Disadvantage: faults, power cuts and hacking

Name:

Date:

Class:

Quick Questions

Shade in the A or B circle for each question.

1. A temperature sensor in a greenhouse is faulty and always reads 10°C. What is the most likely result?

A The microprocessor repairs the sensor by itself

B The heater may stay on and overheat the plants

2. Which statement about power cuts and automated systems is correct?

A No power means the system cannot work

B Automated systems keep working without power

3. Which is a risk of connecting an automated system to a network such as the internet?

A Hackers could take control of it or stop it

B The sensors will always give wrong readings

4. Which is the best way to reduce harm when an automated system fails?

A Have a backup system or manual control

B Remove all human workers from the site

5. A power cut stops an automated factory line. Which type of problem is this?

A A hacking attack on the microprocessor

B A power failure that stops the whole process

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1IF sensor_reading = 999 THEN		AThe microprocessor only sees what the sensor sends. A faulty sensor gives wrong data, so wrong decisions are made.
2IF mains_power = OFF THEN		BConnected systems can be hacked. A cyber attack can change settings or stop the system, so security is needed.
3A backup power supply keeps the automated system working during a power cut		CIF system_fault = TRUE THEN SWITCH TO manual_control ENDIF
4Manual control lets a person take over when the automated system fails		DA faulty sensor is sending a wrong reading, so the system may react incorrectly
5A hacker cannot harm a system that is connected to a network		EIF mains_power = OFF THEN USE battery_backup ENDIF
6A faulty sensor is not a problem because the microprocessor always knows the right reading		FA power cut has happened, so the system may stop working unless there is a backup

Definitions

system failure

Fill in the Blanks

Complete each line of code by filling in the missing parts.

__ sensorValue < 0 THEN OUTPUT "Sensor fault" ENDIF

IF mainPower _ FALSE THEN backupOn ← TRUE ENDIF

IF attempts _ 3 THEN OUTPUT "Possible hacking" ENDIF

IF autoFailed = TRUE THEN mode ← "MANUAL" _____

IF temp < -50 __ temp > 150 THEN OUTPUT "Faulty sensor" ENDIF

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A temp ← READ_SENSOR()

B IF temp = -999 THEN

C fault ← FALSE

D ENDIF

Question 2

A IF mainPower = OFF THEN

B alarm ← TRUE

C SWITCH OFF backupBattery

D ENDIF

Question 3

A attempts ← 0

B WHILE attempts > 3

C INPUT password

D attempts ← attempts + 1

E ENDWHILE

Question 4

A IF autoFailed = TRUE THEN

B DISABLE autoControl

C ENABLE manualControl

D MUTE alarm

E ENDIF

Question 5

A IF sensorOK = TRUE THEN

B USE lastGoodValue

C LOG fault

D ENDIF

Answer Key

Disadvantage: faults, power cuts and hacking

Section A: Quick Questions

B — The heater may stay on and overheat the plants

A — No power means the system cannot work

A — Hackers could take control of it or stop it

A — Have a backup system or manual control

B — A power failure that stops the whole process

Section B: Match the Pairs

IF sensor_reading = 999 THEN → A faulty sensor is sending a wrong reading, so the system may react incorrectly

IF mains_power = OFF THEN → A power cut has happened, so the system may stop working unless there is a backup

A backup power supply keeps the automated system working during a power cut → IF mains_power = OFF THEN USE battery_backup ENDIF

Manual control lets a person take over when the automated system fails → IF system_fault = TRUE THEN SWITCH TO manual_control ENDIF

A hacker cannot harm a system that is connected to a network → Connected systems can be hacked. A cyber attack can change settings or stop the system, so security is needed.

A faulty sensor is not a problem because the microprocessor always knows the right reading → The microprocessor only sees what the sensor sends. A faulty sensor gives wrong data, so wrong decisions are made.

Section C: Definitions

system failure — When an automated system stops working or is harmed, for example by a faulty sensor, a power cut or hacking, so the whole process may fail. A backup or manual control helps.

Section D: Fill in the Blanks

IF sensorValue < 0 THEN
    OUTPUT "Sensor fault"
ENDIF

IF mainPower = FALSE THEN
    backupOn ← TRUE
ENDIF

IF attempts > 3 THEN
    OUTPUT "Possible hacking"
ENDIF

IF autoFailed = TRUE THEN
    mode ← "MANUAL"
ENDIF

IF temp < -50 OR temp > 150 THEN
    OUTPUT "Faulty sensor"
ENDIF

Section E: Spot the Error

C — A reading of -999 means the sensor is giving a wrong value. The fault flag must be set to TRUE so the system knows the sensor is faulty.

C — When the main power is cut, the system should switch to the backup battery. Switching the battery off means no power at all, so the system fails.

B — The loop should run while attempts is LESS than 3. With > 3 it never runs, so the password check that limits hacking attempts is skipped.

D — If the automatic system fails, staff must be warned. The alarm should be sounded, not muted, so people can use manual control.

A — The backup action is for a faulty sensor, so the test should be sensorOK = FALSE. With TRUE it would ignore the sensor even when it works.