Pyramid T-1 User manual

T-1
Web-enabled Precision Hall Probe
User Guide
Pyramid Technical Consultants, Inc.
135 Beaver Street Suite 102, Waltham MA 02452 USA
US: TEL: [phone]  FAX: [phone]  EMAIL:
[email protected]
Europe: TEL: [phone]

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1 Contents
1 Contents .............................................................................................................................................................. 2
2 Introduction ........................................................................................................................................................ 4
3 What’s in the box? ............................................................................................................................................. 5
4 Safety Information ............................................................................................................................................. 6
5 Intended use ........................................................................................................................................................ 6
6 Operating environment ..................................................................................................................................... 6
7 Getting started .................................................................................................................................................... 7
7.1 Connecting the parts ....................................................................................................................................... 7
7.2 Connecting to a network.................................................................................................................................. 7
7.2.1 Connecting using a static IP address ...................................................................................................... 8
7.2.2 Connecting using DHCP address assignment ...................................................................................... 10
8 The web browser GUI ...................................................................................................................................... 13
8.1 Data display and controls ............................................................................................................................. 13
8.1.1 Sampling rate ....................................................................................................................................... 14
8.1.2 Measurement range .............................................................................................................................. 14
8.1.3 Zero offset ............................................................................................................................................ 15
8.1.4 Plotting control .................................................................................................................................... 15
8.1.5 Temperature ......................................................................................................................................... 15
8.1.6 Exporting data ...................................................................................................................................... 16
9 Making measurements ..................................................................................................................................... 18
9.1 Mounting the probe ....................................................................................................................................... 18
9.2 Cable length .................................................................................................................................................. 19
9.3 Sampling rate and measurement range ......................................................................................................... 19
10 Using your own software ................................................................................................................................. 22

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10.1 Example Python script to collect a specified number of readings from the T-1 ....................................... 22
10.2 Example Python script to display the field in large text ........................................................................... 24
11 Monitor output ................................................................................................................................................. 26
12 Utilities .............................................................................................................................................................. 29
12.1 Software updates ...................................................................................................................................... 29
12.2 Device name ............................................................................................................................................. 30
12.3 Rebooting .................................................................................................................................................. 30
12.4 Changing network settings ....................................................................................................................... 30
12.5 Accessing support ..................................................................................................................................... 31
13 Some background about magnetic measurements ........................................................................................ 32
13.1 Measures of Magnetic Field Strength ....................................................................................................... 32
13.2 Field vectors ............................................................................................................................................. 33
13.3 Rate of Change of Magnetic Flux Density ................................................................................................ 33
14 Fault-finding ..................................................................................................................................................... 35
15 Maintenance ..................................................................................................................................................... 38
16 Returns procedure ........................................................................................................................................... 39
17 Support.............................................................................................................................................................. 40
18 Disposal ............................................................................................................................................................. 41
19 Revision history ................................................................................................................................................ 42

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2 Introduction
Thank you for your purchase of the T-1 Precision Hall probe system. The T-1 allows fast and accurate
measurements of magnetic flux density from a compact and cost-effective unit. The active HP-1 probe is made from
non-conducting materials to eliminate eddy current effects and uses tightly twisted signal lines and differential
signals to give excellent noise immunity. An integrated sensor measures temperature right at the Hall element to
provide accurate temperature compensation of the field reading. The standard configuration of T-1 and HP-1 probe
allows fields up to +/- 28 kGauss (+/- 2.8 Tesla) to be measured at rates between 10 Hz and 25 kHz.
The T-1 control unit provides a standard network connection for control and readback to allow simple integration
into control systems. The analog voltage output can be used to monitor the measured field via a meter, oscilloscope
or digitizer.
Multiple T-1 units can be distributed to monitor magnetic field in multiple locations, and all communicate with a
supervising computer system. The T-1 has a web page interface allowing any standard web browser to display the
measurements. It is also easy to collect the data into your own software.
This User Guide provides the information you need to start making measurements with the T-1. More detailed
information is provided in the T-1 Technical Manual.

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3 What’s in the box?
Unless your order was for a special configuration, you should have received the items shown below. If anything is
missing or damaged, please contact your supplier.
T1 control unit
HP-1 active Hall probe
Connecting cable (part CAB-T1-6)
Ethernet cable
Universal power supply (part PSU24-25-1)
Calibration certificate and connection information sheet
USB drive with documentation and software
The line cord for the power supply can be selected to suit your local mains
connector type at time of order. The connector on the power supply end of the
cord is an IEC C7 two conductor type.

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4 Safety Information
The T-1 and HP-1 probe are designed for compliance with harmonized electrical safety standard EN61010-1:2000.
They must be used in accordance with the specifications and operating instructions. Operators of the unit are
expected to be qualified personnel who are aware of electrical safety issues. The customer’s Responsible Body, as
defined in the standard, must ensure that operators are provided with the appropriate equipment and training.
The unit is designed to make measurements in Measurement Category I as defined in the standard.
The T-1 does not itself generate high voltages or magnetic fields. However, your
application may involve measuring high fields in electromagnets and high voltages
may present on electromagnet coils.
Take special care when making measurements where high fields or voltages are
involved.
The T1 must not be operated unless correctly assembled in its case. Only Service Personnel, as defined in
EN61010-1, should attempt to work on the disassembled unit, and then only under specific instruction from Pyramid
Technical Consultants, Inc. or their authorized distributors.
The T-1 unit is designed to operate from +24 VDC power, with a maximum current requirement of 250 mA. The
HP-1 probe is powered by the T-1. A suitably rated power supply module is provided.
When installed in a permanent location, the T-1 unit should be grounded by secure connection to a grounded
conducting surface. If the unit is mounted on an insulating surface, then one of the four mounting screws must be
re-assigned as a grounding connection. An adaptor for DIN-rail mounting is available.
5 Intended use
The T-1 is intended for magnetic flux density measurement, particularly in electromagnets in networked systems.
The field can be monitored at rates suited for real-time monitoring and field control. The probe design eliminates
magnetic materials or conducting surfaces that would distort the measurement of AC fields. The HP-1 probe is
particularly suited to measure the magnetic fields typical of ion beamlines which use conventional (non-
superconducting) electromagnets and has the range and precision to perform well in many general field
measurement applications. The probe is thin (less than 2.5 mm) but nevertheless stiff enough to allow it to be
placed at a known and stable location in the field.
6 Operating environment
The T-1 and HP-1 probe have design features which make them tolerant of electrically noisy environments, but the
place of use is otherwise assumed to be clean, sheltered and with a relatively small temperature range. The probe is
tolerant of a moderate radiation background such as might be found along a particle accelerator beamline.
The T-1 has good precision combined with low levels of drift and aging. Nevertheless, for maximum accuracy in
critical applications, the T-1 and probe should be re-calibrated every 1-2 years against a traceable reference.

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7 Getting started
In order to read a magnetic field with the T1, you must assemble the components and then open
the web browser to see the readings.
7.1 Connecting the parts
1) Find the cable that joins the T-1 to the HP-1 probe and connect each end. There is a standard
9-pin DSub connector on the T-1 and a micro D connector on the probe.
2) Plug the line cord into the power supply (the green LED on the supply will illuminate) and
connect the threaded jack connector to the T-1. Connect to the line (110-240 VAC, 50-60 Hz)
and check that the white LED on the T-1 illuminates.
You are now ready to connect to a network.
7.2 Connecting to a network
The T-1 connects to a wired network using a standard Ethernet RJ-45 port. It needs an IP4
address on your network. IP4 addresses look like this: “192.168.100.123”, with each group of
numbers limited to the range 0 to 255. In typical local networks the first three groups of
numbers are the same and define a “subnet”.
The last group of numbers are available for devices on the local subnet. Since 0 and 255 are
reserved broadcasts and for devices like routers, that means the T-1 will need a number in the
range 1 to 254. There are two ways to set this up. “DHCP” (Dynamic Host Configuration
Protocol) is where a DHCP server on the network, usually a router, assigns an available address.

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This address is not fixed and may be changed by the router when the T1 makes a new connection
to the network. Static addresses on the other hand are set by the user and do not change. Static
addresses are more usual in technical networks.
The T-1 is normally supplied set up with a specific static IP address. This address is given on the
configuration sheet supplied with the unit. However, you can request a specific static address to
be set and enabled when you place your order. You can also change the address once you are
connected, or you can set the T-1 for DHCP address assignment.
7.2.1 Connecting using a static IP address
We recommend starting with the simplest communication setup. Make a direct connection from
a computer to the T-1 with a standard Ethernet patch cable.
Since there is no router in this setup, you will need to set the IP address of the computer. The
factory setting is shown on the connection sheet included with the product. If the static address
of the T-1 is 192.168.1.44 for example, choose a setting in the same subnet apart from .44. For
example, here are the Microsoft Windows dialogs for setting the computer to 192.168.1.100:
1. Edit the properties of the
Ethernet adaptor.

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2. Edit the TCP/IPv4 Properties
3. Select “Use the following IP
address” and enter the IP address.
Set the Subnet mask as shown.
Click “OK” and then “Close” to
close the dialogs and make the
new address effective.
If you look at the amber and green LEDs on the T-1 Ethernet port and the cable is connected,
you will see the amber light on and the green flickering when the T-1 is communicating. Now
open a web browser such as Chrome, Edge, Firefox, Safari and type the static address of the T-1
into the URL field. The T-1 will deliver its web page showing the measured field, a graph of the
field against time and various controls.

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7.2.2 Connecting using DHCP address assignment
The local network must have a router to use this method. Using a standard Ethernet patch cable,
connect the T-1 to the router or to a switch on the network.
Switch
Router

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To allow the T-1 to get an address from the router, it must be setup for DHCP. Open the
“Network <···>” dialog from the link at the bottom of the T-1 web page:
Set the DHCP control on and click “Apply ”.
Now when you reconnect to a network with a router, the T-1 will be assigned a new IP address.
You need to discover this address in order to access the T-1 web page. There are various
software utilities that allow a whole subnet to be searched. You can also log in to the network
router and look for the T-1 in its table of connected devices. In Windows you can use the MAC
ID to find the IP address. The MAC ID of the T-1 can be found on the connection information
sheet supplied.
If you are using a Windows computer, open a command prompt by entering “cmd” into the
Windows search box. If the MAC ID starts with fc-69 as an example, type in the command
arp -a | Find “fc-69”
The result will be a list of IP addresses for devices on the network with MAC IDs that start with
fc-69. If there are multiple addresses in the response, use more of the MAC ID string to narrow
the search.

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On Linux systems the arp command is part of the net-tools package, which you may need to
install in it is not present in the distribution you are using. The terminal command
arp -n
will
return a list of IP addresses that are assigned to the MAC IDs of devices in the network address
table.
Now you have the IP address of the T-1 you can enter it in the url field of a web browser to open
the T-1 web page.
TIP
On some networks the T-1 may fail to make network a connection first time. Generally re-
connecting the Ethernet cable or disconnecting and reconnecting the power to the T-1 will allow
the connection to be established.
TIP
If you have set DHCP addressing and connect the T-1 and the computer to a network with no
router, the T-1 will use its static address setting. A direct connection is a case of this type of
network.

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8 The web browser GUI
The T-1 will provide its web page to any browsers on the network. This can include Windows.
Linux, MacOS and Android systems. It can serve multiple browsers at the same time on
multiple client computers.
8.1 Data display and controls
The T-1 web GUI displays the magnetic field in units of Gauss. To convert to units of Tesla,
divide the readings by 10,000. The T-1 is simple to operate with only two settings that affect
data acquisition. The first is the sampling rate and the second is the measurement range.
NOTE
The T-1 always starts up with the same settings it was using before it was shut down.

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8.1.1 Sampling rate
The maximum measurement rate that the T-1 supports is 25,000 samples per second, or one
every 40 microseconds. Lower rates can be selected down to 10 samples per second, or one
every 100 milliseconds, and this is achieved by averaging multiple readings. Simply click on the
required sampling rate and it changes immediately.
As is usual with any type of measurement, you need to choose the best compromise between
sensitivity to fast changes in the measurement and the signal to noise ratio. The section later in
this manual about sampling rate shows how this tradeoff works.
TIPS
Use low sampling rate to make precise measurements of static or slowly changing magnetic
fields.
Use high sampling rates to see fast changes in magnetic fields.
Use 10 Hz sampling to remove any effect of line voltages (50 or 60 Hz) on the readings.
8.1.2 Measurement range
The standard HP-1 active probe supplied with the T-1 measures up to +/- 28 kGauss, which is +/-
2.8 Tesla. Three more sensitive ranges are provided for measuring smaller fields, +/-7.0 kGauss
(0.7 T), +/-2.8 kGauss (0.28 T) and +/-700 Gauss (70 mT). If the field exceeds the range, the
displayed reading changes from blue to orange when the nominal full scale is exceeded, and red
when the reading is saturated. This is illustrated below for the 2.8 kGauss range.
Valid reading
Nominal range exceeded
Saturated
CAUTION
A high magnetic field may be present but hidden by saturation. Check the colour of the
displayed field reading and use the 28 kGauss range when necessary to ensure the reading is not
saturated.
NOTE
You will only encounter fields above 28 kGauss if your work involved superconducting magnets.
Probes with higher field capability are available for the T-1.

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8.1.3 Zero offset
If you want to measure a small field, or a small change in a larger field, it is helpful to remove
the offset so you can focus on the small change. Clicking the “Zero” button stores the most
recent reading and subtracts it from subsequent readings. The value being subtracted is
displayed.
The zero offset is applied to all client computers watching the T-1. To return to normal
measuring, click “Clear”.
CAUTION
A high magnetic field may be present but hidden by zero offset. If in doubt, click “Clear” to
remove the offset.
TIP
You can edit the offset value directly if you need to suppress a known background field.
8.1.4 Plotting control
The measured field is plotted continuously against time on an autoscaling graph. Up to 1000
readings are plotted. Once 1000 readings are in the data buffer, the oldest readings will be
discarded as new readings come in. You can freeze the plot with the Hold button:
and resume with the start button .
You can clear the data buffer and the graph and start it filling again with the Clear button:
.
If you are using a low sample rate, it takes longer for the buffer to fill.
TIP
If you pause the plotting on one client computer, this will not affect the graphs on other
connected computers. If you change the measurement conditions such as range, sample rate or
zero offset, this affects the T-1 itself and therefore shows on all connected devices.
8.1.5 Temperature
The HP-1 probe includes a temperature sensor at the probe tip and the reading is shown on the
web browser screen. The readings are corrected for temperature however best accuracy will be
achieved if the temperature is closer to the initial factory calibration temperature which is in the
range 20 to 25 C.

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8.1.6 Exporting data
Clicking the Export button
freezes the data buffer and opens a dialog that allows you to store the buffer contents in csv
format. The resulting file can be opened by any software that can read a csv format file, such as
a spreadsheet program. The dialog box shows a sample of the buffer and allows you to rename
the file, and change the numeric format of the field readings and the format of the timestamps.

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NOTE
The T-1 gets the current date after a reboot if it can connect to a time server over the internet. If
it cannot connect, it sets the current date to the start of year 2000 as a default. Remember this if
you are use timestamps with the full date.
NOTE
The graph on the T-1 screen is plotted back in time from right (the most recent value) to left.
The exported data is listed in increasing time order. To match the screen display you would need
to plot the exported data the same way.

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9 Making measurements
9.1 Mounting the probe
The HP-1 probe should be mounted so that the sensitive spot is located in the field you want to
measure. Two clear holes for M4 screws are provided on the probe mounting flange to allow a
stable position. The probe will measure the field component normal to the flat of the target spot
graphic. The Hall element is under the red cross hair. It has a sensitive area of about 1.5 mm
2
.
The field reading will be a positive value for a magnetic field vector entering the top surface of
the probe, as shown below.
N
S
The probe mounting should prevent any tendency for movement or vibration, especially if the
probe is measuring a fringe field where there is field curvature. If the field has significant AC
components, the mounting should be non-conducting to avoid measurement errors due to eddy
currents. The HP-1 probe itself is designed to make AC measurements: there are no metal
components to support eddy currents and the low-level signals are carried in tightly twisted
conductors.

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9.2 Cable length
The HP-1 probe includes active electronics that boost the signal from the Hall element and send
it to the T-1 in differential form. This permits a relatively long connection which may be helpful
for some installations.
The standard probe cable is 6 foot (1.8 m) long. To increase the cable length, simply add a good
quality 9-way screened cable terminated in a 9-pin DSub male at one end and 9-pin DSub female
at the other. The cable should have all nine ways connected pin to pin. This type of cable is
readily available pre-made in various lengths. The connection from the extension cable to the
probe cable can be secured using 4-40 UNC threaded spacers.
The Ethernet connection from the T-1 can of course be very long if needed.
9.3 Sampling rate and measurement range
When investigating an unknown signal it is a good idea to look at with different sampling rates
to see if there are AC components to the signal. But for a specific measurement application you
will want to use the optimum sampling rate and range. The following example show the effect
they have on measurements.
250 readings of a permanent magnet field of 6.155 kGauss were taken on the 7 kGauss range
with different sampling rates. Note the following:
- The reading becomes less and less noisy as the sampling rate reduces, due to the averaging.
- The amount of time covered by the 250 readings changes from 10 msec to 25 seconds.
- It is possible to reproduce the low sampling rate data if you export the high sampling rate data
and then average it with other software. However, this would require a lot of readings to be
collected and analysed. To re-create the 10 Hz data, you would need to process 625,000
readings.

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6153.50
6154.00
6154.50
6155.00
6155.50
6156.00
6156.50
0.000 0.002 0.004 0.006 0.008 0.010
25 kHz sampling
6153.50
6154.00
6154.50
6155.00
6155.50
6156.00
6156.50
0.00 0.05 0.10 0.15 0.20 0.25
1 kHz sampling
6153.50
6154.00
6154.50
6155.00
6155.50
6156.00
6156.50
0.00 0.50 1.00 1.50 2.00 2.50
100 Hz sampling
6153.50
6154.00
6154.50
6155.00
6155.50
6156.00
6156.50
0 5 10 15 20 25
10 Hz sampling
A quantitative to way to look at the effect of the effect of the averaging at different sampling
rates is to look at the standard deviation of repeat readings. For the results in the plots above the
standard deviation goes from 0.012% of the field reading down to 0.0005% (5 ppm) as the
sampling rate is reduced from 25 kHz to 10 Hz.
The excellent precision and stability of the Hall device and the analog circuitry means that the
resolution of the digitization by the T-1 can appear in the results under some measurement
conditions, particularly if the measured field is very stable.
The T-1 analog to digital converter has 16 bit resolution, or 15 bits for each of positive and
negative polarity fields. For the example data below, the range setting for the permanent magnet
measurement was changed from 7 kGauss to 28 kGauss. This means the digitization steps
changed from 0.21 Gauss to 0.85 Gauss, and this is evident in data taken of stable fields at high