OpenPLC v3 + Modbus TCP: Open-Source PLC Architecture
OpenPLC v3 reference architecture with Modbus TCP — runtime internals, IEC 61131-3 languages, hardware targets, and a production deployment pattern for open-source PLCs in 2026.
Modbus Protocol: The Complete Technical Guide
Complete Modbus deep dive — RTU vs TCP vs ASCII, frame structure, function codes, register maps, error handling, and modern Modbus-to-MQTT bridging patterns.