Tom Easterday wrote: > We are building a plasma/router table and are using Gecko 320X with servo > motors. The Gecko's ignore the index pulse of the encoders and so we want to > send the index pulse to EMC. We are using a D510 with parallel port and > simple parallel break out board. How fast can EMC poll an input connected > there? We can build a circuit to latch the index pulse but it would be nice > if we can just run it straight to one of the inputs.... > EMC reads the inputs as often as the thread you put the parport.read function runs. So if your BASE_PERIOD is 25000 ns, you can read 40000 times per second. Note that jitter and latency will affect the minimum pulse width you can reliably detect. Given that you're probably generating step pulses with the parallel port as well (based on the hardware you describe), you should be more or less OK.
Now, what you can do with that index input, I don't know :) The software stepgen doesn't have any way of using the index input (to latch the current step position, for example). If you're trying to home to index, it won't work right. The stepgen rawcounts parameter isn't usable in HAL (since it's a parameter rather than a pin), and the counts and position outputs are generally updated in the servo thread since they use floating point, so although you will see the index in the servo thread (you can pulse-stretch in HAL, as long as the base thread is fast enough), the position would be off by some small amount. - Steve ------------------------------------------------------------------------------ Increase Visibility of Your 3D Game App & Earn a Chance To Win $500! Tap into the largest installed PC base & get more eyes on your game by optimizing for Intel(R) Graphics Technology. Get started today with the Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs. http://p.sf.net/sfu/intelisp-dev2dev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
