Historian architecture overview in SCADA systems - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Key components of a Historian architecture

Which of the following is NOT typically a core component of a Historian architecture in SCADA systems?

A Compiler for converting source code into machine code

B Data acquisition module that collects real-time data from sensors

C Data storage optimized for time-series data

D User interface for data visualization and reporting

💡 Hint

Think about what a Historian system does with data rather than software development tools.

A Historian architecture includes data acquisition, storage, and visualization components. A compiler is unrelated to Historian functions.

💻 Command Output

intermediate

Output of a data query in Historian

Given a query to retrieve temperature data points from a Historian database for the last hour, what is the expected output format?

SCADA systems

SELECT timestamp, temperature FROM historian_data WHERE timestamp >= NOW() - INTERVAL '1 hour';

A {"temperature": 22.5, "timestamp": "2024-06-01T10:00:00Z"}

B [{"timestamp": "2024-06-01T10:00:00Z", "temperature": 22.5}, {"timestamp": "2024-06-01T10:05:00Z", "temperature": 22.7}]

C [22.5, 22.7, 23.0]

D Error: Invalid query syntax

💡 Hint

Think about how time-series data is usually returned with timestamps and values.

The query returns a list of records with timestamp and temperature fields in JSON format.

🔀 Workflow

advanced

Data flow in Historian architecture

Arrange the following steps in the correct order for data flow in a Historian architecture.

A 1,2,3,4

B 2,1,3,4

C 1,3,2,4

D 3,1,2,4

💡 Hint

Data must be collected before preprocessing and storage.

The correct flow is to first acquire data, then preprocess, store, and finally visualize it.

❓ Troubleshoot

advanced

Troubleshooting missing data in Historian

If a Historian system shows gaps in recorded data for certain time intervals, what is the most likely cause?

A The Historian database automatically deletes old data

B Data visualization tool is incompatible with the Historian

C Sensor failure or communication loss during those intervals

D User interface is not refreshing properly

💡 Hint

Consider what affects data collection at the source.

Gaps usually happen because sensors or communication channels fail to send data.

✅ Best Practice

expert

Best practice for Historian data retention

What is the best practice for managing data retention in a Historian system to balance storage and analysis needs?

A Store only data from critical sensors and ignore others

B Keep all raw data indefinitely without any aggregation or deletion

C Delete all data older than one day to save storage space

D Aggregate older data into summaries and delete raw data after a retention period

💡 Hint

Think about how to keep useful data while saving space.

Aggregating older data and deleting raw data after a period balances storage and analysis needs.