Lesson 05 – System control and sensors

Question 1

What are the two major tasks of a control?

Answer 1

• Evaluating input signal, e.g. from user-interaction, light barriers, switches, other sensors, etc.
• Providing output signals, e.g. to signal lights, motors, pneumatic actuators

Question 2

How are control systems in industrial environments usually realized?

Answer 2

-Realized by using programmable logic control (PLC)

Question 3

List five possible input and output signals to control

Answer 3

Input:
-User interface, door switch, temperature sensor, timer, water sensor

Output:
-Door lock, water valve, water pump, heating, motor

Question 4

List 3 special properties of a programmable logic control (PLC)

Answer 4

• Designed to be integrated in control cabinet.
• Programming interface for loading and manipulation of executed program using special programming software
• Interfaces to field busses and IO Components

Question 5

5. Difference between absolute rotary encoder and incremental rotary encoder?

Answer 5

• Absolute: mounted on shaft provides absolute position of shaft, keep information even when powered off -> never need calibration
• Incremental: mounted on shafts detects and measures movement and direction of rotation, but loses info at power-off -> needs to ‘’go-back’’ to home position for re-calibration

Question 6

What is the purpose of the field bus technology ?

Answer 6

• All I/ Os must be connected to the PLC.

- Instead installing cables from every sensor/ actuator to the PLC better use a field bus.

Question 7

What are the requirements on field busses?

Answer 7

• Allowing Real-Time communication

- Robustness against mechanical and electromagnetical disturbances in industrial environments

Question 8

Actuators

Answer 8

It is a type of motor that is responsible for moving or controlling a mechanism or system.
It is operated by a source of energy annd converts that energy into motion.

Question 9

Input/ Output signals

Answer 9

Input signals:

• digital-> For evaluation of light barriers, switches, etc
• counters: counting impulses.

Outputs signals:

• digital: driving signal lights, actuators,…
• CNC control: for the exact positioning of drives.
  (eg. in robot)