Deck 1: Programmable Logic Controllers Plcs an Overview Difficulty: Easy Gradable: Automatic

Question 1

The voltage that would be present between the DC common and terminal 4 with the pushbutton closed woud be approximately

A)0 volts.
B)6 volts.
C)12 volts.
D)24 volts.

Answer 1

24 volts.

Question 2

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.

Answer 2

low-voltage dc.

Question 3

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

Answer 3

All of these choices are correct

Question 4

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.

Question 5

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

Question 6

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

Question 7

The devices connected to the terminals would be classified as

A)field input devices.
B)internal input instructions.
C)field output devices.
D)internal output instructions.

Question 8

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.

Question 9

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

Question 10

The diagram shown is a

A)relay schematic.
B)ladder logic program.
C)input module wiring.
D)output module wiring.

Question 11

The number of I/O points does not affect the memory size required for a PLC installation.

Question 12

Plug-in compartments allow I/0 modules to be easily connected and replaced.

Question 13

The symbol

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.

Question 14

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

Question 15

The scan time is the time required for one complete execution of the user program.

Question 16

The number and type of I/Os cannot be changed in a fixed PLC.

Question 17

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

Question 18

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

Question 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.

Question 20

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.

Question 21

PLCs have sporadic reliability.

Question 22

The diagram shown is that of a

A)hardwired relay schematic.
B)ladder logic program.
C)input module schematic.
D)output module schematic.

Question 23

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

A)Input
B)Output
C)Power supply
D)Memory

Question 24

Most PLCs can now be programmed using personal computers.

Question 25

The diagram shown is that of a

A)relay schematic.
B)ladder logic program.
C)input module wiring diagram.
D)output module wiring diagram.

Question 26

The PLC power supply module normaly 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.

Question 27

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 these choices are correct

Question 28

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 these choices are correct