On Monday 30 October 2017 17:07:28 Nicklas Karlsson wrote: > > A real time host is still needed for CNC coordinated motion with > > Ethercat slaves. Ethercat does no change this at all. Laptops will > > work in some circumstances but can cause troubles with multiple ms > > real time delays when doing power management tasks. > > A smart device could figure out the correct point in time then it > should happen to drive the operator crazy or else Murphys will help. > > > Also RPIs are not good real time Ethernet masters for a couple of > > reasons > > > > 1. The Ethernet is routed through USB which has terrible real time > > characteristics > > USB is fast but in practice I guess the extra USB layer in between > Ethernet do nothing good for the real time charteristic. > > > 2. The RPI is too slow to have decent real time network performance > > with Preempt-RT > > Might be but I think it's fast enough if not interrupted by something > else. > The pi can handle any interrupt in real time IF its not coming in thru the internal usb hub.
None of the spi stuff data goes thru that path, so it runs the machine flawlessly. Its the human interface stuff that goes thru the internal usb hub, and quite often is missed. > > As far as LinuxCNCs architecture goes, keeping the real time > > portions of motion in the host are required to retain the power, > > extensibility, and flexibility of HAL, You can of course move HAL to > > a remote ucontroller that supports floating point and dynamic object > > loading, but then you have two OSes to maintain rather than 1. > > Tow OSes is certainly a drawback but I guess it would also be possible > to connect user interface via ordinary network or run without GUI. > > ---------------------------------------------------------------------- >-------- Check out the vibrant tech community on one of the world's > most engaging tech sites, Slashdot.org! http://sdm.link/slashdot > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
