On Mon, Nov 3, 2008 at 1:21 PM, William Chops Westfield <westfw@mac.com> wrote: > I don't think so. It's like a "hard real time" operating system. > "Determinism" means that you can guarantee packet delivery within a > particular maximum time; latency and jitter UP TO that time are free > to vary all over the place. > > Badly worded, I think. Variation of latency is "jitter"; but it is > the inability to guarantee a certain MAXIMUM latency, to put an upper > bound on latency, that makes the network non-deterministic... Thanks for the explanation. Maybe I should not talk about determinism and hard-realtime. Both are not necessary for many applications anyway. An article about Real Time Ethernet. http://www.datalinkcom.net/Real%20Time%20Ethernet2.pdf It mentions something like the following. "Ethernet/IP uses UDP/IP for RT communication, adding jitter and non-determinism. If the jitter is quantifiable and does not infect the system model, the system can still be RT but will be unsuitable for fast and hard RT systems like motion control." I do not quite understand this. If the jitter is quantifiable, it would have a maximum value. So it has determinism. Right? Kind of confusing. Regards, Xiaofan -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist