IEC 61158-4 Ed. 2.0被替代

The Fieldbus Data Link Layer provides basic time-critical messaging communications between devices in an automation environment.The purpose of this technical specification is to define the Fieldbus Data Link Protocol. It is most closely related to, and lies within the field of application of, the Fieldbus Data Link Service Definition.1.1 SpecificationsThis standard specifiesa) procedures for a single protocol for the timely transfer of data and control information from one data-link user entity to a peer user entity, and among the data-link entities forming the distributed data-link service provider;b) the structure of the Fieldbus Data Link (DL) Protocol Data Units used for the transfer of data and control information, and their representation as Physical Interface Data Units.The specified protocol provides communication opportunities to all participating data-link entities1) in a cyclic asynchronous manner, sequentially to each of those data-link entities, and2) in a synchronous manner, either cyclically or acyclically, according to a pre-established schedule.The specified protocol also provides means of changing the set of participating data-link entities and of modifying the set of scheduled communications opportunities. When the set of scheduled communications opportunities is null, the distribution of communication opportunities to the participating data-link entities is completely asynchronous.Thus this protocol can be characterized as one which provides access asynchronously but with a synchronous overlay.1.2 ProceduresThe procedures are defined in terms ofa) the interactions between peer DL-entities (DLEs) through the exchange of Fieldbus Data Link Protocol Data Units;b) the interactions between a DL-service (DLS) provider and a DLS-user in the same system through the exchange of DLS primitives;c) the interactions between a DLS-provider and a Physical service provider in the same system through the exchange of Physical service primitives.1.3 ApplicabilityThese procedures are applicable to instances of communication between systems which support time-critical communications services within the Data Link layer of the OSI or Fieldbus Reference Models, and which require the ability to interconnect in an open systems interconnection environment.Profiles provide a simple multi-attribute means of summarizing an implementation’s capabilities, and thus its applicability to various time-critical communications needs. Clause 10 specifies profiles for this Fieldbus protocol.1.4 ConformanceThis technical specification also specifies conformance requirements for systems implementing these procedures. This part of this technical specification does not contain tests to demonstrate compliance with such requirements.The supplier of a protocol implementation which is claimed to conform to this technical specification shall complete a copy of the PICS proforma (see annex E), and shall provide the information necessary to identify both the supplier and the implementation.

IEC 61158-4 Ed. 3.0