Lake Shore Cryotronics 121 Page 25 User Manual Download | Manualshive

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15

Chapter 3: Operation

3.1 General

This chapter provides instructions for the general operating features of
the Model 121 current source. Computer interface 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

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Summary of Contents for 121

Page 1: ...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 5 P N ...

Page 2: ...hore s plant 5 This limited warranty does not apply to defects in the Product resultingfrom a improper or inadequate installation unless OT 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...

Page 3: ...gical 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 prohibi...

Page 4: ...y 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 Archival copies are st...

Page 5: ...e 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 radiosand cell phones Exposure to RF interference greater than thatfound in a typical laboratory environment may disturb the sensitive measurement circuitry of the instru ment Pay...

Page 6: ......

Page 7: ...t 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 Generators 13 2 7 5 Lowering Measurement Noise 14 2 8 Rack Mounting 14 Chapter 3 Operation 3 1 General 1...

Page 8: ...stalling 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 23 4 2 3 3 2 Extract the driver 23 4 2 3 3 3 Manually install the driver 24 4 2 4 Communication 26 4 2 4 1 Character Format 26 4 2 4 2 Message Strings 26 4 2 5 Message Flow Control 27 4 3 Command Summary 29 4 3 1 Interface Commands 30 Chapter 5 Options and Accessorie...

Page 9: ...ke 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...

Page 10: ...iv ...

Page 11: ...ble 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...

Page 12: ...hermal 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 a voltmeter readout D Magnetic sensor calibration and measurement D Semiconductor...

Page 13: ...y 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 0 01 change in output for 5 change in the DC input voltage Load regulation 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 300 ms for full scale change in current 100 ms...

Page 14: ...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 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...

Page 15: ...h an environment constitutes a definite safety hazard Keep Away from Live Circuits Operating personnel must not remove instrument covers 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 I...

Page 16: ...TION 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...

Page 17: ...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 Keepall 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 acc...

Page 18: ...ion 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 r...

Page 19: ...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 suppl...

Page 20: ...ut 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 conne...

Page 21: ...iven assuming 3 m 10 ft of sensor cable Longer cables 30 m 100 ft or more can be used but environment conditions 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 throug...

Page 22: ...pplicable 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 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 a...

Page 23: ...ive 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...

Page 24: ...de 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 ins...

Page 25: ...ch 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...

Page 26: ...ts 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 current 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...

Page 27: ...inum 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 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 ou...

Page 28: ...ory so when the current is enabled the instrument will go to this new range When reaching 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 ...

Page 29: ... 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 Co...

Page 30: ...s 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 Unlocked or Locked Default Unlocked Interface Command LOCK ...

Page 31: ...f 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 ...

Page 32: ...eges 4 2 3 1 Installing the Driver From Windows Update in Windows 7 and Vista 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 Hardware ...

Page 33: ...ting 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...

Page 34: ...ually install the driver using Windows 7 Vista and XP To install the driver you must be logged into a user account that has administrator privileges For Windows 7 and Vista 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 ...

Page 35: ...pear 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 Device Manager b Click View and ensure the Devices by Type check box is selected c In the m...

Page 36: ...ing 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 charac...

Page 37: ... 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 progra...

Page 38: ...he 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 ...

Page 39: ... Brief description of command Command name Form of the command input Syntax of user parameter input see key below Definition of first parameter Input Format nn range 0 100 nA Current Range Command 1 300 nA 2 1 μA 3 3 μA 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...

Page 40: ...nge 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 identify queries s n String of alphanumeric characters with length n Send these strings using surrounding quotes Quotes enable characters such as commas and spaces ...

Page 41: ...T display contrast term Format nn display brightness 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 command for description Returned display brightness term COMP Compl...

Page 42: ...ks 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 state term IPOL Polarity Command Input IPOL state term Format n state 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 Inpu...

Page 43: ...ned state term PWUPENBL Power Up Enable Input PWUPENBL state term Format state 0 disabled 1 enabled Remarks Specifies whether the output remains on or shuts off after power cycle RANGE Current Range Command Input RANGE range term Format nn range 0 100 nA 1 300 nA 2 1 µA 3 3 µA 4 10 µA 5 30 µA 6 100 µA 7 300 µA 8 1 mA 9 3 mA 10 10 mA 11 30 mA 12 100 mA 13 User current Remarks Allows the user to cha...

Page 44: ...le 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 user current value Remarks User current will be returned in engineering nota tion with three significant digits SETSAVE Power on Setup State Input SETSAVE Remarks The command saves the ...

Page 45: ...ist 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 ...

Page 46: ...36 CHAPTER 5 Options and Accessories ...

Page 47: ...Windows the device status can be checked using Device Manager by right clicking Lake Shore Model 121 Current Source under Ports COM 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 LPT 4 Check...

Page 48: ...oft Windows the device status can be checked using Device Manager by right clicking Lake Shore Model 121 Current Source under Ports COM 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 a...

Page 49: ...btained 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...

Page 50: ...E 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 ...

Page 51: ...re 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...

Page 52: ...request form at http www lakeshore com Service Pro vide 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 durin...

Page 53: ...cessary for all returned equipment It must be clearly indicated on both the shipping carton s and any correspondence 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 La...

Page 54: ...44 CHAPTER 6 Service ...

Page 55: ...es 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 and 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...

Page 56: ... 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 re...

Page 57: ...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 ar...

Page 58: ...as 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 ...

Page 59: ...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 ...

Page 60: ...50 APPENDICES B 1 1 CE Declaration for Model 121 ...

Page 61: ...51 B 1 2 CE Declaration for the Power Supply Part Number 109 132 ...

Page 62: ...52 APPENDICES ...

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