truST: IEC 61131-3 Structured Text for VS Code

Write, run and debug IEC 61131-3 Structured Text in VS Code, watch and force its I/O while it runs, design operator screens, and commission control loops, all in one extension. Programs compile to native code, and the complete compiler toolchain is part of the extension, so there is nothing else to install.

Structured Text in VS Code: a hover and completion, Start runs the program on the simulator, Live Values forces a level, and the debugger stops at a breakpoint and steps

Highlights

Language server. Diagnostics as you type that name the IEC 61131-3 rule, completion, hover, go to definition, find references, rename across files, formatting and refactorings, for Structured Text with classes, interfaces, methods and namespaces.
Native execution. Structured Text compiles through Rust into native code. The extension carries the compiler toolchain of its platform (rustc, rust-lld, the target libraries and the PLC program library), and the first build installs it: no download and no Rust installation of your own, offline too.
Run and debug. Run on the built-in simulator or on a runtime, with breakpoints, stepping, call stack and variables on the compiled program. Live Values reads, writes and forces inputs, outputs and memory while the program runs.
HMI Builder. Design operator screens with drag and drop, stored as TOML pages that diff and review like code. The runtime serves them at /hmi, with trends and alarms.
Devices & Connections. Find and configure Modbus TCP, MQTT with Sparkplug B, OPC UA, Beckhoff ADS, EtherCAT and GPIO devices, and the runtimes of a project.
Tests and interchange. Structured Text tests in the Testing view and through CodeLens, PLCopen XML import and export, and visual editors for ladder, SFC, Blockly and statecharts that keep a Structured Text companion.
Libraries and existing code. OSCAT, PLCopen Motion and truST's control, plant, alarm, HMI and communication libraries from truST: Open Libraries, and vendor profiles that read the Structured Text of CODESYS and TwinCAT, Siemens SCL and Mitsubishi GX Works3.
Control Studio. Identify a plant from experiments, tune and validate a controller against the model, apply it to a running loop with a bumpless transfer, and restore the previous settings when needed.

Quick start

Run truST: Create Project from the Command Palette (Ctrl+Shift+P), or press Start from example in the truST side panel.
Press Start on the Run card. The first build installs the compiler toolchain, then the program runs on the simulator.
Open Live Values to watch and force the I/O, set a breakpoint, and step through the scan.
Open Control Studio to tune a loop, or run truST: New HMI Screen to design an operator screen.

The debugger stepping through a compiled program, with its locals and call stack

An operator opens the LIC-101 faceplate of the hmi_equipment example at /hmi and raises its setpoint; the level follows

Commands you will use most

Command	What it does
truST: Create Project	Creates a project folder from a starter or an example.
truST: Compile	Checks the project's sources and shows the problems.
truST: Start Debugging / truST: Attach Debugger	Runs the program under the debugger, or attaches to a running runtime.
truST: Open Live Values	Shows and forces the program's I/O and memory.
truST: Open Control Studio	Identifies, tunes, validates and applies controllers.
truST: Open Devices & Connections	Finds and configures devices, runtimes and connections.
truST: New HMI Screen	Adds an operator screen to the project.
truST: Import PLCopen XML / truST: Export PLCopen XML	Exchanges projects with other PLC tools.
truST: Run All Tests	Runs the project's Structured Text tests.
truST: Install Toolchain from File	Installs a toolchain bundle file, for example another release's.

Build an HMI with your agent

The agent you already use in VS Code can author HMI pages with truST's nine hmi_* tools: they read the project's HMI and Structured Text documents, browse the component library, compose or refine a draft, and return rendered previews for the agent to inspect. A review opens in the HMI Builder with before and after images, where you apply or discard it; applying uses VS Code's Undo. The tools do not deploy the HMI or operate the controller. For an MCP client, run truST: HMI: Connect Agent Tools in the workspace and use the configuration it shows.

Requirements

VS Code 1.109 or later on Windows x64, macOS (Intel or Apple silicon) or Linux (x64 or arm64).
About 650 MB of disk space for the installed compiler toolchain.

Settings

The extension needs no settings to start. The truST section of the Settings editor holds the options, for example trust.diagnostics.showIecReferences, and the executable paths (trust.languageServer.executablePath, trust.runtime.executablePath, trust.debugAdapter.executablePath) for using your own builds.

Links

Licensed under MIT OR Apache-2.0.

truST

trust-platform