nrc story 2 Flashcards
(3 cards)
Describe your work with developing a thermal test bench
At the NRC, I also worked on a project involving our thermal test bench, which was used to evaluate the thermal durability of 3D-printed metal materials by subjecting them to cycles of high heat and extreme cold.
My responsibility was to design and implement a system for cycle timing, anomaly detection, and alerting.
Our team installed a PLC to monitor and log the timing and completion of each thermal cycle.
I used Modbus TCP to poll the PLC at intervals from an edge node.
If the system detected a deviation beyond a defined threshold—such as a heater failing to reach temperature within a safe time window— an alert was pushed to our Microsoft Teams channel using a webhook, ensuring the research team could respond quickly.
This system ensured quick detection of equipment failure, and prevented data contamination from invalid test runs.
Why did you choose Modbus TCP instead of serial-based Modbus RTU or another protocol like OPC-UA?
We chose Modbus TCP because the PLC and edge node were both on the same internal Ethernet subnet. Modbus TCP provided simple, stateless polling and was **easy to implement **using open-source Python libraries like pymodbus.
How did you handle Modbus register mapping and decoding?
The PLC exposed specific holding registers with well-defined offsets for state codes and timestamps.
I worked with the instrumentation lead to define a shared register map.
On the edge node, my Python script used pymodbus.client to poll those registers, decode 16-bit values into timestamps or state flags, and translate those into structured logs for our test cycles.
