PLC Midterm Test Questions With All Correct
& Verified Answers
What does the PLC power supply do? Correct answer-The power source converts the available
power to a low voltage DC power for the logic circuits of the processor and for the internal power
required for the I/O modules.
Analog I/O devices are either ON or OFF, open or closed Correct answer-False
The I/O section also converts varying voltage or current signals from analog input devices into
corresponding decimal values by way of a(n) Correct answer-Analog to digital converter.
A typical PLC can be divided into three components consisting of the processor unit, the power
supply, and the programming device. Correct answer-False
The term ____________________ is used to distinguish actual devices that exist and must be
physically wired from the internal functions of the PLC system that duplicate the function of relays,
timers, counters, and so on, even though none physically exists. Correct answer-Real World
____________________ is a high-level, real-world, graphic language that is understood by most
electricians and technicians. Correct answer-Relay ladder logic
The reluctance of the end user to learn a new language and the advent of the microprocessor gave
the industry what is now known as the Correct answer-PLC
Even though the electromechanical relay has served well for many generations, the ever-increasing
sophistication and complexity of modern processing equipment requires faster acting, more reliable
control devices than electromechanical relays, timing and/or counting devices can offer. Correct
answer-True
What is a PLC Correct answer-A PLC is a solid state system originally designed to perform logic
functions for the control and operation of manufacturing process equipment and machinery.
Describe when an interface occurs. Correct answer-An interface occurs when two systems come
together and communicate
PLCs are designed to be operated by plant engineers and maintenance personnel with limited
knowledge of computers. Correct answer-True
What determines the size, or power rating of a power supply? Correct answer-The number and
type of I/O modules that will be installed
A(n) ____________________ is used to program most of the PLCs on the market today Correct
answer-laptop
The number of input and output modules necessary is dictated by the requirements of the
equipment that is to be controlled by a PLC. Correct answer-true
List two terms that are used to describe an I/O device Correct answer-Analog and discrete
, Some older PLCs used the ____________________ numbering system for I/O addressing Correct
answer-Octal
Any number that uses an exponent of 0, such as 10E0, has a place value of 10. Correct answer-false
1
The first step in converting 16-bit binary to hexadecimal is to group the 16-bit binary word into
groups of four (conversion to BCD). Correct answer-True
Mathematically, each place value is expressed as a digit number times a power of the base, or 10, in
the decimal numbering system. Correct answer-True
A binary number is always indicated by placing a 2 in subscript to the right of the unit's digit
Correct answer-true
The ____________________ system uses ten unique numbers, or digits, which are 0 through 9
Correct answer-decimal
For systems that operate on ____________________ parity, the parity bit is used to make the total
of 1s add up to an odd number. Correct answer-Odd
How do you convert a negative binary number to the decimal equivalent? Correct answer-First the
negative Binary number is complemented, meaning that 1's are changed to 0 and 0's are changed to
1. Then you must add 1 to the complemented Binary number. You then use the negative Binary
number to convert to a negative Decimal number using the place values. The place values are 1, 2, 4,
and the signed bit has a place value of 8. You multiply the base values by the power of 10 to convert
to Decimal. Once converted to decimal you add a negative sign.
The ASCII code uses different combinations of 8 bit binary (base 2) information for communication of
data. Correct answer-False
Describe even parity. Correct answer-Even parity is where the number of bits with a value of one
are counted. If a number of bits is odd the parity bit is set to 1 to make the total number of 1s in a set
an even number. If a number is even the parity bit is set to 0 to make the total number of 1's in a set
an even number.
The ____________________ system is used when large numbers need to be processed. Correct
answer-Hexadecimal
Describe the hexadecimal system. Correct answer-The Hexadecimal system is a numbering system
with a base of 16. Numbers 0-9 are shown as that digit and numbers 10-15 are shown as letters A-F.
The hexadecimal system is mainly used for processing large numbers. Its similar to other numbering
systems just a different base with letters essentially.
An eighth bit is often used by programmers to provide error checking of information that is
transmitted. This eighth bit is called the ____________________ bit. Correct answer-Parity
What is the BCD system and why was it created? Correct answer-BCD was created to convert large
Decimal numbers into Binary for memory storage. BCD uses 4 binary digits to represent one decimal
digit. BCD has a base of 2 because the digits are Binary. The largest Decimal number that can be
displayed is 9.
& Verified Answers
What does the PLC power supply do? Correct answer-The power source converts the available
power to a low voltage DC power for the logic circuits of the processor and for the internal power
required for the I/O modules.
Analog I/O devices are either ON or OFF, open or closed Correct answer-False
The I/O section also converts varying voltage or current signals from analog input devices into
corresponding decimal values by way of a(n) Correct answer-Analog to digital converter.
A typical PLC can be divided into three components consisting of the processor unit, the power
supply, and the programming device. Correct answer-False
The term ____________________ is used to distinguish actual devices that exist and must be
physically wired from the internal functions of the PLC system that duplicate the function of relays,
timers, counters, and so on, even though none physically exists. Correct answer-Real World
____________________ is a high-level, real-world, graphic language that is understood by most
electricians and technicians. Correct answer-Relay ladder logic
The reluctance of the end user to learn a new language and the advent of the microprocessor gave
the industry what is now known as the Correct answer-PLC
Even though the electromechanical relay has served well for many generations, the ever-increasing
sophistication and complexity of modern processing equipment requires faster acting, more reliable
control devices than electromechanical relays, timing and/or counting devices can offer. Correct
answer-True
What is a PLC Correct answer-A PLC is a solid state system originally designed to perform logic
functions for the control and operation of manufacturing process equipment and machinery.
Describe when an interface occurs. Correct answer-An interface occurs when two systems come
together and communicate
PLCs are designed to be operated by plant engineers and maintenance personnel with limited
knowledge of computers. Correct answer-True
What determines the size, or power rating of a power supply? Correct answer-The number and
type of I/O modules that will be installed
A(n) ____________________ is used to program most of the PLCs on the market today Correct
answer-laptop
The number of input and output modules necessary is dictated by the requirements of the
equipment that is to be controlled by a PLC. Correct answer-true
List two terms that are used to describe an I/O device Correct answer-Analog and discrete
, Some older PLCs used the ____________________ numbering system for I/O addressing Correct
answer-Octal
Any number that uses an exponent of 0, such as 10E0, has a place value of 10. Correct answer-false
1
The first step in converting 16-bit binary to hexadecimal is to group the 16-bit binary word into
groups of four (conversion to BCD). Correct answer-True
Mathematically, each place value is expressed as a digit number times a power of the base, or 10, in
the decimal numbering system. Correct answer-True
A binary number is always indicated by placing a 2 in subscript to the right of the unit's digit
Correct answer-true
The ____________________ system uses ten unique numbers, or digits, which are 0 through 9
Correct answer-decimal
For systems that operate on ____________________ parity, the parity bit is used to make the total
of 1s add up to an odd number. Correct answer-Odd
How do you convert a negative binary number to the decimal equivalent? Correct answer-First the
negative Binary number is complemented, meaning that 1's are changed to 0 and 0's are changed to
1. Then you must add 1 to the complemented Binary number. You then use the negative Binary
number to convert to a negative Decimal number using the place values. The place values are 1, 2, 4,
and the signed bit has a place value of 8. You multiply the base values by the power of 10 to convert
to Decimal. Once converted to decimal you add a negative sign.
The ASCII code uses different combinations of 8 bit binary (base 2) information for communication of
data. Correct answer-False
Describe even parity. Correct answer-Even parity is where the number of bits with a value of one
are counted. If a number of bits is odd the parity bit is set to 1 to make the total number of 1s in a set
an even number. If a number is even the parity bit is set to 0 to make the total number of 1's in a set
an even number.
The ____________________ system is used when large numbers need to be processed. Correct
answer-Hexadecimal
Describe the hexadecimal system. Correct answer-The Hexadecimal system is a numbering system
with a base of 16. Numbers 0-9 are shown as that digit and numbers 10-15 are shown as letters A-F.
The hexadecimal system is mainly used for processing large numbers. Its similar to other numbering
systems just a different base with letters essentially.
An eighth bit is often used by programmers to provide error checking of information that is
transmitted. This eighth bit is called the ____________________ bit. Correct answer-Parity
What is the BCD system and why was it created? Correct answer-BCD was created to convert large
Decimal numbers into Binary for memory storage. BCD uses 4 binary digits to represent one decimal
digit. BCD has a base of 2 because the digits are Binary. The largest Decimal number that can be
displayed is 9.
