Andy Until we do proper tests: see the OSADL numbers for the various board / cpu setups
And this is what I get from the LCNC Integrator book (and agree with): ----------------------------- So, what do the results mean? If your Max Jitter number is less than about 15-20 microseconds (15000-20000 nanoseconds), the computer should give very nice results with software stepping. If the max latency is more like 30-50 microseconds, you can still get good results, but your maximum step rate might be a little disappointing, especially if you use microstepping or have very fine pitch leadscrews. If the numbers are 100 us or more (100,000 nanoseconds), then the PC is not a good candidate for software stepping. Numbers over 1 millisecond (1,000,000 nanoseconds) mean the PC is not a good candidate for EMC, regardless of whether you use software stepping or not. ----------------------------- With a very good setup that is tuned to perfection, for steppers you will be just on the limit with PREEMPT_RT. The 1 msec answer was very much off the cuff, and quite a while back already, and for PLC / SCADA work, which is much less demanding at least at SSAB Oxelesund. So the boards will be better today, but also our demands are higher, for steppers at least. j. On Thu, May 17, 2012 at 1:31 PM, andy pugh <bodge...@gmail.com> wrote: > On 17 May 2012 08:30, Jan de Kruyf <jan.de.kr...@gmail.com> wrote: > > > In any case, They found that in their tests "a looptime of 1 msec is no > > problem". I take it that this is with a purposely selected motherboard / > > cpu. > > 1mS loop is typical for a LinuxCNC servo / external hardware stepper > system. > However, the question is what the jitter is on that 1mS loop time. > > -- > atp > If you can't fix it, you don't own it. > http://www.ifixit.com/Manifesto > > > ------------------------------------------------------------------------------ > Live Security Virtual Conference > Exclusive live event will cover all the ways today's security and > threat landscape has changed and how IT managers can respond. Discussions > will include endpoint security, mobile security and the latest in malware > threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ > _______________________________________________ > Emc-developers mailing list > Emc-developers@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-developers > ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
