obd 0.1.0

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!