pushing the servo thread time down to 230us while you sometimes get delays that cause it to be 430us does not seem right. the latency test with a 1ms thread usually gives a max jitter of 20us with well-behaving hardware. if that works correctly down to 250us you would expect variation within 230us to 270us (?), never 430us. There was talk on the list on basing PID-caclulations (D and I terms especially) on actual measured timestamps and not assuming the thread ran on time. I'm not sure if this progressed anywhere.
> > > > > I once tried using current-sensing chips from IRF that produce > PWM-output - > > this could be one option if you want to try a current-loop. > Could you please specify which chips you tried? What do they take as an > input - PWM, analog ref, ..? > IR2175 http://www.irf.com/product-info/datasheets/data/ir2175.pdf you put a current-sensing resistor on the wire going to the motor, and this chip gives out PWM at 130kHz proportional to the current. Sorry I don't know enough about motor control to really say if&how a drive which closes the current-loop is better/different from the typical PWM-drive linuxcnc setup where only encoder feedback is present. AW ------------------------------------------------------------------------------ See everything from the browser to the database with AppDynamics Get end-to-end visibility with application monitoring from AppDynamics Isolate bottlenecks and diagnose root cause in seconds. Start your free trial of AppDynamics Pro today! http://pubads.g.doubleclick.net/gampad/clk?id=48808831&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
