DIN EN IEC 61158-3-28:2024-06

This part of IEC 61158-3-28 describes basic packet communication services and models in an automation control industrial field environment. The Type 28 data-link layer provides time-critical and non-time-critical communication services. This document defines in an abstract way the externally visible service provided by the Type 28 fieldbus data-link layer in terms of a) function description; b) primitive actions and events with primitive sequence diagram; c) the form of externally service interface and related parameters. The purpose of this document is to define the services provided to: - the Type 28 fieldbus application layer at the boundary between the application and data-link layers of the fieldbus reference model; - systems management at the boundary between the data-link layer and systems management of the fieldbus reference model. This specification can be used as the basis for formal DL-Programming-Interfaces. Nevertheless, it is not a formal programming interface, and any such interface will need to address implementation issues not covered by this specification, including: a) the sizes and octet ordering of various multi-octet service parameters; and b) the correlation of paired request and confirm, or indication and response primitives. This document does not specify individual implementations or products, nor does it constrain the implementations of data-link entities within industrial automation systems. This document can be used as a guide by developers of security layer protocols in an industrial field environment for automation control systems.