// the find
rwbl/rOpen62541
rOpen62541 is an open-source library wrapper for the industrial open62541 OPC UA protocol stack, specifically optimized for the ESP32-S3 Dual-Core architecture.
A B4R (Basic4Android's microcontroller dialect) wrapper around the open62541 OPC UA stack, targeting ESP32-S3 dual-core boards as a server-only device. It's for hobbyists already in the B4X ecosystem who want to expose sensor/actuator data to industrial OPC UA clients like Node-RED or SCADA tools, not for anyone building a production gateway.
Decent breadth of runnable examples (env simulation, method callbacks, I/O mapping, node ID lookups, servo control) each paired with a matching client in B4J, Node-RED, or Python, so you can actually see the wire protocol working end to end. It builds on open62541 rather than reimplementing OPC UA, and the docs folder (dev notes, function reference, troubleshooting, tutorials) is more organized than most single-author embedded projects bother with. Cross-core FreeRTOS handling for the ESP32-S3's two cores is called out explicitly, which is the part people usually get wrong first.
Server-only — there's no client support, so it can't talk to other OPC UA servers, only be talked to. It's hard-locked to B4R, a proprietary niche language; nothing here is reusable if you're writing in plain C/C++ or Arduino without buying into the B4X toolchain. The README itself flags pre-v1.0 status with API changes still possible and testing/documentation incomplete, and with 1 star, 0 forks, and a single contributor there's no external validation that the OPC UA implementation is spec-correct beyond the author's own client testing. The repo also leans heavily on AI-assisted development per the credits/disclaimer, with no indication of independent code review of the generated mutex/type-interceptor logic that handles cross-core safety — exactly the kind of code where subtle bugs are expensive.