Attention

IronPLC can only run very simple programs. The steps described are accurate but many language features are not yet supported.

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 Extensions

IronPLC recognizes files with the .st or .iec extension as Structured Text source files.

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

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)