4 ms·
> using ethernet and PoE means you don’t have to run one off wires to each device, they can share a bus which results in half the copper being used in a lower v
by KaiserPro 3y ago
> using ethernet and PoE means you don’t have to run one off wires to each device, they can share a bus which results in half the copper being used in a lower voltage car
Ethernet isn't a bus, its point to point. PoE over cat5/6 uses 4 pairs of UTP.
so it might be used to join aggregate things together, but it won't be a bus.
Yes, you can increase the datarate, but ethernet is fundamentally unreliable. So you'll need to either strictly manage the bandwidth requirements of attached devices, or put in flow control(expensive) or use the weird "reliable" Ethernet they made for fibre channel replacment ($lol and you need to pay to make it automotive rated)
48v is logical, and a lot of other people are doing it.
PoE is probably stupid
Ethernet makes kinda sense, but firewire would probably be better, its a bus and rated for life critical use.
- TheLoafOfBread 3y agoEthernet can be used as a bus (see CSMA/CD), but if there are more than 2 nodes, performance of whole bus will go to complete shit and there is no guarantee that an ECU will transmit a single packet during its run, because that CD has no automatic arbitration, it is just random disconnection and try again. Not good for critical things like ABS. That's also whole reason why FlexRay was spawned, because even that FR is inflexible abomination of a protocol it actually guarantees that every ECU on the network will get a time window to transmit its own data.
- KaiserPro 3y ago> CSMA/CD Lol I'd forgotten about base-T.
- andrewf 3y agoI think that's what 10BASE-T1S (standardized in 2019) is for. It has a non-CSMA/CD arbitration scheme. https://www.electronicspecifier.com/industries/industrial/an-introduction-to-10base-t1s https://www.electronicspecifier.com/industries/industrial/an...
- TheLoafOfBread 3y agoSo... you need new PHYs and new Ethernet controllers to use T1S?
- andrewf 3y agoA lot of the Googleable information seems to be from chip vendors who want to sell those things :) Yeah it's intended for new designs. Fewer wires than the original 10mbps ethernet.