Querying historical data in SCADA systems - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Output of a historical data query command

What is the output of this SCADA system command querying temperature data for the last hour?

SCADA systems

query historical_data --tag temperature --last 1h

A []

B Error: Invalid tag name

C [{"timestamp": "2024-04-27T13:00:00Z", "value": 22.5}, {"timestamp": "2024-04-27T13:30:00Z", "value": 23.0}]

D SyntaxError: Unexpected token '--'

💡 Hint

Check the tag name and time range format.

The command correctly queries the temperature tag for the last hour and returns two data points with timestamps and values.

❓ Configuration

intermediate

Configuring data retention for historical queries

Which configuration snippet correctly sets the data retention period to 30 days for historical data in the SCADA system?

A data_retention_period: 30d

B retention_period = "30 days"

C dataRetention: '30days'

D history_retention: 30

💡 Hint

Look for the exact key name and value format.

The correct configuration uses 'data_retention_period' with a value of '30d' to specify 30 days retention.

❓ Troubleshoot

advanced

Troubleshooting missing historical data

A user runs a query for historical pressure data but gets an empty result. What is the most likely cause?

SCADA systems

query historical_data --tag pressure --last 24h

A The SCADA system does not support querying pressure data.

B The query syntax is incorrect and causes no data to return.

C The data retention period is set to 7 days, so 24h data is missing.

D The pressure sensor was offline during the last 24 hours.

💡 Hint

Consider sensor availability and data collection.

If the sensor was offline, no data would be collected, resulting in an empty query result.

🔀 Workflow

advanced

Steps to export historical data for analysis

What is the correct order of steps to export historical SCADA data for external analysis?

A 1,2,4,3

B 2,1,4,3

C 1,4,2,3

D 1,3,2,4

💡 Hint

Think about querying, saving, verifying, then opening.

First query data, then save it, verify the saved file, and finally open it in the tool.

✅ Best Practice

expert

Best practice for optimizing historical data queries

Which practice best improves performance when querying large historical datasets in SCADA systems?

A Query all tags for the maximum available time range to avoid missing data.

B Query only the necessary tags and limit the time range.

C Run multiple queries in parallel without limiting data size.

D Export raw data daily and query only the exported files.

💡 Hint

Think about reducing data volume for faster queries.

Limiting tags and time range reduces data size and speeds up queries.