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IronPLC - Open-Source IEC 61131-3 Toolchain
IronPLC - Open-Source IEC 61131-3 Toolchain
  • Quick start
    • Installation
    • How a PLC Program Works
    • Your First Program
    • Configuring Your Application
    • Working with Multiple Files
    • Connecting to Hardware
  • How-to guides
    • Getting Started
      • Check, Compile, and Run from the CLI
      • Structure a Multi-File Project
      • Read Compiler Error Messages
    • Coming from Beremiz
      • Check Beremiz Projects
    • Coming from TwinCAT
      • Check TwinCAT 3 Projects
    • Using AI Agents
      • Write PLC Programs with an AI Agent
    • Update IronPLC on your computer
    • Troubleshoot the Editor Extension
  • Explanation
    • What is IEC 61131-3?
    • IronPLC and the IEC 61131-3 Ecosystem
    • Structured Text Basics
    • Program Organization
    • Execution Cycle
    • Variables and I/O
    • System Clock and Uptime
    • References and Indirection
    • Type Conversions
    • Enabling Dialects and Features
  • Reference
    • Language
      • Edition Support
      • Data Types
        • BOOL
        • SINT
        • INT
        • DINT
        • LINT
        • USINT
        • UINT
        • UDINT
        • ULINT
        • REAL
        • LREAL
        • BYTE
        • WORD
        • DWORD
        • LWORD
        • STRING
        • WSTRING
        • TIME
        • LTIME
        • DATE
        • LDATE
        • TIME_OF_DAY
        • LTIME_OF_DAY
        • DATE_AND_TIME
        • LDATE_AND_TIME
        • Enumerated Types
        • Subrange Types
        • Array Types
        • Structure Types
        • Reference Types
      • Variables
        • Variable Declarations
        • I/O Qualifiers
        • Variable Scope
        • Retention
        • Initial Values
      • Program Organization Units
        • PROGRAM
        • FUNCTION
        • FUNCTION_BLOCK
        • CONFIGURATION
        • RESOURCE
        • TASK
      • Structured Text
        • Assignment
        • Bit Access
        • IF
        • CASE
        • FOR
        • WHILE
        • REPEAT
        • EXIT
        • RETURN
        • Arithmetic Operators
        • Comparison Operators
        • Logical Operators
        • Function Call
      • Ladder Diagram
        • Rungs
        • Contacts
        • Coils
        • Branches
    • Standard Library
      • Functions
        • ABS
        • SQRT
        • LN
        • LOG
        • EXP
        • EXPT
        • SIN
        • COS
        • TAN
        • ASIN
        • ACOS
        • ATAN
        • ADD
        • SUB
        • MUL
        • DIV
        • MOD
        • MOVE
        • GT
        • GE
        • EQ
        • LE
        • LT
        • NE
        • SEL
        • MAX
        • MIN
        • LIMIT
        • MUX
        • SHL
        • SHR
        • ROL
        • ROR
        • LEN
        • LEFT
        • RIGHT
        • MID
        • CONCAT
        • INSERT
        • DELETE
        • REPLACE
        • FIND
        • ADD_TIME
        • SUB_TIME
        • MUL_TIME
        • DIV_TIME
        • ADD_DT_TIME
        • ADD_TOD_TIME
        • SUB_DT_TIME
        • SUB_TOD_TIME
        • SUB_DT_DT
        • SUB_DATE_DATE
        • SUB_TOD_TOD
        • CONCAT_DATE_TOD
        • DT_TO_DATE
        • DT_TO_TOD
        • Type Conversions
        • TRUNC
        • BCD_TO_INT / INT_TO_BCD
      • Function Blocks
        • TON
        • TOF
        • TP
        • CTU
        • CTD
        • CTUD
        • R_TRIG
        • F_TRIG
        • SR
        • RS
    • Extension Library
      • Functions
        • SIZEOF
      • Function Blocks
      • Variables
        • System Uptime
    • Compiler
      • Overview
      • Command Reference
      • Source Formats
        • Text
        • PLCopen XML
        • TwinCAT
      • Problem Code Index
        • P0001
        • P0002
        • P0003
        • P0004
        • P0005
        • P0006
        • P0007
        • P0008
        • P0009
        • P0010
        • P0011
        • P2001
        • P2002
        • P2003
        • P2004
        • P2005
        • P2006
        • P2007
        • P2008
        • P2009
        • P2010
        • P2011
        • P2012
        • P2013
        • P2014
        • P2015
        • P2016
        • P2017
        • P2019
        • P2020
        • P2021
        • P2022
        • P2023
        • P2024
        • P2025
        • P2026
        • P2027
        • P2028
        • P2029
        • P2030
        • P2031
        • P2032
        • P2033
        • P2034
        • P2035
        • P2036
        • P4001
        • P4002
        • P4003
        • P4004
        • P4005
        • P4006
        • P4007
        • P4008
        • P4009
        • P4010
        • P4011
        • P4012
        • P4013
        • P4014
        • P4015
        • P4016
        • P4017
        • P4018
        • P4019
        • P4020
        • P4021
        • P4022
        • P4023
        • P4024
        • P4025
        • P4026
        • P4027
        • P4028
        • P4029
        • P4030
        • P4031
        • P4032
        • P4033
        • P6001
        • P6002
        • P6003
        • P6004
        • P6005
        • P6006
        • P6007
        • P6008
        • P8001
        • P9001
        • P9002
        • P9003
        • P9998
        • P9999
    • Runtime
      • Overview
      • Command Reference
      • Problem Code Index
        • V4001
        • V4002
        • V4003
        • V4004
        • V4005
        • V6001
        • V6002
        • V6003
        • V6004
        • V6005
        • V6006
        • V6007
        • V9001
        • V9002
        • V9003
        • V9004
        • V9005
        • V9006
        • V9007
        • V9008
        • V9009
        • V9010
        • V9011
        • V9012
        • V9013
    • MCP Server
      • Overview
      • Command Reference
      • Tool Reference
    • Editor Extension
      • Overview
      • Build Tasks
      • Bytecode Viewer
      • Settings
      • Problem Code Index
        • E0001
        • E0002
        • E0003
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IronPLC¶

IronPLC is a compiler, runtime, Visual Studio Code editor extension, and MCP server for writing and running IEC 61131-3 programs. IronPLC reads Structured Text, PLCopen XML and other vendor files directly, so you can use IronPLC alongside your existing PLC development environment.

VS Code showing an IEC 61131-3 Structured Text file with syntax highlighting

Structured Text with syntax highlighting in Visual Studio Code.¶

IronPLC supports most of IEC 61131-3 edition 2 and parts of edition 3 but doesn’t yet provide I/O mapping or debugging capabilities. Still, there is plenty you can do with IronPLC today including running code using the IronPLC Playground, authoring code with an AI agent using IronPLC’s Model Context Protocol (MCP) server, and running applications locally.

IronPLC is free (subject to MIT license terms) and works on Windows, macOS and Linux.

Tutorials

New to IEC 61131-3 or IronPLC? Start here with a step-by-step guide that builds up from nothing.

Quick start tutorial
How-to guides

Practical guides for specific tasks — whether you are getting started, coming from Beremiz, or coming from TwinCAT.

How-to guides
Explanation

Understand the concepts behind IEC 61131-3: the scan cycle, program organization, Structured Text, and how I/O works.

Explanation
Reference

Technical reference for the compiler, editor extension, and runtime.

Reference
Playground

Try IronPLC in your browser — no installation needed. Write, compile, and run IEC 61131-3 programs directly in the IronPLC Playground.

https://playground.ironplc.com
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Quick start tutorial
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