Hi Charles. If I'm not wrong in HAL you can setup "threads" as you need. So I believe that perform the PID every 1ms is too fast and not needed for a "relatively slow" temperature control. Also because you have a 20ms reading temperature cycle. If you look at the HAL User Manual you will find the info you need. As an example from the manual with a period of 1ms :
halcmd: loadrt threads name1=test-thread period1=1000000 Alex On Thu, Jun 27, 2013 at 4:56 PM, Chris Radek <[email protected]> wrote: > On Thu, Jun 27, 2013 at 09:42:37AM -0500, Charles Steinkuehler wrote: > > > I was trying some small I gains, mostly between .001 and .024. I > > _think_ the PID thread rate is being accounted for, but if not that > > could easily explain things (I'll have to dig through the code). > > The pid manpage tells you how the scaling works, and even gives an > example for Igain. > > > I suspect, however, that given the slow rates my temperature moves > > around, I may have been dealing more with integrator wind-up than with > > bad gains. > > Yes I assume you have a step command in temperature, say from 0 to > 180 degrees. You'll immediately get huge error and the output will > saturate. This saturated output is actually what you want. But > this causes I to start accumulating and it'll wind up quite a bit > before your feedback catches up. > > I doubt you want I gain at all in this situation where you expect to > have big errors. You'll probably want P and D only; D will be the > one that you tune to prevent overshoot and oscillation. > > > > ------------------------------------------------------------------------------ > This SF.net email is sponsored by Windows: > > Build for Windows Store. > > http://p.sf.net/sfu/windows-dev2dev > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ This SF.net email is sponsored by Windows: Build for Windows Store. http://p.sf.net/sfu/windows-dev2dev _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
