Thank you very much Peter.
I have some more questions that are very important for improve my
understanding of the use of OROCOS, KUKAs and real time communications.

I am using a KR60 L3 HA so I understand that I can't use FRI. However, I
see that you have also developed an RSIComponent (
http://svn.mech.kuleuven.be/repos/orocos/orocos-apps/public_release/Kuka...).
I see in the code that it is based on standard POSIX sockets, so here is
my question: Can this component communicate with the KUKA at real time?
It is possible to use the RTNet driver with such POSIX socket interface? I
think it is possible according the RTnet documentation (
http://www.rts.uni-hannover.de/rtnet/lxr/source/examples/xenomai/posix/r...)
but I have not sure if RSIComponent can work in this way.

If RSIComponent does not use the RTNet driver, can the hard-RT constraints
be guaranteed for the comunications? Is it possible to guarantee the RT
constraints using a 802.3 full duplex dedicated conection? Does it have any
sense to implement the RSIComponent using RTNet sockets API?

Concerning the issue of using a dedicated link it is nice to know that a
full duplex conection and a RT driver are enough to guarantee the real-time
constraints in the communications. However, If I were using a network hub,
the TDMA policy would be necessary, right? Would in that case the KRC able
to handle the communications? I assume that the KRC ethernet driver is real
time, but I understand that it is not able to handle the TDMA.

Thanks in advance.
Regards.

On Thu, Dec 26, 2013 at 10:43 AM, Peter Soetens <peter [..] ...>wrote:

> Hi Pablo,
>
> On Tue, Dec 24, 2013 at 12:22 PM, Pablo Iñigo Blasco <pibgeus [..] ...>
> wrote:
> >
> > Greetings.
> > I have some questions about how an OROCOS component can use the RTNet
> protocol.
> >
> > As far as I understand FRI is a library makes communication from a
> remote computer to the KRC possible through the use UDP protocol, typically
> on a IP network on a on a 802.3 network.
>
> It's not just any KRC, it's only the Kuka LWR fast research interface
> (=FRI) over Ethernet.
>
> >
> > My understanding is that the FRIComponent and the FRIRTNetComponent
> wraps that functionality in a OROCOS rt-component . Right? I think that the
> different between both components is that the RTNet component communicates
> with the KRC through a RTNet (but I'm not sure yet) Is that true?
>
> FRIRTNetComponent goes over raw RTNet sockets (so using rtnet linux
> drivers for Ethernet), but without any of the extra's like TDMA etc.
>
> >
> > If so, there are several things that I do not understand. How the KRC
> can participate in a RTNet? Does the KRC use a MAC layer with a TDMA
> discipline? Is compatible 802.3 with an RTNet?
>
> Yes, raw RTNet is compatible with 802.3. You can't really see on the
> wire that it came from an rtnet socket, it's just an ethernet frame
> sent by a real-time linux driver, containing an UDP packet. We avoid
> collisions and timing issues by using a dedicated link from PC to
> Kuka.
>
> Peter
>