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Serial module for handling live sensor data from a vehicle's OBD-II port

Project description

A python module for handling realtime sensor data from OBD-II vehicle ports

This library is forked from:

Dependencies

  • pySerial
  • OBD-II adapter (ELM327 Bluetooth Adapter or ELM327 USB Cable)

Usage

After installing the library, simply import ‘obd’, and create a new OBD connection object. By default, python-OBD will scan for Bluetooth and USB serial ports (in that order), and will pick the first connection it finds. The port can also be specified manually by passing a connection string to the OBD constructor. You can also use the scanSerial helper retrieve a list of connected ports:

import obd

connection = obd.OBD() # create connection object

# OR

connection = obd.OBD("/dev/ttyUSB0") # create connection with USB 0

# OR

ports = obd.scanSerial() # return list of valid USB or RF ports
print ports
connection = obd.OBD(ports[0]) # connect to the first port in the list

Once a connection is made, python-OBD will load a list of the available commands in your car. A “Command” in python-OBD is an object used to query specific information from the vehicle. A command object contains its name, units, codes, and decoding functions. To get the value of a sensor, call the query() function with that sensor’s command as an argument:

import obd

connection = obd.OBD()

for command in connection.supportedCommands:
    print str(command)                      # prints the command name
    response = connection.query(command)    # sends the command, and returns the decoded response
    print response.value, response.unit     # prints the data and units returned from the car

Commands can also be accessed explicitly, either by name, or by code value. The has_command() function will determine whether or not your car supports the requested command:

import obd

connection = obd.OBD()


c = obd.commands.RPM

# OR

c = obd.commands['RPM']

# OR

c = obd.commands[1][12] # mode 1, PID 12 (decimal)


if connection.has_command(c):        # check for existance of sensor
    print connection.query(c).value  # get and print value of sensor

Here are a few of the currently supported commands (for a full list, see commands.py):

(note: support for these commands will vary from car to car)

  • Calculated Engine Load
  • Engine Coolant Temperature
  • Fuel Pressure
  • Intake Manifold Pressure
  • Engine RPM
  • Vehicle Speed
  • Timing Advance
  • Intake Air Temp
  • Air Flow Rate (MAF)
  • Throttle Position
  • Engine Run Time
  • Distance Traveled with MIL on
  • Fuel Rail Pressure (relative to vacuum)
  • Fuel Rail Pressure (direct inject)
  • Fuel Level Input
  • Number of warm-ups since codes cleared
  • Distance traveled since codes cleared
  • Evaporative system vapor pressure
  • Barometric Pressure
  • Control module voltage
  • Relative throttle position
  • Ambient air temperature
  • Commanded throttle actuator
  • Time run with MIL on
  • Time since trouble codes cleared
  • Fuel Type
  • Ethanol Fuel Percent
  • Fuel rail pressure (absolute)
  • Relative accelerator pedal position
  • Hybrid battery pack remaining life
  • Engine oil temperature
  • Fuel injection timing
  • Engine fuel rate

Debug

python-OBD also contains a debug object that can be used to print status messages and errors. Console printing is disabled by default, but can be enabled manually. A custom debug handler can also be set:

import obd

obd.debug.console = True

# AND / OR

def log(msg):
    print msg

obd.debug.handler = log

Enjoy and drive safe!

Project details


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