Peter,
>> My opinion is that you should _NEVER_ use _ANY_ I until you are within a gnats eyelash of perfect tuning. It really just gets in the way. I would make a test fixture so you can take a step motion, increase P until it overshoots in response to the step, add D until theres no or very little overshoot and repeat (increasing P and D) until you get good response to the step input. Then I would make another test with a long cruise, and adjust FF1 for minimum error. Only at this point would I start adding some I << I agree with you, and that was where I started. I then read this: http://www.linuxcnc.org/docview/html//motion_pid_theory.html Near the bottom: "If the system must remain online, one tuning method is to first set the I and D values to zero. Increase the P until the output of the loop oscillates. Then increase I until oscillation stops. Finally, increase D until the loop is acceptably quick to reach its reference. A fast PID loop tuning usually overshoots slightly to reach the setpoint more quickly; however, some systems cannot accept overshoot." Regardless, the oscillation is so bad that I cannot get a starting point for bringing in either D or I. Which is why I am suspecting I screwed up another parameter separate from PID. I just don't see it off hand. >> PDM at 6 MHz is correct, but is it selected (PWM is default)<< I am using both the 7i43 and 7i33, so the use of pwm or pdm is entirely internal to the Mesa products. The amplifier only cares about the resultant analog output. Which works best with the 7I33, pwm mode or pdm mode? What are the optimal settings? Thanks, Eric ------------------------------------------------------------------------------ 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
