Two devices and obd2 WiFi

Connectivity General Discussion
1

Hi all,

New to the forums but looks like I’ll stick around. :slight_smile:

I’m intending to use two android tablets in a 2004 bmw e60. Planning to connect them both using a obd2 Wi-Fi adapter and show speedo on one and engine info on the other. (Either via multicast or just direct app connection if possible)

Does this sound like a sensible way to do this? Any previous experience anyone can share? Or maybe I need to go wired for reliability?

Any and all advice or suggestions gratefully received.

Cheers,
Milan

2

You would need two separate OBD2 adapters for two tablets.

I’d recommend that:

  • Tablet 1 is connected to your vehicle, either with OBD2- or preferably with CAN.

  • Tablet 1 has mobile internet and hotspot active.

  • Tablet 1 shares values with data multicasting.

  • Tablet 2 connects to Tablet 1 hotspot

  • Tablet 2 receives data via data multicasting.

3

Thanks for the reply.

Would I be able to accomplish what you are suggesting using the OBDLINK MX+ Bluetooth adapter? Wifi would still be free for a hotspot to the other tablet. Or would bandwidth be an issue with two devices?

Thanks,
Milan

4

OBDLink Bluetooth adapter will work in this scenario. Bandwidth will be ok, as comms is very slow over OBD2 anyways.

5

Thanks again. Just one more question.

I am intending to use these as the primary (only) dash on a racing car - you say comms is slow - is it so slow as to be unreliable in terms of the time it takes to update reading and sensor info? Or perhaps for robustness and speed I should go wired? (And if so can you please recommend a CAN adapter to android tablet that you have found too be consistenty robust and reliable regardless of cost?)

Thanks in advance.

6

OBD2 is slow by protocol design, not by transport. OBD2 is request-receive type of protocol, so (typically) each value is asked one by one. This alone causes delay as each value is requested so there is two way communication for every request. Additionally, as OBD2 is a DIAGNOSTIC protocol, on most vehicles its not designed for speed- hence getting the reply from the vehicle takes additional time.

The speed that you get the data over OBD2 depends heavily on vehicle. Some are ok(ish), most are slow. For racing, I would assume that you will not be happy with the data rate over OBD2 connection. As what is fast enough is also very subjective.

As for CAN connection with tablet, try Bluetooth version of MeatPi adapter. USB adapters work very well but will prevent charging on tablets with only one USB port. It seems that we do have CAN XML for BMW E90 335i. That may work on your vehicle too.

7

Thanks for all that info - I have it all running as you suggested using the MeatPi adapter bluetooth. It seems to read fine on the diagnostic screen but won’t be able to fully test it until I put the ECU back in the car. It’s on a bench at the moment. And I used the BMW E93 description file I found in the app - I assume that’s the one you meant.

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