> Look at the bits in the wire: The PC sends a single packet that has three > 32 byte payloads for X, Y and Z. The bits are sent at one hundred million > bits per second so the time between payloads is always EXACTLY 0.00000256 > seconds. There is far less than a nanosecond of jitter in that number. > The axis synchronization is better then most of us can measure and he did > it with a laptop. > > Another way to look at it is that he does is not send the X, then the Y > then the Z. He sends (X, Y, Z) points all at once in one ethernet frame > then some time latter, more or less in real time comes the next (X,Y,Z) > point. He is getting picosecond axis sync for "free" without need for a > real time OS. > > The key is that all data for every axis is inside the same frame so the > timing is controlled by the crystal oscillator on the Ethernet card, not by > software inside Linux. We are likely looking at pico second level jitter. > > Then of course he is uses an $8,000 servo controller to hit those (x,y,z) > points so no surprise the circle is spot-on perfect.
I am also heading towards Ethercat but will not pay $8,000 for a servo controller. So far I spent only a few hours to look for linuxcnc Ethercat driver. I had only randomly working internet connection then readin last time, do you have link to the video? Or know which Ethercat driver he used? ------------------------------------------------------------------------------ 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 Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
