Nemecsek

Hi.
I just wrote another post, sorry the double but there are some changes as I found interesting docs. I will now try to delete the old post.

I am trying to read the PT can bus (500kbps, wires red and blue/red) of a BMW 530xi (E61).
I use an Arduino, a can-shield interface and a "crocodile" to read the can signals without cutting the wires. I can already read well the K-can bus (100kbps, wires yellow and black) with this system , so I am sure everything is working perfectly.

Under the hood I found a bunch of wires. According to docs colors must be RED and BLUE/RED. I checked a RED-BLUE/RED twisted pair and I can see only a pulse (every 750ms, the pulse is 0,5 ms long).
Now I just read that there is an extra wire (KL_15) to wake up, and the 3 wires all all together into a "ribbon" cable. That means I am looking at the wrong wires...

Can somebody tell me HOW are they made?
I need an easy place where to place the "crocodile" and read the PT can bus.

Thanx

NoQuarter

Those are pretty easy to find in the wire harness under/behind the glove box. There is a junction box where many of the computer module plug interfaces are.

Nemecsek

Found, NoQuarter. Thank you!
It is BELOW the fuses, not BEHIND.
From the image of connector X13581 I found in BMW Online Wiring Diagram System (WDS) by BMW-Planet.net I wrongly assumed I needed to remove the fuses harness. From another doc I understood I need to remove the glove box instead: it is covering the connectors.

NoQuarter

So.... Whatcha making? If it requires PT-Can it must be something interesting!

Nemecsek

Just reading EVERYTHING I can from the car. I am a programmer and found some info about K-CAN, but that's too... boring. I will leave it there for when I am older
I already did it learning from the scratch on a VW Caddy and it was even too easy to extract something nice. I am using Arduino with canbus shield, a crocodile to read the cables, some Python code to read and save the data sequence. I also bought a chinese bluetooth interface and I am learning how to write android code to play with it.

I would like to read out realtime data about RPM, ABS, torque, pedals, and so on and I assume they are in the PT-can.

Just because they are there, so why not?
I believe it has to do with mountaineering: "I climbed the Everest because it was there"

richie281vn

Hi

Since you worked with Can wires, do you know how to best tap into a CAN wire? I am retrofitting PDC to mine and i cant find any connector with spare pins. Thebonly way seems to be tapping into exisiting Can wires. I read somewhere that soldering and heat tube are not recommended.

Nemecsek

Richie, I am using a can "crocodile": CANbus readers | Wagencontrol: fuel monitoring for GPS tracking systems
It works perfectly and is very sensitive. The only problem is the size of the sensor: being normally can bus twisted pair, you need to "untwist" at least 4 cm. In a car, where cables are short and usually packed together, it can be a little difficult. But it works.
I already used can bus in other applications. It would be possible to add a couple of wires to a connector to read easily a can bus signal on an Arduino Can Shield, but there is a problem with line resistance. It is possible that adding a device the R changes and some smart device signals it as an error...

NoQuarter

I'm not so sure guys. The whole point of a canbus network is to add devices to the network. Certainly there is a length and device limit but nothing to be concerned about here I think.

Just be careful keeping twisted pairs twisted and make good quality connections.

My canbus project not only just listened to the traffic but also communicated back. I used the steering wheel buttons to run a "preferences" routine that put everything where I wanted it for "sport mode" for example.

richie281vn

So would it be ok if I just solder a new twisted pair of canbus wires to add in my PDC? I plan to connect it to the passenger seat's one.










@NoQuarter

Nemecsek

I can only refer about something I read around: the CAN bus of course allows adding other devices, but it looks like there is a "quality control" of the line to detect potential failures inside the BMW can bus. This would recognize if extra devices (damaging the communication line) have been added to the standard ones.
More legend than science.

On the other side I want only read, not write on the bus. I would not like to send the wrong command and explode the airbags during my game...