Safe data-transfer protocol
Just introduced is SERCOS ' safety (SS) concept, a protocol extension compatible with the established transmission mechanisms of the SERCOS interface. SERCOS interface is said to be used within safety applications up to SIL 3 (safety integrity level), according to IEC61508 even with the shortest cycle times. Independent of the type of data—command values, logical signals, safe logic, or process information—the SERCOS interface is said to provide a homogeneous, continuous solution for automation.
SS is claimed to be independent of the transport layer, so that any transmission physics can be used. The extension is available for SERCOS II, SERCOS III, and , other transmission physics, as no special requirements for transmission components need to be fulfilled. Protocol routing capability allows a safety network to be extended over several subordinate SERCOS networks. The safe data container, embedded in the SERCOS III data, may transfer up to 64 bits of safe user data.
SS reportedly is most effective when used in combination with the new Ethernet-based SERCOS III. Safe data can be exchanged between slaves directly using the peer-to-peer, cross-communication capabilities of SERCOS III, without collection and re-distribution of data by a central master safety control.
Combining SS with the fault tolerance provided by the hardware redundancy of SERCOS III reportedly achieves safe, highly dependable automation solutions that can be implemented for centralized and decentralized safety-applications.
TÜV Rheinland is presently investigating SS. TÜV, an international technical service provider, evaluates, tests, and certifies product safety and quality. The specification is expected to be approved by the TÜV in early 2006, and will be available free to all SERCOS members. The first SS productsalso will be available in 2006.