Rotary Encoders

Things to know about encoders

Guide for Rotary Encoders

Rotary Encoders

Rotary Encoders with analog or incremental interfaces in single or multiturn versions

Encoders are sensors that use electronics to record angle information in an application and convert it into electrical signals. Optoelectronic and modern technologies based on Hall effect sensors deliver excellent measurement results. In addition, the service life of the sensors is particularly long thanks to the contactless measuring principle. Thanks to the large selection of electrical signal outputs, connections and encoder designs, a large number of variants are available for your application.

A key feature is the angle range that the encoder can detect. Angles up to 360 degrees are covered with single-turn encoders and angles above with multiturn encoders. A distinction must also be made between absolute value output and incremental output. In addition, when choosing the correct product, it is important to pay attention to environmental influences and easy servicing.

Among all the possible parameters, each sensor technology has its own advantages and each sensor has its specific properties, which we would be happy to work out together with your application requirements as part of our advice. In demanding applications, technical product adaptations are often required. MEGATRON is your specialist for these cases and offers the best solutions technically and economically. We support you from the inquiry, through the implementation of the series to the "end of life" of your application with high delivery reliability and assured quality products as a long-term, reliable partner.


50 results found
Rotary encoder ETx25K
Encoder ETx25K with 3D Hall as kit versions
Rotary encoder in compact kit design (8 mm housing depth) with flange mounting and wide variety of electronics and software options in single or multiturn variants
  • Single or multiturn encoder
  • 3D Hall µProcessor with digital signal processing, programmable
  • Analogue, incremental or serial interfaces
  • Housing with very low depth (8 mm)
  • Flange mounting (magnet included)
  • High variety of options and variants
  • Developed and manufactured in Germany
Rotary encoder ETx25F
Encoder ETx25F with 3D Hall for flange and bushing mounting
Rotary encoder with 14.5 mm housing depth for flange and bushing mounting, in single- or programmable multiturn variants, with wide variety of electronics as well as software options
  • As single- or programmable multiturn encoder
  • 3D Hall µProcessor with digital signal processing
  • Analogue, incremental or serial interfaces
  • Low housing depth (14.8 mm)
  • Flange and bushing mounting
  • High variety of options and variants
  • Developed and manufactured in Germany
Rotary Encoder-ETx25-Hall effect
Singleturn Hall effect angle encoders ETA25, ETI25, ETS25, ETP25
Durable rotary encoders with a high number of electronic variants, mechanics and software options
  • Versatile rotary encoder series
  • Various connection possibilities and output signals
  • High quality and durability
  • Short delivery times
  • Engineered and Made in Germany
Hall effect Multiturn Rotary Encoder ETx25
Programmable multiturn Hall effect angle encoder ETA25PM
Customer programmable multiturn rotary encoder up to 72000° in Ø25 mm housing, analogue output and IP66 - for various angles of rotation
  • Only one multiturn rotary encoder device for various demands
  • Angle range and sense of rotation can be parameterized on site
  • High durability
  • Short delivery time
  • Engineered and Made in Germany
Rotary Encoder Hall-Effect-ETA25PS
Parameterizable singleturn Hall effect rotary encoder ETA25PS
Customizable programmable rotary encoders with analogue output – only one rotary encoder for various angles of rotation
  • Only one rotary encoder for various demands
  • Integrated switches for angular range, sense of rotation and voltage supply for on site parameterization
  • High quality and long life
  • Short delivery time
  • Engineered and Made in Germany
Hall effect Multiturn Rotary Encoder HSM22M
Hall effect multi-turn rotary encoder HSM22M
True power-on multi-turn encoder in Ø22.5 mm metal housing detects angles up to 3600° (= 10 turns) absolutely reliable
  • True-Power-On 10 turn (=3600°) Hall rotary encoder
  • Compact Ø22.5 mm housing
  • 5 V, 12 V or 24 V supply voltage
  • Voltage or current output
  • As option with redundant output electronic
Rotary Encoder MAB12A Hall-Effect
Hall-effect absolute encoder MAB12A
Rugged and reliable miniature rotary encoder in Ø12.2 mm housing with ball or sleeve bearing
  • Only Ø12,2 mm housing
  • Sleeve bearing or ball bearing
  • 6 mm, 6.35 mm or 3.175 mm shaft diameter
  • Supply voltage 5 VDC
  • Output signal analog absolute or PWM
  • Integrated MOLEX coupling
Rotary Encoder-Kit-MAB12AH
Hall-effect absolute encoder series MAB12AH
Miniature kit encoder in Ø12.7 mm housing with PWM or analog output
  • Only Ø12.7 mm housing
  • Suitable for Øshaft from 2 mm…6.35 mm
  • Mounting ring and push on magnet are part of delivery
  • Supply voltage 5 VDC
  • Output signal analog absolute or PWM
  • Integrated MOLEX connector
Rotary Encoder Kit MxB22AH
Halleffect rotary encoder with analog signal, kit assembly series MAB22AH
Extremly robust kit sensor assembly for rough environment (IP67), with round cable
  • Electrical angle 360°
  • Protection class IP67
  • No wear parts (kit encoder)
  • Fine adjustment by a free rotatable mounting ring
  • Supply voltage 5 V, 9..30 V
  • Analog output: 0..5 V ratiometric, 0..10 V 4..20 mA, 0..20 mA
Rotary Encoder MAB22A
Halleffect rotary encoder with analog signal, servo flange series MAB22A
Compact rotary encoder with servo flange, precision ball bearing and round cable
  • Compact, robust with outstanding lifetime
  • Analog output: 0…10 V, 0…5 V ratiometric, 4…20 mA, 0…20 mA
  • Supply voltage: 5 V, 24 V, 9…30 V
Hall effect Rotary Encoder MP1627
Magnetic rotary encoder (Hall effect) MP1627
Rotary encoder with very wide operating temperature range in protection class IP65 in Ø27 mm housing with optional redundant electronics
  • Very large operating temperature range -40..125 °C
  • Flange- or bushing mounting
  • Optional redundant electronics
  • 5 V, 12 V or 24 V supply voltage
  • IP65
  • Sleeve bearing
Hall effect Rotary Encoder MP1618
Magnetic rotary encoder (Hall effect) MP1618
90° rotary encoder with low current consumption, low installation depth and mounting options in Ø22 mm housing
  • Wide operating temperature range -40…+105 °C
  • Also, available with redundant electronics
  • Less power consumption ≤ 7 mA (single), ≤ 14 mA (redundant
  • Bushing or flange mounting
  • Resolution nearly infinite
  • Effective electrical angle of rotation ±45° (=90°)
Hall effect Rotary Encoder MP1613
Magnetic rotary encoder (Hall effect) MP1613
Rugged miniature 90°-Hall-encoder with low current consumption in Ø13 mm metal housing e.g. as a thrust regulator in mobile applications
  • Wide operating temperature range -40..+105°C
  • Low power consumption ≤ 7 mA
  • Only Ø13 mm housing and sleeve bearing
  • Resolution nearly infinite
  • Effective electrical angle of rotation ±45° (=90°)
Hall effect Rotary Encoder MxB28
Incremental Hall-Effect Absolute Encoder Series MIB28
Encoder with incremental interface, ball bearings, high functionality and lifespan for modern device construction
  • Resolution up to 1024 ppr
  • 28 mm housing diameter
  • Supply voltage 5 V, 24 V (3,3 V on request)
  • Interfaces: Open Collector, TTL, Push-Pull for longer distances
  • Read out of the absolute position possible due to counting up (option EI3)
  • IP65 protection class
Hall effect Rotary Encoder MxB28
Hall-Effect Absolute Encoder MAB28
Encoder with different serial interfaces and ball bearings
  • Serial microcontroller interface (SER)
  • Serial peripheral interface (SPI)
  • Electrical angle 360°
  • Resolution: 12 bits or 14 bits
  • Supply voltage: 5 V
  • Ball bearings
Hall effect Rotary Encoder MxB28
Hall-Effect Absolute Encoder MAB28A
Rotary encoder with ball bearing and analogue output - can be equipped with 2 potential-free switches on individual positions
  • Electrical angle 360°
  • 12 bit resolution
  • Analogue output: 0…5 V, 0…10 V, 0…20 mA, 4…20 mA
  • 5 V PWM output
  • Redundant outputs
  • Supply voltage: 5 V, 8…30 V
  • Ball bearings
Rotary Encoder Hall-Effect-MxB36
Hall-Effect Absolute Encoder MAB36A
36 mm standard housing encoder with analogue output and ball bearings
  • Electrical angle 360°
  • 12 bit resolution
  • Analogue output: 0…10 V, 0…5 V ratiometric, 4…20 mA, 0…20 mA
  • Redundant outputs
  • Supply voltage: 5 V, 24 V, 9…30 V
  • The Highest lifespan due to ball bearings
Rotary Encoder Hall-Effect-MxB36
Incremental Hall-Effect Absolute Encoder MIB36
36 mm standard housing encoder with incremental interface and ball bearings
  • Resolution up to 1024 ppr
  • Supply voltage 5 V, 24 V
  • Interfaces: Open Collector, TTL, Push-Pull
  • Read out of the absolute position possible due to counting up (option EI3)
  • IP65 protection class
Hall effect Rotary Encoder MxB40
Hall-Effect Absolute Encoder MAB40A
Completely sealed encoder with analogue output and ball bearings
  • Electrical angle 360°
  • 12 bit resolution
  • IP67 protection class
  • Analogue output: 0…10 V, 0…5 V ratiometric, 4…20 mA, 0…20 mA
  • Redundant outputs
  • Supply voltage: 5 V, 24 V, 9…30 V
  • The Highest lifespan due to ball bearings
Hall effect Rotary Encoder MxB40
Incremental Hall-Effect Absolute Encoder Series MIB40
Completely sealed incremental encoder with ball bearings
  • Resolution up to 1024 ppr
  • Supply voltage 5 V, 24 V
  • Interfaces: Open Collector, TTL, Push-Pull for longer distances
  • Read out of the absolute position possible due to counting up (option EI3)
  • IP67 protection class
Magnetical Rotary Encoder HSM22S
Magnetic rotary encoder (Hall effect) HSM22S
Rotary encoder with wide operating temperature range in protection class IP65 in Ø22,5 mm housing with optional redundant electronics
  • Wide operating temperature range -40…105 °C
  • Also, available with redundant electronics
  • Only 13.1 mm housing depth
  • Compact Ø22.5 mm housing
  • 5 V, 12 V or 24 V supply voltage
  • IP65
  • Sleeve bearing
Optical Encoder SPE
Optical Encoder SPE
Space-saving optical encoder with up to 1000 ppr. and ball bearing for maximum durability in 22 mm housing
  • Compact design (Ø22 mm x 11 mm)
  • Up to 1000 pulses per revolution
  • Up to 15,000 rpm
  • With ball bearings for maximum lifespan
  • With sleeve bearing for applications as manual control
  • Simple installation with bushing thread
Optical Encoder MOM18
Optical Encoder MOM18
Space-saving optical encoder with ball bearing in 18 mm housing with high angular resolution up to 1600 ppr. and index
  • Up to 1600 ppr.
  • 2 channels and index
  • Ø18 mm housing, ball bearings
  • Open Collector or Line Driver
  • Protection class IP50
  • Radial or axial cable output
Optical Encoder SPEH Kit version
Optical Kit-Encoder SPEH
Very flat optical hollow shaft kit encoder with speeds up to 60.000 rpm and up to 1000 ppr.
  • Flat design 11 mm
  • Up to 60.000 rpm
  • Limit frequency 100 kHz
  • Up to 1000 pulses per revolution
  • Kit design
  • Option through-hole in cover
Optical Encoder SPM
Optical incremental encoder SPM
Reliable optical incremental encoders with increased (SPM) and reduced torque (SPNTM) with good adaptability to the application
  • Up to 1024 pulses / 360° (max. 5000 ppr)
  • 2 channels + index
  • TTL or line driver output
  • Shaft side up to IP55M / IP66S
  • Installation depth 18,7 mm
  • Option connector with lock
  • Made in Germany
Optical Encoder Kit SPTSM
Optical incremental encoder SPTSM as kit encoder
Reliable and easy-to-install optoelectronic kit encoder with long lifespan and adaptability to the application
  • Up to 1024 pulses / 360° (max. 5000 ppr)
  • 2 channels + index
  • TTL or line driver output
  • For shafts Ø4 mm to Ø8 mm
  • Installation depth 16.9 mm
  • Option assembly tools for safe installation
  • Option connector with lock
  • Made in Germany
Optical Encoder OP
Optical incremental encoder OP
Optical shaft encoder with very high resolution up to 10.000 ppr. and different operating torques
  • Up to 10.000 pulses per revolution
  • Only 12,6 mm housing depth
  • Sleeve bearing or ball bearing
  • 2 channels + index
  • Supply voltage 5 VDC
  • Output electronics TTL
Optical Encoder OPTS
Optical incremental encoder OPTS as kit encoder
High resolution kit encoder up to 10.000 ppr., quick and safe to install in the application
  • Up to 10.000 ppr.
  • 15.6 mm housing depth
  • Applicable for Øshaft 2...25 mm
  • 2 channels + index
  • Supply voltage 5 VDC
  • Output TTL
Optical Encoder PP
Optical incremental encoder PP
Optical shaft encoder with very high resolution up to 10.000 ppr. and plug connection
  • Up to 10.000 pulses per revolution
  • Only 16.51 mm housing depth
  • Sleeve bearing or ball bearing
  • 2 channels + index
  • Supply voltage 5 VDC
  • Output electronics TTL, line driver
  • Electrical connection plug with latch
Optical Encoder MHL40
Optoelectronic Hollow Shaft Rotary Encoder MHL40
Durable incremental hollow shaft rotary encoder with up to 5000 ppr. in Ø40 mm metal housing suitable for industrial use
  • Optical resolution 10 bis 5000 pulses per revolution
  • Metal housing, ball bearing
  • For 6, 8, 10, 12 mm shaft diameter
  • Output: NPN, open collector, linedriver, push pull
  • Optional with through hole
Panel Encoder-MRB
Optoelectronic Manual Encoder MRB
The MRB panel encoder has the widest selection of detent torques, push button operating forces and is suitable for low-power applications
  • Largest selection of detent torques and push button operating forces
  • Short push button travel path
  • Low power consumption <10 mA
  • Lifespan > 1 million revolutions
  • Resolution 25 or 16 ppr.
  • Up to IP55
  • TTL output with Schmitt trigger
Panel Encoder MRS
Optoelectronic Manual Encoder MRS
The MRS panel encoder with up to IP65 has the most compact housing and the largest selection of electrical connections
  • Very compact design
  • Various electrical connections
  • Up to IP65
  • Haptic feedback through 16, 24 or 32 clicks
  • Resolution 4, 6 or 8 ppr.
  • With or without push button / detent
  • Open Collector, 5 V / 3.3 VSUP
Panel Encoder MRT
Optoelectronic manual encoder MRT
The MRT panel encoder has the longest push button travel path and is suitable for low-power applications
  • Longest stroke with 1.2 mm for push button
  • Lifespan > 1 million revolutions
  • Low power consumption <10 mA
  • Resolution 25 ppr.
  • Up to IP54
  • 5 V power supply
  • TTL output with Schmitt trigger
Panel Encoder-MRX25
Optoelectronic Manual Encoder MRX25
The MRX25 panel encoder with detent, push button and optional IP65 proves its precision and quality even after many hundreds of thousands of operations
  • Combination with 25 ppr. and IP65 possible
  • Lifespan > 1 million revolutions
  • 5V or 3.3V power supply
  • Also, without button, without detent
  • TTL output with Schmitt trigger
Optical Encoder MOL40
Optoelectronic Rotary Encoder MOL40
Durable incremental rotary encoder with up to 5000 ppr. with ball-bearings in Ø40 mm metal housing suitable for industrial use
  • Optical resolution 10 to 5000 pulses per revolution
  • Metal housing, ball bearing
  • 6 or 8 mm shaft diameter
  • Output: NPN, Open Collector, Linedriver, Push Pull
Panel Encoder-MRX50
Optoelectronic Manual Encoder MRX50
The unrivalled panel encoders offer the combination of 50 pulses with detent and push button in protection class IP65
  • On the market unique combination of compact housing with 50 ppr., detent and push button
  • Lifespan > 1 million revolutions
  • Up to IP65
  • 5V or 3.3V power supply
  • TTL output with Schmitt trigger
Panel Encoder-MRL
Optoelectronic Manual Encoder MRL
Optoelectronic panel encoder with plastic shaft and 20 or 25 clicks / detents
  • Plastic shaft
  • Resolution 20 or 25 pulses per revolution
  • With or without detent
  • 5 V supply voltage
  • Numerous connection variants
Optical Encoder MOZ40
Optical incremental encoder MOZ40
High-quality incremental encoder in Ø39 mm metal housing with many output electronics variants and large selection of resolutions from 20..3600 ppr.
  • High-quality encoder with ball bearings
  • Large selection of resolutions 20..3600 ppr.
  • 2 channels + index
  • Operating voltage 5 V, 12 V, 24 V
  • Many output electronic variants
Optical Encoder M101
Optoelectronic Encoder M101
Incremental encoder with very high-performance price structure, very pleasant haptic and up to 128 ppr.
  • 2 channels / TTL output
  • Resolution 20…128 ppr
  • Compact design
  • Also, available with detent and switch
Optical Encoder MOL30
Optoelectronic Rotary Encoder MOL30
Industry-standard incremental rotary encoder with up to 3000 ppr. for high durability requirements
  • Optical resolution 10 to 3000 ppr
  • Metal housing, ball bearing
  • Output: NPN, Open Collector, Linedriver, Push Pull
Optical Encoder MOZ30
Optoelectronic Encoder MOZ30
High quality optical encoder in 28 mm housing, ball bearing, max. 1500 ppr and numerous electrical outputs
  • High-quality encoder in 28 mm metal housing
  • Ball bearing
  • 36...1500 pulses per revolution
  • 2 channels + index
  • Operating voltage 5 V, 12 V, 24 V
  • Output electronics: push-pull, voltage-output, open collector, line-driver
Optical Encoder MOT13
Miniature Optoelectronic Encoder MOT13
High resolution miniature rotary encoder in Ø13 mm housing and max. 16000 ppr. for robotics and compact applications
  • Ø13 mm housing
  • 100…16000 ppr
  • 2 channels and index
  • TTL, open collector or line driver output
  • Supply voltage 5 V
  • Ball bearings
  • Also, with hollow shaft
Optical Encoder MOT7
Miniature Optoelectronic Encoder MOT7
Incremental encoder in compact Ø7 mm housing and up to 400 ppr. resolution for use in miniaturized medical robots or in semiconductor manufacturing
  • Ø7 mm housing
  • Up to 400 ppr
  • 2 channels and index
  • Open collector output
  • Supply voltage 5 V
  • Ball bearings
Optical Encoder Miniature MOT6
Miniature incremental encoder MOT6
Incremental encoder in very compact Ø6 mm housing and high resolution with up to 1024 ppr. for use in miniaturized devices
  • Very compact housing with Ø6 mm
  • Easy connection to customer electronics
  • 1024 ppr. with 2 channels and reference pulse
  • Operating voltage 3.2 V, NPN voltage output
  • Durable thanks to ball bearing
Optical Encoder Miniature MOT5
Miniature incremental encoder MOT5
Incremental encoder in extremely compact Ø5 mm housing with up to 100 ppr. for use in miniaturized devices
  • Extremely compact housing with Ø5 mm
  • Easy connection to customer electronics
  • 64 (optional 100) ppr. with 2 channels and reference pulse
  • Operating voltage 3.2 V, NPN voltage output
  • Durable thanks to ball bearing
Hand wheel MHU
Optoelectronic Handwheel MHU
Robust Ø60 mm handwheel with 100 detent and very small installation depth is perfect for fast setpoint specification
  • High-quality Ø60 mm knob with 100 detents and crank
  • Small installation depth only 9.7 mm
  • Resolution 25 or 100 ppr.
  • Optionally in IP64
  • NPN or line driver output
  • Compatible with MELDAS and FANUC
  • Screw terminals as electrical connection
  • 5V power supply
Hand wheel MHO
Optoelectronic Handwheel MHO
Premium handwheel in Ø80 mm housing with outstanding haptics and 100 detents for very precise and tactile setpoint specification
  • Premium handwheel incl. knob Ø80 mm and crank
  • High quality massive construction
  • Operating ring / crank made of metal
  • Resolution 25 or 100 ppr., 100 detents
  • Degree of protection IP52
  • NPN transistor output
  • 5V power supply
  • Screw terminals
Optical Encoder MOE18
Optoelectronic encoder MOE18
Compact optoelectronic incremental encoder in Ø18 mm metal housing with up to 360 pulses per revolution
  • 2 x precision ball bearings for maximum lifespan
  • Max. 6000 rev./min
  • Compact design (Ø18 mm x 13 mm) in metal housing
  • Up to 360 pulses per revolution
Rotary Encoder Hall-Effect-MxB36
Hall-Effect Multiturn Absolute Encoder MAB36APM
Parametrizable multi-turn encoder with analogue output and ball bearings in standard Ø36 mm metal housing
  • Start and end points easily set in field via dry contacts
    10° to 200 x 360°
  • Ø36 mm housing with servo mount flange
  • 12 bit resolution
  • Analogue output: 0…5 V, 0…10 V, 4…20 mA
  • Supply voltage 8…30 V
  • Ball bearings
Hall effect Multiturn Rotary Encoder MxB40APM
Hall-Effect Multiturn Absolute Encoder MAB40APM
Completely sealed programmable multiturn encoder with analogue output and ball bearings
  • Start and end points easily set in field via dry contacts 10° to 200 x 360°
  • Ø40 mm housing with servo mount flange
  • 12 bit resolution
  • IP67 protection class
  • Analogue output: 0…5 V, 0…10 V, 4…20 mA
  • Supply voltage 8…30 V
  • Ball bearings
Guide for Rotary Encoders
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What is a rotary encoder?

Encoders detect or specify angular positions/positions and convert this information into electrical signals. They are angle sensors that transmit their measured value to an electronic system without contact. And it is precisely this characteristic that distinguishes them from potentiometers, which are passive components. Basically, each encoder consists of a housing, an electronics with sensor as the heart of the measurement and the electrical connection. Depending on the version, a shaft with a shaft bearing is also part of the sensor in order to realize the angle measurement mechanically. There are numerous related terms for the word encoder. However, if the angle is provided as a complete value (i.e. as an absolute value) with a fixed reference to a zero position, then the rotary encoder is referred to as an absolute encoder. If only the change in angle is provided, i.e. the output signal only provides relative information, then the encoder is an incremental encoder. In this guide only contactless technologies with magnetic or optical measuring principle are described.


What does "contactless" mean?

Contactless means that the measured value is transmitted to the electronics without contact. For example, a rotating part of the application is connected to the encoder's shaft, and the measured value is recorded by the electronics. However, there is no direct mechanical connection between the two components. Thus, the measured value is therefore transmitted without contact.
All contactless encoders from MEGATRON are based either on magnetism or on an optical measuring principle. With magnetic encoders there is practically no wear on the acquisition (electronics) and with optical encoders only the optical detection unit has a limited lifespan. The only noteworthy wear occurs in contactless encoders via its mechanical components for recording measured values when there is a shaft and shaft bearing.


Magnetic rotary encoder with Hall effect

The Hall effect, named after Edwin Hall, describes the occurrence of an electrical voltage, the so-called Hall voltage, in a current-carrying conductor (Hall element) that is located in a stationary magnetic field. If you place a circular diametrically magnetized (north pole / south pole) permanent magnet over a Hall element, expose this magnet to a rotary movement and measure the voltage at the output of the amplifier circuit, then a sinusoidal output voltage curve is measured.

In principle, external magnetic fields can interfere with this technology. So-called gradient-based Hall sensors are mainly used, which are largely insensitive to these disturbances.
For more details, see our guide on the topic of "absolute encoders".

For further details see our guide to absolute encoders.

Advantages of magnetic encodersDisadvantages of magnetic encoders
 
  • The best choice when durability is required
  • Less sensitive to vibrations
  • Less sensitive to changing environmental influences, such as temperature fluctuations, high relative humidity
  • High actuation speeds (rpm) possible
  • Suitable for operation in oily, dirty environments (machine halls, construction sites, etc.)
 
 
  • External magnetic fields can disturb the measurement or lead to measurement failure
  • Magnetic encoders have a relatively high signal jitter. This can be disadvantageous if positions are to be determined repeatedly as exactly as possible (e.g. positioning of a plotter).
 

Optical encoders

Optical encoders are based on a contactless, optical scanning principle. Light is generated by a light-emitting diode that shines through a coding wheel onto a photodetector. The photodetector generates an electrical signal that is processed by the electronics and used to output the measured value.
In non-contact rotary encoders with optical scanning systems, the light-emitting diodes are subject to a continuous ageing process during operation. In addition, dust on the optical system  contribute to the ageing of the sensor.

For more details, see our guide to incremental encoders.

Coding wheel

The overview of all incremental encoders with optical sensor technology can be found here

Advantages of optical encodersDisadvantages of optical encoders
 
  • Angle encoders with a high optical resolution enable position measurement with very high accuracy
  • High repeatability of the measurement result
  • Very high actuating speeds possible
  • Very stable against external magnetic fields (immission)
  • Excellent suitability for exact speed determination
  • Very long lifetime
  • Low signal jitter
 
 
  • The optical system is subject to a continuous ageing process
  • Sensitive to vibrations
  • Sensitive to high temperature fluctuations and high relative humidity
  • Environments in which short-wave radiation of higher intensity occurs, such as gamma radiation, can irreversibly damage the optical system (for example, interaction with coding wheels made of Mylar)
 

Incremental encoders

Incremental encoders output a certain number of rectangular signals instead of information proportional to the angle (cf. absolute encoders). They are also referred to as pulses. Incremental encoders are therefore also called rotary pulse encoders and the number of pulses per revolution is always given (unit imp./rev.). One pulse corresponds to one period duration. The term "one increment" is also used for a period duration. This also explains the term incremental encoder. An external evaluation unit is always required to evaluate the measurement result of an incremental encoder, for example a counter.

Signal sequence incremental encoder

The following points are to be observed in particular:

  • For an angle measurement the number of pulses must be counted in an external evaluation unit and the sum of the pulses must be converted into an angle.
  • If the operating voltage of the counter is interrupted, the counter information is usually lost. If then the absolute value of the angle relative to a reference point is to be measured or calculated, referencing must be carried out by passing through the zero position.
  • For a speed measurement the number of pulses per time is calculated.

Incremental encoders are available with different numbers of pulses per revolution. If, for example, there are 360 pulses/rev, this means that 360 pulses (360 signal periods) are output per full shaft revolution (360°). If, for example, 1024 pulses/revolution are specified, this means that 1024 pulses (1024 signal periods) are output per full shaft revolution (360°).
Incremental encoders are available from MEGATRON as Hall encoders and as optical encoders. For a detailed description, see the Incremental Encoder Guide.


Absolute encoders

Absolute encoders output an analog or digital signal proportional to the angle. There is therefore a fixed reference point for the angle measurement. Rotary encoders with analog output provide the measured angle as output voltage, output current or pulse width (PWM). Digital interfaces for the output of absolute values are available in the form of communication protocols.
For a detailed description, see the Absolute Encoder Guide.

Analog output signal of a singleturn absolute encoder

Measured angle [°, degrees]Output voltage [Volt]
0 V
360°10 V
45°1.25 V
90°2.5 V
180°5 V
360°10V

The table shows the output voltage curve at different measurement angles using the example of a 0...10 V voltage output


Singleturn encoders

Singleturn encoders are absolute encoders that can only measure the angle of one full revolution. After one full revolution, the output signal shows the same value every 360° as for 0°. Most contactless singleturn absolute encoders measure the full angle range from 0° to a maximum of 360°. Only a few products measure angles in a limited angular range, for example +/- 45°.


Multiturn encoders

True-Power-On absolute encoder HSM22M

Compared to single-turn encoders, multiturn encoders are able to measure angles beyond 360° The measuring system is able to count the number of revolutions and it is usually programmed so that the signal rises continuously over the maximum electrically effective angular range. For example, certain multiturn absolute encoders from MEGATRON are able to measure angles up to a maximum of 72000°(up to 200 shaft revolutions). The overview of all multiturn encoders can be found here.
Without special precautions, such encoders lose their position information if the supply voltage is interrupted. One class of multiturn encoders are true power-on encoders. Such an encoder also delivers a correct output signal if the angle of rotation changes as desired during a temporary absence of voltage.


Actual value device and setpoint device

The two terms "actual value device" and "setpoint device" are defined by their purpose in the application. Some encoder models can be used for both purposes.
For a setpoint device, a value is set manually. A setpoint is specified via a manual rotation of the encoder shaft (usually via an adjustment button mounted on the shaft). These adjusters / manual adjusters are used in control panels, for example to navigate through menus or to specify various parameters for measuring devices. The overview of devices for manual input can be found here.
The actual value encoder is used as a synonym for an angle sensor or rotary encoder if an angle is simply measured and is not specified manually by hand. Since this does not necessarily correspond to the target value in an application, the two terms are used to differentiate. Setpoint and actual value transmitters can be parts of control loops.

MRX50 rotary encoder as setpoint devices


Angular properties and direction of rotation

Information on electrical and mechanical angle of rotation and direction of rotation of the ETAM25 series

Mechanical angle of rotation

The mechanical angle of rotation is the entire angle at which the encoder can be operated mechanically. The mechanical angle of rotation is not mechanically limited for most contactless encoders, i.e. the shaft of the encoder can be operated clockwise and counterclockwise continuously without stopping the rotary motion. With a few exceptions, there is the option of mechanical end stops. These are particularly useful for setpoint devices (manual adjusters). One example is the ETAM25 series from MEGATRON which has mechanical end stops.


Electrically effective angle of rotation

The electrically effective angle of rotation is the angular range in which the output signal changes. The following illustrations show exemplary signal output functions of singleturn absolute encoders. In both cases the mechanical angle of rotation is 360°.

Example 1

Example 2


  • In the first example, the encoder signal changes over the entire angular range of 0...360°. The range shown in orange is the electrically effective angle of rotation.
  • In the second example, by programming the output signal differently, there are two different areas where a signal change occurs: Here the electrically effective angle of rotation is in the range between 0°...90° and between 180°...270°.

Direction of rotation

The direction of rotation describes the change in output signal in relation to the direction of rotation of the shaft. The direction of rotation of the shaft is specified when the encoder is viewed from the front. That is, when the observer looks at the shaft end and the. With a kit encoder (without its own shaft), the observation is made on the side of the housing facing the magnet.
A distinction is made between clockwise and counter-clockwise. For the description, the abbreviations CW for clockwise and CCW for counterclockwise have become established. The adjacent graphics illustrate the difference in the signal curve using the example of a single-turn absolute encoder. The direction of rotation CW or CCW can be selected for almost all absolute encoders by the customer when configuring the encoder.


Resolution and update rate

Digitally operating devices process the measurement signals with a certain resolution. For absolute encoders with digital signal processing, two parameters are relevant, which can also be found in the encoder data sheet:
The resolution (in bit)

  • The higher the resolution of a digitally operating sensor, the finer analog signals can be processed. Analog output curves of digital devices therefore always have a fine step (staircase formation). The height of those steps is determined by the resolution of the sensor.

The update rate (in microseconds [µs] or milliseconds [ms])

  • Signals from digitally working sensors are always transmitted with a certain time delay.

If this information can be found in a data sheet of an encoder, this is an indication that it processes data digitally. A detailed description of the meaning of these values and sample calculations can be found in the absolute value guide.


Protection against environmental influences / IP protection

IP stands for Ingress Protection. The IP grade specifies what measures are in place to protect shaft bearings, housings and the electrical connections against penetrating solids and fresh water of a product. One speaks formally correctly of the IP protection class of a product.
The consideration for the protection of liquids only refers to fresh water. All other media such as oils, salt water, suspensions, alkalis or acids are excluded from consideration.
The IP specification consists of two digits, which is followed by the two letters "IP":

  • First digit: Protection against penetrating particles
  • Second digit: Protection against ingress of fresh water

Fully sealed ENA22K Hall kit encoder: Caution, the magnet is exposed. The sealing is only valid for electronics and housing.

Distinction shaft side IP protection, rear side IP protection, IP protection of the electrical connection

For contactless angle encoders, in addition to the total value for the product, a distinction is made between shaft-side IP protection, rear-side IP protection and IP protection of the electrical connection. However, in the case of an electrical connection cable with tinned cable ends, the cable ends are excluded from the IP protection consideration.

IP protection observed with one shaft in motion and at standstill

For angle encoders with their own shaft bearing, a distinction is often made between the protection class for the shaft in motion and the shaft at standstill. In these cases, the information is defined by the letters "M" for movement (shaft in motion) or "S" stop (shaft at standstill) following the IP protection numbers.
A higher shaft-side IP protection for a stopped shaft can be relevant if the encoder is part of an application/plant which is only cleaned during a (plant) standstill.


Electrical connections

Supply voltage

All contactless angle encoders require a direct voltage (DC) as supply voltage (VSUP) for operation. A distinction is made between rotary encoders that have a supply voltage change within a defined range if

  • there is a ratiometric relationship to the output signal
  • no ratiometric relationship exists, i.e. has no influence on the output signal

With a ratiometric relationship between supply voltage and output signal, the output signal changes in the same multiplicative ratio as the supply voltage. This option is only available for absolute encoders with analogue signal output.  
Furthermore, not all available supply voltage ranges can be combined with every output electronics. When selecting the supply voltage, it should therefore be checked whether the desired output circuitry is available for the desired supply voltage. The data sheet of the angle encoder provides information about the possible combinations.


Redundancy

Some applications require redundancy of the sensor signal. The following objectives are often the reason for using redundant encoders:

Increasing the availability of systems

  • The double design of the sensor reduces the probability of system failure. If one of the two lines fails, an error is logged. However, the machine or plant can continue to run until the next maintenance interval, where the sensor is replaced without loss of machine time.

Increase of the operational safety

  • When operating safety-critical machines (e.g. vehicles, aviation, etc.), a failure can be fatal. The redundancy enables a safe, controlled shutdown of these machines or systems until the sensor is replaced. Redundancy is mandatory for many applications of this type.

If it is not possible to install two encoders in principle, it is possible to implement encoders with two separate supply voltages and separate ground (GND) for the operation of the encoder, which provides an electrically isolated, additional electronics.

  • With magnetic angle encoders the magnet is always installed at the end of the shaft. Therefore, it is not possible here to lead the shaft through the housing to another sensor. The magnetic sensor element itself is double/redundant and for some models galvanically separated as an option.
  • With optical angle encoders it is possible to realize tandem versions, which mechanically only have the shaft in common, but are otherwise completely doubled.

Signal outputs

The following signal outputs are available for contactless absolute encoders.

Analogue:

  • Voltage output (different ranges, ratiometric, non-ratiometric)
  • Current (0...20 mA, 4...20mA,...)
  • Pulse width modulation (PWM)

Digital:

  • SPI
  • SER
  • SSI

 

The following output circuits are available for contactless incremental encoders:

  • OC (Open Collector, Pull Up resistor not integrated in encoder)
  • Voltage Output (Open Collector circuit incl. pull-up resistors integrated in the encoder housing)
  • TTL (Transistor Transistor Logic)
  • PP (Push Pull)
  • Linedriver

Cabling

Cable lengths and cable tolerances
For electrical connection cables (tolerances) of angle encoders, other guidelines apply than for encoder housings and shafts. Note: If the line tolerances are not explicitly mentioned in the data sheet, the IPC / WHMA-A-620 applies:

Cable lengthPermissible tolerance of the connection cable (incl. plug)
≤0.3 m+25 mm -0 mm
>0.3 m...1.5 m+50 mm -0 mm
>1.3 m...3 m+100 mm -0 mm
>3 m...7.5 m+150 mm -0 mm
>7.5 m+5% -0%

Cable Shield
For MEGATRON angle encoders with metal housing, the connection cable is shielded by an external cable shield. With all angle encoders in plastic housing, the connection cable is not shielded.


Designs of rotary encoders

Encoders are offered in a wide variety of housing designs. They can be divided into kit encoders (without shaft bearing), and encoders with shaft bearing. In the latter case, a distinction is made between versions with plain bearing or ball bearing, and solid or hollow shaft.

Kit-Encoder

MAB12AH series magnetic kit encoder

Kit encoders have no shaft and therefore no shaft bearing. For these encoders the term "encoder with external shaft bearing" is also used because the bearing is not part of the encoder. With magnetic encoders a magnet is fixed to the end of the shaft, with optical kit encoders the encoder disc is fixed to the shaft in the application. Kit encoders are suitable for highest speeds up to many thousands of rpm and are practically not subject to mechanical wear.
Due to the lack of mechanical connection between the magnet and the encoder, the following decouplings can be realized:

  • Mechanical decoupling
  • Galvanic decoupling (no electrical potential reference between shaft and encoder)
  • Thermal decoupling

Encoders with bearing - "shaft encoder" and "hollow shaft encoder"

These encoder types have their own shaft bearing. A distinction is also made between two designs: Encoders with solid shaft (then often just called "shaft") and encoders with hollow shaft. 
The versions with solid shaft are also called shaft encoders. For shaft encoders, the term "angle encoder with integral bearing shaft" is also used. 
Hollow shaft encoders on the other hand, as the name suggests, do not have a solid shaft. An application-side shaft is inserted into the hollow shaft and attached to it. For versions with through holes, it is even possible to push the shaft completely through the encoder, which can then be freely positioned axially.


Installation and mounting

The possibilities of mechanical mounting of the encoder in the application depend on the design of the encoder housing. MEGATRON offers a total of five different mounting options for its contactless encoder families. The mounting can be done by means of

  • Bushing
  • Flange
  • Threaded holes
  • Synchro flange
  • Mounting ring
  • Spring plate

Central thread and union nut (bushing)

The version with central thread is a very easy and quick fastening method. For mounting an encoder with bushings, generally only one single hole has to be drilled in the mounting plate of the application. The bearing bush of the encoder is guided through this hole until the face of the encoder housing or the surface of the centering collar rests on the mounting plate. Finally, the encoder is fastened to the mounting plate by means of a union nut and shim/locking washer. The union nut and washer are often included in the scope of delivery.
Some encoder families also have an anti-rotation pin. This prevents unintentional rotation of the encoder housing around the center axis during fastening of the union nut. An additional second hole for this anti-rotation pin must be drilled in the mounting plate. In addition, the anti-rotation pin (if present) fulfills the function of a zero point reference (0° position).
To fix the encoder in a mounting plate, the hole breaks through the mounting plate completely. This can facilitate the penetration of liquids and dust from the front to the back of the mounting plate. To prevent this, an additional sealing element is optionally included in the scope of delivery, which is inserted between the front of the encoder and the mounting plate. This sealing element is an option for the ETx25 encoder family, for example.

Absolute encoder series ETA25 with central thread (bushing)


Flange mounting

Flange mounting is a widely used, simple mounting method that prevents the encoder housing from twisting around the centre axis during mounting. To fasten the sensor, three holes must be drilled in a mounting plate in the application. One hole is required for the centering collar or the central thread and two more are needed for fastening the encoder by means of screws. The screws for fastening are usually not included in the scope of delivery.


Mounting with threaded holes

Fastening by means of threaded holes is a very safe method and is based on commercially available standard parts. To fasten such encoders, at least three holes must be drilled in a mounting plate in the application: One hole for the centering collar and two additional holes for mounting the encoder. A threaded hole in the encoder housing serves as a zero reference (0° reference). The screws for fastening are usually not included in the scope of delivery.


Servo flange

This mounting method allows the zero point (reference point) to be changed subsequently by rotating the encoder housing and is therefore particularly useful for absolute encoders. At least four holes must be drilled in a mounting plate for mounting.

  • One hole for the centering collar, which completely penetrates the mounting plate and
  • three additional holes on the back of the mounting plate for screwing the clamps, which do not have to penetrate the mounting plate.

The synchro clamps are not part of the scope of delivery and can be ordered from MEGATRON as accessories. By means of the terminals the encoder is fixed by the contact pressure against the mounting plate. The fourth threaded hole in the encoder housing serves as a zero point reference (0° reference).


Mounting by means of a mounting ring

This mounting method is limited exclusively to encoders without shaft bearing (kit encoder). For mounting, at least three holes must be drilled in a mounting plate: One hole for the centering collar, which completely penetrates the mounting plate, and at least two additional holes on the back of the mounting plate for fixing the mounting ring, which do not have to penetrate the mounting plate. If the encoder is initially loosely attached with the mounting ring, this allows the encoder to be rotated around the centre axis to align the zero point (i.e. especially useful for absolute encoders). The position is then fixed simply by tightening the screws.

MxB22 series kit encoder with mounting ring


Spring plate assembly

MHL40 series encoder with spring plate assembly

This mounting method is only used for hollow shaft encoders. The advantage of this method is that mechanical influences on the encoder caused by radial and axial eccentricities of the application-side shaft can be minimized, which reduces the load on the bearing. This mounting method requires at least 2 holes for mounting the encoder.


Product customization

For over 60 years MEGATRON has been a reliable partner for your design-in. In addition to the various options of our sensors, we also offer specific designs starting from small quantities, which are exactly tailored to your application requirements. Whether it is a project in the early phase or a series production - we will be pleased to accompany and support you.

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