Am 28.02.2014 um 14:39 schrieb Viesturs Lācis <viesturs.la...@gmail.com>:
> 2014-02-28 15:19 GMT+02:00 John Alexander Stewart <ivatt...@gmail.com>: > >> Michael; >> >> Ah - grbl-like input. Makes sense, and I can see how it would not work so >> well for LinuxCNC. >> >> The question, then, is how come Mach3 can have USB cabling, but LinuxCNC >> can't? (see the KX* mills from Arc Eurotrade in the UK; now with USB input) >> >> Related: What commands are sent over the USB for these Mach3 boxes? >> > > LinuxCNC controls the machine in realtime, whereas Mach does not. USB is let me sharpen that a bit: due to an unfortunate design decision of the current trajectory planner, the tp layer directly interacts with hardware (for spindle-synced motion to be exact). It has to run in an RT context for the latter to work. This means that in the current scheme, you _could_ send segments as generated by the tp over such a USB connection, but without further work that would loose spindle-sync because now there is no more realtime link between tp and hardware. What needs to be done, and Yishin did, is push down the syncing operation from the tp into the segment execution level, so it can be handled on such an 'outboard'. I think it would be useful to bring that functionality back mainline, because it opens options at the tp/hardware interface boundary. - Michael > not realtime, which is not important for Mach, but crucial for LinuxCNC. > AFAIK Mach sends position commands over usb, those particular cards have a > buffer (IIRC 1 to 2 seconds, please correct me, if I am wrong) and some > kind of motion control. It just seems so wrong to me as so much things can > happen during that period on a fast plasma machine or something similar. > Araisrobo have made LinuxCNC to talk to some external card (7i43?) via usb, > but I have no idea, how exactly is that done. I guess that searching > archives would bring up some more information from Yishin Li. > > Viesturs > ------------------------------------------------------------------------------ > Flow-based real-time traffic analytics software. Cisco certified tool. > Monitor traffic, SLAs, QoS, Medianet, WAAS etc. with NetFlow Analyzer > Customize your own dashboards, set traffic alerts and generate reports. > Network behavioral analysis & security monitoring. All-in-one tool. > http://pubads.g.doubleclick.net/gampad/clk?id=126839071&iu=/4140/ostg.clktrk > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ Flow-based real-time traffic analytics software. Cisco certified tool. Monitor traffic, SLAs, QoS, Medianet, WAAS etc. with NetFlow Analyzer Customize your own dashboards, set traffic alerts and generate reports. Network behavioral analysis & security monitoring. All-in-one tool. http://pubads.g.doubleclick.net/gampad/clk?id=126839071&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
