Bluetooth connect to ELM327

Question

I deal with a thesis on the topic "car diagnostics via bluetooth". However, now I'm stuck in the problem. I have application, which can connect bluetooth to mobile (from tablet - android to android). Its ok state is CONNECT. But when I tried to connect to the OBD adapter. It was unsuccessful.

Trying to connect approximately this way:

public void run() {
    // Cancel discovery because it will slow down the connection
    mBluetoothAdapter.cancelDiscovery();

    try {
        mmSocket.connect();
    } catch (IOException connectException) {
        connectException = connectException;
        mHandler.obtainMessage(NOT_CONNECT).sendToTarget();

        try {
            mmSocket.close();
        } catch (IOException closeException) { }
            return;
        }

        mHandler.obtainMessage(SUCCESS_CONNECT, mmSocket).sendToTarget();
    }
}

Please can you advise me also how to create a valid AT command, which is then queries the OBD adapter?

Thank you for helps!