Group3 DTM-133 User manual

01 April 2010
Group3 Technology Limited
2 Charann Place, Avondale, Auckland 1026
P.O. Box 71-111, Rosebank, Auckland 1348, New Zealand.
Phone: [phone] Fax: [phone]
email: [email protected]
web: www.group3technology.com
DTM-133
DIGITAL TESLAMETER
with IEEE-488 GPIB Communication
V1.0
USER’S MANUAL

Thank you for purchasing and using a Group3 digital teslameter. We hope you will join the many hundreds of users
worldwide who are enthusiastic about our products.
Group3 has been designing and building magnetic field measuring equipment since 1983. We are constantly
upgrading our products and support documentation. We welcome input from our customers, so if there are aspects
of the instrument which you particularly like, or which you would like to see improved, please contact your Group3
supplier (seeback page for acomplete list) or Group3 directly with your suggestions to
[e-mail] .
The Group3 website, http://www.group3technoIogy.com contains details of all our products. This site is
regularly updated, so check it from time to time to learn about recent developments.

CONTENTS
1. General Description
1-1
2. Specification of Systems
2-1
3. Setting Up
3-1
3.1 Introduction
3-1
3.2 Installing the Panel Mount Option
3-1
3.3 Connecting the Hall Probe
3-2
3.4 Connecting the Power Source
3-3
3.5 Internal DIP Switches
3-5
3.6 Analog Output
3-5
3.7 Grounding
3-5
3.8 Installation Techniques for Electrically Noisy Environments
3-6
4. Operating Instructions
4-1
4.1 Zeroing
4-1
4.2 Installing the Probe
4-2
4.3 Reading the Field Value
4-3
4.4 Display Modes, Using Front Panel Keys
4-4
4.5 Digital Filtering
4-7
5. IEEE-4988 Interfacing Option
5-1
5.1 IEEE-488 Bus Connection
5-1
5.2 IEEE-488 Board Switch Settings
5-3
5.3 Using the IEEE-488 GPIB Interface
5-4
5.4 Triggered Operation
5-19
LIST OF FIGURES
3-1
Fig. 1 Panel Cut-out Dimensions
3-4
Fig. 2 Power Input Connections for the -L Option
4-3
Fig. 3 Probe Dimensions
5-2
Fig. 4 IEEE-4888 Standard Connector
5-2
Fig. 5 Location of IEEE-488 Board Switches
5-5
Fig. 6 A Typical IEEEE-488 System
LIST OF TABLES
Table 1 Internal DIP Switch Functions
3-5
Table 2 Analog Output Connector Pin Assignments
3-5
Table 3 IEEE-488 Connector Pin Assignments
5-1
Table 4 IEEE-488 Board DIP Switch Functions
5-3
Table 5 String Terminator Switch Settings
5-4
Table 6 IEEE-488 Command Codes
5-8
Table 7 DTM-133-_G IEEE-4888 Command Codes
5-12
Table 8 DTM-133-_G Commands - alphabetic listing
5-13
Table 9 DTM-133-_G Commands - listing by function
5-16
DTM-133 User’s Manual Contents -1

Contents -2 DTM-133 User’s Manual

1. GENERAL DESCRIPTION
The DTM-133 Digital Teslameter offers accurate measurement of magnetic flux density, with direct digital readout
in tesla or gauss. The instruments are light and compact, and the probes are easy to use. The DTM-133 has been
engineered to withstand the severe electrical interference produced by high voltage discharge.
Options provide serial communications (RS-232C and fiber optic) or IEEE-488 interfacing for system applications.
FEATURES
Measures magnetic fields over four ranges up to 3 tesla with polarity indication; resolution up to 1 part in 6000
Range selection is manual or by selectable auto-ranging
Used with special miniature Hall probe - easy to attach to magnet pole or other hardware. Probe holders are
available as optional accessories.
Accuracy and temperature specifications include total system performance, probe and instrument. This is the only
meaningful indication of measurement accuracy.
Probe is calibrated with field characteristics stored in memory chip contained in cable plug.
Accuracy is better than +0.03% for the complete system probe and instrument.
Temperature coefficient is better than 100ppm/”C for the overall system.
Accuracy is verified against nuclear magnetic resonance (NMR) standard.
Probe calibration is verified at many field points on every probe, and a printed calibration table is supplied with every
probe.
Front panel keys select the desired field range and invoke the peak hold function to read the peak field value. The
keys are also used to reset the peak hold to zero the system, and to switch on auto-ranging. Peak hold is
implemented digitally, has zero sag
Digital filtering of the displayed field reading suppresses short-term fluctuations. The filtering characteristic is non-
linear; small field variations within a narrow window centered on the currently displayed value are filtered; large
field changes are displayed immediately. Filter window and time-constant may be changed by remote command
when serial or IEEE-488 option is fitted. Filtering is switched internally.
DTM-133 (GPIB) User’s Manual 1-1

With digital communications, the DTM-133 can deliver 30 readings per second.
Two digital communication options: serial (RS-232G and fiber optic) and IEEE-488 General Purpose Interface Bus.
With the serial option, a single teslameter may be connected to standard RS-232C equipment, or up to 31 units may
be interconnected on the Group3 Communication Loop (G3CL) and driven from computer or terminal.
Fiber optic ports duplicate functions of RS-232C signals, for electrical noise immunity and voltage isolation. Fiber
optic links may be up to 60 meters in length using Hewlett- Packard HFBR-3500 series improved fiber optic cables.
The IEEE-488 option fully supports all relevant GPIB functions and commands. including full talker-listener capability.
serial and parallel polling, service request, and talker-only.
ASCII control commands are accepted to modify the output data format to change the rate of data transmission or
to request transmission of a single field reading. Other commands select the field range. select and peak hold
functions turn on and off digital filtering and modify the filter characteristics. System status may be determined
remotely.
The system can be operated in triggered mode where field measurements by one or more teslameters are triggered in
synchronism with each other by external command.
Internal switches select serial data format and baud rate device address, string terminators, filtering, field units in
gauss or tesla, data format service request action, EOI action and perform system reset.
An analog output gives instantaneous field value (0 to 9 kHz) not corrected for probe non-linearity.
Model variations are available without display and keys for true ’black box' magnetic- field-to-computer interfacing.
A panel mount model with display is available.
1-2 DTM-133 User’s Manual

2. SPECIFICATIONS OF A DTM-133 SYSTEM
Measurements Field
magnetic field density in tesla or gauss
ranges
0.3
0.6
1.2
3
tesla full-scale,
3
6
12
30
kilogauss full-
scale,
with polarity indication and selectable auto ranging maximum
calibrated field
+2.2 tesla +22 kilogauss
Resolution
1 in 12,000 of bipolar span with digital filtering on
ranqe
resolution
gauss
tesla
0.3 tesla
0.5
0.00005
0.6 tesla
1
0.0001
1.2 tesla
2
0.0002
3.0 tesla
5
0.0005
Accuracy
DTM-133 with LPT-130 or MPT-132 probe:
+(0.03% of reading + 0.03% of full-scale) max at 25°C
Temperature stability
DTM-133 with LPT-130 probe:
caIibration: -100 ppm of reading/'C max. add -3ppm/°C for
each meter of probe cable
zero drift: +(8 microtesla + 0.0015% of full-scale)/°C max
Temperature stability
DTM-133 with MPT-132 probe:
calibration:
-100 ppm of reading/°C typical
-140 ppm of reading/°C max. add -
3ppm/°C for each meter of probe cable
zero drift:
+(15 microtesla + 0.0010% of full-scale)/ °C typical
+(40 microtesla + 0.0015% of full-scale)/ °C max.
Time stability
+0.1% max. over 1 year
Measurement rate
30 fully corrected measurements per second
Display rate
10 display updates per second
Response time
full-scale change of field reading settles to within resolution
in less than 0.2 second (filtering off - see below)
Peak hold mode
displays maximum field since mode entered or reset
peak hold is implemented digitally with zero sag or decay
DTM-133 User’s Manual 2-1

Probes standard sensitivity transverse types: LPT-130 , MPT-132
high sensitivity transverse types: LPT-230, MPT-230
2-2 DTM-133 User’s Manual
Display Indicators
7-character 7-segment alphanumeric display
8 back-lit legends for:
0.3, 0.6, 1.2, or 3.0 tesla range selected,
peak hold mode on, digital filtering on, tesla/gauss units
Display modes
field, peak hold field
Digital filtering
field value filtering smooth’s out small fluctuations in the reading;
large, rapid field changes are not filtered; internally switch selected.
Keys
2 keys select range, access peak hold display, load defaults
zero field display, reset peak hold, select auto-ranging,
Analog output
instantaneous field analog:
full-scale output: +3V nominal source
impedance: 1000a accuracy: I-10%
bandwidth: 9kHz at -3dB, roll-off 3-pole 60dB/decade
On-board switches
digital filtering on/off, units (tesla or gauss)
Memory backup
user-entered data stored indefinitely in non-volatile memory
Power source
DTM-133
DTM-133-_S
DTM-133-
_G
ac:
min
8V
0.65
0.75
1.1
A rms
Max
15V
0.3
0.35
0.5
A rms
dc:
min
10V
0.45
0.5
0.75
A dc
Max
19V
0.17
0.2
0.3
A dc
(because a switchmode regulator is used, input current falls as the voltage rises)
ac line input plugpack supplied.
Power fuse on processor board: 1amp anti-surge 5 x 20mm
To obtain maximum spark protection, use PS12D7 power supply
and ferrite kit 11000036. See section 3.8.
L option: 115/208/230 V ac power input.
Enclosure
aluminum, 217 x 125 x 50 mm, textured finish, charcoal grey color,
tilt stand fitted to bench models
Ambient field
Maximum operating field for electronics package:
10 millitesla with single-range probe,
0.5 millitesla with multi-range probe.
Temperature range
0 to 50°C operating, absolute maximum temperature of probe 60°C
Instrument weight
1.2 kg,
shipping weight:
2.5 kg

Additional specifications with communication options
Digital interfacing serial option: RS-232C and fiber optic;
parallel option: IEEE-488 General Purpose Interface Bus
System orientation Group3 Communication Loop (G3CL) using serial ports,
simple loop for 31 devices no multiplexer required:
GPIB with IEEE-488 option.
Digital data format ASCII input commands and output responses
Commands requests for field value; setting and inspection of display and control modes;
field measurement triggering; entry of numerical values; setting units. output data format,
and filter characteristics; test commands
Output responses field value in tesla or gauss followed by optional T or G and carriage return/line feed:
numerical and system status data requested by commands: messages
Serial bit rate 16 standard rates. switch selected, 50, 110, 134.5 1 TO, 200, 300,
600 900, 1050, 1200, 1800, 2000 2400. 4800. 9600, 19200 baud
Fiber optic cable Hewlett-Packard HFBR-3500, 60 meters max
IEEE-488 functions SH1 source handshake capability
AH1 acceptor handshake capability
T5 talker (basic talker, serial poll, talk-only mode, unaddressed to talk if addressed to
listen)
TE0 no address extension talker capability
L4 listener (basic listener, unaddressed to listen if addressed to talk)
LEO no address extension listener capability
SR1 service request capability
RLO no remote local capability
PP1 parallel poll capability (configured by controller)
DC 1 device clear capability
DT1 device clear capability
CO no controller capability
GPIB connector standard Amphenol 57-20240 with metric standoffs
DTM-133 User’s Manual 2-3

ORDER CODES
Basic teslameters,
capable of four measurement ranges 0.3, 0.6, 1.2, 3.0 tesla full scale,
0.03, 0.06, 0.12, 0.3 tesla full scale for high sensitivity probes
support all LPT and MPT series probes, plugpack supplied except for option -L.
DTM-133 (recommended probes are LPT-130, LPT-230, MPT-132, MPT-230)
Options
Bench styleinstrument withdisplay: addsuffix -D
Panel-mount version: addsuffix -P
Withoutdisplay,plugpack powered: addsuffix-N
Without display, line voltage power: add suffix -L
Serial data input/output, RS-232C & fiber optic: add suffix-S
IEEE-488 GPIB capability: add suffix G
Example: DTM-133-DS
Probes
Four ranges, standard 2-meter cable
LPT-130
| standard sensitivity
LPT-230
| high sensitivity
MPT-132
| probes
MPT-230
| probes
Single range probes: add range suffix -03, -06, -12,-30.
Special probe cable lengths: add length suffix -XMor -XS,
forXsubstitutecablelengthinmeters, 30max.
M denotes unshielded cable; Sdenotesshieldedcable.
Example: LPT-130-2S
Accessories
fiber optic cable fitted with connectors,
60-meter length maximum
probe holders
fiber optic repeater, bidirectional, model FOR-2PP
fiber optic to RS-232C adaptor, model FTR
serial/GPIB adaptor, model COM-488
digital display for remote control & readout of field values, model DPM
rack panels, 3.5 inches high (2U), for rack mounting 1, 2, or 3 DTMs or DPMs
ferrite kit 11000036 for spark protection
power supply PS12D7 for spark protection
2-4 DTM-133 User’s Manual
One of these options
must be specified
Must select
one option