What is BS EN 61158-4-11 - Fieldbus specifications - Data-link layer protocol specification about?
The data-link layer provides basic time-critical messaging communications between devices in
an automation environment.
BS EN 61158-4-11 provides communication opportunities to all participating data-link entities:
In a synchronously starting cyclic manner, according to a pre-established schedule, and
In a cyclic or acyclic asynchronous manner, as requested each cycle by each of those data-link entities
BS EN 61158-4-11 can be characterized as one which provides cyclic and acyclic access asynchronously but with a synchronous restart of each cycle.
BS EN 61158-4-11 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 datalink service provider
Procedures for giving communications opportunities to all participating DL-entities, sequentially and in a cyclic manner for deterministic and synchronized transfer at cyclic intervals
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 c...