CMA Dishmachines MAGNETIC FIELD SENSOR BT52i User Manual

MAGNETIC(FIELD%SENSOR!BT52i!

USER’S!GUIDE!

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CENTRE FOR MICROCOMPUTER APPLICATIONS

http://www.cma-science.nl

2!|!BT52i!Magnetic!Field!Sensor!User’s!Guide!!

Short!description!

The!Magnetic! field!sensor!BT52i!measures!magnetic! field!strength.! It!has! two! measurement!
ranges,!-100!..!500!mT!and!-10!..!50!mT,!which!can!be!selected!using!a!push!button!located!on!
the!top!of! the!sensor!box.! When!the!push! button!is!pressed!down,!the!range!-10! ..!50!mT! is!
selected,!when!the!push!button!is!in!the!upper!position,!the!-100!..!500!mT!range!is!selected.!
The!Magnetic!field!sensor!uses!a!Hall-element!as!its!sensing!element.!This!element!is!mounted!
at!the! tip! of! the! stainless! steel! tube,! at! the! position! 0! cm! indicated!on! the! metal! tube.! The!
face!of!Hall!element!is!directed!perpendicular!to!the! direction!of!the!stainless!steel!tube!and!
the!sensor! is!most!sensitive!when!the!metal!tube!is!positioned!parallel!to!magnetic!field!lines.!
The! sensor! is! therefore! very! suitable! for! measuring! the! magn etic! field! inside! coils,! or! near!
(very!strong)!permanent! magnets.!The! sensor!is!less! suited!to! measure!the!magnetic!field! in!
slit-shaped! cavities.! Because! the! output! signal! of! a! Hall-element! is! very! small,! th e! Hall­element! is! co ntained ! in! an! integrated! circuit! with! a! differential! amplifier! with! temperature!
compensation!in!order!to!get!a!good!quality!output!signal.!

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Note:!The!values!obtained!by!the!sensor!will!be!sensitive!to!the!position!in!the!magnetic!field!
and!the!orientation!of!the!sensor!to!the!field!direction.!!A!false!low!value!could!be!achieved!if!
the!direction!of!magnetic!field!is!not!parallel!to!the!direction!of!the!sensor!tube.!!

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The!CMA!Magnetic!Field!sensor!BT52i!can!be!directly!connected!to!the!analog!BT!inputs!of!the!
CMA!interfaces.!The!sensor!cable!BT!-!IEEE1394!needed!to!connect!the!sensor!to!an!interface!
is!not!supplied!with!the!sensor!and!has!to!be!purchased!separately!(CMA!art.!code!BTsc_1!or!
BTsc_4!).!!

Sensor!recognition!

The! Magnetic! Field! sensor! BT52i! has! a! memory! chip! (EEPROM)! with! information! about! the!
sensor:! its! name,! measured! quantity,! unit! and ! calibration.! Through! a! simple! protocol! this!
information!is!read!by!the!CMA!interfaces!and!the!sensor!is!automatically!recognized!when!it!
is!connected!to ! these!interfaces.! !Each!measurement! range!of!the! Magnetic!field!sensor! has!
its!own! EEPROM!information.!The!position!of!the!push!button!determines!which!information!
is! used.! To! be! able! to! detect! to! which! of! the! ranges! the! sensor! is! set! first! disconnect! the!
sensor! from! an! in terface,! select! the! desired! measurement! range! with! the! push! button! and!
then!connect!the!sensor!to!the!interface!again.!!
If! your! Magnetic! Field! sensor! is! not! autom atically! detected! by! an! interface! you! have! to!
manually!set!up!your!sensor!by!selecting!it!from!the!Coach!Sensor!Library.!!

Calibration!!

The!CMA!Magnetic!Field!sensor!BT52i!is!supplied!calibrated.!The!output!of!the!sensor!is!linear!
with!respect!to!the!magnetic!field!strength.!The!supplied!calibration!functions!are:!

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! ! ! -10!..!50!mT!range:!! ! ! B!(mT)!=!50!*!V

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!(V)!-!10!

! ! ! -100!..!500!mT!range:!!! ! B!(mT)!=!500!*!Vout!(V)!-!100!

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The!Coach!software!allows!selecting!the!calibration!supplied!by! th e!sensor!memory!(EEPROM)!

BT52i!Magnetic!Field!Sensor!User’s!Guide! |!3!

or!the!calibration! stored!in! the!Coach!Sensor!Library.!The! Coach!program! allows!shifting!the!
pre-defined!calibration!or!creating! a!new!calibration! if!needed.!Use! the!Set!to! zero!option!in!
Coach!to!adjust!the!zero!point!of!the!sensor.!!

Suggested!experiments!!

The!Magnetic!Field!sensor!can!be!used!in!various!experiments!such!as:!

• Measurements!of!the!magnetic!field!near!a!(strong)!permanent!magnet.!

• Measurements!of!the!magnetic!field!near!a!current-carrying!wire.!

• Measurements!of!the!magnetic!field!near!or!inside!a!coil!or!solenoid.!

• The!variation!of!the!field!when!alternating!current!flows!through!a!coil.!

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Figure.!Measuring!the!magnetic!field!near!a!permanent!magnet.!

Magnetic!field!strength!measurement!!

Magnetic!field!strength!(also!known!as!the!magnetic!flux!density)!is!a!measure!of!the!force!the!
magnetic!field!will!exert!on!an!electric!current!or!another!magnet.!!
In! S.I.! units! magnetic! field! strength! is! expressed! in! teslas! (T).! In! cgs! units! magnetic! field!
strength!is!expressed!in!gauss!(G).!!

1!G!=!1!x!10

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!T!=!0.1!mT!and!1!mT!=!10!G!

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Below!are!given!magnetic!field!strength!values!of!exemplary!magnetic!sources.!

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Magnetic!field!strength&

in!mT&!

Magnetic!field!source!

10

-10!

–!10-9!!

The!human!brain!magnetic!field!

0.031!-!0.058!

The!Earth’s!magnetic!field!on!its!surface!

2,5!

The!Earth's!magnetic!field!in!its!core!

5!

A!typical!refrigerator!magnet!!

10!

A!small!iron!magnet!!

200!

A!small!neodymium-iron-boron!(NIB)!magnet!!

1500!-!3000!!

A!medical!magnetic!resonance!imaging!electromagnet!!

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4!|!BT52i!Magnetic!Field!Sensor!User’s!Guide!!

Technical!Specifications!
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Sensor!kind!

Analog,!generates!an!output!voltage!between!0!..!5!V !

Measurement!ranges!

-10!..!50!mT!

-100!..!500!mT!

Resolution!using!!
12!bit!AD!converter!

-10!..!50!mT!range:!0.024!mT!!

-100!..!500!mT!range:!0.24!mT!

Calibration!function!

-10!..!50!mT!range:!B!(mT)!=!50!*!V

out

!(V)!-!10!

-100!..!500!mT!range:!B!(mT)!=!500!*!Vout!(V)!-!100!

Accuracy!!

±!5!%!

Voltage!offset!!

0.5!V!±!3%!

Current!requirement!

Max.!60!mA!

Operating!
temperature!

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0!..!50!°C!

Connection!

IEEE1394!connector!for!BT-IEEE1394!sensor!cable.!!
Sensor!cable!is!not!delivered!with!the!sensor!and!has!to!be!

purchased!separately!(CMA!art.!code!BTsc_1!or!BTsc_4!).!!

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Warranty:!!

The! Magnetic! Field! sensor! BT52i! is! warranted! to! be! free! from! defects! in! materials! and!
workmanship! for!a!period!of!12!months!from!the!date!of!purchase!provided!that!it!has!been!
used!under!normal!laboratory!conditions.!This!warranty!does!not!apply!if!the!sensor!has!been!
damaged!by!accident!or!misuse.!!
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Note:! This! product! is! to! be! used! for! educational! purposes! only.! It! is! not! appropriate! for!

industrial,!medical,!research,!or!commercial!applications.!! ! ! ! !

Rev. 01/10/2017