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brendan-w / python-OBD

OBD-II serial module for reading engine data
GNU General Public License v2.0
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Changing ELM Protocol Detect Command #27

Closed taylor224 closed 8 years ago

taylor224 commented 9 years ago

Hello,

I used this library to develop ECU Data Logger.

I am using ELM327 v2.1 Bluetooth Module and my car is Honda CR-V 2008.

First I am try to connect ECU with this library, It is failed likes this issue(https://github.com/brendanwhitfield/python-OBD/issues/22).

To find reason to fail connect, I turned on debug console in python-OBD.

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The error occurred at 'ATSPA8' command. After this command, '0100' failed cause of 'ATSPA8' command. The failed message at 'ATSPA8' means, Protocol handshake failed. I searched about 'ATSPA8', but I can't find document about this command. So I changed this command to 'ATSP0'. 'ATSP0' means automatic Protocol handshake. It works with my ECU. If 'ATSP0' works in other ECU, It is better to change 'ATSPA8' to 'ATSP0' in [https://github.com/brendanwhitfield/python-OBD/blob/master/obd/elm327.py].

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brendan-w commented 9 years ago

It actually used to be an ATSP0 command, but some OBD software emulators don't support that command correctly. In fact, I recently learned that even some cars/adapter combinations have trouble with it. I've been peeking at some other OBD implementations, and some have found that manually testing protocols with TP is more reliable. That's hopefully going to be implemented in 0.5.0.

brendan-w commented 8 years ago

Auto protocol has been changed back to ATSP0, and detection is being done with ATDPN (with ATTP as a fallback). Works with software obdsim, and other vehicles. Slated for 0.5.0