range 2V to 42V Input impedance 100kO Input connector BNC Analog input performance Max Bandwidth Gain Gain output 0 Q load typ accuracy 1nA V 22nA 5kHz 1 2 10nA V 22nA 10 kHz 1 2 100nA V 220nA 20kHz 1 2 luA V 2 2 UA 75kHz 0 5 96 IU HA 22uA 150kHz 0 5 100 A V 220uA 150kHz 0 5 1mA V 22mA 150kHz 0 5 10mA V 22mA 200kHz 0 5 50mA V 110mA 150kHz 1 ASRS CS580 Voltage Controlled Current Source General Information ix DC current performance Parameter Specification Gain drift 200 ppm C Offset 3 mV
37. receipt of the RST command GAIN G1MA e INPT ON e RESP FAST e SHLD RETURN e SOL FLOAT e SOUT OFF e VOLT 10 0 e CURR 0 0 e ALRM ON The same reset to default configuration can also be performed by holding the INPUT Enable button depressed while switching on power ASRS CS580 Voltage Controlled Current Source 3 4 Commands OVLD Example Overload Reads the current value of the signal overload status Returns an integer between 1 and 3 if an overload is detected or 0 if there is no overload The response integer is binary weighted based on the two 2 separate signal stages that can generate an overload detect Value Definition 1 Compliance limit reached 2 Analog input overload If Compliance limit is lit then OVLD returns 1 If the INPUT Over load indicator is lit then OVLD returns 2 If both Overload and Compliance limit are simultaneously lit then OVLD returns 3 If neither are lit then OVLD returns 9 If TOKN ON mode is set then the OVLD query responds either NONE 0 OUTPUT 1 INPUT 2 or INP amp OUT 3 OVLD 0 STB 1 Example Status byte Reads the Status Byte register bit STB 0 SRE i UT Example Service request enable Set query the Service Request Enable register bit i to j SRE 0 1 ESR i Example Standard event status Reads the Standard Event Status Register bit i Upon executing ESR the r
38. represents the top of the status model and is populated with summary bit messages and interface condition bits Enabled bits within the Status Byte generate the remote Request Service event At power on all status registers are cleared 3 5 1 Status byte SB The Status Byte is the top level summary of the CS580 status model When enabled by the Service Request Enable register a bit set in the Status Byte causes the MSS Master Summary Status bit to be set ASRS CS580 Voltage Controlled Current Source 3 5 Status model Weight Bit Flag 1 0 undef 0 2 1 undef 0 4 2 undef 0 8 3 undef 0 16 4 undef 0 32 5 ESB 64 6 MSS 128 7 undef 0 ESB Event Status Bit Indicates whether one or more of the enabled MSS events in the Standard Event Status Register is true Master Summary Status Indicates whether one or more of the enabled status messages in the Status Byte register is true This register is read with the STB query 3 5 2 Service request enable SRE Each bit in the SRE corresponds one to one with a bit in the SB regis ter and acts as a bitwise AND of the SB flags to generate MSS Bit 6 of the SRE is undefined setting it has no effect and reading it always returns 0 This register is set and queried with the SRE command At power on this register is cleared 3 5 3 Standard event status ESR The Standard Event Status Register consists of 8 event flags Th
39. s generically shown as Z in the command descrip tions can be specified either as a keyword or as an integer value Command descriptions list the valid keyword options with each keyword followed by its corresponding integer value For example to set the reference mode to internal the following two commands are equivalent RESP SLow or RESP 1 For queries that return token values the return format keyword or integer is specified with the TOKN command ASRS CS580 Voltage Controlled Current Source 3 4 Commands 3 4 2 Notation The following table summarizes the notation used in the command descriptions Symbol Definition f g Floating point value i j Unsigned integer Z Literal token Required for queries illegal for set commands var Parameter always required var Required parameter for set commands illegal for queries var Optional parameter for both set and query forms 3 4 3 Examples Each command is provided with a simple example illustrating its usage In these examples all data sent by the host computer to the CS580 are setas straight teletype font while responses received by the host computer from the CS580 are set as slanted teletype font The usage examples vary with respect to set query optional parame ters and token formats These examples are not exhaustive and are intended to provide a convenient starting point for user program ming CS580 Voltage Controlled Current So
40. showed the active voltage limiting of the CS580 ASRS CS580 Voltage Controlled Current Source 2 Operation This chapter provides a basic overview of the CS580 Voltage Con trolled Current Source In This Chapter 2 1 Navigating the front panel 2 2 2 bL Gain soa eod vp Hime ER 2 2 Z2 Settings AA AAA A i 2 3 21 3 E A A p PS 2 3 2 1 4 Configuration i cx ace C BS Ree aus 2 3 2l a 61 51 ge alte ae esos 2 3 2 0 Speed ssp rn shot mms ee ee a de 2 3 21 7 Shields 4 ti t EE 2 4 2 1 8 Isolation e 3 seo doen b cea 2 4 2 19 MORON ako a VERSES EA 2 4 2 1 10 Output a REA Se E dus 2 4 2 2 Power on keys ook poe ope Ra ce 2 4 2 2 1 Power on reset 2 4 222 Power on identify 2 4 2 3 Introduction to the instrument 2 5 2 3 1 Clock stopping architecture 2 5 2 4 Instrument overview oo 2 5 2 4 1 Input section yp an ae Ge 2 5 242 DC current ii we es a 2 6 2 4 3 Compliance voltage 2 7 2 4 4 Current source 2 7 245 Speed setig i ca sud We BE te sus 2 8 24 6 Guard buffer 2 8 24 7 Isolation llle 2 9 2 4 8 UU de iesu ter EU 2 9 2 5 Configurations and grounding 2 9 25 1 Floating configurations aa 2 9 2 5 2 Grounded configurations 2 10 2 6 Errormessages o o o 2 12 2 6 1 Firmware corruption ccoo 49 ws 2 12 2 6 2 Configurat
41. t Channel 2 on the oscilloscope shows a 10 V pp signal corresponding to 10nA pp 1 0 uA pp for 10 MO 7 Press the ADJUST knob to select Compliance voltage and then turn ADJUST to select 2 0 V Verify that Channel 2 on the oscilloscope is now showing clipping at 2 V CS580 Voltage Controlled Current Source f SRS 1 8 Getting Started 1 5 2 Discussion When connected to a high impedance load attaching additional test leads such as a 10 MQ scope probe is not practical if operating with a 1 GQ load such a probe would shunt away 99 of the output current leaving the intended load starved of current This is the essential purpose of the MONITOR output Internal to the CS580 an electrometer grade voltage buffer provides a unity gain copy of the voltage across the external load Note that the monitor output has 5 kQ output source impedance which can limit the monitor bandwidth when driving significant cable lengths This monitor output can then be used for external measurements such as with an oscilloscope without affecting the current flowing through the load Do note however that the black banana terminal of the MONITOR output is electrically tied to the return node of the current source When using the CS580 in floating mode making a grounded connec tion to the MONITOR output such as through an oscilloscope will effectively ground the current source as well Finally adjusting the compliance voltage limit
42. tory for recalibration ASRS CS580 Voltage Controlled Current Source 3 Remote Operation In This Chapter This chapter describes operating the CS580 over the remote inter faces 3 1 3 2 3 3 3 4 3 5 Index of commands 3 2 Alphabetic list of commands 3 3 Introduction 432529 RR a Oe eee RR 3 5 3 83 1 Interface configuration 3 5 3 9 27 Buesa Wee ac Set Oh ate s 3 5 Commands eri g ah ale Be eo E e 3 6 3 4 1 Command syntax se eid vo Re sad 3 6 3 4 2 Notation 0 000000 2 ae 3 7 34 39 Examples irp uote Bae s USA E DER EG 3 7 3 4 4 Configuration commands 3 8 3 4 5 Setting commands 3 11 3 4 6 Setup commands aaaea aa 3 11 3 4 7 Interface commands 3 11 3 4 8 Status commands 3 12 Status model ep RT eee a 3 16 Sod Status Byte DB 22 ee Fede gone sient 3 16 3 5 2 Service request enable SRE 3 17 3 5 8 Standard event status ESR 3 17 3 2 Remote Operation 3 1 Index of commands Symbol Definition fg Floating point value i j Unsigned integer Z Literal token Required for queries illegal for set commands var Parameter always required var Required parameter for set commands illegal for queries var Optional parameter for both set and query forms Configuration GAIN z 3 8 Gain INPT z 3 8 Analog input RESP z
43. trolled Current Source 23 Introduction to the instrument 2 5 2 3 2 3 1 2 4 2 4 1 Introduction to the instrument The CS580 Voltage Controlled Current Source is a benchtop instru ment for sourcing and sinking low noise currents from femtoamps to milliamps The key feature of the CS580 is the analog voltage in put which lets researchers use their existing ac instruments such as lock in amplifiers to control the output current The output triaxial connector can be configured for either return current or driven guard operation and the entire current source may be floated or grounded by user command Configuration of the instrument is controlled either from the front panel buttons or from your computer using one of the remote inter faces Commands are processed by an internal microcontroller that halts its internal clock when idle preventing unwanted digital noise Clock stopping architecture This clock stopping architecture first introduced by SRS in the SR560 Voltage Preamplifier eliminates the inconvenience and relia bility issues associated with mechanical panel controls and makes full remote operation of the CS580 possible Whenever the microcon troller becomes active the CPU activity indicator illuminates clearly showing when the digital clock is running This occurs in response to front panel button presses or remote computer commands The numeric display on the CS580 is exclusively for setting either
44. urce SRS 3 8 Remote Operation 3 4 4 Configuration commands GAIN z Example Gain Set query the voltage to current gain setting to z Allowable val ues for Z are z Value Gain z Value Gain GinA 0 1nA V G100uA 5 100 uA V G10nA 1 10nA V GImA 6 1mA V G100nA 2 100nA V G10mA 7 10mA V GluA 3 1pA V G50mA 8 50mA V G10uA 4 10 uA V The GAIN command is equivalent to turning the GAIN knob Note that the DC current range is always 2 V times the gain for example when GAIN G10uA the DC current range is 20 uA Note that the GAIN command may not be set while the analog input and the output are both enabled GAIN G10UA INPT z Example Analog input Set query the analog input mode to Z OFF 0 ON 1 The analog input BNC is controlled through the INPT command or equivalently by pressing the INPUT Enable button Note that the analog input is controlled independently of the current source output SOUT INPT ON RESP 2 Example Speed Set query the current source filter response speed to Z FAST 9 SLOW 1 When switched to RESP SLOW a 470 pf capacitor is connected from the current source output to the current return limiting the output bandwidth in a load impedance dependent way The RESP com mand is equivalent to pressing the Speed button RESP 0 ASRS CS580 Voltage Controlled Current Source 3 4 Commands SH
45. urposes driving the guarded inner shield when configured for Shield Guard mode and also to support voltage measurements without loading the external circuit When the CS580 is configured for SHIELD Guard the inner shield conductor of the triax is connected to the buffer output This config uration bootstraps the inner shield to track the center conductor potential minimizing the effect of leakage current through the ca ble as well as charging currents for cable capacitance Operating in SHIELD Guard mode can provide a significant improvement in settling time effective bandwidth and dc leakage current losses but in cases with very long cables or excessive capacitance instability or even oscillation of the buffer amplifier is possible When the CS580 is configured for SHIELD Return the inner shield conductor of the triax is connected to the current source return node For some experiments this provides a convenient return path for current from the external load back to the instrument Also in cases where the Guard configuration showed instability or oscillation op erating in SHIELD Return avoids these difficulties Regardless of the SHIELD configuration the electrometer grade unity gain voltage buffer is always connected to the red banana jack in the MONITOR section This terminal is intended to provide the user a convenient point to measure the operating voltage without loading the external circuit ASRS CS580 Voltag
46. urrent in this configuration may flow back to the CS580 through the outer shield of the triax connector while the inner shield serves as a driven guard for the experiment CS580 Voltage Controlled Current Source SRS 2 12 Operation 2 6 Error messages When the CS580 first turns on it performs a number of internal self checks before beginning operation If one of these fails the following error messages may appear on the numeric display 2 6 1 Firmware corruption 2 6 2 Configuration lost 2 6 3 Calibration lost If the non volatile program memory becomes corrupted the CS580 may display the message Err FL indicating the flash memory is invalid This failure is unlikely but the instrument will not operate in this mode and must be returned to the factory for service If the memory recording the last configuration of the CS580 is de termined to be corrupted upon power up the message Err CF is displayed This message may be cleared by pressing any button after which the instrument will begin operating from the default configuration as though RTS had run If the memory recording the factory calibration values becomes corr puted the CS580 the message Err CL will be displayed This mes sage can be cleared by pressing any button after which the nominal calibration values will be reloaded In this case the instrument will operate but will not perform to specification Return the instrument to the fac
47. utput node of the CS580 The compliance can be set between 0 and 50 V either from the front panel or remotely For situations where there is a maximum safe operating voltage for the external load the user should adjust the compliance voltage to a value smaller than the safe maximum The user should also estimate the voltage needed for the desired current being sent to the load The compliance voltage should be adjusted to a value greater than this to avoid limiting the output due to compliance voltage For example if an experiment needs to source 2 uA into a 10MO load the minimum compliance voltage setting needed to not clip the currentis V IxR 22uAX10 MO 20 V If the maximum safe voltage for the load is 30 V then a reasonable setting for the compliance voltage limit might be 25 V Note that if the compliance voltage limit is set below 20 V clipping will occur For instance if the compliance voltage is set to 10 V then the output current will limit to 1 uA 2 4 3 1 Compliance voltage accuracy and overshoot Users should understand the accuracy limits of the compliance volt age circuitry For dc or slowly varying signals the complaince volt age error can be up to 50mV 0 5 of the compliance setting In the previous example where the compliance voltage was set to 25 V the actual limiting voltage would be 25 V 175 mV The situation is different for rapidly changing signals such as large amplitude square waves In such cases it is
48. wer entry module and into a grounded wall outlet ASRS CS580 Voltage Controlled Current Source 13 DC current and monitor output 1 3 4 Connect a BNC cable from function generator output to the CS580 front panel INPUT BNC Tee the connection to also go to Channel 1 of the oscilloscope Plug the triax to alligator cable into the front panel OUTPUT triax connector Switch on the AC power while holding the INPUT Enable button depressed Once the CS580 indicators all light you may release Enable This will perform the power on reset After several seconds the display will show DEf Cfg and then 0 0000 Connect the triax red alligator clip to one end of the 1 KQ resis tor Connect the triax black alligator clip to the other end of the 1kQ resistor Place the resistor on a non conductive surface and ensure that the triax green alligator clip is not touching any conductor Connect the banana to BNC adaptor into the MONITOR jack on the front panel Ensure the ground side of the adaptor is plugged into the black receptacle Allow the unit to warm up for 1 hour for full specified perfor mance Warm up is not needed to test basic functionality 1 3 DC current and monitor output 1 3 1 Procedure This first test demonstrates the basic connections of the CS580 and will exercise the internal DC current generator Press the INPUT Enable button to turn off the INPUT On indi

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