IEC 61158-4-24:2023 provides
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 datalink service provider;
procedures for giving communications opportunities to all participating DL-entities (DLEs), sequentially and in a cyclic manner for deterministic and synchronized transfer at cyclic intervals up to 64 ms;
procedures for giving communication opportunities available for time-critical data transmission together with non-time-critical data transmission without prejudice to the time-critical data transmission;
procedures for giving cyclic and acyclic communication opportunities for time-critical data transmission with prioritized access;
procedures for giving communication opportunities based on ISO/IEC/IEEE 8802‑3 medium access control, with provisions for nodes to be added or removed during normal operation;
the structure of the fieldbus DLPDUs used for the transfer of data and control information by the protocol of this document, and their representation as physical interface data units.
