The PROFIBUS application profile "PROFIsafe - Profile for Saftey Technology"
describes the mechanisms for safe communications between fail-safe
peripherals and fail-safe controllers. It is based on the requirements of
the standards and directives for safety-oriented applications like IEC 61508
and EN954-1 as well as on the experience of the fail-safe device
manufacturers and the PLC manufacturers community. The new version 1.20
supersedes its former draft version 1.0 that was published for review in
1999 and the follow-up version 1.11 from July 2002."