標準號：IEC 61158-5-7-2007
中文標準名稱：工業通訊網絡.數據總線規范.第5-7部分:應用層設備定義.7型元件
英文標準名稱：Industrial communication networks - Fieldbus specifications - Part 5-7: Application layer service definition - Type 7 elements
標準類型：N18;P76
發布日期：1999/12/31 12:00:00
實施日期：1999/12/31 12:00:00
中國標準分類號：N18;P76
國際標準分類號：25.040.40;35.100.70;35.160
引用標準：IEC 60559;IEC/TR 61158-1;IEC 61158-3-7;IEC 61158-4-7;ISO/IEC 7498-1;ISO/IEC 7498-3;ISO/IEC 8822;ISO/IEC 8824;ISO/IEC 9545;ISO/IEC 10731
適用范圍：1.1 OverviewThe fieldbus Application Layer (FAL) provides user programs with a means to access thefieldbus communication environment. In this respect, the FAL can be viewed as a “windowbetween corresponding application programs.”This standard provides common elements for basic time-critical and non-time-criticalmessaging communications between application programs in an automation environment. Theterm “time-critical” is used to represent the presence of a time-window, within which one ormore specified actions are required to be completed with some defined level of certainty.Failure to complete specified actions within the time window risks failure of the applicationsrequesting the actions, with attendant risk to equipment, plant and possibly human life.1.2 SpecificationsThe principal objective of this standard is to specify the characteristics of conceptualapplication layer services suitable for time-critical communications, and thus supplement theOSI Basic Reference Model in guiding the development of application layer protocols for timecriticalcommunications.A secondary objective is to provide migration paths from previously-existing industrialcommunications protocols. It is this latter objective which gives rise to the diversity of servicesstandardized as the various types of IEC 61158.This specification may be used as the basis for formal application programming interfaces.Nevertheless, it is not a formal programming interface, and any such interface will need toaddress implementation issues 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 constrainthe implementations of application layer entities within industrial automation systems.There is no conformance of equipment to this application layer service definition standard.Instead, conformance is achieved through implementation of conforming application layerprotocols that fulfill the Type 7 application layer services as defined in this standard.