PLC: Final Exam Ch. 1 Test Questions
with Correct/Verified Answers 2026-
2027 Updated.
Programmable logic controllers - Answer An industrial grade computer that is capable of
being programmed to perform control functions.
Easy programming and installation, high control speed, network compatibility, troubleshooting
and testing convenience and high reliability. - Answer What are some PLC benefits?
Traditional relay logic that includes wiring - Answer What do PLCs replace?
Fixed I/O - Answer Typical of small PLC's that come in one package with no separate,
removable units. Processor and I/O units are packaged together. I/O terminals are specific
number of connections.
Yes, by buying additional units of fixed I/O. - Answer Can Fixed I/O be expanded
Advantage of fixed I/O - Answer Lower cost
lack of flexibility. If any part of the unit fails, the whole unit has to be replaced. - Answer
What are some Fixed I/O disadvantages?
Modular I/O - Answer I/O divided into compartments into which separate modules can be
plugged. Greatly increases flexibility. You can choose from the modules available from the
manufacture and mix how you desire.
Parts of Modular Controller - Answer Rack, power supply, processor unit, I/O, and operator
interface for programming and monitoring.
Backplane - Answer Where the module slides into the rack making an electrical contact.
Power Supply - Answer Supplies DC power to other modules that plug into the rack.
Power supply of Large PLC's - Answer Regular power supply is insufficient. Provided by
external AC or DC supplies
, Processor - Answer AKA CPU. Consists of microprocessors to implement the logic and
controlling the commo among the modules. Requires memory
Central Processing Unit - Answer What is the Brain of a PLC?
Scan - Answer Repetitive process that a PLC program uses.
1. Read Inputs
2. Execute program
3. Diagnostics and communication
4. Update outputs
Input Device Examples - Answer Pushbuttons, limit switches, sensors
Output Device Examples - Answer Small motors, motor starters, solenoid valves, indicator
lights.
Optical Isolator - Answer Light which couples circuits together to electrically isolate the
internal components from the input and output terminals.
Field/ Real World Devices - Answer Actual external devices that exist and must be physically
wired from the internal user program that duplicates the function of relays, timers and
counters.
Programming Device - Answer Used to enter the desired program into the memory of the
processor.
Relay Ladder Logic - Answer One of the more popular programming languages. Uses graphic
symbols that show intended outcome rather than words
Programming Devices - Answer Handheld device because they are inexpensive and easy to
use.
PC - Answer Most common Programming device
Software is compatible, monitors can display more logic on the screen - Answer What is
necessary for a PC to be used as a PLC and how is it beneficial?
No - Answer Will removing the programming unit affect operation
with Correct/Verified Answers 2026-
2027 Updated.
Programmable logic controllers - Answer An industrial grade computer that is capable of
being programmed to perform control functions.
Easy programming and installation, high control speed, network compatibility, troubleshooting
and testing convenience and high reliability. - Answer What are some PLC benefits?
Traditional relay logic that includes wiring - Answer What do PLCs replace?
Fixed I/O - Answer Typical of small PLC's that come in one package with no separate,
removable units. Processor and I/O units are packaged together. I/O terminals are specific
number of connections.
Yes, by buying additional units of fixed I/O. - Answer Can Fixed I/O be expanded
Advantage of fixed I/O - Answer Lower cost
lack of flexibility. If any part of the unit fails, the whole unit has to be replaced. - Answer
What are some Fixed I/O disadvantages?
Modular I/O - Answer I/O divided into compartments into which separate modules can be
plugged. Greatly increases flexibility. You can choose from the modules available from the
manufacture and mix how you desire.
Parts of Modular Controller - Answer Rack, power supply, processor unit, I/O, and operator
interface for programming and monitoring.
Backplane - Answer Where the module slides into the rack making an electrical contact.
Power Supply - Answer Supplies DC power to other modules that plug into the rack.
Power supply of Large PLC's - Answer Regular power supply is insufficient. Provided by
external AC or DC supplies
, Processor - Answer AKA CPU. Consists of microprocessors to implement the logic and
controlling the commo among the modules. Requires memory
Central Processing Unit - Answer What is the Brain of a PLC?
Scan - Answer Repetitive process that a PLC program uses.
1. Read Inputs
2. Execute program
3. Diagnostics and communication
4. Update outputs
Input Device Examples - Answer Pushbuttons, limit switches, sensors
Output Device Examples - Answer Small motors, motor starters, solenoid valves, indicator
lights.
Optical Isolator - Answer Light which couples circuits together to electrically isolate the
internal components from the input and output terminals.
Field/ Real World Devices - Answer Actual external devices that exist and must be physically
wired from the internal user program that duplicates the function of relays, timers and
counters.
Programming Device - Answer Used to enter the desired program into the memory of the
processor.
Relay Ladder Logic - Answer One of the more popular programming languages. Uses graphic
symbols that show intended outcome rather than words
Programming Devices - Answer Handheld device because they are inexpensive and easy to
use.
PC - Answer Most common Programming device
Software is compatible, monitors can display more logic on the screen - Answer What is
necessary for a PC to be used as a PLC and how is it beneficial?
No - Answer Will removing the programming unit affect operation
