ISPSoft User Manual

ISPSoft User Manual
11.1 Knowing Structured Texts
A structured text is a high level language that is syntactically resembles C or Pascal. It is composed
of text. Compared with instruction lists, structured texts are more readable. A structured text is very
flexible and intuitive for writing control algorithms. People who are trained in programming
languages often find it the easiest language to use for programming control logic. Besides,
structured texts provide a familiar programming environment for programmers who are familiar with
the C language.
11.1.1 Basic Structure of a Structured Text
The structured text shown below is a basic structured text. It has the same function as the ladder
diagram under it. The structure of the structured text is similar to the syntax of human language. A
structured text is composed of statements.
The structure of the structured text above is shown below.
* In a structured text, “:=” means “to assign”, and “=” means “to be equal to”.
11.1.2 Statement
The statement is a basic unit. It represents a complete task which can be executed. A complete
statement may not be represented by a single line, but it always ends with a semicolon.
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