CAN/en

The work takes place through a standard Linux subsystem - SocketCAN. CAN ports are similar to network interfaces can0 or can1, depending on the controller model. For CAN to work on controllers up to version 6.7.x, you need a terminator jumper on the port. Starting from version 6.7.x, the terminator is controlled by software and turns on automatically.

Setting

Configuring the can interface. Allow-hotplug allows the interface to rise automatically

Setting the RS485-2 port to CAN mode and enabling the can driver in linux

Via web interface

To configure via the web interface, you need to update the wb-mqtt-confed package to version 1.2.3+

Actions take place in the Configs section of the web-interface:

1. On the Network Interfaces tab, add a new interface can0 (see screenshot). Click the Save button.
2. Switch the RS-485/CAN port to CAN mode: on the Hardware Modules Configuration tab, select the settings RS485-2/CAN interface config, select in the Module type «CAN interface» and click the Save button.

The CAN interface will rise by itself when:

• system boot - service wb-hwconf-manager is responsible for this,
• change the RS-485/2 port mode to «CAN».

Using standard linux tools (automatically)

The Network Interfaces section of the web interface is a wrapper around the /etc/network/interfaces file, so CAN configuration can be done using the debian network management service. For this you need:

1. Add to /etc/network/interfaces an entry like this:

   allow-hotplug can0
   iface can0 can static
   bitrate 125000
   

2. Switch RS-485-2 port to CAN mode

We will get a result similar to setting through the web-interface.

Using standard linux tools (manually)

After switching the port to CAN mode, you need to do:

ip link set can0 up type can bitrate 125000

Working with CAN

The cansend and candump utilities are included in the controller's standard software package. If for some reason they are not there, you can install the can-utils package:

apt update && apt install can-utils

Command examples:

• Sending four bytes with address 123:

  cansend can0 123#DEADBEEF
  

• Show incoming packets:

  candump can0
  

• Показать статистику:

  cat /proc/net/can/stats
  

Обратите внимание, что в случае проблем на шине (нет терминатора, нет принимающего устройства, короткое замыкание), контроллер может прекратить работу. Для того чтобы начать работу вновь, выполните:

ifconfig can0 down && ip link set can0 up type can bitrate 125000

Больше информации смотрите в вики проекта «AmadeuS», статья «CAN bus Linux driver».