Design an industrial sensor monitoring system
PremiumIoT systemMedium
- Edge gateway
- OPC UA
- Modbus
Quick answer
This ioT system interview question asks you to design an industrial sensor monitoring system. Aim for a design that collects data from many devices and acts on it reliably, then explain device connections, ingestion, storage and trade-offs. Interviewers want to see how you handle unreliable networks, device scale and data volume.
The problem
Design an industrial sensor monitoring system: edge gateways in each factory read temperature, pressure and vibration sensors from machines and send them to a cloud platform for dashboards and maintenance alerts. The hard parts are slow factory uplinks, WAN outages and keeping the plant network safe.
A manufacturer runs 40 plants. Scalar sensors are wired to PLCs, which the gateway reads over OPC UA or Modbus TCP. Vibration sensors are wired to data-acquisition cards in the gateway, because PLC polling cannot carry a 10 kHz signal. Engineers want live dashboards, alarms when a machine runs hot, and early warning that a bearing is wearing out.
What must an industrial sensor monitoring system do?
- Live data: Every scalar sensor (temperature, pressure, current) is visible in the cloud within 5 seconds of being read.
- Local alarms: Threshold alarms fire at the plant within 10 seconds, even when the WAN link is down.
How well must it do it?
- Plant safety: No connection from the internet into the plant network; gateways only make outbound connections.
- Uplink budget: Monitoring traffic uses at most half of each plant's 20 Mbit/s uplink.
What scale should you design for?
Use these numbers in your estimates.
The scale numbers unlock with this questionUnlock
Key concepts
- Edge gateway
- OPC UA
- Modbus
- Store and forward
- Sparkplug b
- Vibration analysis
How you’ll practise
- Requirements
- Estimate
- Device and connectivity
- Ingestion and processing
- Device management and updates
- Wrap-up
Lala, personalized to you, gives a hint when you ask and reviews your design when you are ready.
What do interviewers look for?
In any IoT system design round.
- Clarifies device count, message rate and payload size
- Handles devices that go offline and reconnect
- Plans ingestion that absorbs bursts
- Separates hot real-time data from long-term storage
- Covers device identity, updates and security
- Explains what runs on the device and what runs in the cloud
Questions people ask about this interview question
- Which design type is this question?
- It is an ioT system question. You design an industrial sensor monitoring system and explain your choices the way you would in an interview.
- Is this question asked at entry level?
- It is marked Medium. Entry-level engineers can practise it, but it expects you to reason about requirements and trade-offs, not only list components.
- What should I cover first?
- Start with the devices, what they send, how often and what must happen with it. Agree on scope with the interviewer before you design anything.
- Can I practise it for free?
- It is a premium question. Sign up and unlock it once for 10 credits; it then stays unlocked. When you finish, Lala, your personalized AI mentor, can review your design for 30 credits.
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Updated · Written by the SevyDevy team