Structured Text (ST) Programming Language

Structured Text (ST) is a text-based, high-level programming language defined in the IEC 61131-3 standard.

It is designed for writing complex algorithms and control flows, similar to traditional programming languages.

Key Features:

• Supports conditional statements like: IF…THEN…ELSE
• Supports looping constructs: WHILE…DO, FOR…TO

Expressions – An expression returns a value after evaluation

Composed of:

• Operators (e.g., +, -, AND, OR)
• Operands (constants, variables, function calls, or other expressions)

Expression Evaluation:

• Follows operator binding rules:
  • Operators with higher precedence are evaluated first
  • Operators with the same precedence are evaluated left to right