Steve Blackmore wrote: > On Wed, 30 Sep 2009 21:07:45 -0500, you wrote: > > > >> OK, good, but what is the rate of the bate thread set to? That value is >> brought over >> > >from a line in your xxxx.ini file. There are probably 3 lines that read > >> something like : >> # Base task period, in nanoseconds - this is the fastest thread in the >> machine >> BASE_PERIOD = 50000 >> # Servo task period, in nanoseconds - will be rounded to an integer multiple >> # of BASE_PERIOD >> SERVO_PERIOD = 1000000 >> # Trajectory Planner task period, in nanoseconds - will be rounded to an >> # integer multiple of SERVO_PERIOD >> TRAJ_PERIOD = 10000000 >> > > Hi Jon > > Here is the complete EMCMOT section > > [EMCMOT] > EMCMOT = motmod > COMM_TIMEOUT = 1.0 > COMM_WAIT = 0.010 > BASE_PERIOD = 30000 > SERVO_PERIOD = 1000000 > > > There is no TRAJ_PERIOD anywhere in the ini file, nor in another test > setup I created using stepconf yesterday - should there be? > > I'm not sure, this may have become obsolete in a recent EMC2 update. I think it was found that running the trajectory planner at a fraction of the servo rate was no longer of much benefit.
So, the BASE_PERIOD is 30 us. With this, it shouldn't be missing counts, even with a fairly high encoder resolution and high spindle speeds. So, it looks like the sampling rate is NOT the cause of the problem. 30 us should allow very safe counting at up to 10 K counts/second. With a 100 cycle/rev encoder (400 counts/rev), you should be able to handle 25 revs/second or 1500 RPM. (Not sure of your encoder resolution, just throwing out a number.) So, it comes down to either something else in EMC is fouling up the handling of the encoder, or the encoder is producing bad signals or the computer is not reading the voltage levels correctly. Some poking around with HalScope should reveal where the problem is. Now, are you using regular quadrature counting, or just counting edges on one track? If just counting edges, any noise in the signal will be counted as an edge! Not a good choice unless the encoder signal is ROCK solid. Quadrature allows it to handle a bit of noise at the transitions without getting false counts. That could make a big difference. Jon ------------------------------------------------------------------------------ Come build with us! The BlackBerry® Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9-12, 2009. Register now! http://p.sf.net/sfu/devconf _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
