The Standard

The IEC 61499 Standard defines an open architecture for the next generation of distributed control and automation.

This architecture represents a light-weight component solution that provides essential features such as encapsulation of semantics from a particular platform, portability, reconfiguration and a holistic view on distributed applications. As the standard is designed for the development of distributed systems, it further supports features like reusability and interoperability.

The IEC 61499 Standard provides a generic model for distributed systems. This model includes processes and communication networks as an environment for embedded devices, resources and applications.

Applications are built by networks of Function Blocks. The Function Block is the elementary model of the IEC 61499 Standard. A Function Block generally provides an Interface for Event I/O’s and Data I/O’s.

There are two types of Function Blocks. Basic Function Blocks on the one hand and Composite Function Blocks on the other. A Composite Function Block can contain other Composite Function Blocks and/or Basic Function Blocks. Thus, Composite Function Blocks enable modular design methodologies.

Basic Function Blocks include event-driven Execution Control Charts (abbr. ECC), which are similar to state machines. The elements of the ECC are states and event-triggered transitions. An ECC can trigger the execution of Algorithms by the occurrence of events.

An executed algorithm produces new output data from the input data. When the algorithm has finished, an output event is generated. But Output events can also be emitted without the execution of algorithms. Output events might be the input events for other Function Blocks.

IEC 61499 provides:

Generic modeling approach for distributed control applications

Function Block concept

Separation of data and event flow