LinuxCNC for VSCode

Language support for LinuxCNC configuration files: .hal (HAL), .ini (machine config), and .ngc (G-code).

Features

• Syntax highlighting + semantic highlighting for HAL / INI / G-code
• Validation: HAL/INI syntax errors, and an error when a HAL file references an INI constant [SECTION]KEY that is not defined in the machine INI
• Multiple-writer detection on HAL signals
• Go-to-definition / find-references / highlight for HAL signals, INI variables and component pins — across all HAL files of a machine
• Hover docs for halcmd commands, component pins/params/functions, and INI keys, sourced from the LinuxCNC source
• Hovering a homing INI variable renders that section of the LinuxCNC docs
• Context-aware autocomplete: halcmd commands, loadrt component names and module parameters (incl. Mesa config=), addf functions/threads, signal names, component pins (incl. joint.N.*/axis.x.* motion pins), and [SECTION]KEY INI references — plus section/key completion inside the INI
• Custom workspace .comp components are parsed and contribute hover
• INI value checks: warns when a value doesn't match its documented type (e.g. a non-number for a real/int key) or falls outside an enum's allowed values
• G-code (.ngc): hover docs for G/M/F/S/T words (from the LinuxCNC docs), explanations for axis words, numbered/named parameters and O-word control flow, plus completion of G/M codes and O-word keywords

Open a folder containing your machine config (.ini + .hal files) for the cross-file features to work.

Multiple machines in one workspace

Cross-file features (the [SECTION]KEY check, hover, go-to-definition, completion) need to know which machine a .hal file belongs to — a machine is one .ini plus all the .hal files it pulls in via [HAL]HALFILE. Usually that mapping is unambiguous: one .ini, its own .hal files.

It gets ambiguous when the same .hal is pulled in by two or more .ini files — very common in the LinuxCNC sample configs. In configs/sim/axis, for instance, core_sim.hal is shared by axis.ini, axis_mm.ini (metric) and historical_lathe.ini. Open core_sim.hal and the extension has three candidate machines; with no pin it just uses the first one it finds.

How you'll notice

There's no popup — the symptom is wrong cross-file results in a shared .hal:

• a [SECTION]KEY reference flagged as missing even though it exists — because the value lives in the other machine's INI, not the one that was picked;
• hover / go-to-definition on an INI reference jumping to the wrong machine's value (e.g. inch vs. mm).

If a shared .hal looks wrong, that's the cue to pin the machine you actually mean.

Pinning the active machine

Run LinuxCNC: Select Active Machine from the Command Palette (Ctrl/Cmd+Shift+P):

1. it scans the workspace for machine .ini files and lists them;
2. pick the one whose context you want (or None to clear the pin);
3. it writes linuxcnc.activeMachine to your workspace .vscode/settings.json.

The server re-resolves immediately — no reload needed. You can also write the setting by hand:

// flexicam/.vscode/settings.json
{
  // The folder holds Flexicam.ini and Flexicam_qtdragon.ini, which share the
  // same .hal files. Pin the qtdragon variant as the active machine.
  "linuxcnc.activeMachine": "Flexicam_qtdragon.ini"
}

The value is matched by path suffix, so use the shortest form that's unambiguous in your workspace:

• a bare file name — "Flexicam_qtdragon.ini"
• a workspace-relative path — "configs/sim/Flexicam.ini"
• an absolute path — "/home/cnc/linuxcnc/configs/flexicam/Flexicam.ini"

Leave it empty ("") to go back to "first machine found".

What the pin does (and doesn't) do

• It's one pin per workspace, not per file. Whenever a .hal is shared, the pinned machine wins — as long as that machine actually pulls in this .hal. If the pinned machine doesn't own a given shared file, that file falls back to its first owner, so the pin never makes things worse.
• .hal files owned by exactly one machine are unaffected — pinning only matters for shared files.
• Working across machine families that don't share files? Re-run the command to switch the pin as you move between them.

Heads-up: don't use a ${workspaceFolder}/… value here. VS Code only expands ${workspaceFolder} for a few built-in settings, not third-party ones, so it would be passed through literally and match nothing. Use a plain relative path.

Credits

This is an unofficial, community extension and is not affiliated with or endorsed by the LinuxCNC project. The icon is based on the LinuxCNC application icon (linuxcnc/linuxcnc, GPL-2.0), with an added "LSP" badge.