IEC 61158-4-2:2014

IEC 61158-4-2:2010 provides communication opportunities to all participating data-link entities, sequentially and in a cyclic synchronous manner. Foreground scheduled access is available for time-critical activities together with background unscheduled access for less critical activities. It provides means to maintain clock synchronization across an extended link with a precision better than 10 ms. This protocol optimizes each access opportunity by concatenating multiple DLSDUs and associated DLPCI into a single DLPDU, thereby improving data transfer efficiency for data-link entities that actively source multiple streams of data. This second edition cancels and replaces the first edition published in 2007 and constitutes a technical revision. The main changes with respect to the previous edition are: - update of normative and bibliographic references; - update of abbreviations; - updates of the Ethernet Link object; - new DLR and QoS objects; - new DLR protocol. This bilingual version (2012-07) corresponds to the monolingual English version, published in 2010-08.

IEC 61158-4-2:2019 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 and the structure of the fieldbus DLPDUs used for the transfer of data and control information by the protocol of this standard, and their representation as physical interface data units. This fourth edition cancels and replaces the third edition published in 2014 and constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: ?clarifications of ControlNet object in 7.2; ?extensions and clarifications of TCP/IP interface object in 7.5; ?extensions and clarifications of Ethernet Link object in 7.6; ?clarifications of DeviceNet object in 7.7; ?extensions and clarifications of CCO object in 7.8; ?extensions and clarifications of DLR object in 7.9; ?extensions and clarifications of Port object in 7.11; ?addition of PRP/HSR Protocol and PRP/HSR Nodes Table objects in 7.12 and 7.13; ?extensions and clarifications of DLR protocol in Clause 10; ?addition of PRP/HSR protocol mapping in Clause 11; ?update of indicator behaviour in A.2.2 and A.2.4; ?miscellaneous editorial corrections.