Chris Radek wrote: > On Sat, Mar 20, 2010 at 03:57:02PM -0500, Jon Elson wrote: > > >> If you look further, I think you will find there is NO tachometer in the >> machine. The Fanuc controls synthesize this from the encoder signals. >> > > The mesa hostmot2 driver has a good encoder velocity output that > considers the time stamp of the last encoder event to give smoother > output than d(counts)/dt. I'd just send that to a dac and see if it's > good enough to keep the amp happy. If it is, you have a pretty > cheap solution (just the cost of another 7i33). > > If that didn't just work, I'd quickly give up and fit real tachometers > like some others have suggested, because I bet in the long run that > is the best configuration. > Well, that's what I'm worried about, too. It seems like taking something from the encoder at the servo period, using a HAL component and then feeding out a DAC would HAVE to cause a millisecond of delay. Also, the Mesa DAC is really a PWM generator to a smoothing filter, and I don't know what the bandwidth of that filter is. With really old Fanuc phase angle servos it may not matter, with newer units with more bandwidth it could be a problem.
Jon ------------------------------------------------------------------------------ Download Intel® Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
