There are motor drivers that have internal logic to automatically reduce the drive current while idle. These will weakly hold position and run much cooler when at rest. They can resume full power instantly when a step pulse arrives. Of course, this is a feature that the driver either has or doesn't have, no signal from EMC can produce this result if the driver does not support it.
Steve Stallings > -----Original Message----- > From: Jeff Epler [mailto:[email protected]] > Sent: Thursday, July 02, 2009 7:59 AM > To: Enhanced Machine Controller (EMC) > Subject: Re: [Emc-users] power off at the end of program > > On Thu, Jul 02, 2009 at 08:41:23AM +0200, Denis Stremplewski wrote: > > Hi, > > Does exist a way for automatically shutting off the power of the > > motors at the end of a program (something like Mxx), in > order to avoid > > a self heating of the motors ? > > You don't want to do this. > > In a stepper system, any time you turn off the amplifier you > risk losing position. That's because when you turn the > amplifier back on, even if it powers on in the same phase as > it powered off, it might pull in to a spot +-4 full steps > from where it was powered off. Furthermore, there's no > warning before an interactive jog can begin, so you can't > make sure that the amplifier has had a chance to turn on > before the first step is made. Any time the amplifier is > turned off in a stepper system, you should assume that you > have lost position and need to re-home and/or touch off again. > > Instead, follow your motors' datasheet maximum current and > case temperature limits, and live with the fact that a > stepper gets hot to the touch even when operated properly. > > Jeff > > -------------------------------------------------------------- > ---------------- > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
