Hello Jon and thanks for the quick answer. I was affraid that it would be on the limit. I guess I'm going to use a 5i20 to read it. I have one machine using it so I can test it with the TTL encoder and see how it works.
Do you know if the 6i25 is already supported by LinuxCNC? I know that hostmot 2 works with it, but I don't know if there is support for that particular card on LinuxCNC. Leonardo. 2013/9/30 Jon Elson <el...@pico-systems.com> > On 09/30/2013 12:05 PM, Leonardo Marsaglia wrote: > > Hello to all. > > > > I need to control a screw with an encoder mounted on it. Calculating the > > max rpm and the resolution I want I need a 25 khz read response for the > > encoder. > > > > I remember reading somewhere the maximum expected frequency of the > parport > > software driver to read an input but I don't remember where. > > > > I would like to know please if any of you have an approximation of the > > frequency, because If this works I can save some money. If not, I would > > have to buy dedicated hardware. > > > > > The port, itself, has no frequency limit. It takes about 1 us to read > the legacy ports, and > the motherboard puts the CPU in a wait state while it is doing it. But, > reading a > single register of the parport hardware will just take about 1 us, at > the lowest > level. The hal_parport driver is fairly efficient, and you only need > one instance of > the software encoder component should also be fairly efficient. If you > need to detect > position every 25 us, this could be a problem. If you just want to be > sure that encoder > counts are not lost, then this should work fine. > > Later motherboards with PCI-connected parports are a bit faster. You > should be > able to run a 25 us (25000 ns) base thread on a good CPU. > > Jon > > > ------------------------------------------------------------------------------ > October Webinars: Code for Performance > Free Intel webinars can help you accelerate application performance. > Explore tips for MPI, OpenMP, advanced profiling, and more. Get the most > from > the latest Intel processors and coprocessors. See abstracts and register > > http://pubads.g.doubleclick.net/gampad/clk?id=60133471&iu=/4140/ostg.clktrk > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > -- *Leonardo Marsaglia*. ------------------------------------------------------------------------------ October Webinars: Code for Performance Free Intel webinars can help you accelerate application performance. Explore tips for MPI, OpenMP, advanced profiling, and more. Get the most from the latest Intel processors and coprocessors. See abstracts and register > http://pubads.g.doubleclick.net/gampad/clk?id=60133471&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
