I hooked up a C3 board from Aurturo that i had and forgotten about and a opto ,same result ,the first switch checked out fine on the scope gave a nice 2 to 5 mill sec pulse.
Just what Mach requires to see the pulse so i guess the board is the next logical step to check ,man what a pain for a few thread's ,i wrote Aurturo to see if he had a suggestion for a board.
I have a Probotix board on that second port ,i had from another mill project when i went to servo's i do not believe it is buffered and this could be the problem i am facing . I am going to try and read some on that board and see what is up with it.