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-   -   VBox CAN data model for Porsche 991.1 (https://rennlist.com/forums/data-acquisition-and-analysis-for-racing-and-de/1133485-vbox-can-data-model-for-porsche-991-1-a.html)

Jabs1542 03-13-2019 10:10 AM

VBox CAN data model for Porsche 991.1
 
Iíve recently installed a VBox HD2 into a 2013 Porsche 991.1 and am having trouble with Brake Pressure. The only CAN model that gives me any brake data is the Ď991.2 2015 -Ď model, but here the brake pressure data looks almost like integers (in bars) with no decimal data (basically square wave brake application, which doesnít reflect the brake application at the time). :banghead:

Question: Does anyone driving a 991.1 with VBox have a properly working Brake Pressure data channel? If so, what CAN Model are you using? Which wires in the massive loom did you tap into when doing the physical connection (I have learned there are multiple CAN buses running through the car)?

Any experiences would be helpful - TIA. :bowdown:

ProCoach 03-13-2019 11:00 AM

You have an email.

I have successfully gotten brake pressure, throttle and steering, as well as engine speed, from a 2012 non GT3 991.1 Carrera S. I thought the drivetrain CAN (yellow/red, yellow/brown) was the connection and the 911 (991) PIDís were what was loaded, but I think youíve tried that. We just recently sussed the newer 991.2 cars by using a different bus (orange/purple, orange/brown) and that cured the issue on some earlier cars. Porsche generally did not alter PIDs between year models or even series of cars (as many of the 981 are the same).

Will ping you offline and help you get this straight.

lisocayman 05-12-2019 01:25 PM

Iím trying to figure out the custom PID to pull brake pressure from the ODBii port for a 991.2 GT3. Do you know the code?

ProCoach 05-12-2019 06:26 PM

No, but you can see if anyone in the AutoSport Labs has sniffed the CAN at pins 6 and 14. While AiM has worked out a reasonable protocol from the OBDII, Racelogic has focused on the direct connection protocol.

For that reason, I don't connect HD2's to the OBDII on those cars. Use the yellow/purple-yellow/brown pair and brake position from the drop down menu in VBOX Setup.

As a matter of fact, there's a new connection mode coming that will get a whole lot more than what's been logged so far, specifically from the latest Porsche models...

ShakeNBake 05-12-2019 07:50 PM

There are three different codes from various 991 code sets, try putting them all in a scene and seeing what you get. I've noticed on a few cars I've done that you can get brake pressure, but you have to add an offset and scale it to get a % reading.

ProCoach 05-12-2019 08:19 PM


Originally Posted by ShakeNBake (Post 15836182)
There are three different codes from various 991 code sets, try putting them all in a scene and seeing what you get. I've noticed on a few cars I've done that you can get brake pressure, but you have to add an offset and scale it to get a % reading.

Yes, but this fellow is asking for codes from the OBDII port CAN, not the CAN that the codes were sampled and developed for the dropdown menu...

He needs to go directly to the car, not to the OBDII. He could build one, but he'll need to sniff and build a .dbc specifically for the CAN present at the OBDII.

boxer-11 05-21-2019 07:48 PM

There are five CAN buses in the modern Porsche network architecture: CHASSIS, COMFORT, CRASH, DRIVE, and MMI (aka DISPLAY in some places). Some message IDs are local to the bus that generates them. Others are re-transmitted on a different bus for consumption by systems on the remote bus. This appears to be done via a gateway to which the five buses all connect. If you get to tap into one only, CHASSIS has more of the interesting things we care about than DRIVE does; PSM lives there and wants to know all sorts of things from the other buses so while it's not a perfect super set, it has most everything you want. CRASH you definitely want to stay away from (especially if you're a fumble-fingers like me and end up crashing the bus occasionally! ;)). COMFORT you can ignore (unless you want to log what your seats are up to! ;)). MMI has just a couple of interesting things that aren't on CHASSIS (notably that's where the TPMS controller lives). Unfortunately I don't know the wire color mapping to the bus names, but any shop with the Porsche PIWIS tester/docs can look that up for you. CAN messages via the OBD-II come from the gateway but what is passed through to the OBD-II connector wires is a definite subset of messages that appear on the other buses.

ProCoach 05-21-2019 08:21 PM

Well, you have yellow/red-yellow/brown (AiM 991_911, includes brake pressure, steering angle, throttle position, engine speed, also early VBOX protocols), you have yellow/black-yellow/brown (Euro 991.1 GT3 VBOX) and yellow/purple-yellow/brown (late 991.1 and all 991.2 GT2RS/GT3RS VBOX), and there is now a connector with all chassis and drive present.

Problem is that the PIDs are all different for the different buses, so a unit set up with a .dbc that works with one doesnít work with another. You can pick and choose, building your own, but that takes time.

92-95% of the cars work now, but there are still a few outliers (2012 base car, 2013-2014 base cars and 2014 GT3) that are still tough to build scenes for. At least all the .dbcís are known now to do that.

Matt Romanowski 05-21-2019 09:35 PM


Originally Posted by boxer-11 (Post 15856654)
There are five CAN buses in the modern Porsche network architecture: CHASSIS, COMFORT, CRASH, DRIVE, and MMI (aka DISPLAY in some places). Some message IDs are local to the bus that generates them. Others are re-transmitted on a different bus for consumption by systems on the remote bus. This appears to be done via a gateway to which the five buses all connect. If you get to tap into one only, CHASSIS has more of the interesting things we care about than DRIVE does; PSM lives there and wants to know all sorts of things from the other buses so while it's not a perfect super set, it has most everything you want. CRASH you definitely want to stay away from (especially if you're a fumble-fingers like me and end up crashing the bus occasionally! ;)). COMFORT you can ignore (unless you want to log what your seats are up to! ;)). MMI has just a couple of interesting things that aren't on CHASSIS (notably that's where the TPMS controller lives). Unfortunately I don't know the wire color mapping to the bus names, but any shop with the Porsche PIWIS tester/docs can look that up for you. CAN messages via the OBD-II come from the gateway but what is passed through to the OBD-II connector wires is a definite subset of messages that appear on the other buses.

This sounds like a very well informed and experienced explanation. Joe Hullett and Chris Brown have done some interesting things with Porsche CAN, but I don't know which systems they've grabbed. I would assume it's just chassis.

ProCoach 05-21-2019 10:06 PM


Originally Posted by Matt Romanowski (Post 15856838)
Joe Hullett and Chris Brown have done some interesting things with Porsche CAN, but I don't know which systems they've grabbed. I would assume it's just chassis.

It's been mostly for MoTeC and some interoperability on the newer factory race cars. They've done a spectacular job, together and separately.

Way more than chassis, the list for the 981 (similar to 991) is remarkable, eighty-eight chassis/drive/comfort channels alone, plus all the diagnostic channels unique to MoTeC.

They grab from multiple buses, however. The first and third I referenced.

If anyone needs MoTeC templates, they'll be glad to sell them to you, locked to your device. Recommended highly. I have resold a few along with MoTeC hardware sales, from both guys.

Honestly, the VBOX (and the AiM) doesn't have the analysis or display configurability to visualize (or even gain benefit) from a majority of these channels.

Beside, that is not what most people need, IMO. The ten or eleven channels present in the VBOX templates work well with the display and analysis capability of the software and cover a majority of needs for driver improvement.

lisocayman 05-21-2019 10:27 PM

For a 991.2 GT3 would people recommend the aim solo2 DL with a CAN tap? Is this easy enough to install? Iím trying to not spend a lot of $ but HLT analysis just isnít as good as my old traqmate setup.

ProCoach 05-21-2019 10:30 PM

Yes, super easy for both. Posi-Taps, an Add-a-fuse and about thirty minutes should do it.

boxer-11 05-22-2019 01:11 AM


Originally Posted by Matt Romanowski (Post 15856838)
This sounds like a very well informed and experienced explanation.

Sort of. I went and did Chris Brown's MoTeC class and I have a C125 now in which I use templates that I got from him. As Peter points out, those templates are the magic -- and they come locked. However I have added a few bits and pieces of my own for things that I've been able to ferret out of the data stream. It's laborious work though without any docs -- dump the message stream via the C125 to a text file and then sort/filter in excel. I do firmware for a living, although not for cars, so I have some experience and thus intuition on how the Porsche engineers set things up. I did help a little with the work to put the CAN taps into my car which meant I was in the shop and got a peak at some of the docs that talk about the network architecture and wiring (block diagrams that show which control units are on which buses; should have taken more notes!). That's really the sum total of my knowledge (so far :)). Well, except that it took two goes to get the CAN taps right because initially we had DRIVE and COMFORT and it sort of worked because many of the CHASSIS messages are on DRIVE too but I didn't get all the goodness from Chris' templates until we flipped the taps to CHASSIS and MMI...figuring that out sort of solidified my mental model of the architecture. At any rate, I just mention all this in case it helps anyone know what to ask for when placing CAN taps -- there's no doubt you get more and better data from the buses direct compared to OBD-II, provided you hook into the right place.

[OK, well you need the message decode magic in some form also of course...Chris and Joe seem to have the lead by a country mile on that aspect for Porsche...but Peter is right: AIM and RaceLogic have certainly figured out more than enough to be useful for most purposes.]


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