Glossary · Distributed automation and IEC 61499

Function block type

Also known as: FB type

German: Funktionsbausteintyp

In IEC 61499, a function block type defines the interface (event inputs and outputs, data inputs and outputs, and their associations) and the behavior of function blocks; the standard distinguishes basic, composite and service interface function block types.

IEC 61499
Standards

In one sentence

An IEC 61499 function block type defines the event and data interface and the behavior; types are basic, composite or service interface.

Example

A library contains the function block type E_CTU (an event-driven counter), which the application instantiates wherever parts need to be counted.

How it applies

Engineering: Types are the unit of reuse in IEC 61499. Libraries of types, including the standard event function blocks such as E_SPLIT, E_MERGE and E_CYCLE, are shared across projects. Type definitions can be exchanged as XML between tools.
Versioning: Changes to a type interface affect every instance and every connection to it. Type libraries need version control and release rules, much like Schema governance for data models.
Testing: Types are tested thoroughly once; instances are checked for correct connections and parameters.
Documentation: Each type needs reference documentation: interface, WITH associations, behavior (ECC or internal network, or service sequences for service interface blocks) and usage notes.

IEC 61499 function block type vs. IEC 61131-3 function block

An IEC 61131-3 Function block (FB) is called cyclically by a program. An IEC 61499 function block type is event-driven: it acts only when events arrive at its interface.