On 02/05/2011 09:23 AM, Viesturs Lācis wrote (about www.rtnet.org): > What I understood from the thread in the mailing list archive, is that > would be something like reinventing the wheel. EtherCAT has all the > necessary qualities. > http://www.mail-archive.com/[email protected]/msg04138.html
But wait. Further on, PCW wrote (in 2007, replying about EtherCAT): >> I really think all of the thread raised issues have been addressed by >> Ethercat: > > Umm, no... As master, no problem but slaves will be expensive: > Ethercat slaves require either custom proprietary hardware or > proprietary IP. You can not use a generic ucontroller with Ethernet > as a EtherCat slave. Maybe things have changed since 2007? Please let us know. But look at the (current) EtherCAT hardware page (there in the green block at the top): http://www.etherlab.org/en/ethercat/hardware.php It seems to say they have a universal driver that supports all network cards that are currently supported in linux, but that you can't use it with RTAI. So although yes, the universal driver can run the network in real-time, it's not able to run in real-time under a real-time OS. (This reminds me of Bob Newhart's classic turn as Major Major in "Catch-22" who would agree to see people in his office, but only when he wasn't there:) http://www.youtube.com/watch?v=gwT-_uCEMiA So maybe rtnet.org is not re-inventing the wheel after all? Additionally, RTnet.org mentions an RT-Firewire, so maybe those who have been wanting EMC2 to run over USB would accept Firewire? Or, back to Ethernet, RTnet.org lists 12 supported NICs: http://www.rtnet.org/doc.html I wonder if EtherCAT is trademarked? And we (and slave card makers?) might have to pull out all the "EtherCAT"s the way that CentOS has to pull out all of the "Red Hat"s out of otherwise GPL'd software? And only mention "the upstream source provider"? Also, EtherCAT lists only four NIC cards as specifically supported. (I'm guessing this means running *with* a real-time OS? Not sure.) I consider a large number of supported NICs to be a feature, not a drawback. And I think manufacturers would agree, if we can get to the point where the NICs are supported generically(?) in some way so that it's not much extra work for the slave manufacturers. Or, if not, then pick a couple of popular ones and support those. And just to clarify a point, it wouldn't bother me at all if the EMC2 master PC had to have at least one real-time-only network interface in this proposed scheme. I don't see why we want to make Samba and BitTorrent available over the same network as the CNC RT control signals. Even if they can be tunneled or whatever. The RT network should IMHO connect only EMC2 and the CNC machine slaves, nothing else. So the way I see it we have to first plan a way to get simple, fast, RT I/O working from a NIC in EMC2 with an eye toward how to build the remotes, and if they can be EtherCAT or RTnet.org (or anything else) compatible, great! If they have to be something non-standard, but it's fast, simple, cheap, and reliable, it might be a reverse case of "If you come, they will build it." This is a great discussion and I think it will eventually prove valuable, please continue, everyone, with your great contributions. Thanks, Kim > First of all I would like to thank everyone, who shared their thoughts. > As a result I did another tour of web searching. > In mailing list archive I found and read the discussion, that started here: > http://www.mail-archive.com/[email protected]/msg04064.html > > 2011/2/3 andy pugh <[email protected]>: >> Try Ethercat ( http://en.wikipedia.org/wiki/EtherCAT ) > > Thanks, this helped! > I asked the initial question, because I had suspicion that using > ethernet is not self-explanatory - there are too much of different > protocols, so getting in trouble is quick, fast and easy. > > 2011/2/3 Peter C. Wallace <[email protected]>: >> I believe an individual has added Ethercat support to EMC, but only >> I/O, not drives so far as I know. > > The second attempt of searching revealed that Ulf Dambacher had some > success in getting EtherCAT working with EMC2. > http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?Etherlab > > > 2011/2/3 Dave <[email protected]>: >> I have used all these interfaces. >> >> If this is a one-off job, I would consider buying a >> protocol bridge box. . >> These boxes aren't cheap. I think they are in the $1000 plus range, but >> they work. > > Thanks for introduction on those interfaces! > I would like to avoid this suggestion of bridging different protocols, > because I have yet to learn how to handle one at a time, so dealing 2 > of them at once would be just too much for me at this moment :) > > 2011/2/4 Kim Kirwan <[email protected]>: >> Andy mentioned Ethercat, but what happened to Realtime Ethernet, >> wasn't someone working on bringing this to EMC2: >> >> http://www.rtnet.org/ > > What I understood from the thread in the mailing list archive, is that > would be something like reinventing the wheel. EtherCAT has all the > necessary qualities. > http://www.mail-archive.com/[email protected]/msg04138.html > > After looking at the wiki page, where Ulf posted the code for comp > module, I have come to conclusion that EMC can talk to any EtherCAT > slave device with according tweaks in comp module to create necessary > HAL pins. Is this correct? Could anyone else, please, comment on this? > > > By the way, are there any plans for EtherCAT I/O cards from Mesa or > Pico? I had little difficulties finding motherboardboard for the > welding robot, because D510 boards are disappearing from shops in my > country and I think that situation discussed in the previously > mentioned mail-thread of parallel port going to disappear is actually > happening. > > Viesturs > > ------------------------------------------------------------------------------ > The modern datacenter depends on network connectivity to access resources > and provide services. The best practices for maximizing a physical server's > connectivity to a physical network are well understood - see how these > rules translate into the virtual world? > http://p.sf.net/sfu/oracle-sfdevnlfb > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > > ------------------------------------------------------------------------------ The modern datacenter depends on network connectivity to access resources and provide services. The best practices for maximizing a physical server's connectivity to a physical network are well understood - see how these rules translate into the virtual world? http://p.sf.net/sfu/oracle-sfdevnlfb _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
