PLC Exam Questions With All Correct &
Verified Answers
What are the major parts of a plc? Correct answer-The CPU, I/O, power supply, and programming
device
Architecture Correct answer-Refers to PLC hardware or software
Open architecture Correct answer-Allows the system to be connected easily to devices and
programs made by other manufacturers
Closed architecture Correct answer-A system whose design is proprietary making it difficult to
connect to other systems
Fixed I/O Correct answer-Small PLC that comes in one package with not separate removable units.
The processor and I/O are packaged together
Modular I/O Correct answer-A PLC that is divided by compartments into which separate modules
can be plugged
Power supply Correct answer-Provides DC power to all modules that plug into the rack
CPU or processor Correct answer-A microprocessor for implementing the logic and controlling the
communications among the modules
PLC scan cycle Correct answer-Reads inputs -> executes program -> diagnostics & communication -
> updates outputs
I/O (Input/Output) system Correct answer-Forms the interface by which field devices are
connected to the controller.
I/O (Input/Output) system Correct answer-Forms the interface by which field devices are
connected to the controller
Programming device Correct answer-Used to enter the desired program into the memory of the
processor
Personal computer (PC) Correct answer-The most commonly used programming device
Program Correct answer-A series of instructions that directs the PLC to execute actions
Relay ladder logic Correct answer-The standard programming language, is based on
electromagnetic relay control
Address Correct answer-Where an input or output device is conncected
PC vs PLC Correct answer-PLC is designed to operate in the industrial environment with wide
ranges of ambient temperature and humidity
, Human machine interface (HMI) Correct answer-Software that allows the user to monitor and
control the process
Programmable Automation Controllers (PACs) Correct answer-Combine PLC ruggedness with PC
functionality
Nano Correct answer-Smallest size with less than 15 I/O
Micro Correct answer-15-128 I/O
Medium Correct answer-128-512 I/O
Large Correct answer-Over 512 I/O
Single ended application Correct answer-One PLC controlling one process
Multitask application Correct answer-One PLC controlling several processes
Control management application Correct answer-One PLC controlling several others
Memory Correct answer-Part of a PLC controller that stores data, instructions, and the control
program
Memory size Correct answer-Expressed in K values
1K = Correct answer-1024
Amount of memory required depends on Correct answer-• Number of I/O points
used
• Size of control
program
• Data-collecting
requirements
• Supervisory functions
required
• Future expansion
Input interface modules Correct answer-accept signals from the
machine or process devices and convert them into
signals that can be used by the controller
Output interface modules Correct answer-convert controller signals
into external signals used to control the machine or
process
chassis Correct answer-hardware assembly that houses I/O modules,
processor modules, and power supplies
logical rack Correct answer-an addressable unit consisting of 128
input points and 128 output points
Verified Answers
What are the major parts of a plc? Correct answer-The CPU, I/O, power supply, and programming
device
Architecture Correct answer-Refers to PLC hardware or software
Open architecture Correct answer-Allows the system to be connected easily to devices and
programs made by other manufacturers
Closed architecture Correct answer-A system whose design is proprietary making it difficult to
connect to other systems
Fixed I/O Correct answer-Small PLC that comes in one package with not separate removable units.
The processor and I/O are packaged together
Modular I/O Correct answer-A PLC that is divided by compartments into which separate modules
can be plugged
Power supply Correct answer-Provides DC power to all modules that plug into the rack
CPU or processor Correct answer-A microprocessor for implementing the logic and controlling the
communications among the modules
PLC scan cycle Correct answer-Reads inputs -> executes program -> diagnostics & communication -
> updates outputs
I/O (Input/Output) system Correct answer-Forms the interface by which field devices are
connected to the controller.
I/O (Input/Output) system Correct answer-Forms the interface by which field devices are
connected to the controller
Programming device Correct answer-Used to enter the desired program into the memory of the
processor
Personal computer (PC) Correct answer-The most commonly used programming device
Program Correct answer-A series of instructions that directs the PLC to execute actions
Relay ladder logic Correct answer-The standard programming language, is based on
electromagnetic relay control
Address Correct answer-Where an input or output device is conncected
PC vs PLC Correct answer-PLC is designed to operate in the industrial environment with wide
ranges of ambient temperature and humidity
, Human machine interface (HMI) Correct answer-Software that allows the user to monitor and
control the process
Programmable Automation Controllers (PACs) Correct answer-Combine PLC ruggedness with PC
functionality
Nano Correct answer-Smallest size with less than 15 I/O
Micro Correct answer-15-128 I/O
Medium Correct answer-128-512 I/O
Large Correct answer-Over 512 I/O
Single ended application Correct answer-One PLC controlling one process
Multitask application Correct answer-One PLC controlling several processes
Control management application Correct answer-One PLC controlling several others
Memory Correct answer-Part of a PLC controller that stores data, instructions, and the control
program
Memory size Correct answer-Expressed in K values
1K = Correct answer-1024
Amount of memory required depends on Correct answer-• Number of I/O points
used
• Size of control
program
• Data-collecting
requirements
• Supervisory functions
required
• Future expansion
Input interface modules Correct answer-accept signals from the
machine or process devices and convert them into
signals that can be used by the controller
Output interface modules Correct answer-convert controller signals
into external signals used to control the machine or
process
chassis Correct answer-hardware assembly that houses I/O modules,
processor modules, and power supplies
logical rack Correct answer-an addressable unit consisting of 128
input points and 128 output points
