ISO 21919-2:2021

This document deals with the safety interface and control interface. It allocates signals to a conformance class and/or conformance option. It describes the detailed functions of each signal, describes and displays the timing interactions between signals in flow charts and shows examples for safety matrices and safety-related functional relationships.
This document defines three conformance classes and dedicated conformance options. Classes and options consist of a number of signals to:
—    allow a flexible adaptation of the interface(s) to a project-specific scope of functions and simultaneously;
—    tie sets of signals tight enough to avoid unnecessary coordination efforts between suppliers of the machine tending systems and machines.