write a HAL componet for canopen commnunication

ztj_1 wrote:

I have known that socketcan was embeded into kernel, but i found that users can only use it in userspace level. I want to ask if it is possible for me to make a realtime module with canopen conmunication? so that I can write a gule module for linuxcnc.

Do you want to control devices that require realtime communication? I believe that the Modbus implementation in LinuxCNC only works in userspace, but is still useful to people.

Which physical output port on the PC would be used?

ztj_1 wrote:

I use PCI to can card ADLINK7841

Looking at the datasheet it says "Direct memory mapping to the CAN controllers" and that might be the way to approach the problem, write a direct-access driver for HAL.

If you look here:
git.linuxcnc.org/gitweb?p=linuxcnc.git;a...e74b607c0ef4;hb=HEAD

You will see pcl720.comp which is a very simple driver written in "comp" for an ISA card. You could write something rather like that, but using elements from (for example) AX5214H.c which is a PCI card driver, though written in C instead.