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The international standard IEC 61499, addressing the topic of function blocks for industrial process measurement and control systems, was initially published in 2005. The specification of IEC 61499 defines a generic model for distributed control systems and is based on the IEC 61131 standard. The concepts of IEC 61499 are also explained by Lewis and Zoitl 〔Alois Zoitl and Robert Lewis: Modeling control systems using IEC 61499, Applying function blocks to distributed systems, Control Engineering Series 59, The Institution of Electrical Engineers, London July 2001.〕 as well as Vyatkin.〔Valeriy Vyatkin: IEC 61499 Function Blocks for Embedded and Distributed Control Systems Design, Instrumentation Society of America, USA, 2006, 2011 (second edition), 2014 (third edition in German and English)〕 == Part 1: Architecture == IEC 61499-1 defines the architecture for distributed systems. In IEC 61499 the cyclic execution model of IEC 61131 is replaced by an event driven execution model. The event driven execution model allows an explicit specification of the execution order of function blocks. If necessary, periodically executed applications can be implemented by using the E_CYCLE function block for the generation of periodic events as described in Annex A of IEC 61499-1. IEC 61499 enables an ''application-centric'' design, in which one or more applications, defined by networks of interconnected function blocks, are created for the whole system and subsequently distributed to the available devices. All devices within a system are described within a ''device model''. The topology of the system is reflected by the ''system model''. The distribution of an application is described within the ''mapping model''. Therefore, applications of a system are distributable but maintained together. Like IEC 61131-3 function blocks, IEC 61499 function block types specify both an interface and an implementation. In contrast to IEC 61131-3, an IEC 61499 interface contains ''event'' inputs and outputs in addition to ''data'' inputs and outputs. Events can be associated with data inputs and outputs by ''WITH constraints''. IEC 61499 defines several function block types, all of which can contain a behavior description in terms of service sequences: * Service interface function block – SIFB: The source code is hidden and its functionality is only described by service sequences. * Basic function block - BFB: Its functionality is described in terms of an Execution Control Chart (ECC), which is similar to a state diagram (UML). Every state can have several actions. Each action references one or zero algorithms and one or zero events. Algorithms can be implemented as defined in compliant standards. * Composite function block - CFB: Its functionality is defined by a function block network. * Adapter interfaces: An adapter interface is not a real function block. It combines several events and data connections within one connection and provides an interface concept to separate specification and implementation. * Subapplication: Its functionality is also defined as a function block network. In contrast to CFBs, subapplications can be distributed. To maintain the applications on a device IEC 61499 provides a ''management model''. The ''device manager'' maintains the lifecycle of any resource and manages the communication with the software tools (e.g., configuration tool, agent) via ''management commands''. Through the interface of the software tool and the management commands, online reconfiguration of IEC 61499 applications can be realized.〔Alois Zoitl Real-Time Execution for IEC 61499, Instrumentation Society of America (ISA), USA, ISBN 978-1934394274, November 2008.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「IEC 61499」の詳細全文を読む スポンサード リンク
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