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.