notes from the
bench.
Write-ups from an automation workbench: redundant PLCs, industrial networks, HMIs, and the edge PCs that tie them together. What was built, how, and what broke along the way.
Notes
A redundant CODESYS PLC pair behind one floating IP
Two controllers, one address: CODESYS redundancy on WAGO PFC300s, a virtual IP that follows the active PLC, and an OPC UA struct that every HMI reads, so failover never shows up downstream.
Remote access to a PLC network without opening a port
One outbound Cloudflare Tunnel from an edge PC does two jobs: login-gated HMIs any browser can open, and private engineering access to the PLC subnet that only enrolled laptops can reach.
Cheatsheets for the everyday stack
A set of plain-HTML reference pages for the tools an automation engineer touches every day, from Structured Text and Modbus registers to systemd and regex.