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Logging Mitsubishi PLC Data in Real Time on a Raspberry Pi
How I bridge a Mitsubishi PLC to a Raspberry Pi for continuous, reconnect-safe register polling — and why the edge is the right place to do it.
Factory PLCs are great at control but terrible at memory. They run the line beautifully and then forget everything the moment a batch ends. If you want history, dashboards, or reports, you need something sitting next to the PLC that listens and remembers.
On the check-weigher line I put a Raspberry Pi in exactly that seat. It polls the PLC's weight and status registers on a tight loop, buffers readings locally, and survives the inevitable network blips that come with factory-floor networking.
The key lesson: treat the connection as unreliable by default. Wrap every read in reconnect logic, keep a local buffer, and never assume the last poll succeeded. Once the data is reliably captured at the edge, everything downstream — reports, dashboards, alerts — becomes easy.