Open Industry Project - GDextension Component

This component is for the Open Industry Project (OIP). It exposes a single OIPComms singleton that drives multiple industrial-comms protocols through one unified read/write/poll API. Each tag group is registered with a protocol string that selects the backend.

protocol	Backend	Source
ab_eip, modbus_tcp	libplctag	prebuilt in lib/
opc_ua	open62541	prebuilt in lib/
s7	Siemens S7 PUT/GET	vendored in src/S7Com.cpp
ads	Beckhoff/ADS	git submodule under ads/
rtde	Universal Robots Real-Time Data Exchange (v2)	hand-rolled in src/rtde_client.cpp, no external dep

Prebuilt-library commits (built from source, dropped into lib/):

• https://github.com/libplctag/libplctag/commit/c55bc5876d938dda1c609750cde5ae4812d7b8a8
• https://github.com/open62541/open62541/commit/de932080cf1264748b5b757dd7e87e422c4df0aa

The Beckhoff ADS library has two variants and the build picks one per platform:

• Windows: links against the locally-installed TcAdsDll.dll (Beckhoff's official client) via the USE_TWINCAT_ROUTER define. Required because TwinCAT 3 build 4026 enforces Secure ADS, and the standalone library only speaks plain TCP — its requests are silently dropped by 4026's runtime. Requires TwinCAT to be installed locally; the GDExtension delay-loads TcAdsDll.dll at runtime, resolving the install path from the Windows registry (see src/tcads_loader.cpp). The DLL itself is not redistributed with this project.
• Linux / macOS: uses the standalone library (its own AmsRouter, plain TCP). This is the standalone lib's documented use case — connecting from a non-TwinCAT host to a remote TwinCAT system. A route entry must be configured on the remote TwinCAT for the local AmsNetId.

RTDE specifics

The RTDE backend talks to Universal Robots controllers (real hardware or URSim) on TCP port 30004 using protocol version 2. The full variable vocabulary is documented in the official UR RTDE guide. Tag-group fields:

• Gateway: robot IP address (e.g. 192.168.56.101).
• Path / CPU: unused.
• Polling rate (ms): mapped to the controller's stream frequency (Hz = 1000 / polling_ms), clamped to [1, 500] Hz.

Tag names follow UR's RTDE variable vocabulary. Vector fields are read element-by-element using name[index] syntax. A few examples:

• actual_q[0] … actual_q[5] — joint angles, one tag per joint (read with read_float64).
• actual_TCP_pose[0] … actual_TCP_pose[5] — TCP pose components.
• runtime_state — controller program state (read with read_uint32).
• input_int_register_0 — writable INT32 register (write with write_int32).
• input_double_register_0 — writable DOUBLE register (write with write_float64).

Tag names that begin with input_ are routed to the input recipe automatically and are writable from this side; everything else lives in the output recipe and is read-only.

See PR on Open Industry Project https://github.com/open62541/open62541

Building from Source

Please read Godot's documentation on building from source and GDextension:

• https://docs.godotengine.org/en/stable/contributing/development/compiling/index.html
• https://docs.godotengine.org/en/stable/tutorials/scripting/gdextension/gdextension_cpp_example.html

After cloning, fetch the submodules (godot-cpp and ads):

git submodule update --init --recursive

Build command: scons platform=windows debug_symbols=yes

The output of building will be the DLLs located in: https://github.com/bikemurt/OIP_gdext/tree/main/demo/bin/windows

The DLLs, and oip_comms.gdextension file must be copied to the oip_comms dock plugin for the main Open Industry Project repo: Open-Industry-Project/addons/oip_comms/bin/. Right now just building for Windows, but should be extendable to other platforms.

This GDextension as well as the libs (libplctag, open62541) are built with the /MT flag. According to dumpbin this removes any external deps on MSVC runtime and should improve portability.

https://stackoverflow.com/a/56061183/7132687

This project uses the standard library.

Documentation

Update https://github.com/bikemurt/OIP_gdext/blob/main/doc_classes/OIPComms.xml as required and rebuild.

Debugging

As long as you build with debug_symbols=yes, the 4.5 branch of OIP will be able to debug this GDextension application.

Inside the .vs/ folder you can create launch.vs.json:

{
	"version": "0.2.1",
	"defaults": {},
	"configurations": [
		{
			"type": "default",
			"project": "location_of_oip_4.5_build\\godot.windows.editor.x86_64.exe",
			"name": "Godot Editor",
			"args": [ "location_of_project\\Open-Industry-Project\\project.godot" ]
		}
	]
}

Then you can launch the OIP editor from Visual Studio and drop in breakpoints to test.

License

This project is licensed under the MIT License.

For the licenses of bundled and linked third-party libraries (godot-cpp, Beckhoff ADS, libplctag, open62541, TcAdsDll), see THIRD_PARTY_LICENSES.md.