CAN diagnostics

Question

I have to develop a smartphone application which will communicate with a car diagnostic tool. Generally, the protocols used in the diagnostic are KWP2000, UDS and OBD. My question is " how to communicate with the car ? and how to work with these protocols?

Answer 1

You can also refer to UDS: http://neweagle.net/support/wiki/index.php?title=Unified_Diagnostic_Services

If your car has a CAN bus then you will probably need:

1. use a CAN device to be connected to the CAN bus (configured respectively)
2. implement (take from anywhere) the TP CAN messages support
3. write your implementation using UDS protocol over TP CAN messages.

Regards,

Dmitry

Answer 2

Most cars come with an "On Board Diagnostic Port". You can communicate with car's internal using this port. Car's engine will throw data on this port in any of Diagnostic Protocols which includes KWP2000,ISO15765 etc.

You should design something that can communicate from your phone to this port. It can be bluetooth enabled device, connected at this port which will recieve data and transmit to your phone over bluetooth. For example, this

from this onwards,You can process the data in your phone for whatever reasons you want.

Answer 3

Cars since 2001 have the OBD-II port in Europe. US since 1996 I think.

There are various types of OBD-II connectors around. The ELM327-chip inside makes it easy to communicate with the car, since the chip makes the communication ASCII-based for us. All you have to do is send the right commands, and you will get a response in ASCII.

If the application should be ran on a smartphone, I have a few warnings for you. Most connectors have bluetooth implemented, and Android will support that, but WP7, Win8RT and iPhones don support the bluetooth serial port communication you will have to set up. There are also wifi ad-hoc based connectors and it might be possible with them.

http://en.wikipedia.org/wiki/OBD-II_PIDs
On wikipedia there is a list of commands you can send to retrieve real-time data.