I am trying to set up an Auto zero tool on port 1 pin 13 in mach 3 but on my breakout board it is missing the optocoupler/Isolator? along with a resistor that goes between pin 13/15 and the screw block that you screw the wires down on. Ports 10, 11,12 which are my limit switches all have those optocouplers. At least I think they are optocouplers what they look like is they are white and have 4 pins with a number p521 written on them, They are installed in locations such as U1 U2 U3 etc.. Anyways what would be the best solution to this? could I wire directly to pin 13 without any problems? I am creating my own Auto zero tool, by running a wire from this pin to a piece of aluminum. I have looked all over where would I be able to get any of those. The machine is grounded so when the bit contacts the plate it will cause a ground which wiill trigger it to auto zero. From searching I think they are the toshiba tlp521-1. Any help would be appreciated!

You can wire directly to pin 13 on the PP. The opto isolation is a safety feature meant to save your PC should you get a spike but many run all IO straight from the PP.

Have a look at this thread in the Members docs board. It may help a little.

http://www.machsupport.com/forum/index.php/topic,10088.0.html

Brett