Attention

These docs are a bit ambitious. The steps described are accurate but IronPLC cannot yet run programs.

Text

IronPLC supports plain text files containing IEC 61131-3 Structured Text (ST) programs. This is the native format for developing new IEC 61131-3 code.

File Extension

IronPLC recognizes files with the .st extension as Structured Text source files. You can also use any file extension and IronPLC will detect the format from the content.

Supported Languages

Fully Supported:

  • Structured Text (ST) - Text-based programming language

  • Sequential Function Chart (SFC) - State-machine based programming with ST action bodies

Not Supported:

  • Function Block Diagram (FBD) - Graphical language

  • Ladder Diagram (LD) - Graphical language

  • Instruction List (IL) - Deprecated text-based language

Supported Elements

IronPLC supports the following elements in Structured Text files:

Data Types:

  • Elementary types (BOOL, INT, REAL, STRING, etc.)

  • Enumeration types

  • Array types (single and multi-dimensional)

  • Structure types

  • Subrange types

  • Type aliases (derived types)

Program Organization Units:

  • Functions

  • Function Blocks

  • Programs

Configuration:

  • Configurations

  • Resources

  • Tasks

  • Program instances

SFC Elements:

  • Steps (including initial step)

  • Transitions with ST conditions

  • Actions with ST bodies

  • Action associations with qualifiers (N, R, S, L, D, P)