Ethernet
The public is currently experiencing a great deal about software issues such as e.g. autonomous driving or the gesture control. Behind this, however, it becomes difficut more and more to provide just in time the
necessary information within the car wiring system. Ethernet would be available at 10, 100, or even 1,000 Mbps and therefore a solution of the problem. Compared to CAN with in practice a maximum of 0.5 Mbps a
delightful alternative.
Ethernet has a much longer development than for example CAN. In 2008 it was also tried out in a BMW 7 and here came the challenges. Ethernet is used together with the Internet
Protocol and the Local Area Network, e.g. for long transmission distances.
It can work with more than 100 meter distances and, depending on the development stage, up to four repeaters (hubs), which amplify and then forward the signal. All this a vehicle does not need. However, the
speed of Ethernet is based on the most direct forwarding of data via various switches to the receiver, for which there is basically a worldwide unique so-called MAC-address.
Although Ethernet is also available for optical fibers, in the picture above you can see a typical Ethernet cable. For the LAN connection to the router, in contrast to CAN, there are 4 twisted data lines, however working
in serial mode. Not shielded Ethernet cables were difficult to use in the tests of 2008 because they were too close to potential sources of interference in the vehicle.
In the meantime, however, Ethernet is still going on in cars for some time, but only to the audio or video area as competition for MOST. During the transition from CAN to
FlexRay's guaranteed processing time for more processes was the aim. Opposite to this is Ethernet. If two participants start sending at the same time, they notice this and make them both different
long breaks.
Also the switch distribution only works up to medium load. If the data can not be distributed in time, either the switch is blocked or even data is lost, unthinkable
for engine or safety-relevant applications in the car. You see, in the transmission rates, too, there is announcement and reality. 12/16
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