PLC

Question 1

What are programmable logic controllers (PLCs)?

Answer 1

Programmable devices used in control systems that respond to inputs and control different output devices.

Question 2

List the characteristics that make PLCs suitable for engineering and manufacturing environments.

Answer 2

• Reliable
• Rugged
• Easy to program
• Capable of working with a large number of input and output devices.

Question 3

What is a unitary PLC?

Answer 3

A PLC that has all components contained within a single housing.

Question 4

Describe modular PLCs.

Answer 4

PLCs made up of different modules that are connected together to form a customised device.

Question 5

What are rack mounted PLCs?

Answer 5

PLCs that have characteristics of both unitary and modular PLCs.

Question 6

What are the main components of a PLC?

Answer 6

• Power supply
• Central processing unit (CPU)
• Programming device
• Input and output (I/O) modules/devices

Question 7

True or False: PLCs can only control a limited number of input and output devices.

Answer 7

False

Question 8

Fill in the blank: A _______ PLC has all components contained within a single housing.

Answer 8

[unitary]

Question 9

What is the function of the central processing unit (CPU) in a PLC?

Answer 9

It processes the inputs and executes the control logic.

Question 10

What is the role of a programming device in a PLC?

Answer 10

To program the PLC for specific control tasks.