DIN EN 61158-4-8-2008 工业通讯网络.现场总线规范.第4-8部分:数据联络层协议规范.8型元件.仅为CD-ROM
Industrial communication networks - Fieldbus specifications - Part 4-8: Data-link layer protocol specification - Type 8 elements (IEC 61158-4-8:2007); English version EN 61158-4-8:2008, only on CD-ROM
1.1 General
The data-link layer provides basic time-critical messaging communications between devices in an
automation environment.
This protocol provides a highly-optimized means of interchanging fixed-length input/output data and
variable-length segmented messages between a single master device and a set of slave devices
interconnected in a loop (ring) topology. The exchange of input/output data is totally synchronous
by configuration, and is unaffected by the messaging traffic.
Devices are addressed implicitly by their position on the loop. The determination of the number,
identity and characteristics of each device can be configured, or can be detected automatically at
start-up.
1.2 Specifications
This standard specifies
a) procedures 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 DLPDUs used for the transfer of data and control information by the
protocol of this standard, and their representation as physical interface data units.
1.3 Procedures
The procedures are defined in terms of
a) the interactions between peer DL-entities (DLEs) through the exchange of fieldbus DLPDUs;
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 Ph-service provider in the same system through
the exchange of Ph-service primitives.
1.4 Applicability
These 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.
1.5 Conformance
This standard also specifies conformance requirements for systems implementing these
procedures. This standard does not contain tests to demonstrate compliance with such
requirements.