On Sat, Mar 28, 2009 at 11:39:07PM -0500, Jon Elson wrote: > Hi, all, > > I'm trying to put together a jog pendant to show at NAMES. To save > digital I/O points I want to multiplex the axis selection, then I can > select 3 axes with 2 points. But, I need to do a demultiplexer, like > the reverse of the mux4 HAL component. I don't see such a component, so > maybe I am missing a simple way to do this numerically, or something. > Any ideas, or should I write a new component?
I can imagine doing it with a sprinkling of and2 and not components, or the logic component, or ladder especially if you are already using ladder. > While I'm asking questions, is there an example anywhere where a spindle > speed tach is set up to display on the VCP? I have a shaft encoder on > the spindle of my minimill, and wired to an encoder counter on my UPC > board, for threading operations. I can see that just taking encoder > delta (raw encoder counts) from the PPMC driver and multiplying by the > right factor would give RPM most of the time, but it would glitch when > the encoder counter is syncing up for threading. I'd have to hard-code > in the servo period, too. Also, a bit of filtering would give a more > stable value. Has anyone done this? Are there better signals on a HAL > pin somewhere? http://www.linuxcnc.org/docs/devel/html/hal_general_ref.html#sec:CanonEncoder It's up to the driver to figure out how to make a good velocity output. As you say, if the driver doesn't do this, you can use ddt or a delta debug output, but it won't be index-safe. Seb put a lot of effort into the velocity output of the new mesa drivers lately, and they are index-safe. It would be nice if the ppmc encoders had this feature too. I notice the hal doc doesn't specify that the velocity should be index-safe. It goes on to mention the simplest implementation which is NOT index-safe as described. John K, what was the intent? sim/lathe has a spindle speed readout you could copy. It's pretty simple. ------------------------------------------------------------------------------ _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
