Structured Text Overview
What is Structured Text? Structured Text (ST) is a high-level programming language defined in the IEC 61131-3 standard for programmable logic controllers (PLCs) and other industrial automation systems.
🚀 Enhance Your Development Experience
Get the most out of Structured Text programming with our VS Code extension:
Install VS Code Extension →Why Structured Text?
Structured Text brings the power and flexibility of modern programming languages to industrial automation. Unlike traditional ladder logic, ST offers:
- Readability: Code that clearly expresses complex logic and algorithms
- Maintainability: Easier debugging, testing, and code reuse
- Scalability: Better suited for large, complex control applications
- Modularity: Support for functions, function blocks, and structured programming
- Standard Compliance: Follows IEC 61131-3 for cross-platform compatibility
Modern Industrial Automation
Today's industrial systems demand sophisticated control logic that can handle:
🏭 Complex Processes
Multi-step manufacturing processes, batch control, and coordinated machine operations require algorithmic thinking that ST naturally supports.
📊 Data Processing
Modern automation involves significant data manipulation, calculations, and communication with enterprise systems.
🔗 System Integration
Integration with databases, web services, and IoT devices requires flexible programming approaches.
🛠️ Code Reusability
Structured Text's function and function block capabilities enable creating reusable, tested code libraries.
IEC 61131-3 Standard
The IEC 61131-3 standard defines five programming languages for industrial automation:
Structured Text in Context
While IEC 61131-3 includes Ladder Diagram (LD), Function Block Diagram (FBD), Sequential Function Chart (SFC), and Instruction List (IL), Structured Text stands out for:
- Mathematical and algorithmic operations
- Complex conditional logic
- String manipulation and data processing
- Implementation of advanced control algorithms
See It In Action
Experience Structured Text development with the ControlForge VS Code extension. This interactive demo shows real syntax highlighting and features:
PROGRAM MainProgram
VAR
Counter: INT := 0;
Timer1: TON;
StartButton: BOOL;
StopButton: BOOL;
MotorRunning: BOOL;
END_VAR
// Main program logic
IF StartButton AND NOT StopButton THEN
MotorRunning := TRUE;
Counter := Counter + 1;
ELSIF StopButton THEN
MotorRunning := FALSE;
Counter := 0;
END_IF;
// Timer example
Timer1(IN := MotorRunning, PT := T#5s);
IF Timer1.Q THEN
// Timer elapsed - perform action
Counter := 0;
END_IF;
END_PROGRAMGetting Started
Ready to dive into Structured Text programming? This documentation covers everything you need:
Syntax Basics
Learn the fundamental syntax rules and structure
Variables & Types
Understand data types and variable declarations
Control Structures
Master IF, CASE, FOR, WHILE, and REPEAT