trying to replicate my DIY can bus device for RaceChrono, like i did with my g80 m3

https://g80.bimmerpost.com/forums/sh....php?t=1959139

basically, RaceChrono Pro allows you to make your own DIY devices and send CAN bus data to it via Bluetooth LE. i am doing this with a Adafruit ESP32 device. used posi-taps to tap into the green/brown twisted pair wires in the passenger footwell. this setup was almost identical to the g80, just different wires, and it worked amazingly on the track, RaceChrono on iPhone 13+ was easily able to handle 25hz GPS via Racebox mini + CAN bus data from 10 channels from 10hz to 50hz (not all PIDs broadcast at the same rate).

i got my hands on the 992 CUP car manual and it had a bunch of PIDs listed, but unfortunately none of those seem to match up. so now i use a raspberry pi + pi can hat to use can-utils and can-sniffer to log data, press pedals and move steering wheel and try and figure out which PIDs are which and decode the data. i wish manufacturers, especially ones that have "track" manuals for their cars would publish these few PIDs that track ppl are usually interested in...

i have tried the latest Track Precision app. its a little buggy, but has a lot of great potential, love that apple allows it on carplay (unlike racechrono), but messing around with it, i still feel like RaceChrono app is crazy stable, can use 25hz GPSes like Racebox mini, and has slightly better analysis interface, so i would really like to get as many PIDs as i can decoded. i see some posts for older generations, like 996, 997, so hopefully some of those PIDs are the same in 992.

EDIT: i didn't realize there was a Data Acquisition and Analysis for Racing and DE sub-forum, maybe an admin can move this there?

 

Finally taking the plunge to wire my Aim Solo 2 DL in to the CAN on my 992.1 T. The green/brown pair is the CAN bus, but which is CAN + and - ?

Also, any tips on how to find the C12 fuse block you mentioned? I see it’s all the way to the right, but not sure how many from the bottom. The embossed fuse image on the back of the panel wasn’t very helpful.

Also, does Aim make an extension for the 7-pin cable?

 

CAN Low: Brown
CAN High: Green

https://www.racelogic.co.uk/_downloa...2)%202019-.pdf

 

i never completed this, it was taking too much time and i eventually just bought a VBOX HD2 setup hah

 

The Aim cable is labeled CAN+ and CAN-, is that high and low?

 

that would be my guess. since these data loggers are read only, if it was wrong, you just wouldn't get any data, and if so, just swap them

 

You might find this fellow’s blog/process helpful in your efforts.

Planet Kris

 

Yes, great info.

Good to see they specify tapping the CAN before the gateway as opposed to after, typical of CAN present at the OBDII port. This is why you always want to do this, if possible.

 

Aren't you afraid of damaging the CAN wires on a porsche? I used to tap canbus on my BMW for JB4 tune, but on a porsche I don't dare to.

 

Am I concerned? Yes. Should I be? I don't know. Using a posi-tap this seems to be a very safe operation and it's reversible. I've never heard of an issue with using posi-taps on the CAN bus, perhaps someone else has and will chime in.

 

Use the proper connectors, like poor-sha suggests, and no issues. At least I haven't had any in more thant twelve hundred installations in sixteen years.

 

yea the canbus wires are thin AF, but just being a little careful and precise with posi-taps and its super easy and i've never had an issue with the 5 vehicles of different brands i've tapped before shrug

 

This is becoming rather frustrating. I bought one of those passive CAN taps only to find out it that I can’t get the wires untwisted enough to fit it.

I went ahead and used posi-taps on the CAN lines in the VBOX doc and connected the Aim cable - nothing. I tried reversing the CAN wires - still nothing. If I plug the Aim OBD 2 cable in it works.

I’m afraid to mess with the posi-taps now that they’re on, but it seemed pretty idiot proof.

I welcome any suggestions, but my next step is to order a bare cable for my CAN sniffer to see if it records anything.

 

did you twist the wires after the posi-taps? CAN wires need to be twisted pair, as they can suffer from interference. i have never used AIM, so i don't know if there is a special setting for turning on CAN vs OBD2, but i have used this method for g80 m3, 992.1 gt3, 992.1 gt3rs, with custom ESP32 + Racechrono Pro, Raspberry Pi + CAN Hat for debugging CAN signals, and with the VBOX HD2 and all 3 instances, things worked immediately.

the porsche CAN bus is 500 kbit/s bus. CAN buses can operate at different bandwidths, etc. is there a setting in AIM to set that? With ESP32, Raspberry Pi, VBOX, they all have ways to set this.


g80 twisted pair taps


992.1 gt3 taps
green / high / +
brown / low / -