Model 421 - Lake Shore Cryotronics, Inc.

Model 421 - Lake Shore Cryotronics, Inc.
User’s Manual
Model 421
Gaussmeter
Lake Shore Cryotronics, Inc.
575 McCorkle Boulevard
Westerville, Ohio 43082-8888 USA
E-Mail Addresses:
[email protected]
[email protected]
Visit Our Website:
www.lakeshore.com
Fax: (614) 891-1392
Telephone: (614) 891-2243
Methods and apparatus disclosed and described herein have been developed solely on company funds of Lake Shore Cryotronics, Inc.
No government or other contractual support or relationship whatsoever has existed which in any way affects or mitigates proprietary
rights of Lake Shore Cryotronics, Inc. in these developments. Methods and apparatus disclosed herein may be subject to U.S. Patents
existing or applied for. Lake Shore Cryotronics, Inc. reserves the right to add, improve, modify, or withdraw functions, design
modifications, or products at any time without notice. Lake Shore shall not be liable for errors contained herein or for incidental or
consequential damages in connection with furnishing, performance, or use of this material.
Rev. 1.5
P/N 119-030
18 March 2004
Lake Shore Model 421 Gaussmeter User’s Manual
LIMITED WARRANTY STATEMENT
WARRANTY PERIOD: ONE (1) YEAR
1. Lake Shore warrants that this Lake Shore product (the
“Product”) will be free from defects in materials and
workmanship for the Warranty Period specified above (the
“Warranty Period”). If Lake Shore receives notice of any such
defects during the Warranty Period and the Product is shipped
freight prepaid, Lake Shore will, at its option, either repair or
replace the Product if it is so defective without charge to the
owner for parts, service labor or associated customary return
shipping cost. Any such replacement for the Product may be
either new or equivalent in performance to new. Replacement or
repaired parts will be warranted for only the unexpired portion of
the original warranty or 90 days (whichever is greater).
2. Lake Shore warrants the Product only if it has been sold by an
authorized Lake Shore employee, sales representative, dealer
or original equipment manufacturer (OEM).
3. The Product may contain remanufactured parts equivalent to
new in performance or may have been subject to incidental use.
4. The Warranty Period begins on the date of delivery of the
Product or later on the date of installation of the Product if the
Product is installed by Lake Shore, provided that if you schedule
or delay the Lake Shore installation for more than 30 days after
delivery the Warranty Period begins on the 31st day after
delivery.
5. This limited warranty does not apply to defects in the Product
resulting from (a) improper or inadequate maintenance, repair or
calibration, (b) fuses, software and non-rechargeable batteries,
(c) software, interfacing, parts or other supplies not furnished by
Lake Shore, (d) unauthorized modification or misuse, (e)
operation outside of the published specifications or (f) improper
site preparation or maintenance.
6. TO THE EXTENT ALLOWED BY APPLICABLE LAW, THE
ABOVE WARRANTIES ARE EXCLUSIVE AND NO OTHER
WARRANTY OR CONDITION, WHETHER WRITTEN OR
ORAL, IS EXPRESSED OR IMPLIED. LAKE SHORE
SPECIFICALLY DISCLAIMS ANY IMPLIED WARRANTIES OR
CONDITIONS OF MERCHANTABILITY, SATISFACTORY
QUALITY AND/OR FITNESS FOR A PARTICULAR PURPOSE
WITH RESPECT TO THE PRODUCT. Some countries, states
or provinces do not allow limitations on an implied warranty, so
the above limitation or exclusion might not apply to you. This
warranty gives you specific legal rights and you might also have
other rights that vary from country to country, state to state or
province to province.
7. TO THE EXTENT ALLOWED BY APPLICABLE LAW, THE
REMEDIES IN THIS WARRANTY STATEMENT ARE YOUR
SOLE AND EXCLUSIVE REMEDIES.
8. EXCEPT TO THE EXTENT PROHIBITED BY APPLICABLE
LAW, IN NO EVENT WILL LAKE SHORE OR ANY OF ITS
SUBSIDIARIES, AFFILIATES OR SUPPLIERS BE LIABLE FOR
DIRECT, SPECIAL, INCIDENTAL, CONSEQUENTIAL OR
OTHER DAMAGES (INCLUDING LOST PROFIT, LOST DATA
OR DOWNTIME COSTS) ARISING OUT OF THE USE,
INABILITY TO USE OR RESULT OF USE OF THE PRODUCT,
WHETHER BASED IN WARRANTY, CONTRACT, TORT OR
OTHER LEGAL THEORY, AND WHETHER OR NOT LAKE
SHORE HAS BEEN ADVISED OF THE POSSIBILITY OF
SUCH DAMAGES. Your use of the Product is entirely at your
own risk. Some countries, states and provinces do not allow the
exclusion of liability for incidental or consequential damages, so
the above limitation may not apply to you.
LIMITED WARRANTY STATEMENT (Continued)
9. EXCEPT TO THE EXTENT ALLOWED BY APPLICABLE LAW,
THE TERMS OF THIS LIMITED WARRANTY STATEMENT DO
NOT EXCLUDE, RESTRICT OR MODIFY, AND ARE IN
ADDITION TO, THE MANDATORY STATUTORY RIGHTS
APPLICABLE TO THE SALE OF THE PRODUCT TO YOU.
CERTIFICATION
Lake Shore certifies that this product has been inspected and
tested in accordance with its published specifications and that this
product met its published specifications at the time of shipment.
The accuracy and calibration of this product at the time of
shipment are traceable to the United States National Institute of
Standards and Technology (NIST); formerly known as the National
Bureau of Standards (NBS).
FIRMWARE LIMITATIONS
Lake Shore has worked to ensure that the Model 421 firmware is
as free of errors as possible, and that the results you obtain from
the instrument are accurate and reliable. However, as with any
computer-based software, the possibility of errors exists.
In any important research, as when using any laboratory
equipment, results should be carefully examined and rechecked
before final conclusions are drawn. Neither Lake Shore nor anyone
else involved in the creation or production of this firmware can pay
for loss of time, inconvenience, loss of use of the product, or
property damage caused by this product or its failure to work, or
any other incidental or consequential damages. Use of our product
implies that you understand the Lake Shore license agreement and
statement of limited warranty.
FIRMWARE LICENSE AGREEMENT
The firmware in this instrument is protected by United States
copyright law and international treaty provisions. To maintain the
warranty, the code contained in the firmware must not be modified.
Any changes made to the code is at the user’s risk. Lake Shore will
assume no responsibility for damage or errors incurred as result of
any changes made to the firmware.
Under the terms of this agreement you may only use the Model
421 firmware as physically installed in the instrument. Archival
copies are strictly forbidden. You may not decompile, disassemble,
or reverse engineer the firmware. If you suspect there are
problems with the firmware, return the instrument to Lake Shore for
repair under the terms of the Limited Warranty specified above.
Any unauthorized duplication or use of the Model 421 firmware in
whole or in part, in print, or in any other storage and retrieval
system is forbidden.
TRADEMARK ACKNOWLEDGMENT
Many manufacturers and sellers claim designations used to
distinguish their products as trademarks. Where those
designations appear in this manual and Lake Shore was aware of
a trademark claim, they appear with initial capital letters and the ™
®
or symbol.
CalCurve™, Carbon-Glass™, Cernox™, Duo-Twist™,
High-Temperature Cernox™, Quad-Lead™, Quad-Twist™,
Rox™, SoftCal™, and Thermox™ are trademarks of
Lake Shore Cryotronics, Inc.
®
®
MS-DOS and Windows/95/98/NT/2000 are trademarks of
Microsoft Corp.
NI-488.2™ is a trademark of National Instruments.
PC, XT, AT, and PS-2 are trademarks of IBM.
Copyright © 1999, 2000, 2003, and 2004 by Lake Shore Cryotronics, Inc. All rights reserved. No portion of this manual
may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical,
photocopying, recording, or otherwise, without the express written permission of Lake Shore.
A
Lake Shore Model 421 Gaussmeter User’s Manual
DECLARATION OF CONFORMITY
We:
Lake Shore Cryotronics, Inc.
575 McCorkle Blvd.
Westerville OH 43082-8888 USA
hereby declare that the equipment specified conforms to the following
Directives and Standards:
Application of Council Directives: .............................. 73/23/EEC
89/336/EEC
Standards to which Conformity is declared: .............. EN 61010-1:2001
Overvoltage II
Pollution Degree 2
EN 61326 A2:2001
Class A
Annex B
Model Number:.......................................................... 421
Ed Maloof
Printed Name
Vice President of Engineering
Position
B
Lake Shore Model 421 Gaussmeter User’s Manual
Electromagnetic Compatibility (EMC) for the Model 421 Gaussmeter
Electromagnetic Compatibility (EMC) of electronic equipment is a growing concern worldwide.
Emissions of and immunity to electromagnetic interference is now part of the design and manufacture
of most electronics. To qualify for the CE Mark, the Model 421 meets or exceeds the generic
requirements of the European EMC Directive 89/336/EEC as a CLASS A product. A Class A product
is allowed to radiate more RF than a Class B product and must include the following warning:
WARNING:
This is a Class A product. In a domestic environment, this product may
cause radio interference in which case the user may be required to take
adequate measures.
The instrument was tested under normal operating conditions with sensor and interface cables
attached. If the installation and operating instructions in the User’s Manual are followed, there should
be no degradation in EMC performance.
Pay special attention to instrument cabling. Improperly installed cabling may defeat even the best
EMC protection. For the best performance from any precision instrument, follow the grounding and
shielding instructions in the User’s Manual. In addition, the installer of the Model 421 should consider
the following:
•
Leave no unused or unterminated cables attached to the instrument.
•
Make cable runs as short and direct as possible.
• Do not tightly bundle cables that carry different types of signals.
C
Lake Shore Model 421 Gaussmeter User’s Manual
TABLE OF CONTENTS
Chapter/Paragraph
Title
Page
1
INTRODUCTION .................................................................................................................................... 1-1
1.0
GENERAL ........................................................................................................................... 1-1
1.1
PRODUCT DESCRIPTION................................................................................................. 1-1
1.2
SPECIFICATIONS .............................................................................................................. 1-3
1.3
SAFETY SUMMARY........................................................................................................... 1-4
1.4
SAFETY SYMBOLS............................................................................................................ 1-4
2
INSTALLATION ..................................................................................................................................... 2-1
2.0
GENERAL ........................................................................................................................... 2-1
2.1
INSPECTION AND UNPACKING ....................................................................................... 2-1
2.2
REPACKAGING FOR SHIPMENT ..................................................................................... 2-1
2.3
REAR PANEL DEFINITION................................................................................................ 2-2
2.4
LINE INPUT ASSEMBLY.................................................................................................... 2-3
2.4.1
Line Voltage and Fuse Verification.................................................................................. 2-3
2.4.2
Power Cord ...................................................................................................................... 2-3
2.4.3
Power Switch ................................................................................................................... 2-3
2.5
PROBE INPUT CONNECTION .......................................................................................... 2-3
2.5.1
Attachment To A Hall Generator...................................................................................... 2-4
2.6
CORRECTED AND MONITOR ANALOG OUTPUTS ........................................................ 2-4
2.7
RELAY TERMINAL BLOCK................................................................................................ 2-4
2.8
INITIAL SETUP AND SYSTEM CHECKOUT PROCEDURE ............................................. 2-5
3
OPERATION .......................................................................................................................................... 3-1
3.0
GENERAL ........................................................................................................................... 3-1
3.1
DEFINITION OF FRONT PANEL CONTROLS .................................................................. 3-1
3.1.1
Front Panel Keypad ......................................................................................................... 3-1
3.1.2
Front Panel Display ......................................................................................................... 3-2
3.1.3
General Keypad Operation .............................................................................................. 3-3
3.2
GAUSS/TESLA ................................................................................................................... 3-3
3.3
AC/DC ................................................................................................................................. 3-4
3.4
DISPLAY FILTER................................................................................................................ 3-4
3.5
MANUAL RANGE AND AUTO RANGE.............................................................................. 3-5
3.6
ZERO PROBE..................................................................................................................... 3-6
3.7
MAX HOLD AND MAX RESET........................................................................................... 3-6
3.8
RELATIVE........................................................................................................................... 3-7
3.9
ALARM AND RELAY .......................................................................................................... 3-7
3.10
ANALOG OUTPUTS ......................................................................................................... 3-10
3.11
INTERFACE PARAMETERS............................................................................................ 3-11
3.12
FAST DATA MODE........................................................................................................... 3-11
3.13
LOCKING AND UNLOCKING THE KEYPAD................................................................... 3-12
3.14
DISPLAY BRIGHTNESS .................................................................................................. 3-12
3.15
FACTORY DEFAULT SETTINGS .................................................................................... 3-12
3.16
PROBE CONSIDERATIONS ............................................................................................ 3-13
3.16.1
Changing Probes ........................................................................................................... 3-13
3.16.2
Probe Handling .............................................................................................................. 3-13
3.16.3
Probe Operation ............................................................................................................ 3-14
3.16.4
Probe Accuracy Considerations .................................................................................... 3-15
i
Lake Shore Model 421 Gaussmeter User’s Manual
TABLE OF CONTENTS (Continued)
Chapter/Paragraph
4
Title
Page
REMOTE OPERATION ..........................................................................................................................4-1
4.0
GENERAL............................................................................................................................4-1
4.1
SERIAL INTERFACE OVERVIEW ......................................................................................4-1
4.1.1
Physical Connection.........................................................................................................4-1
4.1.2
Hardware Support ............................................................................................................4-2
4.1.3
Character Format .............................................................................................................4-2
4.1.4
Message Strings...............................................................................................................4-2
4.1.5
Message Flow Control......................................................................................................4-3
4.1.6
Changing Baud Rate ........................................................................................................4-3
4.1.7
Serial Interface Basic Programs.......................................................................................4-4
4.1.8
Troubleshooting................................................................................................................4-9
4.2
SERIAL INTERFACE COMMAND SUMMARY...................................................................4-9
4.2.1
Interface Commands ......................................................................................................4-11
4.2.2
Device Specific Commands ...........................................................................................4-12
5 ACCESSORIES AND PROBES.............................................................................................................5-1
5.0
GENERAL............................................................................................................................5-1
5.1
ACCESSORIES...................................................................................................................5-1
5.2
LAKE SHORE STANDARD PROBES.................................................................................5-3
5.2.1
Probe Selection Criteria ...................................................................................................5-3
5.2.2
Radiation Effect on Gaussmeter Probes..........................................................................5-3
5.2.3
Probe Specifications.........................................................................................................5-4
5.3
HELMHOLTZ COIL LOW FIELD STANDARDS..................................................................5-8
5.4
REFERENCE MAGNETS..................................................................................................5-10
6 SERVICE.................................................................................................................................................6-1
6.0
GENERAL............................................................................................................................6-1
6.1
GENERAL MAINTENANCE PRECAUTIONS .....................................................................6-1
6.2
ELECTROSTATIC DISCHARGE ........................................................................................6-1
6.2.1
Identification of Electrostatic Discharge Sensitive Components ......................................6-2
6.2.2
Handling Electrostatic Discharge Sensitive Components ................................................6-2
6.3
LINE VOLTAGE SELECTION .............................................................................................6-2
6.4
FUSE REPLACEMENT .......................................................................................................6-3
6.5
REAR PANEL CONNECTOR DEFINITIONS......................................................................6-4
6.5.1
Serial Interface Cable Wiring ...........................................................................................6-6
6.6
TOP OF ENCLOSURE REMOVAL AND REPLACEMENT ................................................6-7
6.6.1
Removal Procedure..........................................................................................................6-7
6.6.2
Installation Procedure.......................................................................................................6-7
6.7
EPROM REPLACEMENT ...................................................................................................6-7
6.8
ERROR MESSAGES ..........................................................................................................6-8
APPENDIX A – GLOSSARY OF TERMINOLOGY ..................................................................................... A-1
APPENDIX B – UNITS FOR MAGNETIC PROPERTIES............................................................................ B-1
APPENDIX C – HALL GENERATORS........................................................................................................ C-1
C1.0
GENERAL........................................................................................................................... C-1
C2.0
THEORY OF OPERATION ................................................................................................ C-1
C2.1
Active Area ...................................................................................................................... C-1
C2.2
Orientation....................................................................................................................... C-2
C2.3
Handling .......................................................................................................................... C-3
C2.4
Polarity............................................................................................................................. C-3
C2.5
Lead Configurations ........................................................................................................ C-3
C3.0
HALL GENERATOR GENERIC HOOKUP......................................................................... C-3
C4.0
USING A HALL GENERATOR WITH THE MODEL 421 ................................................... C-4
C5.0
SPECIFICATIONS.............................................................................................................. C-5
C6.0
HALLCAL.EXE PROGRAM................................................................................................ C-8
ii
Lake Shore Model 421 Gaussmeter User’s Manual
LIST OF ILLUSTRATIONS
Figure No.
1-1
2-1
2-2
2-3
3-1
3-2
3-3
3-4
3-5
3-6
5-1
5-2
5-3
5-4
5-5
5-6
5-7
5-8
5-9
5-10
5-11
5-12
5-13
5-14
5-15
6-1
6-2
6-3
6-4
6-5
6-6
C-1
C-2
C-3
C-4
C-5
C-6
C-7
Title
Page
Model 421 Gaussmeter Front Panel............................................................................................. 1-1
Model 421 Rear Panel .................................................................................................................. 2-2
Line Input Assembly ..................................................................................................................... 2-3
Model MCBL-XX User Programmable Cable Assembly............................................................... 2-4
Model 421 Front Panel ................................................................................................................. 3-1
Front Panel Display Definition ...................................................................................................... 3-2
Model 421 AC Frequency Response............................................................................................ 3-4
Maximum Flexible Probe Bend Radius....................................................................................... 3-14
Probe Orientation For Positive Measurement ............................................................................ 3-14
Effect Of Angle On Measurements ............................................................................................. 3-15
Definition of Lake Shore Gamma Probe....................................................................................... 5-4
Definition of Lake Shore Robust (Brass Stem) Transverse Probes ............................................. 5-4
Definition of Lake Shore Transverse Probes................................................................................ 5-5
Definition of Lake Shore Tangential Probe................................................................................... 5-5
Definition of Lake Shore Axial Probes .......................................................................................... 5-6
Definition of Lake Shore Flexible Transverse Probes .................................................................. 5-7
Definition of Lake Shore Flexible Axial Probe .............................................................................. 5-7
Model MH-2.5 Helmholtz Coil ....................................................................................................... 5-8
Model MH-6 Helmholtz Coil .......................................................................................................... 5-9
Model MH-12 Helmholtz Coil ........................................................................................................ 5-9
Lake Shore Reference Magnets ................................................................................................. 5-10
Model 4060 Standard Zero Gauss Chamber.............................................................................. 5-11
Model 4065 Large Zero Gauss Chamber ................................................................................... 5-11
Model RM-1/2 Rack-Mount Kit.................................................................................................... 5-12
Model RM-2 Dual Rack-Mount Shelf .......................................................................................... 5-13
Power Fuse Access ...................................................................................................................... 6-3
PROBE INPUT Connector Details................................................................................................ 6-4
Corrected and Monitor ANALOG OUTPUTS Connector Details.................................................. 6-4
RELAY Terminal Block Details ..................................................................................................... 6-5
SERIAL I/O (DTE) Connector Details ........................................................................................... 6-5
Location Of Operating Software EPROM and Analog Output Jumper......................................... 6-8
Hall Generator Theory ..................................................................................................................C-2
Axial and Transverse Configurations............................................................................................C-2
Typical Hall Generator Hookup.....................................................................................................C-4
Hall Generator Input Impedance...................................................................................................C-4
Axial Hall Generator HGA-3010, HGA-3030, & HGCA-3020 Dimensions ...................................C-5
Transverse Hall Generator HGT-3010, HGT-3030, & HGCT-3020 Dimensions..........................C-5
Transverse Hall Generator HGT-1010 Dimensions......................................................................C-6
iii
Lake Shore Model 421 Gaussmeter User’s Manual
LIST OF TABLES
Table No.
4-1
4-2
4-3
4-4
4-5
B-1
B-2
C-1
C-2
C-3
iv
Title
Page
Serial Interface Specifications .......................................................................................................4-2
Serial Interface Program Control Properties .................................................................................4-5
Visual Basic Serial Interface Program...........................................................................................4-6
Quick Basic Serial Interface Program ...........................................................................................4-7
Serial Interface Commands.........................................................................................................4-10
Conversion from CGS to SI Units ................................................................................................ B-1
Recommended SI Values for Physical Constants........................................................................ B-2
Cryogenic Hall Generator Specifications ..................................................................................... C-5
Axial Hall Generator Specifications.............................................................................................. C-6
Transverse Hall Generator Specifications.................................................................................... C-7
Lake Shore Model 421 Gaussmeter User’s Manual
CHAPTER 1
INTRODUCTION
1.0
GENERAL
This chapter provides an introduction to the Lake Shore Model 421 Gaussmeter. The Model 421
was designed and manufactured in the United States of America by Lake Shore Cryotronics, Inc.
The Model 421 is a highly accurate gaussmeter well suited for field work. It features:
•
•
•
•
•
•
Resolution to 4¾ Digits.
Large Vacuum Fluorescent Display.
Serial Interface.
Analog Voltage Outputs.
Max Hold and Relative Reading.
Alarm with Relay.
If you have just received your new Model 421, please proceed to Chapter 2 and become familiar with
the installation instructions. Complete and detailed instrument and probe operational information is
contained in Chapter 3. Chapter 4 contains details on remote operation using the Serial Interface.
Details on accessories and probes are provided in Chapter 5. Limited service and rear panel connector
definitions are contained in Chapter 6. Appendix A is a glossary of terminology. Appendix B provides
units for magnetic properties. Finally, Appendix C provides information on Hall sensors and the
Hallcal.exe program.
1.1
PRODUCT DESCRIPTION
The Model 421 Hall Effect Gaussmeter is the Lake Shore answer to the dynamic changes in the
permanent magnet industry. Faster, higher resolution, and more repeatable flux density measurements
are being demanded by manufacturing, quality assurance (QA), and research and development (R&D).
The Model 421 is well suited to meet these requirements at an affordable price. The Model 421 is
compatible with the extensive Lake Shore line of probes, or we can design custom probes to meet your
unique needs. As an added advantage, the Model 421 is provided with one probe of customer choice.
421_Front.bmp
Figure 1-1. Model 421 Gaussmeter Front Panel
Introduction
1-1
Lake Shore Model 421 Gaussmeter User’s Manual
Product Description (Continued)
Performance
High-performance instrumentation is no longer the exclusive domain of research laboratories.
Performance requirements are tightening in every magnetic measurement application. In response, the
Model 421 offers improved accuracy, resolution, noise floor, and update rate.
Throughput
Throughput involves much more than update rate of an instrument. Usability of an instrument is just as
important. The Model 421 has a large, bright, vacuum fluorescent display that can be seen easily in any
lighting condition. The display updates quickly for fast feedback of probe or magnet positioning. The
operation is straight forward with display prompts for the user. Max Hold, Alarm, and Sort features are
included to streamline sorting and testing operations.
Automation
The Model 421 has a variety of interface features that are compatible with automated test
configurations. The RS-232C Serial Interface can perform nearly every function of the instrument front
panel. Two analog voltages and an alarm relay facilitate automation without a computer.
Probes
The Model 421 is delivered with one Lake Shore Hall probe of customer choice. A wide range of
additional probes is available including Transverse, Axial, Flexible Transverse, and Gamma Probes™.
Refer to Paragraph 5.2 for a complete list. Lake Shore probes are factory calibrated for accuracy and
interchangeability. Calibration data is loaded into a PROM located in the probe connector so that it does
not have to be entered by the user. Lake Shore can also custom design a probe to meet your specific
application requirements.
Normal Reading
+102.84
G DC
The Model 421 has a 2 line by 20 character vacuum fluorescent display with resolution to 4¾ digits.
The display can accommodate seven measurement ranges from 300.00 mG to 300.00 kG.
Measurements are displayed in either gauss or tesla.
Max Hold On
+102.84
+104.38
G DC
G MAX
The largest field magnitude seen since the last Max Reset is displayed with the Max Hold function. The
maximum value is shown in the lower display while the upper display contains the live reading.
Alarm On
+102.87
G DC
ª
The alarm gives an audible and visual indication of when the field value is selectively outside or inside a
user specified range. An output relay facilitates pass/fail actuation.
Sort On
+2.522 kG DC
** Pass **
ª
The sort function allows the Model 421 to display pass or fail when it is used during repetitive testing.
The live reading is shown in the upper display while the lower display contains the pass/fail message.
1-2
Introduction
Lake Shore Model 421 Gaussmeter User’s Manual
1.2
SPECIFICATIONS
General Measurement
Number Of Inputs: 1
Update Rate: 5 readings per second on display;
up to 18 readings with serial interface
Probe Compatibility: Standard and custom probes,
including Model 420 probes
Probe Features: Linearity Correction, Auto Probe Zero
Measurement Features: Auto Range, Max Hold,
Relative Mode, Filter
Connector: 15 pin D style
DC Measurement
DC Display Resolution: 4¾ digits with filter,
3¾ digits without filter
Range
Resolution w/Filter
Resolution w/out Filter
HST Probe
300 kG
0.01 kG
0.1 kG
30 kG
0.001 kG
0.01 kG
3 kG
0.0001 kG
0.001 kG
300 G
0.01 G
0.1 G
HSE Probe
30 kG
0.001 kG
0.01 kG
3 kG
0.0001 kG
0.001 kG
300 G
0.01 G
0.1 G
30 G
0.001 G
0.01 G
UHS Probe
30 G
0.001 G
0.01 G
3G
0.0001 G
0.001 G
300 mG
0.01 mG
0.1 mG
DC Accuracy: ±0.20% of reading ±0.05% of range
DC Temp. Coefficient: ±0.05% of reading ±0.03% of range/°C
AC RMS Measurement
AC Display Resolution: 3¾ digits
Range
Resolution
HST Probe
300 kG
0.1 kG
30 kG
0.01 kG
3 kG
0.001 kG
300 G
0.1 G
HSE Probe
30 kG
0.01 kG
3 kG
0.001 kG
300 G
0.1 G
30 G
0.01 G
UHS Probe
30 G
0.01 G
3G
0.001 G
300 mG
0.1 mG
AC Frequency Range: 10 – 400 Hz.
AC Accuracy: ±2% of reading (50 – 60 Hz.)
AC Frequency Response: 0 to –3.5% of reading (10 – 400 Hz.)
(All AC specs for sinusoidal input >1% of range. See Figure 3-3.)
Front Panel
Display Type: 2 line by 20 character, vacuum fluorescent
Display Resolution: To ±4¾ digits
Display Update Rate: 5 readings per second
Display Units: Gauss (G), Tesla (T)
Units Multipliers: µ, m, k
Annunciators:
RMS
AC input signal
DC
DC input signal
MAX
Max Hold value
°
Relative reading
R
Remote Operation
ª
Alarm on
Keypad: 12 key membrane
Front Panel Features: Intuitive operation, display prompts, front
panel lockout, brightness control
Introduction
Interfaces
RS-232C Capabilities:
Baud: 300, 1200, 9600
Connector: 9 pin D style, DTE configuration
Software Support: LabView Driver (consult Lake Shore for
availability). Compatible with Model 420 command set.
Alarm
Settings: High/low setpoint, Inside/Outside, Audible, Sort
Actuators: Display annunciator, sort message, beeper, relay
Relay
Number: 1
Contacts: N.O., N.C., and common (C)
Contact Rating: 30 VDC at 2 A
Operation: Follows alarm
Connector: Detachable terminal block
Monitor Analog Output
Configuration: Real-time analog voltage output
Range: ±3 V
Scale: ±3 V = ±FS on selected range
Frequency Response: DC to 400 Hz.
Accuracy: Probe dependent
Minimum Load Resistance: 1 kΩ (short-circuit protected)
Connector: BNC
Corrected Analog Output
Configuration: Voltage output generated by DAC
Range: ±3 V
Scale: ±3 V = ±FS on selected range
Resolution: 1.25 mV
Update Rate: 5 updates per second
Accuracy: ±0.35%
Minimum load resistance: 1 kΩ (short-circuit protected)
Connector: BNC
General
Ambient Temperature: 15 – 35 °C at rated accuracy.
5 – 40 °C with reduced accuracy.
Power Requirement: 100, 120, 220, 240 VAC (+5%, -10%),
50 or 60 Hz, 20 watts
Size: 217 mm W × 90 mm H × 317 mm D, half rack
(8.5 × 3.5 × 12.5 inches)
Weight: 3 kilograms (6.6 pounds)
Approval: CE Mark
Ordering Information
Part Number
Instrument
421
Description
Model 421 Gaussmeter plus one probe
(Specify line voltage and probe model number)
Accessories Included:
106-741
Terminal block for relay outputs
115-006
Detachable line cord (U.S.)
4060
Zero Gauss Chamber
MAN-421
Model 421 Gaussmeter User’s Manual
Accessories Available:
RM-1/2
Rack mount kit for one ½ rack gaussmeter
in 483 mm (19 inch) rack
RM-2
Rack mount kit for two ½ rack gaussmeters
in 483 mm (19 inch) rack
MCBL-6
User programmable cable with PROM (6 feet)
MCBL-20
User programmable cable with PROM (20 feet)
MPEC-10
Probe extension cable with EEPROM (10 feet)
MPEC-25
Probe extension cable with EEPROM (25 feet)
MPEC-50
Probe extension cable with EEPROM (50 feet)
MPEC-100
Probe extension cable with EEPROM (100 feet)
(Extension cables must be matched to probes)
One Probe Included (refer to Paragraph 5.2 for details)
Custom Probes Available (consult Lake Shore for details)
Specifications subject to change without notice.
1-3
Lake Shore Model 421 Gaussmeter User’s Manual
1.3
SAFETY SUMMARY
Observe the following general safety precautions during all phases of operation, service, and repair of
this instrument. Failure to comply with these precautions or with specific warnings elsewhere in this
manual violates safety standards of design, manufacture, and intended use of the instrument. Lake
Shore Cryotronics, Inc. assumes no liability for customer failure to comply with these requirements.
The Model 421 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.
• Temperature: 5 – 40 °C.
• Maximum Relative Humidity: 80% for temperatures up to 31 °C decreasing linearly to 50% at 40 °C.
• Power supply voltage fluctuations not to exceed ±10% of the nominal voltage.
Ground The Instrument
To minimize shock hazard, connect instrument chassis and cabinet to an electrical ground. The
instrument is equipped with a three-conductor AC power cable; either plug it into an approved threecontact outlet or use a three-contact adapter with the grounding wire (green) firmly connected to a
ground (safety ground) at the power outlet. The power jack and mating plug of the power cable meet
Underwriters Laboratories (UL) and International Electrotechnical Commission (IEC) safety standards.
Do Not Operate In An Explosive Atmosphere
Do not operate the instrument in the presence of flammable gases or fumes. It is a safety hazard.
Keep Away From Live Circuits Inside the Instrument
Operating personnel must not remove instrument covers. Refer component replacement and internal
adjustments to qualified maintenance personnel. Do not replace components with power cable
connected. To avoid injuries, always disconnect power and discharge circuits before touching them.
Do Not Substitute Parts Or Modify Instrument
Because of the danger of introducing additional hazards, do not install substitute parts or perform any
unauthorized modification to the instrument. Return the instrument to an authorized Lake Shore
Cryotronics representative for service and repair to ensure that safety features are maintained.
Do Not Place Conductive Probes Against Exposed Electrical Circuits
Some gaussmeter probes are equipped with conductive sheaths. Keep these probes away from live
electrical circuits.
1.4
1-4
SAFETY SYMBOLS
Introduction
Lake Shore Model 421 Gaussmeter User’s Manual
CHAPTER 2
INSTALLATION
2.0
GENERAL
This chapter provides general installation instructions for the Model 421 Gaussmeter. Inspection and
unpacking instructions are provided in Paragraph 2.1. Repackaging for shipment instructions are
provided in Paragraph 2.2. An definition of rear panel controls is provided in Paragraph 2.3. Finally,
an initial setup and system checkout procedure is provided in Paragraph 2.4.
2.1
INSPECTION AND UNPACKING
Inspect shipping containers for external damage. All claims for damage (apparent or concealed) or
partial loss of shipment must be made in writing to Lake Shore within five (5) days from receipt of
goods. If damage or loss is apparent, please notify the shipping agent immediately.
Open the shipping containers. A packing list is included with the system to simplify checking that the
instrument, probe(s), accessories, and manual were received. Please use the packing list and the
spaces provided to check off each item as the instrument is unpacked. Inspect for damage. Be sure to
inventory all components supplied before discarding any shipping materials. If there is damage to the
instrument in transit, be sure to file proper claims promptly with the carrier and insurance company.
Please advise Lake Shore Cryotronics of such filings. In case of parts or accessory shortages, advise
Lake Shore immediately. Lake Shore cannot be responsible for any missing parts unless notified within
60 days of shipment. The standard Lake Shore Cryotronics, Inc. Warranty is included on the A Page
(immediately behind the title page) of this manual.
2.2
REPACKAGING FOR SHIPMENT
If it is necessary to return the Model 421, probe(s), or accessories for repair or replacement, a Return
Goods Authorization (RGA) number must be obtained from a factory representative before returning the
instrument to our service department. When returning an instrument for service, the following
information must be provided before Lake Shore can attempt any repair.
A. Instrument model and serial number.
B. User’s name, company, address, and phone number.
C. Malfunction symptoms.
D. Description of system.
E. Returned Goods Authorization (RGA) number.
If possible, the original packing material should be retained for reshipment. If not available, consult Lake
Shore for shipping and packing instructions.
Because of their fragility, Lake Shore probes are shipped in special cardboard and foam boxes. These
boxes should be retained for storage of probes while the gaussmeter is not in use. The same box can
be used to return probes to Lake Shore for recalibration or repair.
Installation
2-1
Lake Shore Model 421 Gaussmeter User’s Manual
2.3
REAR PANEL DEFINITION
This paragraph provides a description of the Model 421 rear panel connections. The rear panel consists
of the line input assembly, Serial I/O Connector, Probe Input Connector, Corrected and Monitor Analog
Output BNCs, and Relay Terminal Block. This paragraph is provided for information only. Please read
the entire paragraph then proceed to Paragraph 2.8 for the initial setup and system checkout
procedure. Rear panel connector pin-out details are provided in Chapter 6 – Service.
CAUTION: Verify AC Line Voltage shown in the fuse holder window is appropriate for the intended AC
power input. Also remove and verify the proper fuse is installed before plugging in and
turning on the instrument.
CAUTION: Always turn off the instrument before making any rear panel connections. This is especially
critical when making probe to instrument connections.
421_Rear.bmp
Description
Pin Definition
Paragraph 2.4
Figure 2-2
Paragraph 4.1.1
Figure 6-5
c
Line Input Assembly
d
SERIAL I/O 9 pin D-Style Connector
e
PROBE INPUT 15 pin D-Style Connector
Paragraph 2.5
Figure 6-2
f
Monitor ANALOG OUTPUT BNC
Paragraph 2.6
Figure 6-3
g
Corrected ANALOG OUTPUT BNC
Paragraph 2.6
Figure 6-3
h
RELAY Terminal Block
Paragraph 2.7
Figure 6-4
Figure 2-1. Model 421 Rear Panel
2-2
Installation
Lake Shore Model 421 Gaussmeter User’s Manual
2.4
LINE INPUT ASSEMBLY
This section covers line voltage and fuse verification in Paragraph 2.4.1, power cord in Paragraph 2.4.2,
and power switch in Paragraph 2.4.3.
2.4.1
Line Voltage and Fuse Verification
To verify proper line voltage selection look at the indicator in the window on the fuse drawer of the
line input assembly. Line voltage should be in the range shown in the specifications listed on the back
of the instrument. See Figure 2-2. If not, change the line voltage selector per instructions in
Paragraph 6.3. The fuse must be removed to verify its value, refer to the procedure in Paragraph 6.4.
Use slow-blow fuses of the value specified on back of the instrument.
2.4.2
Power Cord
The Model 421 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.
2.4.3
Power Switch
The power switch turns the instrument On and Off and is located in the line input assembly on the
instrument rear. When l is raised, the instrument is On. When O is raised, the instrument is Off.
Line Cord
Input
Power Switch
O = Off, l = On
Fuse
Drawer
120
100/120/220/240 V
–10% +6% Voltage 100/120V 0.5 A T 250V 0.25×1.25"
50-60 Hz 40 VA MAX 220/240V 0.25 A T 250V 5×20mm
F-421-2-2.eps
Figure 2-2. Line Input Assembly
2.5
PROBE INPUT CONNECTION
WARNING: Some probes used with the gaussmeter have conductive parts. Never probe near
exposed live voltage. Personal injury and damage to the instrument may result.
CAUTION: Always turn off the instrument before making any rear panel Probe Input connections.
Lake Shore probes plug into the 15 pin D-style connector on the Model 421 rear panel. Turn the
instrument off before attaching a probe. See Figure 8-3 for pin definitions.
When power is turned on, the instrument reads parameters from probe memory. The probe is ready to
use. No parameters need to be entered into the Model 421. However, the Zero Probe function should
be performed the first time a probe is used with the instrument and periodically during use.
Installation
2-3
Lake Shore Model 421 Gaussmeter User’s Manual
2.5.1
Attachment To A Hall Generator
The Model MCBL-XX has a 15 pin D-Style connector on one end for direct attachment to the
PROBE INPUT on the back panel of the Model 421 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 MCBL-6 is 2 meters (6 feet) and the MCLB-20 is 6 meters (20 feet).
Current to
Sensor
Hall Voltage
from Sensor
{
{
Green Wire (–)
Red Wire (+)
6 Foot Cable to
Gaussmeter
Blue Wire (+)
Yellow Wire (–)
F-421-2-3.eps
Figure 2-3. Model MCBL-XX User Programmable Cable Accessory
CAUTION: The Hall Generator should be isolated from all line voltages (or voltages referenced to
earth ground). If not, damage to the Model 421 Gaussmeter is almost a certainty.
Refer to Appendix C for a complete list of compatible Hall generators manufactured by Lake Shore.
Once connections are made, refer to Paragraph C6.0 for instructions on using the Hallcall.exe
program to store probe parameters in the internal EPROM.
2.6
CORRECTED AND MONITOR ANALOG OUTPUTS
Analog outputs are available on two Bayonet Nut Connectors (BNCs). The signal is on the center
conductor while the outer casing is for ground. Both outputs may be used simultaneously. The
corrected output is not a real-time signal, but is updated at the same rate as the display. The range of
the corrected output is ±3 volts equals ± full scale for the range. The monitor output is a live analog
signal proportional to the magnetic flux density waveform. Refer to Paragraph 3.10 for further
operational information.
2.7
RELAY TERMINAL BLOCK
The Model 421 has a single relay output that follows the alarm state. The relay outputs have a
detachable 3-pin terminal block connector. The connector (included with the Model 421) can be
removed from its socket for convenient installation of wires. The connector manufacturer indicates that
up to 12 AWG stranded copper wire can be used with the connector.
CAUTION: Always turn off the instrument before making any rear panel terminal block connections.
Terminal
Description
1
Normally Closed (NC)
2
Common (C)
3
Normally Open (NO)
The terminal block has normally open (NO), normally closed (NC), and common (C) contacts in a
Single Pole Double Throw (SPDT) configuration. The instrument provides no power through the relay; it
opens and closes as switches relative to the alarm state. The contacts are rated at 30 VDC at 2 A.
Refer to Paragraph 3.9 for alarm and relay operation.
2-4
Installation
Lake Shore Model 421 Gaussmeter User’s Manual
2.8
INITIAL SETUP AND SYSTEM CHECKOUT PROCEDURE
The following procedure is an initial instrument setup and checkout procedure. The intent of this
procedure is to verify basic operation of the unit before beginning use for measurements.
CAUTION: Check power source for proper voltage before connecting the line cord to the
Model 421. Also check the power setting on the window in the fuse drawer.
Damage to unit may occur if connected to improper voltage.
1. Check power source for proper voltage. The Model 421 operates with 100, 120, 220, or 240
(+5%, –10%) AC input voltage.
2. Check window in fuse drawer for proper voltage setting. If incorrect, refer to Paragraph 5.2.
3. Ensure the power switch is in the off (O) position.
CAUTION: The probe must be connected to the rear of the unit before applying power to the
gaussmeter. Damage to the probe may occur if connected with power on.
4. Plug in the probe connector to PROBE INPUT. Use thumbscrews to tighten connector to unit.
5. Ensure any other rear panel connections (SERIAL I/O or ANALOG OUTPUTS) are connected
before applying power to the unit.
6. Plug line cord into receptacle.
7. Turn the power switch to the on (l) position. The front panel display should turn on and the following
message briefly appear.
Lake Shore 421
Field Monitor
8. The normal gaussmeter display will now appear. A typical display is illustrated below.
+ 0.001
G DC
NOTE: For best results, the instrument and probe should warm up for at least 5 minutes before
zeroing the probe, and at least 30 minutes for rated accuracy. The probe and the zero
gauss chamber should be at the same temperature.
NOTE: Some Lake Shore probes come with a clear plastic sleeve to protect the probe tip when not
in use. The sleeve slides up and down the probe cable. To place the probe in the zero
gauss chamber, slide the protective sleeve back, exposing the probe tip, before placing the
tip in the chamber.
9. If so equipped, slide the clear plastic sleeve back, exposing the tip of the probe. Place the probe in
the zero gauss chamber and press the front panel Zero Probe key. The display below appears.
Press Enter With
Probe At Zero
Installation
2-5
Lake Shore Model 421 Gaussmeter User’s Manual
INITIAL SETUP AND SYSTEM CHECKOUT PROCEDURE (Continued)
10. Press the Enter key. The *CALIBRATING* message will briefly be displayed, followed by a return
to the normal display.
NOTE: If the unit has performed well to this point, the unit is functioning properly. If you have a
reference magnet available, you can continue with the test using the magnet to verify the
accuracy of the Model 421.
11. If continuing the procedure with a reference magnet, ensure the probe can accommodate the
range of the magnet. Use the Range key to select the proper range. Set the display for DC.
Finally, since orientation of the probe is very selective, press the Max Hold key. This will capture
the highest reading (normally the reference magnet calibration value).
CAUTION: Care must be exercised when handling the probe. The tip of the probe is very
fragile. Any excess force may break the probe.
NOTE: Probe readings are dependent upon the angle of the tip in relation to the magnetic field.
This and other effects on probe operation are explained in Paragraph 3.16.
12. Carefully place probe into reference magnet. You may have to hunt around a bit for the maximum
reading. For this example, we are using a 999 ±1% Gauss Reference Magnet. Our reading
appeared as follows:
+ 0.9720 kG DC
0.9950 kG MAX
On the top line, the current reading is +0.9720 kG DC. On the bottom line, the maximum reading
captured was 0.9950 kG, which is within the tolerance of the reference magnet. The top line will
keep changing as the probe moves, but the bottom will remain fixed on the highest reading. To
recapture a new maximum value, press the Max Reset key.
Once this abbreviated checkout procedure is successfully completed, the unit is ready for normal
operation. Please proceed to Chapter 3 for further operational information.
2-6
Installation
Lake Shore Model 421 Gaussmeter User’s Manual
CHAPTER 3
OPERATION
3.0
GENERAL
This chapter describes Model 421 Gaussmeter operation. The front panel controls are described in
Paragraph 3.1. Paragraphs 3.2 thru 3.14 describe the various front panel functions in detail. Model 421
default settings are defined in Paragraph 3.15. Finally, Paragraph 3.16 provides probe handling
considerations. Refer to Chapter 4 for detailed information on remote operation (serial interface).
3.1
DEFINITION OF FRONT PANEL CONTROLS
This paragraph provides a description of the front panel controls on the Model 421.
3.1.1
Front Panel Keypad
The keys on the front panel are defined as follows. Note the following are abbreviated descriptions of
each key. A more detailed description of each function is provided in subsequent paragraphs.
Max Reset
Works with the Max Hold function. Clears Max reading back to current reading.
Press and hold to reset parameters to default values. This key also acts as an
escape key during numeric entry.
Max Hold
Turns the Max Hold feature on and off. Use Max Reset key to clear reading.
Press and hold to lock keypad.
Zero Probe
Used to zero or null effects of ambient low level fields from the probe.
Range
Selects a manual field measurement range or Autorange. Available ranges are
dependent on which probe is installed.
AC/DC
Selects periodic AC (RMS) or static (DC) magnetic fields. Press and hold to turn
Filter on or off.
421_Front.bmp
Figure 3-1. Model 421 Front Panel
Operation
3-1
Lake Shore Model 421 Gaussmeter User’s Manual
Front Panel Keypad Definitions (Continued)
3.1.2
Gauss/Tesla
Changes display units from gauss to tesla. Gauss (G) is used in the cgs system, tesla
(T) is used in the SI system, where 1 T = 104 G.
Relative
Used to capture a relative setpoint, the display shows the positive or negative
deviation from that setpoint. Press and hold to adjust the brightness of the vacuum
florescent display.
Interface
The Serial Interface baud rate of the Model 421 transmissions may be changed from
300, 1200, or 9600. Press and hold to initiate Fast Data Mode from the front panel.
Alarm
Turns alarm feature on or off and allows entry of alarm setpoints. Press and hold to
turn the audible beeper on or off, select the alarm to operate inside or outside the
setpoint range, and turn the sort feature on or off.
s
Toggles between various settings shown in the display and increments a numerical
display.
t
Toggles between various settings shown in the display and decrements a numerical
display.
Enter
Accepts changes to parameter setting.
Front Panel Display
In normal operation, the 2 row by 20 character vacuum fluorescent display provides current magnetic
readings on the top row and special information or readings on the bottom row. Other information is
displayed when using the various functions on the keypad. Each character is comprised of a 5 by 7
dot matrix. See Figure 3-2. To change the display brightness, prefer to Paragraph 3.14.
Probe Orientation
(DC Only)
Current Reading
Units:
kG
G
mG
T
mT
µT
DC
RMS
Relative
On
Alarm
On
Lower row used for Max Hold (MAX) (shown above) and Relative
Setpoint (SP) readings. Also used for various on/off messages.
C-421-3-2.eps
Figure 3-2. Front Panel Display Definition
3-2
Operation
Lake Shore Model 421 Gaussmeter User’s Manual
3.1.3
General Keypad Operation
Human interface with the instrument is provided by the 12 buttons that comprise the front panel
keypad. Most operations can be performed through the front-panel keypad and monitored by
watching the front panel display.
NOTE: Timeout is treated as escape, i.e., any changes made will not be retained if the display
times out and returns to the main display.
There are five basic keypad operations:
1. Direct Operation: The following key functions occurs upon pressing the key: Max Reset,
Max Hold, Zero Probe, AC/DC, Gauss/Tesla, and Relative.
2. Direct Operation After Press And Hold: The following key functions occurs immediately after
pressing and holding a key: Set Defaults, Lock Keypad, and Fast Data Mode.
3. Setting Selection: The following functions will display a selection of settings immediately upon
pressing a key: Range, Baud Rate, and Alarm On/Off. The arrow keys are active when you see
the “°®” symbol on the display. Pressing the Enter key will enter parameter changes and return
you to the main screen.
4. Setting Selection After Press And Hold: The following functions will display a selection of
settings after pressing and holding a key: Filter, Brightness, Audible Alarm, Alarm
Inside/Outside, and Sort. The arrow keys are active when you see the “°®” symbol on the
display. Pressing the Enter key will enter parameter changes and return you to the main screen.
5. Numeric Data Entry: The high and low alarm setpoints require numeric data entry. Numbers can
be entered with up to 5 digits of resolution in any field range available for the probe being used.
To begin number entry look at the range and resolution of the present parameter value. If it is too
small to accommodate the new value, or too large to allow appropriate resolution, change the
setting range by pressing the Range key. Pressing the Range key will cycle through all available
setting ranges and zero the setting value.
The most significant digit of the entry value will blink to indicate that digit can be changed. Use
the s or t keys to change that digit to the desired value. Digits should be set to zero if not used.
Press the Enter key to advance to the next digit. Continue until all digits are set. When the Enter
key is pressed on the last digit the setting value will be stored. If a mistake is made press the
Range key to select a new range and start over or press Max Reset to escape out of the setting
function.
3.2
GAUSS/TESLA
The Model 421 displays magnetic field values in gauss (G) or tesla (T). Pressing the Gauss/Tesla key
toggles the display between the two units. The relation between gauss and tesla is 1 G = 0.0001 T, or
1 T = 10,000 G. When the field units are changed, relative and alarm setpoints are converted to the
new units with no interruption in operation. The Corrected and Monitor Analog Outputs are not affected
by a change in units.
When tesla is selected, the Model 421 displays AC or DC field values followed by T for tesla, mT for
millitesla, or µT for microtesla. Field values available over the Serial Interface are formatted accordingly.
When gauss is selected, the Model 421 displays AC or DC field values followed by kG for kilogauss,
G for gauss, or mG for milligauss. The field value available over the Serial Interface is formatted
accordingly.
Operation
3-3
Lake Shore Model 421 Gaussmeter User’s Manual
3.3
AC/DC
Pressing the AC/DC key toggles between AC and DC measurements. The annunciator immediately
changes from DC to RMS, as applicable. However, one update cycle is required for a new display value.
In DC operation, the display shows the DC field at the probe with sign (orientation) followed by the
appropriate field units and the letters DC. The DC value is available over the Serial Interface and both
Analog Outputs. The resolution of DC readings is 3¾ digits when the filter feature is turn off and
4¾ digits when the filter is turned on.
In AC operation, the RMS readings will meet specified accuracy from 10 to 400 Hz. The AC RMS value
is defined as the square root of the average of the square of the value of the function taken throughout
one period. Frequency response and noise dominate the error present in AC mode. The Model 421 has
a predictable frequency response which is illustrated in Figure 3-3.
The RMS value is available over the Serial Interface. A DC voltage representation of the RMS display
reading is available from the Corrected Analog Output, while a true analog waveform is available from
the Monitor Analog Output. (In fact, the Monitor Analog Output is not affected by the selection of AC
or DC.) The resolution of AC RMS readings is fixed at 3¾ digits.
P-421-3-3.bmp
Figure 3-3. Model 421 AC Frequency Response
3.4
DISPLAY FILTER
The display filter function is used to quiet the display and make it more readable when the probe is
exposed to a noisy field. Care should be taken when using the filter on changing fields because it may
level off peaks and slow the response of the instrument. The filter also acts to quiet noise within the
instrument, making an additional digit of usable resolution available with the filter on in DC. The filter
function makes a linear average of 8 readings and settles in approximately 2 seconds.
To turn on the display filter, press and hold the AC/DC key for 5 seconds. The following display will
appear.
Select With °®
Filter
On ¡Off
Use the s or t keys to toggle between On and Off. Press the Enter key to accept the new setting.
3-4
Operation
Lake Shore Model 421 Gaussmeter User’s Manual
3.5
MANUAL RANGE AND AUTO RANGE
The Model 421 is capable of reading each of the Lake Shore probe types: High Stability (HST),
High Sensitivity (HSE), or Ultra-High Sensitivity (UHS). The three probes permit the Model 421 to be
used with ranges of 300 mG to 300 kG. The full-scale ranges for each probe type, along with the
display resolution, are shown as follows.
DC Resolution
with Filter
DC Resolution
without Filter
HST Probe
300 kG
30 kG
3 kG
300 G
0.01 kG
0.001 kG
0.0001 kG
0.01 G
0.1 kG
0.01 kG
0.001 kG
0.1 G
0.1 kG
0.01 kG
0.001 kG
0.1 G
HSE Probe
30 kG
3 kG
300 G
30 G
0.001 kG
0.0001 kG
0.01 G
0.001 G
0.01 kG
0.001 kG
0.1 G
0.01 G
0.01 kG
0.001 kG
0.1 G
0.01 G
UHS Probe
30 G
3G
300 mG
0.001 G
0.0001 G
0.01 mG
0.01 G
0.001 G
0.1 mG
0.01 G
0.001 G
0.1 mG
Range
AC RMS
Resolution
For manual ranging, pressing the Range key and the following display will appear.
Select With °®
+/- 3.000 kG
Use the s or t keys to toggle through the allowable full scale ranges for the probe installed. Press the
Enter key to accept the new setting.
In Auto Range mode, the Model 421 selects the range with the best resolution for the field being
measured. It can take up to 2 seconds for Auto Range to work, so manual ranging may be better in
some conditions. Press the Range key.
Select With °®
Auto Range
Use the s or t keys to toggle through the allowable full scale ranges until Auto Range is displayed.
Press the Enter key to accept the new setting.
Auto Range should not be used with Max Hold operation or when alarms are active. Also, Auto Range
should not be used when measuring small fields in a large background field, i.e., measuring a small DC
field in presence of a large AC field, or measuring a small AC field in the presence of a large DC field.
Operation
3-5
Lake Shore Model 421 Gaussmeter User’s Manual
3.6
ZERO PROBE
The zero probe function is used to null (cancel) out the zero offset of the probe or small magnetic fields.
It is normally used in conjunction with the zero gauss chamber, but may also be used with an open
probe (registering the local Earth magnetic field). Users wishing to cancel large magnetic fields should
use the Relative function.
NOTE: For best results, the instrument and probe should warm up for at least 5 minutes
before zeroing the probe, and at least 30 minutes for rated accuracy. The probe
and the zero gauss chamber should be at the same temperature.
To zero the probe in the zero gauss chamber, first allow the temperature of the probe and chamber to
be approximately equal. (A large temperature discrepancy affects the quality of the calibration.)
Carefully place the probe tip into the chamber. Orientation of the probe is not critical. Once inserted,
press the Zero Probe key and observe the following display.
Press Again With
Probe At Zero
Press the Zero Probe key. The *CALIBRATING* message is briefly displayed, followed by a return to
the normal display. The probe is now calibrated. For best results, periodic zeroing of the probe is
recommended.
3.7
MAX HOLD AND MAX RESET
The Max Hold function displays the largest field magnitude measured since the last Max Reset. When
the Max Hold key is pressed, the maximum value is shown in lower line of the display while the upper
line contains the current field reading.
+2.483
2.544
kG DC
kG MAX
The Max Reset key clears the hold value. The hold value is also reset upon power up or when
changing from AC or DC. Max Hold may also be used in conjunction with the Relative display
(refer to Paragraph 3.8).
In DC operation, the Max Hold feature holds the field reading that is largest in magnitude. This is
intended to monitor slowly changing signals. A field change not visible on the display can not be
recorded in DC Max Hold. The display shows only the magnitude of the largest reading.
In AC RMS operation, the maximum RMS value is held.
3-6
Operation
Lake Shore Model 421 Gaussmeter User’s Manual
3.8
RELATIVE
The relative function lets the user see small variations in larger fields. The setpoint (or center) of the
relative reading is set when pressing the Relative key. This captures the current reading and effectively
nulls the present field.
+1.420 kG DC
Relative On
Once the Relative key is pressed, the Relative On message is briefly shown on the lower line of the
display. This is followed with the selected setpoint (SP) being displayed on the lower line and the
current plus or minus deviation from that setpoint on the upper line. A small delta (°) is also displayed
to signify the relative display.
+0.000
+1.420
kG DC
kG SP
°
The relative feature also interacts with other features. When Relative and Max Hold functions are used
at the same time, the relative reading is still in the top display with proper annunciators, but the bottom
display shows the relative maximum instead of the relative setpoint.
+0.002
+0.010
kG DC
kG MAX
°
Pressing Max Hold again turns off the maximum hold function, returning the relative setpoint to the
display. Pressing the Relative key turns off the relative function. The Relative Off message is briefly
displayed.
3.9
ALARM AND RELAY
The alarm feature can be easily configured to perform several different tasks including error detection
and limit testing. The most powerful application is manual magnet testing and sorting. A display
annunciator, message display, beeper, and relay are all available to indicate an active alarm state. This
section describes all of the parameters available for the alarm feature then gives examples to illustrate
operation under different conditions.
When the alarm feature is on the alarm annunciator (ª) will appear in the top display. If there is an
alarm condition the annunciator will flash to indicate the alarm is active. If there is not an alarm
condition the annunciator will remain steady to indicate the alarm is in its normal state. Beeper and
relay operation follow the alarm condition in a similar way when they are in use. The alarm function is
non-latching so no action is required to reset the alarm. The alarm resets automatically when the alarm
condition is no longer present.
To turn the alarm feature on press the Alarm key and the following display will appear.
Select With
Alarm
¡On
°®
Off
Use the s or t keys to select between Alarm On and Off and press Enter to accept the new setting.
Operation
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Lake Shore Model 421 Gaussmeter User’s Manual
ALARM AND RELAY (Continued)
When the alarm is turned on, two additional setting screens will appear for high and low alarm
setpoints. These values establish the limit for an error condition or the pass/fail limits for magnet testing.
The values can be entered with the display resolution on any range available for the probe being used.
The setpoint values are entered as positive numbers since the alarm feature uses the absolute
(unsigned) value of field for comparison. Operation of the alarm setpoints is best understood when
viewing the alarm inside/outside parameter examples below.
To enter the high alarm setpoint continue from Alarm On/Off or press the Alarm key and press the
Enter key until the following display appears.
Enter High Alarm
1.5000 kG
The high alarm setpoint requires numeric data entry. Numbers can be entered with up to 5 digits of
resolution in any field range available for the probe being used.
To begin number entry look at the range and resolution of the present parameter value. If it is too small
to accommodate the new value, or too large to allow appropriate resolution, change the setting range
by pressing the Range key. Pressing the Range key will cycle through all available setting ranges and
zero the setting value.
The most significant digit of the entry value will blink to indicate that digit can be changed. Use the
s or t keys to change that digit to the desired value. Digits should be set to zero if not used. Press the
Enter key to advance to the next digit. Continue until all digits are set. When the Enter key is pressed
on the last digit the setting value will be stored. If a mistake is made press the Range key to select a
new range and start over or press Max Reset to escape out of the setting function.
After entering the desired high alarm point, press Enter to accept the new value. The display proceeds
to the Low Alarm Point as follows:
Enter Low Alarm
0.5000 kG
The low alarm setpoint requires numeric data entry. Numbers can be entered with up to 5 digits of
resolution in any field range available for the probe being used.
To begin number entry look at the range and resolution of the present parameter value. If it is too small
to accommodate the new value, or too large to allow appropriate resolution, change the setting range
by pressing the Range key. Pressing the Range key will cycle through all available setting ranges and
zero the setting value.
The most significant digit of the entry value will blink to indicate that digit can be changed. Use the
s or t keys to change that digit to the desired value. Digits should be set to zero if not used. Press the
Enter key to advance to the next digit. Continue until all digits are set. When the Enter key is pressed
on the last digit the setting value will be stored. If a mistake is made press the Range key to select a
new range and start over or press Max Reset to escape out of the setting function.
The alarm setpoints are absolute (unsigned) i.e., only the magnitude of the field reading is used.
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Operation
Lake Shore Model 421 Gaussmeter User’s Manual
ALARM AND RELAY (Continued)
The Model 421 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. To turn the beeper on or off, press and hold the Alarm key until
the following message appears.
Select With
Audible ¡On
°®
Off
Use the s or t keys to cycle between audible alarm On or Off. Press Enter to accept the new value.
When the alarm feature is used to detect an error condition an active alarm state is expected when the
field reading is higher than the high alarm setpoint or below the low alarm setpoint. This operation is
achieved by setting the inside/outside parameter to outside. It is called outside because the alarm is
active when the reading is outside the range of the two setpoints. During magnet testing or sorting it is
often desirable to have the alarm active when the field reading is inside or between the two setpoints.
This operation is achieved by setting the inside/outside parameter to inside. (see examples below)
To select inside/outside alarm operation, continue from Audible On/Off screen or press and hold the
Alarm key until the Audible setting window appears, then press Enter until the following message
appears.
Select With
Alarm
¡In
°®
Out
Use the s or t keys to cycle between the alarm triggered inside (In) or outside (Out) alarm setpoints.
Press Enter to accept the changes.
Model 421 can be configured to display pass or fail when it is used during repetitive magnet testing or
sorting operations. The sort message can be turned on or off as necessary and does not affect other
operations of the alarm feature. When sort is turned on the lower display line will show:
Fail Low
Field below low alarm setpoint.
** Pass **
Field between the two alarm setpoints.
Fail High
Field above high alarm setpoint.
The message will use the lower display line during max hold or relative measurements. The live reading
will be replaced during max hold operation and the relative setpoint will be replaced during relative
operation.
To enable the sort message continue from Inside/Outside or press and hold the Alarm key until the
Audible setting window appears then press the Enter key until the following message appears.
Select With
Sort
¡On
°®
Off
Use the s or t keys to select between Sort On and Off, then press Enter to accept the new setting.
Operation
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Lake Shore Model 421 Gaussmeter User’s Manual
ALARM AND RELAY (Continued)
The Model 421 has a single relay that is associated with alarm operation. The relay changes to its
active state when the alarm is active and remains in its normal state when the alarm is not active. Relay
terminals are located in a detachable terminal block on the instrument rear panel as described in
Paragraph 2.7.
The following example details operation with the Alarm Outside setting. For example, if the reading is
to be centered on 1 kG, with the high alarm point at 1.5 kG and the low alarm point at 0.5 kG, the
following diagram illustrates when the alarm would be active or normal.
Alarm
On
–3 kG
–2 kG
Alarm
Off
Alarm
On
Alarm
Off
–1 kG
0 kG
+1 kG
Example of operation
with alarm triggered by
readings OUTSIDE
user defined setpoints.
Alarm
On
+2 kG
+3 kG
Low Alarm
Point
High Alarm Point
The following example details how the alarm operates in the Alarm Inside setting. The alarm inside
setup is useful in situations where the user is looking for an indication of a good reading, such as
incoming inspections. For example, you may be sorting a number of 1 kG magnets. The magnets have
an acceptable tolerance of ±0.25 kG. With the high alarm point set to 1.25 kG and the low alarm point
at 0.75 kG, the following diagram illustrates when the alarm would be active or normal.
Alarm
Off
–3 kG
–2 kG
Example of operation
with alarm triggered by
readings INSIDE user
defined setpoints.
Alarm
On
Alarm
Off
Alarm
On
–1 kG
0 kG
+1 kG
Alarm
Off
+2 kG
+3 kG
Low Alarm
Point
High Alarm Point
3.10 ANALOG OUTPUTS
There are two analog outputs available on the rear panel of the Model 421. They are the Corrected and
Monitor Analog Outputs. Both outputs use BNC connectors with the center conductor carrying the
signal and the outer portion the ground.
The Corrected Analog Output is a DC value proportional to the displayed field. The displayed field
reading is corrected for probe nonlinearity and zero offset. This output is not a real time signal, but is
updated at the same rate as the display. The range of the Corrected output is ±3 volts equals ± full
scale for the selected range.
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Operation
Lake Shore Model 421 Gaussmeter User’s Manual
ANALOG OUTPUTS (Continued)
For the example below, the 3 kG range was selected.
Display
Reading
–3 kG
–2 kG
–1 kG
Output
Voltage
–3 V
–2 V
–1 V
0 kG
+1 kG
+2 kG
+3 kG
+1 V
+2 V
+3 V
0V
The Monitor Analog Output is a real-time analog signal proportional to the magnetic field. The scale of
the Monitor Analog Output is ±3 volts for full scale of selected range. The Monitor Analog Output is not
as accurate as the Corrected Monitor Output, but it has a full DC to 400 Hz. bandwidth.
3.11 INTERFACE PARAMETERS
If using the Serial Interface, the user must set the Baud rate. Baud is the only interface parameter that
can be changed by the user. Refer to Chapter 4 for details on computer interface operation.
Pressing the Interface key brings up the following display.
Select With
Baud ¡3 12
°®
96
Press the s or t key to cycle through the choices of 300, 1200, or 9600 Baud. Press the Enter key to
accept the selected Baud rate.
3.12 FAST DATA MODE
In normal operation, the instrument updates the display, computer interface, and the corrected analog
output at a rate of 5 readings per second. A Fast Data Mode has been included to increase the data
rate when operating with the Serial Interface. While the corrected analog output update rate does
correspond to the Fast Data Mode, the front panel display will not operate in this mode. When the
Model 421 is operating in Fast Data Mode, the user will see the following front panel display:
Fast Data Mode
There are two methods for placing the instrument in Fast Data Mode: from the front panel or via the
Serial Interface. From the front panel, press and hold the Interface key. The Fast Data Mode display
(shown above) will appear. Press any other key to return the instrument to normal operation.
From the Serial Interface, use the following command:
FAST 1
To leave fast data mode, use the following command:
FAST 0
To query the status of Fast Data Mode, use the following command:
FAST?
In response to the query, a 0 will be returned if off and a 1 will be returned if on.
NOTE: When Fast Data Mode is activated, the following Model 421 functions are disabled:
Relative, Max Hold, Alarms, and Autorange.
Use the normal interface command to query the field measurement data. Without display overhead, the
instrument can take a maximum of 18 readings per second at 9600 Baud. When using the Serial
Interface, never try to read faster than 18 readings a second.
Operation
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Lake Shore Model 421 Gaussmeter User’s Manual
3.13 LOCKING AND UNLOCKING THE KEYPAD
The Model 421 front panel keypad may be locked, preventing inadvertent changes to the settings. To
lock the keypad, press and hold the Max Hold key (≈10 seconds) until the following display is seen.
Lock Keypad
The keypad is now locked. Any attempt to change settings causes the *LOCKED* message to briefly be
displayed on the top line of the display. The only exception is the user may still use the Alarm key to
turn off an alarm even though the keypad is locked.
To unlock the keypad, again press and hold the Max Hold key until the following display is seen.
Unlock Keypad
The keypad is now unlocked and the display will revert to the normal display.
3.14 DISPLAY BRIGHTNESS
The overall brightness of the front panel vacuum florescent display is user controllable. Press and hold
the Relative key until you see the following display.
Select With °®
Brightness
Use the s or t keys until you see the desired brightness. Press the Enter key to accept the new
setting. There are four levels of brightness. The brightness can also be set using the BRIGT command
via the Serial Interface. Using the highest brightness setting may shorten the life of the display.
3.15 FACTORY DEFAULT SETTINGS
Press and hold the Max Reset key for ≈20 seconds. This causes the following functions to return to
their factory default settings. The defaults are listed as follows:
AC/DC........................... DC
Alarm ............................ Off
Auto Range................... Off
Baud ............................. 300
Brightness..................... 4
Fast Data Mode ............ Off
Filter.............................. Off
Gauss/Tesla.................. Gauss
Keypad.......................... Not Locked
Max Hold....................... Off
Range ........................... Highest Range For Probe
Relative......................... Off
Other gaussmeter calibration information and probe data are not affected by this reset. Zero the probe
after this operation.
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Operation
Lake Shore Model 421 Gaussmeter User’s Manual
3.16 PROBE CONSIDERATIONS
To avoid damage and for best results during use, the probes have a number of handling and accuracy
requirements that must be observed. Changing probes is discussed in Paragraph 3.16.1. Probe
handling is discussed in Paragraph 3.16.2. Probe operation is discussed in Paragraph 3.16.3. Finally,
accuracy considerations are provided in Paragraph 3.16.4.
3.16.1 Changing Probes
A 512-byte Electrically Erasable Programmable Read Only Memory (EEPROM) is included in each
probe. The EEPROM stores specific information that the gaussmeter requires for operation. The
information includes serial number, probe sensitivity, and field compensation data.
CAUTION: The probe must be connected to the rear of the instrument before applying power
to the gaussmeter. Probe memory may be erased if connected with power on.
When the instrument is powered up, the probe memory is downloaded to the gaussmeter. This is how
the gaussmeter knows which ranges are available and which error correction to apply. To change
probes, first turn power off, remove the existing probe, and then plug in the new probe. When power
is restored, the characteristics of the new probe are downloaded to the gaussmeter memory. Normal
operation may continue after the new probe offset is nulled using the Zero Probe operation.
If the instrument is powered up with no probe attached, the following message is displayed.
* * NO PROBE * *
Power off,attach
3.16.2 Probe Handling
Although every attempt has been made to make the probes as sturdy as possible, the probes are still
fragile. This is especially true for the exposed sensor tip of some transverse probes. Care should be
taken during measurements that no pressure is placed on the tip of the probe. The probe should only
be held in place by securing at the handle. The probe stem should never have force applied. Any
strain on the sensor may alter the probe calibration, and excessive force may destroy the Hall
generator.
CAUTION: Care must be exercised when handling the probe. The tip of the probe is very
fragile. Stressing the Hall sensor can alter its calibration. Any excess force can
easily break the sensor. Broken sensors are not repairable.
Avoid repeated flexing of the stem of a flexible probe. As a rule, the stem should not be bent more
than 45° from the base. See Figure 3-4. Force should never be applied to the tip of the probe. On all
probes, do not pinch or allow cables to be struck by any heavy or sharp objects. Although damaged
or severed cables should be returned to Lake Shore for repair, please understand that probes are not
always repairable.
When probes are installed on the gaussmeter but not in use, the protective tubes provided with many
probes should be placed over the probe handle and stem in order to protect the tip. When the
gaussmeter is not in use, the probes should be stored separately in some type of rigid container. The
cardboard and foam container that Lake Shore probes are shipped in may be retained for probe
storage. For further details on available accessories and probes, refer to Chapter 5.
Operation
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Lake Shore Model 421 Gaussmeter User’s Manual
Do not bend from
tip of probe
45°
45°
Stem
Flexible Transverse Probe
Maximum Bend Angle
The tip is
VERY FRAGILE
C-421-3-4.eps
Figure 3-4. Maximum Flexible Probe Bend Radius
3.16.3 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.
See Figure 3-5.
NOTE: For best results, the instrument and probe should warm up for at least 5 minutes before
zeroing the probe, and at least 30 minutes for rated accuracy. The probe and the zero
gauss chamber should be at the same temperature.
If the exact direction of the magnetic field is unknown, the proper magnitude is determined by turning
on Max Hold and slowly adjusting the probe. As the probe turns and the measured field rises and
falls, its maximum value is held on the display. Make note of the probe orientation at the maximum
reading to identify the field orientation.
Lake Shore Logo
Towards North Pole
N
B
S
Transverse Probe Orientation
For Positive (+) Measurement
B
S
N
Axial Probe Orientation
For Positive (+) Measurement
C-421-3-5.eps
Figure 3-5. Probe Orientation For Positive Measurement
3-14
Operation
Lake Shore Model 421 Gaussmeter User’s Manual
3.16.4 Probe Accuracy Considerations
NOTE: Probe readings are dependent upon the angle of the sensor in relation to the magnetic
field. The farther from 90° the angle between the probe and the field, the greater the
percentage of error. For example, a 5° deviation causes a 0.4% error, a 10° deviation
causes a 1.5% error, etc.
NOTE: For best results, the instrument and probe should warm up for at least 5 minutes before
zeroing the probe, and at least 30 minutes for rated accuracy. The probe and the zero
gauss chamber should be at the same temperature.
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. The zero probe function is used to null (cancel) out
the zero offset of the probe or small magnetic fields. It is normally used in conjunction with the zero
gauss chamber, but may also be used with an open probe (registering the local earth magnetic field).
Users wishing to cancel out large magnetic fields should use the Relative function. Refer to
Paragraph 3.8.
Probe temperature can also affect readings. Refer to the two separate temperature coefficients listed
on the specification sheet. The High Stability (HST) probes exhibit a low temperature coefficient of
gain due to the inherent thermal stability of the materials used in its construction.
Probe readings are dependent on the angle of the sensor (Hall sensor) in relation to the magnetic
field. Maximum output occurs when the flux vector is perpendicular to the plane of the sensor. This is
the condition that exists during factory calibration. The greater the deviation from orthogonality (from
right angles in either of three axes), the larger the error of the reading. For example, a 5° variance on
any one axis causes a 0.4% error, a 10° misalignment induces a 1.5% error, etc. See Figure 3-6.
Tolerance of instrument, probe, and magnet must be considered for making critical measurements.
The accuracy of the gaussmeter reading is better than ±0.20% of reading and ±0.05% of range.
Absolute accuracy readings for gaussmeters and Hall probes is a difficult specification to give,
because all the variables of the measurement are difficult to reproduce. For example, a 1° error in
alignment to the magnetic field causes a 0.015% reading error. Finally, the best probes have an
accuracy of ±0.15%. This implies that the absolute accuracy measurement of a magnetic field is not
going to reliably be better than ±0.15% under the best of circumstances, and more likely to be 0.20%
to 0.25%.
29.3%
45°
+B
13.4%
6.0%
3.4%
1.5%
0.4%
0%
Error
30°
20°
15°
10°
5°
0°
Deviation from
Perpendicular
(θ)
Effect of angular variations on
percentage of reading error
where % Error = (1 – cos θ) 100
C-421-3-6.eps
Figure 3-6. Effect Of Angle On Measurements
Operation
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This Page Intentionally Left Blank
3-16
Operation
Lake Shore Model 421 Gaussmeter User’s Manual
CHAPTER 4
REMOTE OPERATION
4.0
GENERAL
The Model 421 is equipped with an RS-232C serial computer interface. The interface allows computer
automation of instrument setup and field measurement data collection. Nearly every feature of the
instrument can be accessed through the computer interface. Interface capabilities including setup
information and Basic programs are provided in Paragraph 4.1. Interface commands including a
command summary are described in Paragraph 4.2.
4.1
SERIAL INTERFACE OVERVIEW
The serial interface used in the Model 421 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. The RS-232C standard is quite flexible and
allows many different configurations. However, any two devices claiming RS-232C compatibility cannot
necessarily be plugged together without interface setup. The remainder of this paragraph briefly
describes the key features of a serial interface that are supported by the instrument. A customer
supplied computer with similarly configured interface port is required to enable communication.
4.1.1
Physical Connection
The Model 421 has a 9 pin D-Subminiature plug on the rear panel for serial communication. The
original RS-232C standard specifies 25 pins but both 9- and 25-pin connectors are commonly used in
the computer industry. Many third party cables exist for connecting the instrument to computers with
either 9- or 25-pin connectors. Paragraph 6.5 gives the most common pin assignments for 9- and
25-pin connectors. Please note that not all pins or functions are supported by the Model 421.
The instrument serial connector is the plug half of a mating pair and must be matched with a socket
on the cable. If a cable has the correct wiring configuration but also has a plug end, a “gender
changer” can be used to mate two plug ends together.
The letters DTE near the interface connector stand for Data Terminal Equipment and indicate the pin
connection of the directional pins such as transmit data (TD) and receive data (RD). Equipment with
Data Communications Equipment (DCE) wiring can be connected to the instrument with a straight
through cable. As an example, pin 3 of the DTE connector holds the transmit line and pin 3 of the
DCE connector holds the receive line so the functions complement.
It is likely both pieces of equipment are wired in the DTE configuration. In this case pin 3 on one DTE
connector (used for transmit) must be wired to pin 2 on the other (used for receive). Cables that swap
the complementing lines are called null modem cables and must be used between two DTE wired
devices. Null modem adapters are also available for use with straight through cables. Paragraph
6.5.1 illustrates suggested cables that can be used between the instrument and common computers.
The instrument uses drivers to generate the transmission voltage levels required by the RS-232C
standard. These voltages are considered safe under normal operating conditions because of their
relatively low voltage and current limits. The drivers are designed to work with cables up to 50 feet in
length.
Remote Operation
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Lake Shore Model 421 Gaussmeter User’s Manual
4.1.2
Hardware Support
The Model 421 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. Half duplex
transmission allows the instrument to be either a transmitter or a receiver of data but not at the same
time. Communication speeds of 300, 1200 or 9600 baud are supported. The Baud rate is the only
interface parameter that can be changed by the user.
Hardware handshaking is not supported by the instrument. Handshaking is often used to guarantee
that data message strings do not collide and that no data is transmitted before the receiver is ready.
In this instrument appropriate software timing substitutes for hardware handshaking. User programs
must take full responsibility for flow control and timing as described in Paragraph 4.1.5.
4.1.3
Character Format
A character is the smallest piece of information that can be transmitted by the interface. Each
character is 10 bits long and contains data bits, bits for character timing and an error detection bit.
The instrument uses 7 bits for data in the ASCII format. One start bit and one stop bit are necessary
to synchronize consecutive characters. Parity is a method of error detection. One parity bit configured
for odd parity is included in each character.
ASCII letter and number characters are used most often as character data. Punctuation characters
are used as delimiters to separate different commands or pieces of data. Two special ASCII
characters, carriage return (CR 0DH) and line feed (LF 0AH), are used to indicate the end of a
message string.
Table 4-1. Serial Interface Specifications
Connector Type:
Connector Wiring:
Voltage Levels:
Transmission Distance:
Timing Format:
Transmission Mode:
Baud Rate:
Handshake:
Character Bits:
Parity:
Terminators:
Command Rate:
4.1.4
9-pin D-style plug
DTE
EIA RS-232C Specified
50 feet maximum
Asynchronous
Half Duplex
300, 1200, 9600
Software timing
1 Start, 7 Data, 1 Parity, 1 Stop
Odd
CR(0DH) LF(0AH)
20 commands per second maximum
Message Strings
A message string is a group of characters assembled to perform an interface function. There are
three types of message strings commands, queries and responses. The computer issues command
and query strings through user programs, the instrument issues responses. Two or more command
strings can be chained together in one communication but they must be separated by a semi-colon
(;). Only one query is permitted per communication but it can be chained to the end of a command.
The total communication string must not exceed 64 characters in length.
A command string is issued by the computer and instructs the instrument to perform a function or
change a parameter setting. The format is <command mnemonic><space><parameter
data><terminators>. Command mnemonics are listed in Paragraph 4.2. Parameter data necessary for
each one is described in Paragraph 4.2.1. Terminators must be sent with every message string.
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Lake Shore Model 421 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. Query mnemonics are listed in Paragraph 4.2. Parameter data if
necessary is described in Paragraph 4.2.1. Terminators must be sent with every message string. The
computer should expect a response very soon after a query is sent.
A response string is the instruments response or answer to a query string. The instrument will
respond only to the last query it receives. The response can be a reading value, status report or the
present value of a parameter. Response data formats are listed along with the associated queries in
Paragraph 4.2.1. The response is sent as soon as possible after the instrument receives the query.
Typically it takes 10 ms for the instrument to begin the response. Some responses take longer.
4.1.5
Message Flow Control
It is important to remember that the user program is in charge of the serial communication at all times.
The instrument can not initiate communication, determine which device should be transmitting at a
given time or guarantee timing between messages. All of this is the responsibility of the user program.
When issuing commands only the user program should:
•
Properly format and transmit the command including terminators as one string.
•
Guarantee that no other communication is started for 50 ms after the last character is transmitted.
•
Not initiate communication more than 20 times per second.
When issuing queries or queries and commands together the user program should:
•
Properly format and transmit the query including terminators as one string.
•
Prepare to receive a response immediately.
•
Receive the entire response from the instrument including the terminators.
•
•
Guarantee that no other communication is started during the response or for 50 ms after it
completes.
Not initiate communication more than 20 times per second.
Failure to follow these simple rules will result in inability to establish communication with the
instrument or intermittent failures in communication.
4.1.6
Changing Baud Rate
To use the Serial Interface, you must first set the Baud rate. Press Interface key to display the
following screen.
Select With °®
Baud ¡3 12 96
Press the s or t keys to cycle through the choices of 300, 1200, or 9600 Baud. The rate selected
will have a right pointing arrow (Æ) immediately to the left. Press Enter to accept the new number.
Remote Operation
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Lake Shore Model 421 Gaussmeter User’s Manual
4.1.7
Serial Interface Basic 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 4.1.7.1 for instructions on how to
setup the program. The Visual Basic code is provided in Table 4-3. The second program was written
in Quick Basic. Refer to Paragraph 4.1.7.2 for instructions on how to setup the program. The Quick
Basic code is provided in Table 4-4. Finally, a description of operation common to both programs is
provided in Paragraph 4.1.7.3. While the hardware and software required to produce and implement
these programs not included with the instrument, the concepts illustrated apply to almost any
application where these tools are available.
4.1.7.1
Visual Basic Serial Interface Program Setup
The serial interface program (Table 4-3) works with Visual Basic 6.0 (VB6) on an IBM PC
(or compatible) with a Pentium-class processor. A Pentium 90 or higher is recommended, running
Windows 95 or better, with a serial interface. It uses the COM1 communications port at 9600 Baud.
Use the following procedure to develop the Serial Interface Program in Visual Basic.
1.
2.
3.
4.
5.
6.
7.
8.
9.
Start VB6.
Choose Standard EXE and select Open.
Resize form window to desired size.
On the Project Menu, click Components to bring up a list of additional controls available in VB6.
Scroll through the controls and select Microsoft Comm Control 6.0. Select OK. In the toolbar at
the left of the screen, the Comm Control will have appeared as a telephone icon.
Select the Comm control and add it to the form.
Add controls to form:
a. Add three Label controls to the form.
b. Add two TextBox controls to the form.
c. Add one CommandButton control to the form.
d. Add one Timer control to the form.
On the View Menu, select Properties Window.
In the Properties window, use the dropdown list to select between the different controls of the
current project.
10. Set the properties of the controls as defined in Table 4-2.
11. Save the program.
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Lake Shore Model 421 Gaussmeter User’s Manual
Table 4-2. Serial Interface Program Control Properties
Current Name
Label1
Label2
Label3
Text1
Text2
Command1
Form1
Timer1
Property
Name
Caption
Name
Caption
Name
Caption
Name
Text
Name
Text
Name
Caption
Default
Name
Caption
Enabled
Interval
New Value
lblExitProgram
Type “exit” to end program.
lblCommand
Command
lblResponse
Response
txtCommand
<blank>
txtResponse
<blank>
cmdSend
Send
True
frmSerial
Serial Interface Program
False
10
12. Add code (provided in Table 4-3).
a. In the Code Editor window, under the Object dropdown list, select (General). Add the
statement: Public gSend as Boolean
b. Double Click on cmdSend. Add code segment under Private Sub cmdSend_Click( )
as shown in Table 4-3.
c. In the Code Editor window, under the Object dropdown list, select Form. Make sure the
Procedure dropdown list is set at Load. The Code window should have written the segment
of code: Private Sub Form_Load( ). Add the code to this subroutine as shown in Table 4-3.
d. Double Click on the Timer control. Add code segment under Private Sub Timer1_Timer()
as shown in Table 4-3.
e. Make adjustments to code if different Com port settings are being used.
13. Save the program.
14. Run the program. The program should resemble the following.
15. Type in a command or query in the Command box as described in Paragraph 4.1.7.3.
16. Press Enter or select the Send button with the mouse to send command.
17. Type Exit and press Enter to quit.
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Lake Shore Model 421 Gaussmeter User’s Manual
Table 4-3. Visual Basic Serial Interface Program
Public gSend As Boolean
Private Sub cmdSend_Click()
gSend = True
End Sub
Private Sub Form_Load()
Dim strReturn As String
Dim strHold As String
Dim Term As String
Dim ZeroCount As Integer
Dim strCommand As String
'Global used for Send button state
'Routine to handle Send button press
'Set Flag to True
'Main code section
'Used to return response
'Temporary character space
'Terminators
'Counter used for Timing out
'Data string sent to instrument
frmSerial.Show
Term = Chr(13) & Chr(10)
ZeroCount = 0
strReturn = ""
strHold = ""
If frmSerial.MSComm1.PortOpen = True Then
frmSerial.MSComm1.PortOpen = False
End If
frmSerial.MSComm1.CommPort = 1
frmSerial.MSComm1.Settings = "9600,o,7,1"
frmSerial.MSComm1.InputLen = 1
frmSerial.MSComm1.PortOpen = True
'Show main window
'Terminators are <CR><LF>
'Initialize counter
'Clear return string
'Clear holding string
'Close serial port to change settings
Do
DoEvents
Loop Until gSend = True
gSend = False
'Wait loop
'Give up processor to other events
'Loop until Send button pressed
'Set Flag as false
strCommand = frmSerial.txtCommand.Text
strReturn = ""
'Get Command
'Clear response display
strCommand = UCase(strCommand)
If strCommand = "EXIT" Then
End
End If
'Set all characters to upper case
'Get out on EXIT
'Example of Comm 1
'Example of 9600 Baud,Parity,Data,Stop
'Read one character at a time
'Open port
Do
frmSerial.MSComm1.Output = strCommand & Term
'Send command to instrument
If InStr(strCommand, "?") <> 0 Then
'Check to see if query
While (ZeroCount < 20) And (strHold <> Chr$(10)) 'Wait for response
If frmSerial.MSComm1.InBufferCount = 0 Then
'Add 1 to timeout if no character
frmSerial.Timer1.Enabled = True
Do
DoEvents
'Wait for 10 millisecond timer
Loop Until frmSerial.Timer1.Enabled = False
ZeroCount = ZeroCount + 1
'Timeout at 2 seconds
Else
ZeroCount = 0
'Reset timeout for each character
strHold = frmSerial.MSComm1.Input
'Read in one character
strReturn = strReturn + strHold
'Add next character to string
End If
Wend
'Get characters until terminators
If strReturn <> "" Then
'Check if string empty
strReturn = Mid(strReturn, 1, InStr(strReturn, Term) - 1) 'Strip terminators
Else
strReturn = "No Response"
'Send No Response
End If
frmSerial.txtResponse.Text = strReturn
'Put response in textbox on main form
strHold = ""
'Reset holding string
ZeroCount = 0
'Reset timeout counter
End If
Loop
End Sub
Private Sub Timer1_Timer()
'Routine to handle Timer interrupt
frmSerial.Timer1.Enabled = False
'Turn off timer
End Sub
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Remote Operation
Lake Shore Model 421 Gaussmeter User’s Manual
4.1.7.2
Quick Basic Serial Interface Program Setup
The serial interface program (Table 4-4) works with QuickBasic 4.0/4.5 or Qbasic on an IBM PC
(or compatible) running DOS or in a DOS window with a serial interface. It uses the COM1
communication port at 9600 Baud. Use the following procedure to develop the Serial Interface
Program in Quick Basic.
1.
2.
3.
4.
5.
6.
7.
8.
Start the Basic program.
Enter the program exactly as presented in Table 4-4.
Adjust the Com port and Baud rate in the program as necessary.
Lengthen the "TIMEOUT" count if necessary.
Save the program.
Run the program.
Type a command query as described in Paragraph 4.1.7.3.
Type "EXIT" to quit the program.
Table 4-4. Quick Basic Serial Interface Program
CLS
'Clear screen
PRINT " SERIAL COMMUNICATION PROGRAM"
PRINT
TIMEOUT = 2000
'Read timeout (may need more)
BAUD$ = "9600"
TERM$ = CHR$(13) + CHR$(10)
'Terminators are <CR><LF>
OPEN "COM1:" + BAUD$ + ",O,7,1,RS" FOR RANDOM AS #1 LEN = 256
LOOP1: LINE INPUT "ENTER COMMAND (or EXIT):"; CMD$
CMD$ = UCASE$(CMD$)
IF CMD$ = "EXIT" THEN CLOSE #1: END
CMD$ = CMD$ + TERM$
PRINT #1, CMD$;
IF INSTR(CMD$, "?") <> 0 THEN
RS$ = ""
N = 0
'Get command from keyboard
'Change input to upper case
'Get out on Exit
'Send command to instrument
'Test for query
'If query, read response
'Clr return string and count
WHILE (N < TIMEOUT) AND (INSTR(RS$, TERM$) = 0)
IN$ = INPUT$(LOC(1), #1)
'Get
IF IN$ = "" THEN N = N + 1 ELSE N = 0
'Add
RS$ = RS$ + IN$
'Add
WEND
'Get
'Wait for response
one character at a time
1 to timeout if no chr
next chr to string
chrs until terminators
IF RS$ <> "" THEN
'See if return string is empty
RS$ = MID$(RS$, 1, (INSTR(RS$, TERM$) - 1)) 'Strip off terminators
PRINT "RESPONSE:"; RS$
'Print response to query
ELSE
PRINT "NO RESPONSE"
'No response to query
END IF
END IF
'Get next command
GOTO LOOP1
Remote Operation
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Lake Shore Model 421 Gaussmeter User’s Manual
4.1.7.3
Program Operation
Once either 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.
Identification query. Instrument will return a string
identifying itself.
RESPONSE: LSCI,MODEL421,0,070199[term]
ENTER COMMAND? *IDN?
ENTER COMMAND? FIELD?
Field reading query. Instrument will return a string with
the present field reading.
RESPONSE: +12.345[term]
ENTER COMMAND? FIELDM?
Field multiplier query. Instrument will return a string with
the field units multiplier. Blank indicated gauss,
k indicates kilo gauss, etc.
RESPONSE: k[term]
ENTER COMMAND? RANGE 0
Range command. Instrument will change the field range
to the highest setting. No response will be sent.
ENTER COMMAND? RANGE?
Range query. Instrument will return a string with the
present range setting.
RESPONSE: 0[term]
ENTER COMMAND? RANGE 0;RANGE?
Range command followed by range query. Instrument
will change range to highest setting then return a string
with the present range setting.
RESPONSE: 0[term]
The following are additional notes on using either Serial Interface program.
•
•
4-8
If you enter a correctly spelled query without a “?,” nothing will be returned. Incorrectly spelled
commands and queries are ignored. Commands and queries and should have a space
separating the command and associated parameters.
Leading zeros and zeros following a decimal point are not needed in a command string, but
they will be sent in response to a query. A leading “+” is not required but a leading “–” is
required.
Remote Operation
Lake Shore Model 421 Gaussmeter User’s Manual
4.1.8
Trouble Shooting
New Installation
1. Check instrument baud rate
2. Make sure transmit (TD) signal line from the instrument is routed to receive (RD) on the computer
and vice versa. (Use a null modem adapter if not).
3. Always send terminators
4. Send entire message string at one time including terminators. (Many terminal emulation programs
do not.)
5. Send only one simple command at a time until communication is established.
6. Be sure to spell commands correctly and use proper syntax.
Old Installation No Longer Working
1. Power instrument off then on again to see if it is a soft failure.
2. Power computer off then on again to see if communication port is locked up.
3. Verify that baud rate has not been changed on the instrument during a memory reset.
4. Check all cable connections.
Intermittent Lockups
1. Check cable connections and length.
2. Increase delay between all commands to 100 ms to make sure instrument is not being over
loaded.
4.2
SERIAL INTERFACE COMMAND SUMMARY
This paragraph provides a summary of the Serial Interface Commands. The summary is divided into
two command groups: Interface Commands and Device Specific Commands. Interface Commands are
detailed in Paragraph 4.2.1. Device specific commands are detailed in Paragraph 4.2.2. A list of all
commands is provided in Table 4-5.
Brief Description of Function
Command Name
Syntax of what user must input
Information returned in
response to the query
Response format – see Key below
Remarks as appropriate
Key:
Q
?
aa…
nn…
[term]
<…>
<state>
<field value>
<multiplier>
Remote Operation
ALMH?
Input:
High Alarm Setpoint Query
ALMH?[term]
Returned:
<field value>[term]
Format:
nnn.nn (Refer to command for description)
Remarks:
Use ALMHM? to determine units multiplier.
Begins common interface command.
Required to identify queries.
String of alpha numeric characters.
String of number characters.
Terminator characters.
Indicated a parameter field, many are command specific.
Parameter field with only On/Off or Enable/Disable states.
Field values have the range and resolution of displayed field readings. Field queries must
be used with associated multiplier and units queries to obtain a complete field reading.
Spaces will be returned in place of unused digits.
µ = micro = 10-6, m = milli = 10-3, (blank) = unity, k = kilo = 103.
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Lake Shore Model 421 Gaussmeter User’s Manual
Table 4-5. Serial Interface Commands
Command
Function
Page
Interface Commands
QIDN?
Query Identification *..............................4-11
QRST
Reset Instrument ....................................4-11
BAUD
Set Serial Interface Baud Rate...............4-11
BAUD?
Serial Interface Baud Rate Query ..........4-11
Device Specific Commands
ACDC
AC/DC Field Measurement Command ...4-12
ACDC?
AC/DC Field Measurement Query..........4-12
ALARM
Alarm On/Off Command.........................4-12
ALARM?
Alarm On/Off Query................................4-12
ALMB
Audible Alarm Command .......................4-12
ALMB?
Audible Alarm Query ..............................4-12
ALMH
High Alarm Setpoint Command..............4-12
ALMH?
High Alarm Setpoint Query.....................4-13
ALMHM?
High Alarm Setpoint Multiplier Query .....4-13
ALMIO
Alarm Inside/Outside Command ............4-13
ALMIO?
Alarm Inside/Outside Query ...................4-13
ALML
Low Alarm Setpoint Command...............4-13
ALML?
Low Alarm Setpoint Query .....................4-13
ALMLM?
Low Alarm Setpoint Multiplier Query ......4-14
ALMS?
Alarm Status Query ................................4-14
ALMSORT Sort Pass/Fail Command .......................4-14
ALMSORT? Sort Pass/Fail Query ..............................4-14
AUTO
Auto Range Command...........................4-14
AUTO?
Auto Range Query .................................4-14
BRIGT
Display Brightness Command ................4-14
BRIGT?
Display Brightness Query.......................4-15
Command
FAST
FAST?
FIELD?
FIELDM?
FILT
FILT?
LOCK
LOCK?
MAX
MAX?
MAXC
MAXR?
MAXRM?
RANGE
RANGE?
REL
REL?
RELR?
RELRM?
RELS
RELS?
RELSM?
SNUM?
TYPE?
UNIT
UNIT?
ZCAL
Function
Page
Fast Data Mode Command ....................4-15
Fast Data Mode Query ...........................4-15
Field Reading Query ..............................4-15
Field Multiplier Query .............................4-15
Display Filter Command.........................4-15
Display Filter Query................................4-15
Keypad Lock Command.........................4-16
Keypad Lock Query................................4-16
Max Hold Command ..............................4-16
Max Hold Query .....................................4-16
Max Reset Command ............................4-16
Max Reading Query ...............................4-16
Max Reading Multiplier Query................4-16
Manual Range Command ......................4-17
Manual Range Query .............................4-17
Relative Mode Command.......................4-17
Relative Mode Query .............................4-17
Relative Mode Reading Query ...............4-17
Relative Mode Reading Multiplier ..........4-17
Relative Mode Setpoint Command ........4-18
Relative Mode Setpoint Query ...............4-18
Relative Mode Setpoint Multiplier...........4-18
Probe Serial Number Query * ................4-18
Probe Type Query * ...............................4-18
Gauss or Tesla Unit Command..............4-19
Gauss or Tesla Unit Query.....................4-19
Zero Probe Command............................4-19
* These commands are only available over the computer interface, i.e., there are no front panel equivalent
commands: QIDN, SNUM, and TYPE.
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Lake Shore Model 421 Gaussmeter User’s Manual
4.2.1
Interface Commands
QIDN?
Input:
Identification Query
QIDN?[term]
Returned: <manufacturer>,<model>,0,<date>[term]
Format:
aaaa,aaaaaaaa,n,mmddyy
<manufacture> Manufacturer ID
<model>
Instrument model number
0
Indicates no serial number included
<date>
Instrument firmware revision date
Example: LSCI,MODEL421,0,070199
QRST
Input:
Reset Command
QRST[term]
Remarks: This command resets the instrument to its power up state. Similar to turning the power off
and back on again.
BAUD
Set Serial Interface Baud Rate
Input:
BAUD <baud>[term]
Format:
n
<baud>
BAUD?
Input:
0 = 300, 1 = 1200, and 2 = 9600 baud
Serial Interface Baud Rate Query
BAUD?[term]
Returned: <baud>[term]
Format:
n
(Refer to command for description)
Remote Operation
4-11
Lake Shore Model 421 Gaussmeter User’s Manual
4.2.2
Device Specific Commands
ACDC
AC or DC Field Measurement Command
Input:
ACDC <mode>[term]
Format:
n
<mode>
ACDC?
Input:
0 = DC, 1 = AC. Refer to Paragraph 3.3.
AC or DC Field Measurement Query
ACDC?[term]
Returned: <mode>[term]
Format:
n
(Refer to command for description)
ALARM
Alarm On/Off Command
Input:
ALARM <state>[term]
Format:
n
<state>
ALARM?
Input:
0 = Off, 1 = On. Refer to Paragraph 3.9.
Alarm On/Off Query
ALARM?[term]
Returned: <state>[term]
Format:
n
(Refer to command for description)
ALMB
Audible Alarm Beeper Enable/Disable Command
Input:
ALMB <state>[term]
Format:
n
<state>
ALMB?
Input:
0 = Disabled, 1 = Enabled
Audible Alarm Beeper Enable/Disable Query
ALMB?[term]
Returned: <state>[term]
Format:
n
(Refer to command for description)
ALMH
Input:
High Alarm Setpoint Command
ALMH <field value>[term]
Format:
±nnn.nn
<field value>
Enter sign, 4 or 5 digits, and place decimal point appropriate to range.
Remarks: New value is entered on the same field range as the old value. Setting value to zero first will
change the setting range to present display range.
4-12
Remote Operation
Lake Shore Model 421 Gaussmeter User’s Manual
Device Specific Commands (Continued)
ALMH?
Input:
High Alarm Setpoint Query
ALMH?[term]
Returned: <field value>[term]
Format:
±nnn.nn
(Refer to command for description)
Remarks: Use ALMHM? to determine units multiplier.
ALMHM?
Input:
High Alarm Setpoint Multiplier Query
ALMHM?[term]
Returned: <multiplier>[term]
Format:
a
<multiplier>
µ = micro = 10-6, m = milli = 10-3, (blank) = unity, k = kilo = 103
Remarks: Used with ALMH? query.
ALMIO
Input:
Alarm Inside/Outside Command
ALMIO <inout>[term]
Format:
n
<inout>
0 = Outside or 1 = Inside
Remarks: Instructs alarm feature to cause an active alarm state when the field reading is either inside of
or outside of the high and low setpoint values. Refer to Paragraph 3.9.
ALMIO?
Input:
Alarm Inside/Outside Query
ALMIO?[term]
Returned: <inout>[term]
Format:
n
(Refer to command for description)
ALML
Input:
Low Alarm Setpoint Command
ALML <field value>[term]
Format:
±nnn.nn
<field value>
Enter sign, 4 or 5 digits, and place decimal point appropriate to range.
Remarks: New value is entered on the same field range as the old value. Setting value to zero first will
change the setting range to present display range.
ALML?
Input:
Low Alarm Setpoint Query
ALML?[term]
Returned: <field value>[term]
Format:
±nnn.nn (Refer to command for description)
Remarks: Use ALMLM? to determine units multiplier.
Remote Operation
4-13
Lake Shore Model 421 Gaussmeter User’s Manual
Device Specific Commands (Continued)
ALMLM?
Input:
Low Alarm Setpoint Multiplier Query
ALMLM?[term]
Returned: <multiplier>[term]
Format:
a
<multiplier>
µ = micro = 10-6, m = milli = 10-3, (blank) = unity, k = kilo = 103
Remarks: Used with ALML? query.
ALMS?
Input:
Alarm Status Query
ALMS?[term]
Returned: <state>[term]
Format:
n
<state>
0 = alarm in normal state, 1 = alarm active
Remarks: Either a high or a low alarm can cause an active alarm status.
ALMSORT
Sort Pass/Fail Command
Input:
ALMSORT <state>[term]
Format:
n
<state>
ALMSORT?
Input:
0 = Off, 1 = On
Sort Pass/Fail Query
ALMSORT?[term]
Returned: <state>[term]
Format:
n
(Refer to command for description)
AUTO
Auto Range Command
Input:
AUTO <state>[term]
Format:
n
<state>
AUTO?
Input:
0 = Auto Range Off, 1 = Auto Range On. Refer to Paragraph 3.5.
Auto Range Query
AUTO?[term]
Returned: <state>[term]
Format:
n
(Refer to command for description)
BRIGT
4-14
Front Panel Display Brightness Command
Input:
BRIGT <brightness>[term]
Format:
n
<brightness>
0 or 1 = first setting (dimmest), 2 or 3 = second setting, 4 or 5 = third setting,
6 or 7 fourth setting (brightest). Default setting is 4. Refer to Paragraph 3.14.
Remote Operation
Lake Shore Model 421 Gaussmeter User’s Manual
Device Specific Commands (Continued)
BRIGT?
Input:
Front Panel Display Brightness Query
BRIGT?[term]
Returned: <brightness>[term]
Format:
n
(Refer to command for description)
FAST
Input:
Fast Data Mode Command
FAST <state>[term]
Format:
n
<state>
0 = Off, 1 = On
Remarks: Fast Data Mode reaches data rates up to 18 readings per second via the Serial Interface with
a corresponding increase in corrected analog output. The front panel display does not
function in this mode. Refer to Paragraph 3.12.
FAST?
Input:
Fast Data Mode Query
FAST?[term]
Returned: <state>[term]
Format:
n
(Refer to command for description)
FIELD?
Input:
Magnetic Field Reading Query
FIELD?[term]
Returned: <field value>[term]
Format:
±nnn.nn
<field value>
Returns sign, 4 or 5 digits, and places decimal point appropriate to range.
Remarks: Use FIELDM? to determine units multiplier and UNITS? to determine gauss or tesla units.
FIELDM?
Input:
Field Reading Multiplier Query
FIELDM?[term]
Returned: <multiplier>[term]
Format:
a
<multiplier>
µ = micro = 10-6, m = milli = 10-3, (blank) = unity, k = kilo = 103
Remarks: Used with FIELD? query.
FILT
Input:
Display Filter Command
FILT <state>[term]
Format:
n
<state>
0 = Off, 1 = On
Remarks: Quiets the display reading. Refer to Paragraph 3.4.
FILT?
Input:
Display Filter Query
FILT?[term]
Returned: <state>[term]
Format:
n
(Refer to command for description)
Remote Operation
4-15
Lake Shore Model 421 Gaussmeter User’s Manual
Device Specific Commands (Continued)
LOCK
Input:
Front Panel Keypad Lock Command
LOCK <state>[term]
Format:
n
<state>
0 = Unlocked, 1 = Locked
Remarks: Locks out all front panel entries except pressing the Alarm key to silence alarms. Refer to
Paragraph 3.13.
LOCK?
Input:
Front Panel Keypad Lock Query
LOCK?[term]
Returned: <state>[term]
Format:
n
(Refer to command for description)
MAX
Input:
Max Hold Command
MAX <state>[term]
Format:
n
<state>
0 = Off, 1 = On
Remarks: Works with the MAXR and MAXC commands. Refer to Paragraph 3.7.
MAX?
Input:
Max Hold Query
MAX?[term]
Returned: <state>[term]
Format:
n
(Refer to command for description)
MAXC
Input:
Max Reset Command
MAXC[term]
Remarks: This command initiates a Max Reset. Upon entry, the Max Hold function is zeroed out and a
new peak is captured. Refer to Paragraph 3.7.
MAXR?
Input:
Max Reading Query
MAXR?[term]
Returned: <field value>[term]
Format:
+nnn.nn
<field value>
Returns plus (+) sign, 4 or 5 digits, and places decimal point appropriate
to range.
Remarks: Use MAXRM? to determine units multiplier and UNITS? to determine gauss or tesla units.
MAXRM?
Input:
Max Reading Multiplier Query
MAXRM?[term]
Returned: <multiplier>[term]
Format:
a
<multiplier>
µ = micro = 10-6, m = milli = 10-3, (blank) = unity, k = kilo = 103
Remarks: Used with MAXR? query.
4-16
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Lake Shore Model 421 Gaussmeter User’s Manual
Device Specific Commands (Continued)
RANGE
Manual Range Command
Input:
RANGE <range>[term]
Format:
n
<range>
0 = first range (highest) , 1 = second range, 2 = third range,
3 = fourth range (lowest)
Remarks: Range depends on type of probe installed. There are four ranges possible for each probe.
Refer to Paragraph 3.5.
RANGE?
Input:
Manual Range Query
RANGE?[term]
Returned: <range>[term]
Format:
n
(Refer to command for description)
REL
Input:
Relative Mode Command
REL <state>[term]
Format:
n
<state>
0 = Off, 1 = On
Remarks: Works with the RELR(?), RELRM(?), RELS(?), and RELSM(?) commands. Remote operation
is slightly different from front panel operation described in Paragraph 3.8. From the front
panel, the current reading is captured as the setpoint when Relative is turned on. However,
when activated by remote command, the initial relative setpoint is zero. The RELS command
is used to enter a setpoint.
REL?
Input:
Relative Mode Query
REL?[term]
Returned: <state>[term]
Format:
n
(Refer to command for description)
RELR?
Input:
Relative Mode Reading Query
RELR?[term]
Returned: <field value>[term]
Format:
±nnn.nn
<field value>
Returns sign, 4 or 5 digits, and places decimal point appropriate to range.
Remarks: Use RELRM? to determine units multiplier and UNITS? to determine gauss or tesla units.
RELRM?
Input:
Relative Mode Reading Multiplier Query
RELRM?
Returned: <multiplier>[term]
Format:
a
<multiplier>
µ = micro = 10-6, m = milli = 10-3, (blank) = unity, k = kilo = 103
Remarks: Used with RELR? query.
Remote Operation
4-17
Lake Shore Model 421 Gaussmeter User’s Manual
Device Specific Commands (Continued)
RELS
Input:
Relative Mode Setpoint Command
RELS <setpoint>[term]
Format:
nnn.nn
<setpoint>
Relative mode setpoint value with up to 5 digits resolution.
Remarks: New value is entered on the same field range as the old value. Setting value to zero first will
change the setting range to present display range.
RELS?
Input:
Relative Mode Setpoint Query
RELS?[term]
Returned: <setpoint>[term]
Format:
nnn.nn (Refer to command for description)
Remarks: Use RELSM? to determine units multiplier.
RELSM?
Input:
Relative Mode Setpoint Multiplier Query
RELSM?[term]
Returned: <multiplier>[term]
Format:
a
<multiplier>
µ = micro = 10-6, m = milli = 10-3, (blank) = unity, k = kilo = 103
Remarks: Used with RELS? query.
SNUM?
Input:
Probe Serial Number Query
SNUM?[term]
Returned: <serial>[term]
Format:
annnnnnnnn
<serial>
TYPE?
Input:
The current probe serial number format is Hnnnnn, though there is room for
up to a ten-character response.
Probe Type Query
TYPE?[term]
Returned: <probe>[term]
Format:
n
<probe>
0 = High Sensitivity (HSE), 1 = High Stability (HST),
2 = Ultra-High Sensitivity (UHS)
4-18
Remote Operation
Lake Shore Model 421 Gaussmeter User’s Manual
Device Specific Commands (Continued)
UNIT
Gauss or Tesla Unit Command
Input:
UNIT <unit>[term]
Format:
a
<unit>
UNIT?
Input:
G = gauss, T = tesla. Refer to Paragraph 3.2.
Gauss or Tesla Unit Query
UNIT?[term]
Returned: <unit>[term]
Format:
a
(Refer to command for description)
ZCAL
Input:
Zero Probe Command
ZCAL[term]
Remarks: This command initiates the Zero Probe function. Place probe in the Zero Gauss Chamber first
and then enter the ZCAL command. Refer to Paragraph 3.6.
Remote Operation
4-19
Lake Shore Model 421 Gaussmeter User’s Manual
This Page Intentionally Left Blank
4-20
Remote Operation
Lake Shore Model 421 Gaussmeter User’s Manual
CHAPTER 5
ACCESSORIES AND PROBES
5.0
GENERAL
This chapter provides lists of Model 421 Gaussmeter accessories and probes. Accessories are
described in Paragraph 5.1. Probes are described in Paragraph 5.2. Helmholtz coils are described
in Paragraph 5.3. Finally, reference magnets are described in Paragraph 5.4.
5.1
ACCESSORIES
Accessories are devices that perform a secondary duty as an aid or refinement to the primary unit.
A list of accessories available for the Model 421 are as follows:
Model
106-741
4030-XX
Description of Accessory
Terminal Block Mating Connector. One 3-pin connector for Alarm Relay. See Figure 6-4.
Hall Probe Stand. This moveable probe stand consists of a 30 mm square post mounted
on a 180 × 130 × 22.5 mm thick base plate. A probe holder is integrated into the stand.
The holder can be moved up or down and fixed at any angle and location along the post.
Two models are available as follows. Consult factory for other post heights.
4030-12 Hall probe stand with 12 inch tall post and probe holder to accept
3/8 inch diameter Hall probe handle.
4030-24 Hall probe stand with 24 inch tall post and probe holder to accept
3/8 inch diameter Hall probe handle.
4060
Standard Zero Gauss Chamber. Used for standard probe field nulling.
Size: 32 × 32 × 61 mm (1.3 × 1.3 × 2.4 inches).
Bore: 12 mm diameter × 51 mm deep (0.5 × 2 inches). See Figure 5-12.
4065
Large Zero Gauss Chamber. Used for Gamma Probe™ field nulling.
Size: 57 × 53 × 305 mm (2.3 × 2.1 × 12 inches).
Bore: 19 mm diameter × 279 mm deep (0.8 × 11 inches). See Figure 5-13.
MAN-421
Model 421 Gaussmeter User’s Manual.
MCBL-XX
Hall Generator Cable Assembly. The MCBL Cable Assembly connects a discrete Hall
generator to the Model 421 Gaussmeter. The cable ships with the HALLCAL.EXE program
which permits cable PROM programming through a PC (or compatible) computer serial port.
Because of the many calibration intricacies, the user is responsible for measurement
accuracy. Refer to Appendix C.
MCBL-6
Hall Generator Cable Assembly – 2 meters (6 feet) long
MCBL-20
Hall Generator Cable Assembly – 6 meters (20 feet) long
Accessories and Probes
5-1
Lake Shore Model 421 Gaussmeter User’s Manual
Accessories (Continued)
MODEL
NUMBER
DESCRIPTION OF ACCESSORY
Helmholtz Coils. Provides stable low magnetic field when used with customer-supplied
power supply. Often used to provide reference field to help check gaussmeter accuracy.
Three coils are available as follows. Refer to Paragraph 5.3.
MH-2.5
Helmholtz Coil, 2.5-inch inner diameter, field strength: ≈30 G @ 1 A,
maximum continuous current: 2 A, coil resistance: ≈3 Ω. See Figure 5-8.
MH-6
Helmholtz Coil, 6-inch inner diameter, field strength: ≈50 G @ 2 A,
maximum continuous current: 2 A, Coil Resistance: ≈10 Ω. See Figure 5-9.
MH-12
Helmholtz Coil. 12-inch inner diameter, field strength: ≈25 G @ 1 A,
maximum continuous current: 2 A, Coil Resistance: ≈20 Ω. See Figure 5-10.
MH-XX
MRA-XXX
MRT-XXX
Reference Magnets. High-quality reference magnets are available in transverse (flat) and
axial (round) configurations. Refer to Paragraph 5.4 and see Figure 5-11.
MRA-312-100 Axial Reference Magnet: 0.312" inside diameter, 100 G, 1%
MRA-312-200 Axial Reference Magnet: 0.312" inside diameter, 200 G, 1%
MRA-312-300 Axial Reference Magnet: 0.312" inside diameter, 300 G, 1%
MRA-312-500 Axial Reference Magnet: 0.312" inside diameter, 500 G, 1%
MRA-312-1K Axial Reference Magnet: 0.312" inside diameter, 1 kG, 1%
MRA-312-2K Axial Reference Magnet: 0.312" inside diameter, 2 kG, 1%
MRT-062-200 Transverse Reference Magnet: 0.062" gap, 200 G, 1%
MRT-062-500 Transverse Reference Magnet: 0.062" gap, 500 G, 1%
MRT-062-1K Transverse Reference Magnet: 0.062" gap, 1 kG, 0.5%
MRT-062-2K Transverse Reference Magnet: 0.062" gap, 2 kG, 0.5%
MRT-062-5K Transverse Reference Magnet: 0.062" gap, 5 kG, 0.5%
MRT-062-10K Transverse Reference Magnet: 0.062" gap, 10 kG, 5%
MRT-343-50
Transverse Reference Magnet: 0.343" gap, 50 G, 1%
MRT-343-100 Transverse Reference Magnet: 0.343" gap, 100 G, 1%
Probe Extension Cables. Four cables are available. Each extension cable contains a
EEPROM for calibration data. Each extension cable must be matched to a specific probe.
To maintain probe accuracy, that probe and extension cable must be calibrated together
at Lake Shore. The probe will exhibit its full accuracy if used without the extension cable.
Part numbers and cables lengths are defined as follows:
MPEC-XXX
MPEC-10
Probe Extension Cable – 3 meters (10 feet)
MPEC-25
Probe Extension Cable – 7.6 meters (25 feet)
MPEC-50
Probe Extension Cable – 15.2 meters (50 feet)
MPEC-100 Probe Extension Cable – 30.5 meters (100 feet)
RM-1/2
RM-2
5-2
Half-Rack Mounting Kit for One Gaussmeter. Half-length mounting panel and mounting
ears to attach a Model 421 to a 483 mm (19-inch) rack mount space. See Figure 5-14.
Rack Mounting Shelf for Two Gaussmeters. Mounting shelf to attach two Model 421
Gaussmeters to a 483 mm (19-inch) rack mount space. See Figure 5-15.
Accessories and Probes
Lake Shore Model 421 Gaussmeter User’s Manual
5.2
LAKE SHORE STANDARD PROBES
In addition to the probe included with the purchase, additional probes are available for use with the
Model 421 Gaussmeter. Examples include Axial, Flexible Axial, Transverse, Flexible Transverse,
Robust Transverse, Tangential, and the Gamma Probe. Because the Model 421 covers such a wide
magnetic field range (0.01 mG to 300 kG), three probe ranges are available: High Stability (HST), High
Sensitivity (HSE), and Ultra-High Sensitivity (UHS). Please consult the factory for availability of probe
types not detailed in these figures. Information on Hall generators is presented in Appendix C.
5.2.1
Probe Selection Criteria
Some guidelines are provided below to aid in the selection of a probe for you application.
1. Choose a probe to match the application. Do not buy more accuracy, field range, or fragility than
is actually necessary.
2. The thinner a probe, the more fragile it is. Try to avoid the temptation to select an easily damaged
probe based on a possible, but not probable, future application. For instance, avoid using an
exposed-device probe such as a Model MFT-3E03 or MNA-1904 type for general field
measurements. Once a stem or sensor has been damaged, the probe is not repairable.
3. Metal enclosed probes, such as the Model MMT-6J08 and MMA-2508 types, offer the greatest
amount of protection to the Hall sensor, and therefore are the most rugged types.
4. Be cautious about using aluminum stemmed, transverse probes, such as the Model MMT-6J08
type, where AC magnetic fields are to be measured. Eddy currents in the stem material can affect
reading accuracy. A superior choice for AC measurements would b the Model MNT-4E04 type
fiberglass-epoxy stem probes.
5. Several stem lengths are offered for each probe type. User preferences or test set-up dimensions
usually determine the final selection. Longer stems are more susceptible to accidental bending
(in many cases not catastrophic, but bothersome). Stem length does not affect performance.
6. Be aware of the differences in the probe “active areas” shown on the data sheet. A Hall effect
probe will indicate the average field value sensed over that total active area. Thus, when
measuring magnetic fields with a high gradient across the sensor width, choose the smallest
active area practical (keeping in mind, however, the fragility rule in number 2 above).
7. Lake Shore gaussmeter probes exhibit different ranges of magnetic fields over which they will
provide valid readings. Check the specification sheet for these usable ranges. High Stability
probes, such as those whose model numbers end in -VG, are usable on full scale ranges of
300 gauss (30 millitesla) to 30 kilogauss (3 tesla). The High Sensitivity family of probes
(i.e., -VH models) can be used on 30 G (3 mT) to 30 kG (3 T) full scale ranges. High field probes
are specially calibrated to provide use above 30 kG (3 T), and the Gamma Probe operates on the
300 mG (30 µT) and 3 G (300 µT) ranges.
8. If none of the standard probe configurations seem to fit your needs, always remember that Lake
Shore can provide custom probes to meet your physical, temperature, and accuracy
requirements. Contact Lake Shore with details of your special requirements.
5.2.2
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:
•
•
•
•
Gamma radiation seems to have little effect on the Hall generators.
Proton radiation up to 10 Mrad causes sensitivity changes <0.5%.
Neutron cumulative radiation (>0.1 MeV, 1015/sq. cm.) can cause a 3 to 5% decrease in sensitivity.
In all cases the radiation effects seem to saturate and diminish with length of time exposed.
Accessories and Probes
5-3
Lake Shore Model 421 Gaussmeter User’s Manual
5.2.3
Probe Specifications
Terminology used in Figures 5-1 thru 5-7 are defined as follows:
Definition of Probe Terminology
Usable Full-Scale Ranges Vs. Probe Type
Type
A = Distance from tip to center line of active area
+B = Magnetic flux density vector (for + reading)
HST = High Stability Probe
HSE = High Sensitivity Probe
UHS = Ultra-High Sensitivity Probe
Usable
on
Ranges
HST-1
HST-2
HSE-1
UHS-1
300 G
300 G
30 G
300 mG
3 kG
3 kG
300 G
3G
30 kG
30 kG
3 kG
30 G
300 kG
—
30 kG
—
GAMMA PROBE
L
T
+B
Active Sensing Length 3.125"
Cable Length = 6.6 feet
A
Model No.
W
MLA-5006-HJ
T
A
L
W
To Center of
Active Volume
Frequency
Type
Range
Small variations in, or low values of large volume magnetic fields, such as that
of the Earth or fringe fields, around large solenoids, can be measured with
these ultra-high sensitivity probes. Resolutions of several gammas (10-5 G) to
tens of gammas are available depending on the mating gaussmeter.
Application is optimum when fields are homogeneous over lengths greater
than 1 foot. The active sensing length of the gamma probe is 3.125 inches.
Corrected Operating Temperature Coefficient
(Maximum)
Accuracy Temperature
(% of Reading)
Range
Zero
Calibration
0 °C to
+75 °C
0.25
DC, 10 to
±0.5% to
0.5" 2.2" 5.7"
UHS-1
±0.03"
400 Hz
2 gauss
1 mG/°C
±0.02%/°C
Gamma.eps
Figure 5-1. Definition of Lake Shore Gamma Probe
ROBUST (BRASS STEM) TRANSVERSE PROBES
+B
2.5"
L
S
Cable Length = 6.6 feet
Model
No.
L
MMTB6J02-VH
MMTB6J04-VH
MMTB6J08-VH
MMTB6J02-VG
MMTB6J04-VG
MMTB6J08-VG
2
±0.125"
4
±0.125"
8
±0.125"
2
±0.125"
4
±0.125"
8
±0.125"
S
W
T
A
Active Stem Frequency
Type
Area Material Range
W
T
0.20" dia.
(max.)
0.37" dia.
A
Operating Temperature Coefficient
Corrected
(maximum)
Temperature
Accuracy
Range
(% of Reading)
Zero
Calibration
1.75"
3.5"
to
4"
1.75"
3.5"
to
4"
HSE-1
0.22"
0.061"
0.150"
max
0.040"
Brass
dia.
approx.
±0.25% to
30 kG
±0.09 G/°C ±0.015%/°C
0 °C to
75 °C
DC
HST-2
±0.15% to
30 kG
±0.13 G/°C –0.005%/°C
Brass_Transverse.eps
Figure 5-2. Definition of Lake Shore Robust (Brass Stem) Transverse Probes
5-4
Accessories and Probes
Lake Shore Model 421 Gaussmeter User’s Manual
TRANSVERSE PROBES
+B
L
2.5"
A
W
Cable length = 6.6 feet
Model No.
L
T
MMT-6J02-VH
2 ±0.125"
MMT-6J04-VH* 4 ±0.125"
MMT-6J08-VH
8 ±0.125"
MMT-6J18-VH
18 ±0.25"
T
0.36 ±0.030" dia.
W
Active
Area
A
0.061" 0.180
max. ±0.005"
2 ±0.125" 0.045" 0.150
0.150
MNT-4E04-VH* 4 ±0.125" max. ±0.005"
±
MMT-6J02-VG 2 ±0.125"
0.050"
MMT-6J04-VG* 4 ±0.125" 0.061" 0.180
MMT-6J08-VG 8 ±0.125" max. ±0.005"
MNT-4E02-VH
0.040"
dia.
approx.
Stem
Material
Freq.
Range
Alum.
DC
Rigid
Glass
Epoxy
DC,
10 to
400 Hz
Alum.
DC
MMT-6J18-VG 18 ±0.125"
Rigid
Glass
Epoxy
MNT-4E02-VG* 2 ±0.125" 0.045" 0.150
MNT-4E04-VG 4 ±0.125" max. ±0.005"
MCT-3160-WN
61 ±1"
0.210
±0.050"
0.25 dia.
±0.010"
Stainless
Steel
DC,
10 to
400 Hz
Type
Corrected
Accuracy
(% of rdg)
HSE-1
±0.25%
to
30 kG
Op.
Temp.
Range
Temperature
Coefficient (Max.)
Zero
Calibration
±0.09
Gauss
per °C
±0.015%
per °C
0 °C
to
+75 °C
HST-2
±0.15%
to
30 kG
HST-1
±2% to
100 kG
±0.13
Gauss
per °C
1.5 K to
350 K
–0.005%
per °C
±0.010%
per °C
* One probe is included with the purchase of the Model 421. Model numbers shown in bold are the probes available to choose from.
Transverse.eps
Figure 5-3. Definition of Lake Shore Transverse Probes
TANGENTIAL PROBE
2.5"
L
+B
A
Active Area
0.015 ±0.005"
Cable length = 6.6 feet
Model
No.
L
MNTAN1.5"
DQ02-TH ±0.125"
T
0.125"
max.
T
0.36 ±0.030" dia.
W
0.38"
max.
A
0.030"
±0.005"
Active
Area
Stem
Material
0.020" dia.
approx.
Plastic
Freq.
Range
Type
DC, 10 to
HSE-1
400 Hz
Corrected
Accuracy
(% of rdg)
±0.25%
to 20 kG
W
Op.
Temp.
Range
Temperature
Coefficient (Max.)
Zero
Calibration
0 °C to
±0.1 G/°C –0.05%/°C
+75 °C
Tangential.eps
Figure 5-4. Definition of Lake Shore Tangential Probe
Accessories and Probes
5-5
Lake Shore Model 421 Gaussmeter User’s Manual
AXIAL PROBES
2.5"
L
A
+B
Cable Length = 6.6 feet
Model
L
MMA-0602-TH
2 ±0.125"
MMA-0604-TH
4 ±0.125"
MMA-0608-TH
8 ±0.125"
MMA-0618-TH
18 ±0.125"
MMA-0802-UH
2 ±0.125"
MMA-0804-UH
4 ±0.125"
MMA-0808-UH
8 ±0.125"
MNA-1902-VH
2 ±0.125"
MNA-1904-VH*
4 ±0.125"
MNA-1908-VH
8 ±0.125"
MMA-1802-VH
2 ±0.063"
MMA-1808-VH
8 ±0.125"
MMA-1818-VH
18 ±0.25"
MMA-1836-VH
36 ±0.25"
MMA-2502-VH*
MMA-2508-VH
2 ±0.063" 0.25 dia.
8 ±0.125" ±0.006"
MNA-1902-VG
2 ±0.125"
MNA-1904-VG*
4 ±0.125"
MNA-1908-VG
8 ±0.125"
MMA-1802-VG
2 ±0.063"
MMA-1808-VG
8 ±0.125"
MMA-1818-VG
MMA-1836-VG
MMA-2502-VG*
D
A
0.060
dia.
+0.001
-0.003"
0.005
±
0.003"
0.080"
dia.
0.010"
±0.005"
0.180
dia.
18 ±0.25" +0.002
–0.004"
36 ±0.25"
MMA-2508-VG
MMA-1808-WL
8 ±0.125"
MCA-2560-WN
0.020"
dia.
approx.
Stem
Material
Freq.
Range
Type
DC,
10 to
400 Hz
HST-2
Alum.
±0.25%
to
20 kG
Temp. Coefficient (Max.)
Zero
Calibration
±0.13 G
per °C
±0.01%
per °C
±0.09 G
per °C
±0.015%
per °C
±0.13 G
per °C
–0.005%
per °C
Fiberglass
Epoxy
HSE-1
±0.25%
to
30 kG
HST-2
0.15%
to
30 kG
0 °C
to
75 °C
Alum.
0.030"
dia.
approx.
Fiberglass
Epoxy
DC,
10 to
400 Hz
0.016
±
0.005"
0.180 dia.
+0.002
–0.004"
0.25 dia.
36 ±0.25"
±0.006"
0.25 dia. 0.025
60 ±0.50"
±0.005" ±0.005"
Corrected
Op.
Accuracy Temp.
(% Reading) Range
±0.25%
to
10 kG
DC
0.016
±
0.005"
0.187
dia.
±0.005"
2 ±0.063" 0.25 dia.
8 ±0.125" ±0.006"
MMA-2536-WL
Active
Area
0.187
0.005
dia.
±
±0.005" 0.003"
0.180
dia.
+0.002
-0.004"
D
0.36 ±0.030" dia.
Alum.
HST-1
Stainless
Steel
DC
±1% to
100 kG
±2% to
100 kG
1.5 K to
350 K
±0.010%
per °C
* One probe is included with the purchase of the Model 421. Model numbers shown in bold are the probes available to choose from.
Axial.eps
Figure 5-5. Definition of Lake Shore Axial Probes
5-6
Accessories and Probes
Lake Shore Model 421 Gaussmeter User’s Manual
FLEXIBLE TRANSVERSE PROBES
+B
2.5"
L
S
A
Cable Length = 6.6 feet
0.36 ±0.030" dia.
0.125 ±0.020"
W
T
This table is for L = 3 inches and S = 0.375 inch
Model No.
MFT-3E03-VH
MFT-3E03-VG
MFT-2903-VJ
MFT-2903-VH
W
T
A
0.135" 0.025" 0.125"
max max ±0.005"
0.085" 0.020" 0.065"
max max ±0.005"
Active
Area
0.040"
dia.
approx.
0.030"
dia.
approx.
Stem
Material
Flexible
Tubing
Frequency
Range
DC, 10 to
400 Hz
Type
Corrected
Accuracy
(% of
Reading)
HSE-1
±0.25% to
30 kG
HST-2
±0.15% to
30 kG
HSE-1
±0.50% to
30 kG
HST-2
±0.25% to
30 kG
HSE-1
±0.25% to
30 kG
HST-2
±0.15% to
30 kG
Temperature Coefficient
(maximum)
Operating
Temperature
Range
0 °C to
75 °C
Zero
Calibration
±0.09 G/°C
±0.015%/°C
±0.13 G/°C
–0.005%/°C
±0.09 G/°C
±0.015%/°C
±0.13 G/°C
–0.005%/°C
±0.09 G/°C
±0.015%/°C
±0.13 G/°C
–0.005%/°C
This table is for L = 15 ±0.5 inches and S = 0.75 inch
MFT-4F15-VH
MFT-4F15-VG
0.150" 0.045" 0.150"
±0.005" max ±0.050"
0.040"
dia.
approx.
Flexible
Tubing
& Epoxy
Fiberglass
DC, 10 to
400 Hz
0 °C to
75 °C
Flexible_Transverse.eps
Figure 5-6. Definition of Lake Shore Flexible Transverse Probes
FLEXIBLE AXIAL PROBE
2.5"
L
A
+B
Cable Length = 6.6 feet
Model No.
MFA-1815-VH
L
D
A
0.36 ±0.030" dia.
Active
Area
15" 0.025" 0.125" 0.040" dia.
±0.5" max ±0.005" approx.
0.125 ±0.020"
Stem
Material
Frequency
Range
Type
Flexible
Tubing
DC, 10 to
400 Hz
HSE-1
1"
D
Operating Temperature Coefficient (max.)
Corrected
Temperature
Accuracy
Calibration
Zero
Range
(% of Reading)
±0.25% to
30 kG
0 °C to
75 °C
±0.09 G/°C
±0.015%/°C
Flexible_Axial.eps
Figure 5-7. Definition of Lake Shore Flexible Axial Probe
Accessories and Probes
5-7
Lake Shore Model 421 Gaussmeter User’s Manual
5.3
HELMHOLTZ COIL LOW FIELD STANDARDS
Lake Shore offers three Helmholtz coils: 2.5-, 6-, and 12-inch diameter. Check the latest Lake Shore
brochures or our website for any recent additions to this line.
These coils are accurately calibrated using field standards maintained at Lake Shore. Most standards
are traceable to physical standards such as a coil of carefully controlled dimensions, or in some cases,
to proton resonance. The field strengths are measured on the basis of the field generated by a current
through the coil.
When combined with a customer-supplied power supply, these coils can be used as low-field reference
magnets to compliment our set of standard reference magnets (defined in Paragraph 5.4). The power
supply must be capable of 2 A output and a constant-current mode is recommended.
MH-2.5
2.5 inches
Inside Diameter
Field Accuracy
MH-6
6 inches
MH-12
12 inches
±0.5%
Field Strength
Field Homogeneity
Coil Resistance/Inductance
≈30 G @ 1 A
≈25 G @ 1 A
≈12 G @ 1 A
0.5% within a
cylindrical volume
0.75" long, 0.75"
diameter, located at
center of coil
0.5% within a
cylindrical volume
1.6" long, 1.6"
diameter, located at
center of coil
0.5% within a
cylindrical volume
3.2" long, 3.2"
diameter, located at
center of coil
≈3 Ω / 6.3 mH
≈10 Ω / 36 mH
≈20 Ω / 93 mH
Maximum Continuous Current
2 A DC or AC RMS
Operating Temperature Range
10 to 40 °C (50 to 104 °F)
P-421-5-08.bmp
Figure 5-8. Model MH-2.5 Helmholtz Coil
5-8
Accessories and Probes
Lake Shore Model 421 Gaussmeter User’s Manual
P-421-5-09.bmp
Figure 5-9. Model MH-6 Helmholtz Coil
P-421-5-10.bmp
Figure 5-10. Model MH-12 Helmholtz Coil
Accessories and Probes
5-9
Lake Shore Model 421 Gaussmeter User’s Manual
5.4
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. They are supplied in both transverse (flat) and axial configurations.
Typical flat reference magnets are usually stabilized for use at ambient temperatures between
0 – 50 °C and have nominal temperature coefficients of about –0.02%/°C. Because the temperature
coefficient is negative, the field strength will be reduced as the temperature rises. Since these
references are temperature cycled during manufacture, their change with temperature is predictable
and retraceable; they will always return to a known value at any specific ambient temperature.
The high-permeability shell which surrounds the reference magnet serves two function: (1) it shields the
magnet from external field, and (2) serves as the flux return path. Physical damage to the outer shell
can cause a permanent change in the gap flux density. Reference magnets should not be dropped or
physically abused. Magnets of this type can have magnetic reference values ranging from 100 G to
20 kG, but the most widely-used value is 1 kG. Reference magnets accuracy is typically ±0.5%, except
for magnets of 200 G or less; for these magnets, the limit of error is generally ±1%. The reference
magnet gap is nominally 0.060 inch but may range from 0.040 to 0.250 inch for special units. The
usable "plateau" in the reference gap generally encompasses an area of about 0.5 square inches.
In reference magnets used for axial field probes, Alnico V or VI is the usual magnet material, charged to
saturation and stabilized down to a particular value. The same temperature coefficients hold true as in
the transverse probe and the same care in handling must be observed. This assembly uses concentric
mu-metal shield cans to protect the magnet from the effects of external magnetic field. Axial reference
magnets are available in values up to 1 kG, with 500 G being the most widely-used value.
When a probe is inserted completely through the access guide, three distinct magnetic peaks will be
observed on the gaussmeter. One peak occurs as the probe enters the magnet, a second (and greater)
peak is observed as the midpoint is reached, and a third (smaller) peak is read as the probe leaves the
magnet. The calibration point is the largest reading in the midpoint area. Its amplitude will be
approximately twice that of the readings that occur where the probe enters or leaves the magnet.
P-421-5-11.bmp
Figure 5-11. Lake Shore Reference Magnets
5-10
Accessories and Probes
Lake Shore Model 421 Gaussmeter User’s Manual
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. If no professional degausser is available,
a bulk tape degausser (Verity VS250, Data Devices PF211, or equivalent) may be used.
Front View
Side View
32.2 mm
(1.3 in.)
61 mm (2.4 in.)
32.2 mm
(1.3 in)
12.2 mm (0.5 in.) diameter
by 50.8 mm (2 in.) deep bore
4060_Chamber.eps
Figure 5-12. Model 4060 Zero Gauss Chamber
Front View
57.2 mm
(2.3 in)
19 mm (0.8 in)
diameter opening
31.8 mm
(1.3 in)
52.4 mm
(2.1 in)
304.8 mm (12 in.)
(Depth of Opening) 279.4 mm (11 in.)
Side View
4065_Chamber.eps
Figure 5-13. Model 4065 Large Zero Gauss Chamber
Accessories and Probes
5-11
Lake Shore Model 421 Gaussmeter User’s Manual
5
6
1
Refer to
“Note”
4
2
NOTE
5
Customer must use 5/64" (2 mm)
hex key to remove four existing
screws from sides of instrument.
3
Unit on right side mounting shown.
Unit on left side also possible.
6
6
4
Item
Description
P/N
Qty
1
Rack Mount Ear
107-440
1
2
Rack Mount Support
107-442
1
3
Rack Mount Panel
107-432
1
4
Rack Mount Handle
107-051-01
2
5
Screw, 6-32 × 1/2 Inch
0-035
4
0-081
6
FHMS Phillips
6
Screw, 8-32 × 3/8 Inch
FHMS Phillips
RM12_Rack.eps
Figure 5-14. Model RM-1/2 Rack-Mount Kit
5-12
Accessories and Probes
Lake Shore Model 421 Gaussmeter User’s Manual
Refer to
“Installation
Procedure”
Installation Procedure
1.
Use 5/64 inch (2 mm) hex key to remove two 6-32 x 1/4
black button head screws from side of Gaussmeter.
2.
Place Gaussmeter on shelf.
3.
Use 5/64 inch (2 mm) hex key to reinstall two 6-32 x 1/4
black button head screws through side of rack into
corresponding holes in the side of the Gaussmeter.
RM2_Dual_Rack.eps
Figure 5-15. Model RM-2 Dual Rack-Mount Shelf
Accessories and Probes
5-13
Lake Shore Model 421 Gaussmeter User’s Manual
This Page Intentionally Left Blank
5-14
Accessories and Probes
Lake Shore Model 421 Gaussmeter User’s Manual
CHAPTER 6
SERVICE
6.0
GENERAL
This chapter provides general service and calibration information for the Lake Shore Model 421
Gaussmeter. General maintenance precautions are described in Paragraph 6.1, electrostatic discharge
in Paragraph 6.2, line voltage selection in Paragraph 6.3, fuse replacement in Paragraph 6.4, rear
panel connector definitions in Paragraph 6.5, top of enclosure remove and replace procedure in
Paragraph 6.6, EPROM replacement in Paragraph 6.7, and error messages in Paragraph 6.8.
There are no field serviceable parts inside the Model 421. Contact Lake Shore about specific problems
with the Model 421.
6.1
GENERAL MAINTENANCE PRECAUTIONS
Below are general safety precautions unrelated to any other procedure in this publication. These are
recommended precautions that personnel should understand and apply during the maintenance phase.
Keep away from live circuits. Installation personnel shall observe all safety regulations at all times. Turn
off system power before making or breaking electrical connections. Regard any exposed connector,
terminal board, or circuit board as a possible shock hazard. Discharge charged components only when
such grounding results in no equipment damage. If a test connection to energized equipment is
required, make the test equipment ground connection before probing the voltage or signal to be tested.
Do not install or service equipment alone. Do not reach into or adjust the equipment without having
another person nearby capable of rendering aid.
If there is no power, verify the power cord is plugged into a live outlet and that both ends are securely
plugged in. Next, check the fuse.
Use this procedure to periodically clean the Model 421 to remove dust, grease, and other contaminants:
1. Clean front and back panels and case with soft cloth dampened with a mild detergent and water
solution.
NOTE: Do not use aromatic hydrocarbons or chlorinated solvents to clean the Model 421.
They may react with the plastic materials used in the controller or the silk screen
printing on the back panel.
2. Clean the surface of printed circuit boards (PCBs) with clean, dry air at low pressure.
6.2
ELECTROSTATIC DISCHARGE
Electrostatic Discharge (ESD) may damage electronic parts, assemblies, and equipment. ESD is a
transfer of electrostatic charge between bodies at different electrostatic potentials caused by direct
contact or induced by an electrostatic field. The low-energy source that most commonly destroys
Electrostatic Discharge Sensitive (ESDS) devices is the human body, which generates and retains
static electricity. Simply walking across a carpet in low humidity may generate up to 35,000 volts of
static electricity.
Current technology trends toward greater complexity, increased packaging density, and thinner
dielectrics between active elements, which results in electronic devices with even more ESD sensitivity.
Some electronic parts are more ESDS than others. ESD levels of only a few hundred volts may
damage electronic components such as semiconductors, thick and thin film resistors, and piezoelectric
crystals during testing, handling, repair, or assembly. Discharge voltages below 4000 volts cannot be
seen, felt, or heard.
Service
6-1
Lake Shore Model 421 Gaussmeter User’s Manual
6.2.1
Identification of Electrostatic Discharge Sensitive Components
Below are various industry symbols used to label components as ESDS:
6.2.2
Handling Electrostatic Discharge Sensitive Components
Observe all precautions necessary to prevent damage to ESDS components before attempting
installation. Bring the device and everything that contacts it to ground potential by providing a
conductive surface and discharge paths. As a minimum, observe these precautions:
1. De-energize or disconnect all power and signal sources and loads used with unit.
2. Place unit on a grounded conductive work surface.
3. Ground technician through a conductive wrist strap (or other device) using 1 MΩ series resistor to
protect operator.
4. Ground any tools, such as soldering equipment, that will contact unit. Contact with operator's
hands provides a sufficient ground for tools that are otherwise electrically isolated.
5. Place ESDS devices and assemblies removed from a unit on a conductive work surface or in a
conductive container. An operator inserting or removing a device or assembly from a container
must maintain contact with a conductive portion of the container. Use only plastic bags approved
for storage of ESD material.
6. Do not handle ESDS devices unnecessarily or remove from the packages until actually used or
tested.
6.3
LINE VOLTAGE SELECTION
Use the following procedure to change the instrument line voltage selector. Verify the fuse value
whenever line voltage is changed.
WARNING: To avoid potentially lethal shocks, turn off controller and disconnect it from AC
power before performing these procedures.
1. Identify the line input assembly on the instrument rear panel. See Figure 6-1.
2. Turn the line power switch OFF (O).
3. Remove the instrument power cord.
4. With a small screwdriver, release the drawer holding the line voltage selector and fuse.
5. Slide out the removable plastic fuse holder from the drawer.
6. Rotate the fuse holder until the proper voltage indicator shows through the window.
7. Verify the proper fuse value.
8. Re-assemble the line input assembly in the reverse order.
9. Verify the voltage indicator in the window of the line input assembly.
10. Connect the instrument power cord.
11. Turn the line power switch On (l).
6-2
Service
Lake Shore Model 421 Gaussmeter User’s Manual
Power Switch
O=Off, l=On
Line Cord
Input
Screwdriver
Slot
Fuse
Drawer
120
100/120/220/240 V
–10% +6% Voltage 100/120V 0.5 A T 250V 0.25×1.25"
50-60 Hz 40 VA MAX 220/240V 0.25 A T 250V 5×20mm
F-421-6-1.eps
Figure 6-1. Power Fuse Access
6.4
FUSE REPLACEMENT
Below is the procedure to remove and replace a line fuse. There are two basic power configurations:
U.S. and International. Units produced for use in the U.S. have a single fuse on the hot. Units produced
for International use have a double fuse for the hot and neutral. To change line input from the factory
setting, use the appropriate fuse in the connector kit shipped with the instrument. Test fuse with
ohmmeter. Do not rely on visual inspection of fuse.
WARNING: To avoid potentially lethal shocks, turn off controller and disconnect it from AC
power before performing these procedures.
CAUTION: For continued protection against fire hazard, replace only with the same fuse type and
rating specified for the line for the line voltage selected.
1. Locate line input assembly on the instrument rear panel. See Figure 6-1.
2. Turn power switch Off (O).
3. Remove instrument power cord.
4. With a small screwdriver, release the drawer holding the line voltage selector and fuse.
5. Remove existing fuse(s). Replace with proper Slow-Blow fuse ratings as follows:
100/120 V
0.5 A T 250 V
0.25 × 1.25 inches
220/240 V
0.25 A T 250 V
5 × 20 mm
6. Re-assemble line input assembly in reverse order.
7. Verify voltage indicator in the line input assembly window.
8. Connect instrument power cord.
9. Turn power switch On (l).
Service
6-3
Lake Shore Model 421 Gaussmeter User’s Manual
6.5
REAR PANEL CONNECTOR DEFINITIONS
The connectors on the rear panel of the Model 421 Gaussmeter are detailed in Figures 6-2 thru 6-5.
Additional details for various external serial cables are provided in Paragraphs 6.5 1.
PROBE INPUT
8
7
15
6
14
5
13
4
12
3
11
2
1
10
9
CAUTION: POWER OFF TO MATE PROBE
View Looking At Rear
Of Model 421
C-480-6-2.eps
PIN
DESCRIPTION
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Input + (Analog Signal)
No Connection
No Connection
No Connection
No Connection
No Connection
No Connection
IC +
Input - (Analog Signal Ground)
No Connection
Digital Ground
+5 Volts (Power Output To Probe EEPROM)
EE-CLK (Output To Probe EEPROM)
EE-DATA (Serial Input From Probe EEPROM)
IC -
Figure 6-2. PROBE INPUT Connector Details
ANALOG OUTPUTS
Corrected
Monitor
C-421-6-3.eps
PIN
1
2
DESCRIPTION
Analog Output – Center Conductor
Ground – Connector Shell
Figure 6-3. Corrected and Monitor ANALOG OUTPUTS Connector Details
6-4
Service
Lake Shore Model 421 Gaussmeter User’s Manual
Slides into RELAY slot
at rear of Model 421
Use screwdriver to
lock or unlock wires
Terminal Block Connector
Lake Shore P/N 106-741
NO
NC C
Insert wire
into slot
C-421-6-4.eps
PIN
1
2
3
DESCRIPTION
Normally Closed (NC)
Common (C)
Normally Open (NO)
Figure 6-4. RELAY Terminal Block Details
SERIAL I/O (DTE)
5
4
9
3
8
2
7
1
6
View Looking At Rear
Of Model 421
C-421-6-5.eps
Model 421 Gaussmeter (DTE)
DE-9P
Computers and Printers (DTE)
DB-25P
DE-9P
Pin
Description
Pin
Description
Pin
Description
1
2
3
4
5
6
7
8
9
No Connection
Receive Data (RD in)
Transmit Data (TD out)
Data Terminal Ready (DTR out)
Ground (GND)
Data Set Ready (DSR in)
Data Terminal Ready (DTR out) (tied to 4)
No Connection
No Connection
2
3
4
5
6
7
8
20
22
TD (out)
RD (in)
RTS (out)
CTS (in)
DSR (in)
GND
DCD (in)
DTR (out)
Ring in (in)
1
2
3
4
5
6
7
8
9
DCD (in)
RD (in)
TD (out)
DTR (out)
GND
DSR (in)
RTS (out)
CTS (in)
Ring in (in)
Figure 6-5. SERIAL I/O (DTE) Connector Details
Service
6-5
Lake Shore Model 421 Gaussmeter User’s Manual
6.5.1
Serial Interface Cable Wiring
The following are suggested cable wiring diagrams for connecting the Model 421 Serial Interface to
various Customer Personal Computers (PCs).
Model 421 to PC Serial Interface – PC with DE-9P
Model 421 DE-9P
Standard Null-Modem Cable (DE-9S to DE-9S)
5 - GND
2 - RD (in)
3 - TD (out)
4 - DTR (out)
6 - DSR (in)
1 - NC
7 - DTR (tied to 4)
8 - NC
PC DE-9P
5 - GND
3 - TD (out)
2 - RD (in)
6 - DSR (in)
4 - DTR (out)
7 - RTS (out)
8 - CTS (in)
1 - DCD (in)
Model 421 to PC Serial Interface – PC with DE-25P
Model 421 DE-9P
Standard Null-Modem Cable (DE-9S to DB-25S)
5 - GND
2 - RD (in)
3 - TD (out)
1 - NC
7 - DTR (tied to 4)
8 - NC
6 - DSR (in)
4 - DTR (out)
PC DB-25P
7 - GND
2 - TD (out)
3 - RD (in)
4 - RTS (out)
5 - CTS (in)
8 - DCD (in)
20 - DTR (out)
6 - DSR (in)
Model 421 to PC Interface using Null Modem Adapter
Model 421 DE-9P
5 - GND
2 - RD (in)
3 - TD (out)
1 - NC
6 - DSR (in)
4 - DTR (out)
7 - DTR (tied to 4)
8 - NC
9 - NC
Null Modem Adapter
PC DE-9P
5 - GND
3 - TD (out)
2 - RD (in)
4 - DTR (out)
1 - DCD (in)
6 - DSR (in)
8 - CTS (in)
7 - RTS (out)
9 - NC
NOTE: Same as null modem cable design except PC CTS is provided from the
Model 421 on DTR.
6-6
Service
Lake Shore Model 421 Gaussmeter User’s Manual
6.6
TOP OF ENCLOSURE REMOVAL AND REPLACEMENT
WARNING: To avoid potentially lethal shocks, turn off gaussmeter and disconnect it from
AC power line before performing this procedure. Only qualified personnel
should perform this procedure.
6.6.1
Removal Procedure
1. Turn power switch Off (O).
2. Remove instrument power cord.
3. If attached, remove rack mounting brackets.
4. Use 5/64 hex key to remove four screws attaching top panel to unit.
5. Use 5/64 hex key to loosen two rear screws attaching bottom panel to unit.
6. Carefully remove the back bezel by sliding it straight back away from the unit.
7. Slide the top panel back and remove it from the unit.
6.6.2
Installation Procedure
1. Slide the top panel forward in the track provided on each side of the unit.
2. Carefully replace the back bezel by sliding it straight into the unit.
3. Use 5/64 hex key to install four screws attaching top panel to unit.
4. Use 5/64 hex key to tighten two rear screws attaching bottom panel to unit.
5. If required, reattach rack mounting brackets.
6. Attach instrument power cord.
7. Turn power switch On (l).
6.7
EPROM REPLACEMENT
The operating software for the Model 421 is contained on one Erasable Programmable Read Only
Memory (EPROM) Integrated Circuit (IC). The reference designator for the EPROM is U36, Lake Shore
Part Number 113-591. The EPROM has a sticker on top labeled with “M421.HEX” and the date. Use
the following procedure to replace the EPROM.
CAUTION: The EPROM is an Electrostatic Discharge Sensitive (ESDS) device. Wear shock-proof
wrist straps (with a resistor that limits current to <5 mA) to prevent injury to service
personnel and to avoid inducing an Electrostatic Discharge (ESD) into the device. Refer to
Paragraph 6.2.
1. Follow the top of enclosure REMOVAL procedure in Paragraph 6.6.1.
2. Remove four phillips-head screws attaching transformer bracket to the Model 421 chassis.
Carefully pull transformer bracket up and sufficiently out of the way to gain access to the
Operating Software EPROM. See Figure 6-6.
3. Locate EPROM U36 (M421.HEX) on the main circuit board. Note orientation of existing IC.
Match notch on
EPROM to notch
in socket
M421.HEX
113-591
02.03.99
1
Typical EPROM
eprom.eps
4. Use IC puller to remove existing EPROM from socket.
5. Noting orientation of new EPROM, use an IC insertion tool to place new device into socket.
6.
Install four phillips-head screws attaching transformer bracket to the Model 421 chassis.
7.
Follow the top of enclosure INSTALLATION procedure in Paragraph 6.6.2.
Service
6-7
Lake Shore Model 421 Gaussmeter User’s Manual
Front
Operating Software
EPROM (U36)
Refer to Paragraph 6.7
JMP2
Rear
Corrected Analog Output (JMP2)
3V position is for ±3V = ±Full Scale
10V position is for ±10V = ±Full Scale
Must be in 3V position for rated accuracy.
Changing to 10V requires instrument be recalibrated.
Contact Lake Shore for details.
3V
10V
U36
Fuse
Transformer
Power Inlet
C-421-6-6.eps
Figure 6-6. Location of Operation Software EPROM and Analog Output Jumper
6.8
ERROR MESSAGES
The following is a list of Model 421 error messages that may be seen during normal operation.
6-8
OL
Field range has been exceeded. Refer to Paragraph 3.5 to change Range.
** No Probe **
No probe attached to the instrument at power up. Power the instrument off, attach a
probe, and power it on again.
Locked
Keypad is locked to prevent accidental parameter changes. To unlock keypad refer
to Paragraph 3.13.
Error 1
NOVRAM memory is physically malfunctioning. Contact Lake Shore service for
repair.
Error2
NOVRAM memory is not initialized properly. Memory can be reinitialized as
described in Paragraph 3.15. This operation will not restore calibration data that may
have been corrupted. Instrument calibration should be checked after any Error 2
condition. Contact Lake Shore service for repair or calibration.
Service
Lake Shore Model 421 Gaussmeter User’s Manual
APPENDIX A
GLOSSARY OF TERMINOLOGY
2
accuracy. The degree of correctness with which a measured value agrees with the true value.
electronic accuracy. The accuracy of an instrument independent of the sensor.
sensor accuracy. The accuracy of a Hall generator and its associated calibration.
American Standard Code for Information Exchange (ASCII). A standard code used in data transmission, in which
128 numerals, letters, symbols, and special control codes are represented by a 7-bit binary number as follows:
American Wire Gage (AWG). Wiring sizes are defined as diameters in inches and millimeters as follows:
AWG
Dia. In.
Dia. mm
1
2
3
4
5
6
7
8
9
10
0.2893
0.2576
0.2294
0.2043
0.1819
0.1620
0.1443
0.1285
0.1144
0.1019
7.348
6.544
5.827
5.189
4.621
4.115
3.665
3.264
2.906
2.588
AWG
Dia. In.
Dia. mm
11
12
13
14
15
16
17
18
19
20
0.0907
0.0808
0.0720
0.0641
0.0571
0.0508
0.0453
0.0403
0.0359
0.0338
2.304
2.053
1.829
1.628
1.450
1.291
1.150
1.024
0.9116
0.8118
AWG
Dia. In.
Dia. mm
21
22
23
24
25
26
27
28
29
30
0.0285
0.0253
0.0226
0.0207
0.0179
0.0159
0.0142
0.0126
0.0113
0.0100
0.7230
0.6438
0.5733
0.5106
0.4547
0.4049
0.3606
0.3211
0.2859
0.2546
AWG
Dia. In.
Dia. mm
31
32
33
34
35
36
37
38
39
40
0.0089
0.0080
0.00708
0.00630
0.00561
0.00500
0.00445
0.00397
0.00353
0.00314
0.2268
0.2019
0.178
0.152
0.138
0.127
0.1131
0.1007
0.08969
0.07987
ampere. The constant current that, if maintained in two straight parallel conductors of infinite length, of negligible circular
cross section, and placed one meter apart in a vacuum, would produce between these conductors a force equal to
–7
2
2 × 10 newton per meter of length. This is one of the base units of the SI.
ampere-turn. A MKS unit of magnetomotive force equal to the magnetomotive force around a path linking one turn of a
conducting loop carrying a current of one ampere; or 1.26 gilberts.
ampere/meter (A/m). The SI unit for magnetic field strength (H). 1 ampere/meter = 4π/1000 oersted ≈0.01257 oersted.
1
analog data. Data represented in a continuous form, as contrasted with digital data having discrete values.
analog output. A voltage output from an instrument that is proportional to its input. From an instrument such as a digital
voltmeter, the output voltage is generated by a digital-to-analog converter with a discrete number of voltage levels.
anode. The terminal that is positive with respect to the other terminal when the diode is biased in the forward direction.2
Cathode –
+ Anode
area. A measure of the size of a two-dimensional surface, or of a region on such a surface.1
area·turns. A coil parameter produced by the multiplication of a magnet's area and number of turns. Gives an indication
of the sensitivity of a coil.
B. Symbol for magnetic flux density. See Magnetic Flux Density.
baud. A unit of signaling speed equal to the number of discrete conditions or signal events per second, or the reciprocal
2
of the time of the shortest signal element in a character.
2
bit. A contraction of the term “binary digit”; a unit of information represented by either a zero or a one.
calibration. To determine, by measurement or comparison with a standard, the correct (accurate) value of each scale
reading on a meter or other device, or the correct value for each setting of a control knob.1
Glossary of Terminology
A-1
Lake Shore Model 421 Gaussmeter User’s Manual
cathode. The terminal from which forward current flows to the external circuit.2
Cathode –
+ Anode
Celsius (°C) Scale. A temperature scale that registers the freezing point of water as 0 °C and the boiling point as 100 °C
under normal atmospheric pressure. Celsius degrees are purely derived units, calculated from the Kelvin
Thermodynamic Scale. Formerly known as “centigrade.” See Temperature for conversions.
2
cgs system of units. A system in which the basic units are the centimeter, gram, and second.
coercive force (coercive field). The magnetic field strength (H) required to reduce the magnetic induction (B) in a
magnetic material to zero.
coercivity. generally used to designate the magnetic field strength (H) required to reduce the magnetic induction (B) in a
magnetic material to zero from saturation. The coercivity would be the upper limit to the coercive force.
compliance voltage. See current source.
Curie temperature (Tc). Temperature at which a magnetized sample is completely demagnetized due to thermal
agitation. Named for Pierre Curie (1859 – 1906), a French chemist.
current source. A type of power supply that supplies a constant current through a variable load resistance by
automatically varying its compliance voltage. A single specification given as “compliance voltage” means the output
current is within specification when the compliance voltage is between zero and the specified voltage.
demagnetization. when a sample is exposed to an applied field (Ha), poles are induced on the surface of the sample.
Some of the returned flux from these poles is inside of the sample. This returned flux tends to decrease the net
magnetic field strength internal to the sample yielding a true internal field (Hint) given by: Hint = Ha – DM ,where M is the
volume magnetization and D is the demagnetization factor. D is dependent on the sample geometry and orientation with
respect to the field.
deviation. The difference between the actual value of a controlled variable and the desired value corresponding to the
setpoint.1
differential permeability. The slope of a B versus H curve: µd = dB/dH.
differential susceptibility. The slope of a M versus H curve: χd = dM/dH.
digital controller. A feedback control system where the feedback device (sensor) and control actuator (heater) are joined
by a digital processor. In Lake Shore controllers the heater output is maintained as a variable DC current source.
2
digital data. Pertaining to data in the form of digits or interval quantities. Contrast with analog data.
dimensionless sensitivity. Sensitivity of a physical quantity to a stimulus, expressed in dimensionless terms. The
dimensionless temperature sensitivity of a resistance temperature sensor is expressed as Sd = (T/R)(dR/dT) which is
also equal to the slope of R versus T on a log-log plot, that is Sd = d lnR / d lnT. Note that the absolute temperature (in
kelvin) must be used in these expressions.
drift, instrument. An undesired but relatively slow change in output over a period of time, with a fixed reference input.
Note: Drift is usually expressed in percent of the maximum rated value of the variable being measured.2
electromagnet. A device in which a magnetic field is generated as the result of electrical current passing through a helical
conducting coil. It can be configured as an iron-free solenoid in which the field is produced along the axis of the coil, or
an iron-cored structure in which the field is produced in an air gap between pole faces. The coil can be water cooled
copper or aluminum, or superconductive.
electron. An elementary particle containing the smallest negative electric charge. Note: The mass of the electron is
2
approximately equal to 1/1837 of the mass of the hydrogen atom.
electrostatic discharge (ESD). A transfer of electrostatic charge between bodies at different electrostatic potentials
caused by direct contact or induced by an electrostatic field.
error. Any discrepancy between a computed, observed, or measured quantity and the true, specified, or theoretically
2
correct value or condition.
Fahrenheit (°F) Scale. A temperature scale that registers the freezing point of water as 32 °F and the boiling point as
212 °F under normal atmospheric pressure. See Temperature for conversions.
1
flux (φ). The electric or magnetic lines of force in a region.
flux density (B). Any vector field whose flux is a significant physical quantity; examples are magnetic flux density, electric
1
displacement, and gravitational field.
gamma. A cgs unit of low-level flux density, where 100,000 gamma equals one oersted, or 1 gamma equals 10–5 oersted.
gauss (G). The cgs unit for magnetic flux density (B). 1 gauss = 10–4 tesla = 1 Mx/cm2 = line/cm2. Named for Karl Fredrich
Gauss (1777 – 1855) a German mathematician, astronomer, and physicist.
gaussian system (units). A system in which centimeter-gram-second units are used for electric and magnetic qualities.
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 10/4π ampere-turn. Named for William Gilbert (1540 – 1603),
an English physicist; hypothesized that the earth is a magnet.
gilbert per centimeter. Practical cgs unit of magnet intensity. Gilberts per cm are the same as oersteds.
A-2
Glossary of Terminology
Lake Shore Model 421 Gaussmeter User’s Manual
Greek alphabet. The Greek alphabet is defined as follows:
Alpha
Beta
Gamma
Delta
Epsilon
Zeta
Eta
Theta
α
β
γ
δ
ε
ζ
η
θ
Α
Β
Γ
∆
Ε
Ζ
Η
Θ
Iota
Kappa
Lambda
Mu
Nu
Xi
Omicron
Pi
ι
κ
λ
µ
ν
ξ
ο
π
Ι
Κ
Λ
Μ
Ν
Ξ
Ο
Π
Rho
Sigma
Tau
Upsilon
Phi
Chi
Psi
Omega
ρ
σ
τ
υ
φ
χ
ψ
ω
Ρ
Σ
Τ
Υ
Φ
Χ
Ψ
Ω
ground. A conducting connection, whether intentional or accidental, by which an electric circuit or equipment is connected
to the earth, or to some conducting body of large extent that serves in place of the earth. Note: It is used for establishing
and maintaining the potential of the earth (or of the conducting body) or approximately that potential, on conductors
connected to it, and for conducting ground current to and from the earth (or of the conducting body).2
H. Symbol for magnetic field strength. See Magnetic Field Strength.
Hall effect. The generation of an electric potential perpendicular to both an electric current flowing along a thin conducting
material and an external magnetic field applied at right angles to the current. Named for Edwin H. Hall (1855 – 1938), an
American physicist.
Hall mobility. The quantity µH in the relation µH = Rσ, where R = Hall coefficient and σ = conductivity.2
Helmholtz coils. A pair of flat, circular coils having equal numbers of turns and equal diameters, arranged with a common
1
axis, and connected in series; used to obtain a magnetic field more nearly uniform than that of a single coil.
hertz (Hz). A unit of frequency equal to one cycle per second.
hole. A mobile vacancy in the electronic valence structure of a semiconductor that acts like a positive electron charge with
a positive mass.2
hysteresis. The dependence of the state of a system on its previous history, generally in the form of a lagging of a
physical effect behind its cause.1 Also see magnetic hysteresis.
IEEE. Institute of Electrical and Electronics Engineers.
IEEE-488. An instrumentation bus with hardware and programming standards designed to simplify instrument interfacing.
The addressable, parallel bus specification is defined by the IEEE.
initial permeability. The permeability determined at H = 0 and B = 0.
initial susceptibility. The susceptibility determined at H = 0 and M = 0.
integrator. A circuit or network whose output waveform is the time integral of its input waveform.1
international system of units (SI). A universal coherent system of units in which the following seven units are
considered basic: meter, kilogram, second, ampere, kelvin, mole, and candela. The International System of Units, or
Système International d'Unités (SI), was promulgated in 1960 by the Eleventh General Conference on Weights and
Measures. For definition, spelling, and protocols, see Reference 3 for a short, convenient guide.
interpolation table. A table listing the output and sensitivity of a sensor at regular or defined points which may be
different from the points at which calibration data was taken.
intrinsic coercivity. The magnetic field strength (H) required to reduce the magnetization (M) or intrinsic induction in a
magnetic material to zero.
intrinsic induction. The contribution of the magnetic material (Bi) to the total magnetic induction (B).
Bi = B – H (cgs)
Bi = B – µo H (SI)
isolated (neutral system). A system that has no intentional connection to ground except through indicating, measuring, or
2
protective devices of very-high impedance.
Kelvin (K). The unit of temperature on the Kelvin Scale. It is one of the base units of SI. The word “degree” and its symbol
(°) are omitted from this unit. See Temperature Scale for conversions.
Kelvin Scale. The Kelvin Thermodynamic Temperature Scale is the basis for all international scales, including the ITS-90.
It is fixed at two points: the absolute zero of temperature (0 K), and the triple point of water (273.16 K), the equilibrium
temperature that pure water reaches in the presence of ice and its own vapor.
line regulation. The maximum steady-state amount that the output voltage or current will change as the result of a
specified change in input line voltage (usually for a step change between 105 – 125 or 210 – 250 volts, unless otherwise
specified).
line of flux. An imaginary line in a magnetic field of force whose tangent at any point gives the direction of the field at that
point; the lines are spaced so that the number through a unit area perpendicular to the field represents the intensity of
the field. Also know as a Maxwell in the cgs system of units.
line voltage. The RMS voltage of the primary power source to an instrument.
load regulation. A steady-state decrease of the value of the specified variable resulting from a specified increase in load,
generally from no-load to full-load unless otherwise specified.
M. Symbol for magnetization. See magnetization.
Glossary of Terminology
A-3
Lake Shore Model 421 Gaussmeter User’s Manual
magnetic air gap. The air space, or non-magnetic portion, of a magnetic circuit.
magnetic field strength (H). The magnetizing force generated by currents and magnetic poles. For most applications,
the magnetic field strength can be thought of as the applied field generated, for example, by a superconducting magnet.
The magnetic field strength is not a property of materials. Measure in SI units of A/m or cgs units of oersted.
magnetic flux density (B). Also referred to as magnetic induction. This is the net magnetic response of a medium to an
applied field, H. The relationship is given by the following equation: B = µo(H + M) for SI, and B = H + 4πM for cgs,
–7
where H = magnetic field strength, M = magnetization, and µo = permeability of free space = 4π × 10 H/m.
magnetic hysteresis. The property of a magnetic material where the magnetic induction (B) for a given magnetic field
strength (H) depends upon the past history of the samples magnetization.
magnetic induction (B). See magnetic flux density.
magnetic moment (m). This is the fundamental magnetic property measured with dc magnetic measurements systems
such as a vibrating sample magnetometer, extraction magnetometer, SQUID magnetometer, etc. The exact technical
definition relates to the torque exerted on a magnetized sample when placed in a magnetic field. Note that the moment
is a total attribute of a sample and alone does not necessarily supply sufficient information in understanding material
properties. A small highly magnetic sample can have exactly the same moment as a larger weakly magnetic sample
(see Magnetization). Measured in SI units as A·m2 and in cgs units as emu. 1 emu = 10–3 A·m2.
magnetic scalar potential. The work which must be done against a magnetic field to bring a magnetic pole of unit
strength from a reference point (usually at infinity) to the point in question. Also know as magnetic potential.1
magnetic units. Units used in measuring magnetic quantities. Includes ampere-turn, gauss, gilbert, line of force, maxwell,
oersted, and unit magnetic pole.
magnetization (M). This is a material specific property defined as the magnetic moment (m) per unit volume (V).
3
3
3
M = m/V. Measured in SI units as A/m and in cgs units as emu/cm . 1 emu/cm = 10 A/m. Since the mass of a sample
is generally much easier to determine than the volume, magnetization is often alternately expressed as a mass
magnetization defined as the moment per unit mass.
magnetostatic. Pertaining to magnetic properties that do not depend upon the motion of magnetic fields.1
mains. See line voltage.
Maxwell (Mx). A cgs electromagnetic unit of magnetic flux, equal to the magnetic flux which produces an electromotive
force of 1 abvolt in a circuit of one turn link the flux, as the flux is reduced to zero in 1 second at a uniform rate.1
MKSA System of Units. A system in which the basic units are the meter, kilogram, and second, and the ampere is a
derived unit defined by assigning the magnitude 4π × 10–7 to the rationalized magnetic constant (sometimes called the
permeability of space).
NBS. National Bureau of Standards. Now referred to as NIST.
National Institute of Standards and Technology (NIST). Government agency located in Gaithersburg, Maryland and
Boulder, Colorado, that defines measurement standards in the United States. See Standards Laboratories for an
international listing.
noise (electrical). Unwanted electrical signals that produce undesirable effects in circuits of control systems in which they
occur.2
normalized sensitivity. For resistors, signal sensitivity (dR/dT) is geometry dependent; i.e., dR/dT scales directly with R;
consequently, very often this sensitivity is normalized by dividing by the measured resistance to give a sensitivity, sT, in
percent change per kelvin. sT = (100/R) (dR/dT) %K, where T is the temperature in kelvin and R is the resistance in
ohms.
normally closed (N.C.). A term used for switches and relay contacts. Provides a closed circuit when actuator is in the
free (unenergized) position.
normally open (N.O.). A term used for switches and relay contacts. Provides an open circuit when actuator is in the free
(unenergized) position.
oersted (Oe). The cgs unit for the magnetic field strength (H). 1 oersted = 10¾π ampere/meter ≈ 79.58 ampere/meter.
ohm (Ω). The SI unit of resistance (and of impedance). The ohm is the resistance of a conductor such that a constant
current of one ampere in it produces a voltage of one volt between its ends.2
2
–4
–5
2
–3
pascal (Pa). The SI unit of pressure equal to 1 N/m . Equal to 1.45 × 10 psi, 1.0197 × 10 kgf /cm , 7.5 × 10 torr,
4.191 × 10–3 inches of water, or 1 × 10–5 bar.
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
of the form aixi, where ai is the ith fit coefficient and xi is some function of the dependent variable.
pounds per square inch (psi). A unit of pressure. 1 psi = 6.89473 kPa. Variations include psi absolute (psia) measured
relative to vacuum (zero pressure) where one atmosphere pressure equals 14.696 psia and psi gauge (psig) where
gauge measured relative to atmospheric or some other reference pressure.
A-4
Glossary of Terminology
Lake Shore Model 421 Gaussmeter User’s Manual
ppm. Parts per million, e.g., 4 × 10–6 is four parts per million.
precision. Careful measurement under controlled conditions which can be repeated with similar results. See repeatability.
Also means that small differences can be detected and measured with confidence. See resolution.
prefixes. SI prefixes used throughout this manual are as follows:
Factor
Prefix
Symbol
Factor
Prefix
Symbol
1024
10–1
yotta
Y
deci
d
21
–2
zetta
Z
centi
c
10
10
1018
10–3
exa
E
milli
m
15
–6
peta
P
micro
µ
10
10
12
10
10–9
tera
T
nano
n
9
–12
giga
G
pico
p
10
10
106
10–15
mega
M
femto
f
3
–18
kilo
k
atto
a
10
10
102
10–21
hecto
h
zepto
z
1
–24
deka
da
yocto
y
10
10
probe. A long, thin body containing a sensing element which can be inserted into a system in order to make
measurements. Typically, the measurement is localized to the region near the tip of the probe.
remanence. The remaining magnetic induction in a magnetic material when the material is first saturated and then the
applied field is reduced to zero. The remanence would be the upper limit to values for the remanent induction. Note that
no strict convention exists for the use of remanent induction and remanence and in some contexts the two terms may
be used interchangeably.
remanent induction. The remaining magnetic induction in a magnetic material after an applied field is reduced to zero.
Also see remanence.
repeatability. The closeness of agreement among repeated measurements of the same variable under the same
2
conditions.
2
resolution. The degree to which nearly equal values of a quantity can be discriminated.
display resolution. The resolution of an instrument's physical display. This is not always the same as the
measurement resolution of the instrument. Decimal display resolution specified as "n digits" has 10n possible display
values. A resolution of n and one-half digits has 2 × 10n possible values.
measurement resolution. The ability of an instrument to resolve a measured quantity. For digital instrumentation this
is often defined by the analog to digital converter being used. A n-bit converter can resolve one part in 2n. The
n
smallest signal change that can be measured is the full scale input divided by 2 for any given range. Resolution
should not be confused with accuracy.
root mean square (RMS). The square root of the time average of the square of a quantity; for a periodic quantity the
average is taken over one complete cycle. Also known as effective value.1
RS-232C. Bi-directional computer serial interface standard defined by the Electronic Industries Association (EIA). The
interface is single-ended and non-addressable.
1
scalar. A quantity which has magnitude only and no direction, in contrast to a vector.
semiconducting material. A conducting medium in which the conduction is by electrons, and holes, and whose
temperature coefficient of resistivity is negative over some temperature range below the melting point.2
semiconductor. An electronic conductor, with resistivity in the range between metals and insulators, in which the electric
charge carrier concentration increases with increasing temperature over some temperature range. Note: Certain
2
semiconductors possess two types of carriers, namely, negative electrons and positive holes.
sensitivity. The ratio of the response or change induced in the output to a stimulus or change in the input. Temperature
sensitivity of a resistance temperature detector is expressed as S = dR/dT.
1
setpoint. The value selected to be maintained by an automatic controller.
serial interface. A computer interface where information is transferred one bit at a time rather than one byte (character)
at a time as in a parallel interface. RS-232C is a common serial interface.
SI. Système International d'Unités. See International System of Units.
stability. The ability of an instrument or sensor to maintain a constant output given a constant input.
susceptance. In electrical terms, susceptance is defined as the reciprocal of reactance and the imaginary part of the
complex representation of admittance: [suscept(ibility) + (conduct)ance].
susceptibility (χ). Parameter giving an indication of the response of a material to an applied magnetic field. The
susceptibility is the ratio of the magnetization (M) to the applied field (H). χ = M/H. In both SI units and cgs units the
volume susceptibility is a dimensionless parameter. Multiply the cgs susceptibility by 4π to yield the SI susceptibility.
See also Initial Susceptibility and Differential Susceptibility. As in the case of magnetization, the susceptibility is often
seen expressed as a mass susceptibility or a molar susceptibility depending upon how M is expressed.
Glossary of Terminology
A-5
Lake Shore Model 421 Gaussmeter User’s Manual
temperature scales. See Kelvin Scale, Celsius Scale, and ITS-90. Proper metric usage requires that only kelvin and
degrees Celsius be used. However, since degrees Fahrenheit is in such common use, all three scales are delineated as
follows:
Boiling point of water
Triple point of water
Freezing point of water
373.15 K
273.16 K
273.15 K
Absolute zero
0K
kelvin
100 °C
212 °F
0 °C
32 °F
–273.15 °C
Celsius
–459.67 °F
Fahrenheit
To convert kelvin to Celsius, subtract 273.15.
To convert Celsius to Fahrenheit: multiply °C by 1.8 then add 32, or: °F = (1.8 × °C) + 32.
To convert Fahrenheit to Celsius: subtract 32 from °F then divide by 1.8, or: °C = (°F – 32 ) / 1.8.
temperature coefficient, measurement. The measurement accuracy of an instrument is affected by changes in ambient
temperature. The error is specified as an amount of change (usually in percent) for every one degree change in ambient
temperature.
4
tesla (T). The SI unit for magnetic flux density (B). 1 tesla = 10 gauss
thermal emf. An electromotive force arising from a difference in temperature at two points along a circuit, as in the
Seebeck effect.1
tolerance. The range between allowable maximum and minimum values.
turns (N). One complete loop of wire.
Underwriters Laboratories (UL). An independent laboratory that establishes standards for commercial and industrial
products.
unit magnetic pole. A pole with a strength such that when it is placed 1 cm away from a like pole, the force between the
two is 1 dyne.
vector. A quantity that has both magnitude and direction, and whose components transform from one coordinate system
1
to another in the same manner as the components of a displacement. Also known as a polar vector.
volt (V). The difference of electric potential between two points of a conductor carrying a constant current of one ampere,
2
when the power dissipated between these points is equal to one watt.
volt-ampere (VA). The SI unit of apparent power. The volt-ampere is the apparent power at the points of entry of a singlephase, two-wire system when the product of the RMS value in amperes of the current by the RMS value in volts of the
voltage is equal to one.2
2
watt (W). The SI unit of power. The watt is the power required to do work at the rate of 1 joule per second.
weber (Wb). The unit of magnetic flux in the mks system, equal to the magnetic flux which, linking a circuit of one turn,
produces in it an electromotive force of 1 volt as it is reduced to zero at a uniform rate in 1 second.1
References:
1
Sybil P. Parker, Editor. Dictionary of Scientific and Technical Terms: Third Edition. New York: McGraw Hill, 1969
(IBSN 0-395-20360-0)
2
Christopher J. Booth, Editor. The New IEEE Standard Dictionary of Electrical and Electronic Terms: IEEE Std 100-1992, Fifth
Edition. New York: Institute of Electrical and Electronics Engineers, 1993 (IBSN 1-55937-240-0). Definitions printed with permission
of the IEEE.
Nelson, Robert A. Guide For Metric Practice, Page BG7 - 8, Physics Today, Eleventh Annual Buyer’s Guide, August 1994
(ISSN 0031-9228 coden PHTOAD)
3
A-6
Glossary of Terminology
Lake Shore Model 421 Gaussmeter User’s Manual
APPENDIX B
UNITS FOR MAGNETIC PROPERTIES
Table B-1. Conversion from CGS to SI Units
Quantity
Symbol
Gaussian
and CGS emua
Conversion
Factor, Cb
SI and
Rationalized mksc
Magnetic flux density,
Magnetic induction
B
gauss (G)d
10-4
tesla (T), Wb/m2
Magnetic Flux
φ
maxwell (Mx), G•cm2
10-8
weber (Wb),
volt second (V•s)
Magnetic potential difference,
magnetomotive force
U, F
gilbert (Gb)
10/4π
ampere (A)
Magnetic field strength,
magnetizing force
H
oersted (Oe),e Gb/cm
103/4π
A/mf
(Volume) magnetization
(Volume) magnetization
Magnetic polarization,
intensity of magnetization
M
4πM
emu/cm3h
G
103
3
10 /4π
A/m
A/m
J, I
emu/cm3
4π × 10-4
T, Wb/m2i
(Mass) magnetization
σ, M
emu/g
1
4π × 10-7
Magnetic moment
m
emu, erg/G
10-3
Magnetic dipole moment
j
(Volume) susceptibility
χ, κ
emu, erg/G
dimensionless
emu/cm3
4π × 10-10
—
(4π)2 × 10-7
A•m2/kg
Wb•m/kg
A•m2, joule per
tesla (J/T)
Wb•mi
Henry per meter
(H/m), Wb/(A•m)
(Mass) susceptibility
χρ, κρ
cm3/g, emu/g
4π × 10-3
-10
(4π)2 × 10
m3/kg
2
H•m /kg
(Molar) susceptibility
χmol, κmol
cm3/mol, emu/mol
Permeability
j
Relative permeability
(Volume) energy density,
k
energy product
µ
µr
dimensionless
not defined
4π × 10-6
(4π)2 × 10-13
4π × 10-7
—
m3/mol
H•m2/mol
H/m, Wb/(A•m)
dimensionless
W
erg/cm3
10-1
J/m3
Demagnetization factor
D, N
dimensionless
1/4π
dimensionless
g
NOTES:
a.
Gaussian units and cgs emu are the same for magnetic properties. The defining relation is B = H + 4πM.
b.
Multiply a number in Gaussian units by C to convert it to SI (e.g. 1 G × 10-4T/G = 10-4T).
c.
SI (Système International d'Unités) has been adopted by the National Bureau of Standards. Where two conversion factors are given, the
upper one is recognized under, or consistent with, SI and is based on the definition B = µ0(H + M), where to µ0 = 4π × 10-7H/m. The lower one
is not recognized under SI and is based on the definition B = µ0H + J, where the symbol I is often used in place of J.
d.
1 gauss = 105 gamma (γ).
e.
Both oersted and gauss are expressed as cm-½ •g½•s-1 in terms of base units.
f.
A/m was often expressed as "ampere-turn per meter" when used for magnetic field strength.
g.
Magnetic moment per unit volume.
h.
The designation "emu" is not a unit.
i.
Recognized under SI, even though based on the definition B = µ0H + J. See footnote c.
j.
µr = µ/µ0 = 1 + χ, all in SI. µr is equal to Gaussian µ.
k.
B • H and µ0M • H have SI units J/m3, M • H and B • H/4π have Gaussian units erg/cm3.
R.B. Goldfarb and F.R. Fickett, U.S. Department of Commerce, National Bureau of Standards, Bolder, Colorado 80303, March 1985, NBS Special
Publication 696. For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402.
Units for Magnetic Properties
B-1
Lake Shore Model 421 Gaussmeter User’s Manual
Table B-2. Recommended SI Values for Physical Constants
Quantity
Symbol
Value (SI units)
Permeability of Vacuum
µ0
4π × 10-7 H m-1
Speed of Light in Vacuum
c
2.9979 × 108 m s-1
Permitivity of Vacuum
ε0 = (µ0c2)-1
8.8542 × 10-12 F m-1
Fine Structure Constant, µ0ce2/2h
α
α-1
0.0073
137.0360
Elementary Charge
e
1.6022 × 10-19 C
Plank's Constant
h
h = h/2π
6.6262 × 10-34 J Hz-1
1.0546 × 10-34 J s
Avogadro's Constant
NA
6.0220 × 1023 mol-1
Atomic Mass Unit
1 u = 10-3 kg mol-1/NA
1.6605 × 10-27 kg
Electron Rest Mass
me
Proton Rest Mass
mp
Neutron Rest Mass
mn
Magnetic Flux Quantum
φ = h/2e
h/e
0.9109 × 10-30 kg
5.4858 × 10-4 u
1.6726 × 10-27 kg
1.0073 u
1.6749 × 10-27 kg
1.0087 u
2.0679 × 10-15 Wb
4.1357 × 10-15 J Hz-1 C-1
Josephson Frequency-Voltage Ratio
2e/h
483.5939 THz V-1
Quantum of Circulation
h/2me
h/me
3.6369 × 10-4 J Hz-1 kg-1
7.2739 × 10-4 J Hz-1 C-1
Rydberg Constant
R∞
1.0974 × 107 m-1
Proton Moment in Nuclear Magnetons
µp/µN
2.7928
Bohr Magneton
µB = eh/2me
9.2741 × 10-24 J T-1
Proton Gyromagnetic Ratio
γp
2.6752 × 108 s-1 T-1
Diamagnetic Shielding Factor, Spherical H2O Sample
1 + σ(H2O)
1.0000
Molar Mass Constant
R
8.3144 J mol-1 K-1
Molar Volume, Ideal Gas (T0 = 273.15K, p0 = 1 atm)
Vm = RT0/p0
0,0224 m3 mol-1
Boltzman Constant
k = R/NA
1.3807 × 10-23 J K-1
Stefan-Boltzman Constant
σ = (π2/60) k4/h3 c2
5.6703 × 10-8 W m-2 K-4
First Radiation Constant
c1= 2πhc2
3.7418 × 10-16 W m-2
Second Radiation Constant
c2 = hc/k
0.0144 mK
Gravitation Constant
G
6.6720 × 10-11 N m2 kg-2
Data (abbreviated to 4 decimal places) from CODATA Bulletin No. 11, ICSU CODATA Central Office,
19 Westendstrasse, 6 Frankfurt/Main, Germany. Copies of this bulletin are available from this office.
B-2
Units for Magnetic Properties
Lake Shore Model 421 Gaussmeter User’s Manual
APPENDIX C
HALL GENERATORS
C1.0
GENERAL
This chapter provides theory of operation, specifications, mechanical drawings, and definition of
terminology. Hall Generator theory of operation is detailed in Paragraph C2.0. Generic Hall generator
hookup is detailed in Paragraph C3.0. Hookup to a Model 421 Gaussmeter is discussed in
Paragraph C4.0. Specifications of the various available Hall generators are detailed in
Paragraph C5.0. Finally, the HALLCAL.EXE program is detailed in Paragraph C6.0. Additional
installation and calibration information is available in Lake Shore Document Number F075-00-00 –
Hall Generator Application Guide.
C2.0
THEORY OF OPERATION
The Hall effect was discovered by E. H. Hall in 1879. For nearly 70 years it remained a laboratory
curiosity. Finally, development of semiconductors brought Hall generators into the realm of the
practical.
A Hall generator is a solid state sensor which provides an output voltage proportional to magnetic flux
density. As implied by its name, this device relies on the Hall effect. The Hall effect is the
development of a voltage across a sheet of conductor when current is flowing and the conductor is
placed in a magnetic field. See Figure C-1.
Electrons (the majority carrier most often used in practice) “drift” in the conductor when under the
influence of an external driving electric field. When exposed to a magnetic field, these moving
charged particles experience a force perpendicular to both the velocity and magnetic field vectors.
This force causes the charging of the edges of the conductor, one side positive with respect to the
other. This edge charging sets up an electric field which exerts a force on the moving electrons equal
and opposite to that caused by the magnetic-field-related Lorentz force. The voltage potential across
the width of the conductor is called the Hall voltage. This Hall voltage can be utilized in practice by
attaching two electrical contacts to the sides of the conductor.
The Hall voltage can be given by the expression:
VH = γB B sin θ
where: VH = Hall voltage (mV)
γB = Magnetic sensitivity (mV/kG) (at a fixed current)
B = Magnetic field flux density (kilogauss)
θ = Angle between magnetic flux vector and the plane of Hall generator.
As can be seen from the formula, above, the Hall voltage varies with the angle of the sensed
magnetic field, reaching a maximum when the field is perpendicular to the plane of the Hall generator.
C2.1
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. Due to the shorting effect of the current supply
contacts, most of the sensitivity to magnetic fields is contained in an area approximated by a circle,
centered in the Hall plate, whose diameter is equal to the plate width. Thus, when the active area is
given, the circle as described above is the common estimation.
Hall Generator
C-1
Lake Shore Model 421 Gaussmeter User’s Manual
v
Ic (+)
(Red)
Conventional
Current
B
F
F = –e (v × B)
(force on electron)
VH (+)
(Blue)
+
–
+
–
+
–
+
–
High Mobility III-V
Semiconductor
a) Indium arsenide
b) Gallium arsenide
v
B
VH (–)
(Clear or Yellow)
e
Ic (–)
(Green or Black)
C-421-C-1.eps
Figure C-1. Hall Generator Theory
C2.2
ORIENTATION
Hall generators come in two main configurations, axial and transverse. Transverse devices are
generally thin and rectangular in shape. They are applied successfully in magnetic circuit gaps,
surface measurements and general open field measurements. Axial sensors are mostly cylindrical in
shape. Their applications include ring magnet center bore measurements, solenoids, surface field
detection and general field sensing.
+B
Transverse
+B
Axial
C-421-C-2.eps
Figure C-2. Axial and Transverse Configurations
C-2
Hall Generator
Lake Shore Model 421 Gaussmeter User’s Manual
C2.3
HANDLING
CAUTION: Care must be exercised when handling the Hall generator. The Hall generator is
very fragile. Stressing the Hall generator can alter its output. Any excess force
can easily break the Hall generator. Broken Hall generators are not repairable.
Hall Generators are very fragile and require delicate handling. The ceramic substrate used to produce
the Hall Generator is very brittle. Use the leads to move the Hall generator. Do not handle the
substrate. The strength of the lead-to-substrate bond is about 7 ounces, so avoid tension on the leads
and especially avoid bending them close to the substrate. The Hall Generator is also susceptible to
bending and thermal stresses.
C2.4
POLARITY
If the control current enters the red lead (with +IC connected to the positive terminal of the current
supply), and the magnetic field direction is as shown in Figure C-2, a positive Hall voltage will be
generated at the blue lead (+VH). Reversing either the current or the magnetic field will reverse the
output voltage.
C2.5
LEAD CONFIGURATIONS
All Hall generators (except Models HGCA-3020 and HGCT-3020) have 34 AWG solid copper with
poly-nylon insulation and have the same lead configuration as follows:
Red = +IC
Green = –IC
Blue = +VH
Clear = –VH
} Input (Control Current)
} Output (Hall Voltage)
The Model HGCA-3020 and HGCT-3020 Hall generators have 34 AWG stranded copper with Teflon®
insulation and have the following lead configuration:
Red = +IC
Black = –IC
Blue = +VH
Yellow = –VH
C3.0
} Input (Control Current)
} Output (Hall Voltage)
HALL GENERATOR GENERIC HOOKUP
The Hall voltage leads may also be connected directly to a readout instrument, such as a high
impedance voltmeter, or can be attached to electronic circuitry for amplification or conditioning.
Device signal levels will be in the range of microvolts to hundreds of millivolts. In this case, a separate
precision current source (Lake Shore Model 120CS or equivalent) is necessary. See Figure C-3.
CAUTION: The four Hall generator leads connect to four points on a sheet of semiconductor
material having different potentials. No two leads can be connected together
without adversely affecting operation. Therefore, the current source and the output
indicator cannot have a common connection, but must be isolated from each other.
One, the other, but not both, may be grounded.
CAUTION: Do not exceed the maximum continuous control current given in the specifications.
The Hall generator input is not isolated from its output. In fact, impedance levels on the order of the
input resistance are all that generally exist between the two ports. To prevent erroneous current
paths, which can cause large error voltages, the current supply must be isolated from the output
display or the down stream electronics.
Hall Generator
C-3
Lake Shore Model 421 Gaussmeter User’s Manual
+IC
Hall Generator
IC
+VH
Model 120CS
Current Source
+
–VH
Digital Voltmeter
–
VH
RL
Load resistor required
for optimum linearity
(if specified)
–IC
C-421-C-3.eps
Figure C-3. Typical Hall Generator Hookup
C4.0
USING A HALL GENERATOR WITH THE MODEL 421
To hookup a Hall generator you must use a Lake Shore Model MCBL-6 Cable Assembly. The cable is
200 cm (79 inches) long with a DA-15 connector on one end and four leads on the other. The Hall
generator is a 4-lead device. The 4 leads are labeled +Ic (Red), –Ic (Black or Green), +VH (Blue), and
–VH (Yellow), corresponding to the 4 leads on all the Hall generators.
The Model 421 has an input impedance of 420 Ω. Therefore, the actual sensitivity at the gaussmeter
input will be less than the value given with the Hall generator due to drop in the leads and cable. This
fact is important because a sensitivity value is supposed to be loaded into the cable PROM to set
calibration. We recommend that the customer always check accuracy against a reference field rather
than use the sensitivity value sent with the bare Hall generator. Because Lake Shore has no control
of the conditions beyond the cable, the customer must accept responsibility for accuracy and
compatibility.
Finally, Manganin wire is not usually acceptable for cryogenic installations. The resistance of
Manganin wire is often too high. In cryogenic applications, Hall generators are normally connected
using twisted pairs of copper wire such as 34 gauge, Teflon insulated. There are two reasons for this:
1. The gaussmeter current source is normally limited in compliance voltage. The Model 421 should
not drive a load (Hall generator, Wires in cryostat, and probe cable) greater than 50 Ω. In fact, for
best performance, the load should be less than 30 Ω.
2. Because the Model 421 input impedance is 420 Ω, there is a voltage drop due to lead resistance
in series with the gaussmeter input. The Lake Shore Hall generator sensitivity given on the data
sheet is basically with no lead resistance. See Figure C-4.
The gaussmeter needs input sensitivity
between 0.5 to 1.5 mV/kG (HST) or
5.0 and 15 mV/kG (HSE) at its input
Gaussmeter
Input
Rcable
Rcust
420 Ω
VH
Rcable
Sensitivity at Gaussmeter input is
reduced by the lead/input voltage divider
Hall Generator
Open Circuit
Sensitivity
Rcable = Lake Shore Model
MCBL-6 Cable Assembly
Rcust
Rcust = Customer
Supplied Leads
C-421-C-4.eps
Figure C-4. Hall Generator Input Impedance
C-4
Hall Generator
Lake Shore Model 421 Gaussmeter User’s Manual
C5.0
SPECIFICATIONS
This section covers three types of Hall generators available from Lake Shore: HGCA & HGCT Series
Cryogenic Hall generators (Figures C-5 and C-6) with specifications (Table C-1), HGA Series Axial
Hall generators (Figures C-5 and C-7) with specifications (Table C-2), and HGT Series Transverse
Hall generators (Figures C-8 thru C-10) with specifications (Table C-3).
10 in. (min.)
0.25 in.
diameter
0.20 in.
+B
0.20 in. diameter
0.105 in.
C-421-C-5.eps
Figure C-5. Axial Hall Generator HGA-3010, HGA-3030, and HGCA-3020 Dimensions
10 in. (min.)
(Lead Length)
0.63 in.
0.180 in.
0.240 in.
(max.)
+B
Center of
Active Area
Protective
Ceramic Case
0.043 in. (max.)
C-421-C-6.eps
Figure C-6. Transverse Hall Generator HGT-3010, HGT-3030, and HGCT-3020 Dimensions
Table C-1. Cryogenic Hall Generator Specifications
Cryogenic
Description
HGCA-3020
Cryogenic axial; phenolic package
HGCT-3020
Cryogenic transverse; ceramic package
Active area (approximate)
0.030 inch diameter circle
0.040 inch diameter circle
Input resistance (approximate)
1 ohm
1 ohm
Output resistance (approximate)
1 ohm
1 ohm
Nominal control current (ICN)
100 mA
100 mA
Maximum continuous current
(non-heat sinked)
300 mA
300 mA
Magnetic sensitivity (IC = nominal control
current)
0.55 to 1.05 mV/kG
0.55 to 1.05 mV/kG
Maximum linearity error
(sensitivity vs field)
±1.0% RDG (-30 to +30 kG)
±2.0% RDG (-150 to +150 kG)
±1.0% RDG (-30 to +30 kG)
±2.0% RDG (-150 to +150 kG)
Zero field offset voltage (IC = nominal
control current)
±200 µV (max.)
±200 µV (max.)
Operating temperature range
4.2 K to 375 K
4.2 K to 375 K
Mean temperature coefficient of magnetic
sensitivity
±0.01%/K (approx.)
±0.01%/K (approx.)
Mean temperature coefficient of offset (IC
= nominal control current)
±0.4 µV/K (max.)
±0.4 µV/K (max.)
Mean temperature coefficient of resistance
±0.6%/K (max.)
±0.6%/K (max.)
Leads
34 AWG copper w/Teflon insulation
34 AWG copper w/Teflon insulation
Hall Generator
C-5
Lake Shore Model 421 Gaussmeter User’s Manual
0.50 in.
10 in. (min.)
0.125 in.
Center of
Active Area
0.130 in. (max.)
+B
0.020 in.
(max.) over
Hall plate
0.028 in. (max.)
over leads
C-421-C-7.eps
Figure C-7. Transverse Hall Generator HGT-1010 Dimensions
Table C-2. Axial Hall Generator Specifications
Axial
HGA-3010
HGA-3030
Description
Instrumentation quality axial; low
temperature coefficient; phenolic
package
Instrumentation quality axial; phenolic
package
Active area (approximate)
0.030 inch diameter circle
0.030 inch diameter circle
Input resistance (approximate)
1 ohm
2 ohms
Output resistance (approximate)
1 ohm
2 ohms
Nominal control current (ICN)
100 mA
100 mA
Maximum continuous current (nonheat sinked)
300 mA
300 mA
Magnetic sensitivity (IC = nominal
control current)
0.55 to 1.05 mV/kG
6.0 to 10.0 mV/kG
Maximum linearity error (sensitivity
versus field)
±1% RDG (–30 to +30 kG)
±1.5% RDG (–100 to +100 kG)
±0.30% RDG (–10 to +10 kG)
±1.25% RDG (–30 to +30 kG)
Zero field offset voltage (IC = nominal
control current)
±50 µV (max.)
±75 µV (max.)
Operating temperature range
–40 to +100 °C
–40 to +100 °C
Mean temperature coefficient of
magnetic sensitivity
±0.005%/°C (max.)
–0.04%/°C (max.)
Mean temperature coefficient of offset
(IC = nominal control current)
±0.4 µV/°C (max.)
±0.3 µV/°C (max.)
Mean temperature coefficient of
resistance
±0.15%/°C (approx.)
+0.18%/°C (approx.)
Leads
34 AWG copper with poly-nylon
insulation
34 AWG copper with poly-nylon
insulation
C-6
Hall Generator
Lake Shore Model 421 Gaussmeter User’s Manual
Table C-3. Transverse Hall Generator Specifications
Transverse
Description
HGT-1010
HGT-3010
HGT-3030
General purpose
transverse; 0.020 inch thick
Instrumentation quality
transverse; low temperature
coefficient; ceramic
package
Instrumentation quality
transverse ceramic package
Active area (approximate)
0.040 inch diameter circle
0.040 inch diameter circle
0.040 inch diameter circle
Input resistance (approx.)
2 ohms
1 ohm
2 ohms
Output resistance (approx.)
2 ohms
1 ohm
2 ohms
Nominal control current
(ICN)
100 mA
100 mA
100 mA
Maximum continuous
current (non-heat sinked)
300 mA
300 mA
300 mA
Magnetic sensitivity (IC =
nominal control current)
7.5 to 12.5 mV/kG
0.55 to 1.05 mV/kG
6.0 to 10.0 mV/kG
Maximum linearity error
(sensitivity versus field)
±1.0% RDG
(-10 to 10 kG)
±1% RDG
(-30 to 30 kG)
±1.5% RDG
(-100 to 100 kG)
±0.30% RDG
(-10 to 10 kG)
±1.25% RDG
(-30 to 30 kG)
Zero field offset voltage (IC
= nominal control current)
±100 µV max.
±50 µV max.
±75 µV max.
Operating temperature
range
–40 to +100 °C
–40 to +100 °C
–40 to +100 °C
Mean temperature
coefficient of magnetic
sensitivity
–0.08%/°C max.
±0.005%/°C max.
–0.04%/°C max.
Mean temperature
coefficient of offset (IC =
nominal control current)
±1 µV/°C max.)
±0.4 µV/°C max.
±0.3 µV/°C
Mean temperature
coefficient of resistance
±0.18%/°C approx.
±0.15%/°C approx.
+0.18%/°C approx.
Leads
34 AWG copper with polynylon insulation.
34 AWG copper with polynylon insulation
34 AWG copper with polynylon insulation
Hall Generator
C-7
Lake Shore Model 421 Gaussmeter User’s Manual
C6.0
HALLCAL.EXE PROGRAM
The HALLCAL.EXE program was developed by Lake Shore Cryotronics, Inc. to allow the interfacing of
customer attached Hall generators to the Model 421 Gaussmeter. (Please refer to the Software License
Agreement behind the title page of this manual.) This program is provided with the purchase of a Model
MCBL-6 or -20 Cable Assembly. Because of the many intricacies involved with proper calibration, the
Customer must accept responsibility for the measurement accuracy.
Requirements:
•
Lake Shore Model 421 Gaussmeter (connected via RS-232 to the computer in the COM1 port).
•
Lake Shore Model MCBL-6 or -20 Cable Assembly.
•
IBM or compatible CPU.
•
Hall generator meeting the sensitivity ranges given below.
•
Calibration or sensitivity constant and serial number of the Hall generator.
1. Set the Lake Shore Model 421 Gaussmeter to 300 Baud. Refer Paragraph 3.11 of this User’s Manual on
how to set the Gaussmeter to communicate at 300 Baud.
2. Insert the 3.5-inch disk and type in the default drive (A: or B:).
3. Type in HALLCAL. This will execute the HALLCAL.EXE program.
4. The program will prompt for the Probe serial number. Any combination of 6 letters or number can be
entered. Press Enter when this is accomplished.
5. The program will prompt for the probe type (0 or 1).
Enter “0” for Hall generators with sensitivities between 5.5 and 10.5 mV/kG (@ 100 mA current).
Enter “1” for Hall generators with sensitivities between 0.55 and 1.05 mV/kG (@ 100 mA current).
6. The program will prompt for the “Calibration Constant.” Enter the magnetic sensitivity in mV/kG at a
control current of 100 mA. Remember to account for the 420 Ω input impedance of the Gaussmeter when
calculating the proper load resistor to install.
7. The program will display all the values entered along with designated F keys:
F1
Probe Serial Number
ABC123
F2
Probe Type
0
F3
Calibration Constant
X.XXX
F10
Program Probe
Esc
Exit Program
8. At this time, if any of the parameters need to be changed, just press the appropriate F key and type in the
new value. When everything appears correct, press F10 to program the probe.
9. It takes about 20 seconds to program the probe. After the probe is programmed, press the Esc key to exit
the program.
SOFTWARE LICENSE AGREEMENT
This software is protected by United States copyright law and international treaty provisions. Lake Shore provides this software package
and grants you (the user of the software) a non-exclusive and non-transferable right to use this software. Unless as provided in this
Agreement, any attempt to sublicense, lease, rent, assign, or transfer this license or this software is void. To maintain software warranty,
the source code must not be modified. Any changes made to the HALLCAL.EXE source code is at the user’s risk. Lake Shore assumes
no responsibility for damage or errors incurred as result of any changes made to the source code.
This agreement allows you to use the HALLCAL.EXE Software on any one computer system. One archival floppy disk is permitted. Any
unauthorized duplication or use of the software in whole or in part, in print, or in any other storage and retrieval system is forbidden.
Lake Shore works to ensure the HALLCAL.EXE Software is as free of errors as possible, and that the results you obtain from the system
are accurate and reliable. However, understand that with any computer software the possibility of software errors exist. In any important
research, as when using any laboratory equipment, results should be carefully examined and rechecked before final conclusions are
drawn. Neither Lake Shore nor anyone else involved in the creation or production of this software can pay for loss of time, inconvenience,
lost of use of the product, or property damage caused by this product or its failure to work, or any other incidental or consequential
damages. Use of our product implies that you understand the Lake Shore license agreement and statement of limited warranty.
C-8
Hall Generator
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