PROFIsafe (PROFIBUS safety or PROFINET safety) is the first open functional safety communication technology for distributed automation systems worldwide. Its specification for PROFIBUS DP and PROFIBUS PA was published first back in spring 1999. It incorporates the knowledge of more than 25 renowned safety companies. Extensions for the Ethernet based PROFINET IO followed in fall 2005. More than 30,000 automation systems with more than 300,000 PROFIsafe nodes are currently in use worldwide (spring 2007).
In the past, safety automation had to be "hard-wired" and based on "relay" technolgy due to existing international standards. This changed with the advent of a new standard – IEC 61508 – specifiying how microcontrollers and software can be used in safety automation. This triggered the development of PROFIsafe, which was to integrate safety into the existing standard PROFIBUS fieldbus technologies.
PROFIBUS, the world market leader in fieldbus systems, and standardized in IEC 61158 and IEC 61784-1, became an enabling technology through the introduction of PROFIsafe. Totally new concepts for integrated standard and safety programmable controllers as well as integrated remote I/O could be realized. New integrated safety for drives such as "safe operating stop" which avoids undefined stop positions after tripping through an emergency stop no longer were remaining a dream. Additional monitoring functions such as "Safely limited speed" or "Safely limited torque" will cause revolutionary applications to occur in the near future.
PROFIsafe is
PROFIsafe is designed as a separate layer on top of the fieldbus application layer and reduces the error probability of the data transmission to the level required by or better than the relevant standards. PROFIsafe messages are using the existing standard fieldbus cables in coexistence with the standard messages ("Single Channel"). PROFIsafe does not benefit from any error detection mechanisms of underlying transmission channels and thus supports the securing of whole communication paths, even backplanes inside controllers or remote I/O. PROFIsafe coined the term "Black Channel" for this concept, which now is adopted by most of the other safety fieldbusses. PROFIsafe can be used in safety applications up to Safety Integrity Level 3 (SIL) according to IEC 61508, Performance Level "e" (PL) according to ISO 13849-1, or Category 4 according to EN 954-1.
PROFIsafe is using expanded fault (errors and failures) detection mechanisms such as
PROFIsafe safety measures usually are realized in software and simply added as a safety layer on top of the PROFINET application layer 7 (ISO/OSI model) without changes to the other layers. The safety layer is responsible for the transmission of safety related process data in coexistence with non-safety related data such as diagnosis information. Therefore, safety devices are able to benefit from existing PROFINET services, thus reducing the overall system and engineering costs.
PROFIsafe is standardized in IEC 61784-3-3. It also is a Chinese standard (GB/Z 20830-2007).
Different industry requirements are taken into account. Factory automation deals with short signals processed at very high speed, while process automation involves longer process values that may take a little more time. PROFIsafe therefore offers two different process data lengths limited to a maximum of 12 bytes and 122 bytes respectively.
PROFIsafe runs its own web portal on www.profisafe.net with many more details on the technology and hints for device developers, integrators and end users.
The Technology of PROFIsafe is driven by the PROFIBUS and PROFINET Working Group TC3/WG5, the PROFIsafe marketing is managed by PROFIBUS and PROFINET Working Group TC5/WG6.
