1 Scope
1.1 General
The data-link layer provides several types of messaging communications between devices
in an automation environment.
This part of IEC 61158 provides a means of connecting devices through a partial mesh network, such that
most failures of an interconnection between two devices can be circumvented. In common
practice, the devices are interconnected in a non-redundant hierarchical manner reflecting
application needs.
1.2 Specifications
This document specifies
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;
the structure of the fieldbus DLPDUs used for the transfer of data and control information
by the protocol of this document, and their representation as physical interface data
units.
1.3 Procedures
The procedures are defined in terms of