IEC 61158-4-8:2007 provides a highly-optimized means of interchanging fixed-length input/output data and variable-length segmented messages between a single master device and a set of slave devices interconnected in a loop (ring) topology. The exchange of input/output data is totally synchronous by configuration, and is unaffected by the messaging traffic. Devices are addressed implicitly by their position on the loop. The determination of the number, identity and characteristics of each device can be configured, or can be detected automatically at start-up. This first edition and its companion parts of the IEC 61158-4 subseries cancel and replace IEC 61158-4:2003. It constitutes an editorial revision and includes the following significant 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. This bilingual version corresponds to the monolingual English version, published in 2007-12.