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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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I am getting "query failed, no connection available" #166

Closed Oswaldoo97 closed 4 years ago

Oswaldoo97 commented 4 years ago

(This is a post that I was going to post on the Raspberry forums but I couldn't post it for problems with mi IP. Sorry if it causes discomfort)

Hello everyone, this is my first post on the Raspberry forums and I would really appreciate your help with this issue that I have.

[THE PROJECT]

I am trying to do a Head-Up Display using the ELM327 Bluetooth and the Raspberry PI 3B+

[THE PROCEDURE]

$ bluetoothctl

power on

pairable on

agent on

default-agent

scan on

In this part, I get the ADRESS of my ELM327 A2:2A:19:04:00:00

pair A2:2A:19:04:00:00

trust A2:2A:19:04:00:00

quit

At this point the bluetooth connection is done with no problems.

$ sudo rfcomm bind rfcomm0 A2:2A:19:04:00:00

$ screen /dev/rfcomm0

In this part the screen is openned and I send the following AT commands.

After sending the last 4 commands, I can request for the vehicle parameters like speed, rpm, coolant temperature, etc, with PID commands.

010C (For RPM) 010D (For speed) 0105 (For coolant temprature)

and I get the measure of the parameters but in a hexadecimal code, therefore I have to interpet that hexadecimal code in a decimal code, and for this part, there are a obd library that make the job, the library is called python-obd.

Here start the issue

[THE ISSUE]

In the link of the library there is a simple code that you can use to get the RPM in a decimal value. The code is the following:

import obd

connection = obd.OBD() # auto-connects to USB or RF port

cmd = obd.commands.RPM # select an OBD command (sensor) response = connection.query(cmd) # send the command, and parse the response print(response.value) # returns unit-bearing values thanks to Pint

I try to run that code but I get the following responses

[obd.obd] No OBD-II adapters found [obd.obd] Cannot load commands: No connection to car [obd.obd] Query failed, no connection available None

And this is the issue that I am getting, please help me, I can't find the solution to this problem. I don't know if the problem is the ELM327, the Raspberry, the car or another thing.

Something that I would like to add is that two weeks ago my project was working with no problems, I had an ELM327 that was working fine and I was getting the vehicle parameters when I asked for it, but unfortunately my partner damaged the ELM327 and we had to bought a new one, but it didn't work (I think). :( After that I was analyzing the damaged ELM327 and the new one and I realized that the microcontrollers were different and today I bought another one with the same microcontroller than the damaged one but I am still getting the same issue. :(

Thank you!

alistair23 commented 4 years ago

This line explains it:

[obd.obd] No OBD-II adapters found

You don't have any adapters. Do you see your adapter under /dev/ or in dmesg?

Oswaldoo97 commented 4 years ago

But I have connected my ELM327 in the OBD port, and I am getting the data of RPM, SPEED, COOLANT TEMPERATURE, but in hexadecimal and when I try to use the library to interpret the hexadecimal code to decimal code, I get the issues I posted.

Sorry, can you tell me exactly how can I see my device? Or how can I run the commands you told me? (/dev/ and dmesg), thank you!

alistair23 commented 4 years ago

Ah, I missed that you can connect to /dev/rfcomm0. Can you specify that as the port?

Oswaldoo97 commented 4 years ago

Yes I have sepecified the device in the port 0, and also I did the same with the first ELM327 I bought (with the damaged device which I was using to get the parameters). But with the 2 new ones I am getting this issue, but I don't know why :( Tomorrow I will try with another car, but today I wanted to know if the issue isn't caused by the ELM327.

alistair23 commented 4 years ago

I don't think it's the car, it can't connect to the port. It seems strange that you don't get any more logs, have you turned debugging on?

Oswaldoo97 commented 4 years ago

When I put the following line in my code: obd.logger.setLevel(obd.logging.DEBUG)

I get the following lines:

[obd.obd] ================python-OBD (v0.7.1)=================== [obd.obd] Using scan_serial to select port [obd.obd] Available ports: [] [obd.obd] No OBD-II adapters found [obd.obd] Cannot load commands: No connection to car [obd.obd] ================================================ [obd.obd] Query failed, no connection available None

alistair23 commented 4 years ago

Manually specify the port

Oswaldoo97 commented 4 years ago

Sorry man, can you tell me how can I specify manually the port?

Also I have launched this code to see the available ports and I only get this "[]"

import obd ports = obd.scan_serial()
print ports

alistair23 commented 4 years ago

The documentation explains it: https://python-obd.readthedocs.io/en/latest/Connections/

connection = obd.OBD("/dev/rfcomm0")

Oswaldoo97 commented 4 years ago

Now I get the following response:

[obd.elm327] [Errno 16] could not open port /dev/rfcomm0: [Errno 16] Device or resource busy: '/dev/rfcomm0'

alistair23 commented 4 years ago

You will have to see if something else has opened the port.

Oswaldoo97 commented 4 years ago

I was typed "sudo rfcomm bind rfcomm0 00:00:00:33:33:33", because I tought that I had to write it before putting the port manually, therefore I was getting the device was busy. I have rebooted the Raspberry and I launched the code and now I get the following responses:

[obd.obd] ======================= python-OBD (v0.7.1) ======================= [obd.obd] Explicit port defined [obd.elm327] Initializing ELM327: PORT=/dev/rfcomm0 BAUD=auto PROTOCOL=auto [obd.elm327] [Errno 2] could not open port /dev/rfcomm0: [Errno 2] No such file or directory: '/dev/rfcomm0' [obd.obd] Closing connection [obd.obd] Cannot load commands: No connection to car [obd.obd] =================================================================== [obd.obd] Query failed, no connection available None

alistair23 commented 4 years ago

Now the file doesn't exist, that seems to be worse.

Oswaldoo97 commented 4 years ago

I have tried and tried but unsuccessfully :( Do you think that maybe could be a problem with thethe programation of thethe microcontroller that I could fix with the AT commands?

alistair23 commented 4 years ago

If you can't connect then I don't think so. That seems like a problem on your host side.

Oswaldoo97 commented 4 years ago

What do you mean with "host side"? To keep us in touch, I have bought 3 new ELM327 on Amazon which get to my home on wednesday. I have bought that with the purpose of discarding issues with the scanner. By this time on wednesday I will be posting my result and I hope success im that process.

alistair23 commented 4 years ago

Host side is the machine that is connecting to the OBD connector.

Oswaldoo97 commented 4 years ago

Hello again, the issue has been solved. I was getting issues due to the automatic connection that I was doing between the raspberry and the obd2 port/elm327, because I had configured the raspberry to connect automatically to the scanner once rebooted the raspberry, but to do this procces, I had type this code line "sudo rfcomm bind rfcomm99 (MAC address)" instead of "rfcomm bind rfcomm99 (MAC adress)".

Thank you anyway!

By the way, do you know if I can get the fuel level of the ELM327? Because I have tried with torque and with the raspberry and I can't get that.

ksrm0024 commented 4 years ago

Hi there,

I recognize that this is an old thread, but I am having similar problems. I have:

import obd connection = obd.OBD("/dev/rfcomm99") response = connection.query(obd.commands.RPM) print(response.value) connection.close()

Which returns

[obd.elm327] [Errno 16} could not open port /dev/rfcomm99: [Errno 16] device or resource busy: '/dev/rfcomm99' [obd.obd] Cannot load commands: No connection to car [obd.obd] Query failed, no connection available None

I have tried this with both rfcomm bind rfcomm99 and sudo rfcomm bind rfcomm99 but I cannot seem to get it to work, despite being able to get values from Screen. How exactly did you get it to work?