I will take a stab... The short answer is linuxcnc Ethernet motion is no different than any of the other interface card solution..
The longer (as I understand it) answer is... Remember that linuxcnc doesn't use motion devices like smoothstepper or galil. (these are buffering devices that move motion off of the computer.) These have advantages that the computer that is sending the data doesn't have to be realtime (or the link between the computer and the device doesn't need to be realtime). From my perspective - they have too many disadvantages. (but I am biased..) In linuxcnc - most interfaces are 'just' hardware step generators and or pwm generators and or i/o and or encoder counters and or other things I can't think of at the moment. (ie mesa, pico, vital...) This moves the heavy lifting off of the computer. So on a normal system running one of these interfaces the computer accesses the card every servo period. (maybe 1 to 10khz). This reads encoder positions, updates stepgens, pwm, i/o and so on. The link between the interface card and the computer is realtime be it pci, parallel port, ethernet.... So initially the realtime Ethernet interface was rt-net on xenomai. This worked but was a pain that a) you needed rtnet and b) There was only a few network interfaces supported... Now the Ethernet interface uses rt-preempt which is a lot less work to setup - expecially now that jeff has added support to master. (on wheezy you can use the rt_preempt kernel from synaptic) Overall - pretty exciting stuff! sam On 7/28/2014 7:11 AM, Marius Liebenberg wrote: > I am wondering about how Ethernet motion control works together with > linuxcnc. How is the synchronized motion achieved over the link? Or what > kind of information is passed over the link to the controller? > ------------------------------------------------------------------------------ Infragistics Professional Build stunning WinForms apps today! Reboot your WinForms applications with our WinForms controls. Build a bridge from your legacy apps to the future. http://pubads.g.doubleclick.net/gampad/clk?id=153845071&iu=/4140/ostg.clktrk _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
