Panel Mount Encoders                       © 2012 CUI Inc
IntroductionPurposeThe purpose of this training module is to familiarize you with the principles of panelmount rotary enco...
What Are Encoders? Encoders are a type of sensor designed to  provide rotation information An encoder sends out a pulse ...
What are panel mount encoders? Panel mount encoders are designed for use in human interface applications They provide an...
Why an Encoder?DIGITAL   Encoders:           Consistent           Accurate           Digital  vsANALOG    Potentiometer...
ApplicationsPanel mount encoders, like the ACZ and C14 series, are ideal forapplications in many industries Defense & Aero...
Applications                             continuedResearch & Science                                   Industrial Automati...
Important SpecificationsPPR(pulses per revolution)The number of square wave pulses per revolution of the encoder shaft per...
PulsesPulse = One full square wave cycle. A transition from low to high to low.                                       1 fu...
Output Square wave output over two channels The signals are identical except they are slightly offset By detecting whic...
Output          Continued                                       Quadrature Truth TableMicrocontrollers use different      ...
Sinking and Sourcing Sinks provide paths to ground Sources provide paths to a voltage A sink needs a source to work and...
Mechanical vs. Optical TechnologyMechanical          Optical Inexpensive        Cleaner Output Rugged             Long...
How Optical Encoders Work Attached to the shaft, inside the encoder body  is a wheel a with slits cut in at regular inter...
C14 Optical Encoder SeriesAvailable options                    Features 16 & 32 PPR (64 & 128 CPR)          Compact – 15...
How Mechanical Encoders Work A code wheel with contacts turns inside the  unit as the encoder shaft is turned When conta...
Switch Bounce and Debounce in Mechanical Encoders An ideal switch will have two states, on and off, and it will instantly...
ACZ Mechanical Encoder SeriesAvailable options 12, 15, 20 ,30 PPR Push switch or no switch Detents or no detents 15, 2...
Summary CUI’s ACZ and C14 series encoders are designed to provide an accurate  and inexpensive method for user input acro...
www.cui.com              © 2012 CUI Inc
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Panel Mount Encoders

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Explains how panel mount rotary encoders work and the differences between mechanical and optical encoder technologies. Also covers CUI's ACZ and C14 series encoders and typical applications for these.

For more information on the ACZ series visit:
http://www.cui.com/ACZ_Panel_Mount_Encoders

For more information on the C14 series visit:
http://www.cui.com/C14_Panel_Mount_Optical_Encoders

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  • There are many types of encoders. In this training module we will focus on rotary encoders. Rotary encoders can be defined as transducers designed to turn a rotational displacement into an electrical signal which can be read by a microprocessor.
  • Panel mount encoders are a type of rotary encoder. They are primarily used for human interface purposes, i.e., a volume knob on a stereo. They give the user the ability to control various system parameters by providing the link between the user and the system processor.
  • Panel mount rotary encoders are rapidly gaining popularity over potentiometers which are the other, major panel mount components used to translate rotational movement into a readable signal. The first advantage that encoders offer over potentiometers is consistency. Potentiometer manufacturing tolerances are large, leading to inconsistencies between units in the same batch. Accuracy is tied to consistency. Secondly, digital outputs are more compatible with today’s digital devices and require no analog to digital converters, reducing cost and preventing errors.
  • Panel mount encoders are used in many applications across numerous industries, including defense & aerospace, medical, consumer goods, and test & measurement. The following two slides highlight some common applications.
  • PPR (pulsesper revolution) determines the encoder’s resolution, which is defined as the number of square wave pulses per 360 degree rotation of the encoder. Additionally, we define PPR as the number of low to high transitions per channel per revolution. Occasionally, an encoder’s resolution is specified as CPR (counts per revolution), which is simply the number of quadrature state changes per revolution, CPR= 4 X PPR. Detents are useful in providing feedback to the user by “clicking” into place as the shaft is rotated. Detents are specified as the number of clicks per 360 degree rotation. The push switch feature simply provides another user input signal. It is often used to select the function to be manipulated by turning the encoder knob.
  • CUI’s rotary encoders output a square wave signal. The signal is comprised of a series of pulses, which are defined as one full square wave cycle, or a transition from low to high back to low, or high to low back to high. Simply stated, a pulse is a measure of the waveform from one identical point to the next.
  • CUI’s rotary encoders utilize square waves with two channels that are offset 90 electrical degrees from each other. By detecting which channel is leading the other, direction can be monitored.
  • Most applications will use quadrature state changes to increase the counts per revolution. Increasing the counts per revolution increases the effective resolution of the encoder. In this case, one cycle is a transition from low to high back to low on both channels.
  • Most panel mount encoders need to be connected to a microcontroller that can source current. The microcontroller provides a path to V+ and the encoder provides a path to ground creating a complete circuit. Another term commonly used for sinks is “open collector.” This means the collector of the output transistor is external to the unit.
  • Mechanical encoders are less expensive and can handle a wider range of voltages. However, they require de-bounce circuitry to produce a clean signal and have a shorter cycle life. Optical encoders, on the other hand, are typically more expensive but have a higher cycle life and provide a cleaner output signal that does not require de-bounce circuitry. Additionally, for precision applications, optical encoders can provide higher resolutions.
  • Optical encoders are made up of three basic parts: a light source, a light detector, and a code wheel. The source shines light through slits in the code wheel and the detector senses this light. The code wheel has evenly spaced slits which transmit and alternately block the light source. Internal circuitry enables and disables an output depending on whether or not the light is being detected or blocked.
  • The C14 optical encoder series holds some advantages when compared to other optical encoders on the market. It is compact, measuring 15 mm across. The body and shaft feature metal construction, creating a rugged package that can be further protected with the optional IP65 rating. The C14 outputs a crisp, clean square wave, making interpolation easier and more accurate for the microprocessor. Finally, with a rotational and push button life of 1 million cycles, the C14 is built to last.The series is available in 30 configurations. Some of the key options include 16 and 32 pulses per revolution, configurations with and without push button, with and without detent, multiple shaft styles, and three different mounting orientations.
  • Mechanical encoders are essentially series of switches. The code wheel contains contacts spaced evenly along its outer edge. Another contact is stationary and mounted on the encoder chassis. As the code wheel turns it makes, then breaks, contact with the code wheel contacts, one at a time.  This making and breaking of a circuit generates a voltage pulse which can be read by a microcontroller.
  • In a perfect world, a switch is characterized by having two states, on and off. Unfortunately, in the real world, switches can hover or bounce between the two states, creating a distorted signal. Switch bounce can be incorrectly read as additional pulses by a microcontroller. To prevent this debounce, circuitry is used to “square up” the output. Because mechanical encoders are essentially a series of mechanical switches, they require debounce circuitry and programming to ensure that the output can be used.
  • The ACZ mechanical encoder series is available in 40+ configurations. Some of the key options include various resolutions, configurations with and without push button, with and without detent, multiple shaft styles, and two different PCB mounting orientations.
  • Panel Mount Encoders

    1. 1. Panel Mount Encoders © 2012 CUI Inc
    2. 2. IntroductionPurposeThe purpose of this training module is to familiarize you with the principles of panelmount rotary encoders and the key features of the ACZ and C14 series availablethrough Digi-Key.Objectives To explain how panel mount rotary encoders fundamentally work and provid definitions to key specification and principles Describe the difference between mechanical and optical encoder technology Describe the key features of CUI’s ACZ and C14 series Detail typical applications these encoder are used in Content: 19 pages Learning Time: 15 minutes © 2012 CUI Inc
    3. 3. What Are Encoders? Encoders are a type of sensor designed to provide rotation information An encoder sends out a pulse each time it is moved a certain number of degrees A microprocessor counts these pulses and calculates rotation © 2012 CUI Inc
    4. 4. What are panel mount encoders? Panel mount encoders are designed for use in human interface applications They provide an accurate and inexpensive method for user manipulation of electronic products © 2012 CUI Inc
    5. 5. Why an Encoder?DIGITAL Encoders:  Consistent  Accurate  Digital vsANALOG Potentiometers:  Inconsistent  Accuracy is hardware dependent  Analog © 2012 CUI Inc
    6. 6. ApplicationsPanel mount encoders, like the ACZ and C14 series, are ideal forapplications in many industries Defense & Aerospace Rescue & Security  Simulators, cockpit control  CCTV (closed circuit TV)  Handheld, mobile, fixed radios  Handheld, mobile, fixed radios  Ground control, weapon control  Rescue tools and equipment  Marine applications Light & Sound Infrastructure Control  Studio mixers and cutting  Traffic control for car, railway  PA and on-stage equipment  Traffic information systems  On-site transmission equipment  Power plant and energy distribution  Communication network control © 2012 CUI Inc
    7. 7. Applications continuedResearch & Science Industrial Automation Electronic lab and instrumentation  Motor drives Meteorology and geology measures  PLCs and control systems Petro and pharmaceutical measures  Remote control units Other physical measures  Tooling machinesTransportation Vehicle Building & Facilities Construction machinery cockpits  Heater and air conditioning Remote control for construction  Lock and access systems Rail car and ship cockpits  Remote control units Car side passenger information  Illumination controlConsumer Medical Audio equipment/home entertainment  Surgery tools White goods (Washer/Dryer)  Analysis devices Espresso machine  X-ray, ultrasonic and MRI Fitness and wellness equipment  Life recovery and sustainment © 2012 CUI Inc
    8. 8. Important SpecificationsPPR(pulses per revolution)The number of square wave pulses per revolution of the encoder shaft per channel,this measure is also known as “resolution”CPR (counts per revolution)The number of quadrature state changes per revolution, or PPR x 4DetentsThese prevent unwanted rotation and provide a “click” every time the shaft isrotated a certain number of degreesPush SwitchThe encoder shaft can be pressed down to actuate a simple SPST switch © 2012 CUI Inc
    9. 9. PulsesPulse = One full square wave cycle. A transition from low to high to low. 1 full cycle © 2012 CUI Inc
    10. 10. Output Square wave output over two channels The signals are identical except they are slightly offset By detecting which signal is leading, the direction of rotation can be monitored Clockwise Rotation Counter-Clockwise Rotation © 2012 CUI Inc
    11. 11. Output Continued Quadrature Truth TableMicrocontrollers use different Statemethods for counting Position A B 1 0 0 Pulses on one channel 2 1 0 1 count per pulse 3 1 1 4 0 1 Pulses on two channels 1 0 0 Using both channels doubles the 2 1 0 number of counts 3 1 1 4 0 1 Quadrature state changes 1 0 0 4 counts per cycle 2 1 0 3 1 1 4 0 1 © 2012 CUI Inc
    12. 12. Sinking and Sourcing Sinks provide paths to ground Sources provide paths to a voltage A sink needs a source to work and vice versa A faucet needs a sink, and a sink needs a faucet CUI Inc panel mount encoders sink current, requiring a source to work properly © 2012 CUI Inc
    13. 13. Mechanical vs. Optical TechnologyMechanical Optical Inexpensive  Cleaner Output Rugged  Longer lasting Variable source  Less external circuitry voltage levels  Higher resolution © 2012 CUI Inc
    14. 14. How Optical Encoders Work Attached to the shaft, inside the encoder body is a wheel a with slits cut in at regular intervals A beam of light is aimed across the code wheel A detector on the other side is used to tell if the beam is being transmitted through a slit or blocked by the material between slits As the shaft is turned, the light beam is alternately blocked (state=0) or transmitted (state=1) © 2012 CUI Inc
    15. 15. C14 Optical Encoder SeriesAvailable options Features 16 & 32 PPR (64 & 128 CPR)  Compact – 15 mm width  Rugged – Metal body construction Push switch or no switch and optional IP65 rating Detents or no detents  Quadrature output 6 different termination types  Clean square wave output 3.175, 6, 6.35 mm shaft diameter  Life – 1,000,000 cycles 5 different mounting types Optional IP65 rating © 2012 CUI Inc
    16. 16. How Mechanical Encoders Work A code wheel with contacts turns inside the unit as the encoder shaft is turned When contact is made the voltage at the output is pulled up When contact is broken the output is pulled low Moving contact Stationary contact © 2012 CUI Inc
    17. 17. Switch Bounce and Debounce in Mechanical Encoders An ideal switch will have two states, on and off, and it will instantly move to one of these positions In the real world a switch will hover, or bounce, between these states during switching operations To compensate for this effect, switches need “debounce” circuitry and/or programming Real world Ideal Bounce © 2012 CUI Inc
    18. 18. ACZ Mechanical Encoder SeriesAvailable options 12, 15, 20 ,30 PPR Push switch or no switch Detents or no detents 15, 20, 25 mm shaft length Horizontal or vertical mounting © 2012 CUI Inc
    19. 19. Summary CUI’s ACZ and C14 series encoders are designed to provide an accurate and inexpensive method for user input across a wide range of applications The ACZ series utilizes mechanical encoder technology, offering a rugged, low cost solution The C14 series utilizes optical encoder technology, offering a clean signal and long cycle life for high precision applicationsLearn More View CUI’s panel mount encoders View CUI’s full Encoder product portfolio © 2012 CUI Inc
    20. 20. www.cui.com © 2012 CUI Inc
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