SOLUTIONS SOLUTIONS
TEST BANK TEST BANK
Solutions for Programmable Logic Controllers - 6 - Petruzella - Chapter 01 1) The number and type of I/Os cannot be changed in a fixed PLC. ⊚ true ⊚ false 2) In a PLC system, there is a physical connection between field input devices and output
devices. ⊚ true ⊚ false 3) The scan time is the time required for one complete execution of the user program. ⊚ true ⊚ false 4) The input/output system forms the interfaces through which field devices are connected to
the controller. ⊚ true ⊚ false 5) Plug-in compartments allow I/O modules to be easily connected and replaced. ⊚ true ⊚ false 6) A personal computer communicates with the PLC processor via a serial or parallel data
communications link. ⊚ true ⊚ false 7) The programming device must be connected to the controller to run the program. ⊚ true ⊚ false 8) PLC systems usually require as much space in an enclosure as equivalent hardwired relay
systems. ⊚ true ⊚ false 9) A PLC is basically a computer designed for use in electrical control applications. ⊚ true ⊚ false
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Solutions for Programmable Logic Controllers - 6 - Petruzella - Chapter 01 10) The programmable controller operates in real time. ⊚ true ⊚ false 11) One disadvantage of modular I/O is its lack of flexibility. ⊚ true ⊚ false 12) A PLC power supply module does not normally supply power to the field devices. ⊚ true ⊚ false 13) Removing the programming device from the PLC will not affect the operation of the user
program. ⊚ true ⊚ false 14) Software installed and run on a personal computer can be used to write a PLC program. ⊚ true ⊚ false 15) The instruction set for a particular PLC lists the types of instructions supported. ⊚ true ⊚ false 16) When dealing with PLC memory, 1 K of memory represents 1024. ⊚ true ⊚ false 17) The number of I/O points does not affect the memory size required for a PLC installation. ⊚ true ⊚ false 18) PLCs were originally designed as replacements for A) microcomputers. B) relay control panels. C) analog controllers. D) digital controllers.
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Solutions for Programmable Logic Controllers - 6 - Petruzella - Chapter 01 19) 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. 20) 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. 21) Which of the following is not an advantage that PLCs offer over the conventional relay-type
of control system? A) Smaller size B) Less expensive C) Higher current capacity D) More reliable 22) The main difference between a PLC and relay control system 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. 23) The central processing unit 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. 24) 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 choices are correct
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Solutions for Programmable Logic Controllers - 6 - Petruzella - Chapter 01 25) 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 these choices are correct 26) 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. 27) 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. 28) The control plan stored in the PLC is called A) a program. B) a Boolean ladder. C) FORTRAN. D) a microprocessor. 29) 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 these choices are correct 30) The programming device must be connected to the controller A) at all times. B) when entering a program. C) when monitoring a program. D) both when entering a program and when monitoring a program.
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Solutions for Programmable Logic Controllers - 6 - Petruzella - Chapter 01 31) <p>The symbol in a ladder logic diagram</p> 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. 32) <p> The symbol A) B) C) D)
in a ladder logic diagram represents a
set of normally closed contacts. virtual relay coil. seal-in contact. field input sensing device.
33) When a field device contact connected to the input module closes 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) None of these choices are correct 34) At the start of the PLC scan, the 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. 35) 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. 36) 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. D) All of these choices are correct
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Solutions for Programmable Logic Controllers - 6 - Petruzella - Chapter 01 37) 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 these choices are correct 38) 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. 39) Block No.1 of the PLC block diagram represents the
A) B) C) D)
CPU unit. programming device. input module. output module.
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Solutions for Programmable Logic Controllers - 6 - Petruzella - Chapter 01 42) Block No. 4 of the PLC block diagram represents the
A) B) C) D)
memory. programming device. input module. CPU.
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Solutions for Programmable Logic Controllers - 6 - Petruzella - Chapter 01 43) Block No. 5 of the PLC block diagram represents the
A) B) C) D)
memory. power supply module. input module. output module.
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