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Model 480 - Lake Shore Cryotronics, Inc.

1. Alarm Relay Connection The Model 480 has alarm relays high middle and low The terminal block has normally open N O normally closed N C and common contacts COM for each relay The instrument provides no power through the relays they open and close as switches relative to their common contact The contacts are rated at 30 VDC at 2 A Refer to Paragraph 5 14 for alarm operation Analog Output Connections The Model 480 has two analog outputs corrected and monitor The terminal block has a signal and ground contact for each analog output The voltage outputs are short circuit protected but loads of 1 kQ or greater are required for specified operation The operation of the two outputs is different Refer to Paragraph 5 15 1 for corrected output and Paragraph 5 15 2 for monitor output operation External Reset Connections The Model 480 terminal block has connections for external reset With this feature a foot pedal or Programmable Logic Controller PLC can be used to start a new measurement cycle Refer to Paragraph 5 16 for external reset operation The External Reset is TTL compatible and a logic low will activate a reset The signal is internally pulled up to allow operation with a simple switch closure between Pins 12 and 13 Optional Input Connection The Model 480 terminal block has a connection for an optional logic input It is commonly used to monitor status of a thermostat or proximity switch The Model 480 monit
2. Automated Magnet Testing In automated testing time is money The Model 480 has many features to enhance throughput The instrument has a fast update rate and settling time It recovers quickly from reading reset to start a new reading cycle IEEE 488 and serial computer interfaces included with the Model 480 can be used to control most instrument functions Relays and analog outputs can be used for automation without a computer interface Magnetizing The magnetizing process places unique demands on all associated electronics The Model 480 responds with very fast peak capture that can keep up with the fastest magnetizing pulses Both a positive and negative peak can be captured from the same pulse The input of the Model 480 is protected against the high voltages at its input present during magnetizing Materials Analysis High resolution and low drift define the role of the fluxmeter in analytical measurement The high resolution of the Model 480 is reinforced by a low noise floor A configurable filter helps keep the readings quiet Automatic and manual drift adjustment modes help optimize the low drift characteristics of the integrators The IEEE 488 and serial computer interfaces included with the Model 480 allow automated data taking AC Magnetic Fields Sensing coils are sensitive to AC magnetic fields but many conventional integrating fluxmeters can not measure AC fields The Model 480 has an AC mode that enables it to measure fields ov
3. National Instruments GPIB Interface B Network adapters EE y Ports COM amp LPT Interface m Termination Methods m Timeouts Ml System devi Szene GPIBO 2 E Send El atendof write V2 10sec y GPIB Address MV Terminate Read on EOS SN Primar M Set EDI with EOS on Write 2 We sec y 12 y ge Properties Refresh R I 8 bit EOS Compare Secondary NONE y fio EOS Byte M Readdress Figure 6 2 DEV 12 Device Template Configuration 6 6 Computer Interface Operation Lake Shore Model 480 Fluxmeter User s Manual 6 1 4 2 Visual Basic IEEE 488 Interface Program Setup This IEEE 488 interface program works with Visual Basic 6 0 VB6 on an IBM PC or compatible with a Pentium class processor A Pentium 90 or higher is recommended running Windows 95 or better It assumes your IEEE 488 GPIB card is installed and operating correctly refer to Paragraph 6 1 4 1 Use the following procedure to develop the IEEE 488 Interface Program in Visual Basic 1 Start VB6 2 Choose Standard EXE and select Open 3 Resize form window to desired size 4 On the Project Menu select Add Module select the Existing tab then navigate to the location on your computer to add the following files Niglobal bas and Vbib 32 bas 5 Add controls to form a Add three Label controls to the form b Add two TextBox controls to the form c Add one CommandButton control to the form 6 On the View Menu select Properti
4. Remarks Returns the remote interface mode 0 local 1 remote 2 remote with local lockout OPTIN Query Optional Input Input OPTIN Returned 0 or 1 Format n term Remarks Queries the optional input on the rear panel 0 open or logic high 1 shorted or logic low PCTMUL Set Percent Multiplier Constant Input PCTMUL nnn nnnE nn Returned Nothing Remarks Sets the percent multiplier used to calculate units of percent Enter up to 6 digits and a decimal point in exponential form PCTMUL Query Percent Multiplier Constant Input PCTMUL Returned nnn nnnE nn Remarks Returns the percent multiplier constant used to calculate units of percent Returns up to 6 digits and a decimal point in exponential form PCTSET Initiate Set Percent Command Input PCTSET nnn nnnE nn Returned Nothing Remarks Recalculates a percent multiplier for the currently measured field The number part of the command is the desired reading value of the current field The coil must be in the field when the command is issued Example PCTSET 50 00 term Equates a display of 50 with the current reading Anytime the reading equals the current reading a value of 50 displays PEAK Configure Peak Hold Function Off On Input PEAK lt off on gt Returned Nothing Remarks Configures the peak hold function 0 Normal reading 1 Peak hold 6 32 Computer Interface Operation PEAK Input Returned Remarks PEAKM Input
5. 3 WDN Flux turns 7 T Flux density 4 V s Flux 8 G Flux density 9 Percent 10 Wb cm Magnetic Moment 11 A Magnetic Potential Query Display Units Type UNITS An integer from 1 to 11 Format n term Returns current units number Refer to UNITS command for unit number representations Computer Interface Operation Lake Shore Model 480 Fluxmeter User s Manual This Page Intentionally Left Blank 6 36 Computer Interface Operation Lake Shore Model 480 Fluxmeter User s Manual CHAPTER 7 ACCESSORIES COILS AND PROBES 7 0 GENERAL This chapter provides information the various accessories coils and probes available for the Lake Shore Model 480 Fluxmeter Accessories are described in Paragraph 7 1 field measuring probes in Paragraph 7 2 Helmholtz coils in Paragraph 7 3 and reference magnets in Paragraph 7 4 In many cases Users may mate existing coils and fixtures to the Model 480 Fluxmeter rather than having to purchase new items from Lake Shore Interfacing is made easy with the simple software functions available For those lacking time or technical expertise to make their own coils Lake Shore offers a line of factory calibrated coils and probes Special designs to meet specific applications are also available Power configurations the instrument is configured at the factory for customer selected power as follows 1 100V US NEMA 5 15 2
6. 7 2 1 100 cm Field Probe For years the most common field probe had 100 cm area turns Specifications are defined as follows See Figure 7 1 Coil Resistance approx Average Coil Diameter Operating Temp Range 10 to 40 C Input Resistance 100 KQ 30 mVs 3 tesla 300 mVs 30 DC Ranges 3 mVs 300 mT tesla 30 mVs 3 tesla 6 FT CABLE TO FLUXMETER 0 75 DIA MAX pl 4 APPROX SENSING COIL NOTE 4 IS DESIGNATED AS THAT FLUX PASSING THROUGH THE COIL INTO THE SIDE WITH THE LAKE SHORE LOGO ON THE PROBE HANDLE F 480 7 1 eps Figure 7 1 100 cm Field Probe Accessories Coils and Probes 7 3 Lake Shore Model 480 Fluxmeter User s Manual 7 2 2 30 cm Field Probe For measurements in narrow gaps or where field gradients dictate the use of a smaller coil diameter Lake Shore offers the 30cm field probe Specifications are defined in as follows See Figure 7 2 Area Turns approx 30 cm Coil Resistance approx 1100 Average Coil Diameter 0 39 cm Frequency Range 10 kHz Operating Temp Range 10 to 40 C Input Resistance suggested 100 KQ 300mVs 100 T DC Ranges 30mVs 10 T 6 FT CABLE TO FLUXMETER N SENSING COIL NOTE 4 IS DESIGNATED AS THAT FLUX PASSING THROUGH THE COIL INTO THE SIDE WITH THE LAKE SHORE LOGO ON THE PROBE HANDLE F 480 7 2 eps Figure 7 2 30 cm Field Probe 7 4 Accessories Coils and Probes Lake Shore Model 480 Fluxmeter
7. GND gt 7 GND 2 RD in FC 2 TD out 3 TD out HS 3 RD iN 1 NC SEN KE 4 RTS out 7 DTR tied to 4 P gt 5 CTS in 8 NC 8 DCD in 6 DSR in TT _20 DTR out 4 DTR out 6 DSR in Model 480 to PC Interface using Null Modem Adapter Model 480 DE 9P Null Modem Adapter PC DE 9P 5 GND gt 5 GND 2 RD in FF 3 TD out 3 TD out oo 2 RD iN 1 NC AA 4 DTR out 6 DSR in SE D s 1 DCD in 4 DTR out 6 DSR in 7 DTR tied to 4 8 CTS in 8 NC A SA 9 NC 9 NC NOTE Same as null modem cable design except PC CTS is provided from the Model 480 on DTR Service and Calibration Lake Shore Model 480 Fluxmeter User s Manual 8 5 2 IEEE 488 Interface Connector Connect to the IEEE 488 Interface connector on the Model 480 rear with cables specified in the IEEE 488 1978 standard document The cable has 24 conductors with an outer shield The connectors are 24 way Amphenol 57 Series or equivalent with piggyback receptacles to allow daisy chaining in multiple device systems The connectors are secured in the receptacles by two captive locking screws with metric threads The total length of cable allowed in a system is 2 meters for each device on the bus or 20 meters maximum A system may be composed of up to 15 devices Figure 8 6 shows the IEEE 488 Interface connector pin location and signal nam
8. PRINT TIMEOUT 2000 Read timeout may need more BAUDS 9600 TERMS CHR 13 CHR 10 Terminators are lt CR gt lt LF gt OPEN COM1 BAUDS 0 7 1 RS FOR RANDOM AS 1 LEN 256 LINE INPUT ENTER COMMAND or EXIT CMDS Get command from keyboard CMD UCASES CMDS Change input to upper case IF CMDS EXIT THEN CLOSE 1 END Get out on Exit CMDS CMDS TERMS PRINT 1 CMDS Send command to instrument IF INSTR CMDS lt gt 0 THEN Test for query RS If query read response N 0 Clr return string and count WHILE N lt TIMEOUT AND INSTR RS TERMS 0 Wait for response INS INPUT LOC 1 1 Get one character at a time IF INS THEN N N 1 ELSE N 0 Add 1 to timeout if no chr RSS RSS INS Add next chr to string WEND Get chrs until terminators IF RSS lt gt THEN See if return string is empty RS MIDS RS 1 INSTR RS TERMS 1 Strip off terminators PRINT RESPONSE RS Print response to query ELSE PRINT NO RESPONSE No response to query END IF END IF Get next command GOTO LOOP1 6 18 Computer Interface Operation Lake Shore Model 480 Fluxmeter User s Manual 6 2 3 3 Program Operation Once either example program is running try the following commands and observe the response of the instrument Input from the user is shown in bold and terminators are added by the program The word term indicates the required terminators includ
9. CLS Nothing Clears the bits in the Status Byte Register and Standard Event Status Register and terminates all pending operations Clears the interface but not the instrument The instrument related command is RST Configure Status Reports in the Standard Event Status Register ESE lt bit weighting gt Nothing Each bit is assigned a bit weighting and represents the enable disable status of the corresponding event flag bit in the Standard Event Status Register To enable an event flag bit send the command ESE with the sum of the bit weighting for each desired bit Refer to the ESR command for a list of event flags To enable event flags 0 3 4 and 7 send the command ESE 143 term 143 is the sum of the bit weighting for each bit Bit Bit Weighting Event Name 0 1 OPC 3 8 DDE 4 16 EXE 7 128 PON 143 Query the Configuration of Status Reports in the Standard Event Status Register ESE lt ESE bit weighting gt Format nnn term The integer returned represents the sum of the bit weighting of the enable bits in the Standard Event Status Enable Register Refer to the ESR command for a list of event flags Query Standard Event Status Register ESR lt ESR bit weighting gt Format nnn term Queries for various Model 480 error conditions and status The integer returned represents the sum of the bit weighting of the event flag bits in the Standard Event Status Register Bit Bit Weighting Event Name Bit Bit
10. User s Manual Model 480 Fluxmeter w Lake Shore CRYOTRONICS Lake Shore Cryotronics Inc 575 McCorkle Blvd Westerville Ohio 43082 8888 USA E mail sales lakeshore com service lakeshore com Visit our website at www lakeshore com Fax 614 891 1392 Telephone 614 891 2243 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 disclosed 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 modifications or products at any time without notice Lake Shore shall not be liable for errors contained herein or for incidental or consequential damages in connection with furnishing performance or use of this material Revision 2 1 P N 119 028 10 March 2015 Lake Shore Model 480 Fluxmeter User s Manual 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 Purchaser s physical receipt of the Product the Warranty Period If Lake Shore receives notice o
11. di where V volts A meters B tesla N number of coil turns and t seconds Calculation of Minimum Rise Time What is the fastest pulse allowable When the area turns NA of the coil and the desired peak field Bp are known the above equations can be used to calculate the minimum rise time tp NAB V SI units Calculations of minimum rise times are given for two standard Lake Shore probes V 60 volts and cm x 10 meters NA 30 cm If Bp 3 tesla tp gt 150 us If Bp 5 tesla tp gt 250 us If Bp 7 tesla tp gt 350 us NA 100 cm If Bp 3 tesla tp gt 500 us If Bp 5 tesla tp gt 833 us If Bp 7 tesla tp gt 1200 us 1 2 ms Calculation Of Area Turns Often the user will make his own coil to be used with a specific magnetizing fixture The maximum area turns NA needs to be calculated to ensure the 60 volt input limit is not exceeded The equation below can be used NA lt Vtp Bp meters SI units For example if the rise time tp is 5 us and the peak field Bp is 3 tesla then the following is a calculation of the maximum area turns NA to ensure the coil voltage will not exceed 60 volts NA lt 60V 5 x 10 s 3 T 1 x 104 meter 1 cm Magnetic Measurement Overview 2 5 2 2 2 2 1 Lake Shore Model 480 Fluxmeter User s Manual Making AC Measurements Traditionally integrating fluxmeters make DC flux measurements where the measured field changes i
12. Bus Control Commands Continued Finally Addressed Bus Control Commands are Multiline commands that must include the Model 480 listen address before the instrument responds Only the addressed device responds to these commands The Model 480 recognizes three of the Addressed Bus Control Commands SDC Selective Device Clear The SDC command performs essentially the same function as the DCL command except that only the addressed device responds GTL Go To Local The GTL command is used to remove instruments from the remote mode With some instruments GTL also unlocks front panel controls if they were previously locked out with the LLO command SPE Serial Poll Enable and SPD Serial Poll Disable Serial polling accesses the Service Request SRQ Status Register This status register contains important operational information from the unit requesting service The SPD command ends the polling sequence 6 1 2 2 Common Commands Common Commands are addressed commands which create commonalty between instruments on the bus All instruments that comply with the IEEE 488 1987 standard share these commands and their format Common commands all begin with an asterisk They generally relate to bus and instrument status and identification Common query commands end with a question mark Refer to Paragraph 6 3 for a list of all Model 480 common commands 6 1 2 3 Interface and Device Specific Commands Device Specific Commands
13. 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 480 should consider the following Leave no unused or unterminated cables attached to the instrument e Make cable runs as short and direct as possible e Do not tightly bundle cables that carry different types of signals Lake Shore Model 480 Fluxmeter User s Manual This Page Intentionally Left Blank Lake Shore Model 480 Fluxmeter User s Manual Table of Contents Chapter Paragraph Title Page 1 INTRODUCTION H 1 1 1 0 GENERA eege Eege ee tes ene etd ta N ee o td ade 1 1 1 1 PRODUCT DESCRIPTION coocococcccccccconcnononcnonnnnnoncnnnnnn nono ad aada a aeaa e iaa poiana 1 1 1 2 SPEGCIFICATIONS cia eke ate a ia r aa a aet 1 2 1 3 SAFETY SUMMA EE 1 4 1 4 SAFETY SYMBOLS E es A ae te ie eee EE 1 4 2 MAGNETIC MEASUREMENT OVERVIEW 2 1 2 0 GENERAL wiss2 cit teins ete ee id Se 2 1 2 1 INTEGRATING INSTRUMENTS eee eeeeaeeeeaeeceeeeecaaeeesaaeeeeeeeseaeeesaeeeeeeeeaes 2 1 2 1 1 What Is An Integrator cccceccceceeceeeeeeeeeeaeeseneeceaeeecaaeeeeaaeseeeeecaeeesaaeeseaeeseaeeessaeeeeaaeeeneees 2 1 2 1 2 Why Integrators Are Used For Magnetic Measurement oocccccinnnocccnnoccccnnnnnoncnnnnnancnnnnnano 2 1 2 1 3 Important Integrator Characteristics oooonoconnidincinnnnnnnnnccnnncccnnrccnnarnnnnrc cnc crac anna 2 2 2 1 4 Reducing Integrator Dm AANEREN 2 3 2 1 5 Dielectric Der pe
14. Locate EPROM U53 M480 HEX on the main circuit board Note orientation of existing IC M480 HEX 113 590 Match notch Le 02 26 99 EPROM to notch in socket eprom eps Use IC puller to remove existing EPROM from socket Noting orientation of new EPROM use an IC insertion tool to place new device into socket Install four Phillips head screws attaching transformer bracket to the Model 480 chassis Follow the top of enclosure INSTALLATION procedure in Paragraph 8 6 2 NO Ole 8 8 Service and Calibration Lake Shore Model 480 Fluxmeter User s Manual Operating Software EPROM Front Rear r 1 IS I gt i Power Inlet C 480 8 7 eps Figure 8 7 Location of Operation Software EPROM 8 8 ERROR MESSAGES The following is a list of Model 480 error messages that may be seen during normal operation NOVRAM Defective Cannot write to the NOVRAM NOVRAM is physically malfunctioning Return instrument to Lake Shore for repair and recalibration NOVRAM Corrupt Information in the NOVRAM is not recognized Cycle the power to see if the error message disappears If that does not resolve the problem press the Escape and Enter keys to initialize the NOVRAM This will permit continued operation but the calibration data will be deleted Return instrument to Lake Shore for repair and recalibration Invalid Calibration Press the Escape and Enter keys simultaneously The instrument is out o
15. Remarks Returns EO parameter 0 EOI enabled 1 EOI disabled 6 30 Computer Interface Operation FILT Input Returned Remarks FILT Input Returned Remarks FNUM Input Returned Remarks FNUM Input Returned Remarks FWIN Input Returned Remarks FWIN Input Returned Remarks KEY Input Returned Remarks LOCK Input Returned Remarks Lake Shore Model 480 Fluxmeter User s Manual Configure Display Filter Function Off On FILT lt off on gt Nothing Configures the display filter function 0 Off 1 On Quiets the display reading by a degree depending on the points FNUM and window FWIN settings Query Display Filter Function Off On FILT 0 or 1 Format n term Queries the display filter function 0 Off 1 On Quiets the display reading by a degree depending on the points FNUM and window FWIN settings Configure Display Filter Points FNUM lt points gt Nothing Configures the display filter points lt points gt integers 2 thru 64 In general the higher the number the longer the display settle time Query Display Filter Points FNUM lt points gt Format nn term Queries the display filter points lt points gt integers 2 thru 64 In general the higher the number the longer the display settle time Configure Display Filter Window FWIN lt window gt Nothing Configures the display filter window lt window g
16. These conditions will likely be corrected during instrument setup An incomplete sequence error message Paragraph 8 8 or blank display may indicate a problem Check all connections and line input power refer to Chapter 8 If problems persist call Lake Shore DISPLAY DEFINITION The Model 480 has a 2 line by 20 character vacuum fluorescent display During normal operation the instrument displays both readings and annunciators The top line of the display shows the DC DC Peak AC or AC Peak reading value followed by the prefix and selected units In dual peak mode the top line shows the positive peak and the bottom line the negative peak Annunciators follow to the right of the reading When changing settings with the keypad display messages prompt the user with brief instructions Peak Field Reading Prefix Units Vs MxN AC Alarm Remote Hold Orientation u m _ WEN Ven Who Mad or On Mode Pos k orM T G Wbcm orA DC Neg F 480 4 1 eps Figure 4 1 Model 480 Normal Display Definition Basic Operation 4 1 Lake Shore Model 480 Fluxmeter User s Manual 4 3 READING FORMAT The fundamental measurement units of the Model 480 are volt seconds V s therefore many Model 480 specifications appear in that unit With the input of appropriate coil parameters the user may set the instrument to display in any of 11 magnetic units Reading range and display resolution are based on coil parameters and units chosen W
17. V s international system of units SI A universal coherent system of units in which the following seven units are considered basic meter kilogram second ampere kelvin mole and candela The International System of Units or Systeme International d Unit s SI was promulgated in 1960 by the Eleventh General Conference on Weights and Measures For definition spelling and protocols see Reference 3 for a short convenient guide interpolation table A table listing the output and sensitivity of a sensor at regular or defined points which may be different from the points at which calibration data was taken intrinsic coercivity The magnetic field strength H required to reduce the magnetization M or intrinsic induction in a magnetic material to zero intrinsic induction The contribution of the magnetic material Bi to the total magnetic induction B Bi B HoH SI Bi B H cgs isolated neutral system A system that has no intentional connection to ground except through indicating measuring or protective devices of very high impedance Kelvin K The unit of temperature on the Kelvin Scale It is one of the base units of SI The word degree and its symbol are omitted from this unit See Temperature Scale for conversions Kelvin Scale The Kelvin Thermodynamic Temperature Scale is the basis for all international scales including the ITS 90 It is fixed at two points the absolute zero of temperature 0 K and the tri
18. are entered first m Required only if a significant percentage of input resistance Otherwise set to 0 Q e Required coil parameter for the units selected Advanced Operation 5 1 Lake Shore Model 480 Fluxmeter User s Manual Units Selection Continued 5 2 5 3 To select a unit press the Units key The following screen appears Sel ect Wi th aF Flux Turnss Us Use the A or Y keys to cycle through the different units V s MXN WbN V so Wbd Mx T G Wb cm or A When the desired unit displays press the Enter key to accept it or the Escape key to exit the screen and revert to the previous unit COIL PARAMETERS Most measurements made with a fluxmeter require some information about the sense coil The Model 480 offers several ways to obtain and enter the coil parameters This section briefly outlines the coil related features available in the Model 480 Lake Shore coils and probes already have necessary coil parameters loaded into them To use a Lake Shore probe power the instrument off attach the probe and power it back on During the power up sequence the instrument will read all loaded coil parameters and coil setup is complete Most parameters are fixed and can not be changed by the user The percent constant can be changed and stored in the probe refer to Paragraph 5 6 to allow percent operation Users can purchase the Model FCBL 6 accessory from Lake Shore and program their own coil param
19. ee tao nani amar Molar Volume Ideal Gas To 273 15K po 1 atm Data abbreviated to 4 decimal places from CODATA Bulletin No 11 ICSU CODATA Central Office 19 Westendstrasse 6 Frankfurt Main Germany Copies of this bulletin are available from this office Reference Information
20. exit to end program Command Response 15 Type in a command or query in the Command box as described in Paragraph 6 1 4 5 16 Press Enter or select the Send button with the mouse to send command 17 Type Exit and press Enter to quit 6 8 Computer Interface Operation Lake Shore Model 480 Fluxmeter User s Manual Table 6 2 Visual Basic IEEE 488 Interface Program Public gSend As Boolean Global used for Send button state Private Sub cmdSend Click gSend True End Sub Routine to handle Send button press Set Flag to True Private Sub Form Load Dim strReturn As String Dim term As String Dim strCommand As String Dim intDevice As Integer frmIEEE Show term Chr 13 amp Chr 10 strReturn Call ibdev 0 12 0 T10s 1 amp H140A intDevice Call ibconfig intDevice ibcREADDR 1 Do Do DoEvents Loop Until gSend True gSend False strCommand frmIEEE txtCommand Text strReturn strCommand UCase strCommand If strCommand EXIT Then End End If Call ibwrt intDevice strCommand amp term If ibsta And EERR Then do error handling if needed End If If InStr strCommand lt gt 0 Then strReturn Space 100 Call ibrd intDevice strReturn If ibsta And EERR Then do error handling if needed End If If strReturn lt gt Then strReturn RTrim strReturn Main code section Used to return response Terminators Data string sent to
21. no prefix k or M are allowed for most coil parameters and field settings Not all prefixes make sense for every parameter but they are left active to ensure the most flexibility for the user If it is unclear which prefix to use set the prefix to _ for no prefix and the instrument unit shown on the setting screen will be used Basic Operation 4 3 Lake Shore Model 480 Fluxmeter User s Manual 4 6 QUICK START PROCEDURES The quick start procedures steps the user through DC measurements with a typical probe or coil and permanent magnet These procedures enable a user new to the Model 480 to verify the operation of the instrument Integrator measurement is detailed in Paragraph 4 6 1 flux measurement in Paragraph 4 6 2 flux density measurement in Paragraph 4 6 3 moment measurement in Paragraph 4 6 4 and potential measurement in Paragraph 4 6 5 4 6 1 DC Integrator Measurement In Units of Ve WbN or MxN Use the following procedure to take an integrator measurement 1 Ensure power is turned Off O CAUTION Always turn off power to the Fluxmeter before making any rear panel PROBE INPUT or COIL INPUT connections 2 Attach the probe or coil to rear of the Fluxmeter Refer to Paragraph 3 4 for COIL INPUT and Paragraph 3 5 for PROBE INPUT connection instructions Turn power On I Press the Units key For this procedure we will use Maxwell turns MxN Press the a or v keys until Flux Turns MxN is displayed on the scre
22. of shipment Refer to the standard Lake Shore Warranty on the A Page behind the title page Repackaging For Shipment To return the Model 480 probe coil or accessories for repair replacement or recalibration obtain a Return Goods Authorization RGA number from Technical Service in the United States or from the authorized sales service representative from which the product was purchased Instruments may not be accepted without a RGA number When returning an instrument for service Lake Shore must have the following information before attempting any repair 1 Instrument model and serial number User name company address and phone number Malfunction symptoms Description of system Returned Goods Authorization RGA number oP ON Wrap instrument in a protective bag and use original spacers to protect controls Repack the system in the Lake Shore shipping carton if available and seal it with strong paper or nylon tape Affix shipping labels and FRAGILE warnings Write the RGA number on the outside of the shipping container or on the packing slip Instrument Setup 3 1 Lake Shore Model 480 Fluxmeter User s Manual 3 2 REAR PANEL DEFINITION CAUTION Verify AC Line Voltage shown in the fuse holder window is appropriate for the intended AC power input Also remove and verify the proper fuse is installed before plugging in and turning on the instrument CAUTION Always turn off the instrument before making any rear pa
23. strReturn No Response End If frmSerial txtResponse Text strReturn strHold ZeroCount 0 End If Loop End Sub Timeout at 2 seconds Reset timeout for each character Read in one character Add next character to string Get characters until terminators Check if string empty Term 1 Strip terminators Send No Response Put response in textbox on main form Reset holding string Reset timeout counter Private Sub Timerl_Timer frmSerial Timerl Enabled False End Sub Routine to handle Timer interrupt Turn off timer Computer Interface Operation 6 17 Lake Shore Model 480 Fluxmeter User s Manual 6 2 3 2 Quick Basic Serial Interface Program Setup The serial interface program listed in Table 6 7 works with QuickBasic 4 0 4 5 or Qbasic on an IBM PC or compatible running DOS or in a DOS window with a serial interface It uses the COM1 communication port at 9600 Baud Use the following procedure to develop the Serial Interface Program in Quick Basic Start the Basic program Enter the program exactly as presented in Table 6 7 Adjust the Com port and Baud rate in the program as necessary Lengthen the TIMEOUT count if necessary Save the program Run the program Type a command query as described in Paragraph 6 2 3 3 oN oar wn Type EXIT to quit the program Table 6 7 Quick Basic Serial Interface Program CLS Clear screen PRINT SERIAL COMMUNICATION PROGRAM
24. the Enter key You will see the following message ADJUSTING DRIFT For 25 Seconds 13 Make the test measurement 14 If the reading appears to be drifting refer to the Drift Adjust discussion in Paragraph 5 9 4 4 Basic Operation 4 6 2 Lake Shore Model 480 Fluxmeter User s Manual DC Flux Measurement In Units of V so Mx or Wb Use the following procedure to take a flux measurement 1 Ensure power is turned Off O CAUTION Always turn off power to the Fluxmeter before making any rear panel PROBE INPUT or 10 11 12 13 14 15 COIL INPUT connections Attach the probe or coil to rear of the Fluxmeter Refer to Paragraph 3 4 for COIL INPUT and Paragraph 3 5 for PROBE INPUT connection instructions Turn power On I Press the Units key For this procedure we will use Webers Wb Press the a or v keys until Flux 0 Wbo is displayed on the screen then press the Enter key A quick message that details which input parameters are necessary to perform calculations in the units you have selected will appear then disappear Press the Coil Setup key For this procedure we will assume an Input Resistance of 100 KQ Press the a or v keys until Input R 100k is displayed on the screen press the Enter key then the Escape key If the coil resistance is less than 100 Q or is unknown the default value of 0 Q is acceptable and you may skip this step Otherwise press the Coil Setup key Press the
25. 1 Sense coils also have a frequency response which can limit accuracy AC measurements can be susceptible to noise because most fields are small and require a low measurement range It may be necessary to shield environmental noise during low field AC measurements The RMS converter in the Model 480 requires a significant signal amplitude for proper operation AC measurements are specified with a minimum reading for each range because of the RMS converter If the input amplitude is below the specified minimum the AC annunciator will blink on the instrument display The minimum reading is different for AC peak operation because the RMS converter is bypassed To select AC mode press the AC DC key AC operation is indicated by the letters AC on the normal display to the right of the units indicator 4 Metering Response me dan Ab Respohe Giap 98 26 94 92 100 1K 10K 100K 200K S 90 P 480 5 1 bmp Figure 5 1 Model 480 AC Frequency Response Advanced Operation 5 13 Lake Shore Model 480 Fluxmeter User s Manual 5 11 PEAK HOLD AND PEAK RESET The Model 480 has high speed peak hold hardware that can be used to capture positive and negative peak values Software stores the measured peaks to prevent any sag in the hold circuits from changing the display value Peak hold operation can be used during DC or AC operation 5 11 1 5 11 2 5 11 3 Peak Hold in DC Mode The peak hold feature has ver
26. 20 0 0338 0 8118 30 0 0100 0 2546 40 0 00314 0 07987 ampere The constant current that if maintained in two straight parallel conductors of infinite length of negligible circular cross section and placed one meter apart in a vacuum would produce between these conductors a force equal to 2 x 107 newton per meter of length This is one of the base units of the SI ampere turn A MKS unit of magnetomotive force equal to the magnetomotive force around a path linking one turn of a conducting loop carrying a current of one ampere or 1 26 gilberts ampere meter A m The SI unit for magnetic field strength H 1 ampere meter 47 1000 oersted 0 01257 oersted analog data Data represented in a continuous form as contrasted with digital data having discrete values analog output A voltage output from an instrument that is proportional to its input From an instrument such as a digital voltmeter the output voltage is generated by a digital to analog converter with a discrete number of voltage levels anode The terminal that is positive with respect to the other terminal when the diode is biased in the forward direction Anode Pel cathode area A measure of the size of a two dimensional surface or of a region on such a surface area turns A coil parameter produced by the multiplication of a magnet s area and number of turns Gives an indication of the sensitivity of a coil In the Model 480 the area turns of a coil must be entered
27. 41107 H m N turns A area in m2 length in m and Leon is in henries H Equations for flat search and Helmholtz coils are more complicated because there is no simple relationship between inductance and length but the effects of area and number of turns remain consistent There is capacitance between each turn of wire in a coil Ccoi Impedance resulting from the capacitance itself is most often negligible at frequencies below 50 kHz However the capacitance reacts with the coil inductance to make the coil resonate Operating anywhere near the coil resonant frequency gives unpredictable results The frequency of resonance is 1 ail Lg Lake Shore Coils and Probes It may be desirable to purchase pre fabricated sense coils optimized for Model 480 use Lake Shore offers search and Helmholtz coils Dimensions and specifications appear in Chapter 7 They are designed for every day use with well secured windings and strain relief at connection points Factory calibration ensures accurate measurements from the start without field calibrating the coil in a magnet standard They also ensure interchangeability of probes and fluxmeters for reproducible measurements Lake Shore calibrations use the most accurate standards available Each coil comes with calibration data that may include number of turns area and resistance Lake Shore sense coils are very easy to use Calibrated coil parameters are usually pre programmed into non vola
28. 480 must return information Over IEEE 488 the last query response is sent when addressed to talk For example UNITS 8 UNITS sets the units to gauss and immediately queries unit status 6 2 1 Serial Interface Hardware Configuration Below is a technical description of the Serial Interface Table 6 2 lists communication parameters Terminators are fixed to Carriage Return CR and Line Feed LF The serial interface connector is a 9 Pin D connector Table 6 4 Serial Interface Specifications Transmission Three Wire Connector 9 Pin D Connector Timing Format Asynchronous RS 232C Electrical Format Transmission Mode Half Duplex Baud Rate 300 1200 or 9600 Bits per Character 1 Start 7 Data 1 Parity and 1 Stop Parity Type Odd Data Interface Levels Transmits and Receives Using EIA Voltage Levels Fixed Terminator CR ODH LF OAH 6 2 2 Serial Interface Settings To use the Serial Interface set the Baud rate Press Baud to display the following screen Sel ect i th aF Baud 3 1 2 43 96 Press the s or t keys to cycle through the choices of 300 1200 or 9600 Baud Press Enter to accept the new number or Escape to keep the existing setting and return to the normal display 6 14 Computer Interface Operation Lake Shore Model 480 Fluxmeter User s Manual 6 2 3 Serial Interface Example Programs Two BASIC programs are included to illustrate the serial communication functions of the instrument The first program was written in Visual Basic R
29. 6 2 SERIAL I O INTERFACE RS 232C is a standard of the Electronics Industries Association EIA and one of the most common interfaces between a computer and electronic equipment The Customer supplied computer must have a Serial Interface port The Model 480 Serial Interface complies with the electrical format of the RS 232C Interface Standard A Serial Interface between the computer and the Model 480 permits remote monitoring and control of Model 480 control functions which in turn controls Model 480 operation See Figure 6 2 The Serial Interface can both transmit and receive information In transmit Tx mode the instrument converts parallel information to serial and sends it over a cable up to 50 feet long or longer with proper shielding In receive Rx mode the instrument converts serial information back to parallel for processing Refer to Paragraph 6 2 1 for serial interface hardware configuration and adapters Paragraph 6 2 2 for serial interface settings and Paragraph 6 6 3 for a sample BASIC programs to establish communications between the computer and the Model 480 The Serial Interface shares Device Specific commands with the IEEE 488 interface listed in Paragraph 6 3 However without the advantage of the IEEE 488 Architecture there are several limitations e No Bus Control Commands apply e Only IDN and RST Common Commands are usable e Terminators are fixed to CRLF A query must be added to the end of a command string if the Model
30. Commands and queries should have a space separating the command and associated parameters Leading zeros and zeros following a decimal point are not needed in a command string but are sent in response to a query A leading is not required but a leading is required 6 1 5 Troubleshooting New Installation Check instrument address Always send terminators Send entire message string at one time including terminators Send only one simple command at a time until communication is established Be sure to spell commands correctly and use proper syntax Attempt both Talk and Listen functions If one works but not the other the hardware connection is working so look at syntax terminators and command format If only one message is received after resetting the interface check the repeat addressing setting It should be enabled 02 Nk N Old Installation No Longer Working 8 Power instrument off then on again to see if it is a soft failure 9 Power computer off then on again to see if the IEEE card is locked up 10 Verify that the address has not been changed on the instrument during a memory reset 11 Check all cable connections Intermittent Lockups 12 Check cable connections and length 13 Increase delay between all commands to 50 ms to make sure instrument is not being over loaded Computer Interface Operation 6 13 Lake Shore Model 480 Fluxmeter User s Manual
31. Constant Command COILKH COILKP COILKP COILN COILN COILNUM COILNUM COILR COILR COILSAVE DACCRS DACCRS DACFINE DACFINE DCRES DCRES DFLT 99 DRAUTO DRTHR DRTHR DRTRAK DRTRAK FILT FILT FNUM FNUM FWIN FWIN KEY LOCK LOCK OPTIN PCTMUL PCTMUL PCTSET PEAK PEAK PEAKM PEAKM PKNEG PKPOS PKRST PROBE PROBE RDRST READ RELAYH RELAYH RELAYL RELAYL RELAYM RELAYM RNGAC RNGAC RNGDC RNGDC RNGMX UNITS UNITS Function Query Helmholtz Coil Constant Set Potential Coil Constant Query Potential Coil Constant Set Coil Number of Turns Query Coil Number of Turns Configure Coil Number Parameter Query Coil Number Parameter Set Coil Resistance Query Coil Resistance Initiate Coil Save Command Set Coarse Drift DAC Value Query Coarse Drift DAC Value Set Fine Drift DAC Value Query Fine Drift DAC Value Set DC Resolution Query DC Resolution Set To Factory Defaults Initiate Auto Drift Correction Set DriftTrak Threshold Level Query DriftTrak Threshold Level Configure DriftTrak Function Off On Query DriftTrak Function Off On Configure Filter Function Off On Query Filter Function Off On Configure Display Filter Points Query Display Filter Points Configure Display Filter Window Query Display Filter Window Query Keypad Status Configure Keypad Lock Function Query Keypad Lock Function Query Optional Input Set Percent Multiplier Constant Query Percent Multiplier Constant Initiat
32. Dut Use the a or v keys to cycle between triggering the inside In or outside Out the high and low setpoints Once selected press the Enter key After the Alarm In Out display the next display is the Audible On Off screen Sel ect Wi th aF Audi bl e On 0FF Use the a or v keys to cycle between turning the audible alarm On or Off Once selected press the Enter key then press the Escape key Advanced Operation 5 17 Lake Shore Model 480 Fluxmeter User s Manual Alarm Alarm Alarm H Alarm Alarm Off On Off On Off 3 kG 2 kG 1 kG 0 kG 1 kG 2 kG 3 kG Example of operation with alarm triggered Low Alarm by readings INSIDE Point user defined setpoints High Alarm Point C A_inside eps Alarm Alarm Alarm Alarm Alarm On Off On Off On 3 kG 2 kG 1 kG 0 kG 1 kG 2 kG 3 kG Example of operation with alarm triggered by Low Alarm readings OUTSIDE user Point defined setpoints High Alarm Point C A_outside eps Figure 5 2 Examples of Alarm Activation Inside and Outside High and Low Setpoints 5 14 2 Relay Setup There are three relays on the Model 480 Each relay can be set to one of three modes Automatic On or Off In automatic mode the relays follow the alarm status The high relay is activated when the measured value exceeds the high setpoint the low alarm relay is activated when the measured value is below the low setpoint and the middle relay is active whe
33. Enter key until Enter Coil R is displayed Use the numeric keypad to enter the coil resistance then press the Enter key The cursor will jump to a space before the Q symbol Use the a or v keys to select prefix _ for Q or k for kQ Press the Enter key then the Escape key Press the Coil Setup key Press the Enter key until Enter Turns is displayed Use the numeric keypad to enter the number of turns then press the Enter key The cursor will jump to a space before Turns Use the a or v keys to select prefix u m _ k or M Press the Enter key then the Escape key NOTE All other settings Area Turns Helmholtz Constant etc are ignored when using flux units Press the AC DC key until DC is displayed on the screen Press the Peak Hold key until Peak Hold Off is displayed on the screen Press the Range key Use the a or v keys to select the range appropriate to your measurement Press the Reading Reset key If the instrument has just been turned on allow it to warm up for at least 10 minutes before proceeding Otherwise proceed to Step 13 Press the Drift Adjust key Use the a or v keys until Begin Auto Adjust is displayed Press the Enter key You will see the following message ADJUSTING DRIFT For 25 Seconds Make the test measurement If the reading appears to be drifting refer to the Drift Adjust discussion in Paragraph 5 9 Basic Operation 4 5 Lake Shore Model 480 Fluxme
34. Output set to DC Set Model 480 Analog output to manual 100 Corrected Offset Constant Voltmeter reading 1 10 000 Vdc 20 Set Model 480 Analog output to manual 100 Corrected DAC Gain Constant 20 Voltmeter reading 2 Voltmeter reading 1 Send Corrected DAC Offset Constant using the form CALCOFF xxxxxx NOTE This value must be between 0 005 and 0 A value outside this range indicates a major malfunction of the Model 480 that requires repair 7 Send Corrected DAC Gain Constant using the form CALCGAIN lt xxxxxx gt NOTE This value must be between 0 95 and 1 0 A value outside this range indicates a major malfunction of the Model 480 that requires repair E NOS 8 9 8 Finalize Calibration 1 Finalize calibration by sending POKEM F207 31 over the computer interface 2 Set the unit serial number using the form SNUM xxxxxx sent over the interface 3 The calibration is now complete 8 14 Service and Calibration Lake Shore Model 480 Fluxmeter User s Manual APPENDIX A GLOSSARY OF TERMINOLOGY accuracy The degree of correctness with which a measured value agrees with the true value electronic accuracy The accuracy of an instrument independent of the sensor sensor accuracy The accuracy of a temperature sensor and its associated calibration or its ability to match a standard curve algorithm A set of well defined rules for the solution of a problem in a finite number
35. Returned Remarks ALML Input Returned Remarks ALMS Input Returned Remarks ANOCON Input Returned Remarks ANOCON Input Returned Remarks ANOH Input Returned Remarks ANOH Input Returned Remarks ANOL Input Returned Remarks Lake Shore Model 480 Fluxmeter User s Manual Set Alarm Low Point Value ALML nnn nnnEznn Nothing Sets the low point of the alarm function Enter up to 6 digits with decimal point in exponential form Place decimal appropriate to range Query Alarm Low Point Value ALML t nnn nnnE nn Returns the low point of the alarm function up to 6 digits with decimal point in exponential form Query Alarm Status ALMS lt alarming gt lt high status gt lt low status gt Format n n n term Queries alarm status 0 Off no alarm exists 1 On alarm exists Set Analog Out Control Value ANOCON nnn nnnE tnn Nothing Sets the percentage of full scale of the analog output in manual mode Enter up to 6 digits and a decimal point in exponential form Valid values are from 100 to 100 Query Analog Out Control Value ANOCON nnn nnnE nn Returns the percentage of full scale of the analog output in manual mode up to 6 digits anda decimal point in exponential form Set Analog Out High Point Value ANOH nnn nnnE nn Nothing Sets the high point of the analog out function in user mode Enter up to 6 digits with decimal poi
36. Run IBTEST to test software configuration Do not install the instrument before running IBTEST Run IBCONF to configure the GPIB PCII IIA board and dev 12 Set the EOS byte to OAH and Enable Repeat Addressing to Yes See Figure 6 3 IBCONF modifies gpib com o om E wo LD 7 Connect the instrument to the interface board and power up the instrument Verify the address is 12 and terminators are CR LF 6 1 4 4 Quick Basic Program The IEEE 488 interface program in Table 6 6 works with QuickBasic 4 0 4 5 or Qbasic on an IBM PC or compatible running DOS or in a DOS window It assumes your IEEE 488 GPIB card is installed and operating correctly refer to Paragraph 6 1 4 3 Use the following procedure to develop the Serial Interface Program in Quick Basic 1 Copy c gpib pc Qbasic qbib obj to the QuickBasic directory QB4 2 Change to the QuickBasic directory and type link q qbib obj bqlb4x lib where x O for QB4 0 and 5 for QB4 5 This one time only command produces the library file qbib qlb The procedure is found in the National Instruments QuickBasic readme file Readme qb 3 Start QuickBasic Type qb l qbib qlb Start QuickBasic in this way each time the IEEE interface is used to link in the library file 4 Create the IEEE example interface program in QuickBasic Enter the program exactly as presented in Table 6 3 Name the file ieeeexam bas and save 5 Run the program 6 Type acommand query as described in Parag
37. Set Coil Area TUrns ococoocccnococoncccnnnnnnnannnancccnno 1 00000 1 00000 cm2N COILIN Set Coil Input Terminal See 100 kQ COILKH Set Coil Helmholtz Constant 1 00000 1 00000 cm COILKP Set Coil Potential Constant 1 00000 1 00000 A COILN Set Coil Number of Turns oooooccocccccocininaccnancccnns 1 00000 1 00000 COILNUM Set Coil Number erate meas 1 COILR Set Coil Resistance cccceesceeeeeeeseeeeeneees 0 00000 0 00000 Q FILT Set Display Filter Function oooooncccnnccinncccancccon eege Beer reg Off FNUM Set Filter Points 0 0 2 eceeseeeeeeeeeeeeeeeeeeeeeneeees Sii 8 FWIN Set Filter Window oooooocoococinnccconcccnocinonannancccnno Mita ati 1 LOCK Set Keyboard Lock Mode n ONS Off PCTMUL Set Percent Multiplier Constant 1 00000 1 00000 PEAK Set Peak Hold Function oooonocccnccnncccincccconccccn Distant Off PEAKM Set Peak Capture Mode CETE Dual Peak RELAYH Set High Relay Mode O PERET E ier Manual Off RELAYL Set Low Relay Mode coooooooocinccccocccccocicononcnancccnns Dido Manual Off RELAYM Set Middle Relay Mode n Dia Manual Off RNGAC Set AC Range eege gegen Ova eee 30 mV s RNGDC Set DC Hange nien iiai i ii Dira 300 mV s UNITS Set Display Unit Mad Vis Advanced Operation Lake Shore Model 480 Fluxmeter User s Manual This Page Intentionally Left Blank 5 24 Advanced Operation Lake Shore Model 480 Fluxmet
38. User s Manual 7 3 HELMHOLTZ COILS Lake Shore offers three Helmholtz coils 2 5 6 and 12 inch diameter Check the latest Lake Shore brochures or our website for any recent additions to this line These coils are accurately calibrated using field standards maintained at Lake Shore Most standards are traceable to physical standards such as a coil of carefully controlled dimensions or in some cases to proton resonance The coil constants are measured on the basis of the field generated by a current through the coil Users may connect to the Model 480 Fluxmeter with their own cable or a special Lake Shore cable A user supplied cable connects directly to the banana plugs on the Helmholtz and the back of the instrument and the user must manually input the necessary coil parameters listed on the label into the fluxmeter using the Coil Setup key Lake Shore supplies a special cable with all factory calibrated Helmholtz coils This cable attaches between the coil banana terminals and the D connector on the rear panel of the Model 480 Helmholtz coils are calibrated for use in Wb cm units Pertinent calibration information including the calibration constant and resistance are stored in Programmable Read Only Memory PROM located in the cable connector Users need only attach the coil to the Model 480 Fluxmeter turn on the instrument set the range and reset the zero before taking readings No manual input of coil parameters is necessary CAUTIO
39. adapter if not 3 Always send terminators 4 Send entire message string at one time including terminators Many terminal emulation programs do not 5 Send only one simple command at a time until communication is established 6 Be sure to spell commands correctly and use proper syntax Old Installation No Longer Working 7 Power instrument off then on again to see if it is a soft failure 8 Power computer off then on again to see if communication port is locked up 9 Verify that Baud rate has not been changed on the instrument during a memory reset 10 Check all cable connections Intermittent Lockups 11 Check cable connections and length 12 Increase delay between all commands to 100 ms to make sure instrument is not being over loaded Computer Interface Operation 6 19 Lake Shore Model 480 Fluxmeter User s Manual 6 3 IEEE 488 SERIAL INTERFACE COMMAND SUMMARY Command Function Common Commands CLS ESE ESE ESR IDN OPC OPC RST SRE SRE STB TST WAI Clear Interface Set Std Event Status Enable Query Std Event Status Enable Query Std Event Status Register Query Identification Set Operation Complete Query Operation Complete Reset Instrument Set Service Request Enable Query Service Request Enable Query Status Byte Query Self Test Wait To Continue Interface Commands ADDR ADDR BAUD BAUD END END MODE MODE TERM TERM Configure IEEE Address Query IE
40. adiress by Secondary GPIB Address NONE using the left and right arrow keys Tineout setting lec Serial Poll Timeout isec This address is used to campute the talk and listen addresses which Terminate Read on EOS Yes identify the board or device on the Set EOI with EOS on tkites Yes GPIB Valid primary addresses range Type of compare on EOS Bit from 0 to 30 00H to 1EH EOS byte o cooooooo oh Send EOI at end of Write Yes Riding 32 to the primary address forms the Listen Address LA Endble Repeat Addressing Yes Riding 64 to the primary address forms the Talk Address TA EXAMPLE Selecting a primary address of 10 yields the following 4 10 32 42 Listen address 10 64 74 Talk address Fi Help F6 set Value F9 Esc Return to Map Ctl PqoJp PgIn Next Prev Board IBCONF EXE eps Figure 6 3 Typical National Instruments GPIB Configuration from IBCONF EXE Computer Interface Operation Lake Shore Model 480 Fluxmeter User s Manual Table 6 3 Quick Basic IEEE 488 Interface Program IEEEEXAM BAS EXAMPLE PROGRAM FOR IEEE 488 INTERFACE This program works with QuickBasic 4 0 4 5 on an IBM PC or compatible The example requires a properly configured National Instruments GPIB PC2 card The REM SINCLUDE statement is necessary along with a correct path to the file QBDECL BAS CONFIG SYS must call GPIB COM created by IBCONF EXE prior to run
41. are addressed commands The Model 480 supports a variety of Device Specific commands to program instruments remotely from a digital computer and to transfer measurements to the computer Most Device Specific Commands perform functions also performed from the front panel This section discusses Common and Device Specific commands Device Specific Commands consist of Interface Display Channel and Control Process commands Refer to Paragraph 6 3 for a list of all Model 480 interface and device specific commands 6 1 3 Status Registers There are two status registers the Status Byte Register described in Paragraph 6 1 3 1 and the Standard Event Status Register in Paragraph 6 1 3 2 6 1 3 1 Status Byte Register and Service Request Enable Register The Status Byte Register consists of one data byte containing seven bits of information about Model 480 status STATUS BYTE REGISTER FORMAT Bie e aa Bag E ME E A GI Weighting 128 64 32 16 8 DEA el Bit Name If the Service Request is enabled setting any of these bits causes the Model 480 to pull the SRQ management low to signal the BUS CONTROLLER These bits reset to zero upon a serial poll of the Status Byte Register Inhibit or enable these reports by turning their corresponding bits off or on in the Service Request Enable Register The SRE command sets the bits Setting a bit in the Service Request Enable Register enables that function Refer to the SRE command Service Re
42. by applicable law neither Lake Shore nor any of its subsidiaries affiliates or suppliers will be held liable for direct special incidental consequential 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 limitations 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 statement 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
43. code Private Sub Form_Load Add the code to this subroutine as shown in Table 6 6 d Double Click on the Timer control Add code segment under Private Sub Timer1_Timer as shown in Table 6 6 e Make adjustments to code if different Com port settings are being used 13 Save the program 14 Run the program The program should resemble the following 5 Serial Interface Program Type exit to end program Commengd Response m l ES 15 Type in a command or query in the Command box as described in Paragraph 6 2 3 3 16 Press Enter or select the Send button with the mouse to send command 17 Type Exit and press Enter to quit 6 16 Computer Interface Operation Lake Shore Model 480 Fluxmeter User s Manual Table 6 6 Visual Basic Serial Interface Program Public gSend As Boolean Global used for Send button state Private Sub cmdSend Click gSend True End Sub Routine to handle Send button press Set Flag to True Private Sub Form Load Dim strReturn As String Dim strHold As String Dim Term As String Dim ZeroCount As Integer Dim strCommand As String frmSerial Show Term Chr 13 Chr 10 ZeroCount 0 strReturn strHold If frmSerial MSComml PortOpen True Then frmSerial MSComml PortOpen False End If frmSerial MSComm1 CommPort 1 frmSerial MSComml Settings 9600 0 7 1 frmSerial MSComml1 InputLen 1 frmSerial MSComm1 PortOpen Tru
44. designed so the instantaneous coil voltage does not exceed the rated input voltage of the integrator Magnetizers can create very large instantaneous coil voltages because their flux changes so quickly d dt is large It is not difficult to calculate the maximum instantaneous coil voltage if the maximum rate of field change is known Using the equations Heel d B 9 dt and A gives us Vag MA dt If Veou is in volts N in turns A in cm2 B in gauss and t in seconds Veo NA dB dt 108 A magnetizer of modest energy can achieve a flux density change dB of 3 T 30 000 G in 1 ms dt If a coil of 1 cm area A and 100 turns N is in that field the voltage generated during firing is 30 000 0 00185 Desch ku 307 Note that high energy magnetizers with faster rise times can produce dangerous voltages with many fewer turns Coil Size Application often dictates coil size Some low field coils may be several feet in diameter to contain enough changing flux for a measurable coil voltage Coils for high gradient fields are small as possible so the coil area does not exceed the uniform field area Coil size often limits the number of turns and therefore the sensitivity Coils of any length can be used with a fluxmeter from a single turn to a long solenoid In practice the coil should be limited in length so the same flux lines link all turns Substantial error occurs when the flux lines curve out of the coil and link only
45. disabled for Lake Shore probes because they are calibrated at the factory Coil calibration is disabled for if the instrument is operating in integrator units because no calibration of the coil is necessary As described below the feature will only calculate one parameter for each type of magnetic measurement More than one calibration can be done on the same coil but each calibration is done separately Coil resistance should be entered before a coil is calibrated if its resistance is meaningful Measurement Units Parameter Flux VS Turns N Wb Turns N Mx Turns N Flux Density B Area Turns AN T Area Turns AN Moment Wb cm Helmholtz Constant Potential A Potential Constant Before using Coil Calibration Turn the instrument on and allow it to warm up Measure the DC coil resistance and enter it with Coil Setup if necessary Choose the desired measurement units If the existing value of the coil parameter being calibrated is interfering with the measurement resolution set it to 1 using Coil Setup Make several measurements of the test magnet to assure repeatability An improper range setting or excess drift can cause difficulty in repeating measurements Calibrating a Coil Begin the coil calibration sequence by resetting the reading with the Reading Reset key or the peak hold value with the Peak Reset key Make a measurement of the sample magnet or place the coil in a known magnetic environment Press the C
46. ect Coil l The numbers 01 thru 10 correspond to instrument memory locations for coil parameters User indicates that parameters have been changed since the last time the coil was selected from memory Use the a or v keys to cycle thru the available selections Press the Enter key to make a selection or press the Escape key to cancel and return to the normal display NOTE Probe will be seen when the Model 480 detects a probe attached to the instrument When a probe is attached instrument memory locations cannot be selected 5 8 Advanced Operation 5 7 5 8 Lake Shore Model 480 Fluxmeter User s Manual RANGE SELECTION Range selection is difficult to define for the Model 480 because of its different measurement units but the operation is simple The input range can be increased to measure large signals or decreased to measure smaller signals with better resolution All available ranges are accessible during range selection At that time the full scale range and reading resolution will be shown Full scale range and resolution are listed for V s units in the Specifications detailed on Page 1 2 There are two decade range selections available for DC and DC peak measurements Input resistance Paragraph 5 3 1 can be changed to allow a third decade of measurement range Coil construction can also be changed to alter the range boundaries in magnetic units The DC range setting is stored separately from the AC rang
47. measured in oersteds Oe In the SI system it is measured in amps per meter A m 10e 79 58 Afm Flux density and magnetic field strength are related by the permeability ul of the magnetic medium B pH Permeability is a measure of how well a material makes a path for flux lines The confusion of flux density and magnetic field strength is also related to permeability In the CGS system the permeability of air of vacuum is 1 Therefore 1 G 1 Oe or B Hin air Many people incorrectly assume therefore that in the CGS system B H at all times Adding to the confusion in the SI system permeability of air is not 1 so B is not equal to H even in air 2 5 MAGNETIC MOMENT OVERVIEW 2 5 1 2 5 2 What is Magnetic Moment Magnetic moment m measures the magnetic field strength H produced at points in space by a plane current loop or a magnetized body The CGS system measures moment in emu and defines it as the pole strength of a permanent magnet multiplied by the distance between the poles This is sometimes called dipole moment j Wb m The SI system measures moment in amps times square meters Am and defines it as the current in a conducting loop times the area of the loop or Lem 10 Am Magnetic moment is measured to determine various performance factors of permanent magnets For example magnetization M can be calculated by dividing magnetic moment by the volume of a magnet A Helmholtz coil and fluxmeter provide a
48. of A m or cgs units of oersted magnetic flux density B Also referred to as magnetic induction This is the net magnetic response of a medium to an applied field H The relationship is given by the following equation B uo H M for SI and B H 47M for cgs where H magnetic field strength M magnetization and uo permeability of free space 41 x 107 H m magnetic hysteresis The property of a magnetic material where the magnetic induction B for a given magnetic field strength H depends upon the past history of the samples magnetization magnetic induction B See magnetic flux density magnetic moment m This is the fundamental magnetic property measured with dc magnetic measurements systems such as a vibrating sample magnetometer extraction magnetometer SQUID magnetometer etc The exact technical definition relates to the torque exerted on a magnetized sample when placed in a magnetic field Note that the moment is a total attribute of a sample and alone does not necessarily supply sufficient information in understanding material properties A small highly magnetic sample can have exactly the same moment as a larger weakly magnetic sample see Magnetization Measured in SI units as A m and in cgs units as emu 1 emu 10 A m magnetic scalar potential The work which must be done against a magnetic field to bring a magnetic pole of unit strength from a reference point usually at infinity to the point in question Also kn
49. operation the instrument should be allowed to idle in DC mode when not in use and switched to DC Peak before being used The DriftTrak algorithm continuously monitors changes in the fluxmeter reading If the changes are large the algorithm assumes an actual change in measured field and shuts itself off for a short time When shut off DriftTrak will not affect active measurements If changes are small the algorithm assumes the fluxmeter is idle and any changes in reading are caused by drift During this time new values for the drift compensation DACs are calculated and stored The limit separating large and small changes is called a threshold and can be changed by the user for different applications and system noise levels It is important to understand that idle time is necessary for DriftTrak operation The algorithm becomes active if the change threshold is not exceeded for only a few seconds but it can take a minute or more for the calculated DAC setting to have an impact on drift performance Best performance will be achieved if the algorithm has 10 to 20 minutes to operate on an idle instrument The default settings for the instrument are DriftTrak on and a change threshold of 200 pV s min The recommended operating range for the threshold is 100 to 1000 uV s min and it can only be set in uV s min Lower settings are for quiet systems measuring slow changes in field Higher settings are for noisy systems measuring fast changes in field Adva
50. others have simply ignored it During instrument factory calibration readings are taken 1 to 2 seconds after any signal transition DC Peak AC and AC Peak readings do not suffer from this anomaly Magnetic Measurement Overview 2 3 2 1 7 2 1 7 1 Lake Shore Model 480 Fluxmeter User s Manual Analog Versus Digital Integrators Most of the integrator discussion in this manual is based on analog integrators Analog integrators are made with analog amplifiers resistors and capacitors Digital integrators approximate the action of analog integrators by combining voltage sampling and software integration algorithms There are advantages and disadvantages to both types of integrators The performance of digital circuitry continues to improve and the price continues to decline There are now few analog functions that cannot be approximated digitally Digital circuits are generally smaller and have fewer discrete components Their behavior is more repeatable with fewer calibrations Digital integration is likely the best choice to integrate predictable and well behaved signals Analog circuit technology is not standing still Fast changing high voltage or very low voltage signals are still integrated most accurately with analog integrators The general purpose Model 480 uses an analog integrator The instrument must perform well with any type of input signal The digital circuitry surrounding the analog integrator offers most of the advantages of
51. part of the turns The fluxmeter assumes all of the turns see the same flux Some coil geometries count on coil length to achieve specific measurement goals Coil length can help eliminate the effect of field non uniformity Paragraph 2 2 6 or measure magnetic potential Paragraph 2 6 Coil Resistance Coil resistance is sometimes overlooked because it does not appear in ideal equations for a coil or integrator but it can limit sensitivity Wire does have resistance and with enough turns it can become applicable Coil resistance must be accounted for when it is a meaningful percentage of the integrator input resistance R COIL COIL C 480 2 4 eps Magnetic Measurement Overview 2 7 Lake Shore Model 480 Fluxmeter User s Manual Coil Resistance Continued 2 2 4 2 2 5 The DC resistance of the coil must be added to the input resistance of the integrator to get an accurate volt second reading The expression for a voltage integrator becomes 1 Vo o LR R Ta v di Manufacturers specify integrator resistance for a fluxmeter typically between 1 kQ to 100 kQ Table 2 1 lists examples of copper wire resistance Table 2 1 Examples of Copper Wire Resistance AWG Annealed O D inches Ohms per 1 000 feet Copper at 20 C at 20 C 0 0031 1079 2 To calculate the percentage error in reading due to coil resistance Error Ro x100 R R in coil As an example if Rin 100 KQ and Reoi 1 KQ an error of 1
52. per current unit rather than the coil constant needed Given below in Paragraphs 2 5 3 1 and 2 are methods of measuring values which can be used to calculate the constant Paragraph 2 5 3 3 gives formulas for calculating the coil constant when coil sensitivity is given 2 5 3 1 By Measurement of Amperes per Gauss A gaussmeter and current source are required In free air one gauss one oersted Directly measure the current required amperes to produce a certain magnetic field gauss oersted In the calculation of the coil constant we have to convert oersteds to amperes centimeter The Lake Shore 480 fluxmeter accepts a value for coil constant only in centimeters COIL CONSTANT K I H amperes oersted amperes amperes cm cm units only Example A common Helmholtz coil might require 1 ampere to generate a 30 gauss field Thus K 1 ampere 30 oersteds 1 ampere 30 x 0 796 A cm 0 0419 cm 2 5 3 2 By Measurement of Amperes per Tesla Most of the comments above hold except that the relationship between flux density B and magnetic field strength H in the SI system is not as simple as in the cgs system H B ue where un 4r x 107 for H A m or H B po where un 4x x 10 for H A cm COIL CONSTANT K I H amperes amperes cm cm units only Example The same coil as above requires 1 ampere to generate a 3 mT millitesla field Thus H 0 003 41 x 10 5 23 87 A cm K 1 ampere 23 87 A cm 0 0419 cm 2 5 3 3 Conv
53. results If Rin 10 KQ and Reoi 1 KQO an error of 9 1 results if coil resistance is not taken into account Coil Temperature Coefficient Since coil resistance is temperature dependent care must be taken when large temperature changes are expected The temperature coefficient of resistance for copper magnet wire is 0 4 C 0 22 F For example a temperature increase of 10 C in a 1000 coil causes a resistance increase of 40 Q to 1040 If Rin 10 KQO the attenuation from Reo in the Paragraph 2 2 3 example changes from 9 1 to 9 43 Coil Orientation Coil voltage is related to the number of changing flux lines passing through the center of the coil The flux measured is a true indication of the number of lines passing through The angle of the flux lines passing through the coil does not matter that is not to say that the orientation of a coil to a magnet does not matter Changing coil orientation relative to a magnet often changes the number of flux lines that pass through the coil Orient the coil perpendicular to the flux lines for the most repeatable measurements 2 8 Magnetic Measurement Overview 2 2 6 2 2 7 2 2 8 2 2 9 Lake Shore Model 480 Fluxmeter User s Manual Field Uniformity Flux measurement is a true indication of lines of flux passing through a coil Field uniformity does not affect flux measurement but other magnetic measurements such as flux density assume uniform flux over the coil ar
54. the a or v keys to select the range appropriate to your measurement 11 Press the Reading Reset key 12 If the instrument has just been turned on allow it to warm up for at least 10 minutes before proceeding Otherwise proceed to Step 13 13 Press the Drift Adjust key Use the a or v keys until Begin Auto Adjust is displayed Press the Enter key You will see the following message ADJUSTING DRIFT For 25 Seconds 14 Make the test measurement 15 If the reading appears to be drifting refer to the Drift Adjust discussion in Paragraph 5 9 4 8 Basic Operation Lake Shore Model 480 Fluxmeter User s Manual CHAPTER 5 ADVANCED OPERATION 5 0 GENERAL This chapter provides advance operation instructions for the Lake Shore Model 480 Fluxmeter Units selection is described in Paragraph 5 1 Coil parameters in Paragraph 5 2 Coil setup in Paragraph 5 3 Making measurements in percent in Paragraph 5 4 Coil calibration in Paragraph 5 5 Coil select and parameter storage in Paragraph 5 6 range selection in Paragraph 5 7 Reading reset in Paragraph 5 8 Drift adjustment in Paragraph 5 9 DC and AC measurement modes in Paragraph 5 10 Peak hold and peak reset in Paragraph 5 11 Filter operation in Paragraph 5 12 Display resolution in Paragraph 5 13 Alarm and relay operation in Paragraph 5 14 Analog outputs in Paragraph 5 15 External reset in Paragraph 5 16 Locking and unlocking the keypad in Paragraph 5 1
55. the digital voltmeter is used to actually measure the voltage at the Model 480 terminals Used in DC calibrations A D Reference Voltages NOTE The adjustment of the following voltage trimpots voids any existing calibration data of the instrument and requires completion of the entire calibration procedure 1 Set the Model 480 to AC non peak operation 30 mV s range 100 kQ input resistance no input signal 2 Measure the 2 5 VDC at pin U27 12 referenced to signal ground test point TP5 and adjust R69 for 2 5 VDC 10 uV 3 Measure the 2 5 VDC test point TP13 referenced to signal ground test point TP5 and adjust R81 for 2 5 VDC 10 pV Initialize for Calibration NOTE This step replaces all existing calibration data with nominal starting values 1 Send CALCLR command to the Model 480 via the computer interface 8 10 Service and Calibration Lake Shore Model 480 Fluxmeter User s Manual 8 9 4 AC Peak Offset 1 Short the input terminals of the Model 480 2 Set Model 480 to AC Dual Peak operation 100 kQ Input Resistance 30 mV s range 3 Set Model 480 units to Volts available only through computer interface send UNITS 0 over the computer interface 4 Reset and read offsets directly as voltages on the Model 480 5 Take 10 readings 6 Average all positive readings average all negative readings 7 Send positive average reading to Range V
56. the upper one is recognized under or consistent with Sl and is based on the definition B uo H M where to po 4r x 10 7H m The lower one is not recognized under SI and is based on the definition B poH J where the symbol is often used in place of J 1 gauss 105 gamma y Both oersted and gauss are expressed as cm g s in terms of base units A m was often expressed as ampere turn per meter when used for magnetic field strength Magnetic moment per unit volume The designation emu is not a unit Recognized under Sl even though based on the definition B poH J Refer to note c Ur W o 1 x all in SI uris equal to Gaussian p B H and uo H have SI units J m M H and B H 4x have Gaussian units erg cm R B Goldfarb and F R Fickett U S Department of Commerce National Bureau of Standards Bolder Colorado 80303 March 1985 NBS Special Publication 696 For sale by the Superintendent of Documents U S Government Printing Office Washington D C 20402 Reference Information B 1 Lake Shore Model 480 Fluxmeter User s Manual Table B 2 Recommended SI Values for Physical Constants lle of Vacuum oa 4r x 107 Hm a a a 0 0073 Fine Structure Constant u0ce2 2h 137 0360 Elementary Charge e 16022x 10 19C h 6 6262 x 1034 J Hz Plank s Constant h h 2n 1 0546 x 10 Js Avogadro s Constant 6 0220 x 10 mol Atomic Mass Unit 1 u 10 kg mol t Na 1 6605 x 10 kg oar me Bok
57. this product at the time of shipment are traceable to the United States National Institute of Standards and Technology NIST formerly known as the National Bureau of Standards NBS FIRMWARE LIMITATIONS Lake Shore has worked to ensure that the Model 480 firmware is as free of errors as possible and that the results you obtain from the instrument are accurate and reliable However 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 international 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 480 firmware as phys
58. 120V US NEMA 5 15 3 220V EU CEE 7 7 4 240V EU CEE 7 7 5 240V UK BS 1363 6 240V Swiss SEV 1011 7 220V China GB 1002 7 1 ACCESSORIES Accessories are devices that perform a secondary duty as an aid or refinement to the primary unit Accessories available for the Model 480 Fluxmeter are listed as follows Model Number Description 106 739 Terminal Block Mating Connector Eight pin quantity of two 4004 IEEE 488 Interface Cable Connects Model 480 to Customer supplied computer with IEEE 488 Interface Cable is 1 meter 3 3 feet long 4030 XX Probe Stand This moveable probe stand consists of a 30 mm square post mounted on a 180 x 130 x 22 5 mm thick base plate A probe holder is integrated into the stand The holder can be moved up or down and fixed at any angle and location along the post Two models are available as follows Consult factory for other post heights 4030 12 Probe stand with 12 inch tall post and probe holder to accept 3 8 inch diameter probe handle 4030 24 Probe stand with 24 inch tall post and probe holder to accept 3 8 inch diameter probe handle FCBL 6 User Programmable Coil Interconnect Cable Has an internal PROM that is programmable from the Model 480 front panel 1 8 meters 6 feet long Refer to Accessories Coils and Probes 7 1 Lake Shore Model 480 Fluxmeter User s Manual Paragraph 3 5 for installation Refer to Paragraph 5 6 2 for programming FH XX Helmholtz Coils Thr
59. 4 Relays and Analog Signals Terminal Block 8 5 8 5 SERIAL WO Connector Details 8 5 8 6 IEEE 488 Rear Panel Connector Details 0c ccccceceeseeceeeeeceeeeeeeeeeeeeeecaeeesaaeeeeaeeseeeesaeeesaeeseeees 8 7 8 7 Location of Operating Software EPROM onccccccccocononononononcnnnnncnnnnnn nan nc cnn ncn narran rra rca 8 9 LIST OF TABLES Table No Title Page 2 1 Examples of Copper Wire Resistance ooonncccincccninncnnocnnnccccocccnnonn nan n cnn cnc 2 8 3 1 Sample AC Line Input List 200 000 cceeeesceceeeeeceeeeeeeaeeeeneeceaeeeeaaeseeaaeegaeeeceaeeesaaesgeeeeseeeesaeeeeaaeseeneeee 3 3 5 1 Units and Associated Coil Parameters c occoincccnnccinoncnnnoccconcnnnnnnnn no nn nan c rra 5 1 5 2 Default alles a dana 5 22 6 1 IEEE 488 Interface Program Control Properties oooonncccinnccnnccnnnccnonccnconcccnnrnnn nara nn cnc 6 8 6 2 Visual Basic IEEE 488 Interface Program oooonoccccnonicccinnnoccconononccnnnnorccnn anna rn 6 9 6 3 Quick Basic IEEE 488 Interface Program 6 12 6 4 Serial Interface Gpechications cr 6 14 6 5 Serial Interface Program Control Properties cccecececeeeeeeeeeeeeeeeseeeeecaeeesaaeeeeeeeseaeeesaaeeseaaeeeneees 6 16 6 6 Visual Basic Serial Interface Program cccccccseceeseeeeeeeeeaeeeeeaeceeeeecaeeeeaaeeseaeeseneeeseaeeetaeeseaeeeeaes 6 17 6 7 Quick Basic Serial Interface Program 6 18 8 1 AG Calibration le 8 11 8 2 DG Calibration E Le ia 8 12 Table of Contents Lake Shore Model 480 Fluxmeter Use
60. 7 And resetting to default values in Paragraph 5 18 5 1 UNITS SELECTION Units selection is an important step in operating a fluxmeter Measurement results have a different meaning depending on which units are chosen Different coil parameters are needed and operating ranges change There may be only one practical units choice for a given application The units available in the Model 480 are summarized in Table 5 1 The table indicates which coil parameters are needed for each unit selection Unmarked parameters are ignored Units grouped as integrator flux or flux density share the same parameter requirements The units selected can be used for DC DC Peak AC and AC Peak measurements Alarm setpoint values can be set in any units The corrected analog output can be scaled to work with any units Once units are selected proceed to the coil setup function to enter the required parameters Table 5 1 Units and Associated Coil Parameters Coil Area Potential Helmholtz Percent Measurement Units Resistanc Turns N Turns Constant Constant Scale System Equation e Reoil A N Pc Hc Factor C Integrator Ves a a Primary WbN m WbN V S MxN e MxN 10 V s Flux i Vesp E o S V sod V s N Wb a o Sl Wb WbN N Mx a e CGS Mx MxN N Flux G E o CGS G Mx cm Density B T m e SI T Wb m Potential A a o SI z Moment Wbecm a o SI Percent a o S Will be calculated by the instrument if turns N and area A
61. 80 Fluxmeter are detailed in Figures 8 2 thru 8 6 Additional details for the IEEE 488 connector and various external serial cables are provided in Paragraphs 8 5 1 and 8 5 2 respectively COIL INPUT DESCRIPTION C 480 8 2 wmf HI Input Red Banana Jack LO Input Black Banana Jack Figure 8 2 COIL INPUT Connector Details PROBE INPUT C 480 8 3 cvs PIN DESCRIPTION Probe Coil Input Hi Analog Signal No Connection No Connection No Connection No Connection No Connection No Connection No Connection Probe Coil Input Lo Analog Signal Ground No Connection Digital Ground 5 Volts Power Output To Probe EEPROM EECLK Output To Probe EEPROM EEDATA Serial Input From Probe EEPROM No Connection OONDOOARWND Figure 8 3 PROBE INPUT Connector Details 8 4 Service and Calibration Lake Shore Model 480 Fluxmeter User s Manual Slides into slots at rear of Model 480 Use screwdriver to lock or unlock wires Terminal Block Connector Lake Shore P N 106 739 Quantity 2 Insert wire into slot The terminal block plugged into the top slot has pin numbers 1 8 while the terminal block in the bottom slot has pin numbers 9 16 PIN DESCRIPTION High Alarm N O High Alarm Common High Alarm N C Low Alarm N O Low Alarm Common Low Alarm N C Monitor Output Signal Monitor Output Ground Middle Alarm N O Middle Alarm Common Middle Alarm N C External Reset Gro
62. A The CGS system measures flux density in gauss G where 1 G 1 Mx cm The SI system measures flux density in tesla T where 1 T 1 Wb m Flux density is important when magnet systems concentrate flux lines into a specific area like the pole pieces in an electromagnet Forces generated on current carrying wires like those in a motor armature are proportional to flux density Saturation of magnetic core material is also a function of flux density Flux density is often the desired measurement quantity when using a fluxmeter In a uniform field flux density can be calculated by dividing measured flux by the area of the search coil This can be done with a fluxmeter as long as the lines of flux are perpendicular to the plane of a flat coil or along the axis of a longer coil Hall effect gaussmeters make similar measurements Fluxmeters can also measure flux density inside a piece of magnetic material In this case coils are wrapped tightly around a material core to ensure the area of the coil is the same as the cross section of the core Gaussmeters cannot make this type of measurement 2 10 Magnetic Measurement Overview 2 4 2 Lake Shore Model 480 Fluxmeter User s Manual How Flux Density B Differs from Magnetic Field Strength H Flux density is often confused with magnetic field strength Magnetic field strength is a measure of the force producing flux lines The symbol for magnetic field strength is H In the CGS system it is
63. Add two TextBox controls to the form c Add one CommandButton control to the form d Add one Timer control to the form 8 On the View Menu select Properties Window 9 Inthe Properties window use the dropdown list to select between the different controls of the current project aPrwonn N o Label Command Label3 Label 10 Set the properties of the controls as defined in Table 6 5 11 Save the program Computer Interface Operation 6 15 Lake Shore Model 480 Fluxmeter User s Manual Table 6 5 Serial Interface Program Control Properties Current Name Property New Value Labeli Name lblExitProgram Caption Type exit to end program Label2 Name lbICommand Caption Command Name lbIResponse Panes Caption Response Texti Name txtCommand Text lt blank gt Name txtResponse Texte Text lt blank gt Name cmdSend Command1 Caption Send Default True Formi Name frmSerial Caption Serial Interface Program Timert Enabled False Interval 10 12 Add code provided in Table 6 6 a Inthe Code Editor window under the Object dropdown list select General Add the statement Public gSend as Boolean b Double Click on cmdSend Add code segment under Private Sub cmdSend_Click as shown in Table 6 6 c Inthe Code Editor window under the Object dropdown list select Form Make sure the Procedure dropdown list is set at Load The Code window should have written the segment of
64. C up to 6 digits and a decimal point in exponential form Set Fine Drift Adjustment DAC Value DACFINE nnn nnnE nn Nothing Sets the percentage of full scale of the fine drift adjustment DAC Enter up to 6 digits and a decimal point in exponential form Valid values are from 100 to 100 Query Fine Drift Adjustment DAC Value DACFINE nnn nnnE tnn Returns the percentage of full scale of the fine drift adjustment DAC up to 6 digits anda decimal point in exponential form Set DC Resolution High Low DCRES Nothing Sets the DC Resolution of the unit where 0 5 digits and 1 4 digits Query DC Resolution High Low DCRES 0 or 1 Format n term Returns the DC Resolution of the unit where 0 5 digits and 1 4 digits Computer Interface Operation Lake Shore Model 480 Fluxmeter User s Manual DFLT 99 Set To Factory Defaults Input DFLT 99 Returned Nothing Remarks Used to reset the instrument to default values and to clear the user entered coil parameters Does not clear instrument calibration DRAUTO Initiate Auto Drift Correction Input DRAUTO Returned Nothing Remarks Starts an Auto Drift Correction Sets Fine DAC to 0 and adjusts Coarse DAC This process takes approximately 25 seconds to complete DRTHR Set DriftTrak Threshold Level Input DRTHR nnnn Returned Nothing Remarks Sets the threshold level of the DriftTrak function This is the rate of change that will cause the Dri
65. Directives and Standards Application of Council Directives mommmm 2006 95 EC LVD 2004 108 EC EMC Standards to which Conformity is declared EN 61010 1 2010 Overvoltage Il Pollution Degree 2 EN 61326 1 2013 Class A Annex B Model NUMDE EE 480 2 f J Def Se JO 20 4 Scott Ayer T Director of Quality and Compliance Position Lake Shore Model 480 Fluxmeter User s Manual Electromagnetic Compatibility EMC for the Model 480 Fluxmeter Electromagnetic Compatibility EMC of electronic equipment is a growing concern worldwide Emissions of and immunity to electromagnetic interference is now part of the design and manufacture of most electronics To qualify for the CE Mark the Model 480 meets or exceeds the generic requirements of the European EMC Directive 89 336 EEC as a CLASS A product 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 followed there should be no degradation in EMC performance Pay special attention to instrument cabling Improperly installed cabling may defeat even the best EMC protection
66. ECT AND PARAMETER STORAGE coocccccocccoconcnonnncnncnnnnnanannnnnnncn cnn nn naar nn nannccnnnes 5 7 5 6 1 Storing New Coil Parameters into Instrument Memory oooocccinccconocononaccnoncccnnnnnanonanana cnn 5 8 5 6 2 Storing New Coil Parameters into Probe Memory c oocnccccincccnocccononanonononanccnannnna nn nnnanc cnn 5 8 5 6 3 Selecting Saved Coil Parameters A 5 8 ii Table of Contents Lake Shore Model 480 Fluxmeter User s Manual TABLE OF CONTENTS Continued Chapter Paragraph Title Page 5 7 RANGE SELEGTION dee cate viet att ie ata itl tat 5 9 5 8 READING RESE Tornar eet ea dl eee needa 5 9 5 9 DRIFT ADJUSTMENT aiena anaana da 5 10 5 9 1 Automatic Drift Adiustment A 5 10 5 9 2 Manual Drift Adjustment A 5 11 5 9 3 Blue 5 11 5 10 DC AND AC MEASUREMENT MODERN 5 12 5 10 1 DC Measurement Mode 5 12 5 10 2 AC Measurement Mode 5 13 5 11 PEAK HOLD AND PEAK RESE Taieri e a ia aa e aA a nn nana c cnn EEA aan 5 14 5 11 1 Peak Hold in DC Mode coooooccocccccoccccconcnononcnanocononcnnnnnnnn nn nn nan n cra rca nn ran c nan cnr anna nnnn nn nnnnccnns 5 14 5 11 2 Peak Hold in AC Modein ina a a a aa E A r anna rca 5 14 5 11 3 Activating Peak Mode rrira Ra T E E RA 5 14 5 11 4 Peak Rosolo oninia n a 5 15 5 11 5 Choosing Positive Negative or Both Peaks oooonnnocinnccnnccnnnnonncocnnonccccnnncnnnnnnnnnnnnann cnn 5 15 5 12 FILTER ta A o Ad E NEE E 5 15 5 13 DISPLAY RESOLUTION 500 ddr bai 5 16 5 14 ALARM AND RELAY OPERATION nn nnnn cra nn nn anna nnnn nn nnn
67. EE Address Configure Serial Interface Baud Rate Query Serial Interface Baud Rate Set EOI Parameter Query EOI Parameter Configure Remote Interface Mode Query Remote Interface Mode Set Terminating Character Query Terminating Character Device Specific Commands Configure AC DC Reading Parameter 6 23 Query AC DC Reading Parameter ACDC ACDC ALARM ALARM ALMB ALMB ALMH ALMH ALMIO ALMIO ALML ALML ALMS ANOCON ANOCON ANOH ANOH ANOL ANOL ANOM ANOM BRIGT BRIGT CODE CODE COILA COILA COILAN COILAN COILCAL COILINR COILINR COILKH Configure Alarm Function Off On Query Alarm Function Off On Configure Audible Alarm Beeper Configure Audible Alarm Beeper Set Alarm High Point Value Query Alarm High Point Value Configure Alarm Trigger Outside Inside 6 24 Query Alarm Trigger Outside Inside Set Alarm Low Point Value Query Alarm Low Point Value Query Alarm Status Set Analog Out Control Value Query Analog Out Control Value Set Analog Out High Point Value Query Analog Out High Point Value Set Analog Out Low Point Value Query Analog Out Low Point Value Configure Analog Out Mode Query Analog Out Mode Set Front Panel Display Brightness Query Front Panel Display Brightness Set Keyboard Lock Code Query Keyboard Lock Code Set Coil Area Query Coil Area Set Coil Area Turns Query Coil Area Turns Initiate Coil Calibration Configure Input Resistance Query Input Resistance Set Helmholtz Coil
68. ION WARNING Many probes used with the fluxmeter have conductive parts Never probe near exposed live voltage Personal injury and damage to the instrument may result CAUTION Always turn off the instrument before making any rear panel Probe Input connections Lake Shore coils and probes plug into the 15 pin D type connector on the Model 480 rear panel Turn the instrument off before attaching a probe See Figure 8 3 for pin definitions When power is turned on the instrument reads coil parameters from probe memory The probe is ready to use No parameters need to be entered into the Model 480 Drift must still be adjusted as described in Paragraph 5 9 Attachment To A Non Lake Shore Coil The FCBL 6 has a 15 pin D connector on one end for direct attachment to the PROBE INPUT on the back panel of the Model 480 Fluxmeter Two tinned wires are provided for the coil connection The coil leads may be soldered directly to these wires If the coil has a banana receptacle on it a screw contact banana plug is supplied with the FCBL 6 for attachment 5 Foot Cable to Fluxmeter Green Wire Red Wire F FCBL 6 eps Figure 3 3 Model FCBL 6 User Programmable Cable Accessory Instrument Setup 3 3 Lake Shore Model 480 Fluxmeter User s Manual Attachment to a Non Lake Shore Coil Continued 3 6 3 6 1 3 6 2 3 6 3 3 6 4 If the polarity of the signal from the coil is known the red wire should be attached to the lead su
69. Manual On 2 Automatic RELAYH Query High Relay Function Input RELAYH Returned 0 1 or 2 Format n term Remarks Returns the high relay function 0 Manual Off 1 Manual On 2 Automatic RELAYL Configure Low Relay Function Input RELAYL lt mode gt Returned Nothing Remarks Configures the low relay function 0 Manual Off 1 Manual On 2 Automatic RELAYL Query Low Relay Function Input RELAYL Returned 0 1 or 2 Format n term Remarks Returns the low relay function O Manual Off 1 Manual On 2 Automatic RELAYM Configure Middle Relay Function Input RELAYM lt mode gt Returned Nothing Remarks Configures the middle relay function O Manual Off 1 Manual On 2 Automatic RELAYM Query Middle Relay Function Input RELAYM Returned 0 1 or 2 Format n term Remarks Returns the middle relay function 0 Manual Off 1 Manual On 2 Automatic RNGAC Configure AC Range Parameter Input RNGAC lt range gt Returned Nothing Remarks Configures the Model 480 AC range 0 30 mV s 1 3 mV s 2 300 uV s 3 30 uV s 6 34 Computer Interface Operation RNGAC Input Returned Remarks RNGDC Input Returned Remarks RNGDC Input Returned Remarks RNGMX Input Returned Remarks TERM Input Returned Remarks TERM Input Returned Remarks UNITS Input Returned Remarks UNITS Input Returned Remarks Lake Shor
70. N Each cable is usable only with a specific coil When users supply the connecting cable the input resistance listed is only suggested However when a Lake Shore cable containing the pre programmed PROM is used the input channel indicated is the preferred channel for that coil and that channel will automatically be selected when the PROM data is loaded Model Number FH 2 5 FH 6 FH 12 Inside Diameter 2 5 inches 6 inches 12 inches Coil Resistance Approx 35 Q 1100 1400 Operating Temp Range 10 to 40 C Coil Constant 0 013 Wb cm V s 0 016 Wb cm V s 0 047 Wb cm V s Input Resistance 10 kQ 100 kQ 10 kQ 100 kQ 10 KQ 100 kQ Ranges tappron 390 uWb cm 3 9 mWb cm 480 uWb cm 4 8 mWb cm 1 4 mWb cm 14 mWb cm 39 uWb cm 390 uWb cm 48uWb cm 480 uWb cm 140 uWb cm 1 4 mWb cm 1 25 WIDE 1 00 HIGH OPENING THRU BOTH SIDES BANANA JACKS Figure 7 3 Model FH 2 5 Helmholtz Coil P 480 7 3 bmp Accessories Coils and Probes 7 5 Lake Shore Model 480 Fluxmeter User s Manual P 480 7 4 bmp P 480 7 5 bmp Figure 7 5 Model FH 12 Helmholtz Coil 7 6 Accessories Coils and Probes 7 4 Lake Shore Model 480 Fluxmeter User s Manual REFERENCE MAGNETS Magnetic reference standards containing highly stable permanent magnets have been in use for many years The highest quality units are usually shielded from external magnetic effects and use Aln
71. NAL INPUT The Model 480 terminal block has a connection for an optional logic input It is commonly used to monitor status of a thermostat or proximity switch The Model 480 monitors the logic level of this input which can then be read over computer interface The input is TTL compatible A logic low will produce a 0 interface response and a logic high will produce a 1 interface response The signal is internally pulled up to allow operation with a simple switch closure between Pins 14 and 13 The OPTIN query can be used with IEEE 488 or RS 232C Computer Interface to verify the status of the input Allow 100 ms for an input status change to appear in the interface response LOCKING AND UNLOCKING THE KEYPAD The Model 480 front panel keypad can be locked to prevent unauthorized changes to settings To lock the keypad press and hold the Enter key until the following screen is displayed Enter Code T0 Lock Keyrad Enter the 3 digit lock code default 123 Upon entry of the third digit the display reverts to the normal display and the keypad locks After locking any attempt to change settings displays the Locked message shown as follows Lock ect To unlock the keypad press and hold the Enter key until the following screen is displayed Enter Code T0 Urn ock Kesrad Enter the lock code again Upon entry of the third digit the display reverts to the normal display and the keypad
72. NG ON POWER EEN 4 1 4 2 DISPLAY DEFINITIONesractiti teil eege 4 1 4 3 READING FORMAT tutor est Mee el s alioli 4 2 4 4 KEY PADADEFINITION ivi atras 4 2 4 5 GENERAL KEYPAD OPERATION erare irtaantuneen naaa 4 3 4 6 QUICK S TFART PROCEDURES cesta aia 4 4 4 6 1 DC Integrator Measurement In Units of V s WDN or MN 4 4 4 6 2 DC Flux Measurement In Units of V sq Mx OF Wb 4 5 4 6 3 DC Flux Density Measurement In Units of Oort 4 6 4 6 4 Moment Measurement In Unit Of Wb CM ooccoconcccconnococinononacano nono ncnnnnnn corn nnnn cnn rra cnn 4 7 4 6 5 Potential Measurement In Unit Of A 4 8 5 ADVANCED OPERAT ON seet ested essiceecedtccsnceesiceshdiceddecessccdes sdtesaccdasheucgjacetssecssdecagscudsteccetecudy seccty 5 1 5 0 GENERAL cuirs tive A Sinai ier ad adh ia eel ey eee 5 1 5 1 UNITS SELECTION casi Acie A A EEN 5 1 5 2 EES 5 2 5 3 SE EIER aa geet cer ere ered err tcc creer eer ccna ae tree 5 2 5 3 1 INPUt RESISTANCE EE 5 3 5 3 2 Goll TEEN 5 4 5 3 3 Numberof Tunas Noia ee Ee EES 5 4 5 3 4 AO A A eege E te gee eee Eege 5 4 5 3 5 NC rE E A O EE AET 5 5 5 3 6 Helmholtz Constant 5 5 5 3 7 See EE 5 5 5 4 MAKING MEASUREMENTS IN PERCENT occiccccconccononcnonnncnoncnnonnnnnnnncnnnnc cnn cnn rca cnn 5 6 5 4 1 Before Using Set Percent nn 5 6 5 4 2 Set Percent UE ereeschen Eed edd Eder nese 5 6 5 4 3 Percent Scale Fcio td aa dedo 5 6 5 5 GOIECALIBRATION tii ida 5 7 5 5 1 Before using Coil Calbratton nr 5 7 5 5 2 let CC ee 5 7 5 6 COIL SEL
73. ON GENERAL This chapter provides general service and calibration information for the Lake Shore Model 480 Fluxmeter General maintenance precautions are described in Paragraph 8 1 electrostatic discharge in Paragraph 8 2 line voltage selection in Paragraph 8 3 fuse replacement in Paragraph 8 4 rear panel connector definitions in Paragraph 8 5 top of enclosure remove and replace procedure in Paragraph 8 6 EPROM replacement in Paragraph 8 7 error messages in Paragraph 8 8 and calibration in Paragraph 8 9 There are no field serviceable parts inside the Model 480 Contact Lake Shore about specific problems with the Model 480 GENERAL MAINTENANCE PRECAUTIONS Below are general safety precautions unrelated to any other procedure in this publication These are recommended precautions that personnel should understand and apply during the maintenance phase Keep away from live circuits Installation personnel shall observe all safety regulations at all times Turn off system power before making or breaking electrical connections Regard any exposed connector terminal board or circuit board as a possible shock hazard Discharge charged components only when such grounding results in no equipment damage If a test connection to energized equipment is required make the test equipment ground connection before probing the voltage or signal to be tested Do not install or service equipment alone Do not reach into or adjust the equipment without hav
74. Returned Remarks PEAKM Input Returned Remarks PKNEG Input Returned Remarks PKPOS Input Returned Remarks PKRST Input Returned Remarks PROBE Input Returned Remarks Example PROBE Input Returned Remarks Lake Shore Model 480 Fluxmeter User s Manual Query Peak Hold Function Off On PEAK 0 or 1 Format n term Queries the peak hold function 0 Normal reading 1 Peak hold Configure Peak Hold Mode PEAKM lt mode gt Nothing Configures the peak hold mode 0 Positive peak 1 Negative peak 2 Both positive and negative peaks Capturing both peaks decreases sampling frequency by a factor of 4 Query Peak Hold Mode PEAKM 0 1 or 2 Format n term Queries the peak hold mode 0 Positive peak 1 Negative peak 2 Both positive and negative peaks Capturing both peaks decreases sampling frequency by a factor of 4 Query Negative Peak Reading PKNEG nn nnnEznn Returns current negative peak reading in exponential form in the currently selected units Query Positive Peak Reading PKPOS inn nnnEznn Returns current positive peak reading in exponential form in the currently selected units Initiate Peak Reset Command PKRST Nothing Resets the peak hold circuit and the peak hold values Set Probe Serial Number and Date PROBE lt serial number gt lt date gt Nothing Sets the serial number and date for the attached probe A pr
75. T 062 5K Transverse Reference Magnet 0 062 inch gap 5 kG 0 5 MRT 062 10K Transverse Reference Magnet 0 062 inch gap 10 kG 5 MRT 343 50 Transverse Reference Magnet 0 343 inch gap 50 G 1 MRT 343 100 Transverse Reference Magnet 0 343 inch gap 100 G 1 Half Rack Mounting Kit for One Model 480 Fluxmeter Half length mounting panel and mounting ears to attach one Model 480 Fluxmeter to a 483 mm 19 inch rack mount space See Figure 7 7 Dual Mounting Shelf for Two Model 480 Fluxmeters Mounting panel and mounting ears to attach two Model 480 Fluxmeters to a 483 mm 19 inch rack mount space See Figure 7 8 7 2 Accessories Coils and Probes Lake Shore Model 480 Fluxmeter User s Manual 7 2 FIELD MEASURING PROBES Lake Shore offers two standard field measuring probes Check Lake Shore brochures or our website for recent additions to this line Probes are accurately calibrated using field standards maintained at Lake Shore Most standards are traceable to physical standards such as carefully controlled dimensions or sometimes proton resonance Probes are calibrated for use in flux or flux density units Pertinent calibration information including number of turns effective area and resistance are stored in a PROM located in the probe connector Users need only attach the probe to the fluxmeter turn on the instrument set the range and re set the zero before taking readings No manual input of coil parameters is necessary
76. Weighting Event Name 0 1 OPC 4 16 EXE 2 4 QYE 5 32 CME 3 8 DDE 7 128 PON Computer Interface Operation Lake Shore Model 480 Fluxmeter User s Manual IDN Query Identification Input IDN Returned lt manufacturer gt lt model numbers lt serial number gt lt firmware date gt Format LSCI MODEL480 aaaaaa nnnnnnfiterm Remarks Identifies the instrument model and software level OPC Operation Complete Command Input OPC Returned Nothing Remarks Generates an Operation Complete event in the Event Status Register upon completion of all pending selected device operations Send it as the last command in a command string OPC Query Operation Complete Input OPC Returned 1 Format n term Remarks Places a 1 in the controller output queue upon completion of all pending selected device operations Send as the last command in a command string This is not the same function as the OPC command RST Reset Instrument Input RST Returned Nothing Remarks Sets controller parameters to power up settings SRE Configure Status Reports in the Service Request Enable Register Input SRE lt bit weighting gt Returned Nothing Remarks Each bit has a bit weighting and represents the enable disable status of the corresponding status flag bit in the Status Byte Register To enable a status flag bit send the command SRE with the sum of the bit weighting for each desired bit Refer to the STB command f
77. a fully digital circuit Fluxmeter Measurements In Magnetizers Magnet materials such as Alnico and Samarium Cobalt are not permanent magnets until they are conditioned in a magnetizer The magnetizer produces strong fields by passing current through a coil fixture The magnetizer and coil fixture are optimized based on the magnet material and shape If the magnetizing field is not strong enough the magnet will not be fully magnetized Best cycle times and coil life are achieved when the magnetizer is operated at the minimum voltage required to attain the needed magnetic field The Model 480 provides an easy way to measure the peak field when the magnetizer voltage is being determined during initial setup Peak field is best measured in an empty magnetizer fixture During production magnetizing fixtures age and it is not uncommon for a coil turn to short Magnetizer current measurements are not enough to identify many fixture problems Peak field should be measured periodically as part of a quality control process and to determine the general health of the fixture Many users want a way to determine if the Model 480 is fast enough to capture the peak field generated by their magnetizer The remainder of this section describes how the Model 480 can be used with even the fastest magnetizers if the sense coil is designed properly Discussion begins with an approximation of the wave shape of the field generated by a magnetizer The maximum rate of change i
78. al magnet material charged to saturation and stabilized down to a particular value The same temperature coefficients hold true as in the transverse probe and the same care in handling must be observed This assembly uses concentric mu metal shield cans to protect the magnet from the effects of external magnetic field Axial reference magnets are available in values up to 1 kG with 500 G being the most widely used value When a probe is inserted completely through the access guide three distinct magnetic peaks will be observed on the gaussmeter One peak occurs as the probe enters the magnet a second and greater peak is observed as the midpoint is reached and a third smaller peak is read as the probe leaves the magnet The calibration point is the largest reading in the midpoint area Its amplitude will be approximately twice that of the readings that occur where the probe enters or leaves the magnet 4 7 cm dia L 1 845 gt 4 cm 1 56 2 9 cm 1 13 0 32 d a min gap Transverse 0 062 gap MRT 062 200 within 1 of nominal value MRT 062 500 within 1 af nominal value MRT 062 1K within 0 5 of nominal value MRT 062 2K within 0 5 of nominal value MRT 062 5K within 0 5 of nominal value Center line of magnet is center of gap Transverse 0 062 gap MRT 062 10K within 0 5 of nominal value working space Axial 0 312 diameter working space MRA 312 2K within 1 of nominal value MRA 312 1K within 1
79. alues can be displayed The instrument defaults to displaying of both peaks If both peaks are displayed the instrument update rate and peak reset time are slowed The instrument can read both peak values in about one fourth the normal update rate Peak reset time is doubled To select positive or negative peak press and hold the Peak Hold key for 5 seconds The following screen is displayed Se ect Wi h 47F Peak Mode Bot h Use the A or Y keys to select Positive Negative or Both peaks When the cursor indicates the desired peak press the Enter key to accept it or the Escape key to exit the screen and revert to the previous peak FILTER The display filter function quiets the display making it more readable when the probe is exposed to a noisy field Take care when using the filter on changing fields it may slow instrument response Users may configure the filter function to view desired field changes and block noise The filter is not used in Peak Hold To turn on the display filter press the Filter key to display the following screen Sel ect With 47 Fil ter On sOf f Press the Filter key or the s or t keys to toggle between On and Off Press the Enter key to accept the new setting or the Escape key to retain the old setting and return to the normal display Advanced Operation Lake Shore Model 480 Fluxmeter User s Manual Filter Continued 5 13 5 14 When the Filter is turne
80. an international listing noise electrical Unwanted electrical signals that produce undesirable effects in circuits of control systems in which they occur normalized sensitivity For resistors signal sensitivity dR dT is geometry dependent i e dR dT scales directly with R consequently often this sensitivity is normalized by dividing by the measured resistance to give a sensitivity sr in percent change per kelvin st 100 R dR dT K where T is the temperature in kelvin and R is the resistance in ohms normally closed N C A term used for switches and relay contacts Provides a closed circuit when actuator is in the free unenergized position normally open N O A term used for switches and relay contacts Provides an open circuit when actuator is in the free unenergized position oersted Oe The cgs unit for the magnetic field strength H 1 oersted 1034r ampere meter 79 58 ampere meter ohm Q The SI unit of resistance and of impedance The ohm is the resistance of a conductor such that a constant current of one ampere in it produces a voltage of one volt between its ends pascal Pa The SI unit of pressure equal to 1 N m Equal to 1 45 x 10 psi 1 0197 x 10 5 kgf cm 7 5 x 107 torr 4 191 x 107 inches of water or 1 x 10 5 bar A 4 Glossary of Terminology Lake Shore Model 480 Fluxmeter User s Manual permeability Material parameter which is the ratio of the magnetic induction B to the magnet
81. an be configured as an iron free solenoid in which the field is produced along the axis of the coil or an iron cored structure in which the field is produced in an air gap between pole faces The coil can be water cooled copper or aluminum or superconductive electron An elementary particle containing the smallest negative electric charge Note The mass of the electron is approximately equal to 1 1837 of the mass of the hydrogen atom electrostatic discharge ESD A transfer of electrostatic charge between bodies at different electrostatic potentials caused by direct contact or induced by an electrostatic field error Any discrepancy between a computed observed or measured quantity and the true specified or theoretically correct value or condition Fahrenheit F Scale A temperature scale that registers the freezing point of water as 32 F and the boiling point as 212 F under normal atmospheric pressure See Temperature for conversions flux The electric or magnetic lines of force in a region gamma A cgs unit of low level flux density where 100 000 gamma equals one oersted or 1 gamma equals 10 oersted gauss G The cgs unit for magnetic flux density B 1 gauss 10 tesla 1 Mx cm line cm Named for Karl Fredrich Gauss 1777 1855 a German mathematician astronomer and physicist gaussian system units A system in which centimeter gram second units are used for electric and magnetic qualities A 2 Glossar
82. an instrument or sensor to maintain a constant output given a constant input susceptance In electrical terms susceptance is defined as the reciprocal of reactance and the imaginary part of the complex representation of admittance Suscept ibility conduct ance Glossary of Terminology A 5 Lake Shore Model 480 Fluxmeter User s Manual susceptibility x Parameter giving an indication of the response of a material to an applied magnetic field The susceptibility is the ratio of the magnetization M to the applied field H y M H In both SI units and cgs units the volume susceptibility is a dimensionless parameter Multiply the cgs susceptibility by 47 to yield the SI susceptibility See also Initial Susceptibility and Differential Susceptibility As in the case of magnetization the susceptibility is often seen expressed as a mass susceptibility or a molar susceptibility depending upon how M is expressed temperature scales See Kelvin Scale Celsius Scale and ITS 90 Proper metric usage requires that only kelvin and degrees Celsius be used However since degrees Fahrenheit is in such common use all three scales are delineated as follows Boiling point of wate 373 15 K 100 C 212 F Triple point of wate 273 16 K Freezing point of water 273 15 K 0 C 32 F Absolute zero OK 273 15 C 459 67 F kelvin Celsius Fahrenheit To convert kelvin to Celsius subtract 273 15 To convert Celsius to Fahrenheit multiply C by 1 8 then a
83. appears on the display when the feature is on The annunciator blinks and the audible alarm sounds when an alarm is active All alarm functions are non latching and do not require a reset 5 15 ANALOG OUT OPERATION The Model 480 has two analog voltage outputs Corrected and Monitor The two outputs are quite different and not always suitable for the same applications 5 15 1 Corrected Analog Output The Model 480 digitally generates the corrected analog output voltage with a DAC This output is not real time It is updated 30 times a second during normal operation In dual peak both mode the Corrected Analog Output alternates between the positive and negative peak values 7 times a second For a steady state output either the positive or negative peak mode must be selected Instrument and coil calibrations can be taken into account making the corrected output more accurate than the monitor output The corrected output voltage is scaled to the DC reading value in DC mode the peak value in DC Peak or AC Peak modes and the RMS value in AC mode The corrected output is a variable DC voltage source that can vary from 10 V to 10 V Voltage is generated by a 16 bit DAC with a resolution of 0 3 mV or 0 003 of 10 V The output is short protected but should never be used to drive a resistance of less than 1 kQ for specified accuracy Analog output terminals are in the detachable terminal block on the rear of the instrument The corrected output ha
84. area turns entry or press the Coil Setup key and press the Enter key until the Helmholtz Constant screen appears Hel mhol t z Const ant RB DANZ cm Use the numeric keypad to enter the Helmholtz constant in cm then press the Enter key The cursor will jump to a space before the cm Use the a or v keys to select prefix u m _ k or M Press the Enter key then the Escape key Potential Constant A potential constant of a potential coil is required for the Model 480 to make magnetic potential measurements The only available potential measurement unit is A The potential constant must be entered in the empirically derived units of A V s To enter Potential constant continue from Helmholtz constant entry or press the Coil Setup key and press the Enter key until the Potential Constant screen appears Potenti al Const ant 1 DDR HS Use the numeric keypad to enter the Potential constant in A V s then press the Enter key The cursor will jump to a space before the A Vs Use the a or v keys to select prefix u m _ k or M Press the Enter key then the Escape key Advanced Operation 5 5 5 4 5 4 1 5 4 2 5 4 3 Lake Shore Model 480 Fluxmeter User s Manual MAKING MEASUREMENTS IN PERCENT For applications where an absolute measurement in magnetic units is not required the Model 480 offers the units of percent This is intended to be a relative measurement for sorting operations or c
85. ator is 1 SC Vous Vat The product Rin Cint is called the integrator time constant but for practical purposes 1 RinCint can be considered the integrator gain A more complete expression for flux is oc mE JW dt In the ideal case Rin and Cint could be any value and only their product would matter In reality there are practical limits to both Instrument manufacturers optimize the two values for best performance Many specifications are given based on specific values of Rin and Cint CG INT Ideal Operational Amplifier Integrator Circuit C 480 2 3 eps For most users the choice of fluxmeter Rin and Cint has little meaning to their measurement There are exceptions The integrator resistance is the sum of input resistance and coil resistance Coil resistance must be accounted for when it is a meaningful percentage of Rin Refer to Paragraph 2 2 3 for more details 2 2 Magnetic Measurement Overview Lake Shore Model 480 Fluxmeter User s Manual Important Integrator Characteristics Continued 2 1 5 Other integrator characteristics that may affect measurements are drift maximum input voltage and maximum and minimum rate of input change These characteristics are a result of fluxmeter design the user often has little control Check specifications carefully before choosing a fluxmeter for any application or designing a coil for a fluxmeter Reducing Integrator Drift Drift is the most noticeable and o
86. between two points on a permanent magnet The potential coil is generally a long thin solenoid The tip of the coil is placed perpendicular to the pole of a magnet with the other end of the coil out near zero field The difference between readings at the two poles is the magnetic potential difference Important Parameters of a Potential Coil It is important that the potential coil length is much larger than its diameter Coil area and number of turns determine sensitivity The coil must be much longer than the volume of magnetic field An empirically derived calibration constant Kp in amps per volt seconds A V s is often provided with the coil to allow a fluxmeter to operate in the SI unit of amps Magnetic Measurement Overview 2 13 Lake Shore Model 480 Fluxmeter User s Manual This Page Intentionally Left Blank 2 14 Magnetic Measurement Overview 3 0 3 1 3 1 1 3 1 2 Lake Shore Model 480 Fluxmeter User s Manual CHAPTER 3 INSTRUMENT SETUP GENERAL This chapter provides setup information for the Lake Shore Model 480 Fluxmeter A general layout for the Model 480 rear panel and information on how to make line power coil probe and terminal block connections to the Model 480 are provided If you want to experiment with the various software settings covered in the next chapter before doing a complete hardware setup the Model 480 may be operated with only the line power connected i e no coil probe or terminal blo
87. bilities SH1 AH1 T5 L4 SR1 RL1 PP0 DC1 DT0 CO E1 Serial Interface RS 232C Electrical DA 9 Connector 9600 BAUD External Reset Type Contact Closure Alarms Number 2 Settings High and low set point Inside Outside Audible Actuators Display Annunciator Beeper Relays for High Low and Middle Relays Number of Relays 3 Contacts Normally open NO normally closed NC and common C Contact Rating 30 VDC at2A Operation Follows high and low alarms Can be operated manually Connector Detachable terminal block Monitor Analog Output Scale 3V FS on Vs range Accuracy 1 of reading 10 mV DC to 10 kHz 5 of reading 10 mV 10 kHz to 50 kHz Minimum load resistance 1 KQ Connector Detachable terminal block Corrected Analog Output Scale User Selected Range 10 V Resolution 0 3 mV Accuracy 2 5 mV Minimum load resistance 1 KQ Connector Detachable terminal block General Ambient Temperature 15 35 C at rated accuracy 5 40 C with reduced accuracy Power Requirement 100 120 220 240 VAC 5 10 50 or 60 Hz 20 watts Size 217 mm W x 90 mm H x 317 mm D half rack 8 5 x 3 5 x 12 5 inches Weight 3 kilograms 6 6 pounds Approval CE Mark consult Lake Shore for availability Ordering Information Part number Description Instrument 480 Fluxmeter Specify line voltage when ordering Instrument Accessories RM 1 2 Rack Mount Kit for mounting one Ye rack fluxmeter in 482 6 mm rack RM 2 Rack Mount Kit for mounti
88. c parts are more ESDS than others ESD levels of only a few hundred volts may damage electronic components such as semiconductors thick and thin film resistors and piezoelectric crystals during testing handling repair or assembly Discharge voltages below 4000 volts cannot be seen felt or heard Service and Calibration 8 1 8 2 1 8 2 2 8 3 Lake Shore Model 480 Fluxmeter User s Manual Identification of Electrostatic Discharge Sensitive Components Below are various industry symbols used to label components as ESDS o e EZ Handling Electrostatic Discharge Sensitive Components Observe all precautions necessary to prevent damage to ESDS components before attempting installation Bring the device and everything that contacts it to ground potential by providing a conductive surface and discharge paths As a minimum observe these precautions 1 De energize or disconnect all power and signal sources and loads used with unit 2 Place unit on a grounded conductive work surface 3 Ground technician through a conductive wrist strap or other device using 1 MQ series resistor to protect operator 4 Ground any tools such as soldering equipment that will contact unit Contact with operator s hands provides a sufficient ground for tools that are otherwise electrically isolated 5 Place ESDS devices and assemblies removed from a unit on a conductive work surface or ina conductive container An operator inserting or remo
89. cccns 5 16 5 14 1 Alarm Re EE 5 17 5 14 2 Relay EI EE 5 18 5 14 3 Turning Alarm On and On 5 19 5 15 ANALOG OUT OPERATION th aie tira aii Aidt th ieee dd 5 19 5 15 1 Corrected Analog QUtPUt fesen etnea a a arara Aaa AA raaa AAE N TAa EAE TANER 5 19 5 15 2 Monitor Analog EU ee eege tan eae Alaa ae a dh 5 20 5 16 EXTERNAL RESET ugeet cue tai aki eta ans aut te 5 21 5 17 OPTIONAL INPUT eege ih steel ee ha EEN Ce 5 21 5 18 LOCKING AND UNLOCKING THE KEYPAD coocccocccococcnonoccconcnnonncnononcnanccnnnnnnnnnnnnnn cnn 5 21 5 19 RESETTING TO DEFAULT VALUES ninian uinna a cn narran nn ia 5 22 6 COMPUTER INTERFACE OPERATION ccoccccicnncnccnnncccnnnnnnnnna renacer 6 1 6 0 GENERAL aii 6 1 6 1 EEE 488 INTERFACE eeneg ueeeggieek s rie gereeegbe ebe gert Sege eege chashethadscabauieshathbasleansass 6 1 6 1 1 IEEE 488 Interface Settings ccccccececeeenceeeeeeeceeeeeeaaeseeneeceaeeeeeaeeeeaaeseeeeseaeeesaeeseaeeeeaes 6 2 6 1 2 IEEE 488 Command Structure cooocccccccconocanonococoncnnnnncno no nn nan c conca n arrancan cnn 6 2 6 1 3 Status RegistelS isuna a ita 6 3 6 1 4 IEEE Interface Example PrograMS ooooocccccnnoccccnononcnnnanonnnncnnoncnn nano nn nn nnnn cnn rra rn rnnnn rra 6 5 6 1 5 Troubleshooter a abba iii 6 13 6 2 SERIAL VO INTERFAGE uti a id 6 14 6 2 1 Serial Interface Hardware Configuration cooonncinnnnninnccnnnccnnocnnnccnnancccnnrnn rana 6 14 6 2 2 Serial Interface Geittngs nr 6 14 6 2 3 Serial Interface Example Programs oonoccoicccn
90. ce a line fuse There are two basic power configurations U S and International Units produced for use in the U S have a single fuse on the hot Units produced for International use have a double fuse for the hot and neutral To change line input from the factory setting use the appropriate fuse in the connector kit shipped with the instrument Test fuse with ohmmeter Do not rely on visual inspection of fuse WARNING To avoid potentially lethal shocks turn off controller and disconnect it from AC power before performing these procedures CAUTION For continued protection against fire hazard replace only with the same fuse type and rating specified for the line for the line voltage selected Locate line input assembly on the instrument rear panel See Figure 8 1 Turn power switch Off O Remove instrument power cord With a small screwdriver release the drawer holding the line voltage selector and fuse OW os GOs Nr are Remove existing fuse s Replace with proper Slow Blow fuse ratings as follows 100 120 V 0 25 A T 250 V 0 25 x 1 25 inches 220 240 V 0 200AT250V 5x 20mm Re assemble line input assembly in reverse order Verify voltage indicator in the line input assembly window Connect instrument power cord Oo OND Turn power switch On I Service and Calibration 8 3 Lake Shore Model 480 Fluxmeter User s Manual 8 5 REAR PANEL CONNECTOR DEFINITIONS The connectors on the rear panel of the Model 4
91. ck connections CAUTION Before plugging in the Model 480 and turning it on read about line voltage settings in Paragraph 3 3 An improper line voltage setting may damage the Model 480 Check it carefully before powering the instrument for the first time This chapter covers receiving the Model 480 in Paragraph 3 1 rear panel control definitions in Paragraph 3 2 power line input assembly in Paragraph 3 3 coil input connections in Paragraph 3 4 probe input connection in Paragraph 3 5 and terminal block in Paragraph 3 6 RECEIVING THE MODEL 480 This section covers inspection and unpacking in Paragraph 3 1 1 and repackaging for shipment in Paragraph 3 1 2 Inspection and Unpacking Inspect shipping containers for external damage Make all claims for damage apparent or concealed or partial loss of shipment in writing to Lake Shore within five 5 days from receipt of goods If damage or loss is apparent please notify the shipping agent immediately Use the packing list included with the instrument to verify receipt of the instrument probe and or coil accessories and manual Inspect for damage Inventory all components supplied before discarding any shipping materials If there is freight damage to the instrument file proper claims promptly with the carrier and insurance company and notify Lake Shore Notify Lake Shore immediately of any missing parts Lake Shore cannot be responsible for any missing parts unless notified within 60 days
92. cnonononononnnnnnnnnnns 8 4 8 5 1 Serial Interface Cable WiritQ ccccccceceeesceeeeeeeceeeeeeaaeeeeeeeseaeeeeaaeeeeaaeseeeeeseaeeesaeeseneeenees 8 6 8 5 2 IEEE 488 Interface Connector virsai oiie i a A t a i aaa 8 7 8 6 TOP OF ENCLOSURE REMOVAL AND REPLACEMENT cooccccccnnnccnncnncnncnonannnnnnnnnnncnonannnos 8 8 8 6 1 Removal Procedure 7 20191 ege ee ees 8 8 8 6 2 Installation Proc dure EE 8 8 8 7 EPROM REPLAGEMENT a de ee ee eet EE 8 8 8 8 ERROR MESSAGES o bon e ea o 8 9 8 9 CALIBRATION PROCEDURE ccocccccccnncncconocononoconcnnnonononcnnnnnncononnonnnnnnnnnonononnnnnnnnnnannnnnnonnnos 8 10 8 9 1 Required Equipment LIST oori oirean rE Sern EDE AANE OENE rn 8 10 8 9 2 AID Reference Voltages cui caia AR 8 10 8 9 3 Initialize for Calibration nnnneanoennnnnnnnansennnnnnasensennnnnnnssnnrninnnnnssrnnnnrnnsansnnnnnnnnsnnsrnnnnnnn 8 10 8 9 4 AG Peak Onset eege o a A getest 8 11 8 9 5 AC RMS and AC Peak Gain Calibration ocooccccccnnoncnanonooocnnonononanononncnnnnnnnnnnconnnnnnns 8 11 8 9 6 DC and DC Peak CGalbration 8 12 8 9 7 luese te EE 8 13 8 9 8 Finalize CGalbraton t neri aade rn tavade ana aieeaa daa tara i dat aer kaa aena i taenia tatt 8 14 APPENDIX A GLOSSARY OF TERMINOLOGY c cccccsssesseeeceseeesnsenssceeseseensnnsneacoeseseeasnnsssacoesesees A 1 APPENDIX B UNITS FOR MAGNETIC PROPERTIEG s sccecceesnssnssceeeeeeeesnsenssceeseseensnnssaneeseeees B 1 iv Table of Conte
93. d ground referenced Input Resistance 100 kQ or 10 kQ Maximum Operating Input Voltage 60 V Absolute Maximum Input Voltage 100 V WARNING Voltages between 60 V and 100 V will not damage the instrument but could result in damage to other instruments or personal injury Update Rate 5 readings per second on display 30 readings per second IEEE 488 30 readings per second serial DC DC Display Resolution To 5 digits DC Integrator Capacitance 1 uF nominal DC Input Resistance 100 KQ 10 kQ DC Ranges 300 mVs 30 mVs 30 mVs 3 mVs DC Resolution 0 001 mVs 0 0005 mVs 0 0005 mVs 0 0005 mVs DC Accuracy Offset 10 uVs DC Integrator Drift Gain 0 25 of reading lt 10 Vs s max rate of change DC Minimum d dt 20 uVs minute DC Maximum do dt 60 Vs s DC Integrator Drift 1 uVs minute 0 0004 FS minute on 300 mVs range 100 kQ input resistance constant temperature environment DC Peak DC Peak Display Resolution 4 digits DC Peak Integrator Capacitance 1 uF nominal DC Peak Input Resistance 100 kQ 10 KQ DC Peak Ranges 300 mVs 30 mVs 30 mVs 3 mVs DC Peak Resolution 0 01 mVs 0 001 mVs 0 001 mVs 0 001 mVs DC Peak Min Reading 0 05 mVs 0 005 mVs 0 005 mVs 0 005 mVs DC Peak Accuracy Offset 100 uVs DC Integrator Drift Gain 5 of reading lt 10 Vs s max rate of change DC Peak Maximum d dt 60 Vs s DC Peak Update Rate May reduce update rate to 1 4 normal AC AC D
94. d on two additional displays appear The first is Filter Points The Filter Points display sets the number of points to use in the filter algorithm Se ect Wi th atF Fil ter Poi nts b Use the s or t keys to increment or decrement the Filter Points number from 2 to 64 points 8 is the default The unit takes one point each update cycle so filter settling time depends on update speed and number of points Press the Enter key to accept the new setting or the Escape key to retain the old setting and return to the normal display The Model 480 uses an exponential algorithm to smooth response The settling time to full display resolution is about the same as the number of filter points in seconds For example a setting of 10 filter points settles in about 10 seconds The second display is Filter Window The Filter Window display sets a limit for restarting the filter Sel ect With 47 Filteri ndow 1 gz Press the Filter key or the s or t keys to increment or decrement the Filter Window percentage from 1 to 10 1 is the default Press the Enter key to accept the new setting or the Escape key to retain the old setting and return to the normal display If a single field reading differs from the filter value by more than the limit specified the instrument assumes an intentional change and restarts the filter at the new reading value This allows faster instrument response to changing fields than if the filter f
95. dd 32 or F 1 8 x C 32 To convert Fahrenheit to Celsius subtract 32 from F then divide by 1 8 or C F 32 1 8 temperature coefficient measurement The measurement accuracy of an instrument is affected by changes in ambient temperature The error is specified as an amount of change usually in percent for every one degree change in ambient temperature tesla T The SI unit for magnetic flux density B 1 tesla 104 gauss thermal emf An electromotive force arising from a difference in temperature at two points along a circuit as in the Seebeck effect tolerance The range between allowable maximum and minimum values turns N One complete loop of wire In the Model 480 the turns of a coil must be entered to perform flux measurements in units of Volt seconds Vso Webers Wb9 or Maxwells Mx9 Underwriters Laboratories UL An independent laboratory that establishes standards for commercial and industrial products unit magnetic pole A pole with a strength such that when it is placed 1 cm away from a like pole the force between the two is 1 dyne vector A quantity that has both magnitude and direction and whose components transform from one coordinate system to another in the same manner as the components of a displacement Also known as a polar vector volt V The difference of electric potential between two points of a conductor carrying a constant current of one ampere when the power dissipated bet
96. de with no changing field present at the coil Automatic Drift Adjustment The Model 480 can adjust drift by measuring the change in reading over a fixed time interval and calculating the appropriate coarse drift compensation DAC value The sequence takes approximately 25 seconds A well calculated coarse DAC value will give acceptable drift performance for most applications The fine drift compensation DAC is set to 0 during the operation The fine DAC can be set manually or by the DriftTrak algorithm for improved drift performance An error message will appear on the instrument display if automatic drift adjustment failed If the message appears check all coil connections allow the instrument more time to warm up and try again After the coil is connected and the instrument has warmed up initiate automatic drift adjustment by pressing the Drift Adjust key The message Begin Auto Adjust will appear Press the Enter key to start or the Escape key to return to the main display If you pressed the Enter key you will see the following display ADIUSTI HG BDRI FT For 25 Seconds The message will remain visible for 25 seconds then return to the normal display Pressing the Escape key during this time will cancel the sequence and return to normal operation 5 10 Advanced Operation 5 9 2 5 9 3 Lake Shore Model 480 Fluxmeter User s Manual Manual Drift Adjustment For manual drift adjustment the two
97. drift compensation DACs in the Model 480 can be thought of as precise trim potentiometer adjustments Each has a range of 0 to 100 and an effective resolution of 0 025 The coarse DAC should be set before the fine DAC if the coil has been changed or the instrument has been turned off During normal operation only fine DAC adjustments should be required After the coil is connected and the instrument has warmed up initiate manual drift adjustment by pressing the Drift Adjust key Use the A or Y keys until the Begin Manual Adjust message appears Press the Enter key and the course DAC setting screen will appear 4 661 4 _ 56 DC A 301 Coarse Use the A or Y keys until the display reading stops changing in one direction Press the Enter key again and the fine DAC setting screen will appear 4 661 A _ 6 DC 79 b4 Fi ne Use the A or Y keys until the drift in the display reading is acceptable Press the Enter key to complete the operation Press the Escape key during either adjustment to cancel the adjustment and return to normal operation DriftTrak DriftTrak is a proprietary drift control algorithm exclusive to Lake Shore Fluxmeters It is different than automatic and manual drift adjustment because it operates continuously keeping drift low over time DriftTrak works best after automatic drift adjustment has reduced drift to a low starting point The algorithm works only in DC mode For DC Peak
98. e Do DoEvents Loop Until gSend True gSend False strCommand frmSerial txtCommand Text strReturn strCommand UCase strCommand If strCommand EXIT Then End End If frmSerial MSComm1 Output strCommand amp Term If InStr strCommand lt gt 0 Then While ZeroCount lt 20 And strHold lt gt Chr 10 If frmSerial MSComml InBufferCount frmSerial Timerl Enabled True Do DoEvents Main code section Used to return response Temporary character space Terminators Counter used for Timing out Data string sent to instrument Show main window Terminators are lt CR gt lt LF gt Initialize counter Clear return string Clear holding string Close serial port to change settings Example of Comm 1 Example of 9600 Baud Parity Data Stop Read one character at a time Open port Wait loop Give up processor to other events Loop until Send button pressed Set Flag as false Get Command Clear response display Set all characters to upper case Get out on EXIT Send command to instrument Check to see if query Wait for response Add 1 to timeout if no character Wait for 10 millisecond timer Loop Until frmSerial Timerl Enabled False ZeroCount ZeroCount 1 Else ZeroCount 0 strHold frmSerial MSComml Input strReturn strReturn strHold End If Wend If strReturn lt gt Then strReturn Mid strReturn 1 InStr strReturn Else
99. e Escape key NOTE All the other settings Turns Area Turns etc are ignored when using moment units 8 Press the AC DC key until DC is displayed on the screen 9 Press the Peak Hold key until Peak Hold off is displayed on the screen 10 Press the Range key Use the a or v keys to select the range appropriate to your measurement 11 Press the Reading Reset key 12 If the instrument has just been turned on allow it to warm up for at least 10 minutes before proceeding Otherwise proceed to Step 13 13 Press the Drift Adjust key Use the a or y keys until Begin Auto Adjust is displayed Press the Enter key You will see the following message ADJUSTING DRIFT For 25 Seconds 14 Make the test measurement 15 If the reading appears to be drifting refer to the Drift Adjust discussion in Paragraph 5 9 Basic Operation 4 7 Lake Shore Model 480 Fluxmeter User s Manual 4 6 5 Potential Measurement In Unit of A Use the following procedure to take a potential measurement 1 Ensure power is turned Off O CAUTION Always turn off power to the Fluxmeter before making any rear panel PROBE INPUT or COIL INPUT connections 2 Attach the probe or coil to rear of the Fluxmeter Refer to Paragraph 3 4 for COIL INPUT and Paragraph 3 5 for PROBE INPUT connection instructions Turn power On I Press the Units key Potential measurements are done in the unit of Amperes A Press the 4 or v keys until P
100. e Model 480 Fluxmeter User s Manual Query AC Range Parameter RNGAC An integer from 0 to 3 Format n term Returns the Model 480 AC range 0 30 mV s 1 3 mV s 2 300 uV s 3 30 V s Configure DC Range Parameter RNGDC lt range gt Nothing Configures the Model 480 DC range 0 300 mV s 1 30 mV s Query DC Range Parameter RNGDC 0 or 1 Format n term Returns the Model 480 DC range 0 300 mV s 1 30 mV s Query Maximum Range Value RNGMX nnn nnnE tnn Returns the maximum range in the currently selected units This is the maximum reading the unit can handle on the current range setting Set Terminating Character TERM lt terminator gt Nothing Sets the IEEE 488 terminating character type lt terminator gt specifies the terminator 0 CR LF 1 LF CR 2 LF 3 No terminators Terminating characters are sent when the Model 480 completes its message transfer on output They also identify the end of an input message This command works only with the IEEE 488 Interface and does not change the serial terminators Query Terminating Character TERM 0 1 2 or 3 Format n term Returns the IEEE 488 terminating character type 0 CR LF 1 LF CR 2 LF 3 No terminators Configure Display Units Type UNITS lt unit number gt Nothing Configures the Model 480 to the units listed below 1 V s Flux turns 5 Wb Flux 2 MXN Flux turns 6 Mx Flux
101. e Set Percent Command Configure Peak Hold Function Off On 6 32 Query Peak Hold Function Off On 6 33 Configure Peak Hold Mode Query Peak Hold Mode Query Negative Peak Reading Query Positive Peak Reading Initiate Peak Reset Command Set Probe Serial Number and Date Query Probe Serial Number and Date 6 33 Initiate Reading Reset Command Query Present Display Reading Configure High Relay Function Query High Relay Function Configure Low Relay Function Query Low Relay Function Configure Middle Relay Function Query Middle Relay Function Configure AC Range Parameter Query AC Range Parameter Configure DC Range Parameter Query DC Range Parameter Query Maximum Range Value Configure Display Units Type Query Display Units Type 6 20 Computer Interface Operation 6 3 1 Syntax of what user must input 6 3 2 CLS Input Returned Remarks ESE Input Returned Remarks Example ESE Input Returned Remarks ESR Input Returned Remarks Explanation and definition Lake Shore Model 480 Fluxmeter User s Manual Command List Structure Command Name Brief Description of Function RNGDC Input Returned Query DC Range Parameter RNGDC 0 or 1 Format n term Returns the Model 480 DC Range O 300 mV s 1 30 mV s Information returned in Remarks response to the query of returned data IEEE 488 Serial Interface Commands Alphabetical Listing Clear Interface Command
102. e remaining magnetic induction in a magnetic material when the material is first saturated and then the applied field is reduced to zero The remanence would be the upper limit to values for the remanent induction Note that no strict convention exists for the use of remanent induction and remanence and in some contexts the two terms may be used interchangeably remanent induction The remaining magnetic induction in a magnetic material after an applied field is reduced to zero Also see remanence repeatability The closeness of agreement among repeated measurements of the same variable under the same conditions resolution The degree to which nearly equal values of a quantity can be discriminated display resolution The resolution of the physical display of an instrument This is not always the same as the measurement resolution of the instrument Decimal display resolution specified as n digits has 10 possible display values A resolution of n and one half digits has 2 x 10 possible values measurement resolution The ability of an instrument to resolve a measured quantity For digital instrumentation this is often defined by the analog to digital converter being used A n bit converter can resolve one part in 2 The smallest signal change that can be measured is the full scale input divided by 2 for any given range Resolution should not be confused with accuracy root mean square RMS The square root of the time average of the squa
103. e setting There are four decade range selections available for AC measurements and three for AC Peak measurements More ranges are allowed for AC because they do not suffer from the drift associated with DC measurements Drift on the high gain ranges make them unusable for DC measurement A smaller integrating capacitor is used for AC measurements allowing even more gain The difference in capacitance is why the largest full scale AC range is smaller than the largest full scale DC range AC ranges are specified with 100 kQ input resistance Coil construction can be changed to alter the range boundaries in magnetic units As an example of coil parameters altering range boundaries consider using the highest DC range of 300 mV s If a coil with an area turns of 100 cm is used on the highest DC range for flux density measurements the resulting range boundary in gauss would be 300 kG If a coil with an area turns of 1000 cm is used on the same range the resulting range boundary would be 30 kG If coil parameters are entered and units are selected before range is chosen the Model 480 will calculate and display the appropriate full scale range and resolution in the selected units Because of the construction of the Model 480 some over range should be expected Over range is typically 10 of the full scale shown but it is not guaranteed To changing the range press the Range key The following is a typical display Sel ect Wi th aF LA BEBES Use
104. ea When measuring flux density in a non uniform field the fluxmeter reads the average flux density There are some unique coil configurations that help eliminate the effect of field non uniformity The length to outer diameter ratio of a coil can be optimized to measure flux density at the center of the coil rather than the average flux density For more information consult Zijlstra H Experimental Methods in Magnetism Wiley pg 3 1967 Herzog amp Tischler Measurement of Inhomogeneous Magnetic Fields Review of Scientific Instruments Vol 24 pg 1000 1953 Lead Pickup Loops other than the sensor coil should be eliminated or minimized Loops in lead wires see changing flux just like a coil Their voltage is an error added or subtracted from the coil voltage Twisted leads from the coil to the fluxmeter are recommended to reduce loop area and minimize error voltage Inductance Capacitance and Self Resonance There are error sources that are only important when making AC or very fast peak DC measurements Keep coil inductance Leoi small or it acts similar to coil resistance and reduces sensitivity The real impedance of a coil due to inductance is 2x f Leo That value should be small compared to the input resistance of the integrator or the signal is attenuated The attenuation changes with frequency because the impedance does The equation for calculating inductance of an ideal long solenoid is U 3 1 where po
105. ed coil Lake Shore probes include all coil information necessary for operation Coil Setup Allows users to enter coil parameters for their own coils Press and hold to select 0 Q input resistance Lake Shore probes include all coil information necessary for operation Coil Select Selects 1 of up to 10 coil parameter sets previously stored by the user Each set may include a value of every coil parameter Press and hold to store user entered coil parameter sets 4 2 Basic Operation Lake Shore Model 480 Fluxmeter User s Manual KEYPAD DEFINITION Continued 4 5 Coil Cal Calibrates a users coil with a standard magnet or other known magnetic environment Set Percent Assigns a scale factor to enable readings in percent units Press and hold to view or manually set the percent scale factor Alarm Setup Configures alarm feature for the display and alarm relays Alarm On Off Turns alarm feature On or Off Local Returns instrument to local operation after the IEEE 488 interface has put it in remote mode Interface Selects the IEEE 488 address and terminators and serial interface baud rate Filter Configures the display filter which averages readings so environmental noise does not show up on the display Press and hold to select DC resolution Analog Out Selects corrected analog output operating mode There is no user control of monitor output Escape Terminates a setting function without changing the existing parameter value Pre
106. ed with the response ENTER COMMAND READ Reading Query Unit returns reading in the form XXX XX 001 000E 01 Decimal point placement appropriate to range ENTER COMMAND RNGDC DC Range Query Unit returns appropriate range 0 0 300 mV s or 1 30 mV s ENTER COMMAND UNITS Units Query Unit an integer from 1 to 11 corresponding to the T units being used In this example 1 V s ENTER COMMAND ACDC AC or DC Query Unit returns appropriate setting 0 0 DC 1 AC ENTER COMMAND FILT Filter Query Unit returns appropriate setting 0 0 Off 1 On ENTER COMMAND FILT 1 FILT Unit turns the filter On then returns a 1 to verify the change ik ENTER COMMAND Following are additional notes on using either Serial Interface program e If you enter a correctly spelled query without a nothing will be returned Incorrectly spelled commands and queries are ignored Commands and queries should have a space separating the command and associated parameters e Leading zeros and zeros following a decimal point are not needed in a command string but are sent in response to a query A leading is not required but a leading is required 6 2 4 Troubleshooting New Installation 1 Check instrument Baud rate 2 Make sure transmit TD signal line from the instrument is routed to receive RD on the computer and vice versa Use a null modem
107. ee coils are available as follows Refer to Paragraph 7 3 FH 2 5 Helmholtz Coil 2 5 inch inner diameter coil resistance 35 Q See Figure 7 3 FH 6 Helmholtz Coil 6 inch inner diameter coil resistance 110 Q See Figure 7 4 FH 12 Helmholtz Coil 12 inch inner diameter coil resistance 140 Q See Figure 7 5 FNT 6R04 100 Field Probe 100 cm Area turns Refer to Paragraph 7 2 1 and see Figure 7 1 FNT 5R04 30 Field Probe 30 cm Area turns Refer to Paragraph 7 2 2 and see Figure 7 2 MAN 480 MRA XXX MRT XXX Model 480 Fluxmeter User s Manual Reference Magnets High quality reference magnets are available in transverse flat and axial round configurations Refer to Paragraph 7 4 and see Figure 7 6 MRA 312 100 Axial Reference Magnet 0 312 inch inside diameter 100 G 1 MRA 312 200 Axial Reference Magnet 0 312 inch inside diameter 200 G 1 MRA 312 300 Axial Reference Magnet 0 312 inch inside diameter 300 G 1 MRA 312 500 Axial Reference Magnet 0 312 inch inside diameter 500 G 1 MRA 312 1K Axial Reference Magnet 0 312 inch inside diameter 1 kG 1 MRA 312 2K Axial Reference Magnet 0 312 inch inside diameter 2 kG 1 MRT 062 200 Transverse Reference Magnet 0 062 inch gap 200 G 1 MRT 062 500 Transverse Reference Magnet 0 062 inch gap 500 G 1 MRT 062 1K Transverse Reference Magnet 0 062 inch gap 1 kG 0 5 MRT 062 2K Transverse Reference Magnet 0 062 inch gap 2 kG 0 5 MR
108. eeeesaeeesaaeseeeeeseaeeeseaeeeeaeeeeaes 2 13 2 6 2 Important Parameters of a Potential Col 2 13 Be MOET UP eege 3 1 3 0 GENERAL ee ee teo oia dl ot See 3 1 3 1 RECEIVING THE MODEL 480 cooooonccccocccococononococoncnccnnnnononanann cnn ncn narran rra rra nn 3 1 3 1 1 Inspection and UNPACKING cccconoccccnnnoccccnanoccncnanoncnnnnnoncnn cano nn nn AEEA SEERE ER 3 1 3 1 2 Repackaging For Shipment ccccccceceeeeeeceeeeeceaeeeeeaeeeeeeeceeeeesaaeeesaaeseeeeeseaeesseaeeseaeeteaes 3 1 3 2 REAR PANEL DEFINITION miiia nn nn nan cc a e a eaaa e Eaa EA 3 2 3 3 LINE INPUT ASSEMBLY NV 3 2 3 3 1 Line Voltage and Fuse Verification ooooooccnnnnccnnonnccccnnnoncccnnnannccnnnoncccnnnnnccnnnna cnc nana nn 3 2 Table of Contents Lake Shore Model 480 Fluxmeter User s Manual TABLE OF CONTENTS Continued Chapter Paragraph Title Page 3 3 2 Nee Te WEE 3 2 3 3 3 POWER e EE 3 2 3 4 COIL INPUT CONNECTION kiiensis eaei A a 3 3 3 5 PROBE INPUT CONNECTION 3 2000 cee i eae ned ee 3 3 3 5 1 Attachment To A Non Lake Shore Col 3 3 3 6 TERMINAL BLOCK icv kite ia 3 4 3 6 1 Alarm Relay Connechon nana nn narran 3 4 3 6 2 Analog Output Connections oocccoccconocinonoccnonccnnoncnononnnnnn cnn rca rana narran crac 3 4 3 6 3 External Reset CONMNECtiONS ooooocnncccconccononcnononnnoncccnnrnnn nan nnn cnn rca rana nnn ra nan ranas 3 4 3 6 4 Optional Input Connechon nana crac 3 4 4 BASICOPERATION id 4 1 4 0 GENERAL eg dk Dees A DIA 4 1 4 1 TURNI
109. efer to Paragraph 6 2 3 1 for instructions on how to setup the program The Visual Basic code is provided in Table 6 6 The second program was written in Quick Basic Refer to Paragraph 6 2 3 2 for instructions on how to setup the program The Quick Basic code is provided in Table 6 7 Finally a description of operation common to both programs is provided in Paragraph 6 2 3 3 While the hardware and software required to produce and implement these programs not included with the instrument the concepts illustrated apply to almost any application where these tools are available 6 2 3 1 Visual Basic Serial Interface Program Setup The serial interface program works with Visual Basic 6 0 VB6 on an IBM PC or compatible with a Pentium class processor A Pentium 90 or higher is recommended running Windows 95 or better with a serial interface It uses the COM1 communications port at 9600 Baud Use the following procedure to develop the Serial Interface Program in Visual Basic Start VB6 Choose Standard EXE and select Open Resize form window to desired size On the Project Menu click Components to bring up a list of additional controls available in VB6 Scroll through the controls and select Microsoft Comm Control 6 0 Select OK In the toolbar at the left of the screen the Comm Control will have appeared as a telephone icon Select the Comm control and add it to the form Add controls to form a Add three Label controls to the form b
110. elect prefix u m _ K or M Press the Enter key to accept the change or the Escape key to cancel the entry and return the previous value The instrument will begin displaying in percent The sequence is successful if the display reading matches the value entered Percent Scale Factor The percent scale factor can be viewed or entered directly This feature allows the coil to be used again with the same scale factor or transferred from one instrument to another The scale factor is in the empirical units of V s To view or change the percent scale factor press and hold the Set Percent key for 5 seconds Percent Scal e Factor 7 6H DI Zelle Use the numeric keypad to enter the Percent Scale Factor in V s then press the Enter key The cursor will jump to a space before the Use the a or w keys to select prefix u m _ K or M Press the Enter key then the Escape key 5 6 Advanced Operation 5 5 5 5 1 5 5 2 5 6 Lake Shore Model 480 Fluxmeter User s Manual COIL CALIBRATION If coil parameters are not known and the user has access to reference magnet or other known field the Model 480 can be used to calculate the required coil parameter for magnetic measurement units Once a coil is calibrated the coil setup feature can be used to read the calibrated coil parameter Calibrated coil parameters can also be stored in instrument memory or a Model FCBL 6 accessory Coil calibration is
111. elmholtz coil to rear of the Fluxmeter Refer to Paragraph 3 4 for COIL INPUT and Paragraph 3 5 for PROBE INPUT connection instructions Turn power On I 4 Press the Units key Moment measurements are done in the unit of Webers per centimeter Wbcm Press the a or y keys until Moment Wbcm is displayed on the screen then press the Enter key A quick message that details which input parameters are necessary to perform calculations in the units you have selected will appear then disappear 5 Press the Coil Setup key For this procedure we will assume an Input Resistance of 100 kQ Press the a or v keys until Input R 100k is displayed on the screen press the Enter key then the Escape key 6 If the coil resistance is less than 100 or is unknown the default value of 0 Q is acceptable and you may skip this step Otherwise press the Coil Setup key Press the Enter key until Enter Coil R is displayed Use the numeric keypad to enter the coil resistance then press the Enter key The cursor will jump to a space before the Q symbol Use the a or v keys to select prefix for Q or k for KQ Press the Enter key then the Escape key 7 Press the Coil Setup key Press the Enter key until Helmholtz Constant is displayed Use the numeric keypad to enter the Helmholtz constant then press the Enter key The cursor will jump to a space before cm Use the a or v keys to select prefix _ Press the Enter key then th
112. en then press the Enter key A quick message that details which input parameters are necessary to perform calculations in the units you have selected will appear then disappear 5 Press the Coil Setup key For this procedure we will assume an Input Resistance of 100 kQ Press the a or v keys until Input R 100kQ is displayed on the screen press the Enter key then the Escape key 6 If the coil resistance is less than 100 or is unknown the default value of 0 Q is acceptable and you may skip this step Otherwise press the Coil Setup key Press the Enter key until Enter Coil R is displayed Use the numeric keypad to enter the coil resistance then press the Enter key The cursor will jump to a space before the Q symbol Use the a or v keys to select prefix for Q or k for KQ Press the Enter key then the Escape key NOTE All the other settings Turns Area Turns etc are ignored when using integrator units 7 Press the AC DC key until DC is displayed on the screen 8 Press the Peak Hold key until Peak Hold Off is displayed on the screen 9 Press the Range key Use the a or w keys to select the range appropriate to your measurement 10 Press the Reading Reset key 11 If the instrument has just been turned on allow it to warm up for at least 10 minutes before proceeding Otherwise proceed to Step 12 12 Press the Drift Adjust key Use the a or v keys until Begin Auto Adjust is displayed Press
113. er Table 8 1 7 Set Oscillator to the testing amplitude and frequency per Table 8 1 sine continuous 8 Calculate Ideal V s Voltmeter reading 2zf 9 Wait 30 seconds 10 Get Actual Model 480 reading 11 Calculate Calibration Constant 1e 7 x Ideal Actual NOTE This value must be 1e 7 11 A value outside this tolerance indicates a major malfunction of the Model 480 that requires repair Service and Calibration Lake Shore Model 480 Fluxmeter User s Manual AC RMS and AC Peak Gain Calibration Continued 12 Send Calibration Constant to the appropriate range location per Table 8 1 from the computer using the form CALGAIN lt location gt lt x xxxxxe x gt AC Peak Calibration 13 14 15 16 17 18 Set Model 480 to Dual Peak operation Calculate Ideal peak Ideal V s from Step 8 above x 1 4142 Wait 30 seconds Reset the Model 480 Get Actual peak readings Average 10 readings each taken 1 second after a reset Calculate Calibration Constant 1e 7 x Ideal peak Actual averaged NOTE This value must be 1e 7 11 A value outside this tolerance indicates a major malfunction 19 20 21 of the Model 480 that requires repair Send the Calibration Constant to the appropriate positive peak range location per Table 8 1 from the computer using the form CALGAIN lt location gt lt x xxxxxe x gt Send the same Calibration Constant to the appropriate negati
114. er User s Manual 6 0 6 1 CHAPTER 6 COMPUTER INTERFACE OPERATION GENERAL This chapter provides operational instructions for the computer interface for the Lake Shore Model 480 Fluxmeter Either of the two computer interfaces provided with the Model 480 permit remote operation The first is the IEEE 488 Interface described in Paragraph 6 1 The second is the Serial Interface described in Paragraph 6 2 The two interfaces share a common set of commands detailed in Paragraph 6 3 Use only one of the interfaces at a time IEEE 488 INTERFACE The IEEE 488 Interface is an instrumentation bus with hardware and programming standards that simplify instrument interfacing The Model 480 IEEE 488 Interface complies with the IEEE 488 2 1987 standard and incorporates its functional electrical and mechanical specifications unless otherwise specified in this manual All instruments on the interface bus perform one or more of the interface functions of TALKER LISTENER or BUS CONTROLLER A TALKER transmits data onto the bus to other devices A LISTENER receives data from other devices through the bus The BUS CONTROLLER designates to the devices on the bus which function to perform The Model 480 performs the functions of TALKER and LISTENER but cannot be a BUS CONTROLLER The BUS CONTROLLER is the digital computer which tells the Model 480 which functions to perform Below are Model 480 IEEE 488 interface capabilities e SH1 Source handshake capabi
115. er a wide frequency range using simple sensing coils Applications are limited to field volumes as large or larger than the coil but for some it is an inexpensive way to make low drift AC field measurements Drift Adjustment Adjusting or nulling the drift of an analog integrator wastes time It can be the only unpleasant part of using an integrating fluxmeter Lake Shore innovation brings some relief The Model 480 has a built in drift algorithm that continually adjusts drift when the instrument and coil are idle It is ready when you are to make precision low drift measurements The adjustment algorithm has no effect during flux integration Manual drift adjustment is also available Coils and Probes Coils and probes wound by the user or from other manufacturers can easily be used with the Model 480 The Model 480 allows the user to save parameters for up to 10 existing coils probes and quickly switch between them Lake Shore also offers several sensing coils and probe assemblies for use with the Model 480 which offer several conveniences They are factory calibrated for accuracy and interchangeability Calibration data is loaded into memory in the probe connector so it does not have to be entered by the user Special coil assemblies are also available and can be designed to meet customer specifications Introduction 1 1 Lake Shore Model 480 Fluxmeter User s Manual 1 2 SPECIFICATIONS Measurement Number of Inputs 1 Input Type Two lea
116. ersion of Coil Sensitivity The coil constant conversion factors can be derived by inverting and using the same math as above Coil Sensitivity in gauss per ampere 1 Sensitivity x 1 256 K cm Coil Sensitivity in milligauss per ampere 1 Sensitivity x 1256 K cm Coil Sensitivity in millitesla per ampere 1 Sensitivity x 0 1256 K cm Coil sensitivity in microtesla per ampere 1 Sensitivity x 125 6 K cm 2 12 Magnetic Measurement Overview Lake Shore Model 480 Fluxmeter User s Manual 2 6 MAGNETIC POTENTIAL OVERVIEW 2 6 1 2 6 2 What is Magnetic Potential Magnetic potential sometimes called magnetostatic potential is the line integral of magnetizing force between two points in a magnetic field It is the scalar value analogous to voltage in an electrical circuit The symbol for magnetic potential is U The CGS system measures magnetic potential in gilberts Gb or oersted times centimeters Oe cm The SI system measures it in amps A Magnetic potential can be used to derive the internal magnetic field strength H of a permanent magnet The difference in magnetic potential between two points where no electrical current exists is proportional to magnetic field strength H With magnetic field strength measured with a potential coil and flux density measured by other means the second quadrant operating point of the magnet can be determined A potential coil with a fluxmeter measures the magnetic potential difference
117. es Window 7 In the Properties window use the dropdown list to select between the different controls of the current project IEEE Interface Program AT E 10 Set the properties of the controls as defined in Table 6 1 11 Save the program Computer Interface Operation 6 7 Lake Shore Model 480 Fluxmeter User s Manual Table 6 1 IEEE 488 Interface Program Control Properties Current Name Property New Value Labeli Name IbIExitProgram Caption Type exit to end program Label Name lbICommand Caption Command Name lbIResponse haves Caption Response Texti Name txtCommand Text lt blank gt Name txtResponse Tente Text lt blank gt Name cmdSend Command1 Caption Send Default True Formit Name frmlEEE Caption IEEE Interface Program 12 Add code provided in Table 6 2 a Inthe Code Editor window under the Object dropdown list select General Add the statement Public gSend as Boolean b Double Click on cmdSend Add code segment under Private Sub cmdSend_Click as shown in Table 6 2 c Inthe Code Editor window under the Object dropdown list select Form Make sure the Procedure dropdown list is set at Load The Code window should have written the segment of code Private Sub Form_Load 1 Add the code to this subroutine as shown in Table 6 2 13 Save the program 14 Run the program The program should resemble the following ig IEEE Interface Program Al ES Type
118. es as viewed from the Model 480 rear panel IEEE 488 INTERFACE SH1 AH1 T5 L4 SR1 RL1 PPO DC1 DTO CO Et C 480 8 6 cvs DESCRIPTION Data Input Output Line 1 Data Input Output Line 2 Data Input Output Line 3 Data Input Output Line 4 End Or Identify Data Valid Not Ready For Data Not Data Accepted Interface Clear Service Request Attention Cable Shield Data Input Output Line 5 Data Input Output Line 6 Data Input Output Line 7 Data Input Output Line 8 Remote Enable Ground Wire Twisted pair with DAV Ground Wire Twisted pair with NRFD Ground Wire Twisted pair with NDAC Ground Wire Twisted pair with IFC Ground Wire Twisted pair with SRQ Ground Wire Twisted pair with ATN Logic Ground Figure 8 6 IEEE 488 Rear Panel Connector Details Service and Calibration 8 7 Lake Shore Model 480 Fluxmeter User s Manual 8 6 8 6 1 8 6 2 8 7 TOP OF ENCLOSURE REMOVAL AND REPLACEMENT WARNING To avoid potentially lethal shocks turn off controller and disconnect it from AC power line before performing this procedure Only qualified personnel should perform this procedure Removal Procedure Set power switch to Off O and disconnect power cord from rear of unit If attached remove 19 inch rack mounting brackets Use 5 64 hex key to remove four screws attaching top panel to unit Use 5 64 hex key to loosen four screws attaching bottom panel to unit Carefully remove the back bezel by sl
119. eters into the same non volatile memory used by Lake Shore probes The user coils act just like factory programmed probes after necessary information is loaded Coil parameters are entered using the coil setup feature and stored as described in Paragraph 5 3 and 5 6 For applications that require frequent changing of a few different coils up to ten sets of coil parameters can be stored in non volatile memory in the Model 480 After information is stored the coil select function is used to call it up Coil parameters are entered using the coil setup feature and stored as described in Paragraph 5 6 For applications where an absolute measurement in magnetic units is not required the Model 480 offers the units of percent This is intended to be a relative measurement for sorting operations of comparing values No knowledge of the coil is necessary to measure in percent If coil parameters are not known and the user has access to reference magnet or other known field the Model 480 can be used to calculate the required coil parameter for magnetic measurement units Refer to the coil calibrate feature Paragraph 5 5 for details Once a coil is calibrated the coil setup feature can be used to read the calibrated coil parameter Calibrated coil parameters can also be stored in instrument memory or a Model FCBL 6 accessory COIL SETUP The coil setup function allows the user to enter coil parameters for their coils Lake Shore coils and probes do not requi
120. f calibration but can still be used Reading values can be as much as 5 off Return the instrument to Lake Shore for recalibration Drift Adjust Failed The Auto Adjust feature was not able to compensate for the drift of the instrument Make sure the coil is properly connected to the instrument and the coil is not in a changing magnetic field Invalid Probe Data could not be read from or written to the probe Either no probe is attached to the instrument or the probe attached is not compatible with the Model 480 Fluxmeter Can Not Modify Lake Shore Probe A Lake Shore calibrated probe is attached to the instrument Coil parameters cannot be modified and data cannot be written to the probe LOCKED Keypad is locked Refer to Paragraph 5 14 to unlock the keypad Service and Calibration 8 9 8 9 8 9 1 8 9 2 8 9 3 Lake Shore Model 480 Fluxmeter User s Manual CALIBRATION PROCEDURE The first step of Model 480 calibration is to reset all the calibration parameters to nominal starting points This step is done for all ranges at one time by one command The second step obtains a Model 480 reading on a given range Third is the calculation of a corrective calibration constant for that given range from the Model 480 actual reading and an ideal reading derived from a digital voltmeter reading at the input of the Model 480 Forth stores the calibration constant in the proper location for the given range The process repeats through all ra
121. f any such defects during the Warranty Period and the defective Product is shipped freight prepaid 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 equipment 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 maintenance repair or calibration b fuses software power surges lightning and non rechargeable 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
122. ftTrak function to stop adjusting the DACs Too small a value and DriftTrak will never engage Too large a value and DriftTrak will mistake a measurement signal for drift The number is a 4 digit integer and the units are uV s min The default setting is 200 uV s min DRTHR Query DriftTrak Threshold Level Input DRTHR Returned nnnn Remarks Queries the threshold level of the DriftTrak function This is the rate of change that will cause the DriftTrak function to stop adjusting the DACs The number returned is a 4 digit integer and is the units of uV s min DRTRAK Configure DriftTrak Function Off On Input DRTRAK lt off on gt Returned Nothing Remarks Configures the DriftTrak function 0 Off 1 On The DriftTrak function continuously adjusts the drift correction DACs when the instrument is not taking a measurement to minimize drift DRTRAK Query DriftTrak Function Off On Input DRTRAK Returned 0 or 1 Format n term Remarks Queries the DriftTrak function O Off 1 On END Set End Or Identify EOI Parameter Input END lt EOI enable gt Returned Nothing Remarks Sets the EOI parameter lt EOI enable gt enables disables EOI 0 enabled 1 disabled When enabled the hardware EOI line becomes active with the last byte of a transfer The EOI identifies the last byte allowing for variable length data transmissions END Query End Or Identify EOI Parameter Input END Returned 0 or 1 Format n term
123. ften the largest source of error in integrating fluxmeters Drift is a slow change in reading when no change in flux exists It is caused by any small error voltage at the integrator input Manufacturers spend significant time and effort reducing the drift in instrument integrators Component type and value circuit board layout and manufacturing methods are all optimized to reduce drift Temperature change contributes so much to drift that critical components are often thermally isolated from other parts of the circuit Low drift is a result of good fluxmeter design but users can do things to maintain low drift 1 Use the instrument on the range specified for lowest drift 2 Attach sensing coil leads tightly and avoid unnecessary junctions or connections 3 Keep drafts or other temperature changes away from the coil lead contacts 4 Allow the instrument to warm up before drift is adjusted and adjust drift as often as practical during use 5 Reset the integrator often before every critical measurement if possible Some instruments have built in software algorithms that help adjust drift to zero before measurement Other algorithms work in a different way to cancel drift during measurement It is important to understand the difference and the affects on measurements Dielectric Absorption All capacitors exhibit a characteristic that can be described as a tendency to rebound from any fast change When capacitors are discharged to zero v
124. g Sets coil area turns for current coil in units of cm Enter up to 6 digits and a decimal point in exponential form Query Coil Area Turns COILAN t nnn nnnE tnn Returns coil area turns for current coil in units of cm Returns up to 6 digits and a decimal point in exponential form Initiate Coil Calibration COILCAL innn nnnEznn Nothing Calibrates the attached coil using the currently measured field This command only works in units of Vd Woo Mxo T G Wb cm or A The number part of the command is the value of the known field that is being used to calibrate the coil The coil must be in the field when the command is issued Configure Input Resistance COILINR lt resistance gt Nothing Configures the input resistance 0 0Q input 1 10kQ input 2 100kQ input Query Input Resistance COILINR 0 1 or 2 Format n term Queries the input resistance 0 0Q input 1 10kQ input 2 100kQ input Set Helmholtz Coil Constant COILKH nnn nnnE nn Nothing Sets Helmholtz coil constant for current coil in units of cm Enter up to 6 digits and a decimal point in exponential form Computer Interface Operation Lake Shore Model 480 Fluxmeter User s Manual COILKH Query Helmholtz Coil Constant Input COILKH Returned nnn nnnE nn Remarks Returns Helmholtz coil constant for current coil in units of cm Returns up to 6 digits anda decimal point in exponential form COILKP Set Potential Coil Co
125. g along a thin conducting material and an external magnetic field applied at right angles to the current Named for Edwin H Hall 1855 1938 an American physicist Hall mobility The quantity un in the relation UH Ro where R Hall coefficient and o conductivity Helmholtz coils A pair of flat circular coils having equal numbers of turns and equal diameters arranged with a common axis and connected in series used to obtain a magnetic field more nearly uniform than that of a single coil hertz Hz A unit of frequency equal to one cycle per second hole A mobile vacancy in the electronic valence structure of a semiconductor that acts like a positive electron charge with a positive mass hysteresis The dependence of the state of a system on its previous history generally in the form of a lagging of a physical effect behind its cause Also see magnetic hysteresis IEEE Institute of Electrical and Electronics Engineers IEEE 488 An instrumentation bus with hardware and programming standards designed to simplify instrument interfacing The addressable parallel bus specification is defined by the IEEE initial permeability The permeability determined at H 0 and B 0 initial susceptibility The susceptibility determined at H 0 and M 0 integrator A circuit or network whose output waveform is the time integral of its input waveform In the Model 480 the input is a voltage with the integral output being in volt seconds
126. graph 6 1 4 5 While the hardware and software required to produce and implement these programs not included with the instrument the concepts illustrated apply to almost any application where these tools are available 6 1 4 1 IEEE 488 Interface Board Installation for Visual Basic Program This procedure works for Plug and Play GPIB Hardware and Software for Windows 98 95 This example uses the AT GPIB TNT GPIB card 1 Install the GPIB Plug and Play Software and Hardware using National Instruments instructions 2 Verify that the following files have been installed to the Windows System folder a gpib 32 dll b gpib dll c gpib32ft dll Files b and c support any 16 bit Windows GPIB applications being used 3 Locate the following files and make note of their location These files will be used during the development process of a Visual Basic program a Niglobal bas b Vbib 32 bas NOTE If the files in Steps 2 and 3 are not installed on your computer they may be copied from your National Instruments setup disks or they may be downloaded from www ni com 4 Configure the GPIB by selecting the System icon in the Windows 98 95 Control Panel located under Settings on the Start Menu Configure the GPIB Settings as shown in Figure 6 1 Configure the DEV12 Device Template as shown in Figure 6 2 Be sure to check the Readdress box Computer Interface Operation 6 5 Lake Shore Model 480 Fluxmeter User s Manual System Properties 1x Genera
127. he Coil Setup key Press the Enter key until Enter Area Turns is displayed Use the numeric keypad to enter the area turns then press the Enter key The cursor will jump to a space before cm Use the a or v keys to select prefix _ Press the Enter key then the Escape key NOTE All the other settings Helmholtz Constant etc are ignored when using flux density units 8 Press the AC DC key until DC is displayed on the screen 9 Press the Peak Hold key until Peak Hold Off is displayed on the screen 10 Press the Range key Use the a or w keys to select the range appropriate to your measurement 11 Press the Reading Reset key 12 If the instrument has just been turned on allow it to warm up for at least 10 minutes before proceeding Otherwise proceed to Step 13 13 Press the Drift Adjust key Use the a or v keys until Begin Auto Adjust is displayed Press the Enter key You will see the following message ADJUSTING DRIFT For 25 Seconds 14 Make the test measurement 15 If the reading appears to be drifting refer to the Drift Adjust discussion in Paragraph 5 9 4 6 Basic Operation Lake Shore Model 480 Fluxmeter User s Manual 4 6 4 Moment Measurement In Unit of Wbcm Use the following procedure to take a moment measurement 1 Ensure power is turned Off O CAUTION Always turn off power to the Fluxmeter before making any rear panel PROBE INPUT or COIL INPUT connections 2 Attach the H
128. hen reading range is chosen the setting screen indicates the full scale range and resolution for the given coil and units During operation readings display in the resolution indicated when range is selected A plus or minus sign up to six digits a decimal point and appropriate prefix for each reading value If more than one zero leads the decimal point the zero does not display and digits are not added to increase resolution 4 4 KEYPAD DEFINITION C CJ CJ LICICICICI Mo YAA F 480 4 2 eps Figure 4 2 Model 480 Front Panel Peak Reset Resets Peak Hold hardware and peak reading stored in software Zeros the display reading Key is disabled if Peak Hold is turned off Peak Hold Turns Peak Hold feature ON or OFF Peak Hold can be turned on for any units and for DC and AC input Press and hold to select Peak Mode Range Selects the range of input signal The ranges are fixed in volt second units but all other ranges depend on coil characteristics Drift Adjust Selects one of three integrator drift adjustments Auto DriftTrak and Manual Press and hold to select threshold for DriftTrak Reading Reset Resets the analog integrator and zeros the display reading Key is disabled when in AC mode AC DC Selects AC or DC signal measurements In AC mode the integrator is modified slightly to reject the DC portion of the input signal Units Selects one of several measurement units Accurate measurements require knowledge of the attach
129. ic field strength H u B H Also see Initial Permeability and Differential Permeability polynomial fit A mathematical equation used to fit calibration data Polynomials are constructed of finite sums of terms of the form aix where ale the i fit coefficient and x is some function of the dependent variable pounds per square inch psi A unit of pressure 1 psi 6 89473 kPa Variations include psi absolute psia measured relative to vacuum zero pressure where one atmosphere pressure equals 14 696 psia and psi gauge psig where gauge measured relative to atmospheric or some other reference pressure ppm Parts per million e g 4 x 10 is four parts per million precision Careful measurement under controlled conditions which can be repeated with similar results See repeatability Also means that small differences can be detected and measured with confidence See resolution prefixes Sl prefixes used throughout this manual are as follows Factor Prefix Symbol Factor Prefix Symbol 10 yotta Y 107 deci d 10 zetta Z 10 centi CG 101 exa E 10 milli m 10 peta P 10 micro u 10 tera T 10 nano n 10 giga G 10 pico p 108 mega M 107 femto f 10 kilo k 1078 atto a 10 hecto h 10 zepto z 10 deka da 102 yocto y probe A long thin body containing a sensing element which can be inserted into a system in order to make measurements Typically the measurement is localized to the region near the tip of the probe remanence Th
130. ically installed in the instrument Archival 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 480 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 MS DOS and Windows 95 98 NT 2000 are trademarks of Microsoft Corp NI 488 2 is a trademark of National Instruments PC XT AT and PS 2 are trademarks of IBM Copyright O 1999 2001 2004 and 2014 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 Lake Shore Model 480 Fluxmeter User s Manual LE DECLARATION OF CONFORMITY We Lake Shore Cryotronics Inc 575 McCorkle Blvd Westerville OH 43082 USA hereby declare that the equipment specified conforms to the following
131. ico V or VI magnets for long term stability They are supplied in both transverse flat and axial configurations Typical flat reference magnets are usually stabilized for use at ambient temperatures between 0 50 C and have nominal temperature coefficients of about 0 02 C Because the temperature coefficient is negative the field strength will be reduced as the temperature rises Since these references are temperature cycled during manufacture their change with temperature is predictable and retraceable they will always return to a known value at any specific ambient temperature The high permeability shell which surrounds the reference magnet serves two function 1 it shields the magnet from external field and 2 serves as the flux return path Physical damage to the outer shell can cause a permanent change in the gap flux density Reference magnets should not be dropped or physically abused Magnets of this type can have magnetic reference values ranging from 100 G to 20 kG but the most widely used value is 1 kG Reference magnets accuracy is typically 0 5 except for magnets of 200 G or less for these magnets the limit of error is generally 1 The reference magnet gap is nominally 0 060 inch but may range from 0 040 to 0 250 inch for special units The usable plateau in the reference gap generally encompasses an area of about 0 5 square inches In reference magnets used for axial field probes Alnico V or VI is the usu
132. iding it straight back away from the unit Slide the top panel back and remove it from the unit 9 pi e ON a Installation Procedure Slide the top panel forward in the track provided on each side of the unit Carefully replace the back bezel by sliding it straight into the unit Use 5 64 hex key to install four screws attaching top panel to unit Use 5 64 hex key to tighten four screws attaching bottom panel to unit If required reattach 19 inch rack mounting brackets Connect power cord to rear of unit and set power switch to On I D m GO EPROM REPLACEMENT The operating software for the Model 480 is contained on one Erasable Programmable Read Only Memory EPROM Integrated Circuit IC The reference designator for the EPROM is U53 The EPROM has a sticker on top labeled with M480 HEX and the date Use the following procedure to replace the EPROM CAUTION The EPROM is an Electrostatic Discharge Sensitive ESDS device Wear shock proof wrist straps with a resistor that limits current to lt 5 mA to prevent injury to service personnel and to avoid inducing an Electrostatic Discharge ESD into the device Refer to Paragraph 8 2 Follow the top of enclosure REMOVAL procedure in Paragraph 8 6 1 2 Remove four Phillips head screws attaching transformer bracket to the Model 480 chassis Carefully pull transformer bracket up and sufficiently out of the way to gain access to the Operating Software EPROM See Figure 8 7 3
133. ing another person nearby capable of rendering aid If there is no power verify the power cord is plugged into a live outlet and that both ends are securely plugged in Next check the fuse see Paragraph 3 3 1 1 Use this procedure to periodically clean the Model 480 to remove dust grease and other contaminants 1 Clean front and back panels and case with soft cloth dampened with a mild detergent and water solution NOTE Do notuse aromatic hydrocarbons or chlorinated solvents to clean the Model 480 They may react with the plastic materials used in the controller or the silk screen printing on the back panel 2 Clean the surface of printed circuit boards PCBs with clean dry air at low pressure ELECTROSTATIC DISCHARGE Electrostatic Discharge ESD may damage electronic parts assemblies and equipment ESD is a transfer of electrostatic charge between bodies at different electrostatic potentials caused by direct contact or induced by an electrostatic field The low energy source that most commonly destroys Electrostatic Discharge Sensitive ESDS devices is the human body which generates and retains static electricity Simply walking across a carpet in low humidity may generate up to 35 000 volts of static electricity Current technology trends toward greater complexity increased packaging density and thinner dielectrics between active elements which results in electronic devices with even more ESD sensitivity Some electroni
134. instrument Device number used with IEEE Show main window Terminators are lt CR gt lt LF gt Clear return string Initialize the IEEE device Setup Repeat Addressing Wait loop Give up processor to other events Loop until Send button pressed Set Flag as False Get Command Clear response display Set all characters to upper case Get out on EXIT Send command to instrument Check for IEEE errors Handle errors here Check to see if query Build empty return buffer Read back response Check for IEEE errors Handle errors here Check if empty string Remove extra spaces and Terminators Do While Right strReturn 1 Chr 10 Or Right strReturn 1 Chr 13 strReturn Left strReturn Len strReturn 1 Loop Else strReturn No Response Send No Response End If frmIEEE txtResponse Text strReturn End If Loop End Sub Put response in text on main form Computer Interface Operation Lake Shore Model 480 Fluxmeter User s Manual 6 1 4 3 IEEE 488 Interface Board Installation for Quick Basic Program This procedure works on an IBM PC or compatible running DOS or in a DOS window This example uses the National Instruments GPIB PCII IIA card 1 Install GPIB PCII IIA card using National Instruments instructions Install NI 488 2 software for DOS Version 2 1 1 was used for the example Verify that config sys contains the command device gpib pc gpib com Reboot the computer
135. isplay Resolution 4 digits AC Integrator Capacitance 0 1 uF nominal AC Input Resistance 100 kQ AC Ranges 30 mVs 3 mVs 300 uVs 30 uVs AC Resolution 0 001 mVs 0 0001 mVs 0 01 uVs 0 01 uVs AC Min Rdg 3 000 mVs 0 3000 mVs 30 00 uVs 3 00 Vs AC Frequency Response 2 Hz to 50 kHz see Figure 5 1 AC Accuracy 1 of reading 10 uVs 10 Hz 10 kHz sinusoidal 15 of reading 10 uVs 2 Hz 50 kHz sinusoidal AC Integrator Drift N A AC Peak AC Peak Display Resolution 3 digits AC Peak Integrator Capacitance 0 1 uF nominal AC Peak Input Resistance 100 kQ AC Peak Ranges 30 mVs 3 mVs 300 uVs AC Peak Resolution 0 01 mVs 0 001 mVs 1 us AC Peak Min Reading 0 01 mVs 0 001 mVs 5 uVs AC Peak Accuracy 5 of reading 10 uVs 10 Hz 10 kHz sinusoidal 10 of reading 10 uVs 2 Hz 50 kHz sinusoidal AC Peak Update Rate May reduce update rate to 1 4 normal Front Panel Display Type Two line by 20 character vacuum fluorescent display Display Resolution To 5 digits Display Update Rate 5 readings per second Display Units Vs MxN WbN Vso Mxo Who G T Wbcm A Units Multipliers p n u m k M G i AC input signal DC input signal Positive and Negative peaks Remote Operation d Alarm on Keypad 21 full travel keys AV 1 2 Introduction Lake Shore Model 480 Fluxmeter User s Manual Specifications Continued Interfaces IEEE 488 2 Capa
136. itive peak range location per Table 8 2 from the computer using the form CALGAIN lt location gt lt x xxxxxe x gt 23 Send the same Calibration Constant to the appropriate negative peak range location per Table 8 2 from the computer using the form CALGAIN lt location gt lt x xxxxxe x gt 24 Repeat Steps 5 thru 24 for each range of Table 8 2 until all DC ranges are calibrated Output Calibration The Model 480 output calibration consists of monitor and corrected output calibrations detailed in Paragraphs 8 9 7 1 and 8 9 7 2 Monitor Output Calibration 1 Connect Oscillator to Model 480 input terminals observe ground using the 1 uF series capacitor in series with the signal lead Connect DVM to Model 480 Monitor Output set to AC Set Model 480 to AC 100 kQ input resistance 30 mV s range non peak operation Set oscillator to 5 655 Vrms 60 Hz sine continuous Calculate Ideal Monitor Vrms Model 480 reading x 100 s nominal 1 5 Vrms Calculate Monitor Gain Constant Ideal Monitor Vrms Actual Monitor Vrms ES Send Monitor Gain Constant to appropriate location using the CALDAC lt xxxxxx gt command Note This value must be between 0 8 and 1 0 A value outside this range indicates a major malfunction of the Model 480 that requires repair Service and Calibration 8 13 Lake Shore Model 480 Fluxmeter User s Manual 8 9 7 2 Corrected Output Calibration Connect DVM to Model 480 Corrected
137. ke Shore Model 480 Fluxmeter User s Manual APPENDIX B REFERENCE INFORMATION Table B 1 Conversion from CGS to SI Units Quantit Gaussian Conversion SI amp Pally amp CGS emu Factor CH Rationalized mks d Magnetic flux density G tesla T Wb m Magnetic induction ar a weber Wb volt Magnetic Flux A maxwell Mx Gem second V s ee a eg gilbert Gb GER ampere A Magnetic field strength 3 f magnetizing force oersted Oe Gb cm 109 47 A m Volume magnetization Alm M Volume magnetization 4nM 103 47 A m RE emu cm An x 10 4 T Wb m2 magnetization 1 A m kg izati emu ar emu erg G 103 Am joule per Magnetic dipole momen Wb m Volume energy density erg cm 107 Um Demagnetization factor Relative permeability 3 3 Mass susceptibility m g emu g feel 0 10 sc E dimensionless Henry per meter Volume susceptibility 4n 2 x 107 H m Wb A m c gt 6 3 Molar susceptibility cm mol emu mol be pan aome H m Wb A m not defined dimensionless Permeability energy Droduch dimensionless dimensionless NOTES a b c se mee k Gaussian units and cgs emu are the same for magnetic properties The defining relation is B H 47M Multiply a number in Gaussian units by C to convert it to SI e g 1 G x 104T G 10 T SI Syst me International d Unit s has been adopted by the National Bureau of Standards Where two conversion factors are given
138. l l Use the a or w keys to cycle through the storage locations 1 10 When you reach the desired coil location press the Enter key or press the Escape key to cancel and return to the normal display Storing New Coil Parameters into Probe Memory The Lake Shore Model FCBL 6 User Programmable Coil Interconnect Cable is designed to allow a customer to mate an in house designed coil to the Model 480 Fluxmeter taking full advantage of the internal PROM programming capability Connect the FCBL 6 to the user coil per instruction in Paragraph 3 5 1 Turn the instrument Off O and connect the FCBL 6 to the PROBE INPUT connector at the rear of the instrument Turn power On I Push the Coil Setup key and enter all relevant coil parameters as detailed in Paragraph 5 3 This accomplished press and hold the Coil Select key You will see the following display Se ect Wi th at Save Coil Probe Use the a or v keys to select PROBE Press the ENTER key or press the Escape key to cancel and return to the normal display After the PROM is loaded with the necessary coil parameters nothing more is required for future use of that coil except to turn off the Model 480 attach the cable and turn power back on Selecting Saved Coil Parameters To select the parameters of a coil that were previously saved in instrument memory press the Coil Select key You will see the following display Sel ect With 47 Se
139. l 480 Fluxmeter User s Manual DRIFT ADJUSTMENT Drift Adjustment is a fact of life when making DC and DC Peak measurements with an analog integrator like the one in the Model 480 Drift is caused by offsets present in the integrator components and coil connections AC and AC Peak measurements do not require drift adjustment because modifications to the integrator bring the reading to zero when no signal is present Drift is related to instrument hardware and often temperature change The Model 480 has been designed to minimize drift but there are some important things to do during setup when low drift is important 1 Let the instrument warm up before attempting to adjust drift Allow 30 minutes for normal use and longer if the instrument is stored in an unheated area Attach the coil that will be used with the fluxmeter before drift is adjusted Make sure coil connections are tight Keep coil leads as short as possible and have as few connections as possible OP AO Shield coil contacts from fast temperature changes The Model 480 has replaced the drift adjustment trim potentiometer present on older fluxmeters with two internal digital to analog converters DACs for drift compensation These converters can be set from the keypad for very precise manual drift adjustment or controlled by the instrument for hands off drift adjustment The paragraphs below describe three ways to adjust drift with the Model 480 All drift adjustments must be ma
140. l Device Manager Hardware Profiles ee GPIB TNT Plug and Play Properties HE i General GPIB Settings Resources View devices by type View devices by col Si Computer Y AT GPIB TNT Plug and Play E e CDROM Disk drives ISA PnP Serial Number 004D7F40 a Display adapters o GH Floppy disk controllers Interface Name m Termination Methods Hard disk controllers leen y Y Send EOI at end of Write z Keyboard e i Monitor GPIB Address IV Terminate Read on EOS Mouse Primary i il E National Instruments GPIB Interfaces bg Set EDI wah EOS on its AT GPIB TNT Plug and Play I 8 bit EOS Compare K Network adapters Secondary 4 Ports COM amp LPT 10 EOS Byt NONE d Bute o BR System devices 120 Timeout gt 10sec y Properties Refresh Remove IV System Controller OK Cancel Figure 6 1 GPIBO Setting Configuration System Properties General Device Manager Hardware Profiles Performance View devices by type eden National Instruments GPIB Interfaces Properties 27 x General Device Templates m Computer H CDROM l 1 3 Disk drives y National Instruments GPIB Interfaces aj Display adapters Floppy disk controllers Hard disk controllers Device Name z Keyboard CO RI Monitor Mouse
141. lity e RL1 Complete remote local capability e DC1 Full device clear capability DTO No device trigger capability e CO No system controller capability e T5 Basic TALKER serial poll capability talk only unaddressed to talk if addressed to listen e L4 Basic LISTENER unaddressed to listen if addressed to talk e SR1 Service request capability AH1 Acceptor handshake capability PPO No parallel poll capability e El Open collector electronics Computer Interface Operation 6 1 Lake Shore Model 480 Fluxmeter User s Manual 6 1 1 IEEE 488 Interface Settings If using the IEEE 488 interface you must set the IEEE Address and Terminators Press the Interface key The first screen selects Serial Interface Baud Rate and therefore is skipped by pressing the Enter key The Address screen is then displayed Sel ect hli th aF TEEE Address l1 2 Press the s or t keys to increment or decrement the IEEE Address to the desired number Press Enter to accept new number or Escape to retain the existing number Pressing Enter displays the Terminators screen Sel ect hli th aF Term Cr Lf Press the s or t keys to cycle through the following Terminator choices CR LF LF CR LF and EOI To accept changes or the currently displayed setting push Enter To cancel changes push Escape Power down the Model 480 then back up again to allow other devices on the IEEE 488 bus to recognize a new Addres
142. measurement proportional to the magnetic moment of a permanent magnet as defined in the CGS System If the Helmholtz coil constant is known magnetic moment can be accurately determined Uncalibrated coils provide reliable comparative data Magnetometers like a vibrating sample magnetometer VSM also make moment measurements but usually of much smaller values Important Parameters of A Helmholtz Coil For predictable permanent magnet measurements with a Helmholtz coil the physical dimensions of the coil must be controlled A Helmholtz coil is two parallel coils spaced so the average diameter of the coils is twice the distance between their central planes No dimension of the coil cross section should exceed 10 of the coil diameter Coil diameter should be three to five times the maximum dimension of the part under evaluation An empirically derived calibration constant Kh in centimeters is often provided with the coil to allow a fluxmeter to operate in Wb cm a more convenient form of the SI unit Wb m where Wb m Wb cmx100 Magnetic Measurement Overview 2 11 Lake Shore Model 480 Fluxmeter User s Manual 2 5 3 Helmholtz Coil Constant Determination For Non Lake Shore Coils To use a Helmholtz coil and the Model 480 Fluxmeter to make magnet moment measurements a Helmholtz Coil Constant is required Regretfully this parameter is rarely available Either the coil is made in house or the vendor supplies a coil sensitivity flux density
143. n Input ALARM Returned 0 or 1 Format n term Remarks Queries the alarm function 0 Off 1 On ALMB Configure Audible Alarm Beeper Input ALMB lt off on gt Returned Nothing Remarks Configures the audible alarm beeper 0 Off 1 On ALMB Query Audible Alarm Beeper Input ALMB Returned 0 or 1 Format n term Remarks Queries current audible alarm status 0 Off 1 On ALMH Set Alarm High Point Value Input ALMH nnn nnnE nn Returned Nothing Remarks Sets the high point of the alarm function Enter up to 6 digits with decimal point in exponential form Place decimal appropriate to range ALMH Query Alarm High Point Value Input ALMH Returned nnn nnnE nn Remarks Returns the high point of the alarm function up to 6 digits with decimal point in exponential form ALMIO Configure Alarm Trigger Outside Inside Input ALMIO lt out in gt Returned Nothing Remarks Configures the alarm trigger outside inside function 0 Outside 1 Inside This setting determines whether readings inside or outside the defined magnetic field range trigger the alarm ALMIO Query Alarm Trigger Outside Inside Input ALMIO Returned 0 or 1 Format n term Remarks Queries the alarm trigger inside outside function 0 Outside 1 Inside This setting determines whether readings inside or outside the defined magnetic field range trigger the alarm 6 24 Computer Interface Operation ALML Input
144. n Lake Shore Model 480 Fluxmeter User s Manual 6 1 4 5 Program Operation Once either example program is running try the following commands and observe the response of the instrument Input from the user is shown in bold and terminators are added by the program The word term indicates the required terminators included with the response ENTER COMMAND IDN Identification query Returns an identification string RESPONSE LSCI MODEL480 1234567 02032004 term ENTER COMMAND READ Reading query Returns reading in the form XXX XX RESPONSE 273 150E 00 term Decimal point is placed appropriate to range ENTER COMMAND RNGDC DC Range Query Returns appropriate range 0 where 0 300 mV s and 1 30 mV s ENTER COMMAND UNITS Units query Returns an integer from 1 to 11 corresponding 1 to the units being used In this example 1 V s ENTER COMMAND ACDC AC or DC query Returns appropriate setting 0 where 0 DC and 1 AC ENTER COMMAND FILT Filter query Returns appropriate setting 0 where 0 Off and 1 On ENTER COMMAND FILT 1 FILT Turns filter on then returns a 1 to verify the change 1 ENTER COMMAND The following are additional notes on using either IEEE 488 Interface program e If you enter a correctly spelled query without a nothing will be returned Incorrectly spelled commands and queries are ignored
145. n cccnc cides tessa deat dietas 2 3 2 1 6 Analog Versus Digital Integrators AA 2 4 2 1 7 Fluxmeter Measurements in MaQnetiZers cccceeeeeeeceeeenneeeeeenaeeeeeeaaeeeeeeaaeeeeeeaeeeeeeaaes 2 4 2 1 8 Making AC Measurements scenes ceaeeesaaeedeaeeseeeeesaeeesaeeeeneeee 2 6 2 2 COILCHARACTERIS TO S a 2 6 2 2 1 COIlSEnSitiVity EE 2 6 2 2 2 A EE 2 7 2 2 3 e Ne E TEE 2 7 2 2 4 Coil Temperature Coefficient ceccccccceeeeeeeceeeeeceeeeeeeaeeeeeeeseeeesaeeesaaeseeeeeseeessaeeneneeee 2 8 2 2 5 Gol Orientation piesa teenie bia hi ena ead Meee eee 2 8 2 2 6 FIS UNO e EE 2 9 2 2 7 Lead PiCkUP ET 2 9 2 2 8 Inductance Capacitance and Self RESONANCE ese ccecssececeeseeeeceeneeeeecaeeeesssateeeeeaaes 2 9 2 2 9 Lake Shore Coils and Probes ccccccseeceeeeeceeeeeeeaeeeeaeeeeeeeecaeeeseaeeeeneeseeeeessaeeesaeeeenetee 2 9 2 3 FEUX OVERVIEW EE 2 10 2 4 FLUX DENSITY OVERVIEW Gota tie ee adhere ed 2 10 2 4 1 Whats Flux Density tutti diarias 2 10 2 4 2 How Flux Density B Differs from Magnetic Field Strength H 2 11 2 5 MAGNETIC MOMENT OVERVIEW oooocccnnocccoccccconcnonononononcconcnnonnnnnnn nn nnnc cnn rca rana 2 11 2 5 1 What is Magnetic Moment dmca tenias 2 11 2 5 2 Important Parameters of a Hemholtz Col 2 11 2 5 3 Hemholtz Coil Constant Determination For Non Lake Shore Colle 2 12 2 6 MAGNETIC POTENTIAL OVERVIEW nn nn ccrn rra 2 13 2 6 1 What is Magnetic Potential ccccceccecseeeceeceeceeeeeceaeeeeaees
146. n a non periodic way With only slight modifications to the integrator a fluxmeter can measure periodic AC fields AC measurements are useful in measuring stray fields around transformers or the poles of a rotating magnet A simple expression for a sinusoidal AC flux p t as it varies with time is o t On sin 27 ft where Qmax is the maximum amplitude of flux f is the frequency and t is time The voltage generated by a sense coil in a field changing this way is proportional to the derivative of the field Ke yo x N2nfo cos 27ft t Note that coil voltage amplitude depends on frequency f and flux amplitude pmax The integrator in the instrument reverses the action of the coil and removes the direct frequency dependence N ND F 3 7 dt N2T S 0 ax Sin 2ft CH KC SC The integrator output voltage can be processed by a peak detector to find max or through an RMS converter to find the RMS flux value The relationships hold true for non sinusoid AC fields also Vue lt fonn cos 21 ft dt The above discussion assumes that the coil inductance and capacitance are small and that the frequency band of the instrument is not exceeded Refer to Paragraph 2 2 8 for more details COIL CHARACTERISTICS One reason fluxmeters are popular is the low cost and simple construction of sensing coils Some coils are as simple as a few turns of copper wire Coil construction gets more complicated to meet special measu
147. n the measured value is between the setpoints Relay operation ignores the Inside Outside parameter Relay terminals are located in the detachable terminal block on the rear panel of the instrument With On or Off modes the relays can be controlled manually for testing hardware or to control external devices unrelated to alarm function To set relay status press the Alarm Setup key You will see the Enter High Alarm display Press the Enter key until you see the High Relay display Sel ect Wi th aF Hi 9h Rel au OF f Use the a or v keys to cycle between On Off and Auto Once selected press the Enter key You will see the next display On indicates an active relay state while O indicates a normal relay state Se ect Wi th 4F Mi ddl e Rel ast OT 5 18 Advanced Operation Lake Shore Model 480 Fluxmeter User s Manual Relay Setup Continued 5 14 3 Use the a or v keys to cycle between On Off and Auto Once selected press the Enter key You will see the next display Sel ect Wi th aF Low Rel 39 Aa Use the a or v keys to cycle between On Off and Auto Once selected press the Enter key The screen will return to the normal display Turning Alarm On and Off Once the alarm feature is setup it can be activated conveniently with a single key Press the Alarm On Off key to turn the alarm feature on or off The music note annunciator
148. nced Operation 5 11 Lake Shore Model 480 Fluxmeter User s Manual DriftTrak Continued To turn the DriftTrak algorithm on or off press the Drift Adjust key The message Begin Auto Adjust will appear Use the A or Y keys until the Set DriftTrak message appears Se ect Wi th aF Set Dri ft Trak Press the Enter key You now see the DriftTrak On Off display Se ect Wi th aF Dri ft Trak 0n Use the A or Y keys to toggle between DriftTrak On or Off Press the Enter key The instrument will return to the normal display To set the DriftTrak threshold press and hold the Drift Adjust key until you see the following display Enter Threshol d 2496 HL Ss mi n Use the numeric keypad to enter the DriftTrak threshold in uV s minute then press the Enter key The instrument will return to the normal display 5 10 DC AND AC MEASUREMENT MODES The Model 480 can be used to measure non repetitive field changes in DC mode or repetitive field changes in AC mode These measurements are different and many sections in this chapter differentiate between DC and AC operation 5 10 1 DC Measurement Mode DC measurement are the most common type of magnetic measurement associated with fluxmeters Permanent magnet testing and sorting are often done in DC mode Magnet characterization in an electromagnet system requires good DC performance The peak hold should be used with DC mode for pass through magnet
149. nel connections This is especially critical when making probe to instrument connections 2 3 4 5 6 7 8 NO H MNC LNO LCOM LNC gt 9 n 12 13 14 15 16 MNO MCOM MNC RST oun OPT OOR oe PROBE INPUT oooooooo QUAY O CAUTION POWER BFF TO MATE PROBE F 480 3 1 eps Description Pin Definition O Line Input Assembly Paragraph 3 3 Figure 3 2 SERIAL I O Connector Paragraph 6 2 Figure 8 5 COIL INPUT Banana Jacks Paragraph 3 4 Figure 8 2 PROBE INPUT Connector Paragraph 3 5 Figure 8 3 Terminal Block Paragraph 3 6 Figure 8 4 IEEE 488 INTERFACE Connector Paragraph 6 1 Figure 8 6 Figure 3 1 Model 480 Rear Panel 3 3 LINE INPUT ASSEMBLY 3 3 1 3 3 2 3 3 3 This section covers line voltage and fuse verification in Paragraph 3 3 1 power cord in Paragraph 3 3 2 and power switch in Paragraph 3 3 3 Line Voltage and Fuse Verification To verify proper line voltage selection look at the indicator in the window of the line input assembly Line voltage should be in the range shown in the specifications listed on the back of the instrument See Figure 3 2 If not change the line voltage selector per instructions in Paragraph 8 3 The fuse must be removed to verify its value refer to the procedure in Paragraph 8 4 Use slow blow fuses of the value specified on back of the instrument Power Cord The Model 480 includes a three conductor power cord Line voltage is presen
150. ng two Y rack fluxmeters in 482 6 mm rack 4004 IEEE 488 cable 1 meter 119 028 Model 480 User s Manual 106 739 Terminal Block Mating Connector 8 pin quantity 2 Probes and Coils ordered separately FNT 6R04 100 Field Probe 100 cm FNT 5R04 30 Field Probe 30 cm FH 2 5 Helmholtz Coil 2 5 inch 1 D FH 6 Helmholtz Coil 6 inch 1 D FH 12 Helmholtz Coil 12 inch 1 D FCBL 6 User Programmable Cable with PROM 6 feet long Custom probes coils fixtures available consult Lake Shore for more information Accessories options included with a new Model 480 Introduction 1 3 1 3 1 4 Lake Shore Model 480 Fluxmeter User s Manual SAFETY SUMMARY Observe these general safety precautions during all phases of instrument operation service and repair Failure to comply with these precautions or with specific warnings elsewhere in this manual violates safety standards of design manufacture and intended instrument use Lake Shore assumes no liability for Customer failure to comply with these requirements The Model 480 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 Indoor use e Altitude to 2 000 meters e Temperature for safe operation 5 C to 40 e Maximum relative humidity 80 for temperatu
151. nges of the Model 480 Monitor and Corrected Analog outputs are done in a similar fashion The operation of the Model 480 is handled manually from the front panel but the actual placing of derived calibration data in appropriate memory locations is handled solely by the computer interface Although this procedure describes field calibration of the Model 480 it is highly recommended that the unit be returned to Lake Shore for periodic calibration Required Equipment List 1 Computer with communication interface established with Model 480 Can be accomplished by either RS 232 or IEEE 488 Interface and cable 2 Digital Voltmeter Basic DC accuracy 0 01 AC accuracy 0 5 5 Hz to 50 kHz sine wave Suggested Hewlett Packard Model HP34401A 3 Oscillator 0 1 Hz to 50 kHz sine burst mode square wave amplitude accuracy 2 frequency accuracy 0 01 output impedance 50 Q Suggested Hewlett Packard HP33120 4 1 uF 50 V non polar mylar or polypropylene capacitor to be connected in series with the oscillator signal lead during AC calibration The actual accuracy of the capacitor is not a major issue since the digital voltmeter is used to actually measure the voltage at the Model 480 terminals Used in AC calibrations 5 100 1 Resistive Attenuator series 10 1 kQ resistor with shunt 102 resistor suggested to be connected between the oscillator output and Model 480 input The actual accuracies of the resistors are not a major issue since
152. ning Basic There must be QBIB QBL library in the QuickBasic Directory and QuickBasic must start with a link to it All instrument settings are assumed to be defaults Address 12 Terminators lt CR gt lt LF gt and EOI active To use type an instrument command or query at the prompt The computer transmits to the instrument and displays any response If no query is sent the instrument responds to the last query received Type EXIT to exit the program REM SINCLUDE c gpib pc qbasic qbdecl bas CLS PRINT IEEE 488 COMMUNICATION PROGRAM PRINT CALL IBFIND dev12 DEV12 TERMS CHR 13 CHR 10 INS SPACES 2000 LINE INPUT ENTER COMMAND or EXIT CMD CMD UCASES CMD IF CMDS EXIT THEN END CMD CNDS TERMS CALL IBWRT DEV12 CMDS CALL IBRD DEV12 INS ENDTEST INSTR INS CHR 13 IF ENDTEST gt 0 THEN INS MID IN 1 ENDTEST 1 PRINT RESPONSE INS ELSE PRINT NO RESPONSE END IF GOTO LOOP2 Link to IEEE calls Clear screen Open communication at address 12 Terminators are lt CR gt lt LF gt Clear for return string Get command from keyboard Change input to upper case Get out on Exit Send command to instrument Get data back each time Test for returned string String is present if lt CR gt is seen Strip off terminators Print return string No string present if timeout Get next command 6 12 Computer Interface Operatio
153. nstant Input COILKP nnn nnnE nn Returned Nothing Remarks Sets potential coil constant for current coil in units of A V s Enter up to 6 digits and a decimal point in exponential form COILKP Query Potential Coil Constant Input COILKP Returned nnn nnnE nn Remarks Returns potential coil constant for current coil in units of A V s Returns up to 6 digits and a decimal point in exponential form COILN Set Coil Number Of Turns Input COILN nnn nnnE nn Returned Nothing Remarks Sets number of turns for current coil in units of turns Enter up to 6 digits and a decimal point in exponential form COILN Query Coil Number Of Turns Input COILN Returned nnn nnnEtnn Remarks Returns number of turns for current coil in units of turns Returns up to 6 digits and a decimal point in exponential form COILNUM Configure Coil Number Parameter Input COILNUM lt coil number gt Returned Nothing Remarks Configures unit for a set of stored coil parameters 1 10 internally stored coil parameters 11 probe data COILNUM Query Coil Number Parameter Input COILNUM Returned An integer from 0 to 11 Format nn term Remarks Returns the number of the coil parameters currently loaded 0 user coil modified coil 1 10 internally stored coil parameters 11 probe data COILR Set Coil Resistance Input COILR nnn nnnE tnn Returned Nothing Remarks Sets coil resistance for current coil in units of ohms Q This is the DC resi
154. nt in exponential form Place decimal appropriate to range Query Analog Out High Point Value ANOH t nnn nnnE nn Returns the high point of the analog out function in user mode up to 6 digits with decimal point in exponential form Set Analog Out Low Point Value ANOL nnn nnnE nn Nothing Sets the low point of the analog out function in user mode Enter up to 6 digits with decimal point in exponential form Place decimal appropriate to range Computer Interface Operation Lake Shore Model 480 Fluxmeter User s Manual ANOL Query Analog Out Low Point Value Input ANOL Returned nnn nnnE nn Remarks Returns the low point of the analog out function in user mode up to 6 digits with decimal point in exponential form ANOM Configure Analog Out Mode Input ANOM lt mode gt Returned Nothing Remarks Configures analog out mode 0 Default 1 User 2 Manual ANOM Query Analog Out Mode Input ANOM Returned 0 1 or 2 Format n term Remarks Queries analog out mode 0 Default 1 User 2 Manual BAUD Configure Serial Interface Baud Rate Input BAUD lt bps gt Returned Nothing Remarks Configures the serial interface baud rate lt bps gt specifies bits per second bps rate 0 300 1 1200 2 9600 BAUD Query Serial Interface Baud Rate Input BAUD Returned lt bps gt Format n term Remarks Returns serial interface baud rate Refer to BAUD command for parameter descriptions BRIGT Set F
155. nts Lake Shore Model 480 Fluxmeter User s Manual LIST OF ILLUSTRATIONS Figure No Title Page 3 1 Model 480 Rear Palito Ads 3 2 3 2 Line ele EE 3 3 4 1 Model 480 Normal Display Definition oooonoccccnnnnccccnonoccccnononnnccnnoncnncnno cnn n nano cnn r nan nn r nar nn rr rnnr rca 4 1 4 2 Model 480 Front Panelis cito ci a aiaiai dd a di 4 2 5 1 Model 480 AC Frequency Response occcccccccccocccononcnonoccconcnnnnnnnnnn nn nan nc cnn n anar n naar rn narra narra anar nnnnccns 5 13 5 2 Examples of Alarm Activation Inside and Outside High and Low Setpoints ooococncnnnnnnnncnnncccc 5 18 6 1 GPIBO Setting Configuration nc cnn narran 6 6 6 2 DEV 12 Device Template Configuration ooocncccnnnnnnnnnnnncccnocccnnorna narran nn 6 6 6 3 Typical National Instruments GPIB Configuration from IDBCONF ENEE 6 11 7 1 1006m Field Premia A a a ae a AA 7 3 7 2 DOCM Pr is 7 4 7 3 Model FH 2 5 Helmholtz Col 7 5 7 4 Model FH 6 Helmholtz Col 7 6 7 5 Model FH 12 Helmholtz Co 7 6 7 6 Lake Shore Reference Magnets oooococinocccnnccccocccoconanonocononcnnonn cnn anna cerraran rana 7 7 7 7 Model RM 1 2 Halt Hack Mounting ki 7 8 7 8 Model RM 2 Dual Rack Mount Shelf c ccccccecceeceeeeeeeeeeceeeeeaaeeeeaeeseeeeseaeseeaaeseeeeeseeeesaeeseeeseaes 7 8 8 1 Power EE 8 3 8 2 COIL INPUT Connector Details cc ccceeceeeeeeeeeeeeeeeeee cece eeeaeeeeaeeseeeeesaeeesaaeedeaeeseeeesaeeesaeeeeeeeeed 8 4 8 3 PROBE INPUT Connector Details 8 4 8
156. o Continue WAI Nothing Prevents execution of any further commands or queries until completion of all previous ones Changing the sample sensor and reading it immediately with a device dependent query may result in a reading error because the sensor needs time to stabilize Place a WAI between the sensor change and query for a correct reading Achieve the same results with repeated queries or using a Service Request but WAI is easier Send WAI as the last command in a command string followed by appropriate termination It cannot be embedded between other commands Configure AC or DC Magnetic Field Reading Parameter ACDC lt acdc gt Nothing Configures the unit for AC or DC measurements lt acdc gt specifies mode 0 DC 1 AC Query AC or DC Magnetic Field Reading Parameter ACDC 0 or 1 Format n term Returns the AC or DC measurement mode 0 DC 1 AC Configure IEEE Address ADDR lt address gt Nothing Configures IEEE address lt address gt an integer from 1 to 30 The Model 480 is factory preset to 12 Query IEEE Address ADDR lt address gt Format nn term Returns the current IEEE address The Model 480 is factory preset to 12 Computer Interface Operation Lake Shore Model 480 Fluxmeter User s Manual ALARM Configure Alarm Function Off On Input ALARM lt off on gt Returned Nothing Remarks Configures the alarm function 0 Off 1 On ALARM Query Alarm Function Off O
157. obe with a PROM attachment Lake Shore part FCBL 6 is required for this function Enter up to 10 characters for a serial number and enter a date in the form mmddyyyy month day year This command does not save the information to the probe itself The COILSAVE command must be used to save the serial number date and coil parameters to the probe PROBE User 5 12291998 sets the serial number to User 5 and the date to 12 29 1998 Query Probe Serial Number and Date PROBE lt serial number gt lt date gt Format aaaaaaaaaa nnnnnnnn Returns the serial number and date for the probe attached during power up If a new probe is attached cycle the power to load new probe data A probe with a PROM attachment Lake Shore part FCBL 6 or a Lake Shore probe is required for this function Returns 10 characters for a serial number and returns a date in the form mmddyyyy month day year Computer Interface Operation Lake Shore Model 480 Fluxmeter User s Manual RDRST Initiate Reading Reset Command Input RDRST Returned Nothing Remarks In DC mode resets the reading of the unit to zero Does not function in AC mode READ Query Present Display Reading Input READ Returned nnn nnnE nn Remarks Returns the present reading in exponential form in the currently selected units RELAYH Configure High Relay Function Input RELAYH lt mode gt Returned Nothing Remarks Configures the high relay function 0 Manual Off 1
158. of nominal value 3 96cm 1 56 O D 0 79 cm 0 31 d a min working space 5 6 cm 2 19 Axial 0 312 diameter working space MRA 312 100 within 1 of nominal value MRA 312 200 within 1 of nominal value MRA 312 500 within 1 of nominal value P 480 7 6 bmp Figure 7 6 Lake Shore Reference Magnets Accessories Coils and Probes 7 7 Lake Shore Model 480 Fluxmeter User s Manual Item Description Rack Mount Ear Rack Mount Support Rack Mount Panel Rack Mount Handle Screw 6 32 x 1 2 Inch FHMS Phillips Screw 8 32 x 3 8 Inch FHMS Phillips Figure 7 7 Model RM 1 2 Half Rack Mounting Kit P Refer to Es Installation Procedure ep R side of Fluxmeter Installation Procedure NOTE Remove four Model 480 side screws with 5 64 in 2 mm hex key Drawing shows right side mounting Left side mounting also possible 107 440 1 107 442 1 107 051 01 1 107 433 2 0 035 4 0 081 C 480 7 7 eps 1 Use 5 64 inch 2 mm hex key to remove two 6 32 x 1 4 black button head screws from 2 Place Fluxmeter on shelf 3 Use 5 64 inch 2 mm hex key to reinstall two 6 32 x 1 4 black button head screws through side of rack into corresponding holes in the side of the Fluxmeter Figure 7 8 Model RM 2 Dual Rack Mount Shelf C 480 7 8 eps 7 8 Accessories Coils and Probes 8 0 8 1 8 2 Lake Shore Model 480 Fluxmeter User s Manual CHAPTER 8 SERVICE AND CALIBRATI
159. of steps American Standard Code for Information Exchange ASCII A standard code used in data transmission in which 128 numerals letters symbols and special control codes are represented by a 7 bit binary number as follows JOJON DU A umi O w Yu rn lt ix E lt ic Aju mjojo um 1 Q O O o O O 0 10 1 1 1 1 1 1 1 1 alle Glen Lal leo leo H a ajofjo fojo fojo ojo g Oo Joj fo fofj O O O0 f0 2 OS SIF Alc nr jommo o 3 3 x gt bo alo jajo ojala o o de JIN lt x j lt je pe jajoj N E YY ITAT American Wire Gage AWG Wiring sizes are defined as diameters in inches and millimeters as follows AWG Dia In Dia mm AWG Dia In Dia mm AWG Dia In Dia mm AWG Dia In Dia mm 1 0 2893 7 348 11 0 0907 2 304 21 0 0285 0 7230 31 0 0089 0 2268 2 0 2576 6 544 12 0 0808 2 053 22 0 0253 0 6438 32 0 0080 0 2019 3 0 2294 5 827 13 0 0720 1 829 23 0 0226 0 5733 33 0 00708 0 178 4 0 2043 5 189 14 0 0641 1 628 24 0 0207 0 5106 34 0 00630 0 152 5 0 1819 4 621 15 0 0571 1 450 25 0 0179 0 4547 35 0 00561 0 138 6 0 1620 4 115 16 0 0508 1 291 26 0 0159 0 4049 36 0 00500 0 127 7 0 1443 3 665 17 0 0453 1 150 27 0 0142 0 3606 37 0 00445 0 1131 8 0 1285 3 264 18 0 0403 1 024 28 0 0126 0 3211 38 0 00397 0 1007 9 0 1144 2 906 19 0 0359 0 9116 29 0 0113 0 2859 39 0 00353 0 08969 10 0 1019 2 588
160. oil Cal key The COIL CAL screen will appear on the display Enter the actual value of the field in the chosen units Press the Enter key to accept the change or the Escape key to cancel the entry and return the previous value The instrument will begin reading with the new coil parameter The sequence is successful if the display reading matches the value entered COIL SELECT AND PARAMETER STORAGE The Model 480 has non volatile internal memory available to store up to ten sets of coil parameters for user coils All coil parameters including input resistance and percent scale factor can be stored in each of the ten memory locations Unused parameters can be left at their default value Once the parameters are stored they can be called up quickly whenever coils are changed This feature can be used to store parameter values in a Model FCBL 6 accessory and percent scale factor into Lake Shore probes Parameters stored in probe memory are called up when the instrument is turned on Advanced Operation 5 7 5 6 1 5 6 2 5 6 3 Lake Shore Model 480 Fluxmeter User s Manual Storing New Coil Parameters into Instrument Memory Turn the instrument Off O and attach the new coil to the rear of the instrument Turn power On I Push the Coil Setup key and enter all relevant coil parameters as detailed in Paragraph 5 3 This accomplished press and hold the Coil Select key until you see the following display Se ect Wi th at Save Coi
161. oltage Offset locations 8 9 10 11 26 27 28 29 from the computer using the form CALZERO lt location gt lt reading gt 8 Send negative average reading to Range Voltage Offset locations 14 15 16 17 32 33 34 35 from the computer using the form CALZERO lt location gt lt reading gt Include the with the reading 8 9 5 AC RMS and AC Peak Gain Calibration The following procedure is to be repeated for each range entry in Table 8 1 Table 8 1 AC Calibration Table Range Input R Freq Amplitude Vs nom CalRng Vs pk Pk Rng Pk Rng 30 mV s 100 kQ 60 Hz 5 655 Vrms 15 mV s 20 21 2 mV s 26 32 3mV s 100kQ 60Hz 0 7540 Vrms 2mV s 21 2 83 mV s 27 33 300 uV s 100 kQ 1 kHz 1 257 Vrms 200 uV s 22 283 UV s 28 34 30 uV s 100kQ 1 kHz 0 1257 Vrms 20 uV s 23 n a n a n a 3mV s 10kQ 60 Hz 0 7540 Vrms 2mV s 2 2 83 mV s 8 14 300 uV s 10kQ 1kHz 1 257 Vrms 200 uV s 3 283 UV s 9 15 30 uV s 10kQ 1kHz 0 1257 Vrms 20 uV s 4 28 3 UV s 10 16 3uV s 10kQ 10 kHz 0 1257 Vrms 2 uV s 5 n a n a n a AC RMS Calibration 1 Connect Oscillator to Model 480 input terminals observe ground using the 1 uF series capacitor in series with the signal lead 2 Connect DVM in parallel with the Model 480 input terminals set to AC 3 Set Model 480 units to mV s 4 Set Model 480 to AC non peak operation 5 Set Model 480 range per Table 8 1 6 Set Model 480 input resistance p
162. olts momentarily a small voltage will rise a few seconds later across the capacitor Likewise a rapid charge of a capacitor to some voltage will be followed by a slight reduction of that potential occurring over several seconds This characteristic is usually referred to as Dielectric Absorption The effect of dielectric absorption in the Model 480 fluxmeter is a slight reading change over several seconds after a larger reading change This occurs predictably during reading changes from 0 to some level and more notably occurs when the reading is reset A reset from a large full scale reading will show a creeping up of the reading for several seconds after the reset The level of this effect is approximately 0 03 of the reading change The effect is most noticeable in the first few seconds and stabilizes after 20 30 seconds For the most accurate reset of larger measurements an initial reset should be followed by a second reset a few seconds later As inconvenient as this is capacitor limitations create this condition and cannot be easily remedied The capacitor selection for the Model 480 included testing of many vendors and capacitor dielectric types The selected capacitors offer the best overall characteristics including that of dielectric absorption It is felt that even though this is certainly a source of error for all analog integrating fluxmeters the Model 480 is capable of seeing this characteristic with it s increased resolution while
163. omparing values As an example assume a sorting criteria is given as 10 deviation from a standard magnet The standard magnet can be measured with the Model 480 lts measurement scaled to a 100 reading on the display Magnets measuring between 90 and 110 pass and others fail The percent scale factor is the coil parameter used to scale a percent measurement It is the only coil parameter that can be changed on a Lake Shore probe Before Using Set Percent The set percent feature can be used to calculate a percent scale factor The feature can be initiated with the instrument set to any measurement units but if the coil is uncalibrated it is recommended that the sequence be started with the units set to V s Several measurements of the test magnet should be made to assure repeatability An improper range setting or excess drift can cause difficulty in repeating measurements Set Percent Begin the set percent sequence by resetting the reading with the Reading Reset key or the peak hold value with the Peak Reset key Make a measurement of the sample magnet or place the coil in a known magnetic environment Press the Set Percent key The Enter Percentage screen will appear on the display Enter Percent ade 1 64 D z Use the keypad to enter the percent value that is to be assigned to the measurement often 100 but it can be different then press the Enter key The cursor will jump to a space before Use the a or v keys to s
164. on latching so the alarm state will change as soon as the alarm condition is removed To set alarm setpoints press the Alarm Setup key The first screen is as follows Enter Hi 9h Al arm 2 Sk 6 Use the numeric keypad to enter the high alarm setpoint magnitude only The cursor will jump to a space before the unit in this case G Use the a or v keys to select prefix u m _ k or M Press the Enter key The Enter Low Alarm screen then appears Enter Low Al arm 1 DD Use the numeric keypad to enter the low alarm setpoint magnitude only The cursor will jump to a space before the unit in this case G Use the a or v keys to select prefix u m _ k or M Press the Enter key The alarm mode can be set to inside or outside Outside is the more common alarm operating mode where a low alarm state is active when the measured value is below the low setpoint and a high alarm is active when the measured value is above the high setpoint When sorting permanent magnets in outside mode an active alarm indicates a failed part Inside mode reverses the operation of the audible alarm and annunciator An alarm is active when the measured value is between the alarm setpoints When sorting permanent magnets in inside mode an active alarm indicates a good part After the Enter Low Alarm display the next display is the Alarm In Out screen Se ect Wi th at Al arm I n gt
165. onicnocnnnoccconccnnnrn nana nan cnn rca narran 6 15 6 2 4 Troubleshooting iia apra iii 6 19 6 3 IEEE 488 SERIAL INTERFACE COMMAND GUMMADNY 6 20 6 3 1 Command List Structure gege ae Renee lene dE a EE EE Pas 6 21 6 3 2 IEEE 488 Serial Interface Commands Alphabetical Listing 0 cccceceeeeseeeeeeees 6 21 Table of Contents Lake Shore Model 480 Fluxmeter User s Manual TABLE OF CONTENTS Continued Chapter Paragraph Title Page 7 ACCESSORIES COILS AND PROBES J ccccsccsseesceeeeeenssnsseceeeeeensnnsneaeeeseseeasnncaeeeseeesasensscaeaesenneas 7 1 7 0 GENERAL eege cides Suse tase etl KEE 7 1 7 1 ACCESSORIES cana ade 7 1 7 2 FIELD MEASURING PROBE S cia Ute me Se 7 3 7 2 1 TOO ei EE Gre 7 3 7 2 2 tem FIGIG Probe fhe Sues Sage ick Gage eeh Dese Dee ee Ae 7 4 7 3 HELMHOLTZ e el 7 5 7 4 REFERENCE MAGNE TS a a a a a a a aa a r a a ariaa 7 7 Ale EE 8 1 8 0 GENERAL sete A A E AO ONEN 8 1 8 1 GENERAL MAINTENANCE PRECAU IONS s a nnneanonnnnnnnnnnnsnnnnnnnnsnssennnnnnnnnsrrirnnnnsessrnn 8 1 8 2 Bean e ME MN ele GET 8 1 8 2 1 Identification of Electrostatic Discharge Sensitive Components oooocinocccoccccconanonancnancconns 8 2 8 2 2 Handling Electrostatic Discharge Sensitive Components oooccccncccinocconcccconccnnnnnnnnn conan 8 2 8 3 LINE VOLTAGE SELECTION coacciones 8 2 8 4 FUSE REPEAGEMENT T ea e aeaaeae a aE e Taea Aaaa hee band 8 3 8 5 REAR PANEL CONNECTOR DEFINITIONS c oococcccccnnccononononocnncnccoccconncononcnn
166. or a list of status flags Example To enable status flags 0 3 4 and 6 send the command SRE 89 term 89 is the sum of the bit weighting for each bit Bit Bit Weighting Event Name 0 1 FDR 3 8 AAF 4 16 OVI 6 64 SRQ 89 xSRE Query the Configuration of Status Reports in the Service Request Enable Register Input SRE Returned lt SRE bit weighting gt Format nnn term Remarks The integer returned represents the sum of the bit weighting of the enabled bits in the Service Request Enable Register Refer to the STB command for a list of status flags 6 22 Computer Interface Operation STB Input Returned Remarks TST Input Returned Remarks WAI Input Returned Remarks ACDC Input Returned Remarks ACDC Input Returned Remarks ADDR Input Returned Remarks ADDR Input Returned Remarks Lake Shore Model 480 Fluxmeter User s Manual Query Status Byte STB lt STB bit weighting gt Format nnn term Acts like a serial poll but does not reset the register to all zeros The integer returned represents the sum of the bit weighting of the status flag bits that are set in the Status Byte Register Bit Bit Weighting Event Name Bit Bit Weighting Event Name 0 1 FDR 4 16 OVI 1 2 AAG 5 32 ESB 2 4 ALM 6 64 SRQ 3 8 AAF Query Self Test TST 0 or 1 Format n term The Model 480 performs a self test at power up 0 no errors found 1 errors found Wait t
167. ore Model 480 Fluxmeter User s Manual 5 3 2 Coil Resistance Coil resistance can often be ignored because it is usually small compared to the input resistance of the Model 480 If the DC resistance of the coil is more than 0 1 of the input resistance it can reduce measurement accuracy and should be entered as a coil parameter If it is less than that it can be ignored and set to the default value of 0 Q If an input resistance of 0 Q is selected a non zero coil resistance must be entered for the fluxmeter to make any measurements If the input and coil resistance are both set to zero the display value will blink To enter coil resistance continue from input resistance entry or press the Coil Setup key and press the Enter key until the Enter Coil R screen appears Enter Coil F 1 DER A Use the numeric keypad to enter the coil resistance then press the Enter key The cursor will jump to a space before the Q symbol Use the a or v keys to select prefix u m _ k or M Press the Enter key then the Escape key 5 3 3 Number of Turns N Number of turns in a coil is needed for the Model 480 to make magnetic measurements in flux units If the number of turns is set to the default of 1 flux measurement values will equal integrator measurement values To enter coil number of turns continue from coil resistance entry or press the Coil Setup key and press the Enter key until the Enter Turns screen appears Enter Tu
168. ors the logic level of this input which can then be read over computer interface The input is TTL compatible A logic low will produce a 0 interface response and a logic high will produce a 1 interface response The signal is internally pulled up to allow operation with a simple switch closure between Pins 14 and 13 3 4 Instrument Setup 4 0 4 1 4 2 Lake Shore Model 480 Fluxmeter User s Manual CHAPTER 4 BASIC OPERATION GENERAL This chapter provides basic operating instructions for the Lake Shore Model 480 Fluxmeter Turning on power is described in Paragraph 4 1 display definition in Paragraph 4 2 reading format in Paragraph 4 3 keypad definition in Paragraph 4 4 general keypad operation in Paragraph 4 5 and quick start procedures in Paragraph 4 6 TURNING ON POWER After line voltage verification Paragraph 3 3 plug the instrument end of the line cord included with the connector kit into the line cord input on the instrument rear Plug the other end of the line cord into a properly grounded three prong receptacle Turn the power switch located next to the line cord receptacle to ON I The instrument begins the power up sequence detailed as follows 1 The instrument alarm beeper beeps once 2 The display shows a message with the instrument model number 3 The display clears 4 The normal reading display appears An alarm annunciator beeper or overload OL indicator are not cause for immediate concern
169. otential A is displayed on the screen then press the Enter key A quick message that details which input parameters are necessary to perform calculations in the units you have selected will appear then disappear 5 Press the Coil Setup key For this procedure we will assume an Input Resistance of 100 kQ Press the a or v keys until Input R 100k is displayed on the screen press the Enter key then the Escape key 6 If the coil resistance is less than 100 or is unknown the default value of 0 Q is acceptable and you may skip this step Otherwise press the Coil Setup key Press the Enter key until Enter Coil R is displayed Use the numeric keypad to enter the coil resistance then press the Enter key The cursor will jump to a space before the Q symbol Use the a or v keys to select prefix for Q or k for KQ Press the Enter key then the Escape key 7 Press the Coil Setup key Press the Enter key until Potential Constant is displayed Use the numeric keypad to enter the Potential constant then press the Enter key The cursor will jump to a space before A Vs Use the a or v keys to select prefix _ Press the Enter key then the Escape key NOTE All the other settings Turns Area Turns etc are ignored when using potential units 8 Press the AC DC key until DC is displayed on the screen 9 Press the Peak Hold key until Peak Hold Off is displayed on the screen 10 Press the Range key Use
170. overview in Paragraph 2 6 2 1 INTEGRATING INSTRUMENTS 2 1 1 What Is An Integrator The output of the integrator in a fluxmeter is proportional to oc the voltage at its input as it varies with time In the most simple example a voltage of 1 volt V present at the input of a fluxmeter for 1 second s results in a reading of 1 volt second V s Volt seconds are the primary unit of measurement for an integrator The product of volts and seconds is the area under the voltage line if it were plotted on a graph against time When the input voltage changes in an irregular way integrator output cannot be calculated by simply multiplying voltage and time The integrator reacts continuously to the changing input to give an accurate area measurement Input Output V s Input V area 1 V Output V s area 1 time s time s C 480 2 1 eps 2 1 2 Why Integrators Are Used For Magnetic Measurement Integrators are used in magnetic measurements because of the physical relationship between coils of wire and magnetic flux The instantaneous voltage produced across a coil Neen is proportional to the number of turns in the coil N times the rate of change in flux d dt F nie cou dt It is inconvenient to use this relationship directly for DC measurements because the voltage disappears as soon as the flux stops changing The voltage is also proportional to the rate of change in flux and not the total change in flux
171. ow as magnetic potential magnetic units Units used in measuring magnetic quantities Includes ampere turn gauss gilbert line of force maxwell oersted and unit magnetic pole magnetization M This is a material specific property defined as the magnetic moment m per unit volume V M m V Measured in SI units as A m and in cgs units as emu cm 1 emu cm 10 A m Since the mass of a sample is generally much easier to determine than the volume magnetization is often alternately expressed as a mass magnetization defined as the moment per unit mass magnetostatic Pertaining to magnetic properties that do not depend upon the motion of magnetic fields mains See line voltage Maxwell Mx A cgs electromagnetic unit of magnetic flux equal to the magnetic flux which produces an electromotive force of 1 abvolt in a circuit of one turn link the flux as the flux is reduced to zero in 1 second at a uniform rate MKSA System of Units A system in which the basic units are the meter kilogram and second and the ampere is a derived unit defined by assigning the magnitude An x 107 to the rationalized magnetic constant sometimes called the permeability of space NBS National Bureau of Standards Now referred to as NIST National Institute of Standards and Technology NIST Government agency located in Gaithersburg Maryland and Boulder Colorado that defines measurement standards in the United States See Standards Laboratories for
172. ple point of water 273 16 K the equilibrium temperature that pure water reaches in the presence of ice and its own vapor line regulation The maximum steady state amount that the output voltage or current will change as the result of a specified change in input line voltage usually for a step change between 105 125 or 210 250 volts unless otherwise specified Glossary of Terminology A 3 Lake Shore Model 480 Fluxmeter User s Manual line of flux An imaginary line in a magnetic field of force whose tangent at any point gives the direction of the field at that point the lines are spaced so that the number through a unit area perpendicular to the field represents the intensity of the field Also know as a Maxwell in the cgs system of units line voltage The RMS voltage of the primary power source to an instrument load regulation A steady state decrease of the value of the specified variable resulting from a specified increase in load generally from no load to full load unless otherwise specified M Symbol for magnetization See magnetization magnetic air gap The air space or non magnetic portion of a magnetic circuit magnetic field strength H The magnetizing force generated by currents and magnetic poles For most applications the magnetic field strength can be thought of as the applied field generated for example by a superconducting magnet The magnetic field strength is not a property of materials Measure in SI units
173. possible 9 Set Model 480 for drift Auto Adjust and wait 30 seconds for the routine to complete 10 Verify an acceptable drift hold less than 2 uVs 11 Trigger one oscillator burst measure DC voltage to the Model 480 during the burst 8 12 Service and Calibration Lake Shore Model 480 Fluxmeter User s Manual DC and DC Peak Calibration Continued 8 9 7 8 9 7 1 12 Get actual Model 480 reading within 1 second of burst end 13 Calculate Ideal V s Burst period x DC voltage to Model 480 14 Calculate the Calibration Constant 1e 6 x Ideal V s Actual V s NOTE This value must be 1e 6 5 A value outside this tolerance indicates a major malfunction of the Model 480 that requires repair 15 Send Calibration Constant to the appropriate range location per Table 8 2 from the computer using the form CALGAIN lt location gt lt x xxxxxe x gt DC Peak Calibration 16 Set Model 480 to Dual Peak operation 17 Reset Model 480 wait 30 seconds reset Model 480 again 18 Trigger one oscillator burst measure DC voltage to Model 480 during the burst 19 Calculate Ideal V s Burst period x DC voltage to Model 480 20 Get actual Model 480 positive peak reading 21 Calculate the Calibration Constant 1e 6 x Ideal V s Actual V s NOTE This value must be 1e 6 5 A value outside this tolerance indicates a major malfunction of the Model 480 that requires repair 22 Send Calibration Constant to the appropriate pos
174. pplying the positive voltage under normal usage The green wire is at ground potential on the Model 480 If the polarity is not known just make the connection run a test and reverse the lead attachment if a different polarity reading is desired Caution The customer coil should be isolated from all line voltages or voltages referenced to earth ground f not damage to the Model 480 Fluxmeter is almost a certainty Once connections are made refer to Paragraph 5 6 2 for instructions for storing probe parameters in the internal EPROM TERMINAL BLOCK The Model 480 rear panel terminal block contains signals for alarms analog output and external reset The terminal block connectors are detachable Remove either the top or bottom terminal block from the instrument for convenient wire installation Up to 12 AWG stranded copper wire may be used though smaller wire is suitable for most applications CAUTION Always turn off the instrument before making any rear panel terminal block connections Terminal Description Terminal Description 1 High Alarm N O 9 Middle Alarm N O High Alarm COM 10 Middle Alarm COM High Alarm N C 11 Middle Alarm N C Low Alarm N O 12 External Reset Low Alarm COM 13 Ground for Ext Reset or Optional Input Low Alarm N C 14 Optional Input Monitor Output Signal 15 Corrected Output Signal Monitor Output Ground 16 Corrected Output Ground NI O71 BY Od Po
175. put voltage between the two values When Analog Mode User is selected you will see the Enter Max Output screen Enter Max Out PUT 1 D D mal le Use the numeric keypad to enter a high reading value that results in 10 V output then press the Enter key The cursor will jump to a space before the units Use the a or w keys to select prefix u m _ k or M Press the Enter key The Enter Min Output screen then appears Ent er Mi n Out Fut 14646 DDR Use the numeric keypad to enter a low reading value that results in 10 V output then press the Enter key The cursor will jump to a space before the units Use the a or w keys to select prefix u m _ k or M Press the Enter key Manual In manual mode the corrected output voltage can be set directly by the user The output is set in percent of full scale where 100 corresponds to 10 V and 100 corresponds to 10 V The setting resolution on the display is 0 001 but the actual resolution of the DAC is only 0 003 When Analog Mode Manual is selected you will see the Enter AOut Voltage screen Ent er AbDut Uol t age 1 D D z Use the numeric keypad to enter the percent of full scale that results in 10 V output then press the Enter key The cursor will jump to a space before the Use the a or w keys to select the _ prefix Press the Enter key Monitor Analog Output The monitor is a real
176. quest SRQ Bit 6 Determines whether the Model 480 reports via the SRQ line Six bits determine which status reports to make If bits 0 1 2 3 4 and or 5 are set then the corresponding bit in the Status Byte Register is set The Model 480 produces a service request only if bit 6 of the Service Request Enable Register is set If disabled the BUS CONTROLLER still examines Status Byte Register status reports by serial poll SPE but the Service Request cannot interrupt the BUS CONTROLLER The STB common command reads the Status Byte Register but will not clear the bits Computer Interface Operation 6 3 Lake Shore Model 480 Fluxmeter User s Manual Bus Control Commands Continued 6 1 3 2 Below are Status Byte Register bit assignments These reports occur only if enabled in the Service Request Enable Register Standard Event Status ESB Bit 5 When set indicates if one of the bits from the Standard Event Status Register has been set Refer to Paragraph 6 1 3 2 Overload Indicator OVI Bit 4 When set indicates a display overload condition Issues a Service Request if enabled Auto Adjust Fail AAF Bit 3 When set the Auto adjustment has failed This can occur if the drift rate of the instrument is greater than what can be adjusted for If this bit is set then the AAC bit will be set as well Alarm ALM Bit 2 When set an alarm condition exists This condition latches until acknowledged by the bus cont
177. r s Manual This Page Intentionally Left Blank vi Table of Contents 1 0 1 1 Lake Shore Model 480 Fluxmeter User s Manual CHAPTER 1 INTRODUCTION GENERAL This chapter provides introductory information for the Lake Shore Model 480 Fluxmeter Product description is in Paragraph 1 1 specifications in Paragraph 1 2 safety summary in Paragraph 1 3 and safety symbols in Paragraph 1 4 PRODUCT DESCRIPTION The Model 480 is a precision integrating fluxmeter that works with a variety of sensing coils to measure changing flux It is fundamentally an analog integrator under microprocessor control The analog integrator has excellent specifications and is very flexible lt performs well in a variety of magnet applications from a fast pulse to a slow ramp The microprocessor optimizes the performance of the integrator and enables numerous features and interfaces The Model 480 fits well into test and measurement operations from all manual to fully automated with quick setup and ease of use The fluxmeter complements the existing line of Lake Shore gaussmeters Manual Magnet Testing A bright display and fast reading update make the Model 480 ideal for manual magnet sorting and testing The low drift of the instrument improves productivity with fewer adjustments Remote terminals allow for foot pedal reading reset to keep hands on the work not the instrument Configurable alarms give an audible signal or relay closure to signify pass fail
178. ral gain ranges and a high speed peak hold Activating Peak Mode To turn peak mode On or Off press the Peak Hold key The screens below illustrate positive peak negative peak and both peaks 42 Irok G BC wol 3736 kG BC E FP S8 kG BC wl 8 36 kG NOTE The up caret or down caret next to the peak reading indicates positive or negative peak operation respectively 5 14 Advanced Operation 5 11 4 5 11 5 5 12 Lake Shore Model 480 Fluxmeter User s Manual Peak Reset In DC Peak mode the integrator peak hold hardware and peak hold software must all be reset before another reading can be made The peak reset function does all three from the front panel using the Peak Reset key over computer interface or with external reset The Reset Reading key still functions to reset the integrator only but its use is not recommended In AC Peak mode the peak hold hardware and peak hold software are reset using the Peak Reset key The integrator does not require reset The instrument is available for new readings 200 ms after the Peak Reset key is released if one peak value is being measured and 400 ms if both are being measured To reset peak press the Peak Reset key and release Choosing Positive Negative or Both Peaks Peak hold hardware in the Model 480 is capable of capturing both positive and negative peaks at the same time Either one or both of the v
179. ranty Some countries states or provinces do not allow limitations on an 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 disclaimed 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
180. raph 6 1 4 5 Type EXIT to quit the program 6 10 Computer Interface Operation Lake Shore Model 480 Fluxmeter User s Manual Faj National Instruments GPIBO Configuration GPIB PC2 2A Ver 2 1 Primary GPIB Address Secondary GPIB Address Timeout setting Select the primary GPIB adiress by using the left and right arrow leys This address is used to compute the talk and listen addresses which identify the board or device on the GPIB Valid primary addresses range from 0 to 30 00H to 1EH Terminate Read on EOS Set EOI with EOS on Vrites Type of compare on EG EOS byta NISSEN eet ce Send EOI at end of Write felding 32 to the primary address forms the Listen Address LA ding 64 to the primary address forms the Talk Address TA System Controller Assert REN when SC Enable Auto Serial Polling Enable CIC Protocol Bus Timing Parallel Poll Duration EXRPLE Selecting a primary address of 10 yields the following Use this GPIB board 10 32 42 Listen address Board Type PCIT 10 64 71 Talk address Base If 0 Address 02B 83h Fi Help F6 Peset Value F9 Esc Return to Map Ctl PqoJp PgIn Next Prev Board National Instruments DEVI Configuration GPIB PC2 2A Ver 2 1 Primary GPIB Address 312 Select the primery GPIB
181. re of a quantity for a periodic quantity the average is taken over one complete cycle Also known as effective value RS 232C Bi directional computer serial interface standard defined by the Electronic Industries Association EIA The interface is single ended and non addressable scalar A quantity which has magnitude only and no direction in contrast to a vector semiconducting material A conducting medium in which the conduction is by electrons and holes and whose temperature coefficient of resistivity is negative over some temperature range below the melting point semiconductor An electronic conductor with resistivity in the range between metals and insulators in which the electric charge carrier concentration increases with increasing temperature over some temperature range Note Certain semiconductors possess two types of carriers namely negative electrons and positive holes sensitivity The ratio of the response or change induced in the output to a stimulus or change in the input Temperature sensitivity of a resistance temperature detector is expressed as S dR dT setpoint The value selected to be maintained by an automatic controller 1 serial interface A computer interface where information is transferred one bit at a time rather than one byte character at a time as in a parallel interface RS 232C is a common serial interface SI Syst me International d Unit s See International System of Units stability The ability of
182. re this function Not all the coil parameters that appear sequentially after the Coil Setup key is pressed are needed for a coil Refer to Table 5 1 to determine which parameters are necessary for the measurement units being used Unknown parameter values should be left at default 5 2 Advanced Operation 5 3 1 Lake Shore Model 480 Fluxmeter User s Manual Input Resistance The analog integrator in the Model 480 will not function without an integrating resistance The integrating resistance is the sum of input resistance and coil resistance The input resistance parameter tells the Model 480 which input resistance to use inside the instrument There are three setting values available 100 kQ 10 kQ for normal measurements and 0 Q for special applications An input resistance of 100 kQ is the default setting and is appropriate for most applications The Model 480 achieves its best drift performance with this resistance An input resistance of 10 kQ is used when more sensitivity is required The full scale for each range setting drops by a factor of ten when input resistance changed from 100 kQ to 10 kQ The improved sensitivity may only be useful in the presence of very low drift The 0 Q input is used rarely when the coil resistance is very high and can act alone as the integrating resistance In these applications an input resistance inside the instrument would serve only to reduce sensitivity of the measurement Care must be taken when
183. re up to 31 C decreasing linearly to 50 at 40 C e Power supply voltage fluctuations not to exceed 10 of the nominal voltage e Overvoltage category Il e Pollution degree 2 Ground The Instrument To minimize shock hazard connect the instrument chassis and cabinet to an electrical ground The instrument is equipped with a three conductor AC power cable Plug the power cable into an approved three contact electrical outlet or use a three contact adapter with the grounding wire green firmly connected to an electrical ground safety ground at the power outlet The power jack and mating plug of the power cable meet Underwriters Laboratories UL and International Electrotechnical Commission IEC safety standards Ventilation The instrument has ventilation holes in its top and bottom covers Do not block these holes when the instrument is turned on 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 covers Refer component 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 sub
184. red to reduce the magnetic induction B ina magnetic material to zero from saturation The coercivity would be the upper limit to the coercive force compliance voltage See current source Curie temperature Tc Temperature at which a magnetized sample is completely demagnetized due to thermal agitation Named for Pierre Curie 1859 1906 a French chemist current source A type of power supply that supplies a constant current through a variable load resistance by automatically varying its compliance voltage A single specification given as compliance voltage means the output current is within specification when the compliance voltage is between zero and the specified voltage demagnetization when a sample is exposed to an applied field Ha poles are induced on the surface of the sample Some of the returned flux from these poles is inside of the sample This returned flux tends to decrease the net magnetic field strength internal to the sample yielding a true internal field Hint given by Hint Ha DM where M is the volume magnetization and D is the demagnetization factor D is dependent on the sample geometry and orientation with respect to the field deviation The difference between the actual value of a controlled variable and the desired value corresponding to the setpoint differential permeability The slope of a B versus H curve a dB dH differential susceptibility The slope of a M versus H curve ya dM dH digi
185. rement needs The inclusion of magnetic materials or special geometries can make a coil a specialized measurement tool Coil Sensitivity Sensitivity is the instantaneous voltage Veo produced for a given rate of change in flux dg dt As seen in the equation oc nie t V col the coil voltage is directly proportional to the number of turns N as well as the rate of change in flux Total change in flux can be measured as the fluxmeter integrates the instantaneous voltage over the measurement interval The following is an example of coil sensitivity related to a permanent magnet Consider a permanent magnet has a pole area A 1 cm and internal flux density B of 1000 G The flux i BA 1 000 Mx A typical coil of 100 turns N that fits snugly around the magnet pole generates an integrator output of 1000 Mx times 100 turns 105 MxN 1mV s as the magnet is moved into the coil A coil of more turns would give a larger output 2 6 Magnetic Measurement Overview Lake Shore Model 480 Fluxmeter User s Manual Coil Sensitivity Continued 2 2 2 2 2 3 Number of turns is important to coil design because it determines coil sensitivity Ideally increasing the number of turns always improves coil sensitivity but in the real world several factors limit the number of turns The most important are coil size DC resistance of the wire and peak output voltage It is possible for a coil to be too sensitive Coils should be
186. rns 1 DEI Turns Use the numeric keypad to enter the number of turns N of the coil then press the Enter key The cursor will jump to a space before the word Turns Use the a or v keys to select prefix u m _ K or M Press the Enter key then the Escape key 5 3 4 Area A The Model 480 must have an accurate area turns AN value for a coil in order to make flux density measurements This parameter can be entered in two ways The user can enter a separate turns value and area value in which case the instrument will calculate and store the area turns product The user can also enter a value for the area turns parameter directly by pressing the Enter key to skip over the area setting screen To enter coil area continue from coil turns entry or press the Coil Setup key and press the Enter key until the Enter Area screen appears Enter Area 1 BEID cm Use the numeric keypad to enter the area A of the coil in cm then press the Enter key The cursor will jump to a space before the cm Use the a or vw keys to select prefix u m _ K or M Press the Enter key then the Escape key 5 4 Advanced Operation 5 3 5 5 3 6 5 3 7 Lake Shore Model 480 Fluxmeter User s Manual Area Turns AN The Model 480 must have an accurate area turns AN value for a coil in order to make flux density measurements The user can also enter a value for the area turns parameter directly from the Enter Area Turns screen If a separate tu
187. rns value and area value are entered before this screen appears the calculated area turns product will be stored for this parameter The new value will not be calculated or displayed until the Coil Setup sequence is complete If a calculated value is desired continue past the setting screen if not enter the area turns value Area turns are entered in cm units which can be a source of confusion because the area parameter which is different uses the same units To enter coil area turns continue from coil area entry or press the Coil Setup key and press the Enter key until the Enter Area Turns screen appears Enter Area Turns 1 BBBBB _ cm Use the numeric keypad to enter the product of the area times the number of turns A N of the coil in cm then press the Enter key The cursor will jump to a space before the cm Use the a or v keys to select prefix 1 m _ K or M Press the Enter key then the Escape key Remember Enter either A and N or A N all three need not be entered Helmholtz Constant A Helmholtz constant of a Helmholtz coil is required for the Model 480 to make magnetic moment measurements The only available moment measurement unit is Wb cm which is a more convenient form of the more traditional Wb m The Helmholtz constant must be entered in cm for the display reading to have appropriate resolution For additional details refer to Paragraph 2 5 3 To enter Helmholtz constant continue from coil
188. roller Auto Adjust Complete AAC Bit 1 When set the Auto Drift adjustment has been completed This bit will be set even if the Auto Drift adjustment fails Refer to the AAF bit above Field Data Ready FDR Bit 0 When set new valid field readings are available Standard Event Status Register and Standard Event Status Enable Register The Standard Event Status Register supplies various conditions of the Model 480 STANDARD EVENT STATUS REGISTER FORMAT E ae E E EE A A ere Weighting 128 64 32 16 8 4 2 1 Bit Name Bits 2 and 6 are not used Reports of this register interrupt the user only if the bits are enabled in the Standard Event Status Enable Register and if bit 5 of the Service Request Enable Register is set The Standard Event Status Enable Register allows the user to enable any of the Standard Event Status Register reports The Standard Event Status Enable command ESE sets the Standard Event Status Enable Register bits Setting a bit of this register enables that function To set a bit send the command ESE with the sum of the bit weighting for each bit to be set Refer to the ESE command The Standard Event Status Enable Query ESE reads the Standard Event Status Enable Register ESR reads the Standard Event Status Register Once this register is read the bits reset to zero Power On PON Bit 7 Set to indicate a controller off on off transition Command Error CME Bi
189. ront Panel Display Brightness Input BRIGT lt bright gt Returned Nothing Remarks Sets the front panel display brightness 0 25 1 50 2 75 3 100 Default 2 BRIGT Query Front Panel Display Brightness Input BRIGT Returned 0 1 2 or 3 Format n term Remarks Queries the front panel display brightness 0 25 1 50 2 75 3 100 Default 2 CODE Set Front Panel Keyboard Lock Code Input CODE XXX Returned Nothing Remarks Sets front panel keyboard lock code Default 123 Enter any three numbers CODE Front Panel Keyboard Lock Code Query Input CODE Returned XXX Remarks Returns the 3 numbers that comprise the front panel keyboard lock code 6 26 Computer Interface Operation COILA Input Returned Remarks COILA Input Returned Remarks COILAN Input Returned Remarks COILAN Input Returned Remarks COILCAL Input Returned Remarks COILINR Input Returned Remarks COILINR Input Returned Remarks COILKH Input Returned Remarks Lake Shore Model 480 Fluxmeter User s Manual Set Coil Area COILA nnn nnnE tnn Nothing Sets coil area for current coil in units of cm Enter up to 6 digits and a decimal point in exponential form Query Coil Area COILA nnn nnnE nn Returns coil area for current coil in units of cm Returns up to 6 digits and a decimal point in exponential form Set Coil Area Turns COILAN nnn nnnE nn Nothin
190. s mode 5 22 Advanced Operation Lake Shore Model 480 Fluxmeter User s Manual Table 5 2 Default Values Command Function Interface Display Common Commands ESE Std Event Status Enable Report seeeeeeee OOO iodo Disabled SRE Service Request Enable Register Report O00 scsi Disabled Interface Commands ADDR Set IEEE 488 Address na 12 BAUD Set Serial Interface Baud Hate 0aeeeeenee See te E eas 9600 Baud END Set End Or Identify EOI Deet td EOI Enabled MODE Set Local Remote Mode Ds Local Mode TERM Set Terminating Character Type s s s Ona Bees ee lt CR gt lt LF gt Device Specific Commands ACDC Set AC DC Field Reading Mode Dad DC ALARM Set Alarm Function oooccoocccinoccconcccnonannnannnnncccnno Dia Off ALMB Set Audible Alarm Function ooooccccnnccinnccconccccn A ech ATT Off ALMH Set Alarm High Point 0 00000 0 00000 ALMIO Set Alarm Trigger In Out Mode A der Outside ALML Set Alarm Low Point 0 00000 0 00000 ANOCON Set Analog Out Control 0 00000 0 00000 ANOH Set Analog Out High Point 0 00000 0 00000 ANOL Set Analog Out Low Point 0 00000 0 00000 ANOM Set Analog Out Mode n Oea EN Default BRIGT Set Display Brightness cccceeeeeeeeneeees EE 75 CODE Set Keyboard Lock Code E E 123 COILA Set Coil Ares eeeccecececceeeeeseeeseeeeteeeeeeneeeeeneeees 1 00000 1 00000 cm COILAN
191. s or Terminator setting 6 1 2 IEEE 488 Command Structure The Model 480 supports several command types These commands are divided into three groups 1 Bus Control refer to Paragraph 6 1 2 1 a Universal 1 Uniline 2 Multiline b Addressed Bus Control 2 Common refer to Paragraph 6 1 2 2 3 Interface and Device Specific refer to Paragraph 6 1 2 3 6 1 2 1 Bus Control Commands A Universal Command addresses all devices on the bus Universal Commands include Uniline and Multiline Commands A Uniline Command Message asserts only a single signal line The Model 480 recognizes two of these messages from the BUS CONTROLLER Remote REN and Interface Clear IFC The Model 480 sends one Uniline Command Service Request SRQ REN Remote Puts the Model 480 into remote mode IFC Interface Clear Stops current operation on the bus SRQ Service Request Tells the bus controller that the Model 480 needs interface service A Multiline Command asserts a group of signal lines All devices equipped to implement such commands do so simultaneously upon command transmission These commands transmit with the Attention ATN line asserted low The Model 480 recognizes two Multiline commands LLO Local Lockout Prevents the use of instrument front panel controls DCL Device Clear Clears Model 480 interface activity and puts it into a bus idle state 6 2 Computer Interface Operation Lake Shore Model 480 Fluxmeter User s Manual
192. s then identified and it is shown how that rate of change is the only true limit on peak speed Finally coil sensitivity is discussed and examples are given of how to determine appropriate area turns of a coil The Magnetizer Pulse In many cases the magnetizer current is provided by a quick high current discharge of a capacitor bank The shape of the magnetic field during this discharge is shown in the figure below B Bp t P Mag_pulse bmp tp 2 4 Magnetic Measurement Overview Lake Shore Model 480 Fluxmeter User s Manual The Magnetizer Pulse Continued 2 1 7 2 2 1 7 3 2 1 7 4 The time tp to reach peak magnetic field Bp is considered the rise time of the pulse These are two important parameters to consider when selecting or designing the sense coil for the 480 Coil Output Voltage Limits Because of slew rate requirements and safety considerations the maximum voltage at the coil output should be limited to 60 volts The Model 480 Fluxmeter is capable of measuring the fastest of magnetizer pulses so long as the 60 volt limit is not exceeded Therefore the area turns of the coil must be matched to the peak field and rise time of the magnetic field pulse The equation for calculating the coil voltage in CGS units is dB Y NA x10 at where V volts A cm B gauss N number of coil turns and t seconds The equation for calculating the coil voltage in Sl units is dB Y NA
193. s three modes of operation default user and manual When the output is being setup the mode must be selected first Only parameters related to the selected mode will be shown on setting screens To set the corrected analog output mode press the Analog Out key to display the following screen Sel ect With 47 Anal o9 Mode Der aul t Use the A or Y keys to cycle through the mode selections described below When the cursor indicates the desired mode press the Enter key to accept it or the Escape key to exit the screen and revert to the previous mode Advanced Operation 5 19 Lake Shore Model 480 Fluxmeter User s Manual Corrected Analog Output Continued 5 15 2 Default In default mode the corrected analog output mimics the monitor output The output is scaled to Vs units no matter what units are selected for the display Full scale for the selected range is scaled to 3 V so for example on the 300 mV s range a 300 mV s reading would give a 3 V output and a 300 mV s reading would give a 3 V output The scale is changed automatically when range is changed User In user mode the user selects a value that corresponds to the maximum voltage output 10 V and a value that corresponds to the minimum voltage output 10 V In this mode the user can scale the analog output to improve resolution over an area of interest Maximum and minimum values are entered in the units selected for the display The instrument scales out
194. ss and hold to reset instrument to default values Up Arrow Chooses between parameter values during setting operations Down Arrow Chooses between parameter values during setting operations Enter Completes setting functions and returns to normal operation Press and hold to lock or unlock keypad GENERAL KEYPAD OPERATION There are three basic keypad operations 1 Direct Operation The key function occurs upon pressing the key Peak Reset Peak Hold Reading Reset AC DC Local and Alarm On Off operate directly when the key is pressed Setting Selection Users select from a list of settings Range Drift Adjust Units Coil Select Address Alarm Setup and Baud display setting options when pressed Use the up and down arrow keys as appropriate then press Enter to accept the change or Escape to return to the old selection Data Entry Users enter numeric data with the data entry keys Data entry keys include numbered keys the positive negative sign key and the decimal point key The Coil Setup Alarm Setup Coil Cal Set Percent and Analog Out keys use data entry Use the data entry keys to enter the number value then press the Enter key to accept the new data and advance to the prefix field Use the a or v keys to select the appropriate prefix and press the Enter key again to complete the operation Press the Escape key any time before the operation is complete to return to the old value Units prefixes of u m _
195. stance of the coil itself Enter up to 6 digits and a decimal point in exponential form 6 28 Computer Interface Operation COILR Input Returned Remarks COILSAVE Input Returned Remarks DACCRS Input Returned Remarks DACCRS Input Returned Remarks DACFINE Input Returned Remarks DACFINE Input Returned Remarks DCRES Input Returned Remarks DCRES Input Returned Remarks Lake Shore Model 480 Fluxmeter User s Manual Query Coil Resistance COILR nnn nnnE nn Returns coil resistance for current coil in units of ohms Q This is the DC resistance of the coil itself Returns up to 6 digits and a decimal point in exponential form Initiate Coil Save Command COILSAVE lt coil number gt Nothing Saves the current coil parameters to a coil location 1 10 internally stored coil parameters 11 probe data Any previous information in the coil location will be overwritten A probe with a PROM attachment Lake Shore Part Number FCBL 6 is required to write to probe data coil number 11 Set Coarse Drift Adjustment DAC Value DACCRS nnn nnnE nn Nothing Sets the percentage of full scale of the coarse drift adjustment DAC Enter up to 6 digits and a decimal point in exponential form Valid values are from 100 to 100 Query Coarse Drift Adjustment DAC Value DACCRS nnn nnnE tnn Returns the percentage of full scale of the coarse drift adjustment DA
196. stitute 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 exterior with a damp cloth and mild detergent SAFETY SYMBOLS Direct current power line Equipment protected throughout by double insulation or reinforced 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 Alternating current power line Alternating or direct current power line Three phase alternating current power line Earth ground terminal Caution or Warning See instrument documentation Background color Yellow Symbol and outline Black gt e p Protective conductor terminal Frame or chassis terminal On supply Off supply f Fuse O H A Introduction Lake Shore Model 480 Fluxmeter User s Manual CHAPTER 2 MAGNETIC MEASUREMENT OVERVIEW 2 0 GENERAL This chapter provides an overview of magnetic measurements relating to the operation of the Lake Shore Model 480 Fluxmeter Integrating instruments is in Paragraph 2 1 coil characteristics in Paragraph 2 2 flux overview in Paragraph 2 3 flux density overview in Paragraph 2 4 magnetic moment overview in Paragraph 2 5 and magnetic potential
197. t 1 thru 10 The smaller the percentage the smaller the change in reading that causes the filter to restart Refer to Paragraph 5 12 Query Display Filter Window FWIN lt window gt Format nn term Queries the display filter window lt window gt 1 thru 10 The smaller the percentage the smaller the change in reading that causes the filter to restart Refer to Paragraph 5 12 Query Keypad Status KEY 0 or 1 Format n term Queries if a key was pressed or power was cycled since the last KEY query 0 no key pressed 1 key pressed Configure Front Panel Keypad Lock Function LOCK lt off on gt Nothing Configures the front panel keypad lock function 0 Unlocked 1 Locked Computer Interface Operation Lake Shore Model 480 Fluxmeter User s Manual LOCK Query Front Panel Keypad Lock Function Input LOCK Returned 0 or 1 Format n term Remarks Queries the front panel keypad lock function 0 Unlocked 1 Locked MODE Configure Remote Interface Mode Input MODE lt mode gt Returned Nothing Remarks Configures the remote interface mode lt mode gt specifies which mode to operate 0 local 1 remote 2 remote with local lockout Press the front panel Local key to set the Model 480 to local provided the key has not been disabled by local lockout The Model 480 powers up in local mode MODE Query Remote Interface Mode Input MODE Returned lt mode gt Format n term
198. t 5 Set to indicate a command error since the last reading Controller unable to interpret a command due to syntax error unrecognized header or terminators or unsupported command Execution Error EXE Bit 4 Set to indicate an execution error This occurs when the controller is instructed to do something not within its capabilities Device Dependent Error DDE Bit 3 Set to indicate a device dependent error Determine the actual device dependent error by executing the various device dependent queries Query Error QYE Bit 2 Set to indicate a query error Occurs rarely but involves data loss due to full output queue Operation Complete OPC Bit 0 This bit is generated in response to the OPC common command It indicates when the Model 480 has completed all selected pending operations 6 4 Computer Interface Operation Lake Shore Model 480 Fluxmeter User s Manual 6 1 4 IEEE Interface Example Programs Two BASIC programs are included to illustrate the IEEE 488 communication functions of the instrument The first program was written in Visual Basic Refer to Paragraph 6 1 4 1 for instructions on how to setup the program The Visual Basic code is provided in Table 6 2 The second program is written in Quick Basic Refer to Paragraph 6 1 4 3 for instructions on how to setup the program The Quick Basic code is provided in Table 6 3 Finally a description of operation common to both programs is provided in Para
199. t across the outer two conductors The center conductor is a safety ground and connects to the instrument metal chassis For safety plug the cord into a properly grounded three pronged receptacle Power Switch The power switch turns the instrument On and Off and is located in the line input assembly on the instrument rear When Iis raised the instrument is On When O is raised the instrument is Off 3 2 Instrument Setup 3 4 3 5 3 5 1 Lake Shore Model 480 Fluxmeter User s Manual Line Cord Power On Off Fuse Input Switch Drawer H 100 120 220 240 V gt _10 6 Voltage 100 120V 0 25 A T 250V_0 25x1 25 50 60 Hz 40 VA MAX 220 240V 0 200 A T 250V 5x20mm F 480 3 2 eps Figure 3 2 Line Input Assembly COIL INPUT CONNECTION WARNING Many coils used with the fluxmeter have conductive parts Never probe near exposed live voltage Personal injury and damage to the instrument may result CAUTION Always turn off the instrument before making any rear panel Coil Input connections Connect sensing coils directly to the Model 480 rear panel binding posts The binding posts accept bare lead wires or a dual banana plug Ensure that connections are tight Loose wires can create unpredictable measurements Turn the instrument off before attaching coil wires See Figure 8 2 for pin definitions After connecting the coil refer to Paragraph 5 4 to enter the coil parameters into the instrument PROBE INPUT CONNECT
200. tal controller A feedback control system where the feedback device sensor and control actuator heater are joined by a digital processor In Lake Shore controllers the heater output is maintained as a variable DC current source digital data Pertaining to data in the form of digits or interval quantities Contrast with analog data dimensionless sensitivity Sensitivity of a physical quantity to a stimulus expressed in dimensionless terms The dimensionless temperature sensitivity of a resistance temperature sensor is expressed as Sa T R dR dT which is also equal to the slope of R versus T on a log log plot that is Sa d InR d InT Note that the absolute temperature in kelvin must be used in these expressions drift instrument An undesired but relatively slow change in output over a period of time with a fixed reference input Note Drift is usually expressed in percent of the maximum rated value of the variable being measured dynamic data exchange DDE A method of interprocess communication which passes data between processes and synchronized events DDE uses shared memory to exchange data between applications and a protocol to synchronize the passing of data dynamic link library DLL A module that contains code data and Windows resources that multiple Windows programs can access electromagnet A device in which a magnetic field is generated as the result of electrical current passing through a helical conducting coil It c
201. ter User s Manual 4 6 3 DC Flux Density Measurement In Units of G or T Use the following procedure to take a flux density measurement 1 Ensure power is turned Off O CAUTION Always turn off power to the Fluxmeter before making any rear panel PROBE INPUT or COIL INPUT connections 2 Attach the probe or coil to rear of the Fluxmeter Refer to Paragraph 3 4 for COIL INPUT and Paragraph 3 5 for PROBE INPUT connection instructions Turn power On I Press the Units key For this procedure we will use gauss G Press the a or v keys until Flux Density G is displayed on the screen then press the Enter key A quick message that details which input parameters are necessary to perform calculations in the units you have selected will appear then disappear 5 Press the Coil Setup key For this procedure we will assume an Input Resistance of 100 kQ Press the a or v keys until Input R 100k is displayed on the screen press the Enter key then the Escape key 6 If the coil resistance is less than 100 or is unknown the default value of 0 Q is acceptable and you may skip this step Otherwise press the Coil Setup key Press the Enter key until Enter Coil R is displayed Use the numeric keypad to enter the coil resistance then press the Enter key The cursor will jump to a space before the Q symbol Use the a or v keys to select prefix _ for Q or k for kQ Press the Enter key then the Escape key 7 Press t
202. testing or any other application where field changes are only present for a short time Drift is the dominant error seen in DC mode often limiting range and repeatability Drift compensation and integrator resets are always necessary when making DC measurements For best performance leave DriftTrak on whenever possible To select DC mode press the AC DC key DC operation is indicated by the letters Dc on the normal display to the right of the units indicator 5 12 Advanced Operation Lake Shore Model 480 Fluxmeter User s Manual 5 10 2 AC Measurement Mode AC mode is a natural extension of the measurement capabilities of an integrating DC fluxmeter With the selection of only a few different parts the Model 480 is made ready to measure periodic AC fields These fields may be present as stray field around transformers or leakage from switching power supplies AC mode measures in RMS and only the AC part of the field change is represented in the reading value the steady state DC field is ignored Peak hold can be used with AC mode to measure the peak value of periodic fields or to capture fast transients as described in Paragraph 5 11 AC measurements do not require drift compensation or integrator reset because modifications to the integrator bring the reading to zero when no signal is present Frequency response and noise dominate the error present in AC mode The Model 480 has a predictable frequency response which is illustrated in Figure 5
203. the a or v keys to cycle thru the available ranges Press the Enter key to accept or press the Escape key to cancel and return to the normal display READING RESET The analog integrator in the Model 480 must be reset to zero at the beginning of a DC measurement sequence Resetting the integrator removes any flux change or integrator drift that has accumulated since the last reset The DriftTrak algorithm Paragraph 5 9 3 can greatly reduce the number of resets needed for DC measurements AC and AC Peak measurements do not require reading reset because modifications to the integrator bring the reading to zero when no signal is present DC Peak measurements require peak reset Paragraph 5 11 4 instead of reading reset The integrator in the Model 480 is designed to recover quickly from a reading reset A new reading is available 200 ms after the Reading Reset key is released Reading reset can also be achieved through computer interface or using the external reset feature Paragraph 5 16 If the Model 480 appears to have more drift just after a reset than it does 10 to 30 seconds later it could be a result of dielectric absorption Paragraph 2 1 5 If the resulting error in reading is too large for the measurement application the error can be reduced by resetting a second time a few seconds after the first reset To reset the reading press the Reading Reset key and release Advanced Operation 5 9 5 9 5 9 1 Lake Shore Mode
204. tile memory in the connector Users need only plug in the connector turn the power on and begin taking measurements Magnetic Measurement Overview 2 9 2 3 2 4 2 4 1 Lake Shore Model 480 Fluxmeter User s Manual FLUX OVERVIEW Scientists envision a magnetic field as lines of flux leaving the north pole of a magnet and returning to the south pole The symbol for flux is q A unit of flux is called a line In the CGS system one line of flux equals one maxwell Mx In the SI system the flux unit is the weber Wb where 1Wb 10 Mx 10 lines Flux is the basic Model 480 magnetic measurement All other measurements derive from flux measurement and knowledge of the coil geometry Flux Lines C 480 2 5 eps Flux is measured to indicate energy transferred by a magnet or the energy capacity of a permanent magnet to sort magnets or to determine other magnetic properties such as flux density Paragraph 2 4 The most common way to measure flux is with a coil and integrating fluxmeter Knowing only the number of turns in the coil the fluxmeter measures flux as it changes Changing flux generates a voltage in the coil The coil voltage is integrated by the fluxmeter to show the total change in flux FLUX DENSITY OVERVIEW What is Flux Density A magnetic field consists of flux lines Flux density is the number of flux lines passing perpendicular through a plane of unit area A The symbol for flux density is B where B p
205. time analog voltage proportional to the integrator output The wave shape exactly duplicates that of the integrator output The scale of the monitor output is 3 V for the full scale volt seconds of the range selected The monitor output remains scaled to V s even when other units are displayed The monitor output is not as accurate as the corrected output because instrument and coil calibrations are digitally processed and do not act on the monitor voltage There is no user control of the monitor output The output is short protected but should never be used to drive a resistance of less than 1 KQ for specified accuracy Analog output terminals are in the detachable terminal block on the rear of the instrument 5 20 Advanced Operation 5 16 5 17 5 18 Lake Shore Model 480 Fluxmeter User s Manual EXTERNAL RESET The Model 480 terminal block has connections for external reset With this feature a foot pedal or Programmable Logic Controller PLC can be used to start a new measurement cycle The External Reset is TTL compatible and a logic low will activate a reset The signal is internally pulled up to allow operation with a simple switch closure between Pins 12 and 13 The external reset acts like a reading reset in DC mode and a peak reset in DC Peak and AC Peak mode Short the reset line or take it to logic low for at least 1 ms and then open it Reset completes 200 ms after the reset line is shorted or 400 ms for Dual Peak OPTIO
206. tions f improper site preparation or site maintenance g natural disasters such 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 holders 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 merchantability and fitness for a particular purpose Specifically except as provided herein Lake Shore undertakes no responsibility that the products will be fit for any particular purpose 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 limited war
207. to perform flux density measurements in units of gauss G or tesla T B Symbol for magnetic flux density See Magnetic Flux Density baud A unit of signaling speed equal to the number of discrete conditions or signal events per second or the reciprocal of the time of the shortest signal element in a character bit A contraction of the term binary digit a unit of information represented by either a zero or a one Glossary of Terminology A 1 Lake Shore Model 480 Fluxmeter User s Manual calibration To determine by measurement or comparison with a standard the correct accurate value of each scale reading on a meter or other device or the correct value for each setting of a control knob cathode The terminal from which forward current flows to the external circuit Anode Pel cathode Celsius C Scale A temperature scale that registers the freezing point of water as O C and the boiling point as 100 C under normal atmospheric pressure Celsius degrees are purely derived units calculated from the Kelvin Thermodynamic Scale Formerly known as centigrade See Temperature for conversions cgs system of units A system in which the basic units are the centimeter gram and second coercive force coercive field The magnetic field strength H required to reduce the magnetic induction B in a magnetic material to zero coercivity generally used to designate the magnetic field strength H requi
208. unctioned continually DISPLAY RESOLUTION The DC Mode display resolution or number of digits shown on the display can be changed between 5 and 4 digits The parameter does not change DC Peak AC or AC Peak resolution To change the display resolution press and hold the Filter key for 5 seconds The following screen is displayed Sel ect Wi th aF D Res 3 3 4 D1 gi ts Use the A or Y keys to select 5 or 4 digits Press the Enter key to accept it or the Escape key to retain the old setting and return to the normal display ALARM AND RELAY OPERATION The alarm feature on the Model 480 has enough flexibility to support several Pass Fail configurations in addition to simple fault detection A display annunciator and audible beeper signal an active alarm at the instrument Alarm states can be assigned to up to three relays for external monitoring or automated control If both peak readings are displayed the alarms follow the positive peak 5 16 Advanced Operation Lake Shore Model 480 Fluxmeter User s Manual 5 14 1 Alarm Setup There are four parameters associated with alarm setup The high and low setpoints are the alarm boundaries In general if the measurement value crosses a boundary an alarm state will change The setpoints are entered in the units selected for the display They are entered as magnitude only and are active for both positive and negative measurement values as shown in Figure 5 2 The alarms are n
209. und for Ext Reset or Optional Input Optional Input Corrected Output Signal Corrected Output Ground C 480 8 4 eps OO OO Joo ob F 480 8 5 eps Model 480 Fluxmeter Computers and Printers DB 25P L mee E Description Pin Description Pin Description No Connection Receive Data RD in Transmit Data TD out Data Terminal Ready DTR out Ground GND e Denn s GND 6 DataSetReady DSRin 7 op Let SR in Data Terminal Ready DTR out tied to 4 8 DCD in 7 RTS out 8 NoConnection Lal pop 8 CTS m 9 No Connection 22 Gsm 9 Ring in in Figure 8 5 SERIAL UO Connector Details Service and Calibration 8 5 Lake Shore Model 480 Fluxmeter User s Manual 8 5 1 Serial Interface Cable Wiring The following are suggested cable wiring diagrams for connecting the Model 480 Serial Interface to various Customer Personal Computers PCs Model 480 to PC Serial Interface PC with DE 9P Model 480 DE 9P Standard Null Modem Cable DE 9S to DE 9S PC DE 9P 5 GND AAA 5 GND 2 RD in AA K K K K K gt 3 TD out 3 TD out OD RD in 4 DTR out OOOO 6 DSR in 6 DSR in 4 DIR out 1 NC I 7 RTS out 7 DTR tied to 4 Sei gt 8 CTS in 8 NC 1 DCD in Model 480 to PC Serial Interface PC with DB 25P Model 480 DE 9P Standard Null Modem Cable DE 9S to DB 25S PC DB 25P 5
210. unlocks The lock code can be changed using either the IEEE 488 or RS 232C Computer Interface If the instrument is reset Paragraph 5 19 the lock code reverts to 123 The instrument cannot reset with the keypad locked Advanced Operation 5 21 Lake Shore Model 480 Fluxmeter User s Manual 5 19 RESETTING TO DEFAULT VALUES To reset all instrument parameters to default values press and hold the Escape key for 10 seconds Table 5 2 lists default values for each parameter Parameters stored in probes are not reset When you press and hold the Escape key for 10 seconds you see the following screen Code dat el EL dEr Der aul t Wal ues Ho Use the A or Y keys to select Yes or No Yes means you wish to reset the instrument to the default settings detailed in Table 5 2 No means you do not wish to reset the instrument When the display indicates the desired selection press the Enter key to accept it or the Escape key to exit the screen and revert to the previous mode If you select the Enter key you see the following screen Code date 027 26799 Cl ear Coi l s Ho Use the A or W keys to select Yes or No Yes means you wish to delete the User stored coil parameters No means you do not wish to delete the coil parameters When the display indicates the desired selection press the Enter key to accept it or the Escape key to exit the screen and revert to the previou
211. using the 0 Q range Without a large input resistance the input is more vulnerable to electrostatic discharge ESD and other voltage spikes A non zero coil resistance must be entered for the Model 480 to calculate a display value at all Because of the potential for problems the 0 setting can only be entered with a press and hold operation and if the coil resistance is zero the display value will blink To select an input resistance press the Coil Setup key You will see the following display Sel ect Wi th at Input Ri 1 Bik it Use the A or Y keys to select between 100 kQ and 10 KQ Press the Enter key to accept the change or the Escape key to cancel the entry and return the previous value The next screen in the coil setup will appear That parameter can be entered if needed or press the Enter key to continue past it or press the Escape key to return to the normal display To select an input resistance of 0 Q press and hold the Coil Setup key for 5 seconds Se ect Wi th at AN 1nrut Ho The 0 setting screen will appear Use the A or W keys to select Yes or No Press the Enter key to accept the change or the Escape key to cancel the entry and return the previous value The next screen in the coil setup function will appear That parameter can be entered if needed or press the Enter key to continue past it or press the Escape key to return to the normal display Advanced Operation 5 3 Lake Sh
212. ve peak range location per Table 8 1 from the computer using the form CALGAIN lt location gt lt x xxxxxe x gt Repeat Steps 4 thru 21 for next range of Table 8 1 until all AC ranges are calibrated 8 9 6 DC and DC Peak Calibration The following procedure is to be repeated for each range entry in Table 8 2 Table 8 2 DC Calibration Table Range Input R Freq Period Amplitude Offset Vs nom Cal Rng Pk Rng Pk Rng 300 mV s 100 kQ 0 1 Hz 5 sec 5 volts p p 2 5 volts 250 mV s 18 24 30 30 mV s 100 kQ 1 Hz 0 5sec 5 volts p p 2 5 volts 25 mV s 19 25 31 30mV s 10kQ 1 Hz 0 5sec 5 volts p p 2 5 volts 25 mV s 0 6 12 3mV s 10kQ 10Hz 0 05sec 5 volts p p 2 5 volts 2 5 mV s 1 7 13 DC Calibration 1 Install 100 1 resistive attenuator between oscillator and Model 480 input terminals 2 Connect DVM in parallel with the Model 480 input terminals set to DC 3 Set Model 480 units to V s 4 Set Model 480 to DC non peak operation 5 Set Model 480 range per Table 8 2 6 Set Model 480 input resistance per Table 8 2 7 Set Oscillator to the testing amplitude offset and frequency per Table 8 2 square wave burst mode NOTE Table 8 2 amplitudes are at the oscillator output DVM measured levels will be attenuated by 100 1 8 Measure the DC voltage to the Model 480 input and adjust the oscillator offset to make it as near 0 volts as
213. ving a device or assembly from a container must maintain contact with a conductive portion of the container Use only plastic bags approved for storage of ESD material 6 Do not handle ESDS devices unnecessarily or remove from the packages until actually used or tested LINE VOLTAGE SELECTION Use the following procedure to change the instrument line voltage selector Verify the fuse value whenever line voltage is changed WARNING To avoid potentially lethal shocks turn off controller and disconnect it from AC power before performing these procedures Identify the line input assembly on the instrument rear panel See Figure 8 1 Turn the line power switch OFF O Remove the instrument power cord With a small screwdriver release the drawer holding the line voltage selector and fuse Slide out the removable plastic fuse holder from the drawer Rotate the fuse holder until the proper voltage indicator shows through the window Verify the proper fuse value Re assemble the line input assembly in the reverse order 9 Verify the voltage indicator in the window of the line input assembly 10 Connect the instrument power cord e WEE a GO Ne oe 11 Turn the line power switch On I 8 2 Service and Calibration Lake Shore Model 480 Fluxmeter User s Manual Power On Off Screwdriver Fuse Switch Slt Drawer F 480 8 1 eps Figure 8 1 Power Fuse Access 8 4 FUSE REPLACEMENT Below is the procedure to remove and repla
214. ween these points is equal to one watt volt ampere VA The SI unit of apparent power The volt ampere is the apparent power at the points of entry of a single phase two wire system when the product of the RMS value in amperes of the current by the RMS value in volts of the voltage is equal to one volt second v s A voltage of 1 volt V present at the input of a fluxmeter for 1 second s results in a reading of 1 volt second v s Volt seconds are the primary unit of measurement for an integrator See Weber watt W The SI unit of power The watt is the power required to do work at the rate of 1 joule per second weber Wb The unit of magnetic flux in the mks system equal to the magnetic flux which linking a circuit of one turn produces in it an electromotive force of 1 volt as it is reduced to zero at a uniform rate in 1 second References 1 Sybil P Parker Editor Dictionary of Scientific and Technical Terms Fifth Edition New York McGraw Hill 1994 IBSN 0 07 042333 4 2 Christopher J Booth Editor The New IEEE Standard Dictionary of Electrical and Electronic Terms IEEE Std 100 1992 Fifth Edition New York Institute of Electrical and Electronics Engineers 1993 IBSN 1 55937 240 0 Definitions printed with permission of the IEEE 3 Nelson Robert A Guide For Metric Practice Page BG7 8 Physics Today Eleventh Annual Buyer s Guide August 1994 ISSN 0031 9228 coden PHTOAD A 6 Glossary of Terminology La
215. which is often the desired measurement If Veo is integrated to look at the area under Veo plotted against time the above problems disappear The integrator output is proportional to the total change in flux and rate of change does not matter Expressed mathematically Vout eNO 9 lr Magnetic Measurement Overview 2 1 Lake Shore Model 480 Fluxmeter User s Manual Why Integrators Are Used For Magnetic Measurement Continued The total flux change can be measured with a fluxmeter as a coil moves near a magnet or as a magnet moves near a coil DM T no DE Integrator D gt nput Vo Vout I V col ou I V s t 0 1 time s time s C 480 2 2 eps Important Integrator Characteristics Some parameters that describe the integrator in a fluxmeter are familiar like range and resolution If the measurement range is too small an over range condition can exist If the range is too large there is not enough resolution to make accurate measurements Available integrator ranges should be taken into account when designing sensing coils Ranges are often expressed in volt seconds which is the fundamental measurement of the integrator Range can be expressed in flux units if the number of coil turns is known Some characteristics of integrators are not seen in other measurements Two components dominate the behavior of an integrator its input resistance Rin and integrating capacitor Cint The expression for a voltage integr
216. y little effect on DC mode operation The peak hold circuit captures and holds the highest and lowest value present in the DC signal path since the last peak reset The circuit is many times faster than the instrument update rate and can capture an hold signals that cannot otherwise be seen on the display The peak hold circuit was designed to keep up with the fastest magnetizing pulses Drift is as much a problem in DC Peak mode as DC mode Drift compensation and integrator resets are necessary when making DC Peak measurements DriftTrak does not attempt to correct drift during DC Peak operation Peak Hold in AC Mode During AC mode operation the peak hold feature bypasses the RMS converter The peak amplitude of a periodic wave form is believed to be more useful than the maximum RMS value The highest and lowest peak AC values not RMS values present in the AC signal path are captured and held This distinction can cause some confusion For a sinusoidal wave form the peak value is approximately 1 4 times higher than the RMS For non sinusoidal wave forms the difference can be much larger AC Peak mode uses the same fast peak hold circuit as DC Peak mode enabling operation over a wide frequency range for periodic signals No drift compensation is required for AC Peak operation Non periodic field changes can also be captured using AC Peak mode There are several possible applications including magnetizers for a drift free integrator with seve
217. y of Terminology Lake Shore Model 480 Fluxmeter User s Manual general purpose interface bus GPIB Another term for the IEEE 488 bus gilbert Gb A cgs electromagnetic unit of the magnetomotive force required to produce one maxwell of magnetic flux in a magnetic circuit of unit reluctance One gilbert is equal to 10 41 ampere turn Named for William Gilbert 1540 1603 an English physicist hypothesized that the earth is a magnet gilbert per centimeter Practical cgs unit of magnet intensity Gilberts per cm are the same as oersteds Greek alphabet The Greek alphabet is defined as follows Alpha a A lota 1 I Rho p P Beta B B Kappa K K Sigma o z Gamma Y T Lambda A Tau T T Delta 5 A Mu u M Upsilon v Y Epsilon E E Nu v N Phi A p Zeta G Z Xi E Chi H X Eta n H Omicron o O Psi y Y Theta 0 O Pi T Tr Omega m Q ground A conducting connection whether intentional or accidental by which an electric circuit or equipment is connected to the earth or to some conducting body of large extent that serves in place of the earth Note It is used for establishing and maintaining the potential of the earth or of the conducting body or approximately that potential on conductors connected to it and for conducting ground current to and from the earth or of the conducting body H Symbol for magnetic field strength See Magnetic Field Strength Hall effect The generation of an electric potential perpendicular to both an electric current flowin

Model 480 - Lake Shore Cryotronics, Inc.

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