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0 pointscontingencies6y ago0 comments

As I see it there are two properties of a networked system this can possibly enhance: (1) predictability, and (2) a reduction in overall latency. On the former it is only a small part of any goal or guarantee of total predictability. On the latter we should note that it is of significantly decreasing importance as bandwidth increases, which Ethernet enhances greatly, particularly on low node systems with relatively low bandwidth requirements, which covers most industrial deployments. Therefore it's sort of a 'meh' feature outside of specific requirements.

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monocasa6y ago· 2 in thread

Which is why you see it heavily used in distributed real time systems where those guarantees are valuable, even at the expense of raw throughout.

rurban6y ago

And that why you see more and more Gigabit Ethernet replacing stone-aged protocols such CAN, Profibus or Firewire, because a simple Ethernet Chip is dead cheap, >100x faster and comes with a modern memory-mapped driver, the others not. It makes hard real time latency and throughput much easier. With CAN you cannot get very far, and the typical CAN multiplexing tricks get dirty very soon.

monocasa6y ago

You can get CAN to go pretty far.

And real time latency is not "dead simple". A low priority message will always lose out to a higher priority message on CAN. With ethernet a low priority task can flood the bus if the circumstances are right.

Also, which MCUs come with gigabit ethernet?

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