The data-link layer provides basic time-critical messaging communications between devices in
an automation environment.
This protocol provides communication opportunities to all participating data-link entities
a) in a synchronously-starting cyclic manner, according to a pre-established schedule, and
b) in a cyclic or acyclic asynchronous manner, as requested each cycle by each of those
data-link entities.
Thus this protocol can be characterized as one which provides cyclic and acyclic access
asynchronously but with a synchronous restart of each cycle.dition 3.0 2014-08 INTERNATIONAL STANDARD NORME INTERNATIONALE Industrial communication networks – Fieldbus specifications – Part 4-14: Data-link layer protocol specification – Type 14 elements Réseaux de communication industriels – Spécifications des bus de terrain – Partie 4-14: Spécification du protocole de la couche liaison de données – Eléments de type 14 IEC 61158-4-14:2014-08(en-fr) THIS PUBLICATION IS COPYRIGHT PROTECTED