Reading datas from obd elm327 python-OBD

Question

I would like to log datas via OBD2 with ELM327, and I am new in Python.

I can send a command and get a response. But I cannot send more queries and get the responses, only for the first command, the rest of responses are "None".

My code:

import obd, time


connection = obd.OBD(baudrate=38400, fast=True) # auto-connects to USB or RF port


while True:
    for i in commands_list:
        cmd1 = obd.commands.RPM       # select an OBD command (sensor)
        response1 = connection.query(cmd1) # send the command, and parse the response
        print(response1.value) # returns unit-bearing values thanks to Pint
        # connection.close()

        cmd2 = obd.commands.COOLANT_TEMP # select an OBD command (sensor)
        response2 = connection.query(cmd2) # send the command, and parse the response
        print(response2.value)
        # connection.close()
        time.sleep(0.5)

The output is: (with stopped engine, on ignition)

0.0 revolutions_per_minute
None
0.0 revolutions_per_minute
None
0.0 revolutions_per_minute
None

The expected output:

0.0 revolutions_per_minute
91 degC
0.0 revolutions_per_minute
91 degC
0.0 revolutions_per_minute
91 degC

It is work with closing connection after getting each responses, but it is really slow... I woule like to get responses after max. 1 sec. The optimal would be at least 0.5 s.

Has anyone idea or experience with this? Thanks in advance.

score 1 · Accepted Answer · answered Mar 22 '17 at 17:19

The solution was to set fast mode to false:

connection = obd.OBD(baudrate=38400, fast=False)

Function description:

fast: Allows commands to be optimized before being sent to the car. Python-OBD currently makes two such optimizations:

Sends carriage returns to repeat the previous command. Appends a response limit to the end of the command, telling the adapter to return after it receives N responses (rather than waiting and eventually timing out). This feature can be enabled and disabled for individual commands. Disabling fast mode will guarantee that python-OBD outputs the unaltered command for every request.

Source: LINK

Reading datas from obd elm327 python-OBD

1 Answers1