Multicycle operations in a field bus: application layer implications

The field bus is considered from the application layer point of view on the basis of practical experience involving the connection of a machine-tool to its controller. The user needs are detailed, showing that multiple polling cycles are required. A novel algorithm to ensure multicycle operations which proves to have a very low computational complexity is described. It is compared with a conventional scheduling algorithm. The possible influence of multicycles on the application layer services is discussed, and a set of primitives that are sufficient, efficient, and easy to use for a nonnetwork specialist are detailed.<>