EN 61158-4-8:2008

FOREWORD
INTRODUCTION
1 Scope
  1.1 General
  1.2 Specifications
  1.3 Procedures
  1.4 Applicability
  1.5 Conformance
2 Normative references
3 Terms, definitions, symbols and abbreviations
  3.1 Reference model terms and definitions
  3.2 Service convention terms and definitions
  3.3 Common terms and definitions
  3.4 Additional Type 8 definitions
  3.5 Symbols and abbreviations
4 DL-protocol
  4.1 Overview
  4.2 DL-service Interface (DLI)
  4.3 Peripherals data link (PDL)
  4.4 Basic Link Layer (BLL)
  4.5 Medium Access Control (MAC)
  4.6 Peripherals network management for layer 2 (PNM2)
  4.7 Parameters and monitoring times of the DLL
Annex A (informative) - Implementation possibilities of
        definite PNM2 functions
  A.1 Acquiring the current configuration
  A.2 Comparing the acquired and stored configurations
      prior to a DL-subnetwork error
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 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. 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.