The Challenge
To evaluate the elemental composition of metal powder during a print, we needed to integrate an optical spectrometer to capture plasma emissions excited by the printer's laser. However, the spectrometer must only collect data when the building platform and recoater blade are stationary. Because commercial 3D printers are closed systems, we had to reverse-engineer the machine's internal states to synchronize our external sensors.
Network Wiretapping & Data Capture
Working alongside senior engineers, we achieved this by hardware tapping the machine's Industrial PC (IPC) to eavesdrop on the internal Ethernet Powerlink (EPL) V2 network communications.
- Utilized Wireshark to capture and filter network traffic between the IPC and internal components (servomotors, stepper motors).
- Monitored a live titanium print job over 30.6 hours, capturing 337 files containing over 168 million individual network packets.
Python Data Pipeline & Optimization
With the raw network traffic captured, the next step was parsing the hex strings into usable integer formats and plotting them over time to find visual patterns corresponding to physical machine movements.
- Developed Python scripts utilizing Pandas and Matplotlib to generate 3x4 grid graphs of different packet nodes against print time.
- Optimized data processing loads by testing different sample sizes. I determined that down-sampling to alternate rows (8,279 rows) provided the perfect balance—saving significant processing power while maintaining the distinct saw-tooth fidelity of the graphs.
Reverse-Engineering Results
To verify what these mysterious packet graphs represented, I cross-referenced their visual peaks and troughs against our known InfluxDB telemetry data (which tracked actual recoater speed, dispenser position, and filter pressure).
Through this analysis, I successfully proved that "Node ID 2" perfectly correlated with the position and speed of the recoater blade. Deciphering these packets established the crucial baseline needed to automatically trigger the spectrometer and other quality-assurance sensors exactly when the machine was in the correct state.