> > -----Original Message----- > > From: Nicklas Karlsson [mailto:nicklas.karlsso...@gmail.com] > > > > -----Original Message----- > > > > From: Chris Albertson [mailto:albertson.ch...@gmail.com] > > > > > > > > > > The STM32 has no problem with MHz level bit flipping. Reading or > > > > creating is MHz level is not hard. > > > > And the Pi3 has to be about the most well understood and documented > > > > machines on Earth. they > > > > are ultra-common. > > > > > > > > The pi still is beat by an Intel desktop PC but the Pi has that GPIO > > > > header and you can get at signals. The OS causes unpredictable > > > > latency so use the STM32 if that matters. > > > > > > > > As for compute power if the Pi is not enough you offload from the Pi > > > > to the bigger box. But for machine tools the Pi is overkill unless > > > > you are doing vision. > > > > > > > And the STM32s are so inexpensive that the STMBL AC Servo drive uses > > two of them. One to handle the actual 3 phase drive output and one to deal > > with the encoders and user interface etc. It's a nice solution where the > > computer side (LinuxCNC) is electrically isolated from the 350V Motor side. > > > > There are good reason to place Micro controller on rectified negative rail > > while other signal need to be electrical isolated. This might be the reason > > two micro controllers are used. > > Other than frame ground an AC Servo using 350VDC derived directly from the AC > power line (w/o a transformer) must never have that 350VDC connected in any > way to the instrument DC logic (or even transformer isolated DC relay/stepper > motors). > > So now you have the issue of an encoder that uses 5V. Intelligent Serial > Control or Step/Dir or even quadrature position signals all at 5V logic > referenced to the instrument bus. Either optically couple all that at the > input of the AC Servo controller (gets expensive in both parts and board > area), or just use two processors on two boards with a high speed control > signal between them that is optically and physically isolated. > > Once again shows how clever the designers are. Were it not for the > discontinued driver device there would be many more of them out there. The > size of this unit given the power capabilities is very small compared to a > lot of other units out there. My issue right now is finding an inexpensive 3 > phase 2HP motor I can swap into my Mill Spindle. Ie. I have the cart but > not the horse... > > John Dammeyer > http://www.autoartisans.com
Now you mentioned the good reasons and I agree. Nicklas Karlsson _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
