Deck 1: Programmable Logic Controllers Plcs: an Overview

Question 1

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

Answer 1

True

Question 2

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

Answer 2

True

Question 3

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.

Answer 3

D

Question 4

A PLC power supply module does not normally supply power to the field devices.

Question 5

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

Question 6

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

Question 7

The programmable controller operates in real time.

Question 8

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

Question 9

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

Question 10

When dealing with PLC memory,one K of memory represents 1024.

Question 11

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.

Question 12

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

Question 13

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

Question 14

A PLC is basically a computer designed for use in electrical control applications.

Question 15

One disadvantage of modular I/O is its lack of flexibility.

Question 16

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

Question 17

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

Question 18

The instruction set for a particular PLC lists the types of instructions supported.

Question 19

PLCs were originally designed as replacements for:

A)microcomputers.
B)relay control panels.
C)analog controllers.
D)digital controllers.

Question 20

The programming device must be connected to the controller to run the program.

Question 21

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.

Question 22

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.

Question 23

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 are correct.

Question 24

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 25

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.

Question 26

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 b and c.

Question 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 the above.

Question 28

Block No.2 of the PLC block diagram represents the:

A)memory.
B)programming device.
C)input module.
D)power supply module.

Question 29

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 30

The symbol in a ladder logic diagram represents a:

A)set of normally closed contacts.
B)virtual relay coil.
C)seal-in contact.
D)field input sensing device.

Question 31

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.

Question 32

The control plan stored in the PLC is called:

A)a program.
B)a Boolean ladder.
C)FORTRAN.
D)a microprocessor.

Question 33

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.

Question 34

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 the above.

Question 35

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.

Question 36

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.

Question 37

Block No.1 of the PLC block diagram represents the:

A)CPU unit.
B)programming device.
C)input module.
D)output module.

Question 38

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 39

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.

Question 40

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.

Question 41

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.

Question 42

Block No.5 of the PLC block diagram represents the:

A)memory.
B)power supply module.
C)input module.
D)output module.

Question 43

Block No.3 of the PLC block diagram represents the:

A)CPU unit.
B)programming device.
C)input module.
D)output module.

Question 44

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

A)Voltage rating of field devices
B)Number of I/O points
C)Size of control program
D)Supervisory functions

Question 45

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 46

A control management PLC application normally requires a:

A)micro-size PLC.
B)small-size PLC.
C)medium-size PLC.
D)large-size PLC.

Question 47

The diagram shown is a:

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

Question 48

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

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

Question 49

Block No.6 of the PLC block diagram represents the:

A)processor module.
B)power supply module.
C)input module.
D)output module.

Question 50

The diagram shown is that of a

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

Question 51

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.

Question 52

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.

Question 53

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 54

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.

Question 55

For there to be 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.

Question 56

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 57

Block No.4 of the PLC block diagram represents the:

A)memory.
B)programming device.
C)input module.
D)CPU.

Question 58

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

A)Fixed
B)Modular
C)Digital
D)Analog

Question 59

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