At the highest level, all the software needed to solve a particular control problem can be formulated as a Configuration. A special configuration for a particular type of control systems, including hardware setup, namely the processing resources, memory addresses for I / O channels and system capabilities.
In one configuration can specify one or more resources. One can view the resource as a processing facility that can be used to execute IEC programs. In resources, one or more tasks can be defined. Control task execution of a program to set and / or function blocks. This can be done periodically or upon the occurrence of certain triggers, such as a change of variables.
The program is built from a number of different software elements written in one language that defined the IEC. Typically, the program consists of a network of Functions and Function Blocks, capable of exchanging data. Functions and Function Blocks are the basic building block, which contains data structures and algorithms.
Let us compare this to the conventional PLC: This contains about resources, running one task, controlling one program, walking is a closed loop. IEC 61131-3 adds much to this, so open for the future. Future that includes a multi-processing and event-driven program