IEC 61158-4-7:2007 describes the data-link layer which provides basic time-critical messaging communications between devices in an automation environment. It specifies the 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. This first edition and its companion parts of the IEC 61158-4 subseries cancel and replace IEC 61158-4:2003 and constitutes an editorial revision. It includes the following changes:
– 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 -4 1, -4 2,…, -4-19. This bilingual version (2013-09) corresponds to the monolingual English version, published in 2007-12.