ISA 50.02, Part 3 – Fieldbus Standard for Use in Industrial Control Systems – Part 3: Data Link Service Definition
Formerly S50.01, Part 3-1997. Specifies a) the procedures for a single protocol 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 b) the structure of the Fieldbus Data Link (DL) Protocol Data Units used for the transfer of data and control information, and their representation as Physical Interface Data Units.