5 Understanding Programming
5-8
CJ2 CPU Unit Software User’s Manual
The ST (Structured Text) language is a high-level language code for industrial controls (mainly PLCs)
defined by the IEC 61131-3 standard. The standard control statements, operators, and functions make
the ST language ideal for mathematical processing that is difficult to write in ladder programming. (The
ST language does not support all of the processing that can be written in ladder diagrams. The ST lan-
guage that conforms to the IEC 61131-3 standard is supported.
Additional Information
For details on ST programming specifications, notation, and input procedures, refer to the CX-
Programmer Operation Manual: Function Blocks and Structured Text (Cat. No. W447).
z Features of ST Programming
• There are many control statements available, such as loop statements and IF-THEN-ELSE state-
ments, many operators such as arithmetic operators, comparison operators, and AND/OR opera-
tors, as well as many mathematical functions, string extract and merge functions, Memory Card
processing functions, string transfer functions, and trigonometric functions.
• Programs can be written like high-level languages such as C, and comments can be included to
make the program easy to read.
• ST programs can be uploaded and downloaded just like ordinary programs, but ST program tasks
cannot be uploaded and downloaded in task units.
• Function blocks (ladder or ST language) can be called in ST programs.
• One-dimensional array variables are supported for easier data handling in applications.
z Specifications
5-1-3 ST Language
Item Specification
ST program units • Tasks
• Algorithms for function block definitions
• Action programs and transition programs in SFCs.
Address specifying procedure Addresses are specified using symbols. Any address can be assigned to the
symbol.
Force-setting and force-resetting Supported.
Online editing ST program editing
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