Don Stanley wrote: > Thanks Jon; > After I recovered from 'brain dead' and a couple more neurons started > working I realized that was probably the case. > > Are there fixed setting for PIDs, in the non servo mode; or > does it also require tuning? > Usually, no tuning is required. However since you need to set the INPUT_SCALE and OUTPUT_SCALE values for your specific machine, you may end up with the pseudo-servo situation where it never settles on some positions. If you enter a commanded position that is between step positions, it would normally just tick back and forth forever between the two nearest attainable positions. So, there is a deadband parameter in the PID component. You want to set the deadband to about 1.5 times greater than the distance equivalent to a step. You could actually set it to 1.01 x the step size, that should still always get you to a stable position.
Other than that, the numbers I have put in the sample file seem to work well over a fairly wide range of step resolutions. You can always graph performance just like on a physical servo to make sure following error is acceptable after making the _SCALE setting. Jon ------------------------------------------------------------------------------ Download new Adobe(R) Flash(R) Builder(TM) 4 The new Adobe(R) Flex(R) 4 and Flash(R) Builder(TM) 4 (formerly Flex(R) Builder(TM)) enable the development of rich applications that run across multiple browsers and platforms. Download your free trials today! http://p.sf.net/sfu/adobe-dev2dev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
