Encoders Questions and Answers

PLC
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Encoders Questions and Answers

Encoder%20Questions%20and%20Answers

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. In 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 driver 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?

(10244)/(2pi*.5) = 1303.79 pulses per inch
(1303)^-1 = .000767 inch per pulse

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