Copyright (c) 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 1CHAPTER 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: 1. b
a) microcomputers. c) analog controllers. b) relay control panels. d) digital controllers. 2. Basically, the function of a PLC is to: 2. d
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. 3. Modifying relay-type process control circuits usually involves 3. a
changing the: a) circuit wiring. b) input circuit modules. c) output circuit modules. d) circuit operating voltage levels. Copyright (c) 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 24. Which of the following is not an advantage that PLCs 4. c
offer over the conventional relay-type of control system? a) Smaller size c) Higher current capacity b) Less expensive d) More reliable 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. Copyright (c) 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 37. PLC proprietary architecture 7. d
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. 8. The output interface module connects to: 8. b
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. 9. Field or real-world devices refer to: 9.d
a) input devices only. b) output devices only. c) load devices only. d) all devices that are physically wired to the PLC. 10. The power required to operate the logic circuits 10 c
of the processor unit is typically: a) low voltage ac. c) low voltage dc. b) high voltage ac. d) high voltage dc. Copyright (c) 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 411. The control plan stored in the PLC is called: 11. a
a) a program. c) FORTRAN. b) a Boolean ladder. d) a microprocessor. 12. The programming device: 12. d
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. 13. The programming device must be connected to the controller: 13. d
a) at all times. c) when monitoring a program. b) when entering a program. d) both b and c. 14. The symbol in a ladder logic diagram: 14. a
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. 15. The symbol in a ladder logic diagram 15. b
represents a: a) set of normally closed contacts. b) virtual relay coil. c) seal-in contact. d) field input sensing device.
a) microcomputers. c) analog controllers. b) relay control panels. d) digital controllers. 2. Basically, the function of a PLC is to: 2. d
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. 3. Modifying relay-type process control circuits usually involves 3. a
changing the: a) circuit wiring. b) input circuit modules. c) output circuit modules. d) circuit operating voltage levels. Copyright (c) 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 24. Which of the following is not an advantage that PLCs 4. c
offer over the conventional relay-type of control system? a) Smaller size c) Higher current capacity b) Less expensive d) More reliable 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. Copyright (c) 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 37. PLC proprietary architecture 7. d
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. 8. The output interface module connects to: 8. b
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. 9. Field or real-world devices refer to: 9.d
a) input devices only. b) output devices only. c) load devices only. d) all devices that are physically wired to the PLC. 10. The power required to operate the logic circuits 10 c
of the processor unit is typically: a) low voltage ac. c) low voltage dc. b) high voltage ac. d) high voltage dc. Copyright (c) 2017 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. 411. The control plan stored in the PLC is called: 11. a
a) a program. c) FORTRAN. b) a Boolean ladder. d) a microprocessor. 12. The programming device: 12. d
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. 13. The programming device must be connected to the controller: 13. d
a) at all times. c) when monitoring a program. b) when entering a program. d) both b and c. 14. The symbol in a ladder logic diagram: 14. a
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. 15. The symbol in a ladder logic diagram 15. b
represents a: a) set of normally closed contacts. b) virtual relay coil. c) seal-in contact. d) field input sensing device.
