2012/3/30 Charles Steinkuehler <[email protected]>: > > I do real-time on Windows, with no kernel patches! :)
Please, do not get me wrong, I am not an IT guy by any means, but I seriously doubt that non-patched windoze can be real-time (although it depends on the definition of "realtime"). AFAIK the win-based machine controls need addons for windoze to be stable and reliable in realtime and I recall seeing a number for licence of these addons alone exceeding 10K $. 0,015 s update interval is 66,666 hz update rate. I am not sure that this can really be considered realtime. At least not for machine control. Especially not for LinuxCNC (below is explained why). > I understand the importance of the latency jitter spec for folks > generating pulses via software, but it seems like it should be fairly > insignificant for hardware assisted control. I guess it depends on what is considered high jitter. 10 us back or forth for a 1 ms update cycle is not important. Add one zero to that number and it becomes significant. LinuxCNC is about being smart controller on dumb hardware, it is designed to do all the thinking part of the machine controls so that hardware does the technical tasks - generate signals, count incoming pulses etc, but all the intelligence, like closing feedback loop for servos, all the kinematic calculations etc - that is done inside LinuxCNC. Actually for fast machines (lasers, plasmas) 1 khz update rate can be too low - the velocity of such machines can easily reach 45m / min, which is 750 mm / s and which is 0,75 mm per one servo cycle - I guess that users of such machines want precision of more than 0,75 mm, so the update rate needs to be increased, which requires the jitter to be even lower than for usual cases. Viesturs ------------------------------------------------------------------------------ This SF email is sponsosred by: Try Windows Azure free for 90 days Click Here http://p.sf.net/sfu/sfd2d-msazure _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
