Deck 2: Plc Hardware Components

Question 1

RAM memory is nonvolatile.

Answer 1

False

Question 2

Most PLC programming software will allow you to develop programs on another manufacturer's PLC.

Answer 2

False

Question 3

A nonvolatile memory will retain its programmed contents if operating power is lost.

Answer 3

True

Question 4

Analog signals can have only two states.

Question 5

Information stored in a RAM memory location can be written into or read from.

Question 6

An analog input or output is a signal that varies continuously within a certain range.

Question 7

Optical isolation used in I/O modules helps to reduce the effects of electrical noise.

Question 8

The maximum current rating for the individual outputs of an AC output module is usually in the 20 to 30 ampere range.

Question 9

I/O modules are designed to plug into a slot or connector.

Question 10

The processor may perform functions such as timing,counting,and comparing in addition to logic processing.

Question 11

Electrical noise usually causes permanent operating errors.

Question 12

A thermocouple would be classified as an analog input sensing device.

Question 13

Memory is where the control plan is held or stored in the controller.

Question 14

I/O modules are normally installed or removed while the PLC is powered.

Question 15

Shielded twisted pair cable is used for connecting to thermocouple inputs to reduce unwanted electrical noise.

Question 16

A modular PLC that has room for several I/O modules,is capable of being customized for a particular application.

Question 17

When a new program is loaded into a PLC's memory,the old program that was stored in the same locations is over-written and essentially erased.

Question 18

A volatile memory will lose its programmed contents if operating power is lost.

Question 19

I/O modules are keyed to prevent unauthorized personnel from removing them from the I/O rack.

Question 20

Most input modules have blown fuse indicators.

Question 21

The sum of the backplane current drawn for all modules in a chassis is used to select the appropriate chassis power supply rating.

Question 22

The "ON state input voltage range" specification refers to:

A)the type of voltage device that will be accepted by the input.
B)range of leakage voltage present at the input in its ON state.
C)minimum and maximum output operating voltages.
D)voltage at which the input signal is recognized as being ON.

Question 23

The following statement that does not apply to the optical isolator circuit used in I/O modules is that it:

A)separates high voltage and low voltage circuits.
B)rectifies AC signals.
C)prevents damage caused by line voltage transients.
D)reduces the effect of electrical noise.

Question 24

A/An ____ input or output is a continuously variable signal within a designated range.

A)discrete
B)digital
C)BCD
D)analog

Question 25

If you had a hand-held programming terminal from one manufacturer you can program only that manufacture's PLC using it.

Question 26

Most PLC electronic components are not sensitive to electrostatic discharge.

Question 27

One function of a PLC input interface module is to:

A)accept signals from field devices and convert them into signals that can be used by the processor.
B)convert signals from the processing unit into values that can be used to control the machine or process.
C)input signals from the programming device and convert them into signals that can be used by the CPU.
D)interpret and execute the user program that controls the machine or process.

Question 28

One advantage of discrete relay contact output modules is that they can be used with AC or DC devices.

Question 29

A discrete output interface module is designed to provide:

A)output voltages only in the 5 VDC range.
B)varying AC or DC voltages depending on the type of module selected.
C)ON/OFF switching of the output field device.
D)binary-coded outputs.

Question 30

Which of the following input field devices would most likely be used with an analog interface input module?

A)Pushbutton
B)Limit switch
C)Selector switch
D)Thermocouple

Question 31

The location of a specific input or output field device is identified by the processor by means of its:

A)voltage rating.
B)current rating.
C)wattage rating.
D)address.

Question 32

A ____ is an example of a device that could be used to provide a discrete input to a PLC.

A)pushbutton
B)selector switch
C)limit switch
D)all of these

Question 33

HMI screens are developed using a software package on a PC which is downloaded into the PLC operator interface device.

Question 34

A module inserted into the wrong slot could be damaged.

Question 35

Discrete means that each input or output has two states: true (on)or false (off).

Question 36

Light is used in I/O modules to separate the real-world electrical signals from the PLC internal electronic system.

Question 37

A redundant PLC system is configured using two processors.

Question 38

A ____ is an example of an actuator that could be controlled by a discrete output from a PLC.

A)pushbutton
B)motor starter
C)limit switch
D)all of these

Question 39

Hot swappable I/O modules are designed to be changed with the power on and the PLC operating.

Question 40

Digital modules are also called discrete modules.

Question 41

_____ is a type of memory commonly used for temporary storage of data that may need to be quickly changed.

A)RAM
B)ROM
C)EPROM
D)EEPROM

Question 42

Volatile memory elements can be classified as those that:

A)do not retain stored information when the power is removed.
B)retain stored information when the power is removed.
C)do not require a battery backup.
D)both b and c.

Question 43

Status indicators are provided on each output of an output module to indicate that the:

A)load has been operated.
B)input associated with the output is active.
C)module fuse has blown.
D)output is active.

Question 44

The purpose of the filter section is to:

A)aid in fault diagnosis.
B)set the minimum level of voltage that can be detected.
C)protect against electrical noise interference.
D)separate the higher line voltage from the logic circuits.

Question 45

The I/O system provides an interface between:

A)input modules and output modules.
B)the CPU and field equipment.
C)the CPU and I/O rack.
D)the I/O rack and I/O modules.

Question 46

For the I/O module shown,the arrows point to the:

A)status indicator connections.
B)input connections.
C)output connections.
D)power supply connections.

Question 47

For the block diagram of the output module shown,the input comes from the:

A)input field device.
B)processor.
C)output field device.
D)line power supply.

Question 48

The schematic diagram shown is that of a(n):

A)discrete output module.
B)analog output module.
C)discrete input module.
D)analog input module.

Question 49

The purpose of the LED indicator is to:

A)aid in fault diagnosis.
B)set the minimum level of voltage that can be detected.
C)protect against electrical noise interference.
D)separate the higher line voltage from the logic circuits.

Question 50

The purpose of the zener diode (Z_D)is to:

A)aid in fault diagnosis.
B)set the minimum level of voltage that can be detected.
C)protect against electrical noise interference.
D)separate the higher line voltage from the logic circuits.

Question 51

The most common form of memory used to store,back up,or transfer PLC programs is:

A)RAM
B)Flash EEPROM
C)EEPROM
D)both b and c

Question 52

In event of a power interruption,a(an)_____ is used in some processors to provide power to the RAM.

A)inductor
B)capacitor
C)transistor
D)resistor

Question 53

Which of the following is not a function of a PLC programming device?

A)To enter the user program
B)To change the user program
C)To execute the user program
D)To monitor the user program

Question 54

The Allen-Bradley SLC-500 address I:2/4 refers to an:

A)Input module in slot 4,terminal 2.
B)Output module in slot 4,terminal 2.
C)Input module in slot 2,terminal 4.
D)Output module in slot 2,terminal 4.

Question 55

The Allen-Bradley SLC-500 address O:3/0 refers to an:

A)Input module in slot 3,terminal 0.
B)Output module in slot 3,terminal 0.
C)Input module in slot 0,terminal 3.
D)Output module in slot 0,terminal 3.

Question 56

The schematic diagram shown is that of a(n):

A)discrete output module.
B)analog output module.
C)discrete input module.
D)analog input module.

Question 57

The PLC chassis comes in different sizes according to the:

A)size of the program.
B)type of I/O modules used.
C)number of slots they contain.
D)all of these.

Question 58

For the block diagram of the input module shown,Section #1 represents the ____ and #2 the ____

A)AC,DC.
B)DC,AC.
C)power,logic.
D)logic,power.

Question 59

The purpose of the optical isolator is to:

A)aid in fault diagnosis.
B)set the minimum level of voltage that can be detected.
C)protect against electrical noise interference.
D)separate the higher line voltage from the logic circuits.

Question 60

_____ memory is used by the PLC's operating system.

A)RAM
B)EEPROM
C)Flash
D)ROM

Question 61

High-density I/O modules:

A)may have up to 64 inputs or outputs per module.
B)require more space.
C)can handle greater amounts of current per output.
D)All of these.

Question 62

The current sourcing sensor shown must be matched with a _____ PLC input module.

A)current sinking
B)current sourcing
C)alternating current
D)either a or b

Question 63

Discrete I/O modules can be classified as:

A)bit oriented.
B)word oriented.
C)processor oriented.
D)power supply oriented.

Question 64

For the block diagram of the analog PLC control shown,which part has a binary input and analog output value?

A)Level transmitter
B)Input module
C)Processor
D)Output module

Question 65

For the processor module shown,Block 1 represents the ___ and Block 2 the ___.

A)input,output
B)output,input
C)memory,CPU
D)CPU,memory

Question 66

Which of the following specifications defines the number of field inputs or outputs that can be connected to a single module?

A)Electrical isolation.
B)Points per module.
C)Threshold voltage.
D)Current per input.

Question 67

The input signal to the module comes from:

A)the input field device.
B)the output field device.
C)internal logic circuitry of the processor.
D)either a or b.

Question 68

For the PLC analog I/O control system shown,the fluid flow is controlled by:

A)varying the amount of the valve opening.
B)switching the valve ON and OFF.
C)switching the level sensor ON and OFF.
D)varying the position of the level sensor.

Question 69

When the triac is in the OFF state:

A)zero current always flows through the load.
B)a small leakage current may flow through the load.
C)the rated surge current flows through the lamp.
D)the rated nominal current flows through the lamp.

Question 70

Typical analog inputs and outputs can vary from

A)0 to 20 mA
B)4 to 20 mA
C)0 to 10 volts
D)All of these

Question 71

A ______ module is used to establish connections for the exchange of data.

A)thumbwheel
B)communication
C)servo
D)PID

Question 72

Which of the following special I/O modules would be used to operate a seven-segment LED Display?

A)Encoder-counter module.
B)BCD-output module.
C)Stepper-motor module.
D)High-speed counter module.

Question 73

For the thermocouple analog input module shown,shielded cable is used to:

A)reduce unwanted electrical noise signals.
B)carry the higher current required.
C)lower the resistance of the conductors.
D)insulate the circuit from other cables.

Question 74

The main element of an analog output module is:

A)AC to DC rectifier.
B)DC to AC inverter.
C)analog to digital converter.
D)digital to analog converter.

Question 75

The thermocouple shown is a:

A)ungrounded type with the shield grounded at the module end.
B)ungrounded type with the shield grounded at the thermocouple end.
C)grounded type with the shield grounded at the module end.
D)grounded type with the shield grounded at the thermocouple end.

Question 76

The schematic diagram of Figure 2-6 is an example of how a PLC output module is connected to:

A)isolate the load from the controller.
B)control a high resistance load.
C)vary the speed of a motor.
D)control a high current load.

Question 77

The ____ of an analog I/O module specifies how accurately an analog value can be represented digitally.

A)number of inputs and outputs per card
B)input impedance and capacitance
C)resolution
D)common mode rejection ratio

Question 78

Which of the following devices can be used for switching the output of a discrete DC output module?

A)Transistor.
B)Triac.
C)Relay.
D)either a or c.

Question 79

The purpose of the triac switch is to:

A)turn the load ON and OFF.
B)vary the current flow to the load in accordance with the input signal level.
C)vary the voltage across the load in accordance with the input signal level.
D)both b and c.

Question 80

The processor module of the PLC is where the:

A)ladder logic program is stored.
B)input connections are made.
C)output connections are made.
D)sensors are located.