Applied Physics Systems 1540 User manual

MODEL 1540
FLUXGATE MAGNETOMETER
USER MANUAL
CONTACT US
HEADQUARTERS
425 Clyde Avenue Mountain View, CA 94043
OFFICE
650.965.0500
EMAIL
[email protected]m
APPLIEDPHYSICS.COM

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COPYRIGHT
Copyright 2014 - 2022 Applied Physics Systems Incorporated.
All Rights Reserved.
The contents of this manual may not be reprinted in part or whole without
permission.
The contents of this manual are subject to change without notice.
TRADEMARKS
All other brands or products mentioned are trademarks or registered trademarks
of their respective holders and should be treated as such.
CONTACT INFORMATION
Applied Physics Systems
Corporate Headquarters
425 Clyde Avenue
Mountain View, California 94043 USA
Phone: [phone]
Email: [email protected]
Web: www.appliedphysics.com
Technical Support Hours:
Monday - Friday
9:00 AM - 5:00 PM
Pacific Standard Time
DOCUMENT NUMBER
260-0183-03-0722

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REVISION HISTORY
Revision
Description
Date
1
Initial draft of this manual.
June 2014
2
Renamed “binary constant” to “byte constant”.
April 2017
Renamed “floating constant” to “float constant”.
Updated system specifications.
Table 1. System Specifications
Updated the Model 1540 mechanical drawing.
Figure 1. Model 1540 Cylindrical Magnetometer
Updated the Model 1540S mechanical drawing.
Figure 2. Model 1540S Rectangular
Magnetometer Mechanical Drawing
Updated the Model 1540 and 1540S electrical
interface.
Table 3. Model 1540S Electrical Interface,
Figure 2. Model 1540S Rectangular
Magnetometer Mechanical Drawing and Figure
3. Model 1540 with Leads
Updated the Model 1540 sensor commands.
Table 4. Model 1540 Commands
Updated the byte constants.
Table 5. Commonly Used Byte Constants and
Table 12. Model Byte Constants
Updated the float constants.
Table 13. Model 1540 Float Constants
3
New Format
July 2022

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TABLE OF CONTENTS
MODEL 1540 ........................................................................................................................................................................................ 1
COPYRIGHT ........................................................................................................................................................................................ 2
TRADEMARKS ....................................................................................................................................................................................2
CONTACT INFORMATION ...........................................................................................................................................................2
DOCUMENT NUMBER .................................................................................................................................................................... 2
REVISION HISTORY..........................................................................................................................................................................3
FIGURES................................................................................................................................................................................................5
TABLES...................................................................................................................................................................................................5
1–INTRODUCTION.........................................................................................................................................................................6
2-SYSTEM SPECIFICATIONS.................................................................................................................................................... 7
3-MECHANICAL FEATURES ......................................................................................................................................................9
4-ELECTRICAL INTERFACE........................................................................................................................................................11
4.1 -SETTING UP THE ELECTRICAL CONNECTIONS...................................................................................................... 14
5-COMPUTER INTERFACE....................................................................................................................................................... 16
5.1 –MODEL 1540 SENSOR COMMANDS .......................................................................................................................... 16
5.2 -1540 BYTE CONSTANTS.................................................................................................................................................. 19
5.3 –MODEL 1540 FLOAT CONSTANTS ............................................................................................................................ 20
5.4 -ASCII AND BINARY MODE ............................................................................................................................................. 20
5.5 -CONFIGURING THE MODEL 1540 SYSTEM............................................................................................................ 22
5.5.1 -CHANGING THE ASCII DATA OUTPUT MODE................................................................................................... 23
5.5.2 -CHANGING THE BAUD RATE.................................................................................................................................... 23
5.5.3 -CONFIGURING THE MODEL 1540 SENSOR FOR AUTOSEND.................................................................... 24
5.5.4 -AVERAGING AND FILTERING MODEL 1540 OUTPUT DATA.......................................................................25
5.6 -USING THE ASCII COMMUNICATION MODE....................................................................................................... 26
5.6.1 -ASCII AUTOSEND MODE ..............................................................................................................................................27
5.7 -STANDARD BINARY COMMUNICATION MODES................................................................................................27
5.7.1 -COMMAND <128>: SEND SENSOR (VECTOR) DATA IN STANDARD BINARY FORMAT................ 28
5.7.2 -COMMAND <129>: SEND ALL DATA AS VECTORS IN AN IEEE FLOAT FORMAT............................... 29
5.7.3 -AUTOSEND BINARY COMMUNICATION MODE..............................................................................................30
6-OPERATING THE MODEL 1540......................................................................................................................................... 30
6.1 -SENSOR INTERFACE SOFTWARE...................................................................................................................................31
A-BYTE CONSTANTS AND FLOAT CONSTANTS......................................................................................................... 38
A.1 –MODEL 1540 BYTE CONSTANTS.................................................................................................................................38
A.2 –MODEL 1540 FLOAT CONSTANTS ............................................................................................................................ 42

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FIGURES
Figure 1. Model 1540 Cylindrical Magnetometer..................................................................................9
Figure 2. Model 1540S Rectangular Magnetometer Mechanical Drawing.......................10
Figure 3. Model 1540 with Leads......................................................................................................................11
Figure 4. Averaging Example......................................................................................................................... 26
Figure 5. Model 1540 Noise Level Data.......................................................................................................31
Figure 6. Sensor Interfacce Main Display.............................................................................................. 33
Figure 7. Sensor Configure Window.......................................................................................................... 34
Figure 8. Monitor Sensor Window ............................................................................................................... 36
Figure 9. Monitor Sensor Window - ASCII Mode................................................................................ 36
Figure 10. Monitor Sensor Window - Hex Mode...................................................................................37
TABLES
Table 1. System Specifications......................................................................................................................... 7
Table 2. Model 1540 Electrical Interface...................................................................................................12
Table 3. Model 1540S Electrical Interface ................................................................................................13
Table 4. Model 1540 Commands ..................................................................................................................17
Table 5. Commonly Used Byte Constants..............................................................................................19
Table 6. Changing the ASCII Data Output Mode..............................................................................23
Table 7. Baud Rate Settings............................................................................................................................ 24
Table 8. Autosend Modes................................................................................................................................. 25
Table 9. Averaging Values............................................................................................................................... 25
Table 10. Command <80 Hex, 128> Data Format Key.................................................................... 28
Table 11. Command <129> Data Format Key........................................................................................ 29
Table 12. Model Byte Constants ................................................................................................................... 38
Table 13. Model 1540 Float Constants ...................................................................................................... 42

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1 – INTRODUCTION
The Applied Physics Systems Model 1540 is a high speed 3-axis fluxgate
magnetometer employing 22-bit analog-to-digital converters. Magnetic field
data transmitted by the Model 1540 is expressed in Gauss (G).
The Model 1540 system employs three ring core fluxgate sensors together with
analog processing electronics to produce analog output voltages proportional to
the measured magnetic field along three orthogonal axes. The analog output
voltages are converted to digital form using three 24-bit A/D converters. Using 22-
bit converters enables the 1540 system to measure magnetic field magnitudes
from ±0.65 G down to the system noise level (5 microG peak to peak) using a
single range.
The Model 1540 system microprocessor (MSP430) performs the following digital
control functions:
• control and acquisition of data from the 22-bit A/D converter
• correction of fluxgate sensor scale, offset, and alignment factors
• implementation of serial communications between the system and an
external computer
The Model 1540 is calibrated by placing it in a precision 3-axis Helmholtz coil,
which enables the application of accurately known magnetic fields to the system.
Then the Helmholtz coil is fitted with a holding fixture with alignment holes and
reference V grooves that match the 1540 alignment pins and cylindrical body. The
holding fixture enables the Model 1540 to be accurately aligned with the Helmholtz
axes, so that accurate scale and alignment and offset factors can be determined.
After determining the calibration factors, they are downloaded into the 1540 so
the system microprocessor can make calibration corrections on measured
magnetic field data before transmission.
The Model 1540 system communicates over a bidirectional serial interface using
TTL logic levels and RS-232 levels. Three communication protocols are available:
TTL or RS-232 or RS-422. Select one or more of these communications protocols
when ordering a 1540 system. In addition to the ASCII data transmission mode, the
Model 1540 system has a binary transmission mode and an IEEE 32-bit
transmission mode. These modes are faster than the ASCII mode because

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considerably fewer characters need to be transmitted. The default baud rate is
9600 with one stop bit, no parity and 8 data bits.
An autosend data mode is included in the 1540 software. When this mode is
active, data is repeatedly sent out the serial port automatically after power is
applied to the system.
2 - SYSTEM SPECIFICATIONS
Table 1. System Specifications
Specifications are subject to change without notice.
ELECTRICAL
Input Voltage Range
+4.95 to +12 VDC
Current
55 mA
Digital Output Protocols
RS232 and TTL (RS422 optional)
Digital Output Formats
ASCII and Binary
Baud Rate (User Selectable)
300, 1200, 4800, 9600 (default), 38400
A to D Communications
22-bit Sigma Delta
Data Rate in Autosend Mode
ASCII mode: 10 transmissions/sec
Binary mode: 20 transmissions/sec
ENVIRONMENTAL
Operating Temperature
Range
-25°C to +70°C
Shock
1000 G 1 ms half sine wave
Vibration
10 G RMS random 50 Hz to 500 Hz
PERFORMANCE
Dynamic Range
±6.5x105 nTesla (±0.65 Gauss)
Resolution
10 nTesla (1.0x10-7 Gauss)
Accuracy @ full-scale
±0.5% full-scale
Linearity @ full-scale
±0.05% full-scale
Initial Bias at 25°C
<0.005 mG
Temperature Sensitivity
Scale Factor
±0.05% full-scale/°C
Offset versus Temperature
<0.01 mG/°C
Axis Alignment
Better than ±0.2°

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Alignment of sensor
package with sensor
reference surfaces
Better than ±0.2°
Noise Level
±0.5 nT (±5 μGauss) peak-to-peak
Frequency Response
DC to 400 Hz (-3 db)
Analog Bandwidth
100 Hz
Analog Scale Factor
3 V/G
PHYSICAL
Cylinder size including
connection plate
4.81” (122.17 mm) L x 1” (25.4 mm) dia.
Rectangle size (1540S)
4.75” (120.65 mm) L x 1.15” (29.2 mm) x .95” (24.1
mm)
Weight
85 g
Input/Output Connections
Flying leads (Teflon insulated) #28 gauge >6”
(152.4 mm) length or 9-pin nonmagnetic MDM
connector

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3 - MECHANICAL FEATURES
The cylindrical 1540 has an alignment slot on the top surface. This slot aligns with
the Z+ axis direction. The 1540 coordinate directions are shown in Figure 1. A
magnetic field direction aligned with the axis direction arrows will produce a
positive output voltage.
Mechanical Drawing
Figure 1. Model 1540 Cylindrical Magnetometer

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The Model 1540 is also available in an alternative rectangular package, the Model
1540S, shown in Figure 2. Model 1540S Rectangular Magnetometer Mechanical
DrawingFigure 2. Model 1540S Rectangular Magnetometer Mechanical Drawing
Figure 2. Model 1540S Rectangular Magnetometer Mechanical Drawing
Both the Model 1540 and the Model 1540S have a 9-pin MDM connector for
powering and computer interface.