Introduction - Structured Text (ST)



Ladder Logic

RSLogix 5000

Structured Text






Welcome to the Structured Text training. We have worked very hard to make this document very easy and simple to understand to new programmers. Structured Text programmers guide is a comprehensive manual on programming with Structured Text

Structured Text

Structured Text programming is very powerful language. If you can do it in Ladder Logic or Function Block or any other language, then it can probably be accomplished using Structured Text. As you might guess, there is a lot to be learned before you can consider yourself a guru; but once you understand the basics of Structured Text you will find that you are very productive in no time at all.

Language Basics

Even a small program in Structured Text uses many of the traditional features of high-level language including variables, operators, and control flow statements. The code might look a little mysterious for programmers who have no knowledge in High-Level programming for now. But this trail teaches what you need to know about the nuts and bolts of the Text Structure programming language.

  • Variables : Variables in Structured Text program are used to hold data.
  • Operators : such as arithmetic and assignment operations.
  • Expressions : Is a combination of operators and variables into sequences known as expressions. Expressions are the building blocks of your code.
  • Control Flow : Programs use control flow statements to conditionally execute statements, to loop over statements, or to jump to another area in the program.

Structured Text Learning Curve

Structured Text is the fastest and easiest way to create programs in controllers. Whether you are an experienced professional or brand new to PLC programming, Structured Text provides you with a complete set of tools to simplify rapid program development.

So what is Structured Text? The "Structured" part refers to the high level programming capabilities and "Text" refers to the ability to used text instead of symbols as in Ladder Logic, Function Block and Sequential Function Chard. If you've ever used any high level language such as basic, Pascal or C then you will most probably have the skills to create simple program without any difficulties in any time.

Like any other high level language Structured Text contains many functions, and keywords, many of which are to do equivalent functions as in the other languages. Beginners can create useful applications by learning just a few of the keywords, yet the power of the language allows professionals to accomplish anything that can be accomplished using any other language.

Whether your goal is to create a small function or to develop large and sophisticated automation programs Structured Text programming language has the tools you need. The existence of Structured Text Language is not to replace any of the other languages. Each language has it's own advantages and disadvantages. One of the main advantages in Structured Text is its ability to simplify complex mathematical equations.

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PLC Languages

Ladder Logic
Function Block
Structure Text

Ladder Logic

Trig Functions






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