EN 61158-4-17:2008

FOREWORD
INTRODUCTION
1 Scope
  1.1 General
  1.2 Specifications
  1.3 Procedures
  1.4 Applicability
  1.5 Conformance
2 Normative reference
3 Definitions
  3.1 Terms and definitions
  3.2 Abbreviations and symbols
  3.3 Conventions
4 Overview of the DL-protocol
  4.1 General
  4.2 Characteristics of the protocol
  4.3 Data-link layer architecture
  4.4 Services provided by the DLL
  4.5 Network sharing with other protocols
5 DLPDU-parameter structure and encoding
  5.1 Overview
  5.2 DLPDU common header format
  5.3 DLPDU body format
6 Local parameters and resources
  6.1 General
  6.2 Parameters and resources related to network structure
  6.3 Parameters and resources to support real-time
      data transfer
  6.4 Parameters and resources to support the scheduling
      function
  6.5 Parameters and resources to support the security
      function
7 DL-service elements of procedure
  7.1 Unacknowledged unitdata transfer service (UUS)
  7.2 Acknowledged unitdata transfer service (AUS)
  7.3 Acknowledged sequence of unitdata transfer service
      (ASS)
  7.4 Multipoint unitdata transfer service (MUS)
  7.5 Multipoint sequence of unitdata transfer service (MSS)
8 DL-support protocol
  8.1 Transmission scheduling
  8.2 Redundancy
  8.3 DLPDU authentication
Annex ZA (normative) Normative references to international
         publications with their corresponding European
         publications
Bibliography

It 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 cyclic asynchronous manner, sequentially to each of those data-link entities, and 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. It includes the following significant changes with respect to the previous edition deletion of the former Type 6 fieldbus, and the placeholder for a Type 5 fieldbus data-link layer, for lack of market relevance; addition of new types of fieldbuses; division of this part into multiple parts numbered.