PLCs

Question 1

What is a PLC?

Answer 1

A PLC (Programmable Logic Controller) is a programmable device used to respond to inputs and control different output devices

Question 2

What are some different type of PLC?

Answer 2

Unitary PLC (all components in single housing)
Modular PLC (made up of different modules connected together)
Rack mounted PLC (combination of unitary and modular PLCs)

Question 3

What are the main components of a PLC?

Answer 3

Power supply
CPU
Programming device
I/O devices

Question 4

What is ladder logic?

Answer 4

A programming language that uses graphical diagram to represent a program based on circuit diagrams of relay logic hardware

Question 5

What are advantages and limitations to ladder logic?

Answer 5

Advantages: Simple to use, easy to understand/find errors
Limitations: Lacks flexibility when complex programs required

Question 6

What does a motor driver IC (Integrated Circuit) do? What are 2 examples of motor driver ICs?

Answer 6

Provides more current as programmable devices don’t provide enough current to drive motor outputs alone
Darlington driver IC (when simple functionality needed) and L293D (when complex functions needed)

Question 7

What do interface devices do?

Answer 7

Allow communication between the PLC and the input/output devices

Question 8

What are some examples of applications of PLCs in engineering?

Answer 8

Controlling movement of robotic arms
Sensing, measurement and sorting on conveyor belts
SCADA (Supervisory Control And Data Acquisition)

Question 9

What is SCADA?

Answer 9

SCADA (Supervisory Control And Data Acquisition) is software used to supervise, monitor and control industrial processes

Question 10

What does a SCADA system usually consist of?

Answer 10

Supervisory computers
Remote terminal units
PLCs
Communications devices
HMI (Human-Machine Interface)