Reading CAN bus data into ctrlX CORE

[mreichert]

Could you please provide more information on what exactly needs to be done in the custom application in order to use the SocketCAN interface?

[CodeShepherd · Accepted solution]

Moved this topic to the forum from the how to article "Reading CAN bus data into ctrlX CORE". @Sgilk for your information.

Currently there is no way to set up the CAN interface via the ctrlX OS web interface. 

When an own snap is created it has to have access to the "network-control" interface via a corresponding slot. This is not auto connected because of security reasons. So three possible ways are available:

1. Settings are made available in the ctrX OS web ui. We created a feature for this that needs to be planned for implementation.
2. Go through the process of letting your app being signed by Rexroth, so our system will connect the interface. This would be necessary for productive machines.
3. For testing purposes request a system user assertion by Rexroth to get SSH access with a root user and connect the interface by hand. Then set up the interface by commands:
   

   $ sudo ip link set can0 type can bitrate 125000
   $ sudo ip link set up can​0

   
   This was tested by our side in some test cases already.

[Sgilk]

A couple of small clarifications on point #3 above.

• Specifically with the PCAN-USB adapter discussed in the article, the minimum bitrate is 500000. Make sure the CAN network adapater configuration matches that of the hardware device.
• Connecting the network-control interface is only necessary to execute the ip link commands within the snap context

[stefanAT_ctrlX]

in the second line above has to be also can0      (sudo ip link set up can0)  

[stefanAT_ctrlX]

The can0 is now with a green check at the settings/interfaces after    

$ sudo ip link set can0 type can bitrate 125000
$ sudo ip link set up can​0

I used bitrate 500000.

How can I use the can0 interface then in node-red? I thought to install  https://flows.nodered.org/node/node-red-contrib-socketcan  but that doesn't work (some errors occur). But I can import other nodes, connection to internet is working.

[Sgilk]

@stefanAT_ctrlX ,

I have not found any working nodes for CAN in Node-RED. It is also possible that Node-RED needs a plug added for accessing the CAN interface.

I would suggest one of the solutions in this How-To.

[stefanAT_ctrlX]

Thank you @Sgilk      ok, I will check...