PLC EXAM QUESTIONS AND ANSWERS
Which of the following is not a suitable application for a PLC? - Answers- To control a
computer numerical control (CNC) machine
PLC are _____ designed for use in the control of a wide variety of manufacturing
machines and systems - Answers- Special-purpose industrial computers
When comparing a relay-based control system to a PLC, which of the following is not an
advantage of the PLC? - Answers- Capable of switching higher output currents
The part of a PLC that executes the logic program is the _____ - Answers- Processor
The purpose of a digital output module is _____ - Answers- To energize loads in
response to PLC instructions
Which of the following is the proper sequence of operation within a PLC? - Answers-
Examine inputs, perform logic, update outputs
Which of the following is how input and output modules communicate with the CPU? -
Answers- By a series of electrical connections in the backplane
Which of the following is the type of PLC memory file used to address hardwired inputs?
- Answers- Input image
Which of the following components does a PLC processor normally not contain? -
Answers- Relay
Which of the following is referred to by the tag name "local"? - Answers- Module
defined
Which of the following is the purpose of the input interface module? - Answers- it
connects the CPU to signals from the process
Which of the following is a consideration for selecting an output module for a PLC? -
Answers- The type of low voltage load driven
Fuse indicator may be located on the _____ - Answers- Output modules
Which of the following modules must be used with a current sourcing sensor? -
Answers- A current sinking input module
Which of the following is the type of load that a triac output module is used to control? -
Answers- To directly control an AC device
, Which of the following is the type of load that a relay output module is used to control? -
Answers- An AC power source
Which of the following does not apply to the optical isolator circuit in the I/O modules? -
Answers- Converting analog signals to digital signals for processing
Which of the following is a common language used to program PLCs that uses a
graphical representation of relay circuits? - Answers- Ladder logic
Which of the following two broad categories are PLC memories divided into? -
Answers- Program and data files
Which of the following type of switching device is used on VDC discrete output
modules? - Answers- A transistor
Which of the following is one advantage to using discrete wiring to connect a PLC to
another control - Answers- The connection can be tested with a simple meter
After connecting a limit switch to the input of a PLC, the proper operation of the switch
can be tested by _____ - Answers- Checking for 24 volts at the ground connection of
the switch
A solenoid is connected to the_____ - Answers- Output terminal of an output module
A newly added electronic sensor doesn't seem to be working properly. Which of the
following is the first thing to check? - Answers- The wiring of the switch
The best way to test the handshake signal provided by the output module of a robot
controller is ____ - Answers- To operate the robot to turn on the output to be tested,
then verifying the PLC input
The best way to test the handshake signal provided by the output module of a PLC to a
robotic controller is ____ - Answers- Cause the PLC output to actuate, and verify that
the signal is present in the robot interface
The main use of input/output diagram is ____ - Answers- To document the physical
connections of the PLC to the machine electrical hardware
Which of the following rules apply when creating an interface diagram between a PLC
and a machine control? - Answers- All connections between PLC and the machine
control must be included
Which of the following best describes serial communication - Answers- The function of
transferring data between two processor-based devices
Which of the following is not a suitable application for a PLC? - Answers- To control a
computer numerical control (CNC) machine
PLC are _____ designed for use in the control of a wide variety of manufacturing
machines and systems - Answers- Special-purpose industrial computers
When comparing a relay-based control system to a PLC, which of the following is not an
advantage of the PLC? - Answers- Capable of switching higher output currents
The part of a PLC that executes the logic program is the _____ - Answers- Processor
The purpose of a digital output module is _____ - Answers- To energize loads in
response to PLC instructions
Which of the following is the proper sequence of operation within a PLC? - Answers-
Examine inputs, perform logic, update outputs
Which of the following is how input and output modules communicate with the CPU? -
Answers- By a series of electrical connections in the backplane
Which of the following is the type of PLC memory file used to address hardwired inputs?
- Answers- Input image
Which of the following components does a PLC processor normally not contain? -
Answers- Relay
Which of the following is referred to by the tag name "local"? - Answers- Module
defined
Which of the following is the purpose of the input interface module? - Answers- it
connects the CPU to signals from the process
Which of the following is a consideration for selecting an output module for a PLC? -
Answers- The type of low voltage load driven
Fuse indicator may be located on the _____ - Answers- Output modules
Which of the following modules must be used with a current sourcing sensor? -
Answers- A current sinking input module
Which of the following is the type of load that a triac output module is used to control? -
Answers- To directly control an AC device
, Which of the following is the type of load that a relay output module is used to control? -
Answers- An AC power source
Which of the following does not apply to the optical isolator circuit in the I/O modules? -
Answers- Converting analog signals to digital signals for processing
Which of the following is a common language used to program PLCs that uses a
graphical representation of relay circuits? - Answers- Ladder logic
Which of the following two broad categories are PLC memories divided into? -
Answers- Program and data files
Which of the following type of switching device is used on VDC discrete output
modules? - Answers- A transistor
Which of the following is one advantage to using discrete wiring to connect a PLC to
another control - Answers- The connection can be tested with a simple meter
After connecting a limit switch to the input of a PLC, the proper operation of the switch
can be tested by _____ - Answers- Checking for 24 volts at the ground connection of
the switch
A solenoid is connected to the_____ - Answers- Output terminal of an output module
A newly added electronic sensor doesn't seem to be working properly. Which of the
following is the first thing to check? - Answers- The wiring of the switch
The best way to test the handshake signal provided by the output module of a robot
controller is ____ - Answers- To operate the robot to turn on the output to be tested,
then verifying the PLC input
The best way to test the handshake signal provided by the output module of a PLC to a
robotic controller is ____ - Answers- Cause the PLC output to actuate, and verify that
the signal is present in the robot interface
The main use of input/output diagram is ____ - Answers- To document the physical
connections of the PLC to the machine electrical hardware
Which of the following rules apply when creating an interface diagram between a PLC
and a machine control? - Answers- All connections between PLC and the machine
control must be included
Which of the following best describes serial communication - Answers- The function of
transferring data between two processor-based devices
