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:
(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:
(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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