Kirk Wallace wrote: > I am looking into adding a knob for setting spindle speed manually. This > serial encoder is close to what I am looking for: > > http://www.usdigital.com/products/a2/ > > but is over-kill and way too expensive. Does anyone have a link to an 8 > or 10 bit serial (SPI like) absolute encoder? I checked Digikey but > didn't find anything. Other options are to use a potentiometer and > serial ADC or PWM to serial, but an inexpensive single unit would be > better. Thanks.
I would not recommend absolute encoders (or pots with A/Ds, which are also absolute). Think about something like feed override, where the is a slider on the GUI as well as a physical knob. If you turn the knob, EMC will adjust the position of the slider to match. But if you move the GUI slider, it is impossible to turn the knob to match. If you use an incremental encoder with no scale, then it can coexist nicely with the GUI slider (or with other physical controls - for example you could have a knob at the machine control, and another knob located on the far side of a large machine table. Another example would be on-off controls like spindle or coolant. If you use a toggle switch, you can have only one. If you use start and stop buttons, you can have as many of each as you want. This concept of using incremental controls is a fundamental principle adopted by NIST when they were designing EMC. Think long and hard about the implications before you switch to absolute controls. Regards, John Kasunich ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
