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Encoder

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Absolute Encoder - provides the shaft position in a bit configuration and is able to maintain or provide absolute position even after instances of power loss/failure. Accuracy – difference in distance between the theoretical and the actual position. Cycles Per Revolution (CPR) - Cycles per revolution are the number of output pulses per complete revolution of the encoder disk Encoder - is a sensor of mechanical motion that generates digital signals in response to motion. Inc
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  Absolute Encoder   - provides the shaft position in a bit configuration and is able to maintain or provide absolute position even after instances of power loss/failure. Accuracy    –  difference in distance between the theoretical and the actual position. Cycles Per Revolution (CPR)  - Cycles per revolution are the number of output pulses per complete revolution of the encoder disk Encoder   - is a sensor of mechanical motion that generates digital signals in response to motion. Incremental Encoder   - device that provides a train of pulses due in response to mechanical motion. The output of this encoder is in form of a squarewave. Index  - a separate output channel which provides a single pulse per shaft revolution. It can be used to establish a reference or marker for a starting position. Interpolation  - is the method of increasing the resolution of an encoder. This method allows for the encoder to produce a higher resolution output without increasing the overall size of the disk and encoder. Line Driver   - is a sourcing ou tput. This means that when in ‘ON’ state the line driver will supply Vcc and in the ‘OFF’ state the driver will float. A sinking input is required for line driver applications. Open Collector   - is a sinking output. In the ‘OFF’ state, an open collector w ill be grounded and in the ‘ON’ state, the open collector will float. A sourcing input is required for open collector applications. Pulses Per Revolution (PPR)  - the total number of pulses produced per full revolution of the encoder shaft. Push-pull  - is a combination between a line driver and an open collector. In the ‘OFF’ state it will be grounded and in the on ‘ON’ state it will supply Vcc.   Quadrature Encoder   - two output channels which are out of phase by 90 electrical degrees. From the phase difference, the direction of rotation can also be determined.    Resolution    –  number of line increments on a disk. Resolution for incremental encoders is often referred to as cycles per resolution and for absolute encoders it is in terms of bits. Single Channel Encoder     –  has only one output channel and is used in speed applications. Squarewave  - a repetitive waveform corresponding to high and low signals. Encoder Quiz  1. What are single output channel incremental encoders used for?  A. Sense Direction B. Sense Speed (Tachometers)  C. Position Feedback 2. Which of the following is a NOT difference between absolute and an incremental encoder?  A. Absolute encoders provide a unique position. B. Absolute utilize concentric circles on a transparent disc while incremental encoders utilize evenly spaced opaque sections to determine movement. C. Both absolute encoders and incremental encoders lose position due to power loss/failure.  3. Which of the following applies to an Index Channel?  A. Position Tracker B. Reference/ Homing Point C. Determining Distance D. All of the Above  4. What does an Encoder do?  A. Senses mechanical motion. B. Provides information concerning position, velocity and direction. C. Converts analog into digital information. D. None of the above. E. All of the above.    5. What does CPR stand for?  A. Cycles per Revolution B. Counts per Revolution C. Both A and B  D. None of the above. 6. Describe the different types of encoder outputs below. TTL - are logic gate circuits designed to input and output two types of signal states: high (1) and low (0). The transition between high and low signals generates TTL squarewave outputs.  Open Collector - is a sinking output. I n the ‘OFF’ state, an open collector will be grounded and in the ‘ON’ state, the open collector will float. A sourcing input is required for open collector applications.  Line Driver - is a sourcing output. This means that when in ‘ON’ state the line driv er will supply Vcc and in the ‘OFF’ state the driver will float. A sinking input is required for line driver applications.  Push-Pull - is a combination between a line driver and an open collector. In the ‘OFF’ state it will be grounded and in the on ‘ON’  state it will supply Vcc.  7. Which of the following are encoder advantages?  A. Low cost B. High resolution C. High reliability and accuracy D. Compact size E. Integration between optical and digital technology F. All of the Above  8. Quadrature channels are out of phase by how many electrical degrees?  A. 45 B. 120 C. 60 D. 90  9. List the criteria for selecting an encoder:  1. Output  2. Desired Resolution (CPR)  3. Noise and Cable Length  4. Index Channel  5. Cover/Base  10. Calculation: If an encoder has a resolution of 1024 and is mounted to a shaft of diameter 1”, what will be the pulses per inch and inch per pulse with this combination? (1024*4)/(2*pi*.5) = 1303.79 pulses per inch (1303)^-1 = .000767 inch per pulse   Encoder FAQs   Q: What is an encoder?   A:  An encoder is a sensor of mechanical motion that generates digital signals in response to motion. Q: How do you install an Encoder?   A:  For step by step tutorials on h ow to install Anaheim Automation’s encoders,  click here .  Q: What is the difference between absolute and incremental encoders?   A:  Absolute and incremental encoders are different in two ways: - Every position of an absolute encoder is unique - An absolute encoder never loses its position due to power loss or failure. Incremental encoders lose track of position upon power loss or failure Q: What is a channel?   A:  A channel is an electrical output signal from an encoder. Q: What is a quadrature?   A:  A quadrature has two output channels, with repeating squarewaves, which are out of phase by 90 electrical degrees. From the phase difference, the direction of rotation can also be determined.
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