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Concept for standardized, intrinsically safe Ethernet


Realizing the aim of “Industry 4.0”, also in the process industry, will bring about great technical challenges. Within the scope of PTB’s cooperation with the companies R. Stahl, Siemens and ABB, a project was launched which has clear aims for “Industrial Ethernet”: “Industrial Ethernet” should be easy to use in potentially explosive atmospheres; interoperability between various manufacturers should be possible, and no proof of extensive intrinsic safety should be required.

Although there are already solutions for the use of Ethernet in potentially explosive atmospheres (e.g. remote I/O via optical fibers), an internationally standardized, intrinsically safe version – as in the case of field busses – has so far been lacking. For that reason, a working group – under the auspices of PTB – has set itself the task of specifying intrinsically safe Ethernet, sticking as closely as possible to the usual Ethernet standards of IEEE 802.3. Two different versions of intrinsically safe Ethernet were defined: To connect more complex terminal devices, the version “Ethernet Ex-i” – which supports very high transmission rates of up to 1 GBit/s and has an independent energy supply – is suitable. For simpler field devices, the version “Ethernet Ex-iP” is appropriate. Based on the model of the 2-conductor field busses, the intrinsically safe supply of the field devices is realized via the Ethernet network, together with full-duplex data transmission (100 Mbit/s), so that no separate supply of the field devices is necessary. Besides the conventional intrinsically safe supply, a so-called pseudo-linear source (“F4-i”) is an innovative and promising solution. This enables a connected device to be supplied with a power output of up to 4 W (for Gas Group IIC and Safety Factor 1.5) in an intrinsically safe way.