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.. _configuration:
Configuration
=============
Usually this library is used with a particular CAN interface, this can be
specified in code, read from configuration files or environment variables.
See :func:`can.util.load_config` for implementation.
In Code
-------
The ``can`` object exposes an ``rc`` dictionary which can be used to set
the **interface** and **channel**.
::
import can
can.rc['interface'] = 'socketcan'
can.rc['channel'] = 'vcan0'
can.rc['bitrate'] = 500000
from can.interface import Bus
bus = Bus()
You can also specify the interface and channel for each Bus instance::
import can
bus = can.interface.Bus(interface='socketcan', channel='vcan0', bitrate=500000)
Configuration File
------------------
On Linux and macOS systems the config file is searched in the following paths:
#. ``~/can.conf``
#. ``/etc/can.conf``
#. ``$HOME/.can``
#. ``$HOME/.canrc``
On Windows systems the config file is searched in the following paths:
#. ``%USERPROFILE%/can.conf``
#. ``can.ini`` (current working directory)
#. ``%APPDATA%/can.ini``
The configuration file sets the default interface and channel:
::
[default]
interface = <the name of the interface to use>
channel = <the channel to use by default>
bitrate = <the bitrate in bits/s to use by default>
The configuration can also contain additional sections (or context):
::
[default]
interface = <the name of the interface to use>
channel = <the channel to use by default>
bitrate = <the bitrate in bits/s to use by default>
[HS]
# All the values from the 'default' section are inherited
channel = <the channel to use>
bitrate = <the bitrate in bits/s to use. i.e. 500000>
[MS]
# All the values from the 'default' section are inherited
channel = <the channel to use>
bitrate = <the bitrate in bits/s to use. i.e. 125000>
::
from can.interface import Bus
hs_bus = Bus(config_context='HS')
ms_bus = Bus(config_context='MS')
Environment Variables
---------------------
Configuration can be pulled from these environmental variables:
* CAN_INTERFACE
* CAN_CHANNEL
* CAN_BITRATE
* CAN_CONFIG
The ``CAN_CONFIG`` environment variable allows to set any bus configuration using JSON.
For example:
``CAN_INTERFACE=socketcan CAN_CONFIG={"receive_own_messages": true, "fd": true}``
.. _interface names:
Interface Names
---------------
Lookup table of interface names:
+---------------------+-------------------------------------+
| Name | Documentation |
+=====================+=====================================+
| ``"canalystii"`` | :doc:`interfaces/canalystii` |
+---------------------+-------------------------------------+
| ``"cantact"`` | :doc:`interfaces/cantact` |
+---------------------+-------------------------------------+
| ``"etas"`` | :doc:`interfaces/etas` |
+---------------------+-------------------------------------+
| ``"gs_usb"`` | :doc:`interfaces/gs_usb` |
+---------------------+-------------------------------------+
| ``"iscan"`` | :doc:`interfaces/iscan` |
+---------------------+-------------------------------------+
| ``"ixxat"`` | :doc:`interfaces/ixxat` |
+---------------------+-------------------------------------+
| ``"kvaser"`` | :doc:`interfaces/kvaser` |
+---------------------+-------------------------------------+
| ``"neousys"`` | :doc:`interfaces/neousys` |
+---------------------+-------------------------------------+
| ``"neovi"`` | :doc:`interfaces/neovi` |
+---------------------+-------------------------------------+
| ``"nican"`` | :doc:`interfaces/nican` |
+---------------------+-------------------------------------+
| ``"nixnet"`` | :doc:`interfaces/nixnet` |
+---------------------+-------------------------------------+
| ``"pcan"`` | :doc:`interfaces/pcan` |
+---------------------+-------------------------------------+
| ``"robotell"`` | :doc:`interfaces/robotell` |
+---------------------+-------------------------------------+
| ``"seeedstudio"`` | :doc:`interfaces/seeedstudio` |
+---------------------+-------------------------------------+
| ``"serial"`` | :doc:`interfaces/serial` |
+---------------------+-------------------------------------+
| ``"slcan"`` | :doc:`interfaces/slcan` |
+---------------------+-------------------------------------+
| ``"socketcan"`` | :doc:`interfaces/socketcan` |
+---------------------+-------------------------------------+
| ``"socketcand"`` | :doc:`interfaces/socketcand` |
+---------------------+-------------------------------------+
| ``"systec"`` | :doc:`interfaces/systec` |
+---------------------+-------------------------------------+
| ``"udp_multicast"`` | :doc:`interfaces/udp_multicast` |
+---------------------+-------------------------------------+
| ``"usb2can"`` | :doc:`interfaces/usb2can` |
+---------------------+-------------------------------------+
| ``"vector"`` | :doc:`interfaces/vector` |
+---------------------+-------------------------------------+
| ``"virtual"`` | :doc:`interfaces/virtual` |
+---------------------+-------------------------------------+
Additional interface types can be added via the :ref:`plugin interface`.
|
