IEC 61131-3

IEC 61131-3 language support for Visual Studio Code — syntax highlighting and language configuration for IEC 61131-3 source files.

Features

• Syntax Highlighting — supports .iec, .st, .iecst files
  • Control flow keywords (if/end_if, for/end_for, case/end_case, etc.)
  • POU declarations (function, function_block, program, method, class, etc.)
  • Variable section keywords (var, var_input, var_output, var_in_out, etc.)
  • Data types (bool, byte, char, date_and_time, dint, dt, int, ldate_and_time, ldt, lint, lreal, string, time, wchar, wstring, etc.)
  • Duration literals (e.g. t#1h30m, time#500ms)
  • Date/time literals (e.g. d#2024-01-01, tod#12:00:00)
  • Numeric literals (decimal, hex 16#, binary 2#, octal 8#)
  • Direct addresses (e.g. %ix0.0, %qw1, %md2)
  • Operators (:=, ?=, &, or, not, mod, xor, etc.)
  • Line comments (//) and block comments ((*..*), /*..*/)
  • Pragmas ({...})
  • Single-quoted and double-quoted strings with $-escape sequences
• Language Configuration
  • Bracket matching for () and []
  • Auto-closing pairs for (), [], (**), /**/, '', ""
  • Indentation rules for ST block keywords (if/end_if, etc.)
  • Comment toggle with // (line) and (*..*) (block)

Example

{This is a pragma}
function_block Counter
var_input
    Enable : bool;
    Step   : dint := 1;
end_var
var_output
    Value  : dint;
end_var
var
    _initialized : bool := false;
end_var

if not _initialized then
    Value := 0;
    _initialized := true;
end_if;

if Enable then
    Value := Value + Step;
end_if;

end_function_block

Supported File Extensions

Installation

Install from the VS Code Marketplace, or install a .vsix file directly.

Local Development

Clone the repository and press F5 to launch the Extension Development Host:

git clone https://github.com/yunos0987/vscode-iec-61131-3-lang.git
cd vscode-iec-61131-3-lang
code .
# Then press F5 in VS Code

Alternatively, install a packaged .vsix:

code --install-extension iec-61131-3-<version>.vsix

License

MIT License

Changelog

See CHANGELOG.md.

Related Resources

• jiecc — An IEC 61131-3 converter. Converts IEC 61131-3 source code to IEC 61131-10 XML into a format importable by each manufacturer's PLC tool (Beckhoff TwinCAT, CODESYS, OMRON, Mitsubishi, etc.).

• jieclib — An IEC 61131-3 source code library. Real-world .iec files you can open directly to see this extension's syntax highlighting in action.