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Safety protocol runs on any type of industrial Ethernet

20 April, 2010

The Ethernet Powerlink Standardisation Group (EPSG) claims to have developed the first open communications protocol for safety-related data that can run on any version of industrial Ethernet. It says that the bus-independent openSafety system satisfies the automation industry’s demand for a uniform standard for safety systems, and will cut the cost of developing safety-related technologies. For the first time, it offers industrial Ethernet users, a complete, certified safety system, says the EPSG.

At the recent Hannover Fair, the Group demonstrated openSafety systems based on the four most common industrial Ethernet protocols: Sercos III, Modbus TCP, EtherNet/IP and Powerlink. Although other Ethernet user organisations have announced safety-related protocols, the EPSG claims that it is the only organisation offering a working product that runs on all protocols.

The system, which has been certified by TÜV Rhineland, can be used with any fieldbus or industrial Ethernet protocol. It is available as freely downloadable open source software. It offers communication cycles in the microsecond range and will guarantee fast response times and high levels of safety in systems rated up to SIL 4, according to the EPSG.

The Group contends that openSafety will allow manufacturers and plant operators to cut development costs. It will also allow safety-relevant braking distances to be reduced, so that safety margins can be ideally dimensioned and machine cycles can be increased.

Key characteristics of openSAFETY include:
•  data transport that is defined using an flexible telegram format;
•  integrated services for configuring and distributing parameters automatically; and
•  a communication structure that optimises machine productivity using cross-traffic.

It doesn`t matter which protocol is used to transport the safety frames because all of the safety-related mechanisms are integrated into the protocol’s application layer and are thus independent of the underlying transport layer. openSAFETY monitors all transferred data content continuously to ensure that it is complete and in the correct sequence, and that the transfer duration is maintained. Any transfer errors are recorded immediately so that industry-specific communication systems – and even single-channel, non-safe transport networks – can be used as the basis for communications.

The independent Ethernet Powerlink Standardization Group (EPSG) was founded in 2003 to standardise and develop further the Powerlink technology originally introduced in 2001 by B&R. The communication system is an extension of the Ethernet standard, designed to provide real-time data transfer in the microsecond range. The protocol has more than 450 supporters, manufacturers and users, and is used in more than 90,000 machines worldwide.