Programmable Logic Controllers Multiple Choice Questions

Programmable Logic Controllers Multiple Choice Questions

Question 1

The acronym PLC stands for:

(A) Pressure Load Control
(B) Programmable Logic Controller
(C) Pneumatic Logic Capstan
(D) PID Loop Controller
(E) Pressure Loss Chamber

Answer : B

Question 2

Ladder logic programming consists primarily of:

(A) Virtual relay contacts and coils
(B) Logic gate symbols with connecting lines
(C) Function blocks with connecting lines
(D) Text-based code
(E) Hieroglyphics

Answer : A

Question 3

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

(A) the technician enters the program
(B) timers and counters are indexed by
(C) one “rung” of ladder logic takes to complete
(D) the entire program takes to execute
(E) transmitted data communications must finish

Answer : D

Question 4

Identify the problem in this motor control PLC program:

Motor PLC Program

(A) Coil
(B) Start contact
(C) Seal-in contact
(D) Stop contact
(E) Power source

Answer : C

Question 5

The Boolean representation of this PLC program is:

PLC Boolean Logic

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

Answer : E

Question 6

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

(A) whether the PLC is running or stopped
(B) whether the programming PC has internet connectivity
(C) the type of programming cable used
(D) where the edited program resides
(E) the type of programmer used

Answer : D

Question 7

In PLC programming, a retentive function is one that:

(A) Defaults to the “on” state
(B) Comes last in the program
(C) Defaults to the “off” state
(D) Cannot be edited or deleted
(E) Is not reset after a power cycle

Answer : E

Question 8

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 : B

Question 9

An OR 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 : D

Question 10

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

(A) A communications function block
(B) A PID function block
(C) A math function block
(D) A motor start/stop rung
(E) A “watchdog” timer

Answer : B

Credits : by Tony R. Kuphaldt

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6 thoughts on “Programmable Logic Controllers Multiple Choice Questions”

  1. Question 5 is erroneous,because input B and D should be negated, and thus that correct answer must have B and D with a bar on top,not so?


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