Jon, Don't use rtnet. Just use ethernet point to point to replace a parallel port. Then there is NO net stack. Just use raw ethernet packets. Overhead is then a few dozen bytes.
Ken Jon Elson wrote: > Stephen Wille Padnos wrote: >> I don't know the specifics of how to deal with the incoming packets on >> the PC (or the specifics of how to send them, for that matter :) ), but >> I'm pretty sure data throughput won't be an issue. Latency is unlikely >> to be either, unless there's some very complex packet reception >> mechanism on the PC which can't be worked around. >> > That's one of the things that worries me, I have no idea how much > overhead there is in the net stack. > Also, rtnet imposes time slots for each node, and some kind of timer > that tells each node when its time slot happens. > The master node sends a sync packet every so often, and the slave nodes > keep time off that. I'm not sure rtnet was designed at all for the kind > of VERY tight coupling we are envisioning here. Of course, rtnet > exists, but you then have to make the embedded slave nodes have a > matching protocol scheme in their stack. > > Really, for what I wanted to do with it, I don't WANT the message slot > scheduling, the HAL driver would be the master, and the slave would only > send (immediately) when commanded to. But, of course, it needs access > to the net hardware from the real time environment. > > Jon > > ------------------------------------------------------------------------------ > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users -- Kenneth Lerman Mark Kenny Products Company, LLC 55 Main Street Newtown, CT 06470 888-ISO-SEVO 203-426-7166 ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
