Programmable Logic Controller (PLC) MCQ Questions and Answers for Practice

1. PLC is an acronym of _______________ Logic Controller

1. Programmable
2. Peripheral
3. Periodic
4. Pneumatic

2. Unitary PLC has 20 inputs and __________ outputs

1. 20
2. 18
3. 12
4. 10

3. Ladder Logic Programming consists primarily of

1. logic gate symbol and connecting lines
2. virtual relay contacts and coils
3. function blocks and connecting lines
4. text-based codes

4. PLCs having less than __________ inputs and outputs are called as Small PLC

1. 50
2. 100
3. 150
4. 200

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

1. timer and counters are indexed by
2. one rung of ladder logic takes to get complete
3. the entire program takes to excecute
4. the technician enters the program

6. HMI means __________ Machine Interface

1. Human
2. Hard
3. Heart
4. High

7. Medium PLC has _____________ inputs and outputs

1. 100 - 200
2. 1000 - 4000
3. 2000 - 4000
4. 4000 - 8000

8. Main difference between online and offline PLC programming is

1. where the edited program resides
2. whether the programming PC has internet connectivity
3. whether the PLC is running or stopped
4. the type of program used

9. ______________ language can be programmed interactively with the PLC

1. Online
2. Offline
3. Basic
4. C

10. For a 16-bit register, which is the largest integer number a PLC counter function can reach

1. 32,768
2. 65,535
3. 65,536
4. 32,767

11. To protect a PLC from any incoming surges from the field, an isolated device such as ____________ is used.

1. Transformer
2. Transducer
3. ADC
4. DAC

12. In PLC programming, a retentive function is one that

1. Default points to the On State
2. Default points to the Off State
3. is not reset after a power cycle
4. cannot be edited or deleted

13. An OR function implemented in Ladder logic uses

1. normally closed contacts in series
2. normally open contacts in series
3. normally closed contacts in parallel
4. normally open contacts in parallel

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

1. A math function block
2. A PID function block
3. A communication function block
4. A motor start/stop rung

15. The __________________ instruction is used to turn an output ON or OFF after its time has been on for a preset time interval

1. retentive time
2. timer and delay
3. timer off delay
4. none of these