Intro to PLCs Exam I

The octal number 153 would be written in binary as:

001 101 011.

The decimal number 213 would be written in BCD as:

0010 0001 0011.

The hexadecimal number 2D9 would be written in binary as:

0010 1101 1001

The 2's complement form of a binary number is the binary number that results when: a.) all the 1's are changed to 0's. b.) all the 0's are changed to 1's. c.) 1 is added to the 1's complement. d.) both a and b

1 is added to the 1's complement

The 2's complement form of a binary number is the binary number that results when:

1 is added to the 1's complement.

The decimal system has as its base:

10

the decimal system has as its base

10

A memory that has a capacity of 700 sixteen-bit words can actually store __ bits of information.

11,200

The truth table for the logic symbol is:

1110

The decimal number 28 would be written in binary as:

11100.

The decimal number 15 would be written in binary as:

1111

The number 12 is:

12 in decimal

the number 12 is: a.) 12 in any number system. b.) 12 in decimal. c.) 12 in binary. d.) all of the above.

12 in decimal

The hexadecimal number C4 would be written in decimal as:

196

If a given memory unit consists of 1250 16-bit words, the memory capacity would be rated: a) 1250 bits b) 20,000 bits c) 3260 bits d) 156 bits

20,000 bits

If a given memory unit consists of 1250 16-bit words, the memory capacity would be rated:

20,000 bits.

The binary number 101101 would be written in decimal as:

45

The binary number 101 has the decimal equivalent of:

5

The octal number 62 would be written in decimal as:

50

For a base 8 number system, the weight value associated with the third digit would be:

64

for base 8 number system, the weight value associated with the 3rd digit would be: 16. 32. 64. 512.

64 (8^2)

If you want to know when one or both matching bits in two different words are ON, you would use the logic instruction.

OR

One function of a PLC input interface module is to

accept signals from field devices and convert them into signals that can be used by the processor

In conventional logic circuits, binary 1 represents:

all of these

The NOT function can be thought of as:

all of these

The logic function(s) used by PI-Cs is (are):

all of these

A NOR gate is:

an OR gate with an inverter connected to the output.

PLCs work on_____ numbers in one form or another to represent various code quantities

binary

The number 127 could not be:

binary

the number 127 could not be: a.) decimal. b.) hexadecimal. c.) octal. d.) binary.

binary

The acronym BCD stands for:

binary-coded decimal.

Each digit of a binary number is called a?

bit

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

both Flash EEPROM and EEPROM.

The binary concept makes use of the fact that certain informal

can exist in one of two possible states.

A NOT function is used when a logic 1 must some device.

deactivate

All digital computing devices operate using the binary number system because:

digital circuits can be easily distinguished between two voltage levels

All digital 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 the above.

digital circuits can be easily distinguished between two voltage levels

The schematic diagram shown is that of a(n)

discrete input module.

Two systems of parity are normally used: (a) ____and (b) ___ .

even and odd?

t/f: binary number systems use positive and negative symbols to represent the polarity of a number

false

t/f: the decimal system uses the number 9 at its base

false

t/f: to express a number in binary requires fewer digits than in the decimal system

false

The basic rule for an AND gate is:

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

The basic rule for an XOR function is:

if one or more inputs are 0, the output is 1.

The basic rule for an OR gate is:

if one or more inputs are 1, the output is 1.

ASCII code: 1.) is used with absolute encoders. 2.) is considered to be an error-minimizing code. 3.) includes letters as well as numbers. 4.) all of the above.

includes letters as well as numbers

The ASCII code:

includes letters as well as numbers.

A single rung of a ladder logic program is arranged with:

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

in the sign but position, a 1 indicated a(n): a.) negative number. b.) positive number. c.) octal code. d.) hexadecimal code.

negative number

In the sign bit position, a 1 indicates a(n):

negative number.

the main advantage of using the gray code is

only one digit changes as the number increases

The main advantage of using the Gray code is:

only one digit changes as the number increases.

The OR function, implemented using contacts, requires contacts connected in:

parallel

A(n) bit is used to detect errors that may occur while a word is moved.

parity

a ___ bit is used to detect errors that may occur while a word is moved

parity

A gate is a device that:

performs a logical decision based on its inputs.

The most commonly used programming device is a

personal computer.

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

power, logic

In any number system, the position of a digit that represents part of the number has a "weight" associated with its value. The place weights for binary:

start with 1 and are successive powers of 2

In any number system, the position of a digit that represents part of the number has a "weight" associated with its value. The place weights for binary: a.) start with 1 and are successive powers of 2. b.) increase by adding 2 for each place, starting with 0. c.) increase by adding 2 for each place, starting with 2. d.) start with 2 and double for each successive place.

start with 1 and are successive powers of 2

t/f the radix of a number system is the same as the bse

true

t/f: The base of a number system determines the total number of unique symbols used by that system.

true

t/f: The hexadecimal number system consists of 16 digits including the numbers 0 through 9 and letters A through F.

true

t/f: The octal number system consists of digits 0, 1, 2, 3, 4, 5, 6, and 7. There are no 8's or 9's.

true

t/f: all digital computing devices perform operations in binary

true

t/f: in any number system, the position of a digit that represents part if the number has a weighted value associated with it

true

t/f: in the gray code there is a max of one nit change between two consecutive numbers

true

t/f: usually a group of 8 bits is a byte, and a group of or more bytes is a word

true

The "ON state input voltage range" specification refers to

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

Which of the following number systems has a base of 16?

Hexadecimal

A two input OR function, expressed as a Boolean equation, would be Y= AB.

False

All gates are devices that have one input with which they perform logic decisions and produce a result at one or more of their outputs.

False

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

False

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

False

Binary number systems use positive and negative symbols to represent the polarity of a number.

False

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

False

The decimal system uses the number 9 as its base.

False

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

False

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

False

All digital computing devices perform operations in binary.

True

All inputs to an AND gate must be 1 to produce a 1 output.

True

Hardwired logic can be implemented using relays and relay schematics

True

Hardwired logic is fixed and is changeable only by altering the way devices are connected.

True

Hardwired logic refers to logic control functions determined by the way devices are interconnected.

True

In any number system, the position of a digit that represents part of the number has a weighted value associated with it.

True

In the Gray code there is a maximum of one bit change between two consecutive numbers.

True

Inverting the output of an OR gate will result in creating a NOR gate.

True

Ladder logic is a graphical representation of a user program.

True

Normally, a binary 1 represents the presence of a signal, while a binary 0 represents the absence of a signal.

True

On some PLCs, only one output is allowed per ladder logic rung.

True

One of the most common PLC programming languages is ladder logic.

True

Only one input to an OR gate must be 1 to produce a 1 output.

True

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

True

The base of a number system determines the total number of unique symbols used by that system.

True

The hexadecimal number system consists of 16 digits including the numbers 0 through 9 and letters A through F.

True

The octal number system consists of digits 0, 1, 2, 3, 4, 5, 6, and 7. There are no 8's or 9's.

True

The radix of a number system is the same as the base.

True

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

True

A OR gate operates on the same principle as:

a parallel circuit.

An AND gate operates on the same principle as:

a series circuit.