PLC Quiz 3
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1. The memory organization of a PLC is often called a memory map.
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10. The addressing format for inputs and outputs is standard for all PLC models.
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11. When there is a True logic rung path, all parallel outputs in the rung become True.
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12. An internal output does not directly control an output field device.
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13. Contacts are output instructions.
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14. Ladder logic is a symbolic language.
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15. Coils are output instructions.
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16. An electromechanical relay uses electromagnetism to operate contacts.
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17. A normally closed (NC) relay contact is closed when current flows through the coil.
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18. A relay usually will have only one coil but a number of different contacts.
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19. In general, control relay contacts are designed to handle higher currents than contactors.
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2. The user program contains the logic that controls the machine operation.
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20. In general, PLC output modules are designed to switch high current loads directly.
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21. In a magnetic motor starter, the control circuit is required to handle the full load current of the motor.
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22. A selector switch is rotated to open and close contacts.
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23. Proximity switches usually sense the presence or absence of a target by means of physical contact.
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24. A small current flows through a solid-state proximity sensor even when the output is turned OFF.
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25. An inductive proximity sensor is actuated by conductive and nonconductive materials
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26. LED light sources used in photoelectric sensors normally emit a continuous beam of light.
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27. A through-beam photoelectric sensor is used to detect the light beam reflected from a target.
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28. Changes to dual-in-line (DIP) package switch settings are made mainly during installation.
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29. Ultrasonic sensors operate using high-frequency light waves.
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3. Most instructions require one word of memory.
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30. Weight strain gauges operate by detecting small changes in temperature.
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31. Reed switches are activated by magnetism.
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32. Encoders are used in applications where positions have to be precisely determined.
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33. Fiber optic sensor systems are completely immune to all forms of electrical interference.
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34. All servo motors operate in open loop.
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35. Latching relays are used when it is necessary for contacts to stay open and/or closed, even though the coil is momentarily energized.
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36. The programmed latching relay instruction is retentive; that is, if the relay is latched, it will unlatch if power is lost and then restored.
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37. There is more than one correct way to implement the ladder logic for a given control process.
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38. Digital sensors are sometimes called discrete sensors because there are two discrete states: on or off.
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39. Strain gages are used for pressure/force sensing.
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4. Scan time varies with program content and length.
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40. A thru-beam sensor has the shortest sensing range of the three types of photo sensors.
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41. Hysteresis for sensors means that there is an on point and a separate off point.
user program
42. The will account for most of the total memory of a give PLC system.
input image table file.
43. The status bit of switches and pushbuttons connected to a PLC are stored in the:
program and data files
44. The memory organization of a PLC can be divided into two broad categories?
I:1/6
45. The address for the point on the I/O module shown would be:
0, 1
46. For the input module shown, the data stored in the word corresponding to the open switch would be ___ and that for the closed switch would be ___ respectively.
reading the status of inputs, evaluating the control logic, and energizing or de-energizing the outputs.
47. The scan is normally a sequential process of:
input module.
48. For the scan process shown, the input data is provided by the:
output field devices
49. The output data is sent to the
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5. If any input signal changes state very quickly, it is possible that the controller may never be able to detect the change.
horizontal and vertical
50. The two types of patterns used to accomplish the scan function are:
calculated and stored in the PLC's memory, computed each time the END instruction is executed, and the time taken to scan inputs and outputs and execute the user program.
51. The actual scan time is:
Functional Block Diagram
52. The PLC program shown is a ___ type
is also known as the XIC instruction
53. The Examine If Closed instruction:
XIC
54. The ____ instructions always interpret a 1 status as true and a 0 status as false.
Examine If Closed instruction.
55. For the program shown, instruction A represents an:
I:2/2
56. The most likely module address for LS1 is:
four
57. For the matrix limitation diagram shown, the maximum number of parallel rows allowed is:
Y = (AB) + (ACD) + (DE) + (BCE)
58. The Boolean equation for the logic represented in the ladder diagram can be expressed as:
one
59. The address I:1/3 identifies an input module residing in slot ___ of the PLC chassis.
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6. Misunderstanding the way the PLC scans a program can cause programming bugs.
the instruction is true.
60. The highlighted rungs in the program rung shown indicate:
continuously ON
61. When a program rung consists of an output instruction only, the output would then be:
branches.
62. Parallel connections of ladder logic are typically called:
rung.
63. Each complete horizontal line of a ladder diagram is generally referred to as a(n):
the limit switch is open
64. A normally open limit switch is wired to an input module, and programmed using XIO instruction. The instruction will be true when:
energized.
65. In the relay shown, the coil would be considered to be:
energized, the red light is on, and the green light is off.
66. In the hardwired relay control circuit shown, when the switch is closed, CR coil is:
part of the control circuit and designed to handle the full load current of the motor.
67. In the motor starter circuit shown, the main contacts M are:
the switch is not actuated
68. The abbreviations NO (normally open) and NC (normally closed) represent the electrical state of switch contacts when:
break-before-make pushbutton.
69. The pushbutton symbol shown, would be classified as a(n):
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7. It takes the processor exactly the same amount of time to examine different types of instructions.
selector switch.
70. The device represented by the symbol is a:
limit switch.
71. The symbol shown is that for a:
level switch
72. The symbol shown is that for a:
temperature switch
73. The symbol shown is that for a:
pressure switch
74. The symbol shown is that for a:
proximity switch
75. The application shown is a typical application for a:
solenoid.
76. The symbol shown is that for a:
motor starter coil.
77. The symbol shown is that for a:
proximity sensor.
78. The symbol shown is that for a:
verify the output switching action
79. Most proximity switches come equipped with an LED status indicator to:
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8. Both normally open and normally closed pushbuttons can be represented by the XIC or XIO instruction.
a permanent or electromagnet
80. The most common actuator for a reed switch is:
photoconductive cell
81. The light sensor shown would be classified as a:
transmitter, receiver
82. For the photoelectric sensor part 1 is the ___ and part 2 is the___.
resistance.
83. The force applied to a strain gauge causes it to bend and change its:
produces a small dc voltage
84. A thermocouple, when heated:
small generator
85. A tachometer normally refers to a(n) ____ used for speed measurement.
converts an electrical signal into mechanical movement
86. An actuator is a device that:
oil flow, water flow, and air flow.
87. Solenoid valves are available to control:
stepper motor
88. A(n) ____ converts electrical pulses applied to it into discrete rotor movements.
operate in the closed-loop mode.
89. All servo motors:
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9. The rung condition and OTE instruction are false if no logical continuity path has been established.
keep the starter coil energized when the start button is released.
90. The purpose of the M contact shown in the circuit is to
latch and unlatch outputs
91. For the programmed latching operation shown, which two instructions must have the same address?
I:1/3
92. For the program shown, what is the address of the instruction associated with the pressure switch?
either the pressure switch is closed or the selector switch is closed and rung 1 is True
93. Rung 2 will be True whenever:
PLC programmed rung 2 is False
94. With reference to the circuit and equivalent PLC program, when LS2 is actuated and LS1 is not:
PLC program rung 3 is True
95. When both LS1 and LS2 are actuated: