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

out

!(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)!