#4 Top 50 PLC and SCADA MCQ

Important 50 Multiple Choice Question based on PLC and SCADA


Question 1: What is the full form of SCADA?

  • Supervisory Control and Document Acquisition
  • Supervisory Control and Data Acquisition
  • Supervisory Column and Data Assessment
  • Supervisory Column and Data Assessment

Answer: Supervisory Control and Data Acquisition

Question 2: DCS is a ______

  • Distributed Control System
  • Data Control System
  • Data Column System
  • Distributed Column System

Answer: Distributed Control System

Question 3 The control in SCADA is _____________

  • Online control
  • Direct control
  • Supervisory control
  • Automatic control

Answer: Supervisory control

Question 4 What is SCADA?

  • Software
  • Process
  • System
  • Hardware

Answer: Process

Question 5 Which of the following is not the component of a SCADA system?

  • Database server
  • I/O system
  • PLC controller
  • Sparger controller

Answer: Sparger controller

Question 6 When did the SCADA start?

  • 1980s
  • 1990s
  • 1970s
  • 1960s

Answer:1960s

Question 7 When did Windows become the world standard operating system?

  • 1980s
  • 1990s
  • 1970s
  • 1960s

Answer: 1990s

Question 8 How many levels are present in a complex SCADA system?

  • 3 – levels
  • 5 – levels
  • 4 – levels
  • 6 – levels

Answer: 4 – levels

Question 9 What is the full form of RAID

  • Redundant Array of Independent Drives
  • Redundant Array of Inexpensive Disks
  • Redundant Array of Independent Disks
  • All of the above

Answer: All of the above

Question 10 Which of the following is used for centralized network databases?

  • RAID 2
  • RAID 5
  • RAID 1
  • RAID 2

Answer: RAID 5

Question 11 Which of the following is the heart of a SCADA system?

  • PLC
  • HMI
  • Alarm task
  • I/O task

Answer: I/O task

Question 12 Which of the following is an example of the SCADA system?

  • Emerson Delta V
  • Honeywell Plant Scape
  • Yokogawa CENTUM
  • Power Studio Deluxe

Answer: Power Studio Deluxe

Question 13 What does NC stands for?

  • New Configuration
  • Normally Close
  • Normal Classes
  • Never Closing

Answer: Normally Close

Question 14 What is nominal DC voltage given to PLC?

  • +10V
  • +24V
  • +5V
  • +12V

Answer: +5V

Question 15 In which of the following is a PLC Programming tool.

  • RS Logix 500
  • RS view 32
  • Keil u vision
  • Core Vision AVR

Answer: RS Logix 500

Question 16 Among following which one is a PLC Programming Language

  • Assembly
  • Ladder Logic
  • Java
  • HTML

Answer: Ladder Logic

Question 17 In which of the following is the SCADA Software?

  • OrCAD
  • RS View32
  • Keil u vision
  • Porteous

Answer: RS View32

Question 18 Ladder logic programming consists primarily of:

  • Virtual relay contacts and coils
  • Logic gate symbols with connecting lines
  • Function blocks with connecting lines
  • Text-based code
  • Hieroglyphics

Answer: Virtual relay contacts and coils

Question 19 Examine-on instruction in PLC language is symbolically represented by what shape?

  • -] [-
  • -( )-
  • -]/[-
  • None of these

Answer: -] [-

Question 20 The symbol -(L)- represent what instruction in the PLC language?

  • OUT output unlatch instruction.
  • OTL output latch instruction
  • Examine off instruction.
  • Output energize instruction

Answer: OTL output latch instruction

Question 21 In a PLC, the scan time refers to the amount of time in which …..

  • The technician enters the program
  • Timers and counters are indexed by
  • One “rung” of ladder logic takes to complete
  • The entire program takes to execute
  • Transmitted data communications must finish

Answer: The entire program takes to execute

Question 22 The Boolean representation of this PLC program is:

  • ABC + D
  • C + (A + B)D
  • C + D(A + B)
  • ABC + BD
  • C(AB + D)

Answer: C(AB + D)

Question 23 What is the color used for NO type switches?

  • Red
  • Green
  • non of the above

Answer: non of the above

Question 24 To reset the time for a PLC what condition must be true?

  • Reset rung of TON must be true.
  • Reset rung of TON must be false.
  • RST instruction with timer address must be true.
  • RST instruction with associated timer address must be false

Answer: RST instruction with timer address must be true.

Question 25 The below rung would represent what Boolean equation?

  • X • Y = Z
  • X + Y = Z
  • X • Y’ = Z
  • None of the above.

Answer: X • Y’ = Z

Question 26 To increase the number of inputs and outputs of the PLC, one can use expansion modules.

  • True.
  • False.
  • None of the above.

Answer: True.

Question 27 Solenoids, lamps, motors are connected to:

  • Analog output.
  • Digital output.
  • Analog input.
  • Digital input

Answer: Digital output.

Question 28 The _____ is moved toward the relay electromagnet when the relay is on.

  • Armature
  • Coil
  • NO contact
  • NC contact

Answer: Armature

Question 29 In a current sinking DC input module _____

  • The current flows out of the input field device
  • Requires that a AC sources be used with mechanical switches
  • The current flows out of the input module
  • Currents can flow in either direction at the input module

Answer: The current flows out of the input field device

Question 30 AC output field devices can interface to _____

  • AC output modules
  • Relay output modules
  • Both a and b
  • Neither a or b

Answer: Both a and b

Question 31 The difference between online and offline PLC programming is . . .

  • Whether the PLC is running or stopped
  • Whether the programming PC has internet connectivity
  • The type of programming cable used
  • Where the edited program resides
  • The type of programmer used

Answer: Where the edited program resides

Question 32 In PLC programming, a retentive function is one that:

  • Defaults to the “on” state
  • Comes last in the program
  • Defaults to the “off” state
  • Cannot be edited or deleted
  • Is not reset after a power cycle

Answer: Is not reset after a power cycle

Question 33 Normally open contacts are open when:

  • When Input is not energized
  • When the input is energized
  • When input is higher than 20 volts
  • None of these

Answer: When Input is not energized

Question 34 What is the largest integer number that a PLC counter function can reach if it uses a 16 bit register?

  • 32,768
  • 65,535
  • 65,536
  • 65,537
  • 32,767

Answer: 65,535

Question 35 An NOR function implemented in ladder logic uses:

  • Normally-closed contacts in series
  • Normally-open contacts in series
  • A single normally-closed contact
  • Normally-open contacts in parallel
  • Normally-closed contacts in parallel

Answer: Normally-closed contacts in series

Question 36 Which of the following instruction enables a jump to a subroutine?

  • JMP
  • SBR
  • RET
  • None of the above

Answer: JMP

Question 37 What are the features of SCADA?

  • Control feature using a graphical representation
  • Alarm Handling
  • Security Management
  • All of the above

Answer: All of the above

Question 38 Leading SCADA providers companies are.

  • Siemens WinCC
  • Microsoft
  • TCS
  • All of the above

Answer: Siemens WinCC

Question 39 What is Scripts in SCADA?

  • Scripts are basically a form
  • Scripts are basically a function
  • Scripts are basically a facility
  • Scripts are basically a favorite

Answer: Scripts are basically a function

Question 40 What is CIMPLICITY?

  • SCADA package
  • SCADA hardware
  • SCADA software
  • SCADA handler

Answer: SCADA package

Question 41 A good application for a timed interrupt in a PLC program would be:

  • A communications function block
  • A PID function block
  • A math function block
  • A motor start/stop rung
  • A “watchdog” timer

Answer: A PID function block

Question 42 What is the full form of RTU ?

  • Remote Terminate Unit
  • Remote Terminal Unit
  • Remote Translation Unit
  • Remote Transfer Unit

Answer: Remote Terminal Unit

Question 43 What is the full form DDE?

  • Dynamic Data Exchange
  • Data Dynamic Exchange
  • Domain Data Exchange
  • Different Data Exchange

Answer: Dynamic Data Exchange

Question 44 What is the difference between SCADA and HMI.

  • Both are same
  • HMI is not related with SCADA
  • HMI can be a part of SCADA but SCADA can’t be a part of HMI.
  • SCADA is a part of HMI

Answer: HMI can be a part of SCADA but SCADA can’t be a part of HMI.

Question 45 What are the differences between PLC and SCADA?

  • PLC is a hardware part while SCADA is a software part.
  • PLC is a  software  part while SCADA is a hardware part.
  • Both are hardware unit
  • Both are software

Answer: PLC is a hardware part while SCADA is a software part.

Question 46 A PLC consists of

  • Processor Unit
  • Program Memory
  • Input/output Section
  • Display Device
  • All of the above

Answer: All of the above

Question 47 An OR function implemented in ladder logic uses:

  • Normally-closed contacts in series
  • Normally-open contacts in series
  • A single normally-closed contact
  • Normally-open contacts in parallel
  • Normally-closed contacts in parallel

Answer: Normally-open contacts in parallel

Question 48 What is the full form of NEMA ?

National Electronics Manufacturing Association
National Electrical Manufacturing Association 
National Electrotechnical Manufacturing Association 
National Electromechanical Manufacturing Association 

Answer: National Electrical Manufacturing Association 

Question 49 Which of the following is not element of SCADA:

  • SCADA Communication
  • Mono Terminal Units
  • PLCs
  • RTUs

Answer: Mono Terminal Units

Question 50 Identify the problem in this motor control PLC program:

  • Coil
  • Start contact
  • Seal-in contact
  • Stop contact
  • Power source

Answer: Seal-in contact


#4 PLC MCQ

Programmable Logic controller

Multiple choice questions

Question 1: The type of memory which is fast and temporarily stores the data which are immediately required for use is called as______.

a. HDD
b. ROM
c. RAM
d. SSD

Answer: RAM

Question 2: What is the largest integer number that a PLC counter function can reach if it uses a 16 bit register?

a. 32,768
b. 65,535
c. 65,536
d. 65,537
e. 32,767

Answer: 65,535

Question 3: How is the speed of operation of conventional relay system as compared to digital controllers?

a. Very slow
b. Very fast
c. Same
d. Almost similar

Answer: Very slow

Question 4: The PLC is used in _______.

a. Machine tools
b. Automated assembly equipment
c. Moulding and extrusion machines
d. All of the above

Answer: All of the above

Question 5: PLC can be ___________ in plant to change the sequence of operation.

a. only programmed
b. only reprogrammed
c. programmed and reprogrammed
d. able to give a set point

Answer: programmed and reprogrammed

Question 6: __________ of PLCs can be done in very little time.

a. Programming
b. Installation
c. Commissioning
d. All of the above

Answer: All of the above

Question 7: How is the noise immunity of PLCs to electrical noises as compared to that of conventional relay controllers?

a. poor
b. excellent
c. as good as noise immunity of conventional relay controllers
d. unpredictable

Answer: Poor

Question 8: The most popular language for PLCs is:

a. Ladder diagram
b. C++
c. OOP+
d. VHDL

Answer: Ladder diagram

Question 9: An AND function implemented in ladder logic uses:

a. Normally-closed contacts in series
b. Normally-open contacts in series
c. A single normally-closed contact
d. Normally-open contacts in parallel
e. Normally-closed contacts in parallel

Answer: Normally-open contact in series

Question 10: The PLC Can be categorized according to the

a. Power rating of the I/O module
b. Cost of the I/O module
c. Current rating of the I/O module
d. Number of I/O point

Answer: Number of I/O point

Top 10 PLC MCQ questions asked in previous year paper

Programmable Logic controller Multiple Choice Question

Top 10 PLC Programmable logic controller questions asked in various competitive exam. Please give this exam. This is free mock test and check your score.

First give this exam. If your answer is wrong then check below video for detail description of question

[ays_quiz id=”7″]

Series#1 ( Top 10 Questions )

Question 1 The acronym PLC stands for:

  1. Pressure Load Control
  2. Programmable Logic Controller
  3. Pneumatic Logic Capstan
  4. PID Loop Controller
  5. Pressure Loss Chamber

Answer: Programmable Logic Controller

Question 2 Ladder logic programming consists primarily of:

  1. Virtual relay contacts and coils
  2. Logic gate symbols with connecting lines
  3. Function blocks with connecting lines
  4. Text-based code
  5. Hieroglyphics

Answer: Virtual relay contacts and coils

Question 3 In a PLC, the scan time refers to the amount of time in which …..

  1. The technician enters the program
  2. Timers and counters are indexed by
  3. One “rung” of ladder logic takes to complete
  4. The entire program takes to execute
  5. Transmitted data communications must finish

Answer: The entire program takes to execute

Question 4 Identify the problem in this motor control PLC program:

  1. Coil
  2. Start contact
  3. Seal-in contact
  4. Stop contact
  5. Power source

Answer: Seal-in contact

Question 5 The Boolean representation of this PLC program is:

  1. ABC + D
  2. C + (A + B)D
  3. C + D(A + B)
  4. ABC + BD
  5. C(AB + D)

Answer: C(AB + D)

Question 6 The difference between online and offline PLC programming is . . .

  1. Whether the PLC is running or stopped
  2. Whether the programming PC has internet connectivity
  3. The type of programming cable used
  4. Where the edited program resides
  5. The type of programmer used

Answer: Where the edited program resides

Question 7 In PLC programming, a retentive function is one that:

  1. Defaults to the “on” state
  2. Comes last in the program
  3. Defaults to the “off” state
  4. Cannot be edited or deleted
  5. Is not reset after a power cycle

Answer: Is not reset after a power cycle

Question 8 Normally open contacts are open when:

  1. When Input is not energized
  2. When the input is energized
  3. When input is higher than 20 volts
  4. None of these

Answer: When Input is not energized

Question 9 An OR function implemented in ladder logic uses:

  1. Normally-closed contacts in series
  2. Normally-open contacts in series
  3. A single normally-closed contact
  4. Normally-open contacts in parallel
  5. Normally-closed contacts in parallel

Answer: Normally-open contacts in parallel

Question 10 A good application for a timed interrupt in a PLC program would be:

  1. A communications function block
  2. A PID function block
  3. A math function block
  4. A motor start/stop rung
  5. A “watchdog” timer

Answer: A PID function block

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FAQ’s

1. What is PLC ?

PLC stand for “Programmable Logic Controller”. It is a general purpose computer modified specifically to perform control task . It is a hardware device having microprocessor based control system. It is used in industrial automation.

2. What do you mean by PLC scan time?

PLC Scan Time is the time taken by the PLC to read the inputs, solve the Logic, and update the output is called a PLC Scan Time. This time is measured in millisecond .

3. Which is the most popular language in plc programming ?

The most popular language in plc programming is Ladder Logic Diagram.

4. What are the applications of PLC ?

PLC is used in industrial automation. These controllers can automate a specific process, machine function, or even an entire production line.

5. What are components of PLC system ?

There are major 6 components of PLC:
•Processor (CPU)
•Rack/Mounting
•Input Module
•Output Module
•Power Supply
•Programming Device/Unit

6. What is ladder diagram ?

Ladder diagram is the most popular programming language used in Plc programming. Ladder diagrams expresses a program as a series of “coils” and “contacts”, simulating the operation of electromechanical relays.
The advantage of ladder diagram is the familiarity many electricians have with the simple operation of relays.


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