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Lake Shore 480 User Manual

Fluxmeter
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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: 2.2
User's Manual
Model 480
Fluxmeter
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
P/N 119-028
25 July 2017

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  • Page 1 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.
  • Page 2 Lake Shore receives notice of 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.
  • Page 3 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.
  • Page 4 Lake Shore Model 480 Fluxmeter User’s Manual EU DECLARATION OF CONFORMITY This declaration of conformity is issued under the sole responsibility of the manufacturer. Manufacturer: Lake Shore Cryotronics, Inc. 575 McCorkle Boulevard Westerville, OH 43082 Object of the declaration: Model(s):...
  • Page 5 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...
  • Page 6 Lake Shore Model 480 Fluxmeter User’s Manual This Page Intentionally Left Blank...

  • Page 7: Table Of Contents

    2.5.1 What is Magnetic Moment? ................... 2-11 2.5.2 Important Parameters of a Hemholtz Coil ..............2-11 2.5.3 Hemholtz Coil Constant Determination (For Non-Lake Shore Coils) ......2-12 MAGNETIC POTENTIAL OVERVIEW ................2-13 2.6.1 What is Magnetic Potential? ..................2-13 2.6.2 Important Parameters of a Potential Coil ...............
  • Page 8 Lake Shore Model 480 Fluxmeter User’s Manual TABLE OF CONTENTS (Continued) Chapter/Paragraph Title Page 3.3.2 Power Cord ........................3-2 3.3.3 Power Switch ........................3-2 COIL INPUT CONNECTION ....................3-3 PROBE INPUT CONNECTION ................... 3-3 3.5.1 Attachment To A Non-Lake Shore Coil ................3-3 TERMINAL BLOCK ......................
  • Page 9 Lake Shore Model 480 Fluxmeter User’s Manual TABLE OF CONTENTS (Continued) Chapter/Paragraph Title Page RANGE SELECTION ......................5-9 READING RESET ....................... 5-9 DRIFT ADJUSTMENT ...................... 5-10 5.9.1 Automatic Drift Adjustment .................... 5-10 5.9.2 Manual Drift Adjustment ....................5-11 5.9.3 DriftTrak™ ........................5-11 5.10...
  • Page 10 Lake Shore Model 480 Fluxmeter User’s Manual TABLE OF CONTENTS (Continued) Chapter/Paragraph Title Page ACCESSORIES, COILS, AND PROBES ....................7-1 GENERAL ..........................7-1 ACCESSORIES ........................7-1 FIELD MEASURING PROBES .................... 7-3 7.2.1 100 cm Field Probe ......................7-3 7.2.2 30 cm Field Probe ......................
  • Page 11 Lake Shore Model 480 Fluxmeter User’s Manual LIST OF ILLUSTRATIONS Figure No. Title Page Model 480 Rear Panel ........................3-2 Line Input Assembly ......................... 3-3 Model 480 Normal Display Definition ....................4-1 Model 480 Front Panel ........................4-2 Model 480 AC Frequency Response ..................... 5-13 Examples of Alarm Activation Inside and Outside High and Low Setpoints ........
  • Page 12 Lake Shore Model 480 Fluxmeter User’s Manual This Page Intentionally Left Blank Table of Contents...

  • Page 13: Introduction

    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.

  • Page 14: Specifications

    Lake Shore Model 480 Fluxmeter User’s Manual SPECIFICATIONS Measurement Number of Inputs: 1 Input Type: Two-lead, ground referenced Input Resistance: 100 k or 10 k 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.
  • Page 15 Helmholtz Coil (2.5 inch I.D.) FH-6 Helmholtz Coil (6 inch I.D.) FH-12 Helmholtz Coil (12 inch I.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...

  • Page 16: Safety Summary

    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.

  • Page 17: Magnetic Measurement Overview

    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 overview in Paragraph 2.6.

  • Page 18: Important Integrator Characteristics

    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.

  • Page 19: Reducing Integrator Drift

    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.

  • Page 20: Analog Versus Digital Integrators

    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.
  • Page 21 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.

  • Page 22: Making Ac Measurements

    Lake Shore Model 480 Fluxmeter User’s Manual 2.1.8 Making AC Measurements Traditionally, integrating fluxmeters make DC flux measurements where the measured field changes in 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.

  • Page 23: Coil Size

    Lake Shore Model 480 Fluxmeter User’s Manual Coil Sensitivity (Continued) 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.

  • Page 24: Coil Temperature Coefficient

    Lake Shore Model 480 Fluxmeter User’s Manual Coil Resistance (Continued) 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: Manufacturers specify integrator resistance for a fluxmeter typically between 1 k...

  • Page 25: Field Uniformity

    2.2.9 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.

  • Page 26: Flux Overview

    The symbol for flux is . 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: Flux is the basic Model 480 magnetic measurement. All other measurements derive from flux measurement and knowledge of the coil geometry.

  • Page 27: How Flux Density (B) Differs From Magnetic Field Strength (H)

    Lake Shore Model 480 Fluxmeter User’s Manual 2.4.2 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 measured in oersteds (Oe).

  • Page 28: Hemholtz Coil Constant Determination (For Non-Lake Shore Coils)

    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 per current unit) rather than the coil constant needed.

  • Page 29: Magnetic Potential Overview

    Lake Shore Model 480 Fluxmeter User’s Manual MAGNETIC POTENTIAL OVERVIEW 2.6.1 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.
  • Page 30 Lake Shore Model 480 Fluxmeter User’s Manual This Page Intentionally Left Blank 2-14 Magnetic Measurement Overview...

  • Page 31: Setup

    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 block connections).

  • Page 32: Rear Panel Definition

    3.3.2 Power Cord The Model 480 includes a three-conductor power cord. Line voltage is present 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.

  • Page 33: Coil Input Connection

    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.

  • Page 34: Terminal Block

    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.

  • Page 35: Basic Operation

    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.

  • Page 36: 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.

  • Page 37: General Keypad Operation

    Lake Shore Model 480 Fluxmeter User’s Manual KEYPAD DEFINITION (Continued) Coil Cal: Calibrates a user’s 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.

  • Page 38: 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...

  • Page 39: Dc Flux Measurement In Units Of V·s, Mx, Or Wb

    Lake Shore Model 480 Fluxmeter User’s Manual 4.6.2 DC Flux Measurement In Units of V·s, 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 COIL INPUT connections.

  • Page 40: Dc Flux Density Measurement In Units Of G Or T

    Lake Shore Model 480 Fluxmeter 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.

  • Page 41: Moment Measurement In Unit Of Wbcm

    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.

  • Page 42: Potential Measurement In Unit Of A

    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.

  • Page 43: Advanced Operation

    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.

  • Page 44: Coil Parameters

    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.

  • Page 45: Input Resistance

    (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.

  • Page 46: 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 .

  • Page 47: Area Turns (An)

    5.3.5 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.

  • Page 48: Making Measurements In Percent

    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. Its 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.

  • Page 49: Coil Calibration

    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.

  • Page 50: Storing New Coil Parameters Into Instrument Memory

    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. 5.6.3...

  • Page 51: Range Selection

    (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.

  • Page 52: 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.

  • Page 53: Manual Drift Adjustment

    5.9.2 Manual Drift Adjustment For manual drift adjustment the two 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.

  • Page 54: Dc And Ac Measurement Modes

    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.

  • Page 55: 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.

  • Page 56: Peak Hold And Peak Reset

    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.

  • Page 57: Peak Reset

    5.11.5 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 values can be displayed. The instrument defaults to displaying of both peaks.

  • Page 58: Display Resolution

    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.

  • Page 59: Alarm Setup

    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.

  • Page 60: Relay Setup

    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...

  • Page 61: Turning Alarm On And Off

    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.

  • Page 62: Monitor Analog Output

    Lake Shore Model 480 Fluxmeter User’s Manual Corrected Analog Output (Continued) Default: In default mode the corrected analog output mimics the monitor output. The output is scaled to V·s 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...

  • Page 63: External Reset

    400 ms for Dual Peak. 5.17 OPTIONAL 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.

  • Page 64: Resetting To Default Values

    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.
  • Page 65 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 ...... 000 .......Disabled *SRE Service Request Enable Register Report ..000 .......Disabled Interface Commands ADDR Set IEEE-488 Address ........12 ......12 BAUD Set Serial Interface Baud Rate ......
  • Page 66 Lake Shore Model 480 Fluxmeter User’s Manual This Page Intentionally Left Blank 5-24 Advanced Operation...

  • Page 67: Computer Interface Operation

    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.

  • Page 68: Ieee-488 Interface Settings

    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 Address or Terminator setting.

  • Page 69: Status Registers

    Bit Name – Not Used 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.
  • Page 70 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 QOPC common command. It indicates when the Model 480 has completed all selected pending operations. Computer Interface Operation...

  • Page 71: Ieee Interface Example Programs

    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.

  • Page 72: Gpib0 Setting Configuration

    Lake Shore Model 480 Fluxmeter User’s Manual Figure 6-1. GPIB0 Setting Configuration Figure 6-2. DEV 12 Device Template Configuration Computer Interface Operation...
  • Page 73 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).
  • Page 74 Lake Shore Model 480 Fluxmeter User’s Manual Table 6-1. IEEE-488 Interface Program Control Properties Current Name Property New Value Name lblExitProgram Label1 Caption Type “exit” to end program. Name lblCommand Label2 Caption Command Name lblResponse Label3 Caption Response Name txtCommand...
  • Page 75 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() 'Routine to handle Send button press gSend = True 'Set Flag to True...
  • Page 76 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.

  • Page 77: Typical National Instruments Gpib Configuration From Ibconf.exe

    Lake Shore Model 480 Fluxmeter User’s Manual IBCONF.EXE.eps Figure 6-3. Typical National Instruments GPIB Configuration from IBCONF.EXE Computer Interface Operation 6-11...
  • Page 78 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 $INCLUDE statement is necessary along with a correct path to the file QBDECL.BAS.

  • Page 79: Troubleshooting

    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.

  • Page 80: Serial I/O Interface

    • Only QIDN? and QRST Common Commands are usable. • Terminators are fixed to CRLF. • A query must be added to the end of a command string if the Model 480 must return information. (Over IEEE-488, the last query response is sent when addressed to talk). For example: ”UNITS 8;UNITS?”...

  • Page 81: Serial Interface Example Programs

    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. Refer to Paragraph 6.2.3.1 for instructions on how to setup the program.
  • Page 82 Lake Shore Model 480 Fluxmeter User’s Manual Table 6-5. Serial Interface Program Control Properties Current Name Property New Value Name lblExitProgram Label1 Caption Type “exit” to end program. Name lblCommand Label2 Caption Command Name lblResponse Label3 Caption Response Name txtCommand...
  • Page 83 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() 'Routine to handle Send button press gSend = True 'Set Flag to True...
  • Page 84 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.

  • Page 85: Troubleshooting

    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 included with the response.

  • Page 86: Ieee-488/Serial Interface Command Summary

    Lake Shore Model 480 Fluxmeter User’s Manual IEEE-488/SERIAL INTERFACE COMMAND SUMMARY Command Function Page Command Function Page Common Commands COILKH? Query Helmholtz Coil Constant .... 6-28 COILKP Set Potential Coil Constant ....6-28 *CLS Clear Interface ........6-21 COILKP? Query Potential Coil Constant ....6-28 *ESE Set Std.

  • Page 87: Command List Structure

    *ESR? Returned: <ESR bit weighting>. Format: nnn[term]. Remarks: 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 Weighting...
  • Page 88 Lake Shore Model 480 Fluxmeter User’s Manual IDN? Query Identification Input: *IDN? Returned: <manufacturer>, <model number>, <serial number>, <firmware date> Format: LSCI,MODEL480,aaaaaa,nnnnnn[term]. 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.
  • Page 89 Event Name TST? Query Self-Test Input: *TST? Returned: 0 or 1. Format: n[term]. Remarks: The Model 480 performs a self-test at power-up. 0 = no errors found, 1 = errors found. WAI Wait-to-Continue Input: *WAI Returned: Nothing. Remarks: Prevents execution of any further commands or queries until completion of all previous ones.
  • Page 90 Lake Shore Model 480 Fluxmeter User’s Manual ALARM Configure Alarm Function Off/On. Input: ALARM <off/on> Returned: Nothing. Remarks: Configures the alarm function. 0 = Off, 1 = On. ALARM? Query Alarm Function Off/On. Input: ALARM? Returned: 0 or 1. Format: n[term].
  • Page 91 Lake Shore Model 480 Fluxmeter User’s Manual ALML Set Alarm Low Point Value. ALML nnn.nnnEnn Input: Returned: Nothing. Remarks: Sets the low point of the alarm function. Enter up to 6 digits with decimal point in exponential form. Place decimal appropriate to range.
  • Page 92 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.
  • Page 93 Lake Shore Model 480 Fluxmeter User’s Manual COILA Set Coil Area. COILA nnn.nnnEnn Input: Returned: Nothing. Remarks: Sets coil area for current coil in units of cm . Enter up to 6 digits and a decimal point in exponential form.
  • Page 94 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 and a decimal point in exponential form.
  • Page 95 Remarks: 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).
  • Page 96 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.
  • Page 97 Lake Shore Model 480 Fluxmeter User’s Manual FILT Configure Display Filter Function Off/On. Input: FILT <off/on> Returned: Nothing. Remarks: 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.
  • Page 98 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.
  • Page 99 Remarks: Sets the serial number and date for the attached probe. A probe 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.
  • Page 100 Remarks: Returns the middle relay function. 0 = Manual Off, 1 = Manual On, 2 = Automatic. RNGAC Configure AC Range Parameter. Input: RNGAC <range> Returned: Nothing Remarks: Configures the Model 480 AC range. 0 = 30 mV·s, 1 = 3 mV·s, 2 = 300 V·s, 3 = 30 V·s. 6-34 Computer Interface Operation...
  • Page 101 Input: RNGAC? Returned: An integer from 0 to 3. Format: n[term]. Remarks: Returns the Model 480 AC range. 0 = 30 mV·s, 1 = 3 mV·s, 2 = 300 V·s, 3 = 30 V·s. RNGDC Configure DC Range Parameter. Input: RNGDC <range>...
  • Page 102 Lake Shore Model 480 Fluxmeter User’s Manual This Page Intentionally Left Blank 6-36 Computer Interface Operation...

  • Page 103: Accessories, Coils, And Probes

    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.
  • Page 104 Transverse Reference Magnet: 0.343 inch gap, 100 G, 1% RM-1/2 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. RM-2 Dual Mounting Shelf for Two Model 480 Fluxmeters.

  • Page 105: Field Measuring Probes

    Lake Shore Model 480 Fluxmeter User’s Manual 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.

  • Page 106: Cm Field Probe

    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.

  • Page 107: Helmholtz Coils

    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.

  • Page 108: Model Fh-6 Helmholtz Coil

    Lake Shore Model 480 Fluxmeter User’s Manual P-480-7-4.bmp Figure 7-4. Model FH-6 Helmholtz Coil P-480-7-5.bmp Figure 7-5. Model FH-12 Helmholtz Coil Accessories, Coils, and Probes...

  • Page 109: Reference Magnets

    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 Alnico V or VI magnets for long-term stability.

  • Page 110: Model Rm-1/2 Half-Rack Mounting Kit

    Lake Shore Model 480 Fluxmeter User’s Manual C-480-7-7.eps Figure 7-7. Model RM-1/2 Half-Rack Mounting Kit C-480-7-8.eps Figure 7-8. Model RM-2 Dual Rack-Mount Shelf Accessories, Coils, and Probes...

  • Page 111: Service

    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.

  • Page 112: Identification Of Electrostatic Discharge Sensitive Components

    Lake Shore Model 480 Fluxmeter User’s Manual 8.2.1 Identification of Electrostatic Discharge Sensitive Components Below are various industry symbols used to label components as ESDS: 8.2.2 Handling Electrostatic Discharge Sensitive Components Observe all precautions necessary to prevent damage to ESDS components before attempting installation.

  • Page 113: Fuse Replacement

    Lake Shore Model 480 Fluxmeter User’s Manual Power On/Off Screwdriver Fuse Switch Slot Dra wer F-480-8-1.eps Figure 8-1. Power Fuse Access FUSE REPLACEMENT Below is the procedure to remove and replace a line fuse. There are two basic power configurations: U.S.

  • Page 114: Rear Panel Connector Definitions

    Lake Shore Model 480 Fluxmeter User’s Manual REAR PANEL CONNECTOR DEFINITIONS The connectors on the rear panel of the Model 480 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.

  • Page 115: Relays And Analog Signals Terminal Block

    Lake Shore Model 480 Fluxmeter User’s Manual C-480-8-4.eps 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.

  • Page 116: Serial Interface Cable Wiring

    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...

  • Page 117: Ieee-488 Interface Connector

    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.

  • Page 118: Top Of Enclosure Removal And Replacement

    6. Connect power cord to rear of unit and set power switch to On (l). 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”...

  • Page 119: Error Messages

    C-480-8-7.eps Figure 8-7. Location of Operation Software EPROM 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.

  • Page 120: Calibration Procedure

    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 ranges of the Model 480. Monitor and Corrected Analog outputs are done in a similar fashion.

  • Page 121: Ac Peak Offset

    1. Short the input terminals of the Model 480. 2. Set Model 480 to AC, Dual Peak operation, 100 k 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).

  • Page 122: Dc And Dc Peak Calibration

    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 possible.

  • Page 123: Output Calibration

    Paragraphs 8.9.7.1 and 8.9.7.2. 8.9.7.1 Monitor Output Calibration 1. Connect Oscillator to Model 480 input terminals (observe ground) using the 1 µF series capacitor in series with the signal lead. 2. Connect DVM to Model 480 Monitor Output, set to AC.

  • Page 124: Finalize Calibration

    Lake Shore Model 480 Fluxmeter User’s Manual 8.9.7.2 Corrected Output Calibration 1. Connect DVM to Model 480 Corrected Output, set to DC. 2. Set Model 480 Analog output to manual, -100%. 3. Corrected Offset Constant = –(Voltmeter reading 1 + 10.000 Vdc) / 20.

  • Page 125: Appendix A - Glossary Of Terminology

    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 to perform flux density measurements in units of gauss (G) or tesla (T).
  • Page 126 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.
  • Page 127 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 10/4 ampere-turn. Named for William Gilbert (1540 –...
  • Page 128 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.
  • Page 129 Lake Shore Model 480 Fluxmeter User’s Manual permeability. Material parameter which is the ratio of the magnetic induction (B) to the magnetic field strength (H): µ = 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...
  • Page 130 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 (V·s), Webers (Wb), or Maxwells (Mx).
  • Page 131 Lake Shore Model 480 Fluxmeter User’s Manual APPENDIX B REFERENCE INFORMATION Table B-1. Conversion from CGS to SI Units Gaussian Conversion SI & Quantity Symbol & CGS emu Factor, C Rationalized mks Magnetic flux density, tesla (T), Wb/m –4 gauss (G)
  • Page 132 Lake Shore Model 480 Fluxmeter User’s Manual Table B-2. Recommended SI Values for Physical Constants Quantity Symbol Value (SI units) µ Permeability of Vacuum 4 × 10 Speed of Light in Vacuum 2.9979 × 10  Permitivity of Vacuum = (µ...

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