Plc test 1

To express a number in binary requires fewer digits than in the decimal system. True or false

True

Usually a group of 8 bits is a byte, and a group of one or more bytes is a word. True or false

True

When a new program is loaded into a PLCs memory, the old program that was stored in the same location is over written and essentially erased. True or false

True

The basic rule for an AND gate is ? A.) if all inputs are 1, the output will be 1 B.) if all inputs are 1, the output will be 0 C.) if all inputs are 0, the output will be 1 D.) if all inputs are 1, the output will be 1 and 0

A.) if all inputs are 1, the output will be 1

The decimal number 213 would be written in BCD as: A.) 0010 0001 0011 B.) 1101 1000 1100 C.) 0111 1001 0011 D.) 1011 1101 0101

A.) 0010 0001 0011

Block No. 3 of the PLC block diagram represents the

A.) CPU unit

The logic symbol drawn is that of the ? A.) NOT function B.) NOR function C.) NAND function D.) OR function

A.) NOT function

A single rung of a ladder logic program is arranged with: A.) input conditions connected from left to right, with the output at the far right. B.) input conditions connected from right to left, with the outputs at the far left. C.) the output in the center and the input conditions to the left and right of it. D.) all input conditions in parallel and all output conditions in series.

A.) input conditions connected from left to right, with output at the far right.

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

A.) number of I/O points

The main advantage of using Gray code is? A.) only one digit changes as the number increases B.) it can be easily converted to decimal numbers. C.) large decimal numbers can be written using fewer digits D.) or uses the number 2 as its base

A.) only one digit changes as the number increases

An ______ bit is used to detect errors that may occur while a word is moved A.) parity B.) negative C.) positive D.) overflow

A.) parity

The most commonly used programming device is a A.) personal computer B.) dedicated industrial programming terminal C.) hand held programmer D.) proprietary programming device

A.) personal computer

When placed in the ______ mode, the processor does not scan/execute the ladder program. A.) program B.) run C.) test D.) remote

A.) program

Values of important process variables over a period of time are shown by an _______ display A.) trend B.) event history C.) alarm D.) all of these choices are correct

A.) trend

The Boolean expression for the logic circuit drawn is ?

AB+C

The logic functions used by PLCs is A.) AND B.) OR C.) NOT D.) All of these are correct

All of these are correct

In conventional logic circuits, binary 1 represents ? A.) the presence of a signal B.) the occurrence of some event C.) a high voltage level D.) All of these choices are correct.

All of these chocies are correct

Which of the hardwired relay schematics is being implemented by the PLC program shown?

B

An ______ defines a memory location where data are stored A.) analog-tag B.) base-tag C.) digital-tag D.) alias-tag

B.) base-tag

In the event of a power interruption an _____ is used in some processors to provide power to the RAM A.) inductor B.) capacitor C.) transistor D.) resistor

B.) capacitor

Which module of the PLC is responsible for performing logical operations? A.) processor B.) input C.) output D.) power supply

B.) input

The diagram shown is that of an ?

B.) ladder logic program

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

B.) output

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

B.) points per module

A discrete output interface module is designed to provide A.) output voltage 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

C.) ON/OFF switching of the output field device

All digit computing devices operate using the binary number system because: A.) most people are familiar with it B.) large decimal numbers can be represented in a shorter form C.) digital circuits can be easily distinguished between two voltage levels D.) All of these choices are correct

C.) digital circuits can be easily distinguished between two voltage levels

For the processor module shown, Block 1 represents the _______ and Block 2 the ______

C.) memory, CPU

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

C.) to execute the user program

The hexadecimal number C4 would be written in decimal as A.) 21 B.) 48 C.) 182 D.) 196

D.) 196

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

D.) PLC backplane and I/O modules

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

D.) address

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 choices are correct

D.) all of these choices are correct

The NOT function can be thought of as A.) a FALSE-to-TRUE converter B.) a changer of states C.) an inverter D.) All of these choices are correct

D.) all of these choices are correct

Which of the following would be classified as engineering units? A.) Degrees Fahrenheit B.) Centimeter C.) pounds per square inch D.) all of these choices are correct

D.) all of these choices are correct

The number 127 could not be ? A.) decimal B.) hexadecimal C.) octal D.) binary

D.) binary

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 input signal level D.) both vary the current flow to the load in accordance with the input signal level and vary the voltage across the load in accordance with the input signal level.

D.) both vary the current flow to the load in accordance with the input signal level and vary the voltage across the load in accordance with the input signal level.

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

D.) both when entering a program and when monitoring a program

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

D.) digital to analog converter

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

D.) output module

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

D.) voltage at which the input signal is recognized as being ON

A two input OR function, expressed as a Boolean equation would be y= AB. true or false

False

All PLCs have input and output interfaces and a memory capability. True or false

False

All inputs to a NAND gate must be 1 to produce a 1 output. True or false

False

Analog signals can have only two states. True or false

False

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

False

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

False

PLCs have sporadic reliability. True or false

False

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

False

There is no difference between a relay schematic and a ladder logic program. True or false

False

All inputs to a NOR gate must be 1 to produce a 1 output. True or false

False If they are 0 they are 1

The AND function, implemented using switches, will mean switches connected in parallel. True or false

False they are in a series

The truth table for the logic symbol is ?

It's a NAND So the answer is B

The logic symbol shown A.) AND function B.) OR function C.) NOT function D.) NAND function

OR function

The OR function, implemented using contacts, requires contracts in. A.) series B.) parallel C.) series/parallel D.) parallel/series

Parallel

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

True

A programming terminal must be connected to the PLC at all times ? True or False

True

A redundant PLC system is configured using two processors. True or false

True

A volatile memory will lose its programmed contents of operating power is lost. True of false

True

All number systems use position weighting to represent the significance of an individual digit in a group of numbers. True or false

True

Decimal floating point numbers usually take the form of scientific notation. True or false

True

Decimal values entered into a digital machine must be converted into binary form. True or false

True

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

True

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

True

If you had a hand held programming terminal from one manufacturer you can program only that manufactures PLC using it. True or false

True

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

True

Programmable control is based on logic functions that are programmable and easily changed. True or false

True

Scaling refers to the changing of a quantity from one notation to another. True of false

True

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

True

The + symbol is used to express the OR function in Boolean algebra. True or false

True

The OR gate is essentially a parallel circuit that produces an output voltage when a voltage appears at any input. True of false

True

The digit of a binary number that has the lowest weight is called the least significant. True or false

True

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

True

The number and type of I/O cannot be changed in a fixed PLC. true or false

True

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

True

The Boolean equation for the logic symbol is ?

Y= A not Answer is D