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

Работа с CAN

Утилиты cansend и candump есть в стандартном наборе ПО контроллера. Если по каким-то причинам их нет, можно поставить пакет can-utils:

apt update && apt install can-utils

Примеры команд:

• Отправка четырех байт c адресом 123:

  cansend can0 123#DEADBEEF
  

• Показывать входящие пакеты:

  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».