標準號：DIN EN 61158-3-7-2008
中文標準名稱：工業通訊網絡.現場總線規范.第3-7部分:數據聯絡層設備定義.7型元件.僅為CD-ROM
英文標準名稱：Industrial communication networks - Fieldbus specifications - Part 3-7: Data-link layer service definition - Type 7 elements (IEC 61158-3-7:2007); English version EN 61158-3-7:2008, only on CD-ROM
標準類型：N18;P76
發布日期：1999/12/31 12:00:00
實施日期：2008/9/1 12:00:00
中國標準分類號：N18;P76
國際標準分類號：35.100.20;35.160;35.240.50
引用標準：ISO/IEC 7498-1;ISO/IEC 7498-3;ISO/IEC 10731
適用范圍：1.1 OverviewThis part of IEC 61158 provides common elements for basic time-critical messagingcommunications between devices in an automation environment. The term “time-critical” is used torepresent the presence of a time-window, within which one or more specified actions are required tobe completed with some defined level of certainty. Failure to complete specified actions within thetime window risks failure of the applications requesting the actions, with attendant risk toequipment, plant and possibly human life.This standard defines in an abstract way the externally visible service provided by the Type 7fieldbus data-link layer in terms ofa) the primitive actions and events of the service;b) the parameters associated with each primitive action and event, and the form which they take;andc) the interrelationship between these actions and events, and their valid sequences.The purpose of this standard is to define the services provided to? the Type 7 fieldbus application layer at the boundary between the application and data-linklayers of the fieldbus reference model, and? systems management at the boundary between the data-link layer and systems management ofthe fieldbus reference model.1.2 SpecificationsThe principal objective of this standard is to specify the characteristics of conceptual data-link layerservices suitable for time-critical communications, and thus supplement the OSI Basic ReferenceModel in guiding the development of data-link protocols for time-critical communications. Asecondary objective is to provide migration paths from previously-existing industrialcommunications protocols.This specification may be used as the basis for formal DL-Programming-Interfaces. Nevertheless, itis not a formal programming interface, and any such interface will need to address implementationissues not covered by this specification, includinga) the sizes and octet ordering of various multi-octet service parameters, andb) the correlation of paired request and confirm, or indication and response, primitives.1.3 ConformanceThis standard does not specify individual implementations or products, nor does it constrain theimplementations of data-link entities within industrial automation systems.There is no conformance of equipment to this data-link layer service definition standard. Instead,conformance is achieved through implementation of the corresponding data-link protocol that fulfillsthe Type 7 data-link layer services defined in this standard.