1.1 General
The data-link layer provides basic time-critical messaging communications between devices in
an automation environment.
This protocol provides communication opportunities to all participating data-link entities
a) in a synchronously-starting cyclic manner, according to a pre-established schedule, and
b) in a cyclic or acyclic asynchronous manner, as requested each cycle by each of those
data-link entities.
Thus this protocol can be characterized as one which provides cyclic and acyclic access
asynchronously but with a synchronous restart of each cycle.
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 datalink
service provider;
b) procedures for giving communications opportunities to all participating DL-entities,
sequentially and in a cyclic manner for deterministic and synchronized transfer at cyclic
intervals up to one millisecond;
c) procedures for giving communication opportunities available for time-critical data
transmission together with non-time-critical data transmission without prejudice to the
time-critical data transmission;
d) procedures for giving cyclic and acyclic communication opportunities for time-critical data
transmission with prioritized access;
e) procedures for giving communication opportunities based on standard ISO/ IEC 8802-3
medium access control, with provisions for nodes to be added or removed during normal
operation;
f) 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.
IEC 61158-4-14:2007 history
2014IEC 61158-4-14:2014 Industrial communication networks - Fieldbus specifications - Part 4-14: Data-link layer protocol specification - Type 14 elements
2010IEC 61158-4-14:2010 Industrial communication networks - Fieldbus specifications - Part 4-14: Data-link layer protocol specification - Type 14 elements
2007IEC 61158-4-14:2007 Industrial communication networks - Fieldbus specifications - Part 4-14: Data-link layer protocol specification - Type 14 elements