Sorry, I missed your post before mknox:
Why would they mandate how the signal has to traverse the car's systems? I don't really know, but it just seems more likely that regulators would require a specific functionality and not get in to how it's implemented. The example of the OBD-II port was mandated, but from an emission control perspective. That's why the Model S OBD-II port has nothing on it other than 12v power.
First off, "requirement" and "regulators" aren't necessarily related. It is rather more common than you might think that manufacturers agree to a self/joint council standard such as ISO. That's how OBD got started. Regulators stuck their noses in and *used* it for emissions monitoring, but that's not why it existed in the first place. It is as the name suggests: "diagnostics". An attempt at standardizing the computerized diagnostics across makes and models. But then everyone started to cheat lol.
But as for the why they would care about the "how" rather than (or in addition to) the "what"... it has to do with reliability of data and interference, but also costs of independently developing a "best practices" method. We actually see this right now with EV. If Nissan and Tesla got together and co-developed a standard for rapid charging, we'd see a lot more chargers and Leafs and Teslas would be parked side-by-side and they'd both share in development costs. Would hat be a good thing? Well it certainly could be if they both worked to the greater goals and shared equally. Or it could mean you're behind a line of 20 Leafs waiting to charge your MS because Tesla gave and Nissan took. Who knows, but that's not really my point. If we see an issue where Leafs *attempt* to use Tesla chargers, and people start dying (I have no idea if that would remotely be the case, I'm making a fictitious point) then we might see a standard enforced in the future.
This kind of happened in the 90s when Mercedes tried using some strange token ring network protocol they whipped up to transport sensor data. OK, nobody died (as far as I know), but there were huge reliability issues. MB is still recovering from that reliability reputation hit. At the same time BMW adopted CAN BUS that Bosch (I think) pioneered probably a couple decades earlier that proved to be extremely fault tolerant and, more important, reliable in an uncertain environment (and no environment is as uncertain as automotive!). How exactly we got from there to 2007's universal adoption, I don't know... and whether or not it is enforced, I don't know. But you won't find a manufacturer today, I don't think, that sends signals from a sensor (most any sensor) to the ECU, MCU, SAM or other controller without it being over a CAN network. There are other similar standards for specific systems like HVAC and airbags, although they are often also found on the CAN network for convenience.
That's why the Model S OBD-II port has nothing on it other than 12v power.
How do you figure that? There's got to be a lot more going on than 12v power. Tesla would be fully exempt from putting an OBD-II port, but there is one (I saw it today). There's no way they went through that expense to only supply voltage. I mean, I haven't tested it myself... but certainly they're using it as a diagnostics port. I should have brought my equipment with me on my drive
I would have had the time and no prying eyes. I did consider it, but it felt a bit disingenuous as I was there to decide on buying the car, not seeing what data I could pull.
Obviously I have no first hand experience with the car, but I would be absolutely shocked if the sensors weren't on the CAN network and, if true, I'd be equally shocked if the CAN wasn't fed to the OBD-II port. If there is CAN, then I can read it. There's no encryption with CAN. Back up.. .I shouldn't say that. There is. But it isn't worth the performance hit.
Man, now I have to buy it just to see what I can see
