At the HMI 2010 event EPSG is presenting what it claims to be the first uniform standard for all Industrial Ethernet protocols. According to EPSG, openSAFETY can operate over Modbus TCP, Sercos III, Ethernet/IP and, of course, Ethernet Powerlink (EPL), as well as any other fieldbus systems.
With openSAFETY, the EPSG (Ethernet Powerlink Standardization Group) says it has laid the foundation for the first completely open safety-related data communication protocol for all areas of automation. With communication cycles in the microsecond range, the protocol guarantees fast response times and high levels of safety. The openSAFETY protocol specification and protocol stack have been certified for use in SIL3 systems by the German testing authorities TUV Sud and TUV Rheinland. Due to the safety protocol's low residual error probability, users can implement openSAFETY-based projects requiring SIL4 with suitable additional measures.
Because openSAFETY is bus-independent, it is claimed that it can be used with all fieldbus systems or Industrial Ethernet systems. In order to demonstrate the interoperability of the safety system with different protocols, the EPSG is demonstrating four different openSAFETY systems running on Sercos III, Modbus TCP, Ethernet/IP and Powerlink. The EPSG says that users of Industrial Ethernet systems other than Powerlink now have, for the fist time, a complete, certified safety system available to them. Although other user organisations have been announcing the development of safety-related protocols for a long time, the EPSG says that it is the only one to offer an operational product that runs on all protocols.
The 'black channel' principle of openSAFETY is the basis for interoperability with arbitrary transport protocols. For the functionality of the safety protocol, it does not matter which communications protocol is used to transport the safety frames because all safety-related mechanisms are integrated exclusively on the application layer of the protocol and its functionality is thereby independent of the underlying transport layer. openSAFETY continually monitors all transferred data content to ensure that it is complete, that it has the correct transfer sequence and that the transfer duration is maintained. All transfer errors are recorded immediately so that industry-specific communication networks and even single-channel, non-safe transport networks can be used as the basis for communication.
openSAFETY is said to be characterised by three things: the definition of data transport using an extremely flexible message format, integrated services for configuration and automatic parameter distribution and, in particular, a communication structure that achieves optimum machine productivity using cross traffic. The crucial advantage is the reduction of safety-relevant braking distances, which allows the safety margins to be ideally dimensioned and the machine productivity to be increased.
The EPSG actively supports the use of openSAFETY with arbitrary transport protocols and offers assistance, for example, with certification and conformance tests. The openness of openSAFETY is valid in both technical and legal aspects; the protocol is available for free download as open-source software. The BSD license and the possibility for bus-independent application guarantee that everyone using the technology enjoys high security in their investment, and it enables manufacturers and plant operators to reduce development times.
Follow the link for more information about openSAFETY.