Zebra Open Safety

History of efforts and costs

Rising development costs for communication systems

A brief review of the history of bus-based automation may serve to illustrate how investment risk has been increasing in line with growing complexity. Ten years after the introduction of the first fieldbus, the market was full of different, competing systems. Infighting over the standardization of the technology ensued. Until the present day, industry experts know this phase as the “fieldbus war,“ which only seemed to end  with the introduction of the IEC61158 – a weak compromise because still, even this conclusion do not bring any overall system compatibility. Still, even this conclusion did not bring about overall system compatibility. It should be noted, though, that development costs for first generation buses were comparatively low, whereas their market potential was sizable. The entry of Ethernet technology into industrial data communications marked the next stage of development, one that was widely associated with the expectation that, finally, a universal standard would prevail. However, as different manufacturers chose strongly divergent approaches to enable real-time performance with this technology, what followed was the fieldbus war all over again. Amongst a multitude of systems, about half a dozen have been able to claim major portions of the market: Profinet, Modbus-TCP, EtherNet/IP, which all provide soft real-time performance, and the hard real-time systems POWERLINK, EtherCAT, and SERCOS III. There was a moderate increase of development costs for Industrial Ethernet solutions in comparison to conventional fieldbuses. At the same time, the sales potential could not be increased in the same proportion.

Safety technology – a special case

Things look markedly different, however, for the development and certification effort required to make products designed for use in safety-sensitive areas, whenever these are to comply with the IEC 61508 standard covering the “functional safety of electrical, electronic, and programmable electronic safety-related systems.” In this area, there is a ten-fold increase of development costs over those for non-safe fieldbus technology. Moreover, manufacturers must demonstrate a wide range of experience relating to the interpretation of the standards, and must have specialist know-how in certain methods and procedures. With highly demanding requirements and high costs on the one hand, and, at the current time, a comparably small market for such products on the other, a “battle of the systems” would seriously impede the further development of bus-based safety technology. E.g. sensor makers would face immense efforts and high risk exposure if they were to develop their products in keeping with the safety standards of various different safety protocols.

The solution: openSAFETY

A tried and tested, non-proprietary system, openSAFETY resolves this situation in a way that benefits both manufacturers and users. Thanks to the Black Channel principle that makes the safety protocol suitable for use with all fieldbus and Industrial Ethernet technologies, safety technology manufacturers can focus on one universal system, and must only complete one safety development process to serve all standard fieldbuses. Both the effort involved and the investment risk are drastically reduced. openSAFETY benefits plant and machine operators in much the same way. While they are responsible for safety in their machinery, they usually have no say regarding the communication systems used in it. These are predetermined by the control systems the machine manufacturers have chosen to use. However, openSAFETY gives machinery operators a consistent safety solution for a heterogeneous control network in its entirety.