Solution Manual Programmable Logic Controllers 4Th Edition By Frank Petruzella – Test Bank

Complete Test Bank With Answers

 

 

Sample Questions Posted Below

 

CHAPTER 1

Programmable Logic Controllers (PLCs): An Overview

TEST 1 . 1

Choose the letter that best completes the statement. Answer

1. PLCs were originally designed as replacements for: a) microcomputers. c) analog controllers.

b) relay control panels. d) digital controllers.

1. b

2. Basically, the function of a PLC is to: a) amplify various weak signal sources.

b) control a high voltage output with a low voltage input.

c) control the speed of motors.

d) make logical decisions and control outputs based on them.

2. d

3. Modifying relay-type process control circuits usually involves changing the:

a) circuit wiring.

b) input circuit modules.

c) output circuit modules.

d) circuit operating voltage levels.

3. a

14. Which of the following is not an advantage that PLCs offer over the conventional relay-type of control system?

a) Smaller size c) Higher current capacity

b) Less expensive d) More reliable

4. c

5. The main difference between a PLC and relay control system 5. d

is that:

a) different types of input devices are used.

b) different types of output devices are used.

c) different input and output voltage levels are used.

d) one uses hardwired relay control logic and the other uses programmed

instructions.

6. The central processing unit: 6. a

a) looks at the inputs, makes the decisions based on the program,

and sets the outputs.

b) looks at the outputs, makes the decisions based on the program, and sets

the inputs.

c) serves only to store the program in memory.

d) serves only to supply power to the backplane.

27. PLC proprietary architecture a) is the opposite to open architecture .

b) makes it more difficult to connect to devices made by other

PLC manufacturers.

c) does not allow programs to be interchanged between different PLC

manufacturers.

d) all of these.

7. d

8. The output interface module connects to: a) sensing devices such as switches or pushbuttons.

b) load devices such as lamps or solenoids.

c) a programming device such as a computer.

d) all of the above.

8. b

9. Field or real-world devices refer to: a) input devices only.

b) output devices only.

c) load devices only.

d) all devices that are physically wired to the PLC.

9. d

10. The power required to operate the logic circuits of the processor unit is typically:

a) low voltage ac. b) high voltage ac. c) low voltage dc.

d) high voltage dc.

10 c

311. The control plan stored in the PLC is called: a) a program. c) FORTRAN.

b) a Boolean ladder. d) a microprocessor.

11. a

12. The programming device: a) is used to enter the program into the memory of the processor.

b) is commonly a personal computer.

c) can be a hand-held device.

d) all of the above.

12. d

13. The programming device must be connected to the controller: a) at all times. c) when monitoring a program.

b) when entering a program. d) both b and c.

13. d

14. The symbol in a ladder logic diagram: a) can be thought of as a normally open contact.

b) represents a capacitor.

c) is always at logic 0.

d) is always at logic 1.

14. a

15. The represents a:

a) set of normally closed contacts.

b) virtual relay coil.

c) seal-in contact.

d) field input sensing device.

symbol in a ladder logic diagram 15. b

416. When a field device contact connected to the input

module closes: 16. b

a) a logic 1 is recorded in the memory location of the coil with the same

address.

b) a logic 1 is recorded in the memory location of the contact with the same

address.

c) a logic 0 is recorded in the memory location of the coil with the same

address.

d) a logic 1 is recorded in the memory location of the contact with the same

address.

17. At the start of the PLC scan the: 17. a

a) status of all inputs are read.

b) status of all outputs are updated.

c) program is executed.

d) diagnostics and communications tasks are executed.

18. The scan time is the time required: a) to record the status of all input devices.

b) to record the status of all output devices.

c) to execute one cycle of the total program.

d) for the information to pass from input to output.

18. c

19. Unlike personal computers, PLCs are: a) equipped with input and output modules.

b) equipped with a control programming language.

c) designed for the industrial environment.

19. d

5d) all of the above.

20. A human machine interface (HMI) a) allows the user to monitor a process.

b) allows the user to control a process.

c) can provide a graphical representation of a process .

d) all of the above.

20. d

21. Programmable logic controllers are categorized according to the

a) number of I/O points.

b) current rating of I/O modules.

c) power rating of the I/O modules.

d) cost of the I/O modules.

21. a

22-1. In the PLC block diagram of Figure 1-1, block No.1

represents the: 22-1 b

a) CPU unit. c) input module.

b) programming device. d) output module.

22-2. Block No. 2 represents the: a) memory.

b) programming device.

c) input module.

d) power supply module.

22-2 a

622-3. Block No. 3 represents the: a) CPU unit.

b) programming device.

c) input module.

d) output module.

22-4. Block No. 4 represents the: a) memory.

b) programming device.

c) input module.

d) CPU.

22-5. Block No. 5 represents the: a) memory.

b) power supply module.

c) input module.

d) output module.

22-6. Block No. 6 represents the: a) processor module.

b) power supply module.

c) input module.

d) output module.

22-3 a

22-4 c

22-5 d

22-6 b

7Figure 1-1 Block diagram for question 22.

23.1. The diagram of Figure 1-2 is that of a(n): a) relay schematic.

b) ladder logic program.

c) input module wiring.

d) output module wiring.

23-1 c

23-2. The voltage that would be present between the DC common and

terminal 4 with the pushbutton open would be approximately: a) 0 volts.

b) 6 volts.

c) 12 volts.

d) 24 volts.

23-2 a

823-3. The voltage that would be present between the DC common and

terminal 4 with the pushbutton closed would be approximately: a) 0 volts.

b) 6 volts.

c) 12 volts.

d) 24 volts.

23-3 d

23-4. The devices connected to the terminals would be

classified as: 23-4 a

a) field input devices.

b) internal input instructions.

c) field output devices.

d) internal output instructions.

Figure 1-2 Diagram for question 23.

924-1. The diagram of Figure 1-3 is that of a a) hardwired relay schematic. c) input module schematic.

b) ladder logic program. d) output module schematic.

24-1 a

24-2. In order to energize the starter coil: a) the pressure switch, and the temperature switch, and the manual

pushbutton must be closed.

b) the pressure switch, or the temperature switch, or the manual

pushbutton must be closed.

c) the pressure switch, and the temperature switch, or the manual

pushbutton must be closed.

d) all of the above.

24-2 c

Figure 1-3 Diagram for question 24.

25-1.The diagram of Figure 1-4 is that of a: a) relay schematic. b) ladder logic program. 25-1 b

c) input module wiring diagram

d) output module wiring diagram

1025-2. For there to be is a continuous logic path from left

to right across the rung: a) I/1, 1/2, and 1/3 must all be at logic 1.

b) I/1, 1/2, and 1/3 must all be at logic 0.

c) I/1 and 1/2 or 1/3 must be at logic 1.

d) I/1 and 1/2 or 1/3 will be at logic 0.

25-2 c

Figure 1-4 Diagram for question 25.

26. The PLC power supply module normally is rated to provide the power for:

a) all field devices. b) input field devices only. c) output field devices only

d) PLC backplane and I/O modules.

26 d

27. Which module of the PLC is responsible for performing logical operations?

a) Processor c) Output

b) Input d) Power supply

27 a

1128. Which module of the PLC connects directly to field devices such as pilot lights, motor starters, and solenoids?

a) Input c) Power supply

b) Output d) Memory

29. ______ I/Os are typical of small PLCs that come in one package with no separate removable units.

a) Fixed c) Digital

b) Modular d) Analog

30. PLC software that runs on a personal computer can be used to: a) write a PLC program.

b) document a PLC program.

c) monitor the control process.

d) all of the above.

31. A control management PLC application normally requires a: a) micro-size PLC. c) medium-size PLC.

b) small-size PLC. d) large-size PLC.

32. Which of the following is not a factor effecting the memory size needed for a particular PLC installation?

a) Voltage rating of field devices c) Size of control program

b) Number of I/O points d) Supervisory functions required

28 b

29 a

30 d

31 d

32 a

12CHAPTER 1

Programmable Logic Controllers (PLCs): An Overview

TEST 1 . 2

Place the answers to the following questions in the

answer column at the right. Answer

1. Programmable logic controllers were originally designed to perform logic functions previously

accomplished by _______.

1. relays

2. The number and type of I/Os cannot be changed in a fixed PLC. (True or False)

2. True

3. In a PLC system, there is a physical connection between field input devices and output devices.

(True or False)

3. False

4. Identify the following electrical components by specifying

whether they are input field devices or output field devices.

a) pushbutton 4a. Input

b) solenoid 4b. Output

c) pilot lamp 4c. Output

d) selector switch 4d. Input

135. In a typical ladder logic program the symbols represent the (a) __ and the numbers represent the (b) ___.

5a. instructions

5b. addresses

6. The scan time is the time required for one complete execution of the user program. (True or False)

6. True

7. The input/output system forms the interfaces through which field devices are connected to the

controller. (True or False)

7. True

8. ____is the process of reading inputs, executing the program, and setting outputs on a

continuous basis.

8. Scan

9. The abbreviation I/O means (a) ___ and 9a. Inputs

(b) ___. 9b. Outputs

10. Plug-in compartments allow I/O modules to be easily connected and replaced. (True or False)

10. True

11. To operate the program, the controller is placed in the ___ mode.

11. RUN

12. If there is no continuous logic path from left to right on 12. zero

14the program rung, the output coil status is set to ___.

13. Changes to hardwired relay control systems usually require some ___ of the system.

13. rewiring

14. A personal computer communicates with the PLC processor via a serial or parallel data communications

link. (True or False)

14. True

15. The programming device must be connected to the controller to run the program. (True or False)

15. False

16. Incoming control signals to a PLC are called _____. 16. Inputs

17. Signals going out from a PLC to control field devices are called _____ .

17. Outputs

18. PLC systems usually require as much space in an enclosure as equivalent hardwired relay systems.

(True or False)

18. False

19. The term central processing unit is often used interchangeably with the term ___.

19. processor

20. What is the name of the most common programming language used in PLCs?

20. Relay Ladder Logic

1521. The PLC program is stored in the processor module’s ___.

22. A PLC is basically a computer designed for use in electrical control applications. (True or False)

23. The programmable controller operates in real time. (True or False)

24. When a module is slid into a PLC rack, it makes electrical connection with the _____ .

25. One disadvantage of modular I/O is its lack of flexibility. (True or False)

26. A PLC power supply module does not normally supply power to the field devices. (True or False)

27. Removing the programming device from the PLC will not affect the operation of the user program.

(True or False)

28. Software installed and run on a personal computer can be used to write a PLC program.

(True or False)

29. The instruction set for a particular PLC lists the 21.memory

22. True

23. True

24. backplane

25. False

26. True

27. True

28. True

29. True

16types of instructions supported. (True or False)

30. When dealing with PLC memory, one K of memory represents 1024. (True or False)

30. True

31. The number of I/O points does not affect the memory size required for a PLC installation. (True or False)

31. False

17Programming Assignments

For Chapter 1

1a) On a separate sheet of paper, draw an I/O wiring diagram and ladder

logic program for the relay schematic shown in Figure 1-5. Use the field

devices with the appropriate addressing for the PLC trainer you will be

working with.

b) Enter the program into the PLC and prove its operation.

Figure 1-5 Relay schematic for assignment 1.

1a), 1b) Answers will vary according to the PLC used.

2a) On a separate sheet of paper, draw a ladder logic diagram for the

modified relay ladder schematic shown in Figure 1-6.

b) Enter the program into the PLC and prove its operation.

2a), 1b) Answers will vary according to the PLC used.

18Figure 1-6 Relay schematic for assignment 2.

3a. On a separate sheet of paper, draw a ladder logic program of the relay

schematic circuit altered so that the manual pushbutton, pressure switch, and

temperature switch all must be closed to permit operation of the motor.

3b. Enter the program into the PLC and prove its operation.

3a), 1b) Answers will vary according to the PLC used.

4a. On a separate sheet of paper, draw a modified ladder logic program for

the relay schematic circuit altered so that the motor will operate when either

the manual pushbutton, pressure switch, or temperature switch is closed.

4-b. Enter the program into the PLC and prove its operation.

4a), 1b) Answers will vary according to the PLC used.

19