Raspberry Pi - PLC Programming & Automation

Docker on a Plant-Floor Raspberry Pi: Restart Policy, Log Rotation and the Container That Filled the Card

by PLC

The card's layout: the containers JSON log with no cap, overlay2 growing with every pull, named volumes holding the data, the journal capped at 10 % of the filesystem, image metadata

Keeping a Docker Raspberry Pi logger alive in a panel: restart unless-stopped, json-file max-size, journald caps, and the log that filled the card.

Writing a Setpoint Back to the PLC from a Pi: The Handshake That Stops It Being a Safety Problem

by PLC

The write path from dashboard to Pi to CompactLogix, with the panel selector switch drawn as a hard-wired input beside the controller and no safety tag anywhere on the path

Writing a setpoint to the PLC from a Raspberry Pi without it becoming a safety problem: request tags, panel key, range check, stale heartbeat, ack.

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