Data quality flags in SCADA systems - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set the data quality flag to 'GOOD' when the sensor reading is valid.

SCADA systems

if sensor_reading_valid:
    data_quality_flag = '[1]'

Drag options to blanks, or click blank then click option'

AGOOD

BUNKNOWN

CERROR

DBAD

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'BAD' or 'ERROR' flags for valid data.

The flag 'GOOD' indicates the sensor reading is valid and reliable.

2fill in blank

medium

Complete the code to mark the data quality flag as 'BAD' if the sensor reading is out of range.

SCADA systems

if sensor_reading < min_value or sensor_reading > max_value:
    data_quality_flag = '[1]'

Drag options to blanks, or click blank then click option'

AGOOD

BVALID

CUNKNOWN

DBAD

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'GOOD' flag for out of range data.

The 'BAD' flag is used when data is outside expected limits, indicating poor quality.

3fill in blank

hard

Fix the error in the code to correctly assign the 'UNKNOWN' flag when sensor status is unclear.

SCADA systems

if sensor_status == 'uncertain':
    data_quality_flag = '[1]'

Drag options to blanks, or click blank then click option'

AUNKNOWN

BBAD

CGOOD

DERROR

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning 'GOOD' or 'BAD' flags when status is uncertain.

The 'UNKNOWN' flag is used when the sensor status cannot be determined clearly.

4fill in blank

hard

Fill both blanks to set the flag to 'ERROR' if sensor reading is None and log the issue.

SCADA systems

if sensor_reading is [1]:
    data_quality_flag = '[2]'
    log_issue('Sensor reading missing')

Drag options to blanks, or click blank then click option'

ANone

BGOOD

CERROR

DBAD

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'BAD' or 'GOOD' flags for missing data.

When the reading is None, it means missing data, so the flag should be 'ERROR'.

5fill in blank

hard

Fill all three blanks to create a dictionary mapping sensor IDs to their data quality flags, including only sensors with 'GOOD' or 'UNKNOWN' flags.

SCADA systems

quality_map = {sensor_id: data_quality_flags[sensor_id] for sensor_id in sensor_ids if data_quality_flags[sensor_id] [1] ['GOOD', 'UNKNOWN'] and sensor_id [2] None and data_quality_flags[sensor_id] [3] 'BAD'}

Drag options to blanks, or click blank then click option'

Ain

Bis not

C!=

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using '==' instead of 'in' for list membership.

Using '==' instead of '!=' to exclude flags.

The 'in' operator checks if the flag is in the list. 'is not' checks sensor_id is not None. '!=' excludes 'BAD' flags.

Practice

1. What does a GOOD data quality flag indicate in a SCADA system?

easy

A. The sensor is offline and not sending data.

B. The sensor data is missing or unavailable.

C. The sensor data is suspected to be incorrect.

D. The sensor data is reliable and accurate.

Solution

1. Step 1: Understand the meaning of data quality flags

   Data quality flags classify sensor data status to help users trust or ignore readings.

2. Step 2: Identify the meaning of the GOOD flag

   The GOOD flag means the data is reliable and accurate, suitable for use in decisions.

3. Final Answer:

   The sensor data is reliable and accurate. -> Option D

4. Quick Check:

   GOOD flag = reliable data [OK]

Hint: GOOD means data is trustworthy and accurate [OK]

Common Mistakes:

• Confusing GOOD with MISSING or BAD flags
• Assuming GOOD means sensor is offline
• Mixing SUSPECT with GOOD data

2. Which of the following is the correct way to represent a BAD data quality flag in a SCADA system configuration file?

easy

A. flag = "BAD"

B. flag = BAD

C. flag = 'bad'

D. flag = bad

Solution

1. Step 1: Review syntax for string assignment in configuration

   Flags are usually strings and must be enclosed in quotes to be valid.

2. Step 2: Identify correct string syntax for BAD flag

   Using double quotes around "BAD" is correct; unquoted or lowercase without quotes is invalid.

3. Final Answer:

   flag = "BAD" -> Option A

4. Quick Check:

   String flags need quotes [OK]

Hint: Use quotes around string flags in configs [OK]

Common Mistakes:

• Omitting quotes around string values
• Using lowercase without quotes
• Confusing variable names with string literals

3. Given the following SCADA data quality flag array: flags = ["GOOD", "SUSPECT", "BAD", "GOOD", "MISSING"], which flags indicate data that should be excluded from analysis?

medium

A. ["BAD", "MISSING"]

B. ["SUSPECT", "GOOD"]

C. ["GOOD", "SUSPECT"]

D. ["GOOD", "MISSING"]

Solution

1. Step 1: Identify flags that mark unreliable data

   BAD and MISSING flags indicate data that is incorrect or unavailable and should be excluded.

2. Step 2: Match these flags to the options

   ["BAD", "MISSING"] correctly lists BAD and MISSING as flags to exclude from analysis.

3. Final Answer:

   ["BAD", "MISSING"] -> Option A

4. Quick Check:

   Exclude BAD and MISSING data [OK]

Hint: Exclude BAD and MISSING flags from analysis [OK]

Common Mistakes:

• Including GOOD or SUSPECT data for exclusion
• Confusing SUSPECT as always bad
• Ignoring MISSING data in filtering

4. You have a SCADA script that filters out BAD data using:

filtered = [d for d in data if d.flag != "BAD"]

but it still includes some BAD data. What is the likely cause?

medium

A. The data list is empty, so filtering does nothing.

B. The list comprehension syntax is incorrect and causes errors.

C. The flag comparison is case-sensitive and some flags are lowercase "bad".

D. The filter should use == instead of != to exclude BAD data.

Solution

1. Step 1: Analyze the filtering condition

   The condition excludes items where flag equals "BAD" exactly, case-sensitive.

2. Step 2: Identify case sensitivity issue

   If some flags are lowercase "bad", they won't match "BAD" and won't be excluded.

3. Final Answer:

   The flag comparison is case-sensitive and some flags are lowercase "bad". -> Option C

4. Quick Check:

   Case sensitivity causes filtering errors [OK]

Hint: Check case sensitivity in string comparisons [OK]

Common Mistakes:

• Assuming != excludes all BAD flags regardless of case
• Thinking list comprehension syntax is wrong
• Using wrong comparison operator

5. You want to create a SCADA alert that triggers only when sensor data is either BAD or MISSING. Which logical condition correctly implements this?

hard

A. if flag == "BAD" and flag == "MISSING":

B. if flag == "BAD" or flag == "MISSING":

C. if flag != "BAD" or flag != "MISSING":

D. if flag == "GOOD" or flag == "SUSPECT":

Solution

1. Step 1: Understand alert condition requirements

   The alert should trigger if the flag is BAD or MISSING, meaning either condition is true.

2. Step 2: Choose correct logical operator

   Using 'or' checks if flag equals BAD or equals MISSING, which matches the requirement.

3. Final Answer:

   if flag == "BAD" or flag == "MISSING": -> Option B

4. Quick Check:

   Use 'or' to combine conditions for alert [OK]

Hint: Use 'or' to check multiple flag conditions [OK]

Common Mistakes:

• Using 'and' which requires both flags simultaneously
• Using negation incorrectly
• Checking for GOOD or SUSPECT instead