Functional Safety Systems in manufacturing plants are an essential part of automation. They are needed for the protection of equipment, lives and the environment. Functional safety systems used to be implemented separately because it was felt that this gave the best security. Modern thinking accepts that a fieldbus such as PROFIBUS is secure and fully capable of carrying safety signals as well as control data. In this section you'll learn a little more about PI's unique PROFIsafe solution and the benefits that it brings to manufacturing. PROFIsafe is one of PI's most important profiles for PROFIBUS and PROFINET. It has led the trend towards ‘networked safety’ and has been rigorously assessed by the world’s safety authorities and declared fully capable of performing the functional safety task. It does this using a ‘black channel’ that co-exists alongside general control signals. Except in an emergency the PROFIsafe signals are invisible. When failsafe devices such as emergency stop buttons or sensors indicate a fault condition, the PROFIsafe network activates a plant shut-down procedure over the fieldbus. Functional Safety used to be considered an expense but now it is considered an investment that can enhance the management of plant and assets.