Lake Shore Cryotronics 455 User Manual
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Lake Shore Cryotronics 455 User Manual

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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: 1.5
User's Manual
Model 455
DSP Gaussmeter
Lake Shore Cryotronics, Inc.
575 McCorkle Blvd.
Westerville, Ohio 43082-8888 USA
E-mail Addresses:
sales@lakeshore.com
service@lakeshore.com
Visit Our Website At:
www.lakeshore.com
Fax: (614) 891-1392
Telephone: (614) 891-2243
P/N 119-040
13 May 2014

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  • Page 1 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.
  • Page 2 Lake Shore Model 455 Gaussmeter 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 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 455 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 455 Gaussmeter User’s Manual...
  • Page 5 To qualify for the CE Mark, the Model 455 meets or exceeds the 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...

  • Page 7: Table Of Contents

    Lake Shore Model 455 Gaussmeter User’s Manual TABLE OF CONTENTS Chapter/Section Title Page INTRODUCTION ........................1-1 GENERAL ..........................1-1 DESCRIPTION ........................1-1 1.1.1 Measurement Features ....................... 1-2 1.1.2 Instrument Probe Features ....................1-2 1.1.3 Display and Interface Features ................... 1-3 SPECIFICATIONS .........................
  • Page 8 Lake Shore Model 455 Gaussmeter User’s Manual TABLE OF CONTENTS (Continued) Chapter/Section Title Page 4.2.1 Display Units ........................4-2 4.2.2 Display and LED Annunciators ................... 4-2 KEYPAD DEFINITION ......................4-3 4.3.1 Key Descriptions ......................... 4-3 4.3.2 General Keypad Operation....................4-4 DISPLAY SETUP ........................
  • Page 9 Lake Shore Model 455 Gaussmeter User’s Manual TABLE OF CONTENTS (Continued) Chapter/Section Title Page ADVANCED OPERATION......................5-1 GENERAL ..........................5-1 PROBE MANAGEMENT ......................5-1 5.1.1 Clear Probe Zero Calibration ....................5-1 5.1.2 Probe Serial Number ......................5-1 5.1.3 Field and Temperature Compensation ................5-1 5.1.4...
  • Page 10 7.5.1 Hall Generator Handling ....................7-10 7.5.2 Hall Generator Lead Wires ....................7-10 7.5.3 Using a Hall Generator with the Model 455 ..............7-10 7.5.4 Attachment To A User Programmable Cable ..............7-11 7.5.5 Hall Generator Specifications .................... 7-12 HELMHOLTZ COIL LOW FIELD STANDARDS ..............7-15 REFERENCE MAGNETS .....................
  • Page 11 Lake Shore Model 455 Gaussmeter User’s Manual LIST OF ILLUSTRATIONS Figure No. Title Page Model 455 Front Panel ..........................1-1 Model 455 System Block Diagram ....................... 2-2 DC Measurement Block Diagram ......................... 2-3 RMS Narrow Band AC Block Diagram ......................2-3 RMS Wide Band AC Block Diagram......................
  • Page 12 Lake Shore Model 455 Gaussmeter User’s Manual LIST OF TABLES Table No. Title Page Default Parameter Values .......................... 4-27 Binary Weighting of an 8 Bit Register ......................6-6 Register Clear Methods ..........................6-6 Programming Example to Generate an SRQ ..................... 6-10 IEEE-488 Interface Program Control Properties ..................

  • Page 13: Introduction

    Advanced features including DC to 20 kHz AC frequency response, peak field detection to 50 µs pulse widths, DC accuracy of 0.075%, and up to 5¾ digits of display resolution make the Model 455 ideal for both industrial and research applications. For added functionality and value, the Model 455 includes a standard Lake Shore Hall probe.

  • Page 14: Measurement Features

    Lake Shore offers a full complement of standard and custom Hall effect probes in a variety of sizes and sensitivities. One of ten common standard Hall probes is included with the Model 455. Refer to Section 7.2.3 for a list of available probes, including details on the 1 of 10 Hall probes you can choose to receive with the Model 455.

  • Page 15: Display And Interface Features

    Keeping probes and their extensions from getting mixed up can become a problem when more than one probe is in use. The Model 455 alleviates most of the hassle by allowing users to match probes to extensions in the field.

  • Page 16: Specifications

    The output is produced by the micro-processor through a 16-bit D/A converter updated at 30 readings per second. Computer Interface. Two computer interfaces are included with the Model 455: serial (RS-232C) and parallel (IEEE-488). Both allow setup of all instrument parameters and read-back of measured values. The reading rate over the interface is nominally 30 readings per second.
  • Page 17 Lake Shore Model 455 Gaussmeter User’s Manual Specifications (Continued) AC RMS Measurement Probe Type 4¾-digit Ranges resolution HST Probe 350 kG 000.01 kG 35 kG 00.001 kG 3.5 kG 0.0002 kG 350 G 000.02 G 35 G 00.020 G HSE Probe 35 kG 00.001 kG...
  • Page 18 Lake Shore Model 455 Gaussmeter User’s Manual Specifications (Continued) Front Panel Display type: 2 line × 20 character, vacuum fluorescent with 9 mm high characters Display resolution: To ±5¾ digits Display update rate: 5 rdg/s Display units: gauss (G), tesla (T), oersted (Oe), and ampere per meter (A/m) Units multipliers: µ, m, k, M...
  • Page 19 The uncalibrated version involves the operator loading the matching probe data file into the cable PROM directly from the Model 455 front panel. Additional errors caused by the uncalibrated extension cables are ±0.02% of field reading error and 1 °C temperature reading error...

  • Page 20: Safety Summary

    Lake Shore Cryotronics, Inc. assumes no liability for Customer failure to comply with these requirements. The Model 455 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 21: Background

    This is referred to as the Nyquist frequency. In the case of the Model 455, the ADC is sampled at 40 kHz in wide band AC mode.

  • Page 22: Model 455 System Overview

    DSP Gaussmeter., refer to the Model 455 system block diagram, Figure 2-1. The Model 455 uses a 100 mA, 5 kHz square wave excitation to drive the Hall sensor in DC mode and narrow band AC mode. In wide band AC mode, it uses a 100 mA, DC excitation to drive the sensor. The Hall voltage produced by the sensor is fed back into the instrument and sent through a programmable gain stage.

  • Page 23: Rms Measurement

    2.1.6 RMS Measurement The Model 455 offers two different modes of AC measurement, narrow-band and wide-band. In narrow-band AC measurement, the instrument uses a 100 mA, 5 kHz, square wave excitation current. This type of excitation provides the benefit of noise cancellation characteristics of the product detector but limits the maximum frequency to approximately 1 kHz.

  • Page 24: Flux Density Overview

    Lake Shore Model 455 Gaussmeter User’s Manual FLUX DENSITY OVERVIEW 2.2.1 What is Flux Density? A magnetic field can be envisioned as consisting of flux lines (). A unit of flux is called a line. In the cgs system, one line of flux equals one maxwell (Mx).

  • Page 25: Active Area

    Lake Shore Model 455 Gaussmeter User’s Manual 2.3.1 Active Area The Hall generator assembly contains the sheet of semiconductor material to which the four contacts are made. This entity is normally called a “Hall plate.” The Hall plate is, in its simplest form, a rectangular shape of fixed length, width and thickness.

  • Page 26: Polarity

    Lake Shore Model 455 Gaussmeter User’s Manual 2.3.2 Polarity If the control current enters the red lead (with +I connected to the positive terminal of the current supply), and the magnetic field direction B is as shown in Figure 2-6, a positive Hall voltage will be generated at the +V lead.

  • Page 27: Installation

    Check off each item on the packing list as it is unpacked. Instruments themselves may be shipped as several parts. The items included with the Model 455 are listed below. Contact Lake Shore immediately if there is a shortage of parts or accessories.

  • Page 28: Rear Panel Definition

    REAR PANEL DEFINITION This paragraph defines the rear panel of the Model 455. See Figure 3-1. Readers are referred to paragraphs that contain installation instructions and connector pin-outs for each feature. A summary of connector pin-outs is provided in Section 8.10.

  • Page 29: Line Input Assembly

    Line Fuse and Fuse Holder The line fuse is an important safety feature of the Model 455. If a fuse ever fails, it is important to replace it with the value and type indicated on the rear panel for the line voltage setting. The letter T on the fuse rating indicates that the instrument requires a time-delay or slow-blow fuse.

  • Page 30: Probe Input Connection

    A new probe can be connected at any time even while the instrument is turned on. No parameters need to be entered into the Model 455 for a Lake Shore probe. However, the Zero Probe function should be performed the first time a probe is used with the instrument and periodically during use.

  • Page 31: Probe Operation

    Lake Shore Model 455 Gaussmeter User’s Manual Figure 3-3. Maximum Flexible Probe Bend Radius 3.5.2 Probe Operation In the DC mode of operation, the orientation of the probe affects the polarity reading of the gaussmeter. On a transverse probe, the Lake Shore name printed on the handle indicates the side for positive (+) flux entry. On an axial probe, positive (+) flux entry is always from the front of the probe.

  • Page 32: Probe Accuracy Considerations

    Lake Shore Model 455 Gaussmeter User’s Manual 3.5.3 Probe Accuracy Considerations The user must consider all the possible contributors to the accuracy of the reading. Both the probe and gaussmeter have accuracy specifications that may impact the actual reading. The probe should be zeroed before making critical measurements.

  • Page 33: Auxiliary I/O Connection

    16-bit, D/A converter updated at 30 readings per second. Relay1 and Relay 2: The Model 455 has two mechanical relays designated Relay 1 and Relay 2. The relays are most commonly associated with the high and low alarms, but they can also be controlled manually and used for other purposes.

  • Page 34: Rack Mounting

    Lake Shore Model 455 Gaussmeter User’s Manual RACK MOUNTING The Model 455 can be installed into a 19-inch rack mount cabinet using the optional Lake Shore Model RM½ Rack- Mount Kit, or the Model RM2 Dual Rack-Mount Shelf. The Rack-Mount Kit contains mounting ears, panel, handles, and screws that adapt the front panel to fit into a 3.5 inch tall, full rack space.
  • Page 35 Lake Shore Model 455 Gaussmeter User’s Manual Figure 3-8. Model RM2 Dual Rack-Mount Shelf (P/N 4026) Installation...
  • Page 36 Lake Shore Model 455 Gaussmeter User’s Manual This Page Intentionally Left Blank 3-10 Installation...

  • Page 37: Operation

    DSP Gaussmeter When the Model 455 is turned on the display reads Lake Shore for a few seconds and the alarm beeper sounds briefly to indicate the instrument is initializing. Most instrument setup parameter values are retained when power is off with only a few exceptions.

  • Page 38: Display Definition

    Lake Shore Model 455 Gaussmeter User’s Manual DISPLAY DEFINITION In normal operation, the two row by twenty character vacuum fluorescent display provides readings defined by the selected measurement features on the top row, and special information or readings on the bottom row. The bottom row can be configured under most operating conditions (refer to Section 4.4).

  • Page 39: Keypad Definition

    On steady when the alarm feature is on, blinks when the alarm is active . Indicates that the instrument is under remote control of the computer interface. Remote KEYPAD DEFINITION The Model 455 has 22 keys separated into 3 groups on the instrument front panel. 4.3.1 Key Descriptions Local...

  • Page 40: General Keypad Operation

    The user may configure the bottom row of the display. 4.4.1 Two-Line Display Configuration The Model 455 can be configured to display different values on the bottom line of the display. The following list gives a description of each setting. Blank No Bottom line display.

  • Page 41: Display Brightness

    Lake Shore Model 455 Gaussmeter User’s Manual 4.4.2 Display Brightness To change the brightness, press and hold the Display key for approximately 4 seconds. The display configuration screen appears as a prompt for display brightness. Operating continuously at 100% brightness will shorten the life of the display.

  • Page 42: Dc Measurement Mode

    To measure static or slowly changing fields, press the DC key on the front panel. In DC measurement mode, the keypad and functionality of the Model 455 is optimized to provide the best interaction for DC measurements. The keypad features are described in paragraphs 4.6.1 through 4.6.7.

  • Page 43: Dc Operation Resolution And Filtering

    DC Operation Resolution and Filtering The firmware linear filter is an integral part of the Model 455 DC measurement. It is directly related to measurement resolution, frequency response, and reading rate. Reading rates up to 30 readings per second are only available over the computer interface, but the display will update at 5 readings per second independent of filter configuration.

  • Page 44: Dc Operation Max Hold

    Probe Offset Larger Than Expected The Model 455 will continue to operate with the offset correction, but it will be up to the individual to investigate the nature of the offset. 4.6.4...
  • Page 45 Lake Shore Model 455 Gaussmeter User’s Manual Example: If the present maximum reading is +20 kG and the instrument measures –35 kG, the –35 kG becomes the new maximum reading. If the minimum reading is –3.0 kG and the instrument measures –1.5 kG, the –1.5 kG becomes the new minimum reading.

  • Page 46: Max/Min Display Setting

    Lake Shore Model 455 Gaussmeter User’s Manual 4.6.4.2 Max/Min Display Setting Typically the maximum reading (Max) is displayed on the top line when the Max Hold feature is on. Sometimes it may be beneficial to display the minimum reading (Min) on the top line instead of the maximum. The user may also display both the maximum and minimum readings, with the maximum reading on the top line and the minimum reading on the bottom line.
  • Page 47 In the DC measurement mode, the signal available at Analog Output 1 may only be useful as a verification of the Model 455 measurement hardware. The signal contains the 5 kHz modulation of the current source making it difficult to use as an accurate field representation.

  • Page 48: Rms Measurement Mode

    Measurement resolution (noise floor) varies depending on probe and application, but the Model 455 can typically measure signals as small as 0.1% of full scale range.

  • Page 49: Rms Measurement Band

    RMS Operation Frequency Measurement With certain limitations, the Model 455 Gaussmeter is capable of measuring and displaying the frequency of an AC magnetic field. The frequency is calculated using a zero-crossing counter, so the indicated value is only valid for robust fields with a single, dominant frequency.

  • Page 50: Rms Operation Max Hold

    Lake Shore Model 455 Gaussmeter User’s Manual 4.7.5 RMS Operation Max Hold The Max Hold function captures the largest (Maximum) or smallest (Minimum) RMS field readings since the last Reset press. To turn the Max Hold feature on, press the Max Hold key. The following screen will appear for approximately 3 seconds.

  • Page 51: Rms Operation Analog Output 1 And 2

    If the instrument is configured in Narrow Band RMS measurement mode, Analog Output 1 may only be useful as a verification of the Model 455 measurement hardware. The signal contains the 5 kHz modulation of the current source making it difficult to use as an accurate field representation.

  • Page 52: Peak Measurement Mode

    To measure pulsed or periodic fields, press the Peak key on the front panel. In Peak measurement mode, the keypad and functionality of the Model 455 is optimized to provide the best interaction for Peak measurements. The keypad features are described in the following paragraphs.

  • Page 53: Peak Operation Periodic/Pulse Setup

    Lake Shore Model 455 Gaussmeter User’s Manual 4.8.2 Peak Operation Periodic/Pulse Setup The Peak measurement mode can be configured to measure pulsed fields or the maximum amplitude of periodic fields. In periodic mode, the instrument follows the peak amplitude of the periodic signal. This may be useful in determining additional information about AC fields, such as crest factor.

  • Page 54: Peak Operation Relative

    Lake Shore Model 455 Gaussmeter User’s Manual 4.8.6 Peak Operation Relative The relative function lets the user see small variations in larger fields. When the relative function is on, the relative readings will appear on the top line of the display including the small delta sign (s) signifying the relative display.

  • Page 55: Temperature Measurement

    TEMPERATURE MEASUREMENT The Model 455 is capable of measuring the temperature of the probe, if the probe is equipped with a temperature sensor and a temperature compensation table. The probe temperature can be displayed as Kelvin or in degrees Celsius. Refer to Section 4.4.1 for display setup.
  • Page 56 Lake Shore Model 455 Gaussmeter User’s Manual The alarm may be configured to use the magnitude of the field reading only (ignoring the sign), or to include the sign and treat the readings algebraically. To configure the alarm for magnitude or algebraic mode, press and hold the Alarm key for approximately 4 seconds.
  • Page 57 Alarm_Inside_A.eps The Model 455 has an audible alarm annunciator or beeper. The beeper will sound when the instrument is in an active alarm state. If the sound of the beeper is not appropriate for your application, it can be turned on or off by the user.

  • Page 58: 4.11 Relays

    4.11 RELAYS The Model 455 has two mechanical relays designated Relay 1 and Relay 2. The relays are most commonly associated with the high and low alarms, but they can also be controlled manually and used for other purposes. Both relays default to their normal state when instrument power is turned off.

  • Page 59: Analog Output 3

    Lake Shore Model 455 Gaussmeter User’s Manual 4.12 ANALOG OUTPUT 3 The Analog Output 3 provides a DC voltage proportional to the displayed field. The displayed field reading may be corrected for probe nonlinearity, zero offset, and temperature. This output has an update rate of 30 readings per second.
  • Page 60 Lake Shore Model 455 Gaussmeter User’s Manual Enter for Analog Out High +3.50000 kG Use the data entry keys to enter the high setpoint between ±350 kG or equivalent depending on selected units. Enter the numeric value first. Press Enter to accept the new value and advance to the units multiplier. Use the s or t key to select a units multiplier of µ, m, blank, k or M.

  • Page 61: Analog Output 3 Polarity

    Lake Shore Model 455 Gaussmeter User’s Manual 4.12.2 Analog Output 3 Polarity The Analog Output 3 can be configured to operate either in a unipolar fashion (output from 0 volts to +10 volts) or in a bipolar fashion (output from –10 volts to +10 volts).

  • Page 62: 4.13 Locking The Keypad

    Lake Shore Model 455 Gaussmeter User’s Manual 4.13 LOCKING THE KEYPAD The keypad lock feature prevents accidental changes to parameter values. When the keypad is locked all parameter values may be viewed but none may be changed from the front panel.

  • Page 63: 4.14 Default Parameter Values

    Lake Shore Model 455 Gaussmeter User’s Manual 4.14 DEFAULT PARAMETER VALUES It is sometimes desirable to reset instrument parameters to their default values. This data is stored in EEPROM memory. Instrument calibration is not affected by this operation. The firmware version date is also displayed during this sequence.
  • Page 64 Lake Shore Model 455 Gaussmeter User’s Manual This Page Intentionally Left Blank 4-28 Operation...

  • Page 65: Advanced Operation

    Probe Serial Number The serial number of the probe presently attached can be viewed from the display of the Model 455. This feature can also be used to check the programming of extension cables. To view the serial number, press the Probe key. The following screen will appear for approximately 6 seconds.

  • Page 66: Extension Cable

    Keeping probes and their extensions from getting mixed up can become a problem when more than one probe is in use. The Model 455 alleviates some of the difficulty by allowing users to match probes to extensions in the field.

  • Page 67: Hall Generator

    Lake Shore Model 455 Gaussmeter User’s Manual Visually verify that a valid HMPEC cable is attached to the Model 455. Press Enter to copy the probe characteristics to the memory of the extension cable. Press Escape to cancel the process and return to the normal display.

  • Page 68: Ohms Measurement Mode

    Ohms Measurement Mode The Model 455 may be configured to make a 4-lead resistive measurement. If the sensitivity of the probe is set to 0, the instrument will read in ohms. Instrument features are limited in this mode. The following ranges are available in this mode: 350 µ, 3.5 m, 35 m, 350 m, and 3.5 .

  • Page 69: Computer Interface Operation

    4005) is required to use the IEEE-488 Interface and the Auxiliary connector at the same time. Cable lengths are limited to 2 meters for each device and 20 meters for the entire bus. The Model 455 can drive a bus with up to 10 loads.

  • Page 70: Changing Ieee-488 Interface Parameters

    6.1.2 Remote/Local Operation Normal operations from the keypad are referred to as ‘Local’ operations. The Model 455 can also be configured for ‘Remote’ operations via the IEEE-488 interface or the Local key. The Local key will toggle between ‘Remote’ and ‘Local’...

  • Page 71: Common Commands

    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 (?). Model 455 common commands are detailed in Section 6.3 and summarized in Table 6-9.

  • Page 72: Status System

    6.1.4.1 Overview The Model 455 implements a status system compliant to the IEEE 488.2 – 1992 standard. The status system provides a method of recording and reporting instrument information and is typically used to control the Service Request (SRQ) interrupt line. A diagram of the status system is shown in Figure 6-1. The status system is made up of register sets, the Status Byte register, and the Service Request Enable register.
  • Page 73 Lake Shore Model 455 Gaussmeter User’s Manual Figure_6-1.bmp Figure 6-1. Model 455 Status System Remote Operation...
  • Page 74 Lake Shore Model 455 Gaussmeter User’s Manual 6.1.4.1.5 Reading Registers Any register in the status system may be read using the appropriate query command. Some registers clear when read, others do not. Refer to Section 6.1.4.1.7. The response to a query will be a decimal value which corresponds to the binary-weighted sum of all bits in the register, refer to Table 6-1.

  • Page 75: Status Register Sets

    Lake Shore Model 455 Gaussmeter User’s Manual 6.1.4.2 Status Register Sets As shown in Figure 6-1, there are two register sets in the status system of the Model 455: Standard Event Status Register and Operation Event Register. 6.1.4.2.1 Standard Event Status Register Set The Standard Event Status Register reports the following interface related instrument events: power on detected, command syntax errors, command execution errors, query errors, operation complete.

  • Page 76: Status Byte And Service Request (Srq)

    Lake Shore Model 455 Gaussmeter User’s Manual Figure_6-3.bmp Figure 6-3. Operation Event Register 6.1.4.3 Status Byte and Service Request (SRQ) As shown in Figure 6-1, the Status Byte Register receives the summary bits from the two status register sets and the message available summary bit from the output buffer.
  • Page 77 Lake Shore Model 455 Gaussmeter User’s Manual 6.1.4.3.2 Service Request Enable Register The Service Request Enable Register is programmed by the user and determines which summary bits of the Status Byte may set bit 6 (RQS/MSS) to generate a Service Request. Enable bits are logically ANDed with the corresponding summary bits, see Figure 6-4.
  • Page 78 The bus controller can, for example, send a query command to the Model 455 and then wait for MAV to set. If the MAV bit has been enabled to initiate an SRQ, the user’s program can direct the bus controller to look for the SRQ leaving the bus available for other use.

  • Page 79: Ieee Interface Example Programs

    Lake Shore Model 455 Gaussmeter User’s Manual 6.1.5 IEEE Interface Example Program A Visual Basic program is included to illustrate the IEEE-488 communication functions of the instrument. Refer to Section 6.1.5.1 for instructions on how to setup the program. The Visual Basic code is provided in Table 6-5. A description of program operation is provided in Section 6.1.5.3.
  • Page 80 Lake Shore Model 455 Gaussmeter User’s Manual Figure 6-5. GPIB0 Setting Configuration Figure 6-6. DEV 12 Device Template Configuration 6-12 Remote Operation...

  • Page 81: Visual Basic Ieee-488 Interface Program Setup

    Lake Shore Model 455 Gaussmeter User’s Manual 6.1.5.2 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 Section 6.1.5.1).
  • Page 82 Lake Shore Model 455 Gaussmeter User’s Manual Table 6-4. IEEE-488 Interface Program Control Properties Current Name Property New Value Label1 Name lblExitProgram Type “exit” to end program. Caption Label2 Name lblCommand Caption Command Label3 Name lblResponse Caption Response Text1 Name...
  • Page 83 Lake Shore Model 455 Gaussmeter User’s Manual Table 6-5. 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 84: Program Operation

    Lake Shore Model 455 Gaussmeter User’s Manual 6.1.5.3 Program Operation Once the 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 85: Serial Interface Overview

    SERIAL INTERFACE OVERVIEW The serial interface used in the Model 455 is commonly referred to as an RS-232C interface. RS-232C is a standard of the Electronics Industries Association (EIA) that describes one of the most common interfaces between computers and electronic equipment.

  • Page 86: Hardware Support

    Hardware Support The Model 455 interface hardware supports the following features. Asynchronous timing is used for the individual bit data within a character. This timing requires start and stop bits as part of each character so the transmitter and receiver can resynchronized between each character.

  • Page 87: Message Flow Control

    Lake Shore Model 455 Gaussmeter User’s Manual Message Strings (Continued) A query string is issued by the computer and instructs the instrument to send a response. The query format is: <query mnemonic><?><space><parameter data><terminators>. Query mnemonics are often the same as commands with the addition of a question mark. Parameter data is often unnecessary when sending queries.

  • Page 88: Visual Basic Serial Interface Program Setup

    Lake Shore Model 455 Gaussmeter User’s Manual 6.2.7.1 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.
  • Page 89 Lake Shore Model 455 Gaussmeter User’s Manual Table 6-7. Serial Interface Program Control Properties Current Name Property New Value Label1 Name lblExitProgram Type “exit” to end program. Caption Label2 Name lblCommand Caption Command Label3 Name lblResponse Caption Response Text1 Name...
  • Page 90 Lake Shore Model 455 Gaussmeter User’s Manual Table 6-8. 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 91: Program Operation

    Lake Shore Model 455 Gaussmeter User’s Manual 6.2.7.2 Program Operation Once the 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 92: Command Summary

    Lake Shore Model 455 Gaussmeter User’s Manual COMMAND SUMMARY This paragraph provides a listing of the IEEE-488 and Serial Interface Commands. A summary of all the commands is provided in Table 6-9. All the commands are detailed in Section 6.3.1, presented in alphabetical order.
  • Page 93 Lake Shore Model 455 Gaussmeter User’s Manual Table 6-9. Command Summary Command Function Page Command Function Page MODE Remote Interface Mode Cmd ......6-31 Clear Interface Cmd..........6-26 MODE? Remote Interface Mode Query ......6-31 Standard Event Status Enable Register Cmd ..6-26 OPST? Operational Status Query ........

  • Page 94: Interface Commands (Alphabetical Listing)

    Lake Shore Model 455 Gaussmeter User’s Manual 6.3.1 Interface Commands (Alphabetical Listing) *CLS Clear Interface Command *CLS [term] Input: Remarks: Clears the bits in the Standard Event Status Register and Operation Event Register and terminates all pending operations. Clears the interface, but not the instrument. The related instrument command is *RST.
  • Page 95 Input: Returned: <status>[term] Format: <status> 0 = No errors found, 1 = Errors found Remarks: The Model 455 reports status based on test done at power up. *WAI Wait-to-Continue Command *WAI [term] Input: Remarks: This command is not supported in the Model 455.
  • Page 96 Lake Shore Model 455 Gaussmeter User’s Manual ALARM Alarm Parameter Command ALARM <off/on>, <mode>, <low value>, <high value>,<out/in>[term] Input: Format: n,n,nnn.nnnEnn,nnn.nnnEnn,n <off/on> Specifies alarm checking on or off: 0 = Off, 1 = On. <mode> Specifies checking magnitude(absolute value used) or algebraically(includes sign): 1 = Magnitude check, 2 = Algebraic check.
  • Page 97 Lake Shore Model 455 Gaussmeter User’s Manual ANALOG? Analog Output 3 Parameter Query ANALOG? [term] Input: Returned: <mode>, <polarity>, <low value>, <high value>, <manual value>, <voltage limit> [term] Format: n,n,nnn.nnnEnn,nnn.nnnEnn,nnn.nnnEnn (Refer to command for definition) AOUT? Analog Output 3 Data Query...
  • Page 98 4 = Relative setpoint DISPLAY 3[term] – Probe Temperature will be displayed on Line 2 if the probe is capable of Example: measuring temperature. The Frequency will also be displayed if the Model 455 is in RMS mode. DISPLAY? Display Configuration Query...
  • Page 99 Remote Interface Mode Command MODE <mode>[term] Input: Format: <mode> 0 = local, 1 = remote, 2 = remote with local lockout. MODE 2[term] – Places the Model 455 into remote mode with local lockout. Example: MODE? Remote Interface Mode Query MODE? [term] Input: Returned: <mode>[term]...
  • Page 100 Lake Shore Model 455 Gaussmeter User’s Manual OPST? Operational Status Query OPST? [term] Input: Returned: <bit weighting> [term] Format: Remarks: The integer returned represents the sum of the bit weighting of the operational status bits. Refer to Section 6.1.4.2.2 for a list of operational status bits.
  • Page 101 Lake Shore Model 455 Gaussmeter User’s Manual PRBSENS? Probe Sensitivity Query PRBSENS? [term] Input: Returned: <sensitivity>[term] nnn.nnnEnn Format: Remarks: Returns the probe sensitivity in mV/kG. PRBSNUM? Probe Serial Number Query PRBSNUM? [term] Input: Returned: <type>[term] Format: xxxxxxxxxx Remarks: Returns the probe serial number.
  • Page 102 <peak disp> Specifies display of peak reading: 1 = positive, 2 = negative, 3 = both. RDGMODE 1,3,1,1,1[term] – The Model 455 is configured for DC field measurement, DC resolution Example: of 5 digits, wide band rms filter mode, peak measurement mode is periodic, and positive peak readings will be displayed if the measurement mode is changed to peak.
  • Page 103 Lake Shore Model 455 Gaussmeter User’s Manual RDGREL? Relative Reading Query RDGREL? [term] Input: Returned: <relative reading>[term] nnn.nnnEnn Format: Remarks: Returns the relative field reading. RDGTEMP? Probe Temperature Reading Query RDGTEMP? [term] Input: Returned: <temperature>[term] nnn.nnnEnn Format: Remarks: Returns the probe temperature reading in a format based on the present temperature units.
  • Page 104 TUNIT Probe Temperature Units Command TUNIT <units>[term] Input: Format: <units> 1 = Celsius, 2 = Kelvin TUNIT 1[term] – Configures the Model 455 to report probe temperature in °C. Example: TUNIT? Probe Temperature Units Query TUNIT? [term] Input: Returned: <units>[term]...
  • Page 105 Field Units Command UNIT <units>[term] Input: Format: <units> 1 = Gauss, 2 = Tesla, 3 = Oersted, 4 = Amp/meter. UNIT 2[term] – Configures the Model 455 to report readings in Tesla. Example: UNIT? Field Units Query UNIT? [term] Input: Returned: <units>[term]...
  • Page 106 Lake Shore Model 455 Gaussmeter User’s Manual This Page Intentionally Left Blank 6-38 Remote Operation...

  • Page 107: Probes And Accessories

    Half-Rack Mounting Kit for One 1/2 Rack Gaussmeter. Half-length mounting panel and mounting RM-1/2 ears to attach one Model 455 to a 483 mm (19-inch) rack mount space. See Figure 3-7. Dual Mounting Shelf for Two 1/2 Rack Gaussmeters. Mounting panel and mounting ears to attach RM-2 two Model 455 DSP Gaussmeters to a 483 mm (19-inch) rack mount space.

  • Page 108: Lake Shore Standard Probes

    There are several types of Lake Shore Model 455 probes available: Axial, Gamma, Tangential, and Transverse — generally named for the Hall sensor orientation. Because the Model 455 covers such a wide magnetic field range (0.01 mG to 350 kG), three probe ranges are available: High Stability (HST), High Sensitivity (HSE), and Ultra-High Sensitivity (UHS).
  • Page 109 Multi-axis probes are available for multi-axis gaussmeters like the Lake Shore Model 460. These probes are not compatible with the Model 455. Frequency: Hall-effect gaussmeters, like the Model 455, are equally well suited for measuring either static, DC fields or periodic, AC fields but proper probe selection is required to get optimal performance.

  • Page 110: Radiation Effects On Gaussmeter Probes

    Lake Shore Model 455 Gaussmeter User’s Manual 7.3.2 Radiation Effects on Gaussmeter Probes The HST and HSE probes use a highly doped indium arsenide active material. The HST material is the more highly doped of the two and therefore will be less affected by radiation. Some general information relating to highly doped indium arsenide Hall generators is as follows: •...

  • Page 111: Probe Specifications

    Lake Shore Model 455 Gaussmeter User’s Manual 7.3.4 Probe Specifications Terminology used in Figures 7-2 thru 7-8 are defined as follows: Definition of Probe Terminology Usable Full-Scale Ranges Vs. Probe Type Type HST-3 HST-4 A = Distance from tip to center line of active area —...
  • Page 112 Lake Shore Model 455 Gaussmeter User’s Manual TRANSVERSE PROBES Transverse.bmp Figure 7-4. Definition of Lake Shore Transverse Probes TANGENTIAL PROBE Tangential.eps Figure 7-5. Definition of Lake Shore Tangential Probe Probes and Accessories...
  • Page 113 Lake Shore Model 455 Gaussmeter User’s Manual AXIAL PROBES Axial.bmp Figure 7-6. Definition of Lake Shore Axial Probes Probes and Accessories...
  • Page 114 Lake Shore Model 455 Gaussmeter User’s Manual FLEXIBLE TRANSVERSE PROBES Flexible_Transverse.bmp Figure 7-7. Definition of Lake Shore Flexible Transverse Probes FLEXIBLE AXIAL PROBE Flexible_Axial.eps Figure 7-8. Definition of Lake Shore Flexible Axial Probe Probes and Accessories...

  • Page 115: Probe Accessories

    Hall Generator Cable Assembly. The HMCBL Cable Assembly connects a discrete Hall generator to the Model 455 Gaussmeter. Refer to Section 7.5. Because of the many calibration intricacies, the user is responsible for measurement accuracy. Refer to Section 5.2 for programming instructions.

  • Page 116: Hall Generator

    Manganin wire is not usually acceptable for connection to a Hall generator because the resistance of Manganin wire is often too high. The gaussmeter current source is limited in compliance voltage. The Model 455 should not drive a load (Hall generator, wires in cryostat, and probe cable) greater than 50 . In fact, for best performance, the load should be less than 30 .

  • Page 117: Attachment To A User Programmable Cable

    The Model HMCBL-XX has a 15 pin D-sub connector on one end for direct attachment to the PROBE INPUT connection on the back panel of the Model 455 Gaussmeter. Four tinned wires are provided for connection to the Hall Generator. The leads may be soldered directly to these wires. The cable comes in two lengths: the HMCBL-6 is 2 meters (6 feet) and the HMCBL-20 is 6 meters (20 feet).

  • Page 118: Hall Generator Specifications

    Lake Shore Model 455 Gaussmeter User’s Manual 7.5.5 Hall Generator Specifications This section covers three types of Hall generators available from Lake Shore: HGCA & HGCT Series Cryogenic Hall generators (Figures 7-10 and 7-11) with specifications (Table 7-1), HGA Series Axial Hall generators (Figure 7-11) with specifications (Table 7-2), and HGT Series Transverse Hall generators (Figure 7-12) with specifications (Table 7-3).
  • Page 119 Lake Shore Model 455 Gaussmeter User’s Manual C-455-C-5.eps Figure 7-11. Axial Hall Generator HGA-3010, HGA-3030, and HGCA-3020 Dimensions Table 7-2. Axial Hall Generator Specifications Axial HGA-3010 HGA-3030 Description Instrumentation quality axial; low Instrumentation quality axial; phenolic temperature coefficient; phenolic package...
  • Page 120 Lake Shore Model 455 Gaussmeter User’s Manual C-455-C-7.eps Figure 7-12. Transverse Hall Generator HGT-1010 Dimensions Table 7-3. Transverse Hall Generator Specifications Transverse HGT-1010 HGT-3010 HGT-3030 Description General purpose transverse; Instrumentation quality Instrumentation quality 0.020 inch thick transverse; low temperature transverse ceramic package coefficient;...

  • Page 121: Helmholtz Coil Low Field Standards

    Lake Shore Model 455 Gaussmeter User’s Manual HELMHOLTZ COIL LOW FIELD STANDARDS Lake Shore offers three Helmholtz coils: 2.5-, 6-, and 12-inch diameter. Check the Lake Shore 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.
  • Page 122 Lake Shore Model 455 Gaussmeter User’s Manual Helmholtz_6.bmp Figure 7-14. Model MH-6 Helmholtz Coil Helmholtz_12.bmp Figure 7-15. Model MH-12 Helmholtz Coil 7-16 Probes and Accessories...

  • Page 123: Reference Magnets

    Lake Shore Model 455 Gaussmeter 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 124: Zero Gauss Chamber

    Lake Shore Model 455 Gaussmeter User’s Manual ZERO GAUSS CHAMBER NOTE: Use care to ensure the Zero Gauss Chamber does not become magnetized. Using a magnetized chamber to zero a probe can lead to erroneous field readings. It is a good practice to periodically degauss the chamber.

  • Page 125: Service

    RETURNING PRODUCTS TO LAKE SHORE If it is necessary to return the Model 455 or accessories for recalibration, repair or replacement, a Return Goods Authorization (RGA) number must be obtained from a factory representative or from the Lake Shore web site. Do not return a product to Lake Shore without an RGA number.

  • Page 126: Fuse Drawer

    FUSE DRAWER The fuse drawer supplied with the Model 455 holds the instrument line fuses and line voltage selection module. The drawer holds two 5 × 20 mm time delay fuses. It requires two good fuses of the same rating to operate safely.

  • Page 127: Error Messages

    Measurement No Probe There is no probe attached or the attached probe is damaged. The detected probe is not recognized as a valid Model 455 probe. Press Enter to Invalid Probe continue. A previous generation probe has been attached. Press Enter to continue. Measurement Incompatible Probe uses only nominal probe sensitivity.

  • Page 128: Electrostatic Discharge

    Lake Shore Model 455 Gaussmeter User’s Manual 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.

  • Page 129: Enclosure Top Removal And Replacement

    Lake Shore Model 455 Gaussmeter User’s Manual ENCLOSURE TOP 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 Set power switch to Off (O) and disconnect power cord from rear of unit.
  • Page 130 Lake Shore Model 455 Gaussmeter User’s Manual PCB Layout.bmp Figure 8-3. Location Of Important Internal Components Service...

  • Page 131: 8.10 Connector And Cable Definitions

    Lake Shore Model 455 Gaussmeter User’s Manual Firmware Replacement (Continued) CAUTION: The ICs are Electrostatic Discharge Sensitive (ESDS) devices. Wear shock-proof wrist straps (resistor limited to <5 mA) to prevent injury to service personnel and to avoid inducing an Electrostatic Discharge (ESD) into the device.
  • Page 132 Lake Shore Model 455 Gaussmeter User’s Manual Probe_Input.bmp Description Description V input – V input + No Connection No Connection V temp + EEPROM GND I temp + EEPROM VCC I temp – EEPROM CLK V temp – EEPROM DATA I hall –...

  • Page 133: Serial Interface Cable Wiring

    7 - DTR (tied to 4) 8 - CTS (in) 8 - NC 7 - RTS (out) 9 - NC 9 - NC NOTE: Same as null modem cable design except PC CTS is provided from the Model 455 on DTR. Service...

  • Page 134: Ieee-488 Interface Connector

    The total length of cable allowed in a system is 2 meters for each device on the bus, or 20 meters maximum. The Model 455 can drive a bus of up to 10 devices. A connector extender is required to use the IEEE-488 Interface and the Auxiliary I/O connector at the same time.

  • Page 135: 8.11 Calibration Procedure

    The highest range for the 100 mA excitation current is calibrated by measuring the 3 Ω standard resistor. This resistor is measured by using the HP 3458 to measure the current source of the Model 455 and the voltage across the resistor. This configuration is only valid for this range because the accuracy of the HP3458 is unacceptable for the remaining Model 455 ranges.
  • Page 136 This section describes the method of calibrating the 10 mA current source that may be used for future Hall sensors. The five ranges of the Model 455 will need to be calibrated for each current setting. The highest range is for each current is calibrated using a 33.2 Ω...
  • Page 137 This section describes the method of calibrating the 1 mA current source that may be used for future Hall sensors. The five ranges of the Model 455 will need to be calibrated for each current setting. The highest range is for each current is calibrated using a 332 Ω...

  • Page 138: Temperature Measurement Calibration

    Model 455. These values are to be used whenever the outputs are accessed. The gain and offset values should also be checked to assure that they are reasonable in value and reject them if they fall outside a given range.
  • Page 139 Full Scale. Test this factor to be between -1 and 1. Record this value. 12. Send the Offset Correction Factor (OCF) to the Model 455 (CALZ 4,3,<OCF>). 13. Configure Analog Output 3 to manual mode, -100% (ANALOG 3,2,0,0,-100,10).

  • Page 140: Calibration Specific Interface Commands

    Lake Shore Model 455 Gaussmeter User’s Manual 8.11.5 Calibration Specific Interface Commands CALG Gain Calibration Constant Command CALG <type>, <range>, <value>[term] Input: Format: n,n,±nnnnnnn <type> Specifies the item to calibrate. Valid entries are: 1 = 100 mA hall current source...
  • Page 141 Lake Shore Model 455 Gaussmeter User’s Manual CALZ Zero Offset Calibration Constant Command CALZ <type>, <range>, <value>[term] Input: Format: n,n,±nnnnnnn <type> Specifies the item to calibrate. Valid entries are: 1 = 100 mA hall current source (not used) 2 = 10 mA hall current source (not used)
  • Page 142 Lake Shore Model 455 Gaussmeter User’s Manual HALLCS Hall Current Source Range Command HALLCS <range>[term] Input: Format: <range> Specifies the hall current source range. Valid entries are: 1 = 100 mA range 2 = 10 mA range 3 = 1 mA range...

  • Page 143: Units For Magnetic Properties

    Lake Shore Model 455 Gaussmeter User’s Manual APPENDIX A UNITS FOR MAGNETIC PROPERTIES Table A-1. Conversion from CGS to SI Units SI & Gaussian Conversion Quantity Symbol Rationalized mks & CGS emu Factor, C Magnetic flux density, tesla (T), Wb/m –4...
  • Page 144 Lake Shore Model 455 Gaussmeter User’s Manual Table A-2. Recommended SI Values for Physical Constants Quantity Symbol Value (SI units) µ –7 –1 Permeability of Vacuum 4 × 10 –1 Speed of Light in Vacuum 2.9979 × 10  –12 –1...

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