Name: ________________________ Class: ___________________ Date: __________
ID: A
MECH 1500 Quiz 3 Review
True/False
Indicate whether the statement is true or false.
____
1.
The memory organization of a PLC is often called a memory map.
____
2.
The user program contains the logic that controls the machine operation.
____
3.
Most instructions require one word of memory.
____
4.
Scan time varies with program content and length.
____
5.
If any input signal changes state very quickly, it is possible that the controller may
never be able to detect the change.
____
6.
Misunderstanding the way the PLC scans a program can cause programming bugs.
____
7.
It takes the processor exactly the same amount of time to examine different types of
instructions.
____
8.
Both normally open and normally closed pushbuttons can be represented by the XIC
or XIO instruction.
____
9.
The rung condition and OTE instruction are false if no logical continuity path has
been established.
____ 10.
The addressing format for inputs and outputs is standard for all PLC models.
____ 11.
When there is a True logic rung path, all parallel outputs in the rung become True.
____ 12.
An internal output does not directly control an output field device.
____ 13.
Contacts are output instructions.
____ 14.
Ladder logic is a symbolic language.
1
Name: ________________________
ID: A
____ 15.
Coils are output instructions.
____ 16.
An electromechanical relay uses electromagnetism to operate contacts.
____ 17.
A normally closed (NC) relay contact is closed when current flows through the coil.
____ 18.
A relay usually will have only one coil but a number of different contacts.
____ 19.
In general, control relay contacts are designed to handle higher currents than
contactors.
____ 20.
In general, PLC output modules are designed to switch high current loads directly.
____ 21.
In a magnetic motor starter, the control circuit is required to handle the full load
current of the motor.
____ 22.
A selector switch is rotated to open and close contacts.
____ 23.
Proximity switches usually sense the presence or absence of a target by means of
physical contact.
____ 24.
A small current flows through a solid-state proximity sensor even when the output is
turned OFF.
____ 25.
An inductive proximity sensor is actuated by conductive and nonconductive materials
____ 26.
LED light sources used in photoelectric sensors normally emit a continuous beam of
light.
____ 27.
A through-beam photoelectric sensor is used to detect the light beam reflected from a
target.
____ 28.
Changes to dual-in-line (DIP) package switch settings are made mainly during
installation.
____ 29.
Ultrasonic sensors operate using high-frequency light waves.
2
Name: ________________________
ID: A
____ 30.
Weight strain gauges operate by detecting small changes in temperature.
____ 31.
Reed switches are activated by magnetism.
____ 32.
Encoders are used in applications where positions have to be precisely determined.
____ 33.
Fiber optic sensor systems are completely immune to all forms of electrical
interference.
____ 34.
All servo motors operate in open loop.
____ 35.
Latching relays are used when it is necessary for contacts to stay open and/or closed,
even though the coil is momentarily energized.
____ 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.
____ 37.
There is more than one correct way to implement the ladder logic for a given control
process.
____ 38.
Digital sensors are sometimes called discrete sensors because there are two discrete
states: on or off.
____ 39.
Strain gages are used for pressure/force sensing.
____ 40.
A thru-beam sensor has the shortest sensing range of the three types of photo sensors.
____ 41.
Hysteresis for sensors means that there is an on point and a separate off point.
Multiple Choice
Identify the choice that best completes the statement or answers the question.
____ 42.
The
will account for most of the total memory of a give PLC system.
a. input image table file
c. user program
b. output image table file
d. internal operating instructions
____ 43.
The status bit of switches and pushbuttons connected to a PLC are stored in the:
a. input image table file.
c. user program.
b. output image table file.
d. all of these.
3
Name: ________________________
ID: A
____ 44.
The memory organization of a PLC can be divided into two broad categories?
a. input and output image files
c. program and data files
b. timer and counter files
d. control and integer
____ 45.
The address for the point on the I/O module shown would be:
a. I:6/1
c. O:6/1
b. I:1/6
d. O:1/6
a.
b.
____ 46.
I:6/1
I:1/6
c.
d.
O:6/1
O:1/6
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.
a.
b.
1, 1
0, 1
c.
d.
4
0, 0
1, 0
Name: ________________________
ID: A
____ 47.
The scan is normally a sequential process of:
a. reading the control logic, evaluating the outputs, and updating
the inputs.
b. writing the control logic, evaluating the outputs, and updating
the inputs.
c. reading/writing the status of inputs and updating the outputs.
d. reading the status of inputs, evaluating the control logic, and
energizing or de-energizing the outputs.
____ 48.
For the scan process shown, the input data is provided by the:
a.
b.
____ 49.
____ 50.
ladder program.
output module.
The output data is sent to the
a. output field devices.
b. output module.
c.
d.
c.
d.
input module.
all of these.
input module.
ladder program.
The two types of patterns used to accomplish the scan function are:
a. horizontal and vertical.
c. up and down.
b. left and right.
d. input and output.
5
Name: ________________________
ID: A
____ 51.
The actual scan time is:
a. calculated and stored in the PLC's memory.
b. computed each time the END instruction is executed.
c. the time taken to scan inputs and outputs and execute the user
program.
d. all of these.
____ 52.
The PLC program shown is a ___ type.
a.
b.
Structured Text
Functional Block Diagram
c.
d.
Ladder Diagram
Structured Text
____ 53.
The Examine If Closed instruction:
a. is also known as the Examine-On instruction.
b. is also known as the XIC instruction.
c. looks and operates like a normally open relay contact.
d. all of these.
____ 54.
The ____ instructions always interpret a 1 status as true and a 0 status as false.
a. XIC
c. contact
b. XIO
d. all of these
6
Name: ________________________
____ 55.
For the program shown, instruction A represents an:
a.
b.
____ 56.
ID: A
Examine If Closed instruction.
Examine If Open instruction.
c.
d.
Output Energize instruction.
Input Energize instruction.
The most likely module address for LS1 is:
a.
b.
LS1 I2
LS1 O2
c.
d.
7
I:2/2
O:2/2
Name: ________________________
____ 57.
For the matrix limitation diagram shown, the maximum number of parallel rows
allowed is:
a.
b.
c.
d.
____ 58.
one
four
five
limited only by the memory size
The Boolean equation for the logic represented in the ladder diagram can be
expressed as:
a.
b.
c.
d.
____ 59.
ID: A
Y = (AB) + (ACD) + (DE)
Y = (AB) + (ACD) + (DE) + (BCE)
Y = (AB) + (AC) + (AD) + (ED)
Y= (AB) + (CD) + E
The address I:1/3 identifies an input module residing in
slot ___ of the PLC chassis.
a. zero
c. two
b. one
d. three
8
Name: ________________________
____ 60.
ID: A
The highlighted rungs in the program rung shown indicate:
a.
b.
c.
d.
the instruction is true.
the instruction is false.
the instruction does not have logic continuity.
both b and c.
____ 61.
When a program rung consists of an output instruction only, the output would then
be:
a. continuously ON.
c. shorted.
b. continuously OFF.
d. both a and c.
____ 62.
Parallel connections of ladder logic are typically called:
a. rungs.
c. coils.
b. networks.
d. branches.
____ 63.
Each complete horizontal line of a ladder diagram is generally referred to as a(n):
a. rung.
c. input.
b. branch.
d. output.
____ 64.
A normally open limit switch is wired to an input module, and programmed using
XIO instruction. The instruction will be true when:
a. power is applied and the PLC is in the run mode
b. the limit switch is closed
c. the limit switch is open
d. never
9
Name: ________________________
____ 65.
In the relay shown, the coil would be considered to be:
a.
b.
____ 66.
ID: A
energized.
de-energized.
c.
d.
operated from an ac source.
both a and c.
In the hardwired relay control circuit shown, when the switch is closed, CR coil is:
a.
b.
c.
d.
energized, and the red and green lights are both on.
de-energized, the red light is off, and the green light is on.
energized, the red light is on, and the green light is off.
energized, the red light is off, and the green light is on.
10
Name: ________________________
____ 67.
ID: A
In the motor starter circuit shown, the main contacts M are:
a.
b.
c.
d.
part of the power circuit.
part of the control circuit.
designed to handle the full load current of the motor.
both a and c.
____ 68.
The abbreviations NO (normally open) and NC (normally closed) represent the
electrical state of switch contacts when:
a. power is applied.
c. the switch is actuated.
b. power is not applied.
d. the switch is not actuated
____ 69.
The pushbutton symbol shown, would be classified as a(n):
a.
b.
____ 70.
NO pushbutton.
NC pushbutton.
c.
d.
break-before-make pushbutton.
ON/OFF pushbutton.
The device represented by the symbol is a:
a.
b.
drum switch.
selector switch.
c)
d)
c.
d.
11
sequence switch.
toggle switch.
Name: ________________________
____ 71.
The symbol shown is that for a:
a.
b.
____ 72.
b.
b.
d.
limit switch.
level switch.
pressure switch.
temperature switch.
c.
d.
proximity switch.
level switch.
proximity switch.
temperature switch.
c.
d.
limit switch.
level switch.
The symbol shown is that for a:
a.
b.
____ 75.
c.
The symbol shown is that for a:
a.
____ 74.
pressure switch.
temperature switch.
The symbol shown is that for a:
a.
____ 73.
ID: A
pressure switch.
temperature switch.
c.
d.
limit switch.
proximity switch.
The application shown is a typical application for a:
a.
b.
level switch.
temperature switch.
c.
d.
12
proximity switch.
limit switch.
Name: ________________________
____ 76.
The symbol shown is that for a:
a.
b.
____ 77.
heater.
horn.
c.
d.
solenoid.
motor.
The symbol shown is that for a:
a.
b.
____ 78.
ID: A
solenoid valve.
motor starter coil.
c.
d.
overload relay coil.
overload relay contact.
The symbol shown is that for a:
a.
b.
light sensor.
heat sensor.
c.
d.
pressure sensor.
proximity sensor.
____ 79.
Most proximity switches come equipped with an LED status indicator to:
a. indicate that power is being applied to the switch.
b. indicate that the target is within sensing range.
c. indicate a blown fuse within the switch.
d. verify the output switching action.
____ 80.
The most common actuator for a reed switch is:
a. a permanent or electromagnet.
c. application of pressure.
b. a light beam.
d. a heat source.
13
Name: ________________________
____ 81.
The light sensor shown would be classified as a:
a.
b.
____ 82.
ID: A
solar cell
photoconductive cell
c.
d.
photovoltaic cell
all of these
For the photoelectric sensor part 1 is the ___ and part 2 is the___.
a.
b.
input, output
primary, secondary
c.
d.
transmitter, receiver
high side, low side
____ 83.
The force applied to a strain gauge causes it to bend and change its:
a. temperature.
c. voltage.
b. resistance.
d. current.
____ 84.
A thermocouple, when heated:
a. produces a small dc voltage.
b. produces a small ac voltage.
c.
d.
increases its resistance value.
decreases its resistance value.
____ 85.
A tachometer normally refers to a(n) ____ used for speed measurement.
a. load cell
c. ultrasonic sensor
b. capacitive proximity sensor
d. small generator
____ 86.
An actuator is a device that:
a. changes AC to DC
b. changes DC to AC
c. converts an electrical signal into mechanical movement
d. converts mechanical movement into an electrical signal
14
Name: ________________________
ID: A
____ 87.
Solenoid valves are available to control:
a. oil flow.
c. water flow.
b. air flow.
d. all of these
____ 88.
A(n) ____ converts electrical pulses applied to it into discrete rotor movements.
a. tachometer
c. stepper motor
b. solenoid
d. electronic magnetic flowmeter
____ 89.
All servo motors:
a. operate in the closed-loop mode.
b. operate in the open-loop mode.
c. operate without feedback.
d. both b and c.
____ 90.
The purpose of the M contact shown in the circuit is to
a.
b.
c.
d.
____ 91.
open the circuit in the case of a motor overload.
start the motor from a remote location.
keep the starter coil energized when the start button is released.
keep the starter coil de-energized when the start button is released.
For the programmed latching operation shown, which two instructions must have the
same address?
a.
b.
ON and OFF inputs.
latch and unlatch outputs
c.
d.
15
ON input and latch output
OFF input and unlatch output
Name: ________________________
____ 92.
For the program shown, what is the address of the instruction associated with the
pressure switch?
a.
b.
____ 93.
ID: A
I:1/0
I:1/1
c.
d.
I:1/2
I:1/3
Rung 2 will be True whenever:
a.
b.
c.
d.
the pressure switch is closed.
the pushbutton is closed.
the selector switch is closed and rung 1 is True.
either a or c.
16
Name: ________________________
____ 94.
With reference to the circuit and equivalent PLC program, when LS2 is actuated and
LS1 is not:
a.
b.
c.
d.
____ 95.
ID: A
PLC input I:1/2 is True.
PLC programmed rung 2 is False.
pilot light PL2 is ON.
both a and c.
When both LS1 and LS2 are actuated:
a.
b.
PLC program rung 2 is True.
PLC program rung 3 is True.
c.
d.
17
PLC program rung 4 is True.
PLC program rung 5 is True.
ID: A
MECH 1500 Quiz 3 Review
Answer Section
TRUE/FALSE
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
ANS:
ANS:
ANS:
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ANS:
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ANS:
T
T
T
T
T
T
F
T
T
F
T
T
F
T
T
T
F
T
F
F
F
T
F
T
F
T
F
T
F
T
T
T
T
F
T
F
T
T
T
PTS:
PTS:
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PTS:
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
ID: A
40. ANS: F
41. ANS: T
PTS: 1
PTS: 1
MULTIPLE CHOICE
42.
43.
44.
45.
46.
47.
48.
49.
50.
51.
52.
53.
54.
55.
56.
57.
58.
59.
60.
61.
62.
63.
64.
65.
66.
67.
68.
69.
70.
71.
72.
73.
74.
75.
76.
77.
78.
79.
80.
ANS:
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ANS:
ANS:
C
A
C
B
B
D
C
A
A
D
B
B
A
A
C
B
B
B
A
A
D
A
C
A
C
D
D
C
B
C
D
B
A
C
C
B
D
D
A
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
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1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
ID: A
81.
82.
83.
84.
85.
86.
87.
88.
89.
90.
91.
92.
93.
94.
95.
ANS:
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ANS:
B
C
B
A
D
C
D
C
A
C
B
D
D
B
B
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
3