Model 121 user manual - Lake Shore Cryotronics, Inc.
Contents
1. 7 2 2 Inspecting and Unpacking 7 2 3 Rear Panel Definition 8 2 4 Power Input Connector 9 2 5 External Power Supply 9 2 6 Cable Clamp 10 2 7 Current Source Output 10 2 7 1 Current Source Output Connector 10 2 7 2 Sensor Lead Cable 11 2 7 3 Grounding and Shielding Sensor Leads 11 2 7 4 Sensor Polarity 12 2 7 4 1 Resistive Sensors 12 2 7 4 2 Diode Sensors 12 2 7 4 3 Hall Generators2. 23 4 2 3 3 2 Extract the driver 24 4 2 3 3 3 Manually install the driver 24 4 2 3 4 Installing the USB Driver from the Included CD 26 4 2 4 Communication 27 4 2 4 1 Character Format 27 4 2 4 2 Message Strings 27 4 2 5 Message Flow Control 28 4 3 Command Summary 29 4 3 1 Interface Commands 30 Chapter 5 Options and Accessories 5 1 General 35 5 2 Models 35 5 3 Accessories 35 Chapter 6 Service 6 1 General
3. 13 2 7 5 Lowering Measurement Noise 14 2 8 Rack Mounting 14 Chapter 3 Operation 3 1 General 15 3 2 Instrument Power 15 3 3 Front Panel Description 16 3 3 1 Keypad Definitions 16 3 3 2 Display Annunciators 16 3 4 Display Brightness 17 3 5 Output Current Setup 17 ii 3 5 1 Enable Disable 17 3 5 2 Range Change 17 3 5 3 Polarity Change 18 3
4. 37 6 2 USB Troubleshooting 37 6 2 1 New Installation 37 6 2 2 Existing Installation No Longer Working 38 6 2 3 Intermittent Lockups 38 iii 6 3 Factory Reset 39 6 4 Product Information 39 6 5 Error Messages 39 6 6 Calibration Procedure 39 6 7 Rear Panel Connector Definition 40 6 8 Firmware Updates 41 6 8 1 Updating the Firmware 41 6 8 2 Record of Updates Made to the Firmware 41 6 9 Technical Inquiries
5. 42 6 9 1 Contacting Lake Shore 42 6 9 2 Return of Equipment 42 6 9 3 RMA Valid Period 43 6 9 4 Shipping Charges 43 6 9 5 Restocking Fee 43 Appendix A Handling Liquid Helium and Nitrogen A 1 General 45 A 2 Properties 45 A 3 Handling Cryogenic Storage Dewars 46 A 4 Liquid Helium and Nitrogen Safety Precautions 46 A 5 Recommended First Aid 48 Appendix B Regulatory Declarations B 1 General 49 B 1 1 CE Declaration for Model 121 50
6. show extracted files when complete checkbox and click Extract For Windows XP 1 Right click on the file and click extract all 2 The Extraction wizard will appear Click Next 3 It is recommended the default folder is not changed Take note of this folder location and click Next 4 An Extraction complete message is displayed Click to clear the show extracted files checkbox and click Finish 4 2 3 3 3 Manually install the driver Manually installing drivers differ between versions of Windows The fol lowing sections describe how to manually install the driver using Win dows XP Windows Vista Windows 7 and Windows 8 To install the driver you must be logged into a user account that has administrator privileges For Windows Vista Windows 7 and Windows 8 1 Connect the USB cable from the Model 121 to the computer 2 Turn on the Model 121 3 If the Found New Hardware wizard appears click ask me again later 4 Open Device Manager Use this procedure to open Device Manager a Click the Windows Start button and type Device Manager in the Start Search box b Click on the Device Manager link in the Search Results Under Programs c If User Account Control is enabled click Continue on the User Account Control prompt 25 5 Click View and ensure the Devices by Type check box is selected 6 In the main window of Device Manager locate Other Devices in the list of device types In
7. B 1 2 CE Declaration for the Power Supply Part Number 109 132 51 B 1 3 RoHS Declaration for the Power Supply Part Number 109 132 52 iv 1 Chapter 1 Introduction 1 1 Overview The Model 121 programmable DC current source is a precision instru ment suitable for bench top use or panel mounted operation in labs test facilities and manufacturing environments It provides a low noise highly stable source of current up to 100 mA with convenient manual selection through 13 pre set output levels each representing a ten fold change in power when attached to a resistive load A user setting allows the current output to be defined anywhere within the operating range of the unit from 100 nA to 100 mA Programmable operation is also possible via the instrument s USB com puter interface through which the Model 121 can be commanded to output any desired current at any time Thus application specific test currents can be driven from an external PC The instrument operates at 5 VDC and power is supplied by the external AC wall mount supply provided with the standard Model 121 The sup ply will automatically conform to any AC line voltage ranging from 100 VAC to 240 VAC 50 or 60 Hz D 7 decades of output current selectable in 13 steps D Programmable current output 100 nA to
8. and manufacture of most electronics To qualify for the CE Mark the Model 121 meets or exceeds the requirements of the European EMC Directive 89 336 EEC as a CLASS A prod uct A Class A product is allowed to radiate more RF than a Class B product and must include the following warning WARNING This is a Class A product In a domestic environment this product may cause radio interference in which case the user may be required to take adequate measures The instrument was tested under normal operating conditions with sensor and interface cables attached If the installation and operating instructions in the User s Manual are fol lowed there should be no degradation in EMC performance This instrument is not intended for use in close proximity to RF Transmitters such as two way radios and cell phones Exposure to RF interference greater than that found in a typical laboratory environment may disturb the sensitive measurement circuitry of the instru ment Pay special attention to instrument cabling Improperly installed cabling may defeat even the best EMC protection For the best performance from any precision instrument follow the grounding and shielding instructions in the User s Manual In addition the installer of the Model 121 should consider the following D Shield measurement and computer interface cables D Leave no unused or unterminated cables attached to the instrument D Make cable runs as short and direct as possible Highe
9. 0 45 kg 1 lb Approval CE Mark 1 4 Safety Summary and Symbols Observe these general safety precautions during all phases of instru ment operation service and repair Failure to comply with these precau tions or with specific warnings elsewhere in this manual violates safety standards of design manufacture and intended instrument use Lake Shore Cryotronics Inc assumes no liability for Customer failure to com ply with these requirements The Model 121 protects the operator and surrounding area from electric shock or burn mechanical hazards excessive temperature and spread of fire from the instrument Environmental conditions outside of the conditions below may pose a hazard to the operator and surrounding area 5 D Indoor use D Altitude to 2000 m D Temperature for safe operation 5 C to 40 C D Maximum relative humidity 80 for temperature up to 31 C decreasing linearly to 50 at 40 C D Power supply voltage fluctuations not to exceed 10 of the nomi nal voltage D Overvoltage category II D Pollution degree 2 The power supply included with the Model 121 meets or exceeds the European Union Standard EN 60950 Do Not Operate in an Explosive Atmosphere Do not operate the instrument in the presence of flammable gases or fumes Operation of any electrical instrument in such an environment constitutes a definite safety hazard Keep Away from Live Circuits Operating personnel must not remove instrument cove
10. 100 mA D Low noise output D Large 3 digit LED display D Simple user interface D Current reversal feature D USB interface enables integration with automated test systems D DIN panel mountable package D Detachable output terminal block D CE mark certification 2 CHAPTER 1 Introduction 1 2 Applications The Model 121 current source is ideally suited for testing measuring and operating resistive and semiconductor devices such as D Lake Shore Cernox temperature sensors D Other resistance temperature detectors RTDs such as platinum sensors D Diode temperature sensors including Lake Shore DT 670 s D LED devices D Hall sensors used for magnetic field measurement An accurate stable source of current is key to ensuring consistent opera tion of these devices where the voltage drop across the device can be dependent upon temperature magnetic field and other parameters The instrument s wide output range is of great value when used with RTD type sensors whose resistance can vary with temperature by as much as 6 orders of magnitude The current reversal feature enables compensation for thermal EMF important for accurately measuring resistors at very low excitation levels Example applications include D Basic device QC good bad verification D LED brightness testing constant device current D Temperature sensor calibration determine resistance at fixed cali bration points D Temperature measurement using
11. 5 4 User Current 19 3 5 5 Power Up Enable 19 3 6 Power Up State 19 3 7 Locking and Unlocking the Keypad 20 Chapter 4 Computer Interface Operation 4 1 General 21 4 2 USB Interface 21 4 2 1 Physical Connection 21 4 2 2 Hardware Support 21 4 2 3 Installing the USB Driver 22 4 2 3 1 Installing the Driver From Windows Update in Windows Vista Windows 7 and Windows 8 22 4 2 3 2 Installing the Driver From Windows Update in Windows XP 23 4 2 3 3 Installing the Driver from the Web 23 4 2 3 3 1 Download the driver
12. be transmitting at a given time or guarantee timing between messages All of this is the responsi bility of the user program When issuing commands the user program alone should D Properly format and transmit the command including the termina tor as one string D Guarantee that no other communication is started for 50 ms after the last character is transmitted D Not initiate communication more than 20 times per second 29 When issuing queries or queries and commands together the user pro gram should D Properly format and transmit the query including the terminator as one string D Prepare to receive a response immediately D Receive the entire response from the instrument including the ter minator D Guarantee that no other communication is started during the response or for 50 ms after it completes D Not initiate communication more than 20 times per second Failure to follow these simple rules will result in inability to establish communication with the instrument or intermittent failures in commu nication 4 3 Command Summary This section provides a listing of the interface commands A summary of all the commands is provided in TABLE 4 2 All the commands are detailed in section 4 3 1 and are presented in alphabetical order FIGURE 4 1 Sample command format FIGURE 4 2 Sample query format RANGE lt range gt term RANGE Brief description of command Command name Form of the command input Syntax of user pa
13. command for description Returned lt display brightness gt term COMP Compliance Limit Query Input COMP term Format n Returned lt compliance status gt 0 normal operation 1 in compliance limit Remarks Returns the voltage compliance limit status of the current source output 32 CHAPTER 4 Computer Interface Operation DFLT Factory Defaults Command Input DFLT 99 term Remarks Sets all configuration values to factory defaults and resets the instrument The 99 is included to prevent accidentally setting the unit to defaults IENBL Current Enable Command Input IENBL lt state gt term Format n lt state gt 0 disabled 1 enabled Remarks Allows for the current source output to be disabled or enabled IENBL Current Enable Query Input IENBL term Format n refer to command for description Returned lt state gt term IPOL Polarity Command Input IPOL lt state gt term Format n lt state gt 0 positive 1 negative Remarks Allows for the polarity of the current to be changed This does not affect the polarity of the user current setting IPOL Polarity Query Input IPOL term Format n refer to command for description Returned lt state gt term Remarks Only valid for the fixed ranges not the user current setting 33 LOCK Front Panel Keypad Lock Command Input LOCK lt state gt term Format n lt state gt 0 unlock 1 lock Remarks Allows for the user to lock or u
14. many instances this will be between Network adapters and Ports COM amp LPT If the Other Devices item is not already expanded click the icon Lake Shore Model 121 should appear indented underneath Other Devices If it is not displayed as Lake Shore Model 121 it might be displayed as USB Device If nei ther are displayed click Action and then Scan for hardware changes which may open the Found New Hardware wizard automatically If the Found New Hardware wizard opens click Cancel 7 Right click on Lake Shore Model 121 and click Update Driver Soft ware 8 Click Browse my computer for driver software 9 Click Browse and select the location of the extracted driver 10 Ensure the Include subfolders check box is selected and click Next 11 When the driver finishes installing a confirmation message stating Windows has successfully updated your driver software should appear 12 Click Close to complete the installation For Windows XP 1 Connect the USB cable from the Model 121 to the computer 2 Turn on the Model 121 3 The Found New Hardware wizard should appear If the Found New Hardware wizard does not appear the following procedure can be used to open the Hardware Update wizard which can be used instead a Open Device Manager Use this procedure to open the Device Manager D Right click on My Computer and then click Properties This will open the System Properties dialog D Click the Hardware tab and then click D
15. the United States National Institute of Standards and Technology NIST for merly known as the National Bureau of Standards NBS FIRMWARE LIMITATIONS Lake Shore has worked to ensure that the Model 121 firmware is as free of errors as possi ble and that the results you obtain from the instrument are accurate and reliable How ever as with any computer based software the possibility of errors exists In any important research as when using any laboratory equipment results should be carefully examined and rechecked before final conclusions are drawn Neither Lake Shore nor anyone else involved in the creation or production of this firmware can pay for loss of time inconvenience loss of use of the product or property damage caused by this product or its failure to work or any other incidental or consequential damages Use of our product implies that you understand the Lake Shore license agreement and statement of limited warranty FIRMWARE LICENSE AGREEMENT The firmware in this instrument is protected by United States copyright law and interna tional treaty provisions To maintain the warranty the code contained in the firmware must not be modified Any changes made to the code is at the user s risk Lake Shore will assume no responsibility for damage or errors incurred as result of any changes made to the firmware Under the terms of this agreement you may only use the Model 121 firmware as physically installed in the instrument Arc
16. the informa tion presented in this chapter Factory trained service personnel should be consulted if the instrument requires repair 6 2 USB Troubleshooting This section provides USB interface troubleshooting for issues that arise with new installations existing installations and intermittent lockups 6 2 1 New Installation 1 Check that the instruments interface is set to USB 2 Check that the USB driver is installed properly and that the device is functioning In Microsoft Windows the device status can be checked using Device Manager by right clicking Lake Shore Model 121 Current Source under Ports COM amp LPT or Other Devices and then clicking Properties Refer to section 4 2 3 for details on install ing the USB driver 3 Check that the correct com port is being used In Microsoft Win dows the com port number can be checked using Device Manager under Ports COM amp LPT 4 Check that the correct settings are being used for communication Refer to section 4 2 3 for details on installing the USB driver 5 Check cable connections and length 6 Send the message terminator 7 Send the entire message string at one time including the terminator Many terminal emulation programs do not 8 Send only one simple command at a time until communication is established 9 Be sure to spell commands correctly and use proper syntax 38 CHAPTER 6 Service 6 2 2 Existing Installation No Longer Working 1 Power the instru
17. the physical connections of a USB This programming interface requires a certain configuration to communicate properly with the Model 121 The proper configuration parameters are listed in TABLE 4 1 22 CHAPTER 4 Computer Interface Operation The USB hardware connection uses the full speed 12 000 000 bits sec profile of the USB 2 0 standard however since the interface uses a vir tual serial com port at a fixed data rate the data throughput is still lim ited to a baud rate of 57 600 bits sec 4 2 3 Installing the USB Driver The Model 121 USB driver has been made available through Windows Update This is the recommended method for installing the driver as it will ensure that you always have the latest version of the driver installed If you are unable to install the driver from Windows Update refer to section 4 2 3 3 to install the driver from the web or from the disc pro vided with the Model 121 These procedures assume that you are logged into a user account that has administrator privileges 4 2 3 1 Installing the Driver From Windows Update in Windows Vista Windows 7 and Windows 8 1 Connect the USB cable from the Model 121 to the computer 2 Turn on the Model 121 3 When the Found New Hardware wizard appears select Locate and install driver software recommended 4 If User Account Control UAC is enabled a UAC dialog box may appear asking if you want to continue Click Continue 5 The Found New Hardwa
18. the user cur rent range USER will display once before displaying OFF Menu Navigation Range 100 nA 300 nA Default 100 nA Interface Command RANGE 3 5 3 Polarity Change The Model 121 allows for the user to switch the polarity of the current by pressing This key will switch the polarity of the output current for any of the fixed ranges and user current The key works inde pendently for the fixed ranges and user current range Pressing in a fixed range will change the polarity of all fixed ranges but not the user current Pressing in the user current range will only change the polar ity of the user current The instrument will immediately change the polarity of the current upon receiving a key press Menu Navigation Polarity Positive or Negative Default Positive Interface Command IPOL 19 3 5 4 User Current Through the computer interface the Model 121 can be programmed to a current that is between the fixed ranges This user current is between 100 nA and 100 mA with three digits of resolution Refer to Chapter 4 to configure the user current setting When the user range is selected pressing will change the polarity of the user current but will not affect the fixed ranges Refer to section 3 5 3 for more information The user range is selected by pressing when in the 100 mA range The dis play will then flash USER once then it will flash the user current value twice before setting the
19. to reduce measurement noise The suggestions fall into two cate gories 1 do not let noise from the outside enter into the measurement and 2 let the instrument isolation and other hardware features work to their best advantage Here are some further suggestions D Do not connect sensor leads to earth ground or chassis D Use twisted shielded cable outside the cooling system D Attach the chassis to the cable shield and to earth ground if possible D Use twisted wire inside the cooling system D Consider ground strapping the instrument chassis to other instru ments or computers D Tie all ground points at one common point to avoid ground loops D For demanding applications the display can be turned off 2 8 Rack Mounting The Model 121 can be easily mounted using the panel mount brackets included The Model 121 fits in a 91 44 mm 3 6 1 7 in cutout To panel mount the instrument unplug the unit and use a 1 bg inch hex wrench to remove the two set screws holding the brackets in place Remove the two panel mount brackets by sliding them towards the rear of the unit Place the unit into the panel cutout Slide the two panel mount brackets back into the case of the instrument Reinstall the two set screws and tighten them until the instrument is secure FIGURE 2 7 Rack mounting 15 Chapter 3 Operation 3 1 General This chapter provides instructions for the general operating features of the Model 121 current source Computer int
20. well ventilated If inhaled remove to fresh air If not breathing give artificial respiration If breathing is difficult give oxygen Get medical help Liquid helium and liquid nitrogen can cause severe frostbite to the eyes or skin DO NOT touch frosted pipes or valves In case of frostbite consult a physi cian at once If a physician is not readily available warm the affected areas with water that is near body temperature The two most important safety aspects to consider when handling LHe and LN2 are adequate ventilation and eye and skin protection Although helium and nitrogen gases are non toxic they are dangerous in that they replace the air in a normal breathing atmosphere Liquid products are of an even greater threat since a small amount of liquid evaporates to cre ate a large amount of gas Therefore it is imperative that cryogenic Dew ars be stored and the MTD system be operated in open and well ventilated areas Persons transferring LHe and LN2 should make every effort to protect eyes and skin from accidental contact with liquid or the cold gas issuing from it Protect your eyes with full face shield or chemical splash gog gles Safety glasses even with side shields are not adequate Always wear special cryogenic gloves Tempshield Cryo Gloves or equivalent when handling anything that is or may have been in contact with the liquid or cold gas or with cold pipes or equipment Long sleeve shirts and cuffless trouser
21. RE 6 3 Power supply connector Pin Description Inner conductor 5 V Outer conductor Ground TABLE 6 5 Power supply pin and connector details 42 CHAPTER 6 Service 6 9 Technical Inquiries Refer to the following sections when contacting Lake Shore for applica tion assistance or product service Questions regarding product applica tions price availability and shipments should be directed to sales Questions regarding instrument calibration or repair should be directed to instrument service Do not return a product to Lake Shore without a Return Material Authorization RMA number section 6 9 2 6 9 1 Contacting Lake Shore The Lake Shore Service Department is staffed Monday through Friday between the hours of 8 00 AM and 5 00 PM EST excluding holidays and company shut down days Contact Lake Shore Service through any of the means listed below How ever the most direct and efficient means of contacting is to complete the online service request form at http www lakeshore com sup serf html Provide a detailed description of the problem and the required contact information You will receive a response within 24 hours or the next business day in the event of weekends or holidays If you wish to contact Service or Sales by mail or telephone use the following 6 9 2 Return of Equipment The temperature controller is packaged to protect it during shipment The user should retain any shipping carton s in which equipment is or
22. User s Manual Model 121 Programmable DC Current Source Methods and apparatus disclosed and described herein have been developed solely on company funds of Lake Shore Cryotronics Inc No government or other contractual support or relationship whatsoever has existed which in any way affects or mitigates proprietary rights of Lake Shore Cryotronics Inc in these developments Methods and apparatus dis closed herein may be subject to U S Patents existing or applied for Lake Shore Cryotronics Inc reserves the right to add improve modify or withdraw functions design modifica tions or products at any time without notice Lake Shore shall not be liable for errors con tained herein or for incidental or consequential damages in connection with furnishing performance or use of this material Rev 1 3 P N 119 061 22 April 2015 Lake Shore Cryotronics Inc 575 McCorkle Blvd Westerville Ohio 43082 8888 USA sales lakeshore com service lakeshore com www lakeshore com Fax 614 891 1392 B Telephone 614 891 2243 LIMITED WARRANTY STATEMENT WARRANTY PERIOD THREE 3 YEARS 1 Lake Shore warrants that products manufactured by Lake Shore the Product will be free from defects in materials and workmanship for three years from the date of Pur chaser s physical receipt of the Product the Warranty Period If Lake Shore receives notice of any such defects during the Warranty Period and the defective Product is shipped freight prepa
23. a voltmeter readout D Magnetic sensor calibration and measurement D Semiconductor device measurements IV curves for diodes transis tors etc D Circuit prototyping fixed current source D Small scale electro chemical applications Whether operating over a wide range of environmental conditions establishing precise sensor calibrations or simply testing devices for conformance the Model 121 provides a convenient and reliable alterna tive to simple voltage based circuits and a very affordable alternative to more expensive multi function current sources It can be readily inte grated into automated test systems using its built in USB computer interface and offers a highly readable simple to use operator display 3 1 3 Model 121 Specifications 1 3 1 Output Type Bipolar DC current source Current ranges 13 fixed ranges of 100 nA 300 nA 1 A 3 A 10 A 30 A 100 A 300 A 1 mA 3 mA 10 mA 30 mA 100 mA and a user pro grammable range Accuracy 0 05 on 10 A range 0 5 on 100 nA and 300 nA ranges 0 1 on all other ranges Compliance voltage 11 V up to 30 mA 10 V up to 100 mA AC current ripple lt 0 1 on 100 nA and 300 nA ranges lt 0 01 on all other ranges in a properly shielded system Current ripple frequency Dominated by line frequency and its harmonics Temperature coefficient 0 03 of range C for the 100 nA range 0 01 of range C for all other ranges Line regulation lt 0 01 change in o
24. as flood fire wind or earthquake or h damage during shipment other than original shipment to you if shipped through a Lake Shore carrier 6 This limited warranty does not cover a regularly scheduled or ordinary and expected recalibrations of the Product b accessories to the Product such as probe tips and cables holders wire grease varnish feed throughs etc c consumables used in conjunction with the Product such as probe tips and cables probe holders sample tails rods and hold ers ceramic putty for mounting samples Hall sample cards Hall sample enclosures etc or d non Lake Shore branded Products that are integrated with the Product 7 To the extent allowed by applicable law this limited warranty is the only warranty applicable to the Product and replaces all other warranties or conditions express or implied including but not limited to the implied warranties or conditions of merchantabi lity and fitness for a particular purpose Specifically except as provided herein LakeShore undertakes no responsibility that the products will be fit for any particular pur pose for which you may be buying the Products Any implied warranty is limited in duration to the warranty period No oral or written information or advice given by the Company its Agents or Employees shall create a warranty or in any way increase the scope of this lim ited warranty Some countries states or provinces do not allow limitations on a
25. d isolated the gases will liquefy when prop erly cooled A quick comparison between LHe and LN2 is provided in TABLE A 1 Property Liquid Helium Liquid Nitrogen Boiling Point at 1 atm 4 2 K 77 K Thermal Conductivity Gas w cm K 0 083 0 013 Latent Heat of Vaporization Btu L 2 4 152 Liquid Density lb L 0 275 0 78 TABLE A 1 Comparison of liquid helium and liquid nitrogen 46 APPENDICES A 3 Handling Cryogenic Storage Dewars Cryogenic containers Dewars must be operated in accordance with the manufacturer instructions Safety instructions will also be posted on the side of each Dewar Cryogenic Dewars must be kept in a well ventilated place where they are protected from the weather and away from any sources of heat A typical cryogenic Dewar is shown in FIGURE A 1 A 4 Liquid Helium and Nitrogen Safety Precautions Transferring LHe and LN2 and operation of the storage Dewar controls should be in accordance with the manufacturer supplier s instructions During this transfer it is important that all safety precautions written on the storage Dewar and recommended by the manufacturer be followed FIGURE A 1 Typical cryogenic storage Dewar 47 Liquid helium and liquid nitrogen are potential asphyxiants and can cause rapid suffocation without warning Store and use in area with adequate ventila tion DO NOT vent container in confined spaces DO NOT enter confined spaces where gas may be present unless area has been
26. ead this entire chapter before installing the instrument and powering it on to ensure the best possible performance and maintain operator safety For instrument operating instructions refer to Chapter 3 For computer interface installation and operation refer to Chapter 4 2 2 Inspecting and Unpacking Inspect shipping containers for external damage before opening them Photograph any container that has significant damage before opening it Inspect all items for both visible and hidden damage that may have occurred during shipment If there is visible damage to the contents of the container contact the shipping company and Lake Shore immedi ately preferably within five days of receipt of goods for instructions on how to file a proper insurance claim Lake Shore products are insured against damage during shipment but a timely claim must be filed before Lake Shore will take further action Procedures vary slightly with ship ping companies Keep all damaged shipping materials and contents until instructed to either return or discard them Open the shipping container and keep the container and shipping mate rials until all contents have been accounted for Check off each item on the packing list as it is unpacked Instruments themselves may be shipped as several parts The items included with the Model 121 are listed below Contact Lake Shore immediately if there is a shortage of parts or accessories Lake Shore is not responsible for any missing i
27. ediately 49 Appendix B Regulatory Declarations B 1 General Declarations in this appendix apply to the Lake Shore Cryotronics Model 121 programmable DC current source beginning with serial number 121000A and subsequent as well as its power supply Paragraph B1 1 refers to the CE declaration for the Model 121 alone Paragraphs B1 2 through B1 5 refer to the CE and RoHS declarations respectively for the unit s power supply The declarations included are as follows D CE declaration for the Model 121 D CE declaration for the power supply P N 109 132 D RoHS declaration for the power supply P N 109 132 50 APPENDICES B 1 1 CE Declaration for Model 121 51 B 1 2 CE Declaration for the Power Supply Part Number 109 132 52 APPENDICES B 1 3 RoHS Declaration for the Power Supply Part Number 109 132
28. emory has been reset Release the two keys and the display will return to normal opera tion 6 4 Product Information Product information for your instrument is found by pressing and for three seconds This will display the firmware version Any future key you press will exit this menu 6 5 Error Messages The following are error messages that may be displayed by the Model 121 during operation 6 6 Calibration Procedure Instrument calibration can be obtained through Lake Shore Service Refer to section 6 9 for technical inquiries and contact information Instrument configuration Default Current polarity Positive Current enable Off Pre set current range 100 nA User current 100 nA Display brightness 8 Keypad lock status Unlock Power up enable Off Available only in firmware release 1 3 or later TABLE 6 1 Factory default settings Message Description Err1 There is a hardware problem in the instrument memory This error is not correctable by the user and the factory should be consulted Refer to section 6 9 Err2 There is a soft error in the instrument memory This error can be corrected by reinitializ ing memory Reinitializing memory sets the instrument to defaults Refer to section 6 3 Err3 The calibration memory is either corrupt or is in the default uncalibrated state To con tinue with the instrument in an uncalibrated state press and simultaneously TABLE 6 2 Error message
29. erface instructions are in Chapter 4 3 2 Instrument Power The Model 121 is powered on by plugging in the power supply There is no power switch on the instrument When the Model 121 is powered on with no errors present 121 will illuminate for a few seconds to indi cate instrument initialization The instrument powers up in the power up state with the current disabled Refer to section 3 6 When the instru ment is powered on for the first time parameters are set to the factory defaults listed in TABLE 6 1 The instrument should be powered on for thirty minutes before using for rated specifications FIGURE 3 1 Model 121 front panel 16 CHAPTER 3 Operation 3 3 Front Panel Description The Model 121 has a 6 digit LED display capable of showing both numeric and character data In normal operation the display shows the output of the current source The four annunciators on the lower right hand side of the display indicate the units of the current and whether the instrument is detecting voltage compliance There are also four keys that allow for manually changing the range polarity or disabling the current source output 3 3 1 Keypad Definitions The keypad for the Model 121 consists of four keys as described in TABLE 3 1 3 3 2 Display Annunciators Display annunciators include symbols for units of current and voltage compliance Key Function Refer to section Allows the user to change the polarity of the output curren
30. evice Manager b Click View and ensure the Devices by Type check box is selected c In the main window of Device Manager locate the Ports COM amp LPT device type In many instances this will be between the Net work adapters and Processors items If the Ports COM amp LPT item is not already expanded click the icon Lake Shore Model 121 should appear indented underneath Ports COM amp LPT If it 26 CHAPTER 4 Computer Interface Operation is not displayed as Lake Shore Model 121 it might be displayed as USB Device If neither are displayed click Action and then select Scan for hardware changes which may open the Found New Hardware wizard automatically If the Found New Hard ware wizard opens continue to step 4 d Right click on Lake Shore Model 121 and click Update Driver 4 Select No not at this time and click Next 5 Select Search for the best driver in these locations click to clear the Search removable media floppy CD ROM check box and click the Include this location in the search check box 6 Click Browse and open the location of the extracted driver 7 Click Next 8 When the driver finishes installing a confirmation message stating The wizard has finished installing the software for Lake Shore Model 121 Current Source should appear Click Finish to complete the installation 4 2 3 4 Installing the USB Driver from the Included CD The Model 121 USB driver is available on the included CD The
31. following section describes the process of installing the driver from the CD To install the driver you must be logged into a user account that has admin istrator privileges For Windows Vista Windows 7 and Windows 8 1 Insert the CD into the computer 2 Follow steps 1 9 of the Windows Vista Windows 7 and Windows 8 procedure in section 4 2 3 3 3 3 Click Browse and select the drive containing the included CD 4 Ensure the Include subfolders check box is selected and click Next 5 When the driver finishes installing a confirmation message stating Windows has successfully updated your driver software will appear Click Close to complete the installation For Windows XP 1 Insert the CD into the computer 2 Connect the USB cable from the Model 121 to the computer 3 Turn on the Model 121 4 When the Found New Hardware wizard appears select No not at this time and click Next 5 Select Install the software automatically recommended and click Next 27 6 The Found New Hardware wizard should automatically search the CD and install the drivers 7 When the Found New Hardware Wizard finishes installing the driv ers a message stating the wizard has finished installing the soft ware for Lake Shore Model 121 Current Source should appear Click Finish to complete the installation 4 2 4 Communication Communicating via the USB interface is done using message strings The message strings should be carefu
32. hival copies are strictly forbidden You may not decompile disassemble or reverse engineer the firmware If you suspect there are problems with the firmware return the instrument to Lake Shore for repair under the terms of the Limited Warranty specified above Any unauthorized duplication or use of the Model 121 firmware in whole or in part in print or in any other storage and retrieval system is forbidden TRADEMARK ACKNOWLEDGMENT Many manufacturers and sellers claim designations used to distinguish their products as trademarks Where those designations appear in this manual and Lake Shore was aware of a trademark claim they appear with initial capital letters and the or symbol Cernox is a trademarks of Lake Shore Cryotronics Inc Microsoft Windows Excel Windows XP and Windows Vista are registered trademarks of Microsoft Corporation in the United States and other countries Copyright 2013 2015 by Lake Shore Cryotronics Inc All rights reserved No portion of this manual may be reproduced stored in a retrieval system or transmitted in any form or by any means electronic mechanical photocopying recording or otherwise without the express written permission of Lake Shore Electromagnetic Compatibility EMC for the Model 121 Current Source Electromagnetic Compatibility EMC of electronic equipment is a growing concern world wide Emissions of and immunity to electromagnetic interference is now part of the design
33. id back to Lake Shore Lake Shore will at its option either repair or replace the Product if it is so defective without charge for parts service labor or associated customary return shipping cost to the Purchaser Replacement for the Product may be by either new or equivalent in performance to new Replacement or repaired parts or a replaced Product will be warranted for only the unexpired portion of the original warranty or 90 days whichever is greater 2 Lake Shore warrants the Product only if the Product has been sold by an authorized Lake Shore employee sales representative dealer or an authorized Lake Shore original equip ment manufacturer OEM 3 The Product may contain remanufactured parts equivalent to new in performance or may have been subject to incidental use when it is originally sold to the Purchaser 4 The Warranty Period begins on the date the Product ships from Lake Shore s plant 5 This limited warranty does not apply to defects in the Product resulting from a improper or inadequate installation unless OT amp V services are performed by Lake Shore mainte nance repair or calibration b fuses software power surges lightning and non recharge able batteries c software interfacing parts or other supplies not furnished by Lake Shore d unauthorized modification or misuse e operation outside of the published specifica tions f improper site preparation or site maintenance g natural disasters such
34. ies affiliates or suppliers will be held liable for direct special incidental consequen tial or other damages including lost profit lost data or downtime costs arising out of the use inability to use or result of use of the product whether based in warranty contract tort or other legal theory regardless whether or not Lake Shore has been advised of the possibility of such damages Purchaser s use of the Product is entirely at Purchaser s risk Some countries states and provinces do not allow the exclusion of liability for incidental or consequential damages so the above limitation may not apply to you 12 This limited warranty gives you specific legal rights and you may also have other rights that vary within or between jurisdictions where the product is purchased and or used Some jurisdictions do not allow limitation in certain warranties and so the above limita tions or exclusions of some warranties stated above may not apply to you 13 Except to the extent allowed by applicable law the terms of this limited warranty state ment do not exclude restrict or modify the mandatory statutory rights applicable to the sale of the product to you CERTIFICATION Lake Shore certifies that this product has been inspected and tested in accordance with its published specifications and that this product met its published specifications at the time of shipment The accuracy and calibration of this product at the time of shipment are traceable to
35. ify queries s n String of alphanumeric characters with length n Send these strings using surrounding quotes Quotes enable characters such as commas and spaces to be used without the instrument interpreting them as delimiters nn String of number characters that may include a decimal point term Terminator characters lt gt Indicated a parameter field many are command specific lt state gt Parameter field with only On Off or Enable Disable states lt value gt Floating point values have varying resolution depending on the type of command or query issued TABLE 4 3 Interface commands key 31 IDN Identification Query Input IDN term Format s 4 s 8 s 7 n n lt manufacturer gt Manufacturer ID lt model gt Instrument model number lt instrument serial gt Instrument serial number lt firmware version gt Instrument firmware version Example LSCI MODEL121 1234567 1 0 RST Reset Instrument Command Input RST term Remarks Sets instrument parameters to power up settings BRIGT Display Brightness Command Input BRIGT lt display contrast gt term Format nn lt display brightness gt 0 15 Remarks Sets the display contrast for the front panel seven segment display A higher number makes the dis play brighter The default setting is 8 The display can be turned off with setting the brightness to 0 BRIGT Display Brightness Query Input BRIGT term Format nn refer to
36. iginally received in the event that any equipment needs to be returned Mailing address Lake Shore Cryotronics Instrument Service Department 575 McCorkle Blvd Westerville Ohio USA 43082 8888 E mail address sales lakeshore com service lakeshore com Sales Instrument Service Telephone 614 891 2244 614 891 2243 select the option for service Sales Instrument Service Fax 614 818 1600 614 818 1609 Sales Instrument Service Web service request http www lakeshore com sup serf html Instrument Service TABLE 8 6 Contact information 43 If the original packaging is not available a minimum of 76 2 mm 3 in of shock absorbent packing material should be placed snugly on all sides of the instrument in a sturdy corrugated cardboard box Please use reason able care when removing the temperature controller from its protective packaging and inspect it carefully for damage If it shows any sign of damage please file a claim with the carrier immediately Do not destroy the shipping container it will be required by the carrier as evidence to support claims Call Lake Shore for return and repair instructions All equipment returns must be approved by a member of the Lake Shore Service Department The service engineer will use the information pro vided in the service request form and will issue an RMA This number is necessary for all returned equipment It must be clearly indicated on both the shipping carton s and any correspo
37. instructions may not specify Four lead resistors can be more dependent on lead arrangement Follow any specified lead assignment for 4 lead resistors Mixing leads could give a reading that appears correct but is not the most accurate 2 7 4 2 Diode Sensors For diode sensors it is important to follow the instructions on polarity FIGURE 2 5 This is because diode sensors do not operate in the wrong polarity Diodes look like an open circuit to the instrument if the positive and negative pins are swapped FIGURE 2 5 DT 670 SD diode sensor leads Cathode Anode 13 2 7 4 3 Hall Generators With Hall generators the direction of the current and magnetic field are important to determining the sign of the Hall voltage As shown in FIG URE 2 6 the current enters the red lead with IC connected to the posi tive terminal of the current supply and the magnetic field direction B is into the page With this combination a positive Hall voltage will be gen erated at the VH lead Reversing either the current or the magnetic field will reverse the output voltage FIGURE 2 6 Hall generator leads High mobility III V semiconductor a Indium arsenide b Gallium arsenide VH Clear or yellow VH Blue Ic Green or black Ic Red Conventional current force on electron 14 CHAPTER 2 Installation 2 7 5 Lowering Measurement Noise Good instrument hardware setup technique is one of the least expensive ways
38. ishes installing the driver a confirmation message stating the wizard has finished installing the software for Lake Shore Model 121 Current Source will appear Click Finish to complete the installation 4 2 3 3 Installing the Driver from the Web The Model 121 USB driver is available on the Lake Shore website To install the driver it must be downloaded from the website and extracted Use the procedure in section 4 2 3 3 1 through section 4 2 3 3 3to down load extract and install the driver using Windows XP Windows Vista Windows 7 and Windows 8 4 2 3 3 1 Download the driver 1 Locate the Model 121 USB driver on the downloads page on the Lake Shore website 2 Right click on the USB driver download link and select save target link as 3 Save the driver to a convenient place and take note as to where the driver was downloaded 24 CHAPTER 4 Computer Interface Operation 4 2 3 3 2 Extract the driver The downloaded driver is in a ZIP compressed archive The driver must be extracted from this file Windows provides built in support for ZIP archives If this support is disabled a third party application such as WinZip or 7 Zip must be used For Windows Vista Windows 7 and Windows 8 1 Right click on the file and click Extract all 2 An Extract Compressed Zipped Folders dialog box will appear It is recommended the default folder is not changed Take note of this folder location 3 Click to clear the
39. ked or Locked Default Unlocked Interface Command LOCK 21 Chapter 4 Computer Interface Operation 4 1 General This chapter provides operational instructions for the computer inter face for the Lake Shore Model 121 Current Source The Model 121 pro vides a USB interface described in section 4 2 The Model 121 permits remote operation through the USB interface The interface commands are detailed in section 4 3 4 2 USB Interface The Model 121 USB interface provides a convenient way to connect to most modern computers The USB interface is implemented as a virtual serial com port connection This implementation provides a simple migration path for modifying existing RS 232 based remote interface software It also provides a simpler means of communicating than a standard USB implementation 4 2 1 Physical Connection The Model 121 has a B type USB connector on the rear panel This is the standard connector used on USB peripheral devices and it allows the common USB A type to B type cable to be used to connect the Model 121 to a host PC The pin assignments for A type and B type con nectors are shown in section 6 7 The maximum length of a USB cable as defined by the USB 2 0 standard is 5 m 16 4 ft This length can be extended using USB hubs every 5 m 16 4 ft up to 5 times for a maxi mum total length of 30 m 98 4 ft 4 2 2 Hardware Support The USB interface emulates an RS 232 serial port at a fixed 57 600 baud rate but with
40. lly formulated by the user program according to some simple rules to establish effective message flow con trol 4 2 4 1 Character Format A character is the smallest piece of information that can be transmitted by the interface Each character is ten bits long and contains data bits character timing bits and an error detection bit The instrument uses 7 bits for data in the American Standard Code for Information Interchange ASCII format One start bit and one stop bit are necessary to synchro nize consecutive characters Parity is a method of error detection One parity bit configured for odd parity is included in each character ASCII letter and number characters are used most often as character data Punctuation characters are used as delimiters to separate different commands or pieces of data A special ASCII character line feed LF 0AH is used to indicate the end of a message string This is called the message terminator 4 2 4 2 Message Strings A message string is a group of characters assembled to perform an inter face function There are three types of message strings commands que ries and responses The computer issues command and query strings through user programs the instrument issues responses Two or more command or query strings can be chained together in one communica tion but they must be separated by a semi colon The total communi cation string must not exceed 255 characters in length A command string is i
41. mand saves the present range polarity and user current value This saved state will be loaded on future power ups 35 Chapter 5 Options and Accessories 5 1 General This chapter provides information on the models options and accesso ries available for the Model 121 current source 5 2 Models The list of Model 121 model numbers is provided in TABLE 5 1 5 3 Accessories Accessories are devices that perform a secondary duty as an aid or refinement to the primary unit Refer to the Lake Shore Temperature Measurement and Control Catalog for details A list of accessories avail able for the Model 121 is provided in TABLE 5 2 Model Description of Models 121 Model 121 current source 121N Model 121 current source with no power supply TABLE 5 1 Model description Model Description of Accessories 109 132 5 V DC power supply 100 240 V 6 W power supply universal input changeable input plugs G 106 735 2 pin terminal block MAN 121 Model 121 current source manual CAL 121 CERT Instrument recalibration with certificate CAL 121 DATA Instrument recalibration with certificate and data Accessories included with a new Model 121 Accessories not included with a new Model 121N TABLE 5 2 Accessories 36 CHAPTER 5 Options and Accessories 37 Chapter 6 Service 6 1 General This chapter provides basic service information for the Model 121 cur rent source Customer service of the product is limited to
42. ment so it is off when not plugged in and on when plugged in Make sensor connections before applying power to the instrument The instrument requires 5 VDC at 250 mA The coaxial connector accepts a barrel plug 5 5 mm OD x 2 1 mm x 9 9 mm L Refer to FIGURE 2 2 for polarity To prevent electrical fire or shock hazards do not expose this instrument or its power supply to rain or excess moisture 2 5 External Power Supply The Model 121 comes with the universal input power supply Lake Shore P N 109 132 It can accept input voltages from 100 to 240 VAC 10 50 or 60 Hz For input power it has interchangeable plugs to accommo date power receptacles in different countries It has a barrel plug for the output It can output 5 VDC at 1 2 A The power supply is CE certified and meets or exceeds the following safety standards UL 60950 1 and EN 60950 To change plugs press the pad on the side of the plug pull off the old plug and snap in the new plug FIGURE 2 2 Power connector Pin Description Inner conductor 5 V Outer conductor2 Ground TABLE 2 1 Power input connector details 10 CHAPTER 2 Installation 2 6 Cable Clamp To avoid inadvertent disconnection from the power supply Lake Shore supplies a cable clamp that the user may attach to the cord and the instrument chassis It is a part of the accessories kit supplied with the unit To install the clamp remove the screw at the top left rear of the unit position the c
43. ment off then on again to see if it is a soft failure 2 Power the computer off then on again to see if communication port is locked up 3 Check all cable connections 4 Check that the com port assignment has not been changed In Mic rosoft Windows the com port number can be checked using Device Manager under Ports COM amp LPT 5 Check that the USB driver is installed properly and that the device is functioning In Microsoft Windows the device status can be checked using Device Manager by right clicking Lake Shore Model 121 Current Source under Ports COM amp LPT or Other Devices and then clicking Properties 6 2 3 Intermittent Lockups 1 Check cable connections and length 2 Increase the delay between all commands to 100 ms to make sure the instrument is not being overloaded 3 Ensure that the USB cable is not unplugged and that the Model 121 is not powered down while the com port is open The USB driver cre ates a com port when the USB connection is detected and removes the com port when the USB connection is no longer detected Removing the com port while in use by software can cause the soft ware to lock up or crash 39 6 3 Factory Reset It is sometimes necessary to reset instrument parameter values that are stored in nonvolatile memory Instrument calibration is not affected The factory defaults can be reset using by pressing and for three seconds All of the LED digits will illuminate when the m
44. n implied warranty so the above limitation or exclusion might not apply to you This warranty gives you specific legal rights and you might also have other rights that vary from country to country state to state or province to province 8 Further with regard to the United Nations Convention for International Sale of Goods CISC if CISG is found to apply in relation to this agreement which is specifically dis claimed by Lake Shore then this limited warranty excludes warranties that a the Product is fit for the purpose for which goods of the same description would ordinarily be used b the Product is fit for any particular purpose expressly or impliedly made known to Lake Shore at the time of the conclusion of the contract c the Product is contained or packaged in a manner usual for such goods or in a manner adequate to preserve and protect such goods where it is shipped by someone other than a carrier hired by Lake Shore 9 Lake Shore disclaims any warranties of technological value or of non infringement with respect to the Product and Lake Shore shall have no duty to defend indemnify or hold harmless you from and against any or all damages or costs incurred by you arising from the infringement of patents or trademarks or violation or copyrights by the Product 10 THIS WARRANTY IS NOT TRANSFERRABLE This warranty is not transferrable 11 Except to the extent prohibited by applicable law neither Lake Shore nor any of its sub sidiar
45. ndence relating to the ship ment Once the RMA has been approved you will receive appropriate documents and instructions for shipping the equipment to Lake Shore 6 9 3 RMA Valid Period RMAs are valid for 60 days from issuance however we suggest that equipment needing repair be shipped to Lake Shore within 30 days after the RMA has been issued You will be contacted if we do not receive the equipment within 30 days after the RMA is issued The RMA will be can celed if we do not receive the equipment after 60 days 6 9 4 Shipping Charges All shipments to Lake Shore are to be made prepaid by the customer Equipment serviced under warranty will be returned prepaid by Lake Shore Equipment serviced out of warranty will be returned FOB Lake Shore 6 9 5 Restocking Fee Lake Shore reserves the right to charge a restocking fee for items returned for exchange or reimbursement 44 CHAPTER 6 Service 45 Appendix A Handling Liquid Helium and Nitrogen A 1 General Use of liquid helium LHe and liquid nitrogen LN2 is often associated with the Model 121 current source Although not explosive there are a number of safety considerations to keep in mind in the handling of LHe and LN2 A 2 Properties LHe and LN2 are colorless odorless and tasteless gases Gaseous nitro gen makes up about 78 percent of the Earth s atmosphere while helium comprises only about 5 ppm Most helium is recovered from natural gas deposits Once collected an
46. nditions may degrade accuracy and noise spec ifications 2 7 3 Grounding and Shielding Sensor Leads The Model 121 does not provide ground referenced leads This means that I and I cannot be attached to ground in any configuration The standard power supply 109 132 does not carry earth ground through to chassis To meet the accuracy specifications at lower current levels the Model 121 must be in a properly shielded system Since the Model 121 is not connected to earth ground it is important to tie it to measurement common This connection can be made externally through the chassis FIGURE 2 4 Output connector Pin Symbol Description 1 I Current out 2 I Current return TABLE 2 2 Output current connector details 12 CHAPTER 2 Installation ground connection on the rear panel It is also advised to use sensor leads that are shielded and floating The shield should be tied to mea surement common When making any such connections it is important to avoid ground loops by connecting measurement commons at one point 2 7 4 Sensor Polarity Lake Shore sensors are shipped with instructions that indicate which sensor leads are which It is important to follow these instructions for plus and minus leads polarity as well as voltage and current when applicable 2 7 4 1 Resistive Sensors There are two styles of resistive sensor wirings 2 lead and 4 lead Two lead resistors can operate with any lead arrangement and the sensor
47. nlock the front panel keypad LOCK Front Panel Keypad Lock Query Input LOCK term Format n refer to command for description Returned lt state gt term PWUPENBL Power Up Enable Input PWUPENBL lt state gt term Format lt state gt 0 disabled 1 enabled Remarks Specifies whether the output remains on or shuts off after power cycle RANGE Current Range Command Input RANGE lt range gt term Format nn lt range gt 0 100 nA 1 300 nA 2 1 A 3 3 A 4 10 A 5 30 A 6 100 A 7 300 A 8 1 mA 9 3 mA 10 10 mA 11 30 mA 12 100 mA 13 User current Remarks Allows the user to change the current range Use the IPOL command to set the polarity 34 CHAPTER 4 Computer Interface Operation RANGE Current Range Query Input RANGE term Format nn Returned lt numeric key value gt term SETI Set User Current Command Input SETI Format nnne nn lt user current value gt Current value as a three digit number including a decimal place Remarks User current is settable between 100 nA and 100 mA The sign of the user current value determines the polarity of the output The IPOL command does not affect this setting SETI Set User Current Query Input SETI Format nnn nnne nn Returned lt user current value gt Remarks User current will be returned in engineering nota tion with three significant digits SETSAVE Power on Setup State Input SETSAVE Remarks The com
48. ord and clamp as shown in the photo and reinstall the screw 2 7 Current Source Output This section details how to connect various sensors to the Model 121 output Refer to section 3 5 to configure the outputs 2 7 1 Current Source Output Connector The output connector is a 2 pin terminal block The output connector pins are defined in FIGURE 2 4 and TABLE 2 2 One mating connector terminal block mate is included in the connector kit shipped with the instrument These are common connectors so additional mating con nectors can be purchased from local electronics suppliers They can also be ordered from Lake Shore as G 106 735 I cannot be connected to chassis ground FIGURE 2 3 Cable clamp for the Model 121 5V 11 2 7 2 Sensor Lead Cable The sensor lead cable used outside the cooling system can be much dif ferent from what is used inside Between the instrument and vacuum shroud heat leak is not a problem but errors from noise pick up need to be minimized Larger conductor 22 to 28 AWG stranded copper wire is recommended because it has low resistance yet remains flexible when several wires are bundled in a cable The arrangement of wires in a cable is also important For best results use twisted pair shielded cable This type of cable is available through local electronics suppliers Instrument specifications are given assuming 3 m 10 ft of sensor cable Longer cables 30 m 100 ft or more can be used but environment co
49. r radiated emissions are possible with long cables D Do not tightly bundle cables that carry different types of signals i Table of Contents Chapter 1 Introduction 1 1 Overview 1 1 2 Applications 2 1 3 Model 121 Specifications 3 1 3 1 Output 3 1 3 2 User setting 3 1 3 2 1 Programming 3 1 3 2 2 Front panel 4 1 3 2 3 Interface 4 1 3 3 General 4 1 4 Safety Summary and Symbols 4 Chapter 2 Installation 2 1 General
50. rameter input see key below Definition of first parameter Input Format nn lt range gt 0 100 nA Current Range Command 1 300 nA 2 1 A 3 3 A All ranges for this command are not included in this sample format RANGE term RANGE Brief description of query Query name Form of the query input Syntax of user parameter input see key below Definition of returned parameter Input Format Returned nn lt numeric key value gt term Current Range Query 30 CHAPTER 4 Computer Interface Operation 4 3 1 Interface Commands This section lists the interface commands in alphabetical order Command Function Page IDN Identification Query page 31 RST Reset Instrument Command page 31 BRIGT Display Contrast Command page 31 BRIGT Display Contrast Query page 31 COMP Compliance Limit Query page 31 DFLT Factory Defaults Command page 32 IENBL Current Enable Command page 32 IENBL Current Enable Query page 32 IPOL Polarity Command page 32 IPOL Polarity Query page 32 LOCK Front Panel Keypad Lock Command page 33 LOCK Front Panel Keypad Lock Query page 33 RANGE Output Range Command page 33 RANGE Output Range Query page 34 SETI User Current Setting Command page 34 SETI User Current Setting Query page 34 SETSAVE Power Up State page 34 TABLE 4 2 Command summary Begins common interface command Required to ident
51. re wizard should automatically connect to Windows Update and install the drivers If the Found New Hardware wizard is unable to con nect to Windows Update or find the drivers a mes sage to insert the disc that came with your Lake Shore Model 121 is displayed Click Cancel and refer to section 4 2 3 3 to install the driver from the web Baud rate 57 600 Data bits 7 Start bits 1 Stop bits 1 Parity Odd Flow control None Handshaking None TABLE 4 1 Host com port configuration 23 6 When the Found New Hardware wizard finishes installing the driver a confirmation message stating the software for this device has been successfully install will appear Click Close to complete the installation 4 2 3 2 Installing the Driver From Windows Update in Windows XP 1 Connect the USB cable from the Model 121 to the computer 2 Turn on the Model 121 3 When the Found New Hardware wizard appears select Yes this time only and click Next 4 Select Install the software automatically Recommended and click Next 5 The Found New Hardware wizard should automatically connect to Windows Update and install the drivers If the Found New Hardware wizard is unable to con nect to Windows Update or find the drivers a mes sage saying Cannot Install this Hardware is displayed Click Cancel and refer to section 4 2 3 3 to install the driver from the web 6 When the Found New Hardware wizard fin
52. rs Refer compo nent replacement and internal adjustments to qualified maintenance personnel Do not replace components with power cable connected To avoid injuries always disconnect power and discharge circuits before touching them Do Not Substitute Parts or Modify Instrument Do not install substitute parts or perform any unauthorized modification to the instrument Return the instrument to an authorized Lake Shore Cryotronics Inc representative for service and repair to ensure that safety features are maintained Cleaning Do not submerge instrument Clean only the exterior of the instrument with a damp cloth and mild detergent 6 CHAPTER 1 Introduction FIGURE 1 1 Safety symbols Direct current power line Equipment protected throughout by double insulation or reinforces insulation equivalent to Class II of IEC 536 see Annex H CAUTION High voltages danger of electric shock background color yellow symbol and outline black CAUTION or WARNING See instrument documentation background color yellow symbol and outline black Off supply On supply Frame or chassis terminal Protective conductor terminal Earth ground terminal 3 Three phase alternating current power line Alternating or direct current power line Alternating current power line 7 Chapter 2 Installation 2 1 General This chapter provides general installation instructions for the Model 121 current source Please r
53. s 40 CHAPTER 6 Service 6 7 Rear Panel Connector Definition The terminal block USB connector and power supply connector are defined in FIGURE 6 1 FIGURE 6 2 and FIGURE 6 3 FIGURE 6 1 Terminal block for output of current source Pin Description 1 Current 2 Current TABLE 6 3 Terminal block pin and connector details FIGURE 6 2 USB pin and connector details Pin Name Description 1 VCC 5 VDC 2 D Data 3 D Data 4 GND Ground TABLE 6 4 USB pin and connector details Pin 1 Pin 2 2 1 3 4 41 6 8 Firmware Updates This section provides instructions on updating your firmware It also pro vides a table of the updates that have been made thus far 6 8 1 Updating the Firmware Periodically Lake Shore provides updates to instrument firmware The files for these updates can be downloaded from our website To access the firmware updates follow this procedure 1 Go to 121 website page http www lakeshore com products DC Current Sources Model 121 DC Current Source Pages Over view aspx to download the instrument firmware 2 Enter your name and email address so that we can keep you updated on any new firmware for your instrument 3 Click the Go to the download bar and follow the prompts that are provided on the screen for you 6 8 2 Record of Updates Made to the Firmware 1 0 initial release 1 1 minor bug fixes 1 2 minor bug fixes 1 3 added Power Up Enable feature FIGU
54. s that are of sufficient length to prevent liquid from entering the shoes are recommended 48 APPENDICES A 5 Recommended First Aid Every site that stores and uses LHe and LN2 should have an appropriate Material Safety Data Sheet MSDS present The MSDS may be obtained from the manufacturer distributor The MSDS will specify the symptoms of overexposure and the first aid to be used A typical summary of these instructions is provided as follows If symptoms of asphyxia such as headache drowsiness dizziness exci tation excess salivation vomiting or unconsciousness are observed remove the victim to fresh air If breathing is difficult give oxygen If breathing has stopped give artificial respiration Call a physician imme diately If exposure to cryogenic liquids or cold gases occurs restore tissue to normal body temperature 98 6 F as rapidly as possible then protect the injured tissue from further damage and infection Call a physician immediately Rapid warming of the affected parts is best achieved by bathing it in warm water The water temperature should not exceed 105 F 40 C and under no circumstances should the frozen part be rubbed either before or after rewarming If the eyes are involved flush them thoroughly with warm water for at least 15 minutes In case of massive exposure remove clothing while showering with warm water The patient should not drink alcohol or smoke Keep warm and rest Call a physician imm
55. ssued by the computer and instructs the instru ment to perform a function or change a parameter setting The format is lt command mnemonic gt lt space gt lt parameter data gt lt terminators gt 28 CHAPTER 4 Computer Interface Operation Command mnemonics and parameter data necessary for each one is described in section 4 3 Terminators must be sent with every message string A query string is issued by the computer and instructs the instrument to send a response The query format is lt query mnemonic gt lt gt lt space gt lt parameter data gt lt terminators gt Query mnemonics are often the same as commands with the addition of a question mark Parameter data is often unnecessary when sending queries Query mnemonics and parameter data if necessary is described in section 4 3 Terminators must be sent with every message string The computer should expect a response very soon after a query is sent A response string is the instrument s response or answer to a query string The response can be a reading value status report or the present value of a parameter Response data formats are listed along with the associated queries in section 4 3 The response is sent as soon as possible after the instrument receives the query 4 2 5 Message Flow Control It is important to remember that the user program is in charge of the USB communication at all times The instrument cannot initiate com munication determine which device should
56. t section 3 5 3 Allows the user to increase the current range section 3 5 2 Allows the user to decrease the current range section 3 5 2 Allows the user to enable or disable the output current section 3 5 1 TABLE 3 1 Keypad definitions Annunciator Function mA Indicates that the output current is in units of mA A Indicates that the output current is in units of A nA Indicates that the output current is in units of nA CMP Indicates that the instrument is in voltage compliance TABLE 3 2 Display annunciators 17 3 4 Display Brightness The front panel 6 digit LED display brightness can be adjusted for opti mal viewing The default value 8 is recommended for most applications A setting of zero turns the display off which may reduce noise in sensi tive measurements This can only be configured through the computer interface Refer to Chapter 4 Menu Navigation Brightness 0 to 15 Default 8 Interface Command BRIGT 3 5 Output Current Setup This section explains how to configure the output current through the keypad Refer to Chapter 4 for information on the computer interface commands The Model 121 has been optimized to drive resistive sensors such as Cernox and Platinum Sensors diode sensors and Hall genera tors 3 5 1 Enable Disable The Model 121 allows the user to turn on or turn off the output current by pressing When this key is pressed the display will either read off for
57. tems if not notified within 60 days of shipment If the instrument must be returned for recalibration replacement or repair a Return Authorization RMA number must be obtained from a factory representative before it is returned Refer to section 6 9 3 for the Lake Shore RMA procedure Items Included with Model 121 current source D 1 Model 121 instrument D 1 Model 121 user s manual 8 CHAPTER 2 Installation D 1 terminal block mating connector 2 pin terminal block for current source output G 106 735 D 4 adhesive square rubber feet D 1 cable clamp for power supply cord D 1 universal input power supply interchangeable plug style 109 132 Not included with the 121N option 2 3 Rear Panel Definition This section provides a description of the Model 121 rear panel connec tions as shown in FIGURE 2 1 The rear panel consists of the current source output connector USB B type connector and power jack Instal lation information for each feature is outlined throughout the next few sections A summary of the connector pin outs is provided in section 6 7 Always remove power from the instrument before making any rear panel connections This is especially critical when making sensor to instrument connec tions FIGURE 2 1 Model 121 rear panel 9 2 4 Power Input Connector Power is supplied to the Model 121 through a coaxial connector located on the rear panel of the instrument There is no power switch on the instru
58. the disabled state or the display will show a numeric value for the enabled state The output current will always power on in the dis abled state In this state the instrument will not output any current Menu Navigation Output Enabled or Disabled Default Disabled Interface command IENBL 3 5 2 Range Change The Model 121 allows for the user to change ranges via the and keys The range can be changed to any of the 13 fixed ranges or the user current range using these keys The user current range can be accessed by pressing when in the 100 mA range The range does not wrap around For example when in the USER current range pressing will do nothing 18 CHAPTER 3 Operation When changing to a new range with the current enabled the new range will flash for 3 s before setting the new current For the user current range the instrument will flash USER once and then it will flash the actual value of the user current twice before changing the output cur rent This allows for the user to select a new range directly without applying intermediate ranges There is no wait time when making a range change through the computer interface Refer to Chapter 4 When changing to a new range with the current disabled the new range will display for 1 s before the display goes back to displaying OFF The new range will be stored in the memory so when the current is enabled the instrument will go to this new range When reaching
59. user current User Current 100 nA to 100 mA Default 100 nA Interface Command SETI 3 5 5 Power Up Enable The power up enable feature allows the user to choose whether or not the heater range is turned off each time the instrument power is cycled Setting the Power Up Enable parameter to Off ensures that the Heater Range is turned off on power up Setting it to On will return the heater range to its previous setting when power is restored Interface Command PWUPENBL 3 6 Power Up State The Model 121 can be programmed to power up in a user defined state called the power up state The power up state consists of three setup parameters range polarity and user current value To save the power up state configure the instrument with the desired settings then press and hold for 3 s To save it through the computer interface refer to chap ter 4 The power up state will match factory defaults after a factory reset 20 CHAPTER 3 Operation 3 7 Locking and Unlocking the Keypad The keypad lock feature prevents accidental changes to parameters When the keypad is locked the front panel is completely disabled To lock the instrument hold down for 3 s until the display reads LOC When the keypad is locked all future key presses will cause the dis play to read LOC for 1 s before returning to the previous display To unlock the keypad hold for 3 s until the display reads UnLOC Menu Navigation Keypad Unloc
60. utput for 5 change in the DC input voltage Load regulation lt 0 01 change in output current over the full scale range Stability 24 h 0 05 on 100 nA range 0 01 per day on all other fixed ranges Settling time lt 300 ms for full scale change in current lt 100 ms for 10 change in current Connector Detachable terminal block Maximum load 300 k 1 3 2 User setting 1 3 2 1 Programming Operation Output current settable via computer interface Resolution 3 significant digits Accuracy 0 5 for currents lt 300 nA 0 25 for all other currents Maximum current 100 mA Minimum current 100 nA 4 CHAPTER 1 Introduction 1 3 2 2 Front panel Display 6 digit LED display Display units mA A and nA Display update rate 2 rdg s Display anunciators mA A nA and compliance Keypad 4 full travel keys Keypad functions Range Up Range Down Current Polarity Enable Disable 1 3 2 3 Interface USB Function Emulates an RS 232 serial port Baud rate 57 600 Connector B type USB connector Reading rate Up to 10 rdg s Software support LabVIEW driver consult Lake Shore for availability 1 3 3 General Ambient temperature 15 C to 35 C at rated accuracy 5 C to 40 C at reduced accuracy Power requirement 5 VDC 5 at 250 mA barrel plug 5 5 mm OD 2 1 mm ID 9 9 mm L Size 96 mm W 48 mm H 166 mm D 3 8 in 1 9 in 6 5 in Mounting Panel mount into 91 mm W 44 mm H 3 6 in 1 7 in cutout Weight
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