bourns ? model ems22 non-contacting magnetic encoder sensors & controls product brochure
bourns? model ems22 product description bourns? model ems22 is a non-contacting rotary magnetic encoder with a hall efect application- specifc standard product (assp) capable of producing four distinct output waveforms. tese waveforms include 2-bit quadrature up to 256 ppr*, step/direction up to 512 ppr, pulse-width modulated (pwm) output with 1024 positions, and absolute with 1024 positions. model ems22 is available in both a 3.3 and 5.0 vdc supply voltage and is ofered in two diferent versions. tis product has the capability of rotating up to 10,000 rpm while maintaining code accuracy, making it suitable for mmi applications such as industrial automation. tis performance is achieved by utilizing dual ball bearings in the construction of the device, resulting in extended rotational life up to 100,000,000 shaf revolutions (beyond 100,000,000 shaf revolutions in some confgurations). te ems22 non-contacting encoder is ideal for use in harsh environments where extreme levels of temperature, moisture and particles are present. te outstanding performance of this device is attributed to the non-contacting technology and superior performance of the austriamicrosystems? as5040 hall efect assp. in addition, this product is sealed to ip** 65 with an optional upgrade to ip 67. te ems22 is rohs compliant in accordance with directive 2002/95/ec of the european parliament and council of 27 jan 2003 on the restriction of the use of certain hazardous substances in electrical and electronic equipment. tis model is produced and assembled utilizing state-of-the art production equipment along with lean principles to provide our customers with a high performance product at a competitive price. * pulses per revolution ** ingression protection what is hall efect? discovered by edwin hall in 1879, hall efect refers to the potential diference on opposite sides of a bar-shaped conducting or semi-conducting material (hall element). tis potential diference (voltage) is produced by a magnetic feld applied perpendicular to the hall element through which an electric current fows. figure 1 is provided to clarify this concept by illustration. figure 2 demonstrates two diferent states of the as5040 assp as the magnet rotates in close proximity to the assp. figure 1: hall efect concept
ems22 output waveforms quadrature: tis output waveform is the most common among all contacting and non- contacting encoders. quadrature, also known as 2-bit quadrature or incremental, is ofen used to determine magnitude (count) and direction (up/ down) by an external interface circuit. ems22 comes equipped with such capability; an external interface circuit is not required. it also ofers an indexed output with an adjustable width of one or three times the absolute position value that can be used for counting the shaf rotation. direction/step: tis output is very similar to the quadrature waveform but ofers up to 512 ppr, as opposed to 256 ppr in quadrature. tis output can be used in incremental counting applications where a better resolution is desired. indexing output is also available with a direction/step output waveform. absolute: absolute output refers to the absolute angular position. tis type of output is especially useful for applications where the absolute position of a device, such as a camera, is necessary to locate an object. also with 1024 distinct angular positions, the ems22 ofers very high resolution indexing at every 0.35 . tis type of output code is not afected by a power outage to the encoder since each angular position of the encoder has a unique code. pwm: pulse-width modulation is another form of absolute waveform that utilizes the square wave output generated by the sensor to control the duty cycle of the output at diferent desired shaf positions. te ems22 encoder can generate pulse widths as low as 1 s, and as high as 1024 s in a complete signal period of 1025 s. some advantages of using this output waveform over other output types include immunity to noise and faster data acquisition. figure 2: as5040 assp in two diferent states
how the ems22 rotary magnetic encoder works te ems22 produces a sinusoidal signal by rotation of the magnet in close proximity to the assp, based on the hall efect phenomenon. te sinusoidal signal is then converted to the desired output waveform by the assp that is preprogrammed at the factory to produce one of the output signals below: ? quadrature ? direction/step ? pwm ? absolute figure 3 below shows the steps involved in generating an output signal. shaft is rotated via mmi or hmi rotation of the magnet over the assp produces the sinusoidal signal 3.3 or 5.0 vdc supply voltage is applied to the encoder figure 3: output signal generation steps in ems22 desired output signal is generated via assp
why use an ems22 magnetic encoder? te ems22 can ofer enhanced reliability in harsh environmental conditions such as mud, dust, grease, oil, water and dirt, giving this product an edge in performance over traditional optical and contacting encoders. figure 4 illustrates examples of harsh environments. in addition, there are no contacting parts between the magnet and the assp to degrade the life expectancy of this type of encoder. as a result, the ems22 can have more than 50 times the life expectancy of traditional contacting encoders. te designer and end user can expect cycle life performance without degradation of signal accuracy, a clear advantage over encoders that use optical or contacting technology. figure 4: examples of harsh environments
ems22 features and benefts design engineers with constraints such as cost, space, circuit complexity and resolution will appreciate the unique features and benefts of the model ems22. ems22 non-contacting rotary magnetic encoders can be interconnected in a daisy-chain confguration for a serial read-out option. tis option is benefcial where memory overhead and space for wiring each individual encoder separately is critical in the construction of a control device as illustrated in figure 5. te output of this confguration is the combined output of each individual encoder connected in series to the microprocessor. another great capability of this product is the chip-select option. tis option allows the interrogation of each encoder individually by the microprocessor. unlike daisy-chain, this feature takes less time to execute, ultimately enhancing the speed of the control loop response. if temperature variation is a critical factor in the application, the ems22 ofers excellent performance in a wide temperature range , from - 40 c to + 125 c (- 40 f to + 257 f). tis feature is suitable for applications in extremely cold and hot temperature conditions that can afect the output performance of optical and contacting encoders. designers can choose from a variety of output signals to ft their application needs, whether it is a simple counter, or precision sensing. te ems22 is capable of operating with either a +5.0 vdc supply voltage, or the more energy efcient +3.3 vdc supply voltage. table 1 below provides a comparison of the various technologies, output types, supply voltages, and resolution that can be achieved with each bourns? encoder model family. figure 5: daisy-chain hardware confguration table 1: comparison of various bourns? models micro- processor data input clk chip select data input chip select clk prog. data input ems22 data input chip select clk prog. data input ems22 data input chip select clk prog. data input ems22 bourns? encoder model technology output type(s) supply voltage (vdc) resolution (ppr)/ states* e (e) ontacting solute * e ontacting uadrature em optical uadrature e optical uadrature ems magnetic uadrature ems magnetic irection/step ems magnetic solute/pm *
applications modifcation capabilities typical applications of the bourns? ems22 rotary magnetic encoder with hall efect sensors include but are not limited to: ? audio mixer and broadcasting equipment ? brushless dc motors ? car audio ? car navigation ? cursor position sensing in oscilloscopes ? food processing and packaging ? forklifs and material handling equipment ? gas pedal position sensing ? headlight position controls ? level setting for ultrasound imaging devices ? light dimmers ? marine applications ? medical devices (non-life critical) ? metal cutting saws ? metal working and instrumentation ? ofce equipment: printers, scanners, copiers ? power seating position indicators ? power tools ? pressing and punching machines ? replacement of optical encoders ? replacement of potentiometers ? robotics ? servomotor control ? steering wheel position sensing te ems22 rotary magnetic encoder with hall efect sensor can be customized to suit your application and design needs. tese customizations include but are not limited to: ? analog output to 360 degrees ? brushless dc motor commutation ? custom cable and connectors ? custom shaf and bushing confgurations ? customized electrical angle from 45 to 360 degrees ? high temperature version up to +150 c ? sealed to ip 67 please contact your local bourns sales representative or field application engineer for additional information.
worldwide sales ofces country phone fax benelux: +41 (0)41 768 5555 +41 (0)41 768 5510 brazil: +55 11 5505 0601 +55 11 5505 4370 china: +86 21 64821250 +86 21 64821249 france: +33 (0)2 5473 5151 +33 (0)2 5473 5156 germany: +49 (0)69 800 78212 +49 (0)69 800 78299 ireland/uk: +44 (0)1276 691087 +44 (0)1276 691088 italy: +41 (0)41 768 5555 +41 (0)41 768 5510 japan: +81 49 269 3204 +81 49 269 3297 malaysia (kl ofce): +60 3 71183138 +60 3 71183139 malaysia (penang ofce): +60 4 6581771 +60 4 6582771 singapore: +65 6348 7227 +65 6348 1272 switzerland: +41 (0)41 768 5555 +41 (0)41 768 5510 taiwan: +886 2 25624117 +886 2 25624116 uk/ireland: +44 (0)1276 691087 +44 (0)1276 691088 usa: +1-951-781-5500 +1-951-781-5006 non-listed european countries: +41 (0)41 768 5555 +41 (0)41 768 5510 technical assistance region phone fax asia-pacifc: +886 2 25624117 +886 2 25624116 europe: +41 (0)41 768 5555 +41 (0)41 768 5510 americas: +1-951-781-5500 +1-951-781-5700 www.bourns.com bourns? products are available through an extensive global network of representatives and distributors. to obtain technical applications assistance, a quotation, or to place an order, contact a bourns representative in your area. specifcations subject to change without notice. actual performance in specifc customer applications may difer due to the infuence of other variables. customers should verify actual device performance in their specifc applications. austriamicrosystems is a registered trademark of austriamicrosystems ag in the u.s. and other countries. bourns is a registered trademark of bourns, inc. in the u.s. and other countries. copyright? 2008, bourns, inc. ? litho in u.s.a. ? wag ? 02/08 ? 2m/sc0676
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