IEC/PAS 61158-4-22
Industrial communication networks – Fieldbus specifications – Part 4–22: Data-link layer protocol specification – Type SNpTYPE elements
| Organization: | IEC |
| Publication Date: | 1 August 2009 |
| Status: | inactive |
| Page Count: | 70 |
| ICS Code (Industrial automation systems): | 25.040 |
| ICS Code (Data link layer): | 35.100.20 |
scope:
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
in a synchronously-starti
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.
Specifications
This part of IEC 61158-4 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) the structure of the fieldbus DLPDUs used for the transfer of data and control information by the protocol of this part of IEC 61158-4, and their representation as physical interface data units.
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.
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.
Conformance
This part of IEC 61158-4 also specifies conformance requirements for systems implementing these procedures.
This part of IEC 61158-4 does not contain tests to demonstrate compliance with such requirements.
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