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
IEC 61499功能塊能實現這種完全的分散式IPMCS,其關鍵在於採用軟體組件(software component)技術設計功能塊。組件是獨立於特定程式設計語言和套用系統、可重用和自包含的軟體成分。組件技術是基於面向對象的、支持拖放(drog and drop)和即插即用(plug and play)的軟體開發概念。基於組件技術的開發方法,具有開放型、易升級、易維護等優點。主要有CORBA、COM和JavaBeans[2]三種組件技術規範,具體實現時可自由選擇。IEC 61499功能塊是健壯的、可重用的軟體組件,一個功能塊提供對特定問題的解決方法,例如對閥的控制,或控制工廠的主體單元(如整條生產線)。系統設計者構建分散式控制系統時,根據控制功能需要選擇特定功能塊,並按照IEC 61499標準將它們進行軟體互連,設計靈活,且系統可伸縮、可變形。可預見將來的工業控制器和儀表可把功能塊作為設備固件的一部分,或從功能塊庫里選擇下載,而系統設計將成為功能塊選擇、組態和互連的簡單工作。