Introduction to CTRL

A Control program ("script") is used to control WinCC OA, and can be programmed by the actual user of the control system. In this way the user is employing a script to specify the response of WinCC OA to an event. The syntax of the internal controller language "Control" has a similar structure to that of the C programming language.

The Control program is capable of multi-program operation (multi-threading). Blocks can be defined in the CTRL script that are processed when a specific event occurs (for example, message that a data point attribute has changed). Since WinCC OA can process more than one data point at once, the Control program must also be capable of letting different processes run in parallel. The Control program must perform the following functions:

  • Control functions for technical processes

  • Enable dynamic handling of graphics objects

The Control program processes data points and controls the visualization of process states. The Control syntax is based on the procedural programming language C. Control, however, is implemented as an interpreter, so that the user does not have to perform compiling or linking. This means that changes can be tested immediately. Control provides optimum support for the flexible data point concept of WinCC OA.

Anmerkung: Only special characters from the iso88591 character set can be used in CTRL scripts. Special characters within variable names are not permitted.