§2.8 – Safety

Safety systems protect equipment, people, and the environment. Traditionally, they rely on separately wired circuits that are expensive to build, commission, and maintain. Nowadays functional safety can be done over the bus shifting from safety in hard relays to safety in logic. Adding functional safety to an existing automation network means less engineering effort, reduced cabling, faster commissioning and easier maintenance. Networked safety systems also offer greater flexibility, safety strategies can be easily zoned, partitioned, and changed. Innovative safety architectures become possible with new generations of safety devices such as laser scanners.


PROFIsafe is an additional software layer that provides functional safety over the bus on top of existing PROFIBUS and PROFINET protocols. PROFIsafe ensures the integrity of failsafe signals transmitted between safety devices and a safety controller meeting the relevant safety standards. It works independently of any automation functions even though it is running on the same network. It can be used with either PROFINET or PROFIBUS, in combination if required, in factory and process automation applications.

PROFIsafe has been available since 2001 and nearly 9 million PROFIsafe devices are operational. PROFIsafe is approved for wireless transmission channels such as WLAN and Bluetooth. It can even be used on open Industrial Ethernet backbones.

Please note: Safety is a sensitive area of automation. The dissemination, implementation, and deployment of PROFIsafe technology must be treated seriously. All companies and institutions involved with PROFIsafe conduct themselves according to the PROFIsafe Policy.

Flexible safety architecture

More about how PROFIsafe works

  • PROFIsafe meets the highest safety categories: up to SIL3 according to IEC 61508 / IEC 62061, or Category 4 according to EN 954-1, or PL “e” according to ISO 13849-1.
  • The PROFIsafe profile reduces error probabilities in the data being transmitted between F-devices and F-controllers to the level required by, or better than, relevant safety standards. A series of safety checks are carried out by the PROFIsafe protocol to ensure this.
  • PROFIsafe does not have any impact on standard bus protocols and the automation system connected to the same network operates as normal without interference.
  • All F-devices and F-controllers are tested for conformance to the PROFIsafe protocol by PI Test Laboratories and certified by PI for use in the field.
  • Safety and standard data on the same cable. Also, safety and standard modules can be mixed in one station

Learn more with the PROFIsafe System Description:

System Description: PROFIsafe Technology and Application