Re: [Emc-users] CANopen over Ethernet CiA 309

[Nicklas K. <nic...@gm...>]

On Wed, 21 Feb 2018 14:26:36 -0800
"John Dammeyer" <jo...@au...> wrote:

> There are some other reference documents out there.
> https://www.can-cia.org/fileadmin/resources/documents/proceedings/2005_rosta
> n.pdf

Link had broken line https://www.can-cia.org/fileadmin/resources/documents/proceedings/2005_rostan.pdf

> https://en.wikipedia.org/wiki/EtherCAT
> 
> However, one probably has to first decide why they even want it.  Most of
> the CANopen devices out there are CAN bus based.  A few higher end units
> support EtherCat.

I will use Ethercat but data sent in the Ethercat frames could follow the CANopen standard. As is now there is SOES on the slave I think anyway and SOEM on the Linucnc side and it use some kind of CANopen communication at startup although I did not yet have time to investigate further.

Configuration could be added to Linuxcnc but to add a standard gateway feels like a better solution.

> Something like a tool changer is an ideal candidate for a CANopen control
> system.  Kept modular it could be as simple as handling the request to load
> a tool and a reply that the tool is loaded along with the offset off the
> tool.

This is send and wait for answer or acknowledge. CANopen may also send periodic data and watchdog if not received is better solution in some cases like if cable is broken.

> Interfaced in this manner the tool changer becomes a black box.  The CNC
> system doesn't need to know how many motors, switches or other items are
> part of the system.  Whether it's a EtherCat Bridge to CANopen or just a USB
> to CAN dongle, the ultimate CANopen messages remain the same.
> 
> So what solution are you looking for that CANopen over Ethernet is a choice?

TCP/IP gateway will only be used to interface a standard configuration software instead of adding this to Linuxcnc.


Nicklas Karlsson